Nature , IF:42.778 , 2020 Nov doi: 10.1038/s41586-020-2940-2
A network of transcriptional repressors modulates auxin responses.
Laboratoire Reproduction et Developpement des Plantes, Universite de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, Lyon, France.; School of Biosciences, University of Nottingham, Loughborough, UK.; School of Mathematical Sciences, University of Nottingham, Nottingham, UK.; Department of Plant Biology, University of California Davis, Davis, CA, USA.; Genome Center, University of California Davis, Davis, CA, USA.; Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland.; Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.; Universite Grenoble Alpes, CNRS, CEA, INRAE, IRIG-DBSCI-LPCV, Grenoble, France.; School of Biosciences, University of Nottingham, Loughborough, UK. Anthony.Bishopp@nottingham.ac.uk.; Laboratoire Reproduction et Developpement des Plantes, Universite de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, Lyon, France. teva.vernoux@ens-lyon.fr.
The regulation of signalling capacity, combined with the spatiotemporal distribution of developmental signals themselves, is pivotal in setting developmental responses in both plants and animals(1). The hormone auxin is a key signal for plant growth and development that acts through the AUXIN RESPONSE FACTOR (ARF) transcription factors(2-4). A subset of these, the conserved class A ARFs(5), are transcriptional activators of auxin-responsive target genes that are essential for regulating auxin signalling throughout the plant lifecycle(2,3). Although class A ARFs have tissue-specific expression patterns, how their expression is regulated is unknown. Here we show, by investigating chromatin modifications and accessibility, that loci encoding these proteins are constitutively open for transcription. Through yeast one-hybrid screening, we identify the transcriptional regulators of the genes encoding class A ARFs from Arabidopsis thaliana and demonstrate that each gene is controlled by specific sets of transcriptional regulators. Transient transformation assays and expression analyses in mutants reveal that, in planta, the majority of these regulators repress the transcription of genes encoding class A ARFs. These observations support a scenario in which the default configuration of open chromatin enables a network of transcriptional repressors to regulate expression levels of class A ARF proteins and modulate auxin signalling output throughout development.
PMID: 33208947
Nature , IF:42.778 , 2020 Nov , V587 (7832) : P103-108 doi: 10.1038/s41586-020-2778-7
A single bacterial genus maintains root growth in a complex microbiome.
Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.; Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.; Department of Plant and Environmental Sciences, Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel.; Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.; Future Food Beacon of Excellence, School of Biosciences, University of Nottingham, Sutton Bonington, UK.; Department of Biology, 'Luiz de Queiroz' College of Agriculture (ESALQ), University of Sao Paulo (USP), Piracicaba, Brazil.; Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.; Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. dangl@email.unc.edu.; Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. dangl@email.unc.edu.; Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. dangl@email.unc.edu.; Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. dangl@email.unc.edu.; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. dangl@email.unc.edu.; Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. dangl@email.unc.edu.
Plants grow within a complex web of species that interact with each other and with the plant(1-10). These interactions are governed by a wide repertoire of chemical signals, and the resulting chemical landscape of the rhizosphere can strongly affect root health and development(7-9,11-18). Here, to understand how interactions between microorganisms influence root growth in Arabidopsis, we established a model system for interactions between plants, microorganisms and the environment. We inoculated seedlings with a 185-member bacterial synthetic community, manipulated the abiotic environment and measured bacterial colonization of the plant. This enabled us to classify the synthetic community into four modules of co-occurring strains. We deconstructed the synthetic community on the basis of these modules, and identified interactions between microorganisms that determine root phenotype. These interactions primarily involve a single bacterial genus (Variovorax), which completely reverses the severe inhibition of root growth that is induced by a wide diversity of bacterial strains as well as by the entire 185-member community. We demonstrate that Variovorax manipulates plant hormone levels to balance the effects of our ecologically realistic synthetic root community on root growth. We identify an auxin-degradation operon that is conserved in all available genomes of Variovorax and is necessary and sufficient for the reversion of root growth inhibition. Therefore, metabolic signal interference shapes bacteria-plant communication networks and is essential for maintaining the stereotypic developmental programme of the root. Optimizing the feedbacks that shape chemical interaction networks in the rhizosphere provides a promising ecological strategy for developing more resilient and productive crops.
PMID: 32999461
Cell , IF:38.637 , 2020 Nov , V183 (4) : P875-889.e17 doi: 10.1016/j.cell.2020.09.043
Genomes of the Banyan Tree and Pollinator Wasp Provide Insights into Fig-Wasp Coevolution.
Center for Genomics and Biotechnology, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Key Laboratory of Genetics, Breeding and Multiple Utilization of Crops, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002.; CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303.; Department of Agronomy, National Taiwan University, Taipei, Taiwan 10617.; Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241.; CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303. Electronic address: cj@xtbg.org.cn.; Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. Electronic address: rayming@illinois.edu.
Banyan trees are distinguished by their extraordinary aerial roots. The Ficus genus includes species that have evolved a species-specific mutualism system with wasp pollinators. We sequenced genomes of the Chinese banyan tree, F. microcarpa, and a species lacking aerial roots, F. hispida, and one wasp genome coevolving with F. microcarpa, Eupristina verticillata. Comparative analysis of the two Ficus genomes revealed dynamic karyotype variation associated with adaptive evolution. Copy number expansion of auxin-related genes from duplications and elevated auxin production are associated with aerial root development in F. microcarpa. A male-specific AGAMOUS paralog, FhAG2, was identified as a candidate gene for sex determination in F. hispida. Population genomic analyses of Ficus species revealed genomic signatures of morphological and physiological coadaptation with their pollinators involving terpenoid- and benzenoid-derived compounds. These three genomes offer insights into and genomic resources for investigating the geneses of aerial roots, monoecy and dioecy, and codiversification in a symbiotic system.
PMID: 33035453
Mol Plant , IF:12.084 , 2020 Nov doi: 10.1016/j.molp.2020.11.011
MPK14-mediated auxin signaling controls lateral root development via ERF13 regulated very-long-chain fatty acids (VLCFAs) biosynthesis.
The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, Shandong, China; College of Horticulture, Qingdao Agricultural University, Qingdao, 266109, Shandong, China.; The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, Shandong, China.; State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Taian 271018, Shandong, China.; State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian 271018, Shandong, China.; State Key Laboratory of Crop Biology, College of Forestry, Shandong Agricultural University, Taian 271018, Shandong, China.; The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, Shandong, China. Electronic address: dingzhaojun@sdu.edu.cn.
Auxin plays a critical role in lateral root (LR) formation. The signaling module composed of auxin responsive factors (ARFs)-lateral organ boundaries-domain transcription factors (LBDs) mediates auxin signaling to control almost every stage of LR development. Here, we show that auxin-induced degradation of the APETALA2/Ethylene Responsive Factor (AP2/ERF) transcription factor ERF13, dependent on MITOGEN-ACTIVATED PROTEIN KINASE MPK14-mediated phosphorylation, plays an essential role in LR development. Overexpression of ERF13 results in restricted passage of the LR primordia (LRP) through the endodermal layer, leading to highly reduced LR emergence. ERF13 inhibits the expression of 3-ketoacyl-CoA synthase16 (KCS16), which encodes a fatty acid elongase involved in very-long-chain fatty acids (VLCFAs) biosynthesis. Overexpression of KCS16 or exogenous VLCFAs treatment rescues the LR emergence defects in ERF13 overexpression lines, indicating a role downstream of the auxin-MPK14-ERF13 signaling module. In conclusion, this study uncovers a novel molecular mechanism of MPK14-mediated auxin signaling in LR development via ERF13-regulated VLCFAs biosynthesis.
PMID: 33221411
Mol Plant , IF:12.084 , 2020 Nov doi: 10.1016/j.molp.2020.11.004
Pho-view of Auxin: Reversible Protein Phosphorylation in Auxin Biosynthesis, Transport and Signalling.
Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria.; Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Muthgasse 18, 1190 Wien, Austria.; Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria. Electronic address: jiri.friml@ist.ac.at.
The phytohormone auxin plays a central role in shaping plant growth and development. With decades of genetic and biochemical studies, numerous core molecular components and their networks, underlying auxin biosynthesis, transport and signalling, have been identified. Notably, protein phosphorylation, catalysed by kinases and oppositely hydrolysed by phosphatases, has been emerging to be a crucial type of post-translational modification, regulating physiological and developmental auxin output at all levels. In this review, we comprehensively discuss earlier and recent advances in our understanding of genetics, biochemistry and cell biology of the kinases and phosphatases participating in auxin action. We provide insights into mechanisms, by which reversible protein phosphorylation defines developmental auxin responses, discuss the current challenges, and also propose our perspectives for further directions to integrate control of protein phosphorylation into the molecular auxin network.
PMID: 33186755
Dev Cell , IF:10.092 , 2020 Nov doi: 10.1016/j.devcel.2020.10.019
Regulation of ARGONAUTE10 Expression Enables Temporal and Spatial Precision in Axillary Meristem Initiation in Arabidopsis.
Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, CA 92521, USA.; Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, CA 92521, USA.; State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and National Center for Plant Gene Research, Beijing 100101, China.; Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.; Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, CA 92521, USA. Electronic address: xuemei.chen@ucr.edu.
Axillary meristems (AMs) give rise to lateral shoots and are critical to plant architecture. Understanding how developmental cues and environmental signals impact AM development will enable the improvement of plant architecture in agriculture. Here, we show that ARGONAUTE10 (AGO10), which sequesters miR165/166, promotes AM development through the miR165/166 target gene REVOLUTA. We reveal that AGO10 expression is precisely controlled temporally and spatially by auxin, brassinosteroids, and light to result in AM initiation only in the axils of leaves at a certain age. AUXIN RESPONSE FACTOR 5 (ARF5) activates while BRASSINAZOLE-RESISTANT 1 (BZR1) and PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) repress AGO10 transcription directly. In axils of young leaves, BZR1 and PIF4 repress AGO10 expression to prevent AM initiation. In axils of older leaves, ARF5 upregulates AGO10 expression to promote AM initiation. Our results uncover the spatiotemporal control of AM development through the cooperation of hormones and light converging on a regulator of microRNA.
PMID: 33232670
EMBO J , IF:9.889 , 2020 Nov : Pe104416 doi: 10.15252/embj.2020104416
Flavonol-mediated stabilization of PIN efflux complexes regulates polar auxin transport.
Institute of Biology II, University of Freiburg, Freiburg, Germany.; Institute of Physiology II, Faculty of Medicine, University of Freiburg, Freiburg, Germany.; Institute for Computer Science, University of Freiburg, Freiburg, Germany.; Department of Agronomy, Food, Natural resources, Animals and Environment-DAFNAE, University of Padova, Padova, Italy.; High-Throughput Binder Selection Facility, Department of Biochemistry, University of Zurich, Zurich, Switzerland.; Sino German Joint Research Center for Agricultural Biology, and State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.; Logopharm GmbH, Freiburg, Germany.; Signalling Research Centres BIOSS and CIBSS, Freiburg, Germany.
The transport of auxin controls the rate, direction and localization of plant growth and development. The course of auxin transport is defined by the polar subcellular localization of the PIN proteins, a family of auxin efflux transporters. However, little is known about the composition and regulation of the PIN protein complex. Here, using blue-native PAGE and quantitative mass spectrometry, we identify native PIN core transport units as homo- and heteromers assembled from PIN1, PIN2, PIN3, PIN4 and PIN7 subunits only. Furthermore, we show that endogenous flavonols stabilize PIN dimers to regulate auxin efflux in the same way as does the auxin transport inhibitor 1-naphthylphthalamic acid (NPA). This inhibitory mechanism is counteracted both by the natural auxin indole-3-acetic acid and by phosphomimetic amino acids introduced into the PIN1 cytoplasmic domain. Our results lend mechanistic insights into an endogenous control mechanism which regulates PIN function and opens the way for a deeper understanding of the protein environment and regulation of the polar auxin transport complex.
PMID: 33185277
Plant Cell , IF:9.618 , 2020 Nov , V32 (11) : P3452-3468 doi: 10.1105/tpc.18.00471
Developmental Genetics of Corolla Tube Formation: Role of the tasiRNA-ARF Pathway and a Conceptual Model.
Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut 06269 ding.baoqing@gmail.com yuan.colreeze@gmail.com.; State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, Guangdong 510642, China.; Donald Danforth Plant Science Center, St. Louis, Missouri 63132.; Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut 06269.; Division of Plant Sciences, University of Missouri, Columbia, Missouri 65211.; Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut 06269.
Over 80,000 angiosperm species produce flowers with petals fused into a corolla tube. The corolla tube contributes to the tremendous diversity of flower morphology and plays a critical role in plant reproduction, yet it remains one of the least understood plant structures from a developmental genetics perspective. Through mutant analyses and transgenic experiments, we show that the tasiRNA-ARF pathway is required for corolla tube formation in the monkeyflower species Mimulus lewisii Loss-of-function mutations in the M. lewisii orthologs of ARGONAUTE7 and SUPPRESSOR OF GENE SILENCING3 cause a dramatic decrease in abundance of TAS3-derived small RNAs and a moderate upregulation of AUXIN RESPONSE FACTOR3 (ARF3) and ARF4, which lead to inhibition of lateral expansion of the bases of petal primordia and complete arrest of the upward growth of the interprimordial regions, resulting in unfused corollas. Using the DR5 auxin-responsive promoter, we discovered that auxin signaling is continuous along the petal primordium base and the interprimordial region during the critical stage of corolla tube formation in the wild type, similar to the spatial pattern of MlARF4 expression. Auxin response is much weaker and more restricted in the mutant. Furthermore, exogenous application of a polar auxin transport inhibitor to wild-type floral apices disrupted petal fusion. Together, these results suggest a new conceptual model highlighting the central role of auxin-directed synchronized growth of the petal primordium base and the interprimordial region in corolla tube formation.
PMID: 32917737
Plant Cell , IF:9.618 , 2020 Nov , V32 (11) : P3485-3499 doi: 10.1105/tpc.19.00695
Auxin Regulates Sucrose Transport to Repress Petal Abscission in Rose (Rosa hybrida).
State Key Laboratory of Agrobiotechnology, Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture, College of Horticulture, China Agricultural University, Beijing 100193, China.; State Key Laboratory of Agrobiotechnology, Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture, College of Horticulture, China Agricultural University, Beijing 100193, China mac@cau.edu.cn gaojp@cau.edu.cn.; Robert W. Holley Center for Agriculture and Health, United States Department of Agriculture, Agricultural Research Service, Ithaca, New York 14853.; Boyce Thompson Institute, Ithaca, New York 14853.; Crops Pathology and Genetic Research Unit, United States Department of Agriculture, Agricultural Research Service, Davis, California 95616.; Department of Plant Sciences, University of California at Davis, Davis, California 95616.
Developmental transitions in plants require adequate carbon resources, and organ abscission often occurs due to competition for carbohydrates/assimilates. Physiological studies have indicated that organ abscission may be activated by Suc deprivation; however, an underlying regulatory mechanism that links Suc transport to organ shedding has yet to be identified. Here, we report that transport of Suc and the phytohormone auxin to petals through the phloem of the abscission zone (AZ) decreases during petal abscission in rose (Rosa hybrida), and that auxin regulates Suc transport into the petals. Expression of the Suc transporter RhSUC2 decreased in the AZ during rose petal abscission. Similarly, silencing of RhSUC2 reduced the Suc content in the petals and promotes petal abscission. We established that the auxin signaling protein RhARF7 binds to the promoter of RhSUC2, and that silencing of RhARF7 reduces petal Suc contents and promotes petal abscission. Overexpression of RhSUC2 in the petal AZ restored accelerated petal abscission caused by RhARF7 silencing. Moreover, treatment of rose petals with auxin and Suc delayed ethylene-induced abscission, whereas silencing of RhARF7 and RhSUC2 accelerated ethylene-induced petal abscission. Our results demonstrate that auxin modulates Suc transport during petal abscission, and that this process is regulated by a RhARF7-RhSUC2 module in the AZ.
PMID: 32843436
Curr Biol , IF:9.601 , 2020 Nov doi: 10.1016/j.cub.2020.10.077
NO GAMETOPHORES 2 Is a Novel Regulator of the 2D to 3D Growth Transition in the Moss Physcomitrella patens.
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK. Electronic address: laura.moody@plants.ox.ac.uk.; Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
The colonization of land by plants was one of the most transformative events in the history of life on Earth. The transition from water, which coincided with and was likely facilitated by the evolution of three-dimensional (3D) growth, enabled the generation of morphological diversity on land. In many plants, the transition from two-dimensional (2D) to 3D growth occurs during embryo development. However, in the early divergent moss Physcomitrella patens, 3D growth is preceded by an extended filamentous phase that can be maintained indefinitely. Here, we describe the identification of the cytokinin-responsive NO GAMETOPHORES 2 (PpNOG2) gene, which encodes a shikimate o-hydroxycinnamoyltransferase. In mutants lacking PpNOG2 function, transcript levels of CLAVATA and SCARECROW genes are significantly reduced, excessive gametophore initial cells are produced, and buds undergo premature developmental arrest. Mutants also exhibit misregulation of auxin-responsive genes. Our results suggest that PpNOG2 functions in the ascorbic acid pathway leading to cuticle formation and that NOG2-related genes were co-opted into the lignin biosynthesis pathway after the divergence of bryophytes and vascular plants. We present a revised model of 3D growth in which PpNOG2 comprises part of a feedback mechanism that is required for the modulation of gametophore initial cell frequency. We also propose that the 2D to 3D growth transition in P. patens is underpinned by complex auxin-cytokinin crosstalk that is regulated, at least in part, by changes in flavonoid metabolism.
PMID: 33242390
Curr Biol , IF:9.601 , 2020 Nov doi: 10.1016/j.cub.2020.10.008
CLAVATA Signaling Ensures Reproductive Development in Plants across Thermal Environments.
Department of Biology, University of North Carolina at Chapel Hill, 250 Bell Tower Drive, Chapel Hill, NC 27599, USA.; Department of Biology, University of North Carolina at Chapel Hill, 250 Bell Tower Drive, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. Electronic address: zackn@email.unc.edu.
The ability to thrive in diverse environments requires that species maintain development and reproduction despite dynamic conditions. Many developmental processes are stabilized through robust signaling pathways that cooperatively ensure proper development.(1) During reproduction, plants like Arabidopsis thaliana continuously generate flowers on growing indeterminate inflorescences.(2) Flower primordia initiation and outgrowth depends on the hormone auxin and is robust across diverse environments.(3-6) Here, we show that reproductive development under different thermal conditions requires the integration of multiple pathways regulating auxin-dependent flower production. In colder/ambient temperatures, the receptor complex CLAVATA2/CORYNE (CLV2/CRN) is necessary for continuous flower outgrowth during inflorescence development. CLV2/CRN signaling is independent of CLAVATA1 (CLV1)-related receptor signaling but involves the CLAVATA3 INSENSITIVE RECEPTOR KINASE (CIK) family co-receptors, with higher order cik mutant combinations phenocopying clv2/crn flower outgrowth defects. Developing crn inflorescences display reduced auxin signaling, and restoration of auxin biosynthesis is sufficient to restore flower outgrowth in colder and ambient temperatures. In contrast, at higher temperatures, both clv2/crn signaling and heat-induced auxin biosynthesis via YUCCA family genes are synergistically required to maintain flower development. Our work reveals a novel mechanism integrating peptide hormone and auxin signaling in the regulation of flower development across diverse thermal environments.
PMID: 33157018
Curr Biol , IF:9.601 , 2020 Nov , V30 (22) : P4384-4398.e5 doi: 10.1016/j.cub.2020.08.053
Pluripotent Pericycle Cells Trigger Different Growth Outputs by Integrating Developmental Cues into Distinct Regulatory Modules.
ZMBP-Center for Plant Molecular Biology, University of Tubingen, Auf der Morgenstelle 32, 72076 Tubingen, Germany.; Institute of Biology, University of Neuchatel, Rue Emile-Argand 11, 2000 Neuchatel, Switzerland.; ZMBP-Center for Plant Molecular Biology, University of Tubingen, Auf der Morgenstelle 32, 72076 Tubingen, Germany. Electronic address: laura.ragni@zmbp.uni-tuebingen.de.
During post-embryonic development, the pericycle specifies the stem cells that give rise to both lateral roots (LRs) and the periderm, a suberized barrier that protects the plant against biotic and abiotic stresses. Comparable auxin-mediated signaling hubs regulate meristem establishment in many developmental contexts; however, it is unknown how specific outputs are achieved. Using the Arabidopsis root as a model, we show that while LR formation is the main auxin-induced program after de-etiolation, plants with age become competent to form a periderm in response to auxin. The establishment of the vascular cambium acts as the developmental switch required to trigger auxin-mediated periderm initiation. Moreover, distinct auxin signaling components and targets control LR versus periderm formation. Among the periderm-specific-promoting transcription factors, WUSCHEL-RELATED HOMEOBOX 4 (WOX4) and KNAT1/BREVIPEDICELLUS (BP) stand out as their specific overexpression in the periderm results in an increased number of periderm layers, a trait of agronomical importance in breeding programs targeting stress tolerance. These findings reveal that specificity in pericycle stem cell fate is achieved by the integration of developmental cues into distinct regulatory modules.
PMID: 32916110
Proc Natl Acad Sci U S A , IF:9.412 , 2020 Nov doi: 10.1073/pnas.2013305117
The Arabidopsis NRT1/PTR FAMILY protein NPF7.3/NRT1.5 is an indole-3-butyric acid transporter involved in root gravitropism.
RIKEN Center for Sustainable Resource Science, Kanagawa 230-0045, Japan.; Graduate School of Science and Technology, Nara Institute of Science and Technology, Nara 630-0192, Japan.; Department of Biological Production Science, United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.; Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.; Department of Biochemistry, Okayama University of Science, Okayama 700-0005, Japan.; RIKEN Center for Sustainable Resource Science, Kanagawa 230-0045, Japan; mitsunori.seo@riken.jp.
Active membrane transport of plant hormones and their related compounds is an essential process that determines the distribution of the compounds within plant tissues and, hence, regulates various physiological events. Here, we report that the Arabidopsis NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY 7.3 (NPF7.3) protein functions as a transporter of indole-3-butyric acid (IBA), a precursor of the major endogenous auxin indole-3-acetic acid (IAA). When expressed in yeast, NPF7.3 mediated cellular IBA uptake. Loss-of-function npf7.3 mutants showed defective root gravitropism with reduced IBA levels and auxin responses. Nevertheless, the phenotype was restored by exogenous application of IAA but not by IBA treatment. NPF7.3 was expressed in pericycle cells and the root tip region including root cap cells of primary roots where the IBA-to-IAA conversion occurs. Our findings indicate that NPF7.3-mediated IBA uptake into specific cells is required for the generation of appropriate auxin gradients within root tissues.
PMID: 33219124
New Phytol , IF:8.512 , 2020 Nov doi: 10.1111/nph.17061
Functional analysis of auxin receptor OsTIR1/OsAFB family members in rice grain yield, tillering, plant height, root system, germination, and auxinic herbicide resistance.
Institute of Genetics and Regenerative Biology, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China.; State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China.
Auxin regulates almost every aspect of plant growth and development and is perceived by the TIR1/AFB auxin co-receptor proteins differentially acting in concert with specific Aux/IAA transcriptional repressors. Little is known about the diverse functions of TIR1/AFB family members in species other than Arabidopsis. We created targeted OsTIR1 and OsAFB2-5 mutations in rice using CRISPR/Cas9 genome editing, and functionally characterized the roles of these five members in plant growth and development and auxinic herbicide resistance. Our results demonstrated that functions of OsTIR1/AFB family members are partially redundant in grain yield, tillering, plant height, root system and germination. Ostir1, Osafb2 and Osafb4 mutants exhibited more severe phenotypes than Osafb3 and Osafb5. The Ostir1Osafb2 double mutant displays extremely severe defects in plant development. All five OsTIR1/AFB members interacted with OsIAA1 and OsIAA11 proteins in vivo. Root elongation assay showed that each Ostir1/afb2-5 mutant was resistant to 2,4-D treatment. Notably, only the Osafb4 mutants were strongly resistant to herbicide picloram, suggesting that OsAFB4 is a unique auxin receptor in rice. Our findings demonstrate similarities and specificities of auxin receptor TIR1/AFB proteins in rice, and could offer the opportunity to modify effective herbicide-resistant alleles in agronomically important crops.
PMID: 33135782
Plant Biotechnol J , IF:8.154 , 2020 Nov , V18 (11) : P2304-2315 doi: 10.1111/pbi.13392
Maize BIG GRAIN1 homolog overexpression increases maize grain yield.
Corteva Agriscience, Johnston, IA, USA.
The Zea Mays BIG GRAIN 1 HOMOLOG 1 (ZM-BG1H1) was ectopically expressed in maize. Elite commercial hybrid germplasm was yield tested in diverse field environment locations representing commercial models. Yield was measured in 101 tests across all 4 events, 26 locations over 2 years, for an average yield gain of 355 kg/ha (5.65 bu/ac) above control, with 83% tests broadly showing yield gains (range +2272 kg/ha to -1240 kg/ha), with seven tests gaining more than one metric ton per hectare. Plant and ear height were slightly elevated, and ear and tassel flowering time were delayed one day, but ASI was unchanged, and these traits did not correlate to yield gain. ZM-BG1H1 overexpression is associated with increased ear kernel row number and total ear kernel number and mass, but individual kernels trended slightly smaller and less dense. The ZM-BG1H1 protein is detected in the plasma membrane like rice OS-BG1. Five predominant native ZM-BG1H1 alleles exhibit little structural and expression variation compared to the large increased expression conferred by these ectopic alleles.
PMID: 32356392
Plant Physiol , IF:6.902 , 2020 Nov , V184 (3) : P1219-1220 doi: 10.1104/pp.20.01284
Leaf Position Makes a Difference: The ABCB19 Auxin Transporter Affects Light Perception.
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan david.favero@riken.jp.
PMID: 33139487
Plant Physiol , IF:6.902 , 2020 Nov , V184 (3) : P1549-1562 doi: 10.1104/pp.20.00587
Mediator Subunit MED25 Physically Interacts with PHYTOCHROME INTERACTING FACTOR4 to Regulate Shade-Induced Hypocotyl Elongation in Tomato.
State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Taian, Shandong 271018, China.; State Key Laboratory of Plant Genomics, National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China.; Chinese Academy of Sciences Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China.; State Key Laboratory of Plant Genomics, National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China qzzhai@genetics.ac.cn.
Shade triggers important adaptive responses such as the shade-avoidance syndrome, which enable plants to respond to the depletion of photosynthetically active light. The basic helix-loop-helix transcription factors PHYTOCHROME INTERACTING FACTORS (PIFs) play a key role in the shade-avoidance syndrome network by regulating the biosynthesis of multiple phytohormones and the expression of cell expansion-related genes. Although much has been learned about the regulation of PIFs in response to shade at the protein level, relatively little is known about the PIF-dependent transcriptional regulation of shade-responsive genes. Mediator is an evolutionarily conserved transcriptional coactivator complex that bridges gene-specific transcription factors with the RNA polymerase II (Pol II) machinery to regulate gene transcription. Here, we report that tomato (Solanum lycopersicum) PIF4 plays an important role in shade-induced hypocotyl elongation by regulating the expression of genes that encode auxin biosynthesis and auxin signaling proteins. During this process, Mediator subunit25 (MED25) physically interacts with PIF4 at the promoter regions of PIF4 target genes and also recruits Pol II to induce gene transcription. Thus, MED25 directly bridges the communication between PIF4 and Pol II general transcriptional machinery to regulate shade-induced hypocotyl elongation. Overall, our results reveal a novel role of MED25 in PIF4-mediated transcriptional regulation under shade.
PMID: 32938743
Plant Physiol , IF:6.902 , 2020 Nov , V184 (3) : P1424-1437 doi: 10.1104/pp.20.00536
OsHOX1 and OsHOX28 Redundantly Shape Rice Tiller Angle by Reducing HSFA2D Expression and Auxin Content.
National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.; Hubei Academy of Agricultural Sciences, Food Crops Institute, Hubei Key Laboratory of Food Crop Germplasm and Genetic Improvement, Wuhan 430064, China.; National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China yzxing@mail.hzau.edu.cn.
Tiller angle largely determines plant architecture, which in turn substantially influences crop production by affecting planting density. A recent study revealed that HEAT STRESS TRANSCRIPTION FACTOR2D (HSFA2D) acts upstream of LAZY1 (LA1) to regulate tiller angle establishment in rice (Oryza sativa). However, the mechanisms underlying transcriptional regulation of HSFA2D remain unknown. In this study, two class II homeodomain-Leu zipper genes, OsHOX1 and OsHOX28, were identified as positive regulators of tiller angle by affecting shoot gravitropism. OsHOX1 and OsHOX28 showed strong transcriptional suppressive activity in rice protoplasts and formed intricate self- and mutual-transcriptional negative feedback loops. Moreover, OsHOX1 and OsHOX28 bound to the pseudopalindromic sequence CAAT(C/G)ATTG within the promoter of HSFA2D, thus suppressing its expression. In contrast to HSFA2D and LA1, OsHOX1 and OsHOX28 attenuated lateral auxin transport, thus repressing the expression of WUSCHEL-RELATED HOMEOBOX 6 (WOX6) and WOX11 in the lower side of the shoot base of plants subjected to gravistimulation. Genetic analysis further confirmed that OsHOX1 and OsHOX28 act upstream of HSFA2D Additionally, both OsHOX1 and OsHOX28 inhibit the expression of multiple OsYUCCA genes and decrease auxin biosynthesis. Taken together, these results demonstrated that OsHOX1 and OsHOX28 regulate the local distribution of auxin, and thus tiller angle establishment, through suppression of the HSFA2D-LA1 pathway and reduction of endogenous auxin content. Our finding increases the knowledge concerning fine tuning of tiller angles to optimize plant architecture in rice.
PMID: 32913047
Plant Physiol , IF:6.902 , 2020 Nov , V184 (3) : P1499-1513 doi: 10.1104/pp.20.00689
The Ubiquitin-Specific Protease TNI/UBP14 Functions in Ubiquitin Recycling and Affects Auxin Response.
Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India.; Centre for Cellular and Molecular Biology, Hyderabad 500 007, India.; Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India utpalnath@iisc.ac.in.
The ubiquitin-mediated proteasomal pathway regulates diverse cellular processes in plants by rapidly degrading target proteins, including the repressors of hormone signaling. Though ubiquitin proteases play a key role in this process by cleaving polyubiquitin chains to monomers, their function has not been studied in detail by mutational analysis. Here, we show that mutation in TARANI/UBIQUITIN-SPECIFIC PROTEASE14 (TNI/UBP14) leads to reduced auxin response and widespread auxin-related phenotypic defects in Arabidopsis (Arabidopsis thaliana). In a tni partial loss-of-function mutant that was originally isolated based on altered leaf shape, activity of the auxin-responsive reporters DR5::GUS, DR5::nYFP, and IAA2::GUS was reduced. Genetic interaction studies suggest that TNI is involved in auxin signaling and acts alongside TIR1, ARF7, and AUX1 Map-based cloning identified TNI as UBP14 Inefficient splicing of the mutant TNI transcript resulted in the formation of an inactive UBP14 protein, which led to accumulation of polyubiquitin chains and excess polyubiquitinated proteins in the mutant. In addition to the reduced auxin response, increased levels of DII:VENUS, IAA18:GUS, and HS::AXR3-NT:GUS were also observed in tni, perhaps due to inefficient polyubiquitin hydrolysis and proteasome-mediated degradation. Together, our study identifies a function for TNI/UBP14 in the auxin response through ubiquitin recycling.
PMID: 32859753
Plant Physiol , IF:6.902 , 2020 Nov , V184 (3) : P1601-1612 doi: 10.1104/pp.20.00223
An ATP-Binding Cassette Transporter, ABCB19, Regulates Leaf Position and Morphology during Phototropin1-Mediated Blue Light Responses.
Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20740.; Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20740 asmurphy@umd.edu.
Blue light regulates multiple processes that optimize light capture and gas exchange in plants, including chloroplast movement, changes in stomatal conductance, and altered organ positioning. In Arabidopsis (Arabidopsis thaliana), these processes are primarily modulated by the blue light phototropin photoreceptors phot1 and phot2. Changes in leaf positioning and shape involve several signaling components that include NON-PHOTOTROPIC HYPOCOTYL3, PHYTOCHROME KINASE SUBSTRATE, ROOT PHOTOTROPISM2, and alterations in localized auxin streams. Direct phosphorylation of the auxin transporter ATP-BINDING CASSETTE subfamily B19 (ABCB19) by phot1 in phototropic seedlings suggests that phot1 may directly regulate ABCB19 to adjust auxin-dependent leaf responses. Here, abcb19 mutants were analyzed for fluence and blue light-dependent changes in leaf positioning and morphology. abcb19 displays upright petiole angles that remain unchanged in response to red and blue light. Similarly, abcb19 mutants develop irregularly wavy rosette leaves that are less sensitive to blue light-mediated leaf flattening. Visualization of auxin distribution, measurement of auxin transport in protoplasts, and direct quantification of free auxin levels suggest these irregularities are caused by misregulation of ABCB19-mediated auxin distribution in addition to light-dependent auxin biosynthesis.
PMID: 32855213
Anal Chem , IF:6.785 , 2020 Nov , V92 (21) : P14568-14575 doi: 10.1021/acs.analchem.0c02854
Label-Free and Simultaneous Mechanical and Electrical Characterization of Single Plant Cells Using Microfluidic Impedance Flow Cytometry.
State Key Laboratory of Precision Measuring Technology and Instruments, College of Precision Instrument and Opto-electronics Engineering, Tianjin University, Tianjin 300072, China.; School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China.
Despite that single-cell-type-level analyses have been extensively conducted on animal models to gain new insights into complex biological processes; the unique biological and physiological properties of plant cells have not been widely studied at single-cell resolution. In this work, an electrical impedance flow cytometry was fabricated based on microfluidics with constriction microchannel to simultaneously characterize the mechanical and electrical properties of single plant cells. Protoplasts from two model plant species, the herbaceous Arabidopsis thaliana and the woody Populus trichocarpa, could be readily discriminated by their respective mechanical traits, but not by electrical impedance. On the contrary, overexpression of a red fluorescent protein on plasma membrane resulted in changes in cell electrical impedance instead of cell deformability. During primary cell wall (PCW) regeneration, this extracellular layer outside of protoplasts introduced dramatic variations in both mechanical and electrical properties of single plant cells. Furthermore, the effects of auxin, an essential phytohormone regulating PCW reformation, were validated on this platform. Taken together, our results revealed a novel application of microfluidic impedance flow cytometry in the field of plant science to simultaneously characterize dual biophysical properties at single-cell resolution, which could be further developed as a powerful and reliable tool for plant cell phenotyping and cell fate specification.
PMID: 32911928
Sci Total Environ , IF:6.551 , 2020 Nov , V745 : P141032 doi: 10.1016/j.scitotenv.2020.141032
Enhancing the CO2 capturing ability in leaf via xenobiotic auxin uptake.
Faculty of Science and Technology, Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland; Charles University in Prague, Faculty of Pharmacy in Hradec Kralove, Heyrovskeho 1203, Hradec Kralove 500 05, Czech Republic.; Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, Jagiellonska 28, 40-032 Katowice, Poland.; Faculty of Science and Technology, Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland.; Faculty of Science and Technology, August Chelkowski Institute of Physics, University of Silesia in Katowice, Bankowa 14, 40-007 Katowice, Poland.; Charles University in Prague, Faculty of Pharmacy in Hradec Kralove, Heyrovskeho 1203, Hradec Kralove 500 05, Czech Republic.; Faculty of Science and Technology, Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland. Electronic address: polanski@us.edu.pl.
Plants are masterpieces of evolution that is based on carbon chemistry. In particular, plant leaves are biosynthetic factories able to convert CO2 into carbohydrates and oxygen. It is worth noting that mimicking the efficiency of a natural plant and natural leaf is still a challenge for contemporary chemistry. We can even better realize this when we notice that a plant and an industrial factory are equivalent in meaning. On the other hand, green technologies are under development in a quest for the artificial leaf. If we could modify the synthetic pathways in leaves, we could also design green chemistry schemes in natural leaves to produce useful chemicals or to digest wastes or toxins. Specifically, can we intensify the potential for capturing atmospheric CO2 in leaves? Auxins are plant hormones that control the growth and development of plants. Herein, we determined whether we could efficiently transport xenobiotic auxin into leaves and if so, whether this supply could enhance the metabolism and CO2 capturing ability. By exploring a series of dioxolanes as potential enhancers of auxin transport, we discovered for the first time that a small molecular compound, 2,2-dimethyl-1,3-dioxolane (DMD), enhances the xenobiotic auxin transport to leaves, which boosts the metabolism that is measured by H2O2 production as well as CO2 capturing ability in leaves.
PMID: 32726691
Plant J , IF:6.141 , 2020 Nov doi: 10.1111/tpj.15096
Sensors for quantification, localization and analysis of dynamics of plant hormones.
Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya, 464-8601, Japan.; Molecular Physiology, Heinrich-Heine-University, Dusseldorf, Germany.; Developmental Genetics, Heinrich-Heine-University, Dusseldorf, Germany.
Plant hormones play important roles in plant growth and development, physiology and in acclimation to environmental changes. The hormone signaling networks are highly complex and interconnected. It is thus important to not only know where the hormones are produced, how they are transported and how and where they are perceived, but also to quantitatively monitor their distribution quantitatively, ideally in a non-invasive manner. Here we summarize the diverse set of tools available for quantifying and visualizing hormone distribution and dynamics. We provide an overview over the tools that are currently available - including transcriptional reporters, and degradation sensors, luciferase and fluorescent sensors - and compare the tools and their suitability for different purposes.
PMID: 33231903
Plant J , IF:6.141 , 2020 Nov doi: 10.1111/tpj.15086
The AGCVIII kinase Dw2 modulates cell proliferation, endomembrane trafficking, and MLG/xylan cell wall localization in elongating stem internodes of Sorghum bicolor.
Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas, 77843, USA.; Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA.; Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan, 48824, USA.; MSU-DOE Plant Research Lab, Michigan State University, East Lansing, Michigan, 48824, USA.; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824, USA.
Stems of bioenergy sorghum, a drought tolerant C4 grass, contain up to 50 nodes and internodes of varying length that span 4-5 meters and account for ~84% of harvested biomass. Stem internode growth impacts plant height and biomass accumulation and is regulated by brassinosteroid signaling, auxin transport, and gibberellin biosynthesis. In addition, an AGCVIII kinase (Dw2) regulates sorghum stem internode growth, but the underlying mechanism and signaling network are unknown. Here we provide evidence that mutation of Dw2 reduces cell proliferation in internode intercalary meristems, inhibits endocytosis, and alters the distribution of heteroxylan and mixed linkage glucan in cell walls. Phosphoproteomic analysis showed that Dw2 signaling influences the phosphorylation of proteins involved in lipid signaling (PLDdelta), endomembrane trafficking, hormone, light and receptor signaling, and photosynthesis. Together, our results show that Dw2 modulates endomembrane function and cell division during sorghum internode growth providing insight into the regulation of monocot stem development.
PMID: 33211340
Plant J , IF:6.141 , 2020 Nov , V104 (4) : P1105-1116 doi: 10.1111/tpj.14984
FERONIA mediates root nutating growth.
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, China.; State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
Root nutation indicates the behavior that roots grow in a waving and skewing way due to unequal growth rates on different sides. Although a few developmental and environmental factors have been reported, genetic pathways mediating this process are obscure. We report here that the Arabidopsis CrRLK1L family member FERONIA (FER) is critical for root nutation. Functional loss of FER resulted in enhanced root waviness on tilted plates or roots forming anti-clockwise coils on horizontal plates. Suppressing polar auxin transport, either by pharmacological treatment or by introducing mutations at PIN-FORMED2 (PIN2) or AUXIN RESISTANT1 (AUX1), suppressed the asymmetric root growth (ARG) in fer-4, a null mutant of FER, indicating that FER suppression of ARG depends on polar auxin transport. We further showed by pharmacological treatments that dynamic microtubule organization and Ca(2+) signaling are both critical for FER-mediated ARG. Results presented here demonstrate a key role of FER in mediating root nutating growth, through PIN2- and AUX1-mediated auxin transport, through dynamic microtubule organization, and through Ca(2+) signaling.
PMID: 32891072
Plant J , IF:6.141 , 2020 Nov , V104 (4) : P1023-1037 doi: 10.1111/tpj.14978
Rice plants respond to ammonium stress by adopting a helical root growth pattern.
State Key Laboratory of Crop Genetics and Germplasm Enhancement and MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing, 210095, China.; Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, Ghent, B-9052, Belgium.; VIB-UGent Center for Plant Systems Biology, Technologiepark 71, Ghent, B-9052, Belgium.; Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China.; State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.; Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China.
High levels of ammonium nutrition reduce plant growth and different plant species have developed distinct strategies to maximize ammonium acquisition while alleviating ammonium toxicity through modulating root growth. To date, the mechanisms underlying plant tolerance or sensitivity towards ammonium remain unclear. Rice (Oryza sativa) uses ammonium as its main N source. Here we show that ammonium supply restricts rice root elongation and induces a helical growth pattern, which is attributed to root acidification resulting from ammonium uptake. Ammonium-induced low pH triggers the asymmetric distribution of auxin in rice root tips through changes in auxin signaling, thereby inducing a helical growth response. Blocking auxin signaling completely inhibited this root response. In contrast, this root response is not activated in ammonium-treated Arabidopsis. Acidification of Arabidopsis roots leads to the protonation of indole-3-acetic acid and dampening of the intracellular auxin signaling levels that are required for maintaining root growth. Our study suggests a different mode of action by ammonium on the root pattern and auxin response machinery in rice versus Arabidopsis, and the rice-specific helical root response towards ammonium is an expression of the ability of rice to moderate auxin signaling and root growth to utilize ammonium while confronting acidic stress.
PMID: 32890411
Plant J , IF:6.141 , 2020 Nov , V104 (4) : P1073-1087 doi: 10.1111/tpj.14982
Leaflet initiation and blade expansion are separable in compound leaf development.
State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China.; University of Chinese Academy of Sciences, Beijing, 100049, China.; The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University, PO Box 12, Rehovot, 76100, Israel.; Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 7610001, Israel.
Compound leaves are composed of multiple separate blade units termed leaflets. In tomato (Solanum lycopersicum) compound leaves, auxin promotes both leaflet initiation and blade expansion. However, it is unclear how these two developmental processes interact. With highly variable complexity, tomato compound leaves provide an ideal system to address this question. In this study, we obtained and analyzed mutants of the WUSCHEL-RELATED HOMEOBOX (WOX) family gene SlLAM1 from tomato, whose orthologs in tobacco (Nicotiana sylvestris) and other species are indispensable for blade expansion. We show that SlLAM1 is expressed in the middle and marginal domains of leaves, and is required for blade expansion in leaflets. We demonstrate that sllam1 mutants cause a delay of leaflet initiation and slightly alter the arrangement of first-order leaflets, whereas the overall leaflet number is comparable to that of wild-type leaves. Analysis of the genetic interactions between SlLAM1 and key auxin signaling components revealed an epistatic effect of SlLAM1 in determining the final leaf form. Finally, we show that SlLAM1 is also required for floral organ growth and affects the fertility of gametophytes. Our data suggest that SlLAM1 promotes blade expansion in multiple leaf types, and leaflet initiation can be largely uncoupled from blade expansion during compound leaf morphogenesis.
PMID: 32889762
J Exp Bot , IF:5.908 , 2020 Nov doi: 10.1093/jxb/eraa512
Genome-wide association study reveals glucosyltransferase OsIAGLU regulating root growth in rice.
The Laboratory of Seed Science and Technology, Guangdong Key Laboratory of Plant Molecular Breeding, Guangdong Laboratory of Lingnan Modern Agriculture, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, People's Republic of China.; College of Agriculture and Biology, Zhongkai University of Agriculture and Engineering, Guangzhou, People's Republic of China.; Huzhou Agricultural Science and Technology Development Center, Huzhou, People's Republic of China.; Northeast Agricultural University, Harbin, People's Republic of China.
Root growth at the post-germination stage is an important trait for direct seeding in rice. However, the genetic basis underlying this process is poorly understood. Here, the genetic architecture of variation in primary root length was studied using a diverse panel of 178 accessions in rice. Four QTLs (qRL3, qRL6, qRL7, and qRL11) for root length were identified using genome-wide association studies. One candidate gene, glucosyltransferase OsIAGLU for the novel major QTL qRL11, was validated in rice. Disruption of OsIAGLU reduced the primary root length and the number of lateral and crown roots. The natural allelic variations of OsIAGLU contributing to root growth were identified in rice. Functional analysis revealed that OsIAGLU regulated root growth mainly via modulating multiple hormones including auxin, jasmonic acid, abscisic acid, and cytokinin levels in roots. In addition, OsIAGLU influenced expression of multiple hormone-related genes associated with root growth. Overall, we identified that the glucosyltransferase OsIAGLU regulated root growth through multiple hormone pathways. The OsIAGLU contributing to natural variation of root length could be used to facilitate the future rice breeding.
PMID: 33130882
Development , IF:5.611 , 2020 Nov doi: 10.1242/dev.196618
Asynchrony of ovule primordia initiation in Arabidopsis.
Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Joint Center for Sing Cell Biology, Shanghai Jiao Tong University, Shanghai 200240, China.; Faculty of Mechanical Engineering and Mechanics, Ningbo University, Ningbo, Zhejiang, 315211, China.; State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and National Center for Plant Gene Research, Beijing 100101, China.; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.; National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.; Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Joint Center for Sing Cell Biology, Shanghai Jiao Tong University, Shanghai 200240, China whlin@sjtu.edu.cn.
Plant ovule initiation determines the maximum of ovule number and has a great impact on the seed number per fruit. The detailed processes of ovule initiation have not been accurately described although two connected processes, gynoecium and ovule development, have been investigated. Here we report that ovules initiate asynchronously. The first group of ovule primordia grows out, the placenta elongate, the boundaries of existing ovules enlarge and new group of primordia initiates from the boundaries. The expression pattern of different marker genes during ovule development illustrates that this asynchronicity continues throughout whole ovule development. PIN-FORMED1 polar distribution and auxin response maxima correlate to ovule primordia initiation asynchronous. We established computational modeling to show how auxin dynamics influence ovule primordia initiation. Brassinosteroid signaling positively regulates ovule number by promoting placentae size and ovule primordia initiation through strengthening auxin response. Transcriptomic analysis demonstrates numerous known regulators of ovule development and hormones signaling, and many new genes are identified to involve in ovule development. Taken together, our results illustrate the ovule primordia initiate asynchronously and the hormone signal involve in the asynchrony.
PMID: 33234714
Development , IF:5.611 , 2020 Nov doi: 10.1242/dev.190033
Conserved LBL1-ta-siRNA and miR165/166-RLD1/2 modules regulate root development in maize.
National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India.; Centre of Experimental Medicine and Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India.; Department of Botany and Forestry, Vidyasagar University, Midnapore, West Bengal 721104 India.; National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India aksarkar@nipgr.ac.in.
Root system architecture and anatomy of monocotyledonous maize is significantly different from dicotyledonous model Arabidopsis The molecular role of non-coding RNA (ncRNA) is poorly understood in maize root development. Here we address the role of LEAFBLADELESS1 (LBL1), a component of maize trans-acting short-interfering RNA (ta-siRNA), in maize root development. We report that the root growth, anatomical patterning, number of lateral roots (LRs) and monocot-specific crown roots (CRs) and seminal roots (SRs) are significantly affected in lbl1-rgd1 mutant, which is defective in production of ta-siRNA, including tasiR-ARF that targets AUXIN RESPONSE FACTOR3 (ARF3) in maize. Altered accumulation and distribution of auxin, due to differential expression of auxin biosynthesis and transporter genes, created an imbalance in auxin signaling. Altered expression of microRNA165/166 (miR165/166) and its targets ROLLED1/2 (RLD1/2) contributed to the changes in lbl1-rgd1 root growth and vascular patterning, as was evident by altered root phenotype of Rld1-O semi-dominant mutant. Thus, LBL1/ta-siRNA module regulates root development, possibly by affecting auxin distribution and signaling, in crosstalk with miR165/166-RLD1/2 module. We further showed that ZmLBL1 and its Arabidopsis homolog AtSGS3 proteins are functionally conserved.
PMID: 33168582
Development , IF:5.611 , 2020 Nov doi: 10.1242/dev.192625
HY5 and phytochrome activity modulate shoot to root coordination during thermomorphogenesis.
Plant Biology Laboratory, Salk Institute for Biological Studies, 10010 N Torrey Pines Rd, La Jolla, CA 92037, USA.; Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.; Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umea, Sweden.; Department of Biosciences College of Life and Environmental Sciences, Stocker Road, Exeter EX4 4QD, UK.; Plant Biology Laboratory, Salk Institute for Biological Studies, 10010 N Torrey Pines Rd, La Jolla, CA 92037, USA wbusch@salk.edu.; Integrative Biology Laboratory, Salk Institute for Biological Studies, 10010 N Torrey Pines Rd, La Jolla, CA 92037, USA.
Temperature is one of the most impactful environmental factors to which plants adjust their growth and development. While the regulation of temperature signaling has been extensively investigated for the aerial part of plants, much less is known and understood about how roots sense and modulate their growth in response to fluctuating temperatures. Here we found that shoot and root growth responses to high ambient temperature are coordinated during early seedling development. A shoot signaling module that includes HY5, the phytochromes and the PIFs exerts a central function in coupling these growth responses and maintain auxin levels in the root. In addition to the HY5/PIF-dependent shoot module, a regulatory axis composed of auxin biosynthesis and auxin perception factors controls root responses to high ambient temperature. Together, our findings show that shoot and root developmental responses to temperature are tightly coupled during thermomorphogenesis and suggest that roots integrate energy signals with local hormonal inputs.
PMID: 33144393
FASEB J , IF:4.966 , 2020 Nov , V34 (11) : P15547-15558 doi: 10.1096/fj.202001523R
Npa3 interacts with Gpn3 and assembly factor Rba50 for RNA polymerase II biogenesis.
College of Life Sciences, Hebei Agricultural University, Baoding, China.; State Key Laboratory of North China Crop Improvement and Regulation, Baoding, China.; Peking-Tsinghua Center for Life Sciences, The National Laboratory of Protein and Plant Gene Research, The College of Life Sciences, Peking University, Beijing, China.
RNA polymerase II is one of the most vital macromolecular complexes in eukaryotes and the assembly of such complete enzyme requires many factors. Three members of GPN-loop GTPase family Npa3/Gpn1, Gpn2, and Gpn3 participate in the biogenesis of RNA polymerase II with nonredundant roles. We show here that rapid degradation of each GPN protein in yeast leads to cytoplasmic accumulation of Rpb1 and defects in the assembly of RNA polymerase II, suggesting conserved functions of GPN paralogs for RNA polymerase II biogenesis as in humans. Taking advantage of a multicopy genetic screening, we identified GPN3 and assembly factor RBA50 among others as strong suppressors of npa3(ts) mutants. We further demonstrated that Npa3 interacts with Gpn3 and Rba50, similarly human Gpn1 physically interacts with Gpn3 and RPAP1 (human analog of Rba50). Moreover, a mutual dependency of protein levels of Npa3 and Gpn3 was also clearly presented in yeast using an auxin-inducible degron (AID) system. Interestingly, Rpb2, the second largest subunit of RNA polymerase II was determined to be the subunit that interacts with both Gpn1 and Rba50, indicating a close association of Npa3 and Rba50 in Rpb2 subcomplex assembly. Based on these results, we conclude that Npa3 interacts with Gpn3 and Rba50, for RNA polymerase II biogenesis. We therefore propose that multiple factors may coordinate through conserved regulatory mechanisms in the assembly of RNA polymerase complex.
PMID: 32985767
J Integr Plant Biol , IF:4.885 , 2020 Nov doi: 10.1111/jipb.13036
Light participates in the auxin-dependent regulation of plant growth.
The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, College of Life Sciences, Shandong University, Qingdao, 266237, China.; State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China.
Light is the energy source for plant photosynthesis and influences plant growth and development. Through multiple photoreceptors, plant interprets light signals through various downstream phytohormones such as auxin. Recently, Chen et al. (2020) uncover a new layer of regulation in IPyA pathway of auxin biosynthesis by light. Here we highlight recent studies about how light controls plant growth through regulating auxin biosynthesis and signaling. This article is protected by copyright. All rights reserved.
PMID: 33215867
Int J Mol Sci , IF:4.556 , 2020 Nov , V21 (22) doi: 10.3390/ijms21228857
Transcriptome Analysis of Pyrus betulaefolia Seedling Root Responses to Short-Term Potassium Deficiency.
Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-Saving Fertilizers, Nanjing Agricultural University, Nanjing 210095, China.; College of Life Science, Hubei Engineering University, Xiaogan 432100, China.; School of Resources and Environmental Sciences, Henan Institute of Science and Technology, Xinxiang 453003, China.; Department of Horticulture, 1111 Miller Plant Sciences, University of Georgia, Athens, GA 30602, USA.
Potassium (K) plays a crucial role in multiple physiological and developmental processes in plants. Its deficiency is a common abiotic stress that inhibits plant growth and reduces crop productivity. A better understanding of the mechanisms involved in plant responses to low K could help to improve the efficiency of K use in plants. However, such responses remain poorly characterized in fruit tree species such as pears (Pyrus sp). We analyzed the physiological and transcriptome responses of a commonly used pear rootstock, Pyrus betulaefolia, to K-deficiency stress (0 mM). Potassium deprivation resulted in apparent changes in root morphology, with short-term low-K stress resulting in rapidly enhanced root growth. Transcriptome analyses indicated that the root transcriptome was coordinately altered within 6 h after K deprivation, a process that continued until 15 d after treatment. Potassium deprivation resulted in the enhanced expression (up to 5-fold) of a putative high-affinity K(+) transporter, PbHAK5 (Pbr037826.1), suggesting the up-regulation of mechanisms associated with K(+) acquisition. The enhanced root growth in response to K-deficiency stress was associated with a rapid and sustained decrease in the expression of a transcription factor, PbMYB44 (Pbr015309.1), potentially involved in mediating auxin responses, and the increased expression of multiple genes associated with regulating root growth. The concentrations of several phytohormones including indoleacetic acid (IAA), ABA, ETH, gibberellin (GA3), and jasmonic acid (JA) were higher in response to K deprivation. Furthermore, genes coding for enzymes associated with carbon metabolism such as SORBITOL DEHYDROGENASE (SDH) and SUCROSE SYNTHASE (SUS) displayed greatly enhanced expression in the roots under K deprivation, presumably indicating enhanced metabolism to meet the increased energy demands for growth and K(+) acquisition. Together, these data suggest that K deprivation in P. betulaefolia results in the rapid re-programming of the transcriptome to enhance root growth and K(+) acquisition. These data provide key insights into the molecular basis for understanding low-K-tolerance mechanisms in pears and in other related fruit trees and identifying potential candidates that warrant further analyses.
PMID: 33238495
Int J Mol Sci , IF:4.556 , 2020 Nov , V21 (22) doi: 10.3390/ijms21228742
MtPIN1 and MtPIN3 Play Dual Roles in Regulation of Shade Avoidance Response under Different Environments in Medicago truncatula.
The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Science, Shandong University, Qingdao 266237, China.; School of Life Science, Guangzhou University, Guangzhou 510006, China.; State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China.; Hunan Provincial Key Laboratory of Phytohormones, Hunan Agricultural University, Changsha 410128, China.; Grassland Agri-Husbandry Research Center, Qingdao Agricultural University, Qingdao 266109, China.; Noble Research Institute, LLC, Ardmore, OK 73401, USA.
Polar auxin transport mediated by PIN-FORMED (PIN) proteins is critical for plant growth and development. As an environmental cue, shade stimulates hypocotyls, petiole, and stem elongation by inducing auxin synthesis and asymmetric distributions, which is modulated by PIN3,4,7 in Arabidopsis. Here, we characterize the MtPIN1 and MtPIN3, which are the orthologs of PIN3,4,7, in model legume species Medicago truncatula. Under the low Red:Far-Red (R:FR) ratio light, the expression of MtPIN1 and MtPIN3 is induced, and shadeavoidance response is disrupted in mtpin1 mtpin3 double mutant, indicating that MtPIN1 and MtPIN3 have a conserved function in shade response. Surprisingly, under the normal growth condition, mtpin1 mtpin3 displayed the constitutive shade avoidance responses, such as the elongated petiole, smaller leaf, and increased auxin and chlorophyll content. Therefore, MtPIN1 and MtPIN3 play dual roles in regulation of shadeavoidance response under different environments. Furthermore, these data suggest that PIN3,4,7 and its orthologs have evolved conserved and specific functions among species.
PMID: 33228084
Int J Mol Sci , IF:4.556 , 2020 Nov , V21 (22) doi: 10.3390/ijms21228441
Aux/IAA14 Regulates microRNA-Mediated Cold Stress Response in Arabidopsis Roots.
Department of Plant Bio Sciences, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan.; State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Key Lab of Sugarcane Biology, College of Agriculture, Guangxi University, Nanning 530004, China.; Key Laboratory of Genetics, Breeding and Multiple Utilization of Crops, Ministry of Education, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Center for Genomics and Biotechnology, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou 350002, China.; United Graduate School of Agricultural Sciences, Iwate University, Morioka 020-8550, Japan.; Agri-Innovation Center, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan.
The phytohormone auxin and microRNA-mediated regulation of gene expressions are key regulators of plant growth and development at both optimal and under low-temperature stress conditions. However, the mechanistic link between microRNA and auxin in regulating plant cold stress response remains elusive. To better understand the role of microRNA (miR) in the crosstalk between auxin and cold stress responses, we took advantage of the mutants of Arabidopsis thaliana with altered response to auxin transport and signal. Screening of the mutants for root growth recovery after cold stress at 4 degrees C revealed that the auxin signaling mutant, solitary root 1 (slr1; mutation in Aux/IAA14), shows a hypersensitive response to cold stress. Genome-wide expression analysis of miRs in the wild-type and slr1 mutant roots using next-generation sequencing revealed 180 known and 71 novel cold-responsive microRNAs. Cold stress also increased the abundance of 26-31 nt small RNA population in slr1 compared with wild type. Comparative analysis of microRNA expression shows significant differential expression of 13 known and 7 novel miRs in slr1 at 4 degrees C compared with wild type. Target gene expression analysis of the members from one potential candidate miR, miR169, revealed the possible involvement of miR169/NF-YA module in the Aux/IAA14-mediated cold stress response. Taken together, these results indicate that SLR/IAA14, a transcriptional repressor of auxin signaling, plays a crucial role in integrating miRs in auxin and cold responses.
PMID: 33182739
Front Plant Sci , IF:4.402 , 2020 , V11 : P581983 doi: 10.3389/fpls.2020.581983
Auxin Directly Upregulates GhRAC13 Expression to Promote the Onset of Secondary Cell Wall Deposition in Cotton Fibers.
Biotechnology Research Center, Southwest University, Chongqing, China.; Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Southwest University, Chongqing, China.
Cotton fibers are single cells that show a relatively independent developmental process of cell differentiation, elongation, and secondary wall deposition. Auxin promotes fiber cell protrusion from the surface of the ovule. However, the role of auxin at other stages of cotton fiber development remains largely unknown. To gain a deeper insight into this aspect, we measured indoleacetic acid (IAA) content in developing fibers. Results showed an increase in IAA content at the transition stage from elongation to secondary cell wall deposition. Subsequently, we investigated the differences between two transgenic cottons that show upregulated and downregulated fiber auxin levels, respectively. In planta analysis revealed that, in addition to promoting cell elongation, auxin regulated the time of initiation of reactive oxygen species (ROS) production and secondary wall deposition in cotton fibers. This was closely correlated with the upregulated expression of GhRAC13, which regulates ROS-triggered cellulose synthesis. We found multiple putative auxin-responsive elements existed within the promoter region of GhRAC13, and IAA could induce proGhRAC13 activity. The dual-luciferase reporter assay further proved the activation of proGhRAC13 by GhARF5, an auxin-signaling activator. Altogether, our results suggest a role of auxin in promoting the onset of secondary growth by directly upregulating GhRAC13 expression in cotton fibers.
PMID: 33224170
Front Plant Sci , IF:4.402 , 2020 , V11 : P567388 doi: 10.3389/fpls.2020.567388
A Microbial-Based Biostimulant Enhances Sweet Pepper Performance by Metabolic Reprogramming of Phytohormone Profile and Secondary Metabolism.
Next Generation Agronomics Laboratory (NGAlab), La Riera de Gaia, Tarragona, Spain.; Department of Agricultural Sciences, University of Naples Federico II, Portici, Italy.; Department for Sustainable Food Process, Research Centre for Nutrigenomics and Proteomics, Universita Cattolica del Sacro Cuore, Piacenza, Italy.; Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro di ricerca Orticoltura e Florovivaismo, Pontecagnano Faiano, Italy.; Atens, La Riera de Gaia, Tarragona, Spain.; Department of Agriculture and Forest Sciences, Universita degli Studi della Tuscia, Viterbo, Italy.
Microbial-based biostimulants can improve crop productivity by modulating cell metabolic pathways including hormonal balance. However, little is known about the microbial-mediated molecular changes causing yield increase. The present study elucidates the metabolomic modulation occurring in pepper (Capsicum annuum L.) leaves at the vegetative and reproductive phenological stages, in response to microbial-based biostimulants. The arbuscular mycorrhizal fungi Rhizoglomus irregularis and Funneliformis mosseae, as well as Trichoderma koningii, were used in this work. The application of endophytic fungi significantly increased total fruit yield by 23.7% compared to that of untreated plants. Multivariate statistics indicated that the biostimulant treatment substantially altered the shape of the metabolic profile of pepper. Compared to the untreated control, the plants treated with microbial biostimulants presented with modified gibberellin, auxin, and cytokinin patterns. The biostimulant treatment also induced secondary metabolism and caused carotenoids, saponins, and phenolic compounds to accumulate in the plants. Differential metabolomic signatures indicated diverse and concerted biochemical responses in the plants following the colonization of their roots by beneficial microorganisms. The above findings demonstrated a clear link between microbial-mediated yield increase and a strong up-regulation of hormonal and secondary metabolic pathways associated with growth stimulation and crop defense to environmental stresses.
PMID: 33224160
Front Microbiol , IF:4.235 , 2020 , V11 : P587005 doi: 10.3389/fmicb.2020.587005
Chimeric Tobamoviruses With Coat Protein Exchanges Modulate Symptom Expression and Defence Responses in Nicotiana tabacum.
Liaoning Key Laboratory of Plant Pathology, College of Plant Protection, Shenyang Agricultural University, Shenyang, China.; Sichuan Tobacco Company Deyang City Company, Deyang, China.
In the pathogen infection and host defence equilibrium, plant viruses have evolved to efficiently replicate their genomes, to resist the attack from host defence responses and to avoid causing severe negative effect on growth and metabolism of the hosts. In this study, we generated chimeric tobacco mosaic virus (TMV) variants, in which the coat protein (CP) sequences were substituted with that of cucumber green mottle mosaic virus (CGMMV) or pepper mild mottle virus (PMMoV) to address the role of these in virus infection and host symptomology. The results showed that the chimeric viruses (TMV-CGCP or TMV-PMCP) induce stunting and necrotic symptoms in tobacco plants. We analyzed the transcriptomic changes in tobacco plants after infection of TMV and its chimeras using a high-throughput RNA sequencing approach and found that infection of the chimeric TMV induced significant up-regulation of host defence responsive genes together with salicylic (SA) or abscisic acid (ABA) responsive genes, but down-regulation of auxin (Aux) responsive genes. We further confirmed the increase in the levels of SA and ABA, together with the reduced levels of Aux after infection of chimeric TMV in tobacco plants. These data suggest novel roles of tobamovirus CP in induction of host symptoms and defence responses.
PMID: 33240243
Physiol Plant , IF:4.148 , 2020 Nov doi: 10.1111/ppl.13262
Phytomelatonin: An overview of the importance and mediating functions of melatonin against environmental stresses.
School of Life and Pharmaceutical Sciences, Hainan University, Haikou, China.; School of Economics, Hainan University, Haikou, China.; Center for Terrestrial Biodiversity of the South China Sea, College of Ecology and Environment, Hainan University, Haikou, China.; Institute of Biological Sciences, University of Talca, Talca, Chile.; Department of Plant Biology (Plant Physiology), Faculty of Biology, University of Murcia, Murcia, Spain.; Department of Horticulture, Faculty of Agricultural Science and Technology, Bahauddin Zakariya University, Multan, Pakistan.; College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China.; College of Ecology and Environment, Hainan University, Haikou, China.; Institute for Clinical Chemistry, University Medical Center Goettingen, Goettingen, Germany.; Department of Environment and Soil Sciences, University of Lleida, Lleida, Spain.; College of Horticulture and Forestry Sciences, Huazhong Agricultural University/Key Laboratory of Horticultural Plant Biology, Ministry of Education, Wuhan, China.; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China.; Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.; Department of Life Sciences, National University of Kaohsiung, Kaohsiung, Taiwan.
Recently, melatonin has gained significant importance in plant research. The presence of melatonin in the plant kingdom has been known since 1995. It is a molecule that is conserved in a wide array of evolutionary distant organisms. Its functions and characteristics have been found to be similar in both plants and animals. The review focuses on the role of melatonin pertaining to physiological functions in higher plants. Melatonin regulates physiological functions regarding auxin activity, root, shoot, and explant growth, activates germination of seeds, promotes rhizogenesis (growth of adventitious and lateral roots), and holds up impelled leaf senescence. Melatonin is a natural bio-stimulant that creates resistance in field crops against various abiotic stress, including heat, chemical pollutants, cold, drought, salinity, and harmful ultra-violet radiation. The full potential of melatonin in regulating physiological functions in higher plants still needs to be explored by further research.
PMID: 33159319
Biomolecules , IF:4.082 , 2020 Nov , V10 (11) doi: 10.3390/biom10111550
Glutathione Enhances Auxin Sensitivity in Arabidopsis Roots.
Institute of Biology II/Molecular Plant Physiology, Centre for BioSystems Analysis, BIOSS Centre for Biological Signalling Studies University of Freiburg, 79104 Freiburg, Germany.; Department of Food Science, Aarhus University, 8200 Aarhus N, Denmark.
Root development is regulated by the tripeptide glutathione (GSH), a strong non-enzymatic antioxidant found in plants but with a poorly understood function in roots. Here, Arabidopsis mutants deficient in GSH biosynthesis (cad2, rax1, and rml1) and plants treated with the GSH biosynthesis inhibitor buthionine sulfoximine (BSO) showed root growth inhibition, significant alterations in the root apical meristem (RAM) structure (length and cell division), and defects in lateral root formation. Investigation of the molecular mechanisms of GSH action showed that GSH deficiency modulated total ubiquitination of proteins and inhibited the auxin-related, ubiquitination-dependent degradation of Aux/IAA proteins and the transcriptional activation of early auxin-responsive genes. However, the DR5 auxin transcriptional response differed in root apical meristem (RAM) and pericycle cells. The RAM DR5 signal was increased due to the up-regulation of the auxin biosynthesis TAA1 protein and down-regulation of PIN4 and PIN2, which can act as auxin sinks in the root tip. The transcription auxin response (the DR5 signal and expression of auxin responsive genes) in isolated roots, induced by a low (0.1 microM) auxin concentration, was blocked following GSH depletion of the roots by BSO treatment. A higher auxin concentration (0.5 microM) offset this GSH deficiency effect on DR5 expression, indicating that GSH deficiency does not completely block the transcriptional auxin response, but decreases its sensitivity. The ROS regulation of GSH, the active GSH role in cell proliferation, and GSH cross-talk with auxin assume a potential role for GSH in the modulation of root architecture under stress conditions.
PMID: 33202956
Sci Rep , IF:3.998 , 2020 Nov , V10 (1) : P18913 doi: 10.1038/s41598-020-75421-x
Analysis of a radiation-induced dwarf mutant of a warm-season turf grass reveals potential mechanisms involved in the dwarfing mutant.
Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China.; Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China. mlchai@zju.edu.cn.; Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China. qiaomeiw@zju.edu.cn.; Plant Biotechnology Resource and Outreach Center, Department of Horticulture, Michigan State University, East Lansing, MI, 48824, USA. songg@msu.edu.
Zoysia matrella [L.] Merr. is a widely cultivated warm-season turf grass in subtropical and tropical areas. Dwarf varieties of Z. matrella are attractive to growers because they often reduce lawn mowing frequencies. In this study, we describe a dwarf mutant of Z. matrella induced from the (60)Co-gamma-irradiated calluses. We conducted morphological test and physiological, biochemical and transcriptional analyses to reveal the dwarfing mechanism in the mutant. Phenotypically, the dwarf mutant showed shorter stems, wider leaves, lower canopy height, and a darker green color than the wild type (WT) control under the greenhouse conditions. Physiologically, we found that the phenotypic changes of the dwarf mutant were associated with the physiological responses in catalase, guaiacol peroxidase, superoxide dismutase, soluble protein, lignin, chlorophyll, and electric conductivity. Of the four endogenous hormones measured in leaves, both indole-3-acetic acid and abscisic acid contents were decreased in the mutant, whereas the contents of gibberellin and brassinosteroid showed no difference between the mutant and the WT control. A transcriptomic comparison between the dwarf mutant and the WT leaves revealed 360 differentially-expressed genes (DEGs), including 62 up-regulated and 298 down-regulated unigenes. The major DEGs related to auxin transportation (e.g., PIN-FORMED1) and cell wall development (i.e., CELLULOSE SYNTHASE1) and expansin homologous genes were all down-regulated, indicating their potential contribution to the phenotypic changes observed in the dwarf mutant. Overall, the results provide information to facilitate a better understanding of the dwarfing mechanism in grasses at physiological and transcript levels. In addition, the results suggest that manipulation of auxin biosynthetic pathway genes can be an effective approach for dwarfing breeding of turf grasses.
PMID: 33144613
Rice (N Y) , IF:3.912 , 2020 Nov , V13 (1) : P78 doi: 10.1186/s12284-020-00438-9
Auxin, Abscisic Acid and Jasmonate Are the Central Players in Rice Sheath Rot Caused by Sarocladium oryzae and Pseudomonas fuscovaginae.
Department of Plants and Crops, Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium.; Laboratory of Applied Mycology and Phenomics, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Valentin Vaerwyckweg 1, B-9000, Ghent, Belgium.; Department of Green Chemistry and Technology, Research Group EnVOC, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium.; Department of Plants and Crops, Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium. monica.hofte@ugent.be.
Sheath rot is an emerging rice disease that causes severe yield losses worldwide. The main causal agents are the toxin producers Sarocladium oryzae and Pseudomonas fuscovaginae. The fungus S. oryzae produces helvolic acid and cerulenin and the bacterium P. fuscovaginae produces cyclic lipopeptides. Helvolic acid and the lipopeptide, fuscopeptin, inhibit membrane-bound H(+)-ATPase pumps in the rice plant. To manage rice sheath rot, a better understanding of the host response and virulence strategies of the pathogens is required. This study investigated the interaction of the sheath rot pathogens with their host and the role of their toxins herein. Japonica rice was inoculated with high- and low-helvolic acid-producing S. oryzae isolates or with P. fuscovaginae wild type and fuscopeptin mutant strains. During infection, cerulenin, helvolic acid and the phytohormones abscisic acid, jasmonate, auxin and salicylic acid were quantified in the sheath. In addition, disease severity and grain yield parameters were assessed. Rice plants responded to high-toxin-producing S. oryzae and P. fuscovaginae strains with an increase in abscisic acid, jasmonate and auxin levels. We conclude that, for both pathogens, toxins play a core role during sheath rot infection. S. oryzae and P. fuscovaginae interact with their host in a similar way. This may explain why both sheath rot pathogens cause very similar symptoms despite their different nature.
PMID: 33242152
Plant Cell Rep , IF:3.825 , 2020 Nov doi: 10.1007/s00299-020-02615-y
LhGST is an anthocyanin-related glutathione S-transferase gene in Asiatic hybrid lilies (Lilium spp.).
Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.; Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China. mingjun@caas.cn.
KEY MESSAGE: LhGST, an anthocyanin-related GST gene, was identified from Asiatic hybrid lilies. Expression and functional analyses demonstrated that LhGST might be involved in anthocyanin sequestration in lily tepals. Anthocyanins are responsible for the pink, red and purple pigmentation of flowers in Asiatic hybrid lilies, synthesized at the cytoplasmic surface of the endoplasmic reticulum (ER) and then transported to the vacuole. To date, the mechanism involved in the intracellular transport of anthocyanins in lilies has not been well elucidated. Here, full-length glutathione S-transferase gene (LhGST) was identified from lilies. Expression analysis revealed that LhGST was positively correlated with anthocyanin accumulation. Phylogenetic tree analysis showed that LhGST clustered with other anthocyanin-related GSTs in the same phi clade. Moreover, functional complementation of an Arabidopsis tt19 mutant demonstrated that LhGST might be involved in anthocyanin accumulation in lily tepals. Additionally, according to phenotype analysis, LhGST was found to be correlated with the transport of anthocyanin in lilies by virus-induced gene silencing (VIGS) assay. In addition, cis-element analysis of the LhGST promoter showed the presence of ABA-, auxin-, MeJA-, gibberellin-, light-, and stress-responsive elements and an MYB recognition site (MRS, CCGTTG). Yeast one-hybrid and dual-luciferase report assays revealed that the promoter of LhGST was activated by LhMYB12-lat, which is a key R2R3-MYB transcription factor that regulates anthocyanin biosynthesis in lilies. In conclusion, our results revealed that LhGST plays a key role in anthocyanin transport and accumulation in the tepals of lilies.
PMID: 33210154
Plant Cell Rep , IF:3.825 , 2020 Nov doi: 10.1007/s00299-020-02633-w
ARF4 regulates shoot regeneration through coordination with ARF5 and IAA12.
State Key Laboratory of Crop Biology, College of Life Sciences, College of Forestry, State Forestry and Grassland Administration Key Laboratory of Silviculture in Downstream Areas of the Yellow River, Shandong Agricultural University, Tai'an, 271018, Shandong, China.; State Key Laboratory of Crop Biology, College of Life Sciences, College of Forestry, State Forestry and Grassland Administration Key Laboratory of Silviculture in Downstream Areas of the Yellow River, Shandong Agricultural University, Tai'an, 271018, Shandong, China. sangyl@sdau.edu.cn.; State Key Laboratory of Crop Biology, College of Life Sciences, College of Forestry, State Forestry and Grassland Administration Key Laboratory of Silviculture in Downstream Areas of the Yellow River, Shandong Agricultural University, Tai'an, 271018, Shandong, China. chengzj@sdau.edu.cn.
KEY MESSAGE: ARF4-regulated shoot regeneration through competing with ARF5 for the interaction with IAA12. Plant possess the ability to regenerate shoot meristem and subsequent the whole individual. This process is the foundation for in vitro propagation and genetic engineering and provides a system for studying fundamental biological questions, such as hormonal signaling. Auxin response factor (ARF) family transcription factors are critical components of auxin signaling pathway that regulate the transcription of target genes. To date, the mechanisms underlying the functions of class-B ARFs which act as transcription repressors remains unclear. In this study, we found that ARF4, the transcriptional repressor, was involved in regulating shoot regeneration. ARF4 interacted with auxin/Indole-3-Acetic-Acid12 (IAA12). The expression signals of ARF4 displayed a dynamic pattern similar with those of ARF5 and IAA12 during shoot meristem formation. Enhanced expression of IAA12 compromised the shoot regeneration capacity. Induced expression of ARF4 complemented the regeneration phenotype of IAA12-overexpression but did not rescued the defects in the arf5 mutant, mp-S319. Further analysis revealed that ARF4 competed with ARF5 for the interaction with IAA12. The results indicate that ARF4-regulated shoot regeneration through cooperating with ARF5 and IAA12. Our findings provided new information for deciphering the function of class-B ARFs.
PMID: 33180161
Plant Cell Rep , IF:3.825 , 2020 Nov doi: 10.1007/s00299-020-02631-y
Seed-specific expression of TaYUC10 significantly increases auxin and protein content in wheat seeds.
State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, China.; State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, 271018, China. dsfeng@sdau.edu.cn.
KEY MESSAGE: Present study revealed that specific expression of TaYUC10.3 in wheat young seeds could increase the content of auxin, and protein. Auxin is a vital endogenous hormone in plants, which is involved in the regulation of various physiological and biochemical processes in plants. The flavin-containing monooxygenase encoded by the YUCCA gene is a rate-limiting enzyme in the tryptophan-dependent pathway of auxin synthesis. TaYUC10.3 was identified, cloned and found that it was abundantly expressed in wheat young seeds. In this study, a seed-specific expression vector of TaYUC10.3 was constructed with the promoter of 1Bx17 glutenin subunit gene and transformed wheat using the particle bombardment method. The quantitative RT-PCR showed that TaYUC10.3 was expressed in a large amount in young seeds of the transgenic lines. Plant hormone-targeted metabolomics showed that the auxin content of the transgenic lines was significantly increased compared with controls. The GC / MS non-targeted metabolite multiple statistical analyses showed that the variable importance in projection (VIP) of tryptophan reduced in the transgenic lines. Simultaneously, the VIP of indole acetic acid increased. The precursor amino acids for synthesizing some proteins and carbohydrates were upregulated in the transgenic lines. Subsequently, it was found that the protein content of the seeds of the transgenic TaYUC10.3 wheat was significantly higher than that of the control. The wet gluten content and sedimentation value of the transgenic TaYUC10.3 wheat were also high. This result indicated that TaYUC10.3 might participate in auxin synthesis and affects the protein content of wheat seeds.
PMID: 33179162
Plant Cell Rep , IF:3.825 , 2020 Nov , V39 (11) : P1395-1413 doi: 10.1007/s00299-020-02571-7
Early nodulin 93 protein gene: essential for induction of somatic embryogenesis in oil palm.
Advanced Biotechnology and Breeding Centre, Malaysian Palm Oil Board (MPOB), No. 6, Persiaran Institusi, Bandar Baru Bangi, 43000, Kajang, Selangor, Malaysia. chanpl@mpob.gov.my.; School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia. chanpl@mpob.gov.my.; School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW, 2308, Australia.; School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia.; Advanced Biotechnology and Breeding Centre, Malaysian Palm Oil Board (MPOB), No. 6, Persiaran Institusi, Bandar Baru Bangi, 43000, Kajang, Selangor, Malaysia.; Institute of Plant Biology, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei, 10617, Taiwan, ROC.; , No.16, Jalan 3/5E, 43650, Bandar Baru Bangi, Selangor, Malaysia.; Sime Darby Biotech Laboratories Sdn Bhd., Km10, Jalan Banting-Kelanang, P.O. Box 207, 42700, Banting, Selangor, Malaysia.; , Taman Alam Shah, 41000, Klang, Selangor, Malaysia.; School of Agronomy, Anhui Agricultural University, Hefei, China.
KEY MESSAGE: Transcript profiling during the early induction phase of oil palm tissue culture and RNAi studies in a model somatic embryogenesis system showed that EgENOD93 expression is essential for somatic embryogenesis. Micropropagation of oil palm through tissue culture is vital for the generation of superior and uniform elite planting materials. Studies were carried out to identify genes to distinguish between leaf explants with the potential to develop into embryogenic or non-embryogenic callus. Oil palm cDNA microarrays were co-hybridized with cDNA probes of reference tissue, separately with embryo forming (media T527) and non-embryo (media T694) forming leaf explants sampled at Day 7, Day 14 and Day 21. Analysis of the normalized datasets has identified 77, 115 and 127 significantly differentially expressed genes at Day 7, Day 14, and Day 21, respectively. An early nodulin 93 protein gene (ENOD93), was highly expressed at Day 7, Day 14, and Day 21 and in callus (media T527), as assessed by RT-qPCR. Validation of EgENOD93 across tissue culture lines of different genetic background and media composition showed the potential of this gene as an embryogenic marker. In situ RNA hybridization and functional characterization in Medicago truncatula provided additional evidence that ENOD93 is essential for somatic embryogenesis. This study supports the suitability of EgENOD93 as a marker to predict the potential of leaf explants to produce embryogenic callus. Crosstalk among stresses, auxin, and Nod-factor like signalling molecules likely induces the expression of EgENOD93 for embryogenic callus formation.
PMID: 32734510
Mol Plant Microbe Interact , IF:3.696 , 2020 Nov doi: 10.1094/MPMI-08-20-0233-R
A network of phosphate starvation and immune-related signaling and metabolic pathways controls the interaction between Arabidopsis thaliana and the beneficial fungus Colletotrichum tofieldiae.
Max Planck Institute for Plant Breeding Research, 28303, Plant Microbe Interactions, Carl-von-Linne-Weg 10, Koln, Nordrhein-Westfalen, Germany, 50829; henning_frerigmann@web.de.; Ruhr-Universitat Bochum, 9142, Lehrstuhl fur Molekulargenetik und Physiologie der Pflanzen, Bochum, Nordrhein-Westfalen, Germany; Markus.Piotrowski@ruhr-uni-bochum.de.; Ruhr-Universitat Bochum, 9142, Lehrstuhl fur Molekulargenetik und Physiologie der Pflanzen, Bochum, Nordrhein-Westfalen, Germany; Rene.Lemke@ruhr-uni-bochum.de.; Institute of the Bioorganic Chemistry PAS, 91868, Noskowskiego 12/114, Poznan, Poland, 61-704; bednarek@ibch.poznan.pl.; Max-Planck-Institut fur Pflanzenzuchtungsforschung, 28303, Koln, Nordrhein-Westfalen, Germany; schlef@mpipz.mpg.de.
The beneficial root-colonizing fungus Colletotrichum tofieldiae (Ct) mediates plant growth promotion (PGP) upon phosphate (Pi) starvation in Arabidopsis thaliana (Arabidopsis). This activity is dependent on the Trp-metabolism of the host, including indole glucosinolate (IG) hydrolysis. Here we show that Ct resolves several Pi starvation-induced molecular processes in the host, one of which is the downregulation of auxin signaling in germ-free plants, which is restored in the presence of the fungus. Using CRISPR/Cas9 genome editing, we generated an Arabidopsis triple mutant lacking three homologous nitrilases (NIT1-3) that are thought to link IG-hydrolysis products with auxin biosynthesis. Retained Ct-induced PGP in nit1;2;3 mutant plants demonstrated that this metabolic connection is dispensable for the beneficial activity of the fungus. This suggests that either there is an alternative metabolic link between IG-hydrolysis products and auxin biosynthesis, or that Ct restores auxin signaling independently of IG metabolism. We show that Ct, similar to pathogenic microorganisms, triggers Arabidopsis immune pathways that rely on IG metabolism as well as salicylic acid and ethylene signaling. Analysis of IG-deficient myb mutants revealed that these metabolites are indeed important for control of in planta Ct growth: however, enhanced Ct biomass does not necessarily negatively correlate with PGP. We show that Pi deficiency enables more efficient colonization of Arabidopsis by Ct, possibly due to the MYC2-mediated repression of ethylene signaling and changes in the constitutive IG composition in roots.
PMID: 33226310
BMC Genomics , IF:3.594 , 2020 Nov , V21 (1) : P807 doi: 10.1186/s12864-020-07221-6
Identification of high-copy number long terminal repeat retrotransposons and their expansion in Phalaenopsis orchids.
Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan.; Orchid Research and Development Center, National Cheng Kung University, Tainan, Taiwan.; Institute of Tropical Plant Sciences and Microbiology, National Cheng Kung University, Tainan, Taiwan.; Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China.; Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, Taiwan.; Institute of Plant Genome and Development, University of Perpignan, Perpignan, France.; Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan. hhchen@mail.ncku.edu.tw.; Orchid Research and Development Center, National Cheng Kung University, Tainan, Taiwan. hhchen@mail.ncku.edu.tw.
BACKGROUND: Transposable elements (TEs) are fragments of DNA that can insert into new chromosomal locations. They represent a great proportion of eukaryotic genomes. The identification and characterization of TEs facilitates understanding the transpositional activity of TEs with their effects on the orchid genome structure. RESULTS: We combined the draft whole-genome sequences of Phalaenopsis equestris with BAC end sequences, Roche 454, and Illumina/Solexa, and identified long terminal repeat (LTR) retrotransposons in these genome sequences by using LTRfinder and classified by using Gepard software. Among the 10 families Gypsy-like retrotransposons, three families Gypsy1, Gypsy2, and Gypsy3, contained the most copies among these predicted elements. In addition, six high-copy retrotransposons were identified according to their reads in the sequenced raw data. The 12-kb Orchid-rt1 contains 18,000 copies representing 220 Mbp of the P. equestris genome. Southern blot and slot blot assays showed that these four retrotransposons Gypsy1, Gypsy2, Gypsy3, and Orchid-rt1 contained high copies in the large-genome-size/large-chromosome species P. violacea and P. bellina. Both Orchid-rt1 and Gypsy1 displayed various ratios of copy number for the LTR sequences versus coding sequences among four Phalaenopsis species, including P. violacea and P. bellina and small-genome-size/small-chromosome P. equestris and P. ahprodite subsp. formosana, which suggests that Orchid-rt1 and Gypsy1 have been through various mutations and homologous recombination events. FISH results showed amplification of Orchid-rt1 in the euchromatin regions among the four Phalaenopsis species. The expression levels of Peq018599 encoding copper transporter 1 is highly upregulated with the insertion of Orchid-rt1, while it is down regulated for Peq009948 and Peq014239 encoding for a 26S proteasome non-ATP regulatory subunit 4 homolog and auxin-responsive factor AUX/IAA-related. In addition, insertion of Orchid-rt1 in these three genes are all in their intron regions. CONCLUSION: Orchid-rt1 and Gypsy1-3 have amplified within Phalaenopsis orchids concomitant with the expanded genome sizes, and Orchid-rt1 and Gypsy1 may have gone through various mutations and homologous recombination events. Insertion of Orchid-rt1 is in the introns and affects gene expression levels.
PMID: 33213366
BMC Genomics , IF:3.594 , 2020 Nov , V21 (1) : P803 doi: 10.1186/s12864-020-07214-5
Transcriptome analysis identifies genes involved in the somatic embryogenesis of Eucalyptus.
Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Guangxi Forestry Research Institute, 23 Yongwu Road, Nanning, 530002, Guangxi, China.; Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Guangxi Forestry Research Institute, 23 Yongwu Road, Nanning, 530002, Guangxi, China. bwchen_gfri@163.com.
BACKGROUND: Eucalyptus, a highly diverse genus of the Myrtaceae family, is the most widely planted hardwood in the world due to its increasing importance for fiber and energy. Somatic embryogenesis (SE) is one large-scale method to provide commercial use of the vegetative propagation of Eucalyptus and dedifferentiation is a key step for plant cells to become meristematic. However, little is known about the molecular changes during the Eucalyptus SE. RESULTS: We compared the transcriptome profiles of the differentiated and dedifferentiated tissues of two Eucalyptus species - E. camaldulensis (high embryogenetic potential) and E. grandis x urophylla (low embryogenetic potential). Initially, we identified 18,777 to 20,240 genes in all samples. Compared to the differentiated tissues, we identified 9229 and 8989 differentially expressed genes (DEGs) in the dedifferentiated tissues of E. camaldulensis and E. grandis x urophylla, respectively, and 2687 up-regulated and 2581 down-regulated genes shared. Next, we identified 2003 up-regulated and 1958 down-regulated genes only in E. camaldulensis, including 6 somatic embryogenesis receptor kinase, 17 ethylene, 12 auxin, 83 ribosomal protein, 28 zinc finger protein, 10 heat shock protein, 9 histone, 122 cell wall related and 98 transcription factor genes. Genes from other families like ABA, arabinogalactan protein and late embryogenesis abundant protein were also found to be specifically dysregulated in the dedifferentiation process of E. camaldulensis. Further, we identified 48,447 variants (SNPs and small indels) specific to E. camaldulensis, including 13,434 exonic variants from 4723 genes (e.g., annexin, GN, ARF and AP2-like ethylene-responsive transcription factor). qRT-PCR was used to confirm the gene expression patterns in both E. camaldulensis and E. grandis x urophylla. CONCLUSIONS: This is the first time to study the somatic embryogenesis of Eucalyptus using transcriptome sequencing. It will improve our understanding of the molecular mechanisms of somatic embryogenesis and dedifferentiation in Eucalyptus. Our results provide a valuable resource for future studies in the field of Eucalyptus and will benefit the Eucalyptus breeding program.
PMID: 33208105
BMC Genomics , IF:3.594 , 2020 Nov , V21 (1) : P788 doi: 10.1186/s12864-020-07203-8
The piperazine compound ASP activates an auxin response in Arabidopsis thaliana.
College of Life Sciences, Capital Normal University, Beijing, 100048, China.; College of Life Sciences, Capital Normal University, Beijing, 100048, China. zhaox0521@126.com.
BACKGROUND: Auxins play key roles in the phytohormone network. Early auxin response genes in the AUX/IAA, SAUR, and GH3 families show functional redundancy, which makes it very difficult to study the functions of individual genes based on gene knockout analysis or transgenic technology. As an alternative, chemical genetics provides a powerful approach that can be used to address questions relating to plant hormones. RESULTS: By screening a small-molecule chemical library of compounds that can induce abnormal seedling and vein development, we identified and characterized a piperazine compound 1-[(4-bromophenoxy) acetyl]-4-[(4-fluorophenyl) sulfonyl] piperazine (ASP). The Arabidopsis DR5::GFP line was used to assess if the effects mentioned were correlated with the auxin response, and we accordingly verified that ASP altered the auxin-related pathway. Subsequently, we examined the regulatory roles of ASP in hypocotyl and root development, auxin distribution, and changes in gene expression. Following ASP treatment, we detected hypocotyl elongation concomitant with enhanced cell elongation. Furthermore, seedlings showed retarded primary root growth, reduced gravitropism and increased root hair development. These phenotypes were associated with an increased induction of DR5::GUS expression in the root/stem transition zone and root tips. Auxin-related mutants including tir1-1, aux1-7 and axr2-1 showed phenotypes with different root-development pattern from that of the wild type (Col-0), and were insensitive to ASP. Confocal images of propidium iodide (PI)-stained root tip cells showed no detectable damage by ASP. Furthermore, RT-qPCR analyses of two other genes, namely, Ethylene Response Factor (ERF115) and Mediator 18 (MED18), which are related to cell regeneration and damage, indicated that the ASP inhibitory effect on root growth was not attributable to toxicity. RT-qPCR analysis provided further evidence that ASP induced the expression of early auxin-response-related genes. CONCLUSIONS: ASP altered the auxin response pathway and regulated Arabidopsis growth and development. These results provide a basis for dissecting specific molecular components involved in auxin-regulated developmental processes and offer new opportunities to discover novel molecular players involved in the auxin response.
PMID: 33176686
Plant Sci , IF:3.591 , 2020 Nov , V300 : P110631 doi: 10.1016/j.plantsci.2020.110631
Synthetic auxin herbicides: finding the lock and key to weed resistance.
Department of Agricultural Biology, 1177 Campus Delivery, Colorado State University, Fort Collins, CO 80525, USA. Electronic address: olivia.todd@colostate.edu.; Department of Agricultural Biology, 1177 Campus Delivery, Colorado State University, Fort Collins, CO 80525, USA. Electronic address: marcelo.figueiredo@colostate.edu.; Department of Agricultural Biology, 1177 Campus Delivery, Colorado State University, Fort Collins, CO 80525, USA. Electronic address: sarah.morran@colostate.edu.; Department of Agricultural Biology, 1177 Campus Delivery, Colorado State University, Fort Collins, CO 80525, USA. Electronic address: neeta.soni@colostate.edu.; School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA, 5005, Australia. Electronic address: christopher.preston@adelaide.edu.au.; School of Life Sciences, The University of Warwick, Coventry, CV4 7AL, UK. Electronic address: martin.kubes@warwick.ac.uk.; School of Life Sciences, The University of Warwick, Coventry, CV4 7AL, UK. Electronic address: richard.napier@warwick.ac.uk.; Department of Agricultural Biology, 1177 Campus Delivery, Colorado State University, Fort Collins, CO 80525, USA. Electronic address: todd.gaines@colostate.edu.
Synthetic auxin herbicides are designed to mimic indole-3-acetic acid (IAA), an integral plant hormone affecting cell growth, development, and tropism. In this review, we explore target site genes in the auxin signaling pathway including SCF(TIR1/AFB), Aux/IAA, and ARFs that are confirmed or proposed mechanisms for weed resistance to synthetic auxin herbicides. Resistance to auxin herbicides by metabolism, either by enhanced cytochrome P450 detoxification or by loss of pro-herbicide activation, is a major non-target-site resistance pathway. We speculate about potential fitness costs of resistance due to effects of resistance-conferring mutations, provide insight into the role of polyploidy in synthetic auxin resistance evolution, and address the genetic resources available for weeds. This knowledge will be the key to unlock the long-standing questions as to which components of the auxin signaling pathway are most likely to have a role in resistance evolution. We propose that an ambitious research effort into synthetic auxin herbicide/target site interactions is needed to 1) explain why some synthetic auxin chemical families have activity on certain dicot plant families but not others and 2) fully elucidate target-site cross-resistance patterns among synthetic auxin chemical families to guide best practices for resistance management.
PMID: 33180710
Plant Sci , IF:3.591 , 2020 Nov , V300 : P110624 doi: 10.1016/j.plantsci.2020.110624
TaMYB86B encodes a R2R3-type MYB transcription factor and enhances salt tolerance in wheat.
Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, Shandong, 250014, China.; State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong, 271018, China.; Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, Shandong, 250014, China. Electronic address: suina@sdnu.edu.cn.
The MYB transcription factor family is important for plant responses to abiotic stresses. In this study, we identified three wheat TaMYB86 genes encoding R2R3-type MYB transcription factors. Analyses of the phylogenetic relationships and gene structures of TaMYB86A, TaMYB86B, and TaMYB86D revealed considerable similarities in gene structures and the encoded amino acid sequences. Additionally, TaMYB86B was highly expressed in the roots, stems, and leaves, suggesting it is critical for regulating salt stress responses in wheat. Moreover, TaMYB86B expression was induced by NaCl, abscisic acid (ABA), methyl jasmonate (MeJA), gibberellin (GA), auxin and low temperature treatments. The TaMYB86B protein localized in the nucleus and exhibited transcriptional activation activity. Under salt stress, TaMYB86B-overexpressing plants had a higher biomass and potassium ion (K(+)) content, but lower MDA, H2O2, O2(-.), and sodium ion (Na(+)) contents, when compared with the wild-type plants. Quantitative real-time PCR results indicated that the overexpression of TaMYB86B improved the expression of many stress-related genes. These findings suggest that TaMYB86B influences the salt tolerance of wheat by regulating the ion homeostasis to maintain an appropriate osmotic balance and decrease ROS levels.
PMID: 33180704
Appl Microbiol Biotechnol , IF:3.53 , 2020 Nov , V104 (22) : P9535-9550 doi: 10.1007/s00253-020-10938-9
Bacterial catabolism of indole-3-acetic acid.
Department of Plant Pathology, University of California Davis, Davis, CA, 95616, USA.; Department of Plant Pathology, University of California Davis, Davis, CA, 95616, USA. jleveau@ucdavis.edu.
Indole-3-acetic acid (IAA) is a molecule with the chemical formula C10H9NO2, with a demonstrated presence in various environments and organisms, and with a biological function in several of these organisms, most notably in plants where it acts as a growth hormone. The existence of microorganisms with the ability to catabolize or assimilate IAA has long been recognized. To date, two sets of gene clusters underlying this property in bacteria have been identified and characterized: one (iac) is responsible for the aerobic degradation of IAA into catechol, and another (iaa) for the anaerobic conversion of IAA to 2-aminobenzoyl-CoA. Here, we summarize the literature on the products, reactions, and pathways that these gene clusters encode. We explore two hypotheses about the benefit that iac/iaa gene clusters confer upon their bacterial hosts: (1) exploitation of IAA as a source of carbon, nitrogen, and energy; and (2) interference with IAA-dependent processes and functions in other organisms, including plants. The evidence for both hypotheses will be reviewed for iac/iaa-carrying model strains of Pseudomonas putida, Enterobacter soli, Acinetobacter baumannii, Paraburkholderia phytofirmans, Caballeronia glathei, Aromatoleum evansii, and Aromatoleum aromaticum, more specifically in the context of access to IAA in the environments from which these bacteria were originally isolated, which include not only plants, but also soils and sediment, as well as patients in hospital environments. We end the mini-review with an outlook for iac/iaa-inspired research that addresses current gaps in knowledge, biotechnological applications of iac/iaa-encoded enzymology, and the use of IAA-destroying bacteria to treat pathologies related to IAA excess in plants and humans. KEY POINTS: * The iac/iaa gene clusters encode bacterial catabolism of the plant growth hormone IAA. * Plants are not the only environment where IAA or IAA-degrading bacteria can be found. * The iac/iaa genes allow growth at the expense of IAA; other benefits remain unknown.
PMID: 33037916
J Biotechnol , IF:3.503 , 2020 Nov doi: 10.1016/j.jbiotec.2020.10.029
Azospirillum brasilense reduces oxidative stress in the green microalgae Chlorella sorokiniana under different stressors.
Biosystems Engineering, Auburn University, Auburn, AL 36849, USA.; Bashan Institute of Science, Dadeville, AL 36853, USA; Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), Av. IPN 195, 23096, La Paz, BCS, Mexico; Dept. of Entomology and Plant Pathology, 301 Funchess Hall, Auburn University, Auburn, AL 36849, USA.; Biosystems Engineering, Auburn University, Auburn, AL 36849, USA. Electronic address: bth0023@auburn.edu.
In this study, we investigated oxidative stress in the green microalgae, Chlorella sorokiniana, in co-culture with the plant growth promoting bacteria (PGPB), Azospirillum brasilense. This relationship was studied in the absence of an exogenous stressor, under copper stress, and under nitrogen limitation stress. We confirmed that copper and nitrogen limitation induced algal oxidative stress and reductions in chlorophyll content. In all cases, the presence of A. brasilense lowered the accumulation of intracellular reactive oxygen species (ROS) while promoting chlorophyll content. This effect was driven, in part, by A. brasilense's secretion of the auxin hormone, indole-3-acetic acid, which is known to mitigate stress in higher plants. The findings of the present study show that stress mitigation by A. brasilense resulted in suppressed starch accumulation under nitrogen limitation stress and neutral lipid accumulation under copper stress. In fact, A. brasilense could almost completely mitigate oxidative stress in C. sorokiniana resulting from nitrogen limitation, with ROS accumulation rates comparable to the axenic control cultures. The biotechnological implication of these findings is that co-culture strategies with A. brasilense (and similar PGPB) are most effective for high growth applications. A second growth stage may be needed to induce accumulation of desired products.
PMID: 33147514
BMC Plant Biol , IF:3.497 , 2020 Nov , V20 (1) : P536 doi: 10.1186/s12870-020-02747-z
Melatonin promotes adventitious root formation in apple by promoting the function of MdWOX11.
College of Horticulture, Northwest Agriculture & Forestry University, Yangling, 712100, China.; College of Life Science, Northwest Agriculture & Forestry University, Yangling, 712100, China.; College of Horticulture, Northwest Agriculture & Forestry University, Yangling, 712100, China. afant@nwsuaf.edu.cn.; College of Life Science, Northwest Agriculture & Forestry University, Yangling, 712100, China. afant@nwsuaf.edu.cn.
BACKGROUND: Melatonin (MT) is important for plant growth and development; however, it is not known whether MT is involved in apple adventitious root (AR) development. In this study, we treated Malus prunifolia (MP) at four different stages of AR development, and analyzed the level of the endogenous hormones MT, auxin (IAA), zeatin-riboside (ZR), abscisic acid (ABA), and gibberellins (GA1 + 3) in all four treatment groups and the untreated control group. The expression of MT, IAA biosynthesis, transport and signal transduction, the cell cycle, and root development related genes were quantified by RT-qPCR. The function of MdWOX11 was analyzed in transgenic apple plants. RESULTS: The promotion of AR development by MT was dependent on the stage of AR induction between 0 and 2 d in apple rootstocks. MT-treatment increased the level of IAA and crosstalk existed between MT and IAA during AR formation. The expression of MdWOX11 was induced by MT treatment and positively regulated AR formation in apple. Furthermore, transgenic lines that overexpressed MdWOX11 lines produced more ARs than 'GL3'. Phenotypic analysis indicated that MdWOX11 overexpression lines were more sensitive to exogenous MT treatment than 'GL3', suggesting that MdWOX11 regulates AR formation in response to MT in apple rootstock. CONCLUSIONS: MT promotes AR formation mainly during the AR induction stage by inducing IAA levels and upregulating MdWOX11.
PMID: 33243138
Plant Mol Biol , IF:3.302 , 2020 Nov , V104 (4-5) : P529-548 doi: 10.1007/s11103-020-01058-z
Transcriptome sequencing and metabolite profiling analyses provide comprehensive insight into molecular mechanisms of flower development in Dendrobium officinale (Orchidaceae).
Key Laboratory of South China Agricultural Plant Molecular Analysis and Gene Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.; , Kagawa-ken, Japan.; Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.; University of the Chinese Academy of Sciences, Beijing, 100049, China.; Key Laboratory of South China Agricultural Plant Molecular Analysis and Gene Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China. duanj@scib.ac.cn.; Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, 510650, China. duanj@scib.ac.cn.
KEY MESSAGE: This research provides comprehensive insight into the molecular networks and molecular mechanisms underlying D. officinale flower development. Flowers are complex reproductive organs and play a crucial role in plant propagation, while also providing sustenance for insects and natural bioactive metabolites for humans. However, knowledge about gene regulation and floral metabolomes in flowers is limited. In this study, we used an important orchid species (Dendrobium officinale), whose flowers can be used to make herbal tea, to perform transcriptome sequencing and metabolic profiling of early- and medium-stage flower buds, as well as opened flowers, to provide comprehensive insight into the molecular mechanisms underlying flower development. A total of 8019 differentially expressed genes (DEGs) and 239 differentiated metabolites were found. The transcription factors that were identified and analyzed belong exclusively to the MIKC-type MADS-box proteins and auxin responsive factors that are known to be involved in flower development. The expression of genes involved in chlorophyll and carotenoid biosynthesis strongly matched the metabolite accumulation patterns. The genes related to flavonoid and polysaccharide biosynthesis were active during flower development. Interestingly, indole-3-acetic acid and abscisic acid, whose trend of accumulation was inverse during flower development, may play an important role in this process. Collectively, the identification of DEGs and differentiated metabolites could help to illustrate the regulatory networks and molecular mechanisms important for flower development in this orchid.
PMID: 32876816
Mycorrhiza , IF:3.069 , 2020 Nov doi: 10.1007/s00572-020-01005-2
Phytohormones and volatile organic compounds, like geosmin, in the ectomycorrhiza of Tricholoma vaccinum and Norway spruce (Picea abies).
Institute of Microbiology, Microbial Communication, Friedrich Schiller University Jena, Neugasse 25, 07743, Jena, Germany.; Max Planck Institute for Chemical Ecology, Hans-Knoll-Strasse 8, 07745, Jena, Germany.; Institute of Microbiology, Microbial Communication, Friedrich Schiller University Jena, Neugasse 25, 07743, Jena, Germany. katrin.krause@uni-jena.de.
The ectomycorrhizospheric habitat contains a diverse pool of organisms, including the host plant, mycorrhizal fungi, and other rhizospheric microorganisms. Different signaling molecules may influence the ectomycorrhizal symbiosis. Here, we investigated the potential of the basidiomycete Tricholoma vaccinum to produce communication molecules for the interaction with its coniferous host, Norway spruce (Picea abies). We focused on the production of volatile organic compounds and phytohormones in axenic T. vaccinum cultures, identified the potential biosynthesis genes, and investigated their expression by RNA-Seq analyses. T. vaccinum released volatiles not usually associated with fungi, like limonene and beta-barbatene, and geosmin. Using stable isotope labeling, the biosynthesis of geosmin was elucidated. The geosmin biosynthesis gene ges1 of T. vaccinum was identified, and up-regulation was scored during mycorrhiza, while a different regulation was seen with mycorrhizosphere bacteria. The fungus also released the volatile phytohormone ethylene and excreted salicylic and abscisic acid as well as jasmonates into the medium. The tree excreted the auxin, indole-3-acetic acid, and its biosynthesis intermediate, indole-3-acetamide, as well as salicylic acid with its root exudates. These compounds could be shown for the first time in exudates as well as in soil of a natural ectomycorrhizospheric habitat. The effects of phytohormones present in the mycorrhizosphere on hyphal branching of T. vaccinum were assessed. Salicylic and abscisic acid changed hyphal branching in a concentration-dependent manner. Since extensive branching is important for mycorrhiza establishment, a well-balanced level of mycorrhizospheric phytohormones is necessary. The regulation thus can be expected to contribute to an interkingdom language.
PMID: 33210234
Environ Sci Pollut Res Int , IF:3.056 , 2020 Nov , V27 (31) : P38501-38512 doi: 10.1007/s11356-020-10370-6
Herbicides based on 2,4-D: its behavior in agricultural environments and microbial biodegradation aspects. A review.
Instituto de Investigacion en Micologia y Micotoxicologia (IMICO-CONICET). Departamento de Microbiologia e Inmunologia, Facultad de Ciencias Exactas, Fisico, Quimicas y Naturales, Universidad Nacional de Rio Cuarto, Ruta Nacional N degrees 36 Km 601, 5800, Rio Cuarto, Cordoba, Argentina.; Instituto de Investigacion en Micologia y Micotoxicologia (IMICO-CONICET). Departamento de Microbiologia e Inmunologia, Facultad de Ciencias Exactas, Fisico, Quimicas y Naturales, Universidad Nacional de Rio Cuarto, Ruta Nacional N degrees 36 Km 601, 5800, Rio Cuarto, Cordoba, Argentina. cbarberis@exa.unrc.edu.ar.
One of the main herbicides used in the agricultural environments is 2,4-dichlorophenoxyacetic acid (2,4-D). It is a synthetic plant hormone auxin employed in many crops including rice, wheat, sorghum, sugar cane, and corn to control wide leaf weeds. The indiscriminate use of pesticides can produce numerous damages to the environment. Therefore, this review has the objective to provide an overview on the main characteristics of the herbicides based on 2,4-D, mostly on the role of microorganisms in its degradation and its main degradation metabolite, 2,4- dichlorophenol (2,4-DCP). The remediation processes carried out by microorganisms are advantageous to avoid the pollution of the environment as well as to safeguard the population health.
PMID: 32770339
Phytochemistry , IF:3.044 , 2020 Nov , V181 : P112582 doi: 10.1016/j.phytochem.2020.112582
Comparative transcriptome analysis reveals the regulatory effects of acetylcholine on salt tolerance of Nicotiana benthamiana.
College of Life Sciences, Northwest Agriculture & Forestry University, 712100, Yangling, China.; Cangzhou Central Hospital, 061000 Cangzhou, China.; Shaanxi Tobacco Scientific Institution, 71000, Xi'an, China.; Department of Pomology, National Research Centre, 12622 Cairo, Egypt.; University of Agriculture, Faisalabad, 38000 Faisalabad, Pakistan.; College of Life Sciences, Northwest Agriculture & Forestry University, 712100, Yangling, China. Electronic address: zhanglixin@nwafu.edu.cn.
Salinity is a major cause of crop losses worldwide. Acetylcholine (ACh) can ameliorate the adverse effects of abiotic stresses on plant growth, including salinity stress; however, the underlying molecular mechanisms of this process are unclear. Here, seedlings of Nicotiana benthamiana grown under normal conditions or exposed to 150 mmol L(-1) NaCl salinity stress were then treated with a root application of 10 muM ACh. Exogenous ACh application resulted in the downregulation of the activity of the antioxidant enzymes, ascorbate peroxidase, and catalase. ACh-treated plants had lower levels of reactive oxygen species, including the superoxide anion radical and hydrogen peroxide. Transcriptome analysis indicated that ACh treatment under salt stress promoted the differential expression of 658 genes in leaves of N. benthamiana (527 were upregulated and 131 were downregulated). Gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses revealed that exogenous ACh application was associated with a substantial increase in the transcripts of genes related to cell wall peroxidases, xyloglucan endotransglucosylases or hydrolases, and expansins, indicating that ACh activates cell wall biosynthesis in salt-stressed plants. ACh also enhanced the expression of genes associated with the auxin, gibberellin, brassinosteroid, and salicylic acid signalling pathways, indicating that ACh induces the activation of these pathways under salt stress. Collectively, these findings indicate that ACh-induced salt tolerance in N. benthamiana seedlings is mediated by the inhibition of antioxidant enzymes, activation of cell wall biosynthesis, and hormone signalling pathways. Stress-induced genes involved in osmotic regulation and oxidation resistance were induced by ACh under salt stress. The genes whose transcript levels were elevated by ACh treatment in salt-stressed N. benthamiana could be used as molecular markers of the physiological status of plants under salt stress.
PMID: 33246307
Am J Bot , IF:3.038 , 2020 Nov doi: 10.1002/ajb2.1570
Leaf dorsoventrality candidate gene CpARF4 has conserved expression pattern but divergent tasiR-ARF regulation in the water fern Ceratopteris pteridoides.
Laboratory of Plant Resource Conservation and Utilization, Jishou University, Jishou, 416000, China.
PREMISE: Leaves are traditionally classified into microphylls and megaphylls, and recently have been regarded as independently originating in lycophytes, ferns, and seed plants. The developmental genetics of leaf dorsoventrality, a synapomorphy in vascular plants, has been extensively studied in flowering plants. AUXIN RESPONSE FACTOR4 (ARF4) genes are key to leaf abaxial identity in flowering plants, but whether they exist in ferns is still an open question. METHODS: ARF4 genes from Ceratopteris pteridoides, Cyrtomium guizhouense, and Parathelypteris nipponica were mined from transcriptomes and investigated in terms of evolutionary phylogeny and sequence motifs, with a focus on the tasiR-ARF binding site. In situ hybridization was used to localize expression of CpARF4 in Ceratopteris pteridoides. 5'RNA ligase-mediated-RACE was employed to verify whether CpARF4 transcripts were sliced by tasiR-ARF. RESULTS: ARF4 genes exist in ferns, and this lineage originates from a gene duplication in the common ancestor of ferns and seed plants. ARF4 genes are of a single copy in the ferns studied here, and they contain divergent and, at most, one tasiR-ARF binding site. CpARF4 is expressed in the abaxial but not the adaxial domain of leaf primordia at various developmental stages. Transcript slicing guided by tasiR-ARF is active in C. pteridoides, but CpARF4 probably has not been affected by it. CONCLUSIONS: Fern ARF4 genes differ in copy number and tasiR-ARF regulation relative to flowering plants, though they can be similarly expressed in the abaxial domain of leaves, revealing a key role for ARF4 genes in the evolution of leaf dorsoventrality of vascular plants.
PMID: 33216953
J Plant Physiol , IF:3.013 , 2020 Nov , V256 : P153312 doi: 10.1016/j.jplph.2020.153312
Pea GH3 acyl acid amidosynthetase conjugates IAA to proteins in immature seeds of Pisum sativum L. - A new perspective on formation of high-molecular weight conjugates of auxin.
Department of Biochemistry, Nicolaus Copernicus University, Lwowska 1, 87-100, Torun, Poland. Electronic address: maciejost@umk.pl.; Department of Biochemistry, Nicolaus Copernicus University, Lwowska 1, 87-100, Torun, Poland. Electronic address: annaciar@doktorant.umk.pl.
Gretchen Hagen 3 (GH3) acyl acid amidosynthetases are encoded by early auxin-responsive genes and catalyze an ATP-dependent biosynthesis of IAA-amino acid conjugates. An amide conjugate of IAA, indole-3-acetyl-aspartate (IAA-aspartate, IAA-Asp), is a predominant form of bound auxin in immature seeds of pea. However, there is some evidence that IAA is also able to form high molecular weight amide conjugates with proteins in pea and other plant species. In this short study we report that recombinant PsGH3 IAA-amino acid synthetase, which exhibits a preference for the formation of IAA-Asp, can also conjugate IAA with the protein fraction from immature seeds of pea (S-10 fraction). We studied [(14)C]IAA incorporation to the S-10 protein fraction by two assays: TLC method and protein precipitation by trichloroacetic acid (TCA). In both cases, radioactivity of [(14)C]IAA in the protein fraction increases in comparison to the control (without PsGH3), about 9.3- and 3.17-fold, respectively. l-Asp, as a preferred substrate in the IAA conjugation catalyzed by PsGH3, down-regulates [(14)C]IAA conjugation to the proteins as shown by the TLC assay ( approximately 2.8-fold decrease) and the TCA precipitation variant ( approximately 2-fold decrease). Moreover, l-Trp that competes with Asp for the catalytic site of PsGH3 and inhibits activity of the enzyme, diminished radioactivity of [(14)C]IAA-proteins about 1.2- and 2.8-fold, respectively. Taking into account that amino group of an amino acid or a protein acts as an acceptor of the indole-3-acetyl moiety from IAA-AMP intermediate during GH3-dependent conjugation, we masked amine groups (alpha- and epsilon-NH2) of the S-10 protein fraction from pea seeds by reductive alkylation. The alkylated proteins revealed about 3- and 2.8-fold lower radioactivity of [(14)C]IAA than non-alkylated fraction for TLC and TCA precipitation variant, respectively. This is a first study demonstrating that formation of high molecular weight IAA conjugates with proteins is catalyzed by a GH3 acyl acid amidosynthetase.
PMID: 33161181
J Plant Physiol , IF:3.013 , 2020 Nov , V256 : P153310 doi: 10.1016/j.jplph.2020.153310
Transcriptomic analysis reveals the contribution of auxin on the differentially developed caryopses on primary and secondary branches in rice.
Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China. Electronic address: jiashenghua_37@163.com.; Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China. Electronic address: 670310185@qq.com.; Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China. Electronic address: 1598770260@qq.com.; Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China. Electronic address: zhiriyulin@sina.com.; Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China. Electronic address: xichao@bnu.edu.cn.; Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China. Electronic address: liujin@bnu.edu.cn.; Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China. Electronic address: hpzhao@bnu.edu.cn.; Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China; Academy of Plateau Science and Sustainability of the People's Government of Qinghai Province & Beijing Normal University, Qinghai Normal University, Xining, 810008, Qinghai, China. Electronic address: schan@bnu.edu.cn.; Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China; Academy of Plateau Science and Sustainability of the People's Government of Qinghai Province & Beijing Normal University, Qinghai Normal University, Xining, 810008, Qinghai, China. Electronic address: ydwang@bnu.edu.cn.
Generally, the caryopses located on proximal secondary branches (CSB) have smaller grain size and slower and poorer filling rate than those on apical primary branches (CPB) in rice, which greatly limits the grain yield potential fulfillment. However, the key regulators determining the developmental differences between CPB and CSB remain elusive. Here, we have performed transcriptomic analysis in CPB and CSB at four developmental stages [0, 5, 12 and 20 days after fertilization (DAF)] using high-throughput RNA-sequencing technique. Based on gene expression cluster analysis, the genes expressed in CPB and CSB were clustered into two subtypes in a positional-independent manner: one includes 0- and 5-DAF CPB and CSB, and 12-DAF CSB; another includes 12-DAF CPB, 20-DAF CPB and CSB. Moreover, according to the expression value of each gene, K-mean cluster analysis showed that the K4 to K6 classifiers contain the genes highly expressed in 5-DAF CPB and 12-DAF CSB, which were enriched in DNA synthesis, protein synthesis and cell proliferation mainly responsible for grain size decision. Then, functional enrichment analysis in Gene Ontology database showed that auxin-related genes were relatively enriched, indicating that auxin might be the key determinant for gene expression in K4 to K6 classifiers. Finally, the application of exogenous IAA in CSB before fertilization promoted gene expression, caryopsis development and grain weight closer to that in CPB, providing a molecular framework to optimize CSB development and potential targets for increasing grain yield.
PMID: 33157456
J Plant Physiol , IF:3.013 , 2020 Nov , V254 : P153281 doi: 10.1016/j.jplph.2020.153281
Low nitrogen induces root elongation via auxin-induced acid growth and auxin-regulated target of rapamycin (TOR) pathway in maize.
College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, Key Laboratory of Plant-Soil Interactions, Ministry of Education, China Agricultural University, Beijing, 100193, China; Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin, 300191, China. Electronic address: 915634280@qq.com.; College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, Key Laboratory of Plant-Soil Interactions, Ministry of Education, China Agricultural University, Beijing, 100193, China. Electronic address: 13538807170@163.com.; College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, Key Laboratory of Plant-Soil Interactions, Ministry of Education, China Agricultural University, Beijing, 100193, China. Electronic address: wp.102300@163.com.; College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, Key Laboratory of Plant-Soil Interactions, Ministry of Education, China Agricultural University, Beijing, 100193, China. Electronic address: caucfj@cau.edu.cn.; College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, Key Laboratory of Plant-Soil Interactions, Ministry of Education, China Agricultural University, Beijing, 100193, China. Electronic address: yuanlixing@cau.edu.cn.; College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, Key Laboratory of Plant-Soil Interactions, Ministry of Education, China Agricultural University, Beijing, 100193, China. Electronic address: miguohua@cau.edu.cn.
Under low nitrogen (N) supply, an important adaption of the maize root system is to promote the root elongation so as to increase N uptake from a larger soil space. The underlying physiological mechanism is largely unknown. In the present study, two maize inbred lines (Ye478 and Wu312) were used to study the possible involvement of the auxin and target of rapamycin (TOR) pathway in low-N-induced root elongation. Compared to Wu312, primary root elongation of Ye478 was more sensitive to low nitrate supply. Correspondingly, more auxin was accumulated in the root tip, and more protons were secreted, increasing the acidity of the apoplast space. On the other hand, low-N-induced root elongation was greatly reduced when shoot-to-root auxin transport was inhibited by applying N-1-naphthylphthalamic acid (NPA) at the plant base or by pruning the top leaf where auxin is mostly synthesized. Furthermore, exogenous application of TOR inhibitor also eliminated the response of root elongation under low N. The content of TOR kinase and the expression of TOR pathway-related genes were significantly changed when shoot-to-root auxin transport was reduced by NPA treatment. Taken together, it is concluded that low-N stress increases shoot-to-root auxin transport which enhances root elongation via auxin-dependent acid growth and the auxin-regulated TOR pathway in maize.
PMID: 32971423
Biochem Biophys Res Commun , IF:2.985 , 2020 Nov doi: 10.1016/j.bbrc.2020.10.088
Phytochrome-interacting factor 4 (PIF4) inhibits expression of SHORT HYPOCOTYL 2 (SHY2) to promote hypocotyl growth during shade avoidance in Arabidopsis.
School of Life Science and Engineering, Henan University of Urban Construction, Pingdingshan, Henan, 467044, China.; Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang, 621000, China.; Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, China. Electronic address: zhdawei@scu.edu.cn.; Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, China. Electronic address: hhlin@scu.edu.cn.
Plants sense the presence of competing neighboring vegetation as a change in light quality. These changes initiate shade avoidance syndrome (SAS) responses. PHYTOCHROME INTERACTING FACTORS (PIFs) are crucial factors in the SAS response. In particular, they mediate the expression of multiple phytohormones and cell expansion genes. Many positive regulatory factors in the SAS response have been identified, but the negative regulation of SAS transcription factors remains poorly understood. The functions of the short hypocotyl 2 (SHY2) transcription factor during the SAS response have not been established, although its roles in the participating hormone and stress responses are well documented. Here, the SHY2 loss-of-function (shy2-31) mutant had a longer hypocotyl, but the gain-of-function (shy2-2) hypocotyl was shorter than that of the wild type under white and shade conditions. We showed that the SHY2 expression level and its associated protein significantly accumulated under shade conditions. Furthermore, SHY2 transcript levels significantly increased in mutant pifQ, but decreased in PIF4OX compared to the wild type, which indicated that PIF4 is a transcriptional repressor of SHY2. ChIP assays have consistently shown that PIF4 directly binds to the promoters of SHY2. We further show that PIF4OX partially rescued the short hypocotyl characteristic of shy2-2 under white and shade conditions. Our results provide new insights into the regulatory mechanisms controlling SAS mediated elongation of the hypocotyl by PIF4-SHY2 modules in Arabidopsis.
PMID: 33153717
Biochem Biophys Res Commun , IF:2.985 , 2020 Nov , V532 (4) : P633-639 doi: 10.1016/j.bbrc.2020.08.057
Nitrate reductase is a key enzyme responsible for nitrogen-regulated auxin accumulation in Arabidopsis roots.
College of Resources, Sichuan Agricultural University, Chengdu, 611130, China.; College of Resources, Sichuan Agricultural University, Chengdu, 611130, China. Electronic address: roundtree318@hotmail.com.
Nitrate reductase (NR) is one of the key enzymes for plant nitrogen assimilation and root architecture remodeling. However, crosstalk between NR-mediated signaling and auxin-mediated root development in nitrogen-status responses has not been investigated in details before. In this study, root phenotype and auxin distribution in nia1/nia2 (nitrate reductase) double mutant and chl1-5 (nitrate transporter NRT1.1) mutant under different nitrogen availabilities were compared. The nia1/nia2 mutant showed very low expression levels of auxin biosynthetic/signaling genes and was insensitive to nitrogen changes. While the chl1-5 mutant showed a high NR activity with a high level of auxin in the meristematic zone and a weaker response to nitrogen changes, when compared with the wild-type plants. We firstly found that NR activity was roughly positive-correlated with the root auxin level, and there is a crosstalk between nitrate signaling and auxin signaling. The putative signaling pathways downstream of NR have been discussed.
PMID: 32907713
Biochem Biophys Res Commun , IF:2.985 , 2020 Nov , V532 (2) : P244-250 doi: 10.1016/j.bbrc.2020.08.026
UDP-glucosyltransferase UGT84B1 regulates the levels of indole-3-acetic acid and phenylacetic acid in Arabidopsis.
Department of Biological Production Science, United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan.; Department of Bioregulation and Biointeraction, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan.; Department of Applied Biological Science, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan.; Section of Cell and Developmental Biology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0116, USA.; Department of Biochemistry, Okayama University of Science, Okayama, 700-0005, Japan.; Laboratory of Biochemistry, Wageningen University & Research, 6708 WE Wageningen, the Netherlands.; Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan; RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan. Electronic address: kasahara@go.tuat.ac.jp.
Auxin is a key plant growth regulator for diverse developmental processes in plants. Indole-3-acetic acid (IAA) is a primary plant auxin that regulates the formation of various organs. Plants also produce phenylacetic acid (PAA), another natural auxin, which occurs more abundantly than IAA in various plant species. Although it has been demonstrated that the two auxins have distinct transport characteristics, the metabolic pathways and physiological roles of PAA in plants remain unsolved. In this study, we investigated the role of Arabidopsis UDP-glucosyltransferase UGT84B1 in IAA and PAA metabolism. We demonstrated that UGT84B1, which converts IAA to IAA-glucoside (IAA-Glc), can also catalyze the conversion of PAA to PAA-glucoside (PAA-Glc), with a higher catalytic activity in vitro. Furthermore, we showed a significant increase in both the IAA and PAA levels in the ugt84b1 null mutants. However, no obvious developmental phenotypes were observed in the ugt84b1 mutants under laboratory growth conditions. Moreover, the overexpression of UGT84B1 resulted in auxin-deficient root phenotypes and changes in the IAA and PAA levels. Our results indicate that UGT84B1 plays an important role in IAA and PAA homeostasis in Arabidopsis.
PMID: 32868079
Mol Genet Genomics , IF:2.797 , 2020 Nov , V295 (6) : P1443-1457 doi: 10.1007/s00438-020-01712-7
Technical benefit on apple fruit of controlled atmosphere influenced by 1-MCP at molecular levels.
Departamento de Ciencia e Tecnologia Agroindustrial, Faculdade de Agronomia Eliseu 'Maciel', Universidade Federal de Pelotas, Pelota, RS, 96050-500, Brazil.; EMBRAPA Uva e Vinho, R. Livramento 515, Bento Goncalves, RS, 957000-000, Brazil. isarubin@mail.com.; Batiment B, Institut de Recherche en Horticulture et Semences IRHS, Institut National de La Recherche Agronomique INRA, 49071, Beaucouze, France.; EMBRAPA Uva e Vinho, R. Livramento 515, Bento Goncalves, RS, 957000-000, Brazil.
The apple is a highly perishable fruit after harvesting and, therefore, several storage technologies have been studied to provide the consumer market with a quality product with a longer shelf life. However, little is known about the apple genome that is submitted to the storage, and even less with the application of ripening inhibitors. Due to these factors, this study sought to elucidate the transcriptional profile of apple cultivate Gala stored in a controlled atmosphere (AC) treated and not treated with 1-methyl cyclopropene (1-MCP). Through the genetic mapping of the apple, applying the microarray technique, it was possible to verify the action of treatments on transcripts related to photosynthesis, carbohydrate metabolism, response to hormonal stimuli, nucleic acid metabolism, reduction of oxidation, regulation of transcription and metabolism of cell wall and lipids. The results showed that the transcriptional profile in the entire genome of the fruit showed significant differences in the relative expression of the gene, this in response to CA in the presence and absence of 1-MCP. It should be noted that the transcription genes involved in the anabolic pathway were only maintained after six months in fruits treated with 1-MCP. The data in this work suggests that the apple in the absence of 1-MCP begins to prepare its metabolism to mature, even during the storage period in AC. Meanwhile, in the presence of the inhibitor, the transcriptional profile of the fruit is similar to that at the time of harvest. It was also found that a set of genes that code for ethylene receptors, auxin homeostasis, MADS Box, and NAC transcription factors may be involved in the regulation of post-harvest ripening after storage and in the absence of 1-MCP.
PMID: 32700103
Plants (Basel) , IF:2.762 , 2020 Nov , V9 (11) doi: 10.3390/plants9111543
Recent Advances in Adventitious Root Formation in Chestnut.
Department of Plant Physiology, Instituto de Investigaciones Agrobiologicas de Galicia, Consejo Superior de Investigaciones Cientificas, 15705 Santiago de Compostela, Spain.
The genus Castanea includes several tree species that are relevant because of their geographical extension and their multipurpose character, that includes nut and timber production. However, commercial exploitation of the trees is hindered by several factors, particularly by their limited regeneration ability. Regardless of recent advances, there exists a serious limitation for the propagation of elite genotypes of chestnut due to decline of rooting ability as the tree ages. In the present review, we summarize the research developed in this genus during the last three decades concerning the formation of adventitious roots (ARs). Focusing on cuttings and in vitro microshoots, we gather the information available on several species, particularly C. sativa, C. dentata and the hybrid C.sativa x C. crenata, and analyze the influence of several factors on the achievements of the applied protocols, including genotype, auxin treatment, light regime and rooting media. We also pay attention to the acclimation phase, as well as compile the information available about biochemical and molecular related aspects. Furthermore, we considerate promising biotechnological approaches that might enable the improvement of the current protocols.
PMID: 33187282
Plants (Basel) , IF:2.762 , 2020 Nov , V9 (11) doi: 10.3390/plants9111527
ER-Localized PIN Carriers: Regulators of Intracellular Auxin Homeostasis.
Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 16502 Prague, Czech Republic.; Department of Experimental Plant Biology, Faculty of Science, Charles University, 12844 Prague, Czech Republic.
The proper distribution of the hormone auxin is essential for plant development. It is channeled by auxin efflux carriers of the PIN family, typically asymmetrically located on the plasma membrane (PM). Several studies demonstrated that some PIN transporters are also located at the endoplasmic reticulum (ER). From the PM-PINs, they differ in a shorter internal hydrophilic loop, which carries the most important structural features required for their subcellular localization, but their biological role is otherwise relatively poorly known. We discuss how ER-PINs take part in maintaining intracellular auxin homeostasis, possibly by modulating the internal levels of IAA; it seems that the exact identity of the metabolites downstream of ER-PINs is not entirely clear as well. We further review the current knowledge about their predicted structure, evolution and localization. Finally, we also summarize their role in plant development.
PMID: 33182545
Plants (Basel) , IF:2.762 , 2020 Nov , V9 (11) doi: 10.3390/plants9111481
Short De-Etiolation Increases the Rooting of VC801 Avocado Rootstock.
The Institute of Plant Sciences, The Volcani Center, ARO, 68 HaMaccabim Road, Rishon LeZion 7528809, Israel.; The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel.; The Institute of Post Harvest and Food Sciences, The Volcani Center, ARO, 68 HaMaccabim Road, Rishon LeZion 7528809, Israel.
Dark-grown (etiolated) branches of many recalcitrant plant species root better than their green counterparts. Here it was hypothesized that changes in cell-wall properties and hormones occurring during etiolation contribute to rooting efficiency. Measurements of chlorophyll, carbohydrate and auxin contents, as well as tissue compression, histological analysis and gene-expression profiles were determined in etiolated and de-etiolated branches of the avocado rootstock VC801. Differences in chlorophyll content and tissue rigidity, and changes in xyloglucan and pectin in cambium and parenchyma cells were found. Interestingly, lignin and sugar contents were similar, suggesting that de-etiolated branches resemble the etiolated ones in this respect. Surprisingly, the branches that underwent short de-etiolation rooted better than the etiolated ones, and only a slight difference in IAA content between the two was observed. Gene-expression profiles revealed an increase in ethylene-responsive transcripts in the etiolated branches, which correlated with enrichment in xyloglucan hydrolases. In contrast, transcripts encoding pectin methylesterase and pectolyases were enriched in the de-etiolated branches. Taken together, it seems that the short de-etiolation period led to fine tuning of the conditions favoring adventitious root formation in terms of auxin-ethylene balance and cell-wall properties.
PMID: 33153170
Funct Plant Biol , IF:2.617 , 2020 Nov , V47 (12) : P1062-1072 doi: 10.1071/FP20133
Altered localisation of ZmPIN1a proteins in plasma membranes responsible for enhanced-polar auxin transport in etiolated maize seedlings under microgravity conditions in space.
Faculty of Agriculture, Tottori University, 4-101 Koyamacho-minami, Tottori 680-8553, Japan; and Corresponding authors. Email: m.oka@tottori-u.ac.jp; ueda@b.s.osakafu-u.ac.jp.; Future Development Division, Advanced Engineering Services Co., Ltd, 1-6-1 Takezono, Tsukuba, Ibaraki 305-0032, Japan.; Faculty of Agriculture, Tottori University, 4-101 Koyamacho-minami, Tottori 680-8553, Japan.; Faculty of Liberal Arts and Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.; Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.; JEM Mission Operations and Integration Center, Human Spaceflight Technology Directorate, Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505, Japan.; Technology and Research Promotion Department, Japan Space Forum, Shin-Otemachi Bldg., 2-2-1 Otemachi, Chiyoda-ku, Tokyo 100-0004, Japan.; Utilization Engineering Department, Japan Manned Space Systems Corporation, Space Station Test Building, Tsukuba Space Center, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505, Japan.; Kibo Utilization Center, Human Spaceflight Technology Directorate, Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505, Japan.; Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan; and Corresponding authors. Email: m.oka@tottori-u.ac.jp; ueda@b.s.osakafu-u.ac.jp.
In the International Space Station experiment 'Auxin Transport', polar auxin transport (PAT) in shoots of etiolated maize (Zea mays L. cv. Golden Cross Bantam) grown under microgravity in space was substantially enhanced compared with those grown on Earth. To clarify the mechanism, the effects of microgravity on expression of ZmPIN1a encoding essential auxin efflux carrier and cellular localisation of its products were investigated. The amounts of ZmPIN1a mRNA in the coleoptiles and the mesocotyls in space-grown seedlings were almost the same as those in 1 g-grown seedlings, but its products were not. Immunohistochemical analysis with anti-ZmPIN1a antibody revealed a majority of ZmPIN1a localised in the basal side of plasma membranes of endodermal cells in the coleoptiles and the mesocotyls, and in the basal and lateral sides of plasma membranes in coleoptile parenchymatous cells, in which it directed towards the radial direction, but not towards the vascular bundle direction. Microgravity dramatically altered ZmPIN1a localisation in plasma membranes in coleoptile parenchymatous cells, shifting mainly towards the vascular bundle direction. These results suggest that mechanism of microgravity-enhanced PAT in maize shoots is more likely to be due to the enhanced ZmPIN1a accumulation and the altered ZmPIN1a localisation in parenchymatous cells of the coleoptiles.
PMID: 32635987
Funct Plant Biol , IF:2.617 , 2020 Nov , V47 (12) : P1073-1082 doi: 10.1071/FP20093
Transcriptome analysis provides insights into the molecular bases in response to different nitrogen forms-induced oxidative stress in tea plant roots (Camellia sinensis).
State Key Laboratory of Tea Plant Biology and Utilisation, Anhui Agricultural University, Hefei 230036, China; and Corresponding author. Email: zpchen@ahau.edu.cn.; State Key Laboratory of Tea Plant Biology and Utilisation, Anhui Agricultural University, Hefei 230036, China.; School of Biology, Food and Environment, Hefei University, Hefei 230601, China.
Previous studies have suggested that the maintenance of redox homeostasis is essential for plant growth. Here we investigated how redox homeostasis and signalling is modulated in response to different nitrogen (N) forms in tea plant roots. Our results showed that both N deficiency and nitrate (NO3-) can trigger the production of hydrogen peroxide and lipid peroxidation in roots. In contrast, these responses were not altered by NH4+. Further, N deficiency and NO3--triggered redox imbalance was re-established by increased of proanthocyanidins (PAs) and glutathione (GSH), as well as upregulation of representative antioxidant enzyme activities and genes. To further explore the molecular bases of these responses, comparative transcriptome analysis was performed, and redox homeostasis-associated differentially expressed genes (DEGs) were selected for bioinformatics analysis. Most of these genes were involved in the flavonoid biosynthesis, GSH metabolism and the antioxidant system, which was specifically altered by N deficiency or NO3-. Moreover, the interplay between H2O2 (generated by RBOH and Ndufab1) and hormones (including abscisic acid, auxin, cytokinin and ethylene) in response to different N forms was suggested. Collectively, the above findings contribute to an understanding of the underlying molecular mechanisms of redox homeostasis and signalling in alleviating oxidative stress in tea plant roots.
PMID: 32605706
Environ Manage , IF:2.561 , 2020 Nov , V66 (5) : P930-939 doi: 10.1007/s00267-020-01351-z
Assessing the Plant Growth Promoting and Arsenic Tolerance Potential of Bradyrhizobium japonicum CB1809.
School of Engineering, RMIT University, Melbourne, VIC, Australia.; Department of Environmental Science and Management, North South University, Dhaka, Bangladesh.; Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka, Bangladesh.; School of Science, RMIT University, Bundoora, VIC, Australia.; School of Engineering, RMIT University, Melbourne, VIC, Australia. suzie.reichman@unimelb.edu.au.; Centre for Anthropogenic Pollution Impact and Management, School of BioSciences, University of Melbourne, Parkville, VIC, Australia. suzie.reichman@unimelb.edu.au.
Accumulation of heavy metals in soil is of concern to the agricultural production sector, because of the potential threat to food quality and quantity. Inoculation with plant growth-promoting bacteria (PGPR) has previously been shown to alleviate heavy metal stress but the mechanisms are unclear. Potential mechanisms by which inoculation with Bradyrhizobium japonicum CB1809 affected the legume soybean (Glycine max cv. Zeus) and the non-legume sunflower (Helianthus annus cv. Hyoleic 41) were investigated in solution culture under 5 muM As stress. Adding As resulted in As tissue concentrations of up to 5 mg kg(-1) (shoots) and 250 mg kg(-1) (roots) in both species but did not reduce shoot or root biomass. Inoculation increased root biomass but only in the legume (soybean) and only with As. Inoculation resulted in large (up to 100%) increases in siderophore concentration but relatively small changes (+/-10-15%) in auxin concentration in the rhizosphere. However, the increase in siderophore concentration in the rhizosphere did not result in the expected increases in tissue N or Fe, especially in soybean, suggesting that their function was different. In conclusion, siderophores and auxins may be some of the mechanisms by which both soybean and sunflower maintained plant growth in As-contaminated media.
PMID: 32918111
Insects , IF:2.22 , 2020 Nov , V11 (11) doi: 10.3390/insects11110790
Water Dipping of Auxin Coated Chrysanthemum Cuttings Confers Protection against Insect Herbivores.
Plant Sciences and Natural Products, Institute of Biology, Leiden University, 2300 RA Leiden, The Netherlands.; Business Unit Greenhouse Horticulture, Wageningen University & Research, Violierenweg 1, 2665 MV Bleiswijk, The Netherlands.; Molecular Interaction Ecology, German Center for Integrative Biodiversity Research (iDiv), Halle-Gena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany.; Institute of Biodiversity, Friedrich Schiller University Jena, Dornburger-Str. 159, 07743 Jena, Germany.
Auxins are commonly used for commercial propagation of chrysanthemums by stem cuttings. Recent studies imply that these root-promoting hormones also affect plant defense responses. The underlying motive of this study stems from the serendipitous observation that water dipping of auxin-coated cuttings beneficially affected thrips herbivory. Therefore, the primary objective of this investigation was to explore the role of indole-3-butyric acid (IBA) in relation to herbivore susceptibility in chrysanthemum. We observed contrasting findings concerning the physical presence of IBA and it's role in promoting susceptibility of cuttings to thrips, which may in part be explained by the phenotypical variations of cuttings generated from mother plants. Nonetheless, we repeatedly demonstrated considerable protection, in some experiments up to 37%, against thrips and leaf miner upon water dipping of IBA-coated cuttings. Assessment of polyphenol oxidase activity (PPO), 14 days after dipping treatment, suggests that neither direct induction nor priming of plant defenses are involved. Future experiments aimed at understanding the early signaling events may help to explain the underlying mechanisms involved in conferring herbivore protection. We propose a dual role for auxins in early integrated pest management strategies to maximize plant development and minimize herbivory through feasible, cost-effective water dipping treatments.
PMID: 33198105
Biol Open , IF:2.029 , 2020 Nov , V9 (11) doi: 10.1242/bio.055541
Uncharted routes: exploring the relevance of auxin movement via plasmodesmata.
Sainsbury Laboratory, University of Cambridge, 47 Bateman Street, Cambridge CB2 1 LR, UK andrea.paterlini@slcu.cam.ac.uk.
Auxin is an endogenous small molecule with an incredibly large impact on growth and development in plants. Movement of auxin between cells, due to its negative charge at most physiological pHs, strongly relies on families of active transporters. These proteins import auxin from the extracellular space or export it into the same. Mutations in these components have profound impacts on biological processes. Another transport route available to auxin, once the substance is inside the cell, are plasmodesmata connections. These small channels connect the cytoplasms of neighbouring plant cells and enable flow between them. Interestingly, the biological significance of this latter mode of transport is only recently starting to emerge with examples from roots, hypocotyls and leaves. The existence of two transport systems provides opportunities for reciprocal cross-regulation. Indeed, auxin levels influence proteins controlling plasmodesmata permeability, while cell-cell communication affects auxin biosynthesis and transport. In an evolutionary context, transporter driven cell-cell auxin movement and plasmodesmata seem to have evolved around the same time in the green lineage. This highlights a co-existence from early on and a likely functional specificity of the systems. Exploring more situations where auxin movement via plasmodesmata has relevance for plant growth and development, and clarifying the regulation of such transport, will be key aspects in coming years.This article has an associated Future Leader to Watch interview with the author of the paper.
PMID: 33184092
Int Microbiol , IF:1.833 , 2020 Nov , V23 (4) : P501-509 doi: 10.1007/s10123-020-00122-4
Effects of Trichoderma asperellum and its siderophores on endogenous auxin in Arabidopsis thaliana under iron-deficiency stress.
College of Life Science, Shandong Normal University, Jinan, 250014, China. zhaolei@sdu.edu.cn.; College of Life Science, Shandong Normal University, Jinan, 250014, China.
Iron (Fe) deficiency is one of the major limiting factors affecting crop yields. Trichoderma asperellum Q1, a biocontrol and plant growth promoting fungus, can produce the siderophore which has a high affinity to Fe(3+) in the absence of iron. In this study, Trichoderma asperellum Q1 was found to be able to promote growth of Arabidopsis thaliana in an iron-deficient or insoluble iron-containing (Fe2O3) medium. It also can produce more siderophore and indole-3-acetic acid (IAA) as the concentration of iron ions decreased. However, it is unclear that the relationship between siderophore and IAA in promoting plant growth. Both Trichoderma asperellum Q1 and siderophore promotes not only the DR5::GFP transgenic Arabidopsis thaliana seedlings, in which the root IAA is labeled by green fluorescent protein gene, but also increases the content of endogenous IAA in the roots, which was shown by the fluorescence study. The strongest fluorescence was observed in the treated group inoculated with Trichoderma asperellum Q1 under the condition of insoluble iron. In the case of iron-free medium, adding siderophore also increased the observed fluorescence intensity. These results suggest that the siderophores produced by Trichoderma asperellum Q1 increased the content of IAA in Arabidopsis roots by enhancing the conversion of poorly soluble iron or by the siderophore itself.
PMID: 32080772
3 Biotech , IF:1.798 , 2020 Nov , V10 (11) : P495 doi: 10.1007/s13205-020-02487-9
miRNAs as key regulators via targeting the phytohormone signaling pathways during somatic embryogenesis of plants.
Hainan Key Laboratory of Tropical Oil Crops Biology/Coconut Research Institute, Chinese Academy of Tropical Agricultural Sciences, Wenchang, 571339 Hainan People's Republic of China.grid.453499.60000 0000 9835 1415
Somatic embryogenesis is the regeneration of embryos from the somatic cell via dedifferentiation and redifferentiation without the occurrence of fertilization. A complex network of genes regulates the somatic embryogenesis process. Especially, microRNAs (miRNAs) have emerged as key regulators by affecting phytohormone biosynthesis, transport and signal transduction pathways. miRNAs are small, non-coding small RNA regulatory molecules involved in various developmental processes including somatic embryogenesis. Several types of miRNAs such as miR156, miR157, miR 159, miR 160, miR165, miR166, miR167, miR390, miR393 and miR396 have been reported to intricate in regulating somatic embryogenesis via targeting the phytohormone signaling pathways. Here we review current research progress on the miRNA-mediated regulation involved in somatic embryogenesis via regulating auxin, ethylene, abscisic acid and cytokinin signaling pathways. Further, we also discussed the possible role of other phytohormone signaling pathways such as gibberellins, jasmonates, nitric oxide, polyamines and brassinosteroids. Finally, we conclude by discussing the expression of miRNAs and their targets involved in somatic embryogenesis and possible regulatory mechanisms cross talk with phytohormones during somatic embryogenesis.
PMID: 33150121
Plant Signal Behav , IF:1.671 , 2020 Nov : P1848086 doi: 10.1080/15592324.2020.1848086
Superoxide anion generation response to wound in Arabidopsis hypocotyl cutting.
College of Life Sciences, Shaanxi Normal University , Xi'an, China.
Cutting is a frequently used model to study the process of adventitious root formation, and excision of cuttings leads to rapid wound response signaling. We recently showed that as a wound signal, reactive oxygen species (ROS, mainly hydrogen peroxide) participate in adventitious root induction of hypocotyl cuttings through regulation of auxin biosynthesis and transport. Here, superoxide anion (O2 (-*)), an early type of ROS, exhibited rapid burst at the cutting site immediately in response to wounding in Arabidopsis hypocotyl cuttings. Diphenylene iodonium chloride (DPI, inhibitor of NADPH oxidase) overwhelmingly suppressed O2 (-*) propagation through the hypocotyl. Compared to wild type, O2 (-*) burst only occur in cut base, and upward transduction were inhibited completely in NADPH oxidase mutant AtRbohD. These results indicate O2 (-*) generation and propagation in response to wound and via NADPH oxidase in adventitious root induction of hypocotyl cuttings.
PMID: 33210579
Plant Signal Behav , IF:1.671 , 2020 Nov , V15 (11) : P1813998 doi: 10.1080/15592324.2020.1813998
Nitroxin and arbuscular mycorrhizal fungi alleviate negative effects of drought stress on Sorghum bicolor yield through improving physiological and biochemical characteristics.
Department of Agriculture, Zahedan Branch, Islamic Azad University , Zahedan, Iran.
Soil microorganisms play an important role in enhancing soil fertility and plant health. Nitroxin is a bio-fertilizer that is a combination of Azospirilium and Azotobacter rhizobacteria. Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria can enhance biotic and abiotic stress tolerance in plants, whereas little is known regarding their roles in sorghum (Sorghum bicolor L.) growth under drought stress conditions. Therefore, this experiment was conducted to investigate the inoculation of grain sorghum with the bio-fertilizers of Nitroxin and Glomus mosseae effects on some physiological and biochemical traits and yield of grain sorghum under drought stress conditions in the region of Saravan, Iran, in 2017 and 2018. The results of this experiment showed that severe and moderate drought stress conditions decreased the amounts of grain protein percentage, auxin (IAA) content, root colonization, grain yield, and protein yield of grain, whereas grain starch percentage, the activity of catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) enzymes and content of total carotenoid, total anthocyanin, total flavonoid, electrolyte leakage, and malondialdehyde (MDA) were increased. Inoculation of sorghum plants with bio-fertilizers improved these traits (except starch content, electrolyte leakage, and MDA) under drought stress conditions as well as non-stress conditions. As a result, grain yield and protein yield of sorghum decreased by 43.77 and 43.99%, respectively, under severe drought stress conditions but co-inoculation with Nitroxin and AMF under severe drought stress conditions increased grain yield and protein yield of sorghum by 27 and 19.63%, respectively, compared to non-application of these bio-fertilizers. Thus, Nitroxin and AMF can be recommended for profitable sorghum production under drought stress conditions.
PMID: 32902363
Plant Signal Behav , IF:1.671 , 2020 Nov , V15 (11) : P1809847 doi: 10.1080/15592324.2020.1809847
Indeterminate domain 3 negatively regulates plant erectness and the resistance of rice to sheath blight by controlling PIN-FORMED gene expressions.
College of Plant Protection, Shenyang Agricultural University , Shenyang, China.; School of Life Science and Technology, Hubei Engineering University , Xiaogan, China.; Citrus Research Institute, Southwest University , Chongqing, China.
Plant architecture and disease resistance are the key factors that control the production of yield. However, the mechanism behind these factors is largely unknown. In this study, we identified that indeterminate domain 3 (IDD3) was obviously induced by inoculation of Rhizoctonia solani AG1-IA. Plants that overexpressed IDD3 (IDD3 OX) were more susceptible, while idd3 mutants showed a similar response to sheath blight disease compared with wild-type plants. Interestingly, IDD3 OX plants developed a wider tiller angle and exhibited altered shoot gravitropism, while idd3 knock-out mutants showed no visible morphological differences compared with the wild-type plants. IDD3 is ubiquitously expressed in different tissues and stages, and the IDD3 transcript was induced by exogenously applied auxin. Expression of the PIN-FORMED (PIN) and Aux/IAA genes was altered in IDD3 OX compared with wild-type plants. Furthermore, IDD3 OX plants are sensitive to auxin and the polar auxin transporter inhibitor N-1-naphthylphalamic acid (NPA). Further yeast-one hybrid, chromatin immunoprecipitation (ChIP) and transient assays revealed that IDD3 directly represses PIN1b via promoter binding. Inoculation with R. solani indicated that PIN1b RNAi plants are more susceptible to sheath blight disease (ShB) compared with the wild-type. Taken together, our analyses suggest that IDD3 controls plant architecture and the resistance of rice to ShB via the regulation of PIN auxin transporter genes.
PMID: 32842845
Plant Signal Behav , IF:1.671 , 2020 Nov , V15 (11) : P1805232 doi: 10.1080/15592324.2020.1805232
Strigolactone elevates ethylene biosynthesis in etiolated Arabidopsis seedlings.
Department of Botany and Plant Pathology and Center for Plant Biology, Purdue University , West Lafayette, IN, USA.
The gaseous phytohormone ethylene influences many aspects of plant life, including germination, fruit ripening, senescence, and stress responses. These diverse roles of ethylene occur in part through crosstalk with other phytohormones, which affects ethylene biosynthesis and signaling pathways. We have recently shown that the phytohormones, including gibberellic acid, abscisic acid, auxin, methyl jasmonate, and salicylic acid, regulate the stability of ACC synthases (ACSs), the rate-limiting enzymes in ethylene biosynthesis. Here, we report that treatment of etiolated Arabidopsis seedlings with strigolactone (SL) increases ethylene biosynthesis. SL does not influence ACS stability or ACS gene expression, but it increases the transcript levels of a subset of ACC oxidase (ACO) genes, thereby enhancing ethylene biosynthesis. Taken together with the results of our previous study, these findings demonstrate that most phytohormones differentially regulate ethylene biosynthesis in dark-grown Arabidopsis seedlings by affecting ACS stability and/or the transcript levels of ethylene biosynthesis genes.
PMID: 32835599
An Acad Bras Cienc , 2020 , V92 (3) : Pe20190254 doi: 10.1590/0001-3765202020190254
Low auxin sensitivity of diageotropica tomato mutant alters nitrogen deficiency response.
Universidade Estadual Paulista (UNESP), Departamento de Solos e Adubos, Faculdade de Ciencias Agrarias e Veterinaria, Via de Acesso Prof. Paulo Donato Castellane, s/n, Zona Rural, 14884-900 Jaboticabal, SP, Brazil.; Universidade de Marilia, Centro de Ciencias Agrarias, Avenida Higino Muzzy Filho, 1001, Cidade Universitaria, 17525-902 Marilia, SP, Brazil.; Universidade Estadual Paulista (UNESP), Departamento de Biologia Aplicada a Agropecuaria, Faculdade de Ciencias Agrarias e Veterinaria, Via de Acesso Prof. Paulo Donato Castellane, s/n, Zona Rural, 14884-900 Jaboticabal, SP, Brazil.
Plant responses to nitrogen supply are dependent on auxin signaling, but much still remains to be elucidated regarding N deficiency in tomato. Thus, the objective of this work was to evaluate how low auxin sensitivity regulates the responses of tomato plants to N deficiency. For this purpose, we used the tomato diageotropica mutant, with low auxin sensitivity, and a near isogenic line cv. Micro-Tom grown in nutrient solutions under absence and presence of nitrogen. Plant height, stem diameter, root and shoot dry mass, area and root density, number of lateral roots, leaf area, chlorophylls and carotenoids content, nitrogen accumulation and nitrogen use efficiency were evaluated. We observed a clear interaction between the tomato genotype and nitrogen. When the plants were grown with nitrogen, 'Micro-Tom' showed higher growth than the diageotropica mutant. Under nitrogen deficiency condition, the mutant showed improved growth, nitrogen use efficiency and higher contents of pigments. In general, the low sensitivity to auxin in diageotropica caused reduced growth in both shoot and root. However, the diageotropica tomato showed a positive regulation of the nitrogen use efficiency under nitrogen deficiency. In general, our data revealed that the reduced sensitivity to auxin increased the adaptive capacity to the nitrogen deficiency.
PMID: 33206797