Science , IF:41.845 , 2020 Oct , V370 (6516) : P550-557 doi: 10.1126/science.aba3178
Receptor kinase module targets PIN-dependent auxin transport during canalization.
Institute of Science and Technology (IST), 3400 Klosterneuburg, Austria.; Laboratory of Growth Regulators, The Czech Academy of Sciences, Institute of Experimental Botany and Palacky University, Slechtitelu 27, CZ-78371 Olomouc, Czech Republic.; Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic.; Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, Jagiellonska 28, 40-032 Katowice, Poland.; Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708 Wageningen, the Netherlands.; Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria.; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium.; VIB Center for Plant Systems Biology, 9052 Ghent, Belgium.; Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, (BOKU), Vienna, Austria.; Institute of Science and Technology (IST), 3400 Klosterneuburg, Austria. jiri.friml@ist.ac.at.
Spontaneously arising channels that transport the phytohormone auxin provide positional cues for self-organizing aspects of plant development such as flexible vasculature regeneration or its patterning during leaf venation. The auxin canalization hypothesis proposes a feedback between auxin signaling and transport as the underlying mechanism, but molecular players await discovery. We identified part of the machinery that routes auxin transport. The auxin-regulated receptor CAMEL (Canalization-related Auxin-regulated Malectin-type RLK) together with CANAR (Canalization-related Receptor-like kinase) interact with and phosphorylate PIN auxin transporters. camel and canar mutants are impaired in PIN1 subcellular trafficking and auxin-mediated PIN polarization, which macroscopically manifests as defects in leaf venation and vasculature regeneration after wounding. The CAMEL-CANAR receptor complex is part of the auxin feedback that coordinates polarization of individual cells during auxin canalization.
PMID: 33122378
Cell , IF:38.637 , 2020 Oct 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
Nat Commun , IF:12.121 , 2020 Oct , V11 (1) : P5343 doi: 10.1038/s41467-020-19140-x
MSH1-induced heritable enhanced growth vigor through grafting is associated with the RdDM pathway in plants.
Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE, USA.; Department of Biology, The Pennsylvania State University, University Park, PA, USA.; EpiCrop Technologies, Inc., Lincoln, NE, USA.; Gulf Coast Research and Education Center, IFAS, University of Florida, Wimauma, FL, USA.; Departments of Biology and Plant Science, The Pennsylvania State University, University Park, PA, USA. sam795@psu.edu.
Plants transmit signals long distances, as evidenced in grafting experiments that create distinct rootstock-scion junctions. Noncoding small RNA is a signaling molecule that is graft transmissible, participating in RNA-directed DNA methylation; but the meiotic transmissibility of graft-mediated epigenetic changes remains unclear. Here, we exploit the MSH1 system in Arabidopsis and tomato to introduce rootstock epigenetic variation to grafting experiments. Introducing mutations dcl2, dcl3 and dcl4 to the msh1 rootstock disrupts siRNA production and reveals RdDM targets of methylation repatterning. Progeny from grafting experiments show enhanced growth vigor relative to controls. This heritable enhancement-through-grafting phenotype is RdDM-dependent, involving 1380 differentially methylated genes, many within auxin-related gene pathways. Growth vigor is associated with robust root growth of msh1 graft progeny, a phenotype associated with auxin transport based on inhibitor assays. Large-scale field experiments show msh1 grafting effects on tomato plant performance, heritable over five generations, demonstrating the agricultural potential of epigenetic variation.
PMID: 33093443
Curr Biol , IF:9.601 , 2020 Oct doi: 10.1016/j.cub.2020.09.037
A WOX/Auxin Biosynthesis Module Controls Growth to Shape Leaf Form.
Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, 50829 Cologne, Germany.; Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umea, Sweden; Laboratory of Growth Regulators, Institute of Experimental Botany of the Czech Academy of Sciences and Faculty of Science of Palacky University, Slechtitelu 27, 78371 Olomouc, Czech Republic.; Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umea, Sweden.; Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, 50829 Cologne, Germany. Electronic address: tsiantis@mpipz.mpg.de.
A key challenge in biology is to understand how the regional control of cell growth gives rise to final organ forms. Plant leaves must coordinate growth along both the proximodistal and mediolateral axes to produce their final shape. However, the cell-level mechanisms controlling this coordination remain largely unclear. Here, we show that, in A. thaliana, WOX5, one of the WUSCHEL-RELATED HOMEOBOX (WOX) family of homeobox genes, acts redundantly with WOX1 and WOX3 (PRESSED FLOWER [PRS]) to control leaf shape. Through genetics and hormone measurements, we find that these WOXs act in part through the regional control of YUCCA (YUC) auxin biosynthetic gene expression along the leaf margin. The requirement for WOX-mediated YUC expression in patterning of leaf shape cannot be bypassed by the epidermal expression of YUC, indicating that the precise domain of auxin biosynthesis is important for leaf form. Using time-lapse growth analysis, we demonstrate that WOX-mediated auxin biosynthesis organizes a proximodistal growth gradient that promotes lateral growth and consequently the characteristic ellipsoid A. thaliana leaf shape. We also provide evidence that WOX proteins shape the proximodistal gradient of differentiation by inhibiting differentiation proximally in the leaf blade and promoting it distally. This regulation allows sustained growth of the blade and enables a leaf to attain its final form. In conclusion, we show that the WOX/auxin regulatory module shapes leaf form by coordinating growth along the proximodistal and mediolateral leaf axes.
PMID: 33035489
Curr Biol , IF:9.601 , 2020 Oct doi: 10.1016/j.cub.2020.09.036
Intrinsic Cell Polarity Coupled to Growth Axis Formation in Tobacco BY-2 Cells.
John Innes Centre, Colney Lane, Norwich NR4 7UH, UK. Electronic address: jordi.chan@jic.ac.uk.; John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.; John Innes Centre, Colney Lane, Norwich NR4 7UH, UK. Electronic address: enrico.coen@jic.ac.uk.
Several plant proteins are preferentially localized to one end of a cell, allowing a polarity to be assigned to the cell. These cell polarity proteins often exhibit coordinated patterns between neighboring cells, termed tissue cell polarity. Tissue cell polarity is widespread in plants and can influence how cells grow, divide, and differentiate [1-5]. However, it is unclear whether cell polarity is established through cell-intrinsic or -extrinsic mechanisms and how polarity is coupled to growth. To address these issues, we analyzed the behavior of a tissue cell polarity protein BASL (BREAKING OF ASYMMETRY IN THE STOMATAL LINEAGE) in the simplifying context of cultured cell filaments and in protoplasts before and during regeneration. We show that BASL is polarly localized when ectopically expressed in tobacco BY-2 cell cultures. Ectopic BASL is found preferentially at the developing tips of cell filaments, likely marking a polarized molecular address. Polarity can shift during the cell cycle and is resistant to treatment with microtubule, actin or auxin transport inhibitors. BASL also exhibits polar localization in spherical protoplasts, in contrast to other polarity proteins so far tested. BASL polarity within protoplasts is dynamic and resistant to auxin transport inhibitors. As protoplasts regenerate, polarity remains dynamic in isotropically growing cells but becomes fixed in anisotropic cells and aligns with the axis of cell growth. Our findings suggest that plant cells have an intrinsic ability to polarize and that environmental or developmental cues may act by biasing the direction of this polarity and thus the orientation of anisotropic growth.
PMID: 33035485
Curr Biol , IF:9.601 , 2020 Oct , V30 (19) : P3880-3888.e5 doi: 10.1016/j.cub.2020.07.055
HEARTBREAK Controls Post-translational Modification of INDEHISCENT to Regulate Fruit Morphology in Capsella.
Crop Genetics Department, John Innes Centre, Norwich NR4 7UH, UK.; Cell and Developmental Biology Department, John Innes Centre, Norwich NR4 7UH, UK.; Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83 Umea, Sweden.; Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, 106 91 Stockholm, Sweden.; Department of Biosciences, University of Durham, Durham DH1 3LE, UK.; Crop Genetics Department, John Innes Centre, Norwich NR4 7UH, UK. Electronic address: lars.ostergaard@jic.ac.uk.
Morphological variation is the basis of natural diversity and adaptation. For example, angiosperms (flowering plants) evolved during the Cretaceous period more than 100 mya and quickly colonized terrestrial habitats [1]. A major reason for their astonishing success was the formation of fruits, which exist in a myriad of different shapes and sizes [2]. Evolution of organ shape is fueled by variation in expression patterns of regulatory genes causing changes in anisotropic cell expansion and division patterns [3-5]. However, the molecular mechanisms that alter the polarity of growth to generate novel shapes are largely unknown. The heart-shaped fruits produced by members of the Capsella genus comprise an anatomical novelty, making it particularly well suited for studies on morphological diversification [6-8]. Here, we show that post-translational modification of regulatory proteins provides a critical step in organ-shape formation. Our data reveal that the SUMO protease, HEARTBREAK (HTB), from Capsella rubella controls the activity of the key regulator of fruit development, INDEHISCENT (CrIND in C. rubella), via de-SUMOylation. This post-translational modification initiates a transduction pathway required to ensure precisely localized auxin biosynthesis, thereby facilitating anisotropic cell expansion to ultimately form the heart-shaped Capsella fruit. Therefore, although variation in the expression of key regulatory genes is known to be a primary driver in morphological evolution, our work demonstrates how other processes-such as post-translational modification of one such regulator-affects organ morphology.
PMID: 32795439
J Hazard Mater , IF:9.038 , 2020 Oct : P124250 doi: 10.1016/j.jhazmat.2020.124250
Auxin metabolic network regulates the plant response to metalloids stress.
Department of Biotechnology, Indian Institute of Technology, Roorkee 247667, Uttarakhand, India.; National Center for Soybean Improvement, Key L aboratory of Biology and Genetics and Breeding for Soybean, Ministry of Agriculture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.; Plant Physiology Laboratory, Department of Botany, C.M.P. Degree College, University of Allahabad, Prayagraj 211002, India.; Department of Biochemistry, Cell and Molecular Biology, Estacion Experimental del Zaidin, Consejo Superior de Investigaciones Cientificas (CSIC), C/Profesor Albareda, 1, 18008 Granada, Spain.; Department of Biotechnology, Indian Institute of Technology, Roorkee 247667, Uttarakhand, India. Electronic address: shri.yadav@bt.iitr.ac.in.
Metalloids are among the major pollutants posing a risk to the environment and global food security. Plant roots uptake these toxic metalloids from the soil along with other essential minerals. Plants respond to metalloid stress by regulating the distribution and levels of various endogenous phytohormones. Recent research showed that auxin is instrumental in mediating resilience to metalloid-induced stress in plants. Exogenous supplementation of the auxin or plant growth-promoting micro-organisms (PGPMs) alleviates metalloid uptake, localization, and accumulation in the plant tissues, thereby improving plant growth under metalloid stress. Moreover, auxin triggers various biological responses such as the production of enzymatic and non-enzymatic antioxidants to combat nitro-oxidative stress induced by the metalloids. However, an in-depth understanding of the auxin stimulated molecular and physiological responses to the metalloid toxicity needs to be investigated in future studies. The current review attempts to provide an update on the recent advances and the current state-of-the-art associated with auxin and metalloid interaction, which could be used as a start point to develop biotechnological tools and create an eco-friendly environment.
PMID: 33109410
New Phytol , IF:8.512 , 2020 Oct doi: 10.1111/nph.16943
Arabidopsis AZG2 transports cytokinins in vivo and regulates lateral root emergence.
Instituto Multidisciplinario de Biologia Vegetal (IMBIV), CONICET, Av. Velez Sarsfield 299, Cordoba, 5000, Argentina.; Zentrum fur Molekularbiologie der Pflanzen, Universitat Tubingen, Auf der Morgenstelle 1, Tubingen, 72076, Germany.; Facultad de Ciencias Exactas Fisicas y Naturales, Universidad Nacional de Cordoba, Av. Velez Sarsfield 299, Cordoba, 5000, Argentina.; Institut fur Molekulare Physiologie und Biotechnologie der Pflanzen, Abteilung Molekulare Pflanzenphysiologie, Universitat Bonn, Kirschallee 1, Bonn, 53115, Germany.
Cytokinin and auxin are key regulators of plant growth and development. During the last decade transport mechanisms have turned out to be the key for the control of local and long-distance hormone distributions. In contrast with auxin, cytokinin transport is poorly understood. Here, we show that Arabidopsis thaliana AZG2, a member of the AZG purine transporter family, acts as cytokinin transporter involved in root system architecture determination. Even though purines are substrates for both AZG1 and AZG2, we found distinct transport mechanisms. The expression of AZG2 is restricted to a small group of cells surrounding the lateral root (LR) primordia and induced by auxins. Compared to the wild-type (WT), mutants carrying loss-of-function alleles of AZG2 have higher LR density, suggesting that AZG2 is part of a regulatory pathway in LR emergence. Moreover, azg2 is partially insensitive to exogenous cytokinin, which is consistent with the observation that the cytokinin reporter TCSnpro :GFP showed lower fluorescence signal in the roots of azg2 compared to the WT. These results indicate a defective cytokinin signalling pathway in the region of LR primordia. The integration of AZG2 subcellular localization and cytokinin transport capacity data allowed us to propose a local cytokinin : auxin signalling model for the regulation of LR emergence.
PMID: 33070379
New Phytol , IF:8.512 , 2020 Oct doi: 10.1111/nph.16978
Apple SUMO E3 ligase MdSIZ1 facilitates SUMOylation of MdARF8 to regulate lateral root formation.
State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, Shandong Agricultural University, Tai-An, Shandong, 271018, China.; State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Landscaping, Ministry of Agriculture and Rural Affairs, College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China.
Post-translational modification of proteins mediated by SIZ1, a small ubiquitin-like modifier (SUMO) E3 ligase, regulates multiple biological processes in plants. However, its role in the regulation of lateral root formation remains unclear. Here, we demonstrate that the apple SUMO E3 ligase MdSIZ1 promotes lateral root formation. Using a yeast-two-hybrid (Y2H) system, the auxin response factor MdARF8 was screened out as a protein-protein interaction partner of the SUMO-conjugating E2 enzyme MdSCE1, indicating that MdARF8 may be a substrate for MdSIZ1. The interaction between MdARF8 and MdSCE1 was confirmed by pull-down, Y2H and Co-immunoprecipitation assays. MdSIZ1 enhanced the conjugating enzyme activity of MdSCE1 to form a MdSCE1-MdSIZ1-MdARF8 complex, thereby facilitating SUMO modification. We identified two arginine substitution mutations at K342 and K380 in MdARF8 that blocked MdSIZ1-mediated SUMOylation, indicating that K342 and K380 are the principal SUMOylation sites of the MdARF8 protein. Moreover, MdARF8 promoted lateral root formation in transgenic apple plants, and the phenotype of reduced lateral roots in the Arabidopsis siz1-2 mutant was restored in siz1-2/MdARF8 complementary plants. Our findings reveal an important role for sumoylation in the regulation of lateral root formation in plants.
PMID: 33006771
Plant Physiol , IF:6.902 , 2020 Oct doi: 10.1104/pp.20.00632
Towards "smart canopy" sorghum: discovery of the genetic control of leaf angle across layers.
Bayer CITY: St Louis STATE: MO United States Of America [US].; Iowa State University CITY: Ames STATE: IA United States Of America [US].; Iowa State Univerisity CITY: Ames STATE: IA United States Of America [US].; Iowa State University 2035B Carver Co-Laboratory CITY: Ames STATE: Iowa POSTAL_CODE: 50011-3650 United States Of America [US].; Iowa State University CITY: Ames STATE: IA POSTAL_CODE: 50011 United States Of America [US] mgsalas@iastate.edu.
A "smart canopy" ideotype has been proposed with leaves being upright at the top and more horizontal towards the bottom of the plant to maximize light interception and conversion efficiencies, and thus increasing yield. The genetic control of leaf angle has to date been studied on one or two leaves, or data have been merged from multiple leaves to generate average values. This approach has limited our understanding of the diversity of leaf angles across layers and their genetic control. Genome wide association studies (GWAS) and quantitative trait loci (QTL) mapping studies in sorghum (Sorghum bicolor) were performed using layer-specific angle data collected manually and via high-throughput phenotyping strategies. The observed distribution of angles in indoor and field settings is opposite to the ideotype. Several genomic regions were associated with leaf angle within layers or across the canopy. The expression of the brassinosteroid-related transcription factor BZR1/BES1 and the auxin-transporter Dw3 were found to be highly correlated with the distribution of angles at different layers. The application of a BR biosynthesis inhibitor could not revert the undesirable overall angle distribution. These discoveries demonstrate that the exploitation of layer-specific QTL/genes will be instrumental to reversing the natural angle distribution in sorghum according to the "smart canopy" ideotype.
PMID: 33093232
Plant Physiol , IF:6.902 , 2020 Oct doi: 10.1104/pp.20.00474
Microtubule-associated protein CLASP is translationally regulated in light-dependent root apical meristem growth.
The University of British Columbia CITY: Vancouver STATE: BC Canada [CA].; The University of British Columbia CITY: Vancouver STATE: BC POSTAL_CODE: V6T 1Z4 Canada [CA] geoffrey.wasteneys@ubc.ca.
The ability for plant growth to be optimized, either in the light or dark, depends on the intricate balance between cell division and differentiation in specialized regions called meristems. When Arabidopsis thaliana seedlings are grown in the dark, hypocotyl elongation is promoted, whereas root growth is greatly reduced as a result of changes in hormone transport and a reduction in meristematic cell proliferation. Previous work showed that the microtubule-associated protein CLASP sustains root apical meristem (RAM) size by influencing microtubule (MT) organization and by modulating the brassinosteroid (BR) signalling pathway. Here, we investigated whether CLASP is involved in light-dependent root growth promotion, since dark-grown seedlings have reduced RAM activity that is observed in the clasp-1 null mutant. We showed that CLASP protein levels were greatly reduced in the root tips of dark-grown seedlings, which could be reversed by exposing plants to light. We confirmed that removing seedlings from the light led to a discernible shift in MT organization from bundled arrays, which are prominent in dividing cells, to transverse orientations typically observed in cells that have exited the meristem. BR receptors and auxin transporters, both of which are sustained by CLASP, were largely degraded in the dark. Interestingly, we found that despite the lack of protein, CLASP transcript levels were higher in dark-grown root tips. Together, these findings uncover a mechanism that sustains meristem homeostasis through CLASP, and advances our understanding of how roots modulate their growth according to the amount of light and nutrients perceived by the plant.
PMID: 33023938
Plant J , IF:6.141 , 2020 Oct doi: 10.1111/tpj.15026
OsWUS promotes tiller bud growth by establishing weak apical dominance in rice.
State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China.; College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.; State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China.
Two branching strategies are exhibited in crops: enhanced apical dominance, as in maize, or weak apical dominance, as in rice. However, the underlying mechanism of weak apical dominance remains elusive. OsWUS, an ortholog of Arabidopsis WUSCHEL (WUS) in rice, is required for tiller development. In this study, we identified and functionally characterized a low-tillering mutant decreased culm number 1 (dc1) that resulted from loss-of-function of OsWUS. The dc1 tiller buds are viable but repressed by the main culm apex, leading to stronger apical dominance than that of the wild type. Auxin response is enhanced in the dc1 mutant and knocking out the auxin action-associated gene ABERRANT SPIKELET AND PANICLE 1 (ASP1) de-repressed growth of the tiller buds in the dc1 mutant, suggesting that OsWUS and ASP1 are both involved in outgrowth of the rice tiller bud. Decapitation triggers higher contents of cytokinins in the shoot base of the dc1 mutant compared with those in the wild type, and exogenous application of cytokinin is not sufficient for sustained growth of the dc1 tiller bud. Transcriptome analysis indicated that expression levels of transcription factors putatively bound by ORYZA SATIVA HOMEOBOX 1 (OSH1) are changed in response to decapitation and display a greater fold change in the dc1 mutant than that in the wild type. Collectively, these findings reveal an important role of OsWUS in tiller bud growth by influencing apical dominance and provide the basis for an improved understanding of tiller bud development in rice.
PMID: 33064890
Plant J , IF:6.141 , 2020 Oct doi: 10.1111/tpj.15024
The ESCRT-I components VPS28A and VPS28B are essential for auxin-mediated plant development.
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.; University of Chinese Academy of Sciences, Beijing, 100049, China.; Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China.
The highly conserved ESCRT pathway plays critical roles in endosomal sorting of ubiquitinated plasma membrane proteins for degradation. However, the functions of many components of the ESCRT machinery in plants remain unsolved. Here we show that the ESCRT-I subunits VPS28A and VPS28B are functionally redundant and required for embryo development in Arabidopsis. We conducted a screen for genetic enhancers of pid, which is defective in auxin signaling and transport. We isolated a no--cotyledon in pid 104 (ncp104) mutant, which failed to develop cotyledons in pid background. We discovered that ncp104 was a unique recessive gain-of-function allele of vps28a. VPS28A and VPS28B were expressed during embryogenesis and the proteins were localized to trans-Golgi network/early endosome (TGN/EE) and post Golgi/endosomal compartments, consistent to their functions in endosomal sorting and embryogenesis. The single vps28a and vps28b loss-of-function mutants did not display obvious developmental defects, but their double mutants showed abnormal cell division patterns and were arrested at the globular embryo stage. The vps28a vps28b double mutants showed altered auxin responses, disrupted PIN1-GFP expression patterns and abnormal PIN1-GFP accumulation in small aberrant vacuoles. The ncp104 mutation may cause the VPS28A protein unstable and/or toxic. Taken together, our findings demonstrate that the ESCRT-I components VPS28A and VPS28B redundantly play essential roles in vacuole formation, endosomal sorting of plasma membrane proteins and auxin-mediated plant development.
PMID: 33058303
J Exp Bot , IF:5.908 , 2020 Oct doi: 10.1093/jxb/eraa495
The conserved brassinosteroid-related transcription factor BIM1a negatively regulates fruit growth in tomato.
INRAE, Univ. Bordeaux, UMR BFP, Villenave d'Ornon, France.; Instituto de Biotecnologia, Instituto Nacional de Tecnologia Agropecuaria, Consejo Nacional de Investigaciones Cientificas y Tecnicas, Castelar, Argentina.; Department of Plant Life Science, Faculty of Agriculture, Ryukoku University, Otsu, Shiga, Japan.; Department of Natural Sciences, International Christian University, Tokyo, Japan.; Faculty of Life and Environmental Sciences, University of Tsukuba, Tskuba, Japan.; Tsukuba Plant Innovation Research Center, University of Tsukuba, Tskuba, Japan.
Brassinosteroids (BRs) are steroid hormones that play key roles in plant development and defense. Our goal is to harness the extensive knowledge of the Arabidopsis BR signalling network for improving productivity in crop species. This first requires identifying components of the conserved network and their function in the target species. Here, we investigated the function of SlBIM1a, the closest tomato homolog of AtBIM1, which is highly expressed in fruit. SlBIM1a overexpressing lines displayed severe plant and fruit dwarfism, and histological characterization of different transgenic lines revealed that SlBIM1a expression negatively correlated with fruit pericarp cell size, resulting in fruit size modifications. These growth phenotypes were in contrast to those found in Arabidopsis, and this was confirmed by the reciprocal ectopic expression of SlBIM1a/b in Arabidopsis and, AtBIM1 in tomato. These results determined that BIM1 function depends more on the recipient species than on its primary sequence. Yeast two-hybrid interaction studies and transcriptomic analyses of SlBIM1a overexpressing fruit, further suggested that SlBIM1a acts through its interaction with SlBZH1 to govern the transcriptional regulation of growth-related BRs target genes. Together, these results suggest that SlBIM1a is a negative regulator of pericarp cell expansion, possibly at the crossroad with auxin and light signalling.
PMID: 33097930
J Exp Bot , IF:5.908 , 2020 Oct doi: 10.1093/jxb/eraa488
Silicon induces adventitious root formation in rice (Oryza sativa L.) under arsenate stress with the involvement of nitric oxide and indole-3-acetic acid.
Amity Institute of Organic Agriculture (AIOA), Amity University, Noida, Sector, Noida, Uttar Pradesh.; Department of Biotechnology, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, India.; Environmental Research and Innovation Department, Luxembourg Institute of Science and Technology, Hautcharage, Luxembourg.; Group of Antioxidants, Free Radicals and Nitric Oxide in Biotechnology, Food and Agriculture, Department of Biochemistry and Cell and Molecular Biology of Plants, Estacion Experimental del Zaidin, Consejo Superior de Investigaciones Cientificas (CSIC), Profesor Albareda, Granada, Spain.; Plant Physiology Laboratory, Department of Botany, C.M.P. Degree College, A Constituent Post Graduate College of University of Allahabad, Allahabad, India.
Arsenic (As) negatively affects plant development. Using rice as a model, this study evaluates how the application of silicon (10 microM Si) can favour the formation of adventitious roots under arsenate stress (50 microM As V) as a mechanism to mitigate its negative effects. Indeed, the simultaneous application of As V and Si up-regulated the expression of genes involved in nitric oxide (NO) metabolism (OsNOA1), cell cycle progression (G2-M, OsCDKA1), auxin (IAA, indole-3-acetic acid) biosynthesis (OsYUCCA1 and OsTAA1) and transport (OsPIN1, OsPIN5 and OsPIN10) and Si uptake (OsLsi1 and OsLsi2), which accompanied adventitious root formation. Furthermore, Si triggered the expression and activity of MDHAR and DHAR involved in ascorbate recycling. The treatment with L-NAME, an inhibitor of NO generation, significantly suppressed adventitious root formation, even in the presence of Si; however, supplying NO in the growth media rescued its effects. The data obtained suggest that both NO and IAA are essential for Si-mediated adventitious root formation under As V stress. Interestingly, TIBA (a polar auxin transport inhibitor) suppressed adventitious root formation, even in the presence of Si and SNP (an NO donor), suggesting that Si is involved in a mechanism whereby a cellular signal is triggered and requires NO formation first and, then, IAA.
PMID: 33095869
J Exp Bot , IF:5.908 , 2020 Oct doi: 10.1093/jxb/eraa485
Endogenous indole-3-acetamide levels contribute to the crosstalk between auxin and ABA, and trigger plant stress responses in Arabidopsis thaliana.
Centro de Biotecnologia y Genomica de Plantas, Universidad Politecnica de Madrid (UPM) Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (INIA), Pozuelo de Alarcon, Spain.; Lehrstuhl fur Pflanzenphysiologie, Ruhr-Universitat Bochum, Bochum, Germany.; Department of Earth Sciences, University of Gothenburg, Gothenburg, Sweden.; Gothenburg Global Biodiversity Centre, Gothenburg, Sweden.; Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.; Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.; Departamento de Biotecnologia-Biologia Vegetal, Escuela Tecnica Superior de Ingenieria Agronomica, Alimentaria y de Biosistemas, Universidad Politecnica de Madrid (UPM), Madrid, Spain.
The evolutionary success of plants relies to a large extent on their extraordinary ability to adapt to changes in their environment. These adaptations require that plants balance their growth with their stress responses. Plant hormones are crucial mediators orchestrating the underlying adaptive processes. However, whether and how the growth-related hormone auxin and the stress-related hormones jasmonic acid (JA), salicylic acid, and abscisic acid (ABA) are coordinated remains largely elusive. Here, we analyze the physiological role of AMIDASE 1 (AMI1) in plant growth and its possible connection to plant adaptations to abiotic stresses. AMI1 contributes to cellular auxin homeostasis by catalyzing the conversion of indole-acetamide into the major plant auxin indole-3-acetic acid. Functional impairment of AMI1 increases the plants' stress status rendering mutant plants more susceptible to abiotic stresses. Transcriptomic analysis of ami1 mutants disclosed the reprogramming of a considerable number of stress-related genes, including JA and ABA biosynthesis genes. The ami1 mutants exhibit only moderately repressed growth, but an enhanced ABA accumulation, which suggests a role for AMI1 in the crosstalk between auxin and ABA. Altogether, our results suggest that AMI1 is involved in coordinating the trade-off between plant growth and stress responses, balancing auxin with ABA homeostasis.
PMID: 33068437
J Exp Bot , IF:5.908 , 2020 Oct , V71 (19) : P5865-5879 doi: 10.1093/jxb/eraa321
N-glycosylation is involved in stomatal development by modulating the release of active abscisic acid and auxin in Arabidopsis.
State Key Laboratory of Pharmaceutical Biotechnology, NJU Advanced Institute for Life Sciences (NAILS), School of Life Sciences, Nanjing University, Nanjing, China.
Asparagine-linked glycosylation (N-glycosylation) is one of the most important protein modifications in eukaryotes, affecting the folding, transport, and function of a wide range of proteins. However, little is known about the roles of N-glycosylation in the development of stomata in plants. In the present study, we provide evidence that the Arabidopsis stt3a-2 mutant, defective in oligosaccharyltransferase catalytic subunit STT3, has a greater transpirational water loss and weaker drought avoidance, accompanied by aberrant stomatal distribution. Through physiological, biochemical, and genetic analyses, we found that the abnormal stomatal density of stt3a-2 was partially attributed to low endogenous abscisic acid (ABA) and auxin (IAA) content. Exogenous application of ABA or IAA could partially rescue the mutant's salt-sensitive and abnormal stomatal phenotype. Further analyses revealed that the decrease of IAA or ABA in stt3a-2 seedlings was associated with the underglycosylation of beta-glucosidase (AtBG1), catalysing the conversion of conjugated ABA/IAA to active hormone. Our results provide strong evidence that N-glycosylation is involved in stomatal development and participates in abiotic stress tolerance by modulating the release of active plant hormones.
PMID: 32649744
Ecotoxicol Environ Saf , IF:4.872 , 2020 Oct , V203 : P111054 doi: 10.1016/j.ecoenv.2020.111054
Effects of zero-valent iron nanoparticles and quinclorac coexposure on the growth and antioxidant system of rice (Oryza sativa L.).
College of Resources and Environment, Hunan Agricultural University, Changsha, 410128, PR China.; Soil and Fertilizer Institute of Hunan Province, Hunan Academy of Agricultural Sciences, Changsha, 410125, PR China. Electronic address: Haiyongwu@163.com.; College of Resources and Environment, Hunan Agricultural University, Changsha, 410128, PR China. Electronic address: Rose850101@163.com.
Quinclorac (3,7-dichloroquinoline-8-carboxylic acid, QNC) is a highly selective auxin herbicide that is typically applied to paddy rice fields. Its residue is a serious problem in crop rotations. In this study, Oryza sativa L. seedlings was used as a model plant to explore its biochemical response to abiotic stress caused by QNC and nZVI coexposure, as well as the interactions between QNC and nZVI treatments. Exposure to 5 and 10 mg/L QNC reduced the fresh biomass by 26.6% and 33.9%, respectively, compared to the control. The presence of 50 and 250 mg/L nZVI alleviated the QNC toxicity, but the nZVI toxicity was aggravated by the coexist of QNC. Root length was enhanced upon exposure to low or medium doses of both QNC and nZVI, whereas root length was inhibited under high-dose coexposure. Both nZVI and QNC, either alone or in combination, significantly inhibited the biosynthesis of chlorophyll, and the inhibition rate increased with elevated nZVI and QNC concentration. It was indicated that nZVI or QNC can affect the plant photosynthesis, and there was a significant interaction between the two treatments. Effects of QNC on the antioxidant response of Oryza sativa L. differed in the shoots and roots; generally, the introduction of 50 and 250 mg/L nZVI alleviated the oxidative stress (POD in shoots, SOD and MDA in roots) induced by QNC. However, 750 mg/kg nZVI seriously damaged Oryza sativa L. seedlings, which likely resulted from active iron deficiency. QNC could be removed from the culture solution by nZVI; as a result, nZVI suppressed QNC uptake by 20%-30%.
PMID: 32888616
Int J Mol Sci , IF:4.556 , 2020 Oct , V21 (21) doi: 10.3390/ijms21217934
Molecular Mechanisms Underlying Sugarcane Response to Aluminum Stress by RNA-Seq.
Functional Genomics Lab, Biotechnology Department, University of Ribeirao Preto, Ribeirao Preto, SP 14096-900, Brazil.; School of Agricultural and Veterinarian Sciences, Sao Paulo State University (UNESP), Jaboticabal, SP 14884-900, Brazil.; Center for Biotechnology and Genomics, Texas Tech University, Lubbock, TX 79409, USA.; Hartwell Center, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.; AUA College of Medicine, Jabberwock Rd., P.O. Box 1451, Osbourn, Antigua and Barbuda.
Some metals are beneficial to plants and contribute to critical physiological processes. Some metals, however, are not. The presence of aluminum ions (Al(3+)) can be very toxic, especially in acidic soils. Considerable parts of the world's arable land are acidic in nature; mechanistically elucidating a plant's response to aluminum stress is critical to mitigating this stress and improving the quality of plants. To identify the genes involved in sugarcane response to aluminum stress, we generated 372 million paired-end RNA sequencing reads from the roots of CTC-2 and RB855453, which are two contrasting cultivars. Data normalization resulted in 162,161 contigs (contiguous sequences) and 97,335 genes from a de novo transcriptome assembly (trinity genes). A total of 4858 and 1307 differently expressed genes (DEGs) for treatment versus control were identified for the CTC-2 and RB855453 cultivars, respectively. The DEGs were annotated into 34 functional categories. The majority of the genes were upregulated in the CTC-2 (tolerant cultivar) and downregulated in RB855453 (sensitive cultivar). Here, we present the first root transcriptome of sugarcane under aluminum stress. The results and conclusions of this study are a crucial launch pad for future genetic and genomic studies of sugarcane. The transcriptome analysis shows that sugarcane tolerance to aluminum may be explained by an efficient detoxification mechanism combined with lateral root formation and activation of redox enzymes. We also present a hypothetical model for aluminum tolerance in the CTC-2 cultivar.
PMID: 33114621
Int J Mol Sci , IF:4.556 , 2020 Oct , V21 (19) doi: 10.3390/ijms21197314
Roles of ASYMMETRIC LEAVES2 (AS2) and Nucleolar Proteins in the Adaxial-Abaxial Polarity Specification at the Perinucleolar Region in Arabidopsis.
Graduate School of Bioscience and Biotechnology, Chubu University, 1200, Matsumoto-cho, Kasugai, Aichi 487-8501, Japan.; Graduate School of Medical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan.; Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
Leaves of Arabidopsis develop from a shoot apical meristem grow along three (proximal-distal, adaxial-abaxial, and medial-lateral) axes and form a flat symmetric architecture. ASYMMETRIC LEAVES2 (AS2), a key regulator for leaf adaxial-abaxial partitioning, encodes a plant-specific nuclear protein and directly represses the abaxial-determining gene ETTIN/AUXIN RESPONSE FACTOR3 (ETT/ARF3). How AS2 could act as a critical regulator, however, has yet to be demonstrated, although it might play an epigenetic role. Here, we summarize the current understandings of the genetic, molecular, and cellular functions of AS2. A characteristic genetic feature of AS2 is the presence of a number of (about 60) modifier genes, mutations of which enhance the leaf abnormalities of as2. Although genes for proteins that are involved in diverse cellular processes are known as modifiers, it has recently become clear that many modifier proteins, such as NUCLEOLIN1 (NUC1) and RNA HELICASE10 (RH10), are localized in the nucleolus. Some modifiers including ribosomal proteins are also members of the small subunit processome (SSUP). In addition, AS2 forms perinucleolar bodies partially colocalizing with chromocenters that include the condensed inactive 45S ribosomal RNA genes. AS2 participates in maintaining CpG methylation in specific exons of ETT/ARF3. NUC1 and RH10 genes are also involved in maintaining the CpG methylation levels and repressing ETT/ARF3 transcript levels. AS2 and nucleolus-localizing modifiers might cooperatively repress ETT/ARF3 to develop symmetric flat leaves. These results raise the possibility of a nucleolus-related epigenetic repression system operating for developmental genes unique to plants and predict that AS2 could be a molecule with novel functions that cannot be explained by the conventional concept of transcription factors.
PMID: 33022996
J Agric Food Chem , IF:4.192 , 2020 Oct , V68 (43) : P11987-11996 doi: 10.1021/acs.jafc.0c04466
Brassinosteroid Regulates 3-Hydroxy-3-methylglutaryl CoA Reductase to Promote Grape Fruit Development.
College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.; China Wine Industry Technology Institute, Yinchuan 750000, China.
Brassinosteroids (BRs) are known to regulate plant growth and development. However, only little is known about their mechanism in the regulation of berry development in grapes. This study demonstrates that BR treatment enhances the accumulation of fruit sugar components, reduces the content of organic acids (e.g., tartaric acid), promotes coloration, and increases the anthocyanin content in grape berries at the onset of the veraison, half veraison, and full veraison stages at the rate of 0.0998, 0.0560, and 0.0281 mg.g(-1), respectively. In addition, BR treatment was also found to accelerate the biosynthesis of terpenoid aroma components, such as alpha-pinene, d-limonene, and gamma-terpinene, which influence the aromatic composition of grapes. BRs can negatively regulate the expression of VvHMGR, a key gene involved in the mevalonate (MVA) pathway, and reduce the activity of 3-hydroxy-3-methylglutaryl CoA reductase (HMGR). Inhibiting the expression of HMGR promoted the accumulation of anthocyanins and fruit coloration. Meanwhile, after the inhibition, the contents of auxin indole-3-acetic acid (IAA), abscisic acid (ABA), and brassinosteroid (BR) increased, while gibberellin (GA3) and zeatin riboside (ZR) decreased, and its aromatic composition also changed. Therefore, it may be concluded that BRs inhibited HMGR activity and cooperated with VvHMGR to regulate the formation of color, aroma, and other quality characteristics in fruits.
PMID: 33059448
Plant Cell Physiol , IF:4.062 , 2020 Oct doi: 10.1093/pcp/pcaa134
The Molecular Basis of Age-modulated Plant de novo Root Regeneration Decline in Arabidopsis thaliana.
College of Life Sciences, Nanjing Normal University, Nanjing, China.
Plants possess a regeneration capacity that enables them to survive after wounding. For example, detached Arabidopsis thaliana leaves are able to form adventitious roots from their cutting sites even in the absence of exogenous hormone supplements; as process termed de novo root regeneration (DNRR). Wounding rapidly induces auxin biosynthesis at the cutting sites and then elicits a signaling cascade to promote cell fate transitions and finally generate the adventitious roots. However, rooting rates in older plants are much lower than in younger leaf explants. In this review, we highlight the recent breakthroughs in the understanding of DNRR decay in older plants from at least two independent signaling routes: (1) via the accumulation of EIN3 protein in older plants, which directly suppresses expression of WUSCHEL RELATED HOMEOBOX (WOX) genes to inhibit rooting; (2) the miR156-SPLs-AP2/ERFs pathway, which modulates root regeneration by reducing auxin biosynthesis.
PMID: 33079183
Plant Cell Physiol , IF:4.062 , 2020 Oct doi: 10.1093/pcp/pcaa131
LAZY1 Controls Tiller Angle and Shoot Gravitropism by Regulating the Expression of Auxin Transporters and Signaling Factors in Rice.
Rice Research Institute, Shenyang Agricultural University.
Tiller angle is a key factor determining rice plant architecture, planting density, light interception, photosynthetic efficiency, disease resistance, and grain yield. However, the mechanisms underlying tiller angle control are far from clear. In this study, we identified a mutant, termed bta1-1, with an enlarged tiller angle throughout its life cycle. A detailed analysis reveals that BTA1 has multiple functions because tiller angle, shoot gravitropism, and tolerance to drought stress are changed in bta1-1 plants. Moreover, BTA1 is a positive regulator of shoot gravitropism in rice. Shoot responses to gravistimulation are disrupted in bta1-1 under both light and dark conditions. Gene cloning reveals that bta1-1 is a novel mutant allele of LA1 renamed la1-SN. LA1 is able to rescue the tiller angle and shoot gravitropism defects observed in la1-SN. The nuclear localization signal of LA1 is disrupted by la1-SN, causing changes of its subcellular localization. LA1 is required to regulate the expression of auxin transporters and signaling factors that control shoot gravitropism and tiller angle. High-throughput mRNA sequencing is performed to elucidate the molecular and cellular functions of LA1. The results show that LA1 may be involved in the nucleosome and chromatin assembly, and protein-DNA interactions to control gene expression, shoot gravitropism, and tiller angle. Our results provide new insight into the mechanisms whereby LA1 controls shoot gravitropism and tiller angle in rice.
PMID: 33067639
Ann Bot , IF:4.005 , 2020 Oct , V126 (5) : P807-824 doi: 10.1093/aob/mcaa121
Associations between phytohormones and cellulose biosynthesis in land plants.
School of Biosciences, University of Melbourne, Parkville, Victoria, Australia.; Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada, USA.; Department of Chemistry, University of Nevada, Reno, Nevada, USA.
BACKGROUND: Phytohormones are small molecules that regulate virtually every aspect of plant growth and development, from basic cellular processes, such as cell expansion and division, to whole plant environmental responses. While the phytohormone levels and distribution thus tell the plant how to adjust itself, the corresponding growth alterations are actuated by cell wall modification/synthesis and internal turgor. Plant cell walls are complex polysaccharide-rich extracellular matrixes that surround all plant cells. Among the cell wall components, cellulose is typically the major polysaccharide, and is the load-bearing structure of the walls. Hence, the cell wall distribution of cellulose, which is synthesized by large Cellulose Synthase protein complexes at the cell surface, directs plant growth. SCOPE: Here, we review the relationships between key phytohormone classes and cellulose deposition in plant systems. We present the core signalling pathways associated with each phytohormone and discuss the current understanding of how these signalling pathways impact cellulose biosynthesis with a particular focus on transcriptional and post-translational regulation. Because cortical microtubules underlying the plasma membrane significantly impact the trajectories of Cellulose Synthase Complexes, we also discuss the current understanding of how phytohormone signalling impacts the cortical microtubule array. CONCLUSION: Given the importance of cellulose deposition and phytohormone signalling in plant growth and development, one would expect that there is substantial cross-talk between these processes; however, mechanisms for many of these relationships remain unclear and should be considered as the target of future studies.
PMID: 32619216
Sci Rep , IF:3.998 , 2020 Oct , V10 (1) : P18089 doi: 10.1038/s41598-020-72586-3
Genetic control of tracheid properties in Norway spruce wood.
Department of Forest Genetics and Plant Physiology, Umea Plant Science Centre, Swedish University of Agricultural Science, Umea, Sweden.; RISE Bioeconomy, Box 5604, 114 86, Stockholm, Sweden.; Skogforsk, Ekebo 2250, 268 90, Svalov, Sweden.; IIC, Rosenlundsgatan 48B, 11863, Stockholm, Sweden.; Department of Forest Genetics and Plant Physiology, Umea Plant Science Centre, Swedish University of Agricultural Science, Umea, Sweden. m.rosario.garcia@slu.se.
Through the use of genome-wide association studies (GWAS) mapping it is possible to establish the genetic basis of phenotypic trait variation. Our GWAS study presents the first such effort in Norway spruce (Picea abies (L). Karst.) for the traits related to wood tracheid characteristics. The study employed an exome capture genotyping approach that generated 178 101 Single Nucleotide Polymorphisms (SNPs) from 40 018 probes within a population of 517 Norway spruce mother trees. We applied a least absolute shrinkage and selection operator (LASSO) based association mapping method using a functional multi-locus mapping approach, with a stability selection probability method as the hypothesis testing approach to determine significant Quantitative Trait Loci (QTLs). The analysis has provided 30 significant associations, the majority of which show specific expression in wood-forming tissues or high ubiquitous expression, potentially controlling tracheids dimensions, their cell wall thickness and microfibril angle. Among the most promising candidates based on our results and prior information for other species are: Picea abies BIG GRAIN 2 (PabBG2) with a predicted function in auxin transport and sensitivity, and MA_373300g0010 encoding a protein similar to wall-associated receptor kinases, which were both associated with cell wall thickness. The results demonstrate feasibility of GWAS to identify novel candidate genes controlling industrially-relevant tracheid traits in Norway spruce.
PMID: 33093525
Sci Rep , IF:3.998 , 2020 Oct , V10 (1) : P17196 doi: 10.1038/s41598-020-74144-3
Petal abscission in fragrant roses is associated with large scale differential regulation of the abscission zone transcriptome.
Molecular Biology and Biotechnology, CSIR-National Botanical Research Institute, Lucknow, 226001, India. priya.willis@gmail.com.; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India. priya.willis@gmail.com.; Bioinformatics Centre, Savitribai Phule Pune University, Pune, 411007, India.; High Performance Computing-Medical and Bioinformatics Applications Group, Centre for Development of Advanced Computing, Pune, 411008, India.; Molecular Biology and Biotechnology, CSIR-National Botanical Research Institute, Lucknow, 226001, India.; National Institute for Plant Genome Research, New Delhi, 110067, India.; National Centre for Natural Products Research, School of Pharmacy, University of Mississippi, Oxford, MS, 38677, USA.; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.; Molecular Biology and Biotechnology, CSIR-National Botanical Research Institute, Lucknow, 226001, India. ap.sane@nbri.res.in.; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India. ap.sane@nbri.res.in.
Flowers of fragrant roses such as Rosa bourboniana are ethylene-sensitive and undergo rapid petal abscission while hybrid roses show reduced ethylene sensitivity and delayed abscission. To understand the molecular mechanism underlying these differences, a comparative transcriptome of petal abscission zones (AZ) of 0 h and 8 h ethylene-treated flowers from R. bourboniana was performed. Differential regulation of 3700 genes (1518 up, 2182 down) representing 8.5% of the AZ transcriptome was observed between 0 and 8 h ethylene-treated R. bourboniana petal AZ. Abscission was associated with large scale up-regulation of the ethylene pathway but prominent suppression of the JA, auxin and light-regulated pathways. Regulatory genes encoding kinases/phosphatases/F-box proteins and transcription factors formed the major group undergoing differential regulation besides genes for transporters, wall modification, defense and phenylpropanoid pathways. Further comparisons with ethylene-treated petals of R. bourboniana and 8 h ethylene-treated AZ (R. hybrida) identified a core set of 255 genes uniquely regulated by ethylene in R. bourboniana AZ. Almost 23% of these encoded regulatory proteins largely conserved with Arabidopsis AZ components. Most of these were up-regulated while an entire set of photosystem genes was prominently down-regulated. The studies provide important information on regulation of petal abscission in roses.
PMID: 33057097
Plant Cell Rep , IF:3.825 , 2020 Oct doi: 10.1007/s00299-020-02618-9
Dynamic cytokinin signaling and function of auxin in cytokinin responsive domains during rice crown root development.
Department of Biotechnology, Indian Institute of Technology, Roorkee, Roorkee, Uttarakhand, 247667, India.; Department of Biotechnology, Indian Institute of Technology, Roorkee, Roorkee, Uttarakhand, 247667, India. shri.yadav@bt.iitr.ac.in.
KEY MESSAGE: We reveal the onset and dynamic tissue-specific cytokinin signaling domains and functional importance of auxin in the auxin-cytokinin interaction domains in shaping root architecture in the economically important rice plant. Plant hormones such as auxin and cytokinin are central regulators of root organogenesis. Typical in the grass species, the root system in rice is primarily composed of post-embryonic adventitious/crown roots (ARs/CRs). Antagonistic auxin-cytokinin activities mutually balance each other to ensure proper root development. Cytokinin has been shown to inhibit crown root initiation in rice; albeit, the responsive domains remain elusive during the initiation and outgrowth of crown root primordia (CRP). Here, we show the cytokinin response domains during various stages of CRP development. RNA-RNA in situ hybridization and protein immunohistochemistry studies of the reporter gene expressed under the cytokinin responsive synthetic promoter revealed detailed spatio-temporal cytokinin signaling domains in the developing CRP. Furthermore, rice lines genetically depleted for endogenous auxin in the cytokinin responsive domains provided insight into the functional importance of auxin signaling during crown root development. Thus, our study demonstrates the onset and dynamic tissue-specific cytokinin response and functional significance of auxin-cytokinin interaction during root architecture formation in rice, a model grass species.
PMID: 33047229
Plant Cell Rep , IF:3.825 , 2020 Oct doi: 10.1007/s00299-020-02612-1
Cytokinins as central regulators during plant growth and stress response.
Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, 250014, Shandong, China.; State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, Shandong, China.; Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, 250014, Shandong, China. suina@sdnu.edu.cn.
KEY MESSAGE: Cytokinins are a class of phytohormone that participate in the regulation of the plant growth, development, and stress response. In this review, the potential regulating mechanism during plant growth and stress response are discussed. Cytokinins are a class of phytohormone that participate in the regulation of plant growth, physiological activities, and yield. Cytokinins also play a key role in response to abiotic stresses, such as drought, salt and high or low temperature. Through the signal transduction pathway, cytokinins interact with various transcription factors via a series of phosphorylation cascades to regulate cytokinin-target gene expression. In this review, we systematically summarize the biosynthesis and metabolism of cytokinins, cytokinin signaling, and associated gene regulation, and highlight the function of cytokinins during plant development and resistance to abiotic stress. We also focus on the importance of crosstalk between cytokinins and other classes of phytohormones, including auxin, ethylene, strigolactone, and gibberellin. Our aim is to provide a comprehensive overview of recent findings on the mechanisms by which cytokinins act as central regulators of plant development and stress reactions, and highlight topics for future research.
PMID: 33025178
Plant Physiol Biochem , IF:3.72 , 2020 Oct , V157 : P70-78 doi: 10.1016/j.plaphy.2020.10.013
Effects of plant density on tillering in the weed grass Aegilops tauschii Coss. and its phytohormonal regulation.
Key Laboratory of Weed Biology and Management, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No.2 Yuanmingyuanxilu, Beijing, 100193, People's Republic of China.; Hebei Normal University of Science and Technology, Hebei Street No.360, Qinhuangdao, Hebei, 066004, People's Republic of China.; Key Laboratory of Weed Biology and Management, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No.2 Yuanmingyuanxilu, Beijing, 100193, People's Republic of China. Electronic address: xjli@ippcaas.cn.
Aegilops tauschii Coss, a notorious wheat field weed, poses a serious threat to wheat in China. Tillers are an important agronomic tool for yield. In this study, a total of 12 Ae. tauschii populations were collected from China to investigate the effect of plant density on tiller occurrence and its phytohormonal regulation. We assayed the growth parameters of Ae. tauschii and the levels of endogenous hormones at different plant densities. The results showed that plant density had a significant effect on the quantity and quality of Ae. tauschii seeds produced per plant. In particular, the tiller and spike numbers per plant were negatively affected by plant density (P < 0.0001). The contents of 13 endogenous hormones in the tiller nodes changed in response to plant density. Among them, indole-3-acetic acid (IAA) and gibberellin (GA) positively responded to plant density. However, the reverse result was found for cytokinin (CTK). Interestingly, phylogenetic tree analysis of auxin (AeYUCCA), CK (AeIPT) and GA (AeCPS) biosynthesis related genes found that phylogenies in the Gramineae for the three different genes were various, hinting at horizontal gene transfer. Moreover, the dynamics of the expression of AeYUCCA, AeIPT and AeCPS were roughly consistent with their phytohormone contents during tillering stage. When externally sprayed on plants of Ae. tauschii, 2,4-D isooctyl ester and GA3 markedly reduced its tillering while 6-BA had no significant effect.
PMID: 33091798
Mol Plant Microbe Interact , IF:3.696 , 2020 Oct : PMPMI08200211R doi: 10.1094/MPMI-08-20-0211-R
Validamycin A Induces Broad-Spectrum Resistance Involving Salicylic Acid and Jasmonic Acid/Ethylene Signaling Pathways.
College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Validamycin A (VMA) is an aminoglycoside antibiotic used to control rice sheath blight. Although it has been reported that VMA can induce the plant defense responses, the mechanism remains poorly understood. Here, we found that reactive oxygen species (ROS) bursts and callose deposition in Arabidopsis thaliana, rice (Oryza sativa L.), and wheat (Triticum aestivum L.) were induced by VMA and were most intense with 10 mug of VMA per milliliter at 24 h. Moreover, we showed that VMA induced resistance against Pseudomonas syringae, Botrytis cinerea, and Fusarium graminearum in Arabidopsis leaves, indicating that VMA induces broad-spectrum disease resistance in both dicots and monocots. In addition, VMA-mediated resistance against P. syringae was not induced in NahG transgenic plants, was partially decreased in npr1 mutants, and VMA-mediated resistance to B. cinerea was not induced in npr1, jar1, and ein2 mutants. These results strongly indicated that VMA triggers plant defense responses to both biotrophic and necrotrophic pathogens involved in salicylic acid (SA) and jasmonic acid/ethylene (JA/ET) signaling pathways and is dependent on NPR1. In addition, transcriptome analysis further revealed that VMA regulated the expression of genes involved in SA, JA/ET, abscisic acid (ABA), and auxin signal pathways. Taken together, VMA induces systemic resistance involving in SA and JA/ET signaling pathways and also exerts a positive influence on ABA and auxin signaling pathways. Our study highlights the creative application of VMA in triggering plant defense responses against plant pathogens, providing a valuable insight into applying VMA to enhance plant resistance and reduce the use of chemical pesticides.[Formula: see text] Copyright (c) 2020 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
PMID: 32815479
BMC Genomics , IF:3.594 , 2020 Oct , V21 (1) : P728 doi: 10.1186/s12864-020-07110-y
Comprehensive transcriptomic analysis provides new insights into the mechanism of ray floret morphogenesis in chrysanthemum.
Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Education Ministry, School of Landscape Architecture, Beijing Forestry University, Beijing, 100083, China.; Fuzhou Planning Design & Research Institute, Fuzhou, 350108, China.; Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Education Ministry, School of Landscape Architecture, Beijing Forestry University, Beijing, 100083, China. silandai@sina.com.
BACKGROUND: The ray floret shapes referred to as petal types on the chrysanthemum (Chrysanthemum x morifolium Ramat.) capitulum is extremely abundant, which is one of the most important ornamental traits of chrysanthemum. However, the regulatory mechanisms of different ray floret shapes are still unknown. C. vestitum is a major origin species of cultivated chrysanthemum and has flat, spoon, and tubular type of ray florets which are the three basic petal types of chrysanthemum. Therefore, it is an ideal model material for studying ray floret morphogenesis in chrysanthemum. Here, using morphological, gene expression and transcriptomic analyses of different ray floret types of C. vestitum, we explored the developmental processes and underlying regulatory networks of ray florets. RESULTS: The formation of the flat type was due to stagnation of its dorsal petal primordium, while the petal primordium of the tubular type had an intact ring shape. Morphological differences between the two ray floret types occurred during the initial stage with vigorous cell division. Analysis of genes related to flower development showed that CYCLOIDEA genes, including CYC2b, CYC2d, CYC2e, and CYC2f, were differentially expressed in different ray floret types, while the transcriptional levels of others, such as MADS-box genes, were not significantly different. Hormone-related genes, including SMALL AUXIN UPREGULATED RNA (SAUR), GRETCHEN HAGEN3 (GH3), GIBBERELLIN 2-BETA-DIOXYGENASE 1 (GA2OX1) and APETALA2/ETHYLENE RESPONSIVE FACTOR (AP2/ERF), were identified from 1532 differentially expressed genes (DEGs) in pairwise comparisons among the flat, spoon, and tubular types, with significantly higher expression in the tubular type than that in the flat type and potential involvement in the morphogenesis of different ray floret types. CONCLUSIONS: Our findings, together with the gene interactional relationships reported for Arabidopsis thaliana, suggest that hormone-related genes are highly expressed in the tubular type, promoting petal cell division and leading to the formation of a complete ring of the petal primordium. These results provide novel insights into the morphological variation of ray floret of chrysanthemum.
PMID: 33081692
BMC Genomics , IF:3.594 , 2020 Oct , V21 (1) : P694 doi: 10.1186/s12864-020-07116-6
pH-dependent transcriptional profile changes in iron-deficient Arabidopsis roots.
Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan.; Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan. wosh@gate.sinica.edu.tw.; Biotechnology Center, National Chung-Hsing University, Taichung, 40227, Taiwan. wosh@gate.sinica.edu.tw.; Genome and Systems Biology Degree Program, College of Life Science, National Taiwan University, Taipei, 10617, Taiwan. wosh@gate.sinica.edu.tw.
BACKGROUND: Iron is an essential element for plants and abundantly present in most mineral soils. The mobility of iron is, however, dependent on the redox potential and hydrogen activity (pH) of the soil, factors that may limit its availability to plants in particular at alkaline pHs. Iron deficiency triggers pronounced changes in the transcriptional profile of plants, inducing processes that aid in the acquisition, uptake, and translocation of iron. How ambient pH impact the transcriptional iron deficiency response has not yet been elucidated in detail. RESULTS: Here, we provide an RNA-seq data set that catalogs global gene expression changes of iron-deficient plants grown at either optimal (5.5) or high (7.0) pH. A suite of 857 genes changed significantly and more than twofold in expression; only 54 genes of this suite were also differentially expressed between iron-deficient and iron-sufficient plants grown at pH 5.5. Among the high pH-responsive genes, 186 were earlier shown to be responsive to short-term transfer to low pH, 91 genes of this subset were anti-directionally regulated by high and low pH. The latter subset contained genes involved in cell wall organization, auxin homeostasis, and potential hubs of yet undefined signaling circuits. Growing iron-deficient plants at high pH also modulated the transcriptional iron deficiency response observed at pH 5.5 by compromising the enzymatic reduction of ferric chelates and favoring the production of iron-mobilizing coumarins. CONCLUSIONS: It is concluded that ambient pH is an important determinant of global gene expression which tunes iron acquisition to the prevailing edaphic conditions.
PMID: 33023472
BMC Genomics , IF:3.594 , 2020 Oct , V21 (1) : P696 doi: 10.1186/s12864-020-07103-x
Genome-wide small RNA profiling reveals tiller development in tall fescue (Festuca arundinacea Schreb).
CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Wuhan, 430074, China. hut420@wbgcas.cn.; Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, 430074, China. hut420@wbgcas.cn.; College of Agriculture, Henan University of Science and Technology, Luoyang, China.; CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Wuhan, 430074, China.; Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, 430074, China.; University of Chinese Academy of Sciences, Beijing, 100049, China.; CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Wuhan, 430074, China. chenliang888@wbgcas.cn.; Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, 430074, China. chenliang888@wbgcas.cn.
BACKGROUND: Tall fescue (Festuca arundinacea Schreb.) is a major cool-season forage and turfgrass species. The low tiller density and size dramatically limits its turf performance and forage yield. MicroRNAs (miRNA)-genes modules play critical roles in tiller development in plants. In this study, a genome-wide small RNA profiling was carried out in two tall fescue genotypes contrasting for tillering production ('Ch-3', high tiller production rate and 'Ch-5', low tiller production rate) and two types of tissue samples at different tillering development stage (Pre-tillering, grass before tillering; Tillering, grass after tillering). 'Ch-3', 'Ch-5', Pre-tillering, and Tillering samples were analyzed using high-throughput RNA sequencing. RESULTS: A total of 222 million high-quality clean reads were generated and 208 miRNAs were discovered, including 148 known miRNAs belonging to 70 families and 60 novel ones. Furthermore, 18 miRNAs were involved in tall fescue tiller development process. Among them, 14 miRNAs displayed increased abundance in both Ch-3 and Tillering plants compared with that in Ch-5 and Pre-tillering plants and were positive with tillering, while another four miRNAs were negative with tiller development. Out of the three miRNAs osa-miR156a, zma-miR528a-3p and osa-miR444b.2, the rest of 15 miRNAs were newfound and associated with tiller development in plants. Based on our previous full-length transcriptome analysis in tall fescue, 28,927 potential target genes were discovered for all identified miRNAs. Most of the 212 target genes of the 18 miRNAs were dominantly enriched into "ubiquitin-mediated proteolysis", "phagosome", "fatty acid biosynthesis", "oxidative phosphorylation", and "biosynthesis of unsaturated fatty acids" KEGG pathways. In addition, bdi-miR167e-3p targets two kinase proteins EIF2AK4 and IRAK4, and osa-miR397a targets auxin response factor 5, which may be the significant miRNA-genes controllers in tillering development. CONCLUSIONS: This is the first genome-wide miRNA profiles analysis to identify regulators involved in tiller development in cool-season turfgrass. Tillering related 18 miRNAs and their 212 target genes provide novel information for the understanding of the molecular mechanisms of miRNA-genes mediated tiller development in cool-season turfgrass.
PMID: 33023464
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
BMC Plant Biol , IF:3.497 , 2020 Oct , V20 (1) : P490 doi: 10.1186/s12870-020-02676-x
Genome-wide association studies and whole-genome prediction reveal the genetic architecture of KRN in maize.
Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.; Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China. liyu03@caas.cn.; Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China. wangtianyu@caas.cn.
BACKGROUND: Kernel row number (KRN) is an important trait for the domestication and improvement of maize. Exploring the genetic basis of KRN has great research significance and can provide valuable information for molecular assisted selection. RESULTS: In this study, one single-locus method (MLM) and six multilocus methods (mrMLM, FASTmrMLM, FASTmrEMMA, pLARmEB, pKWmEB and ISIS EM-BLASSO) of genome-wide association studies (GWASs) were used to identify significant quantitative trait nucleotides (QTNs) for KRN in an association panel including 639 maize inbred lines that were genotyped by the MaizeSNP50 BeadChip. In three phenotyping environments and with best linear unbiased prediction (BLUP) values, the seven GWAS methods revealed different numbers of KRN-associated QTNs, ranging from 11 to 177. Based on these results, seven important regions for KRN located on chromosomes 1, 2, 3, 5, 9, and 10 were identified by at least three methods and in at least two environments. Moreover, 49 genes from the seven regions were expressed in different maize tissues. Among the 49 genes, ARF29 (Zm00001d026540, encoding auxin response factor 29) and CKO4 (Zm00001d043293, encoding cytokinin oxidase protein) were significantly related to KRN, based on expression analysis and candidate gene association mapping. Whole-genome prediction (WGP) of KRN was also performed, and we found that the KRN-associated tagSNPs achieved a high prediction accuracy. The best strategy was to integrate all of the KRN-associated tagSNPs identified by all GWAS models. CONCLUSIONS: These results aid in our understanding of the genetic architecture of KRN and provide useful information for genomic selection for KRN in maize breeding.
PMID: 33109077
BMC Plant Biol , IF:3.497 , 2020 Oct , V20 (1) : P482 doi: 10.1186/s12870-020-02698-5
Variation in the expression of a transmembrane protein influences cell growth in Arabidopsis thaliana petals by altering auxin responses.
Cell and Developmental Biology Department John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.; Cell and Developmental Biology Department John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK. michael.bevan@jic.ac.uk.
BACKGROUND: The same species of plant can exhibit very diverse sizes and shapes of organs that are genetically determined. Characterising genetic variation underlying this morphological diversity is an important objective in evolutionary studies and it also helps identify the functions of genes influencing plant growth and development. Extensive screens of mutagenised Arabidopsis populations have identified multiple genes and mechanisms affecting organ size and shape, but relatively few studies have exploited the rich diversity of natural populations to identify genes involved in growth control. RESULTS: We screened a relatively well characterised collection of Arabidopsis thaliana accessions for variation in petal size. Association analyses identified sequence and gene expression variation on chromosome 4 that made a substantial contribution to differences in petal area. Variation in the expression of a previously uncharacterised gene At4g16850 (named as KSK) had a substantial role on variation in organ size by influencing cell size. Over-expression of KSK led to larger petals with larger cells and promoted the formation of stamenoid features. The expression of auxin-responsive genes known to limit cell growth was reduced in response to KSK over-expression. ANT expression was also reduced in KSK over-expression lines, consistent with altered floral identities. Auxin responses were reduced in KSK over-expressing cells, consistent with changes in auxin-responsive gene expression. KSK may therefore influence auxin responses during petal development. CONCLUSIONS: Understanding how genetic variation influences plant growth is important for both evolutionary and mechanistic studies. We used natural populations of Arabidopsis thaliana to identify sequence variation in a promoter region of Arabidopsis accessions that mediated differences in the expression of a previously uncharacterised membrane protein. This variation contributed to altered auxin responses and cell size during petal growth.
PMID: 33092536
BMC Plant Biol , IF:3.497 , 2020 Oct , V20 (1) : P453 doi: 10.1186/s12870-020-02659-y
Database: web application for visualization of the cumulated RNAseq data against the salicylic acid (SA) and methyl jasmonate (MeJA) treatment of Arabidopsis thaliana.
Division of Bio & Medical Big data department (BK4 Program) at Gyeongsang National University, Jinju, Republic of Korea.; Division of Bio & Medical Big data department (BK4 Program) at Gyeongsang National University, Jinju, Republic of Korea. kangyangjae@gnu.ac.kr.; Division of Life Science Department at Gyeongsang National University, Jinju, Republic of Korea. kangyangjae@gnu.ac.kr.
BACKGROUND: Plants have adapted to survive under adverse conditions or exploit favorable conditions in response to their environment as sessile creatures. In a way of plant adaptation, plant hormones have been evolved to efficiently use limited resources. Plant hormones including auxin, jasmonic acid, salicylic acid, and ethylene have been studied to reveal their role in plant adaptation against their environment by phenotypic observation with experimental design such as mutation on hormone receptors and treatment / non-treatment of plant hormones along with other environmental conditions. With the development of Next Generation Sequencing (NGS) technology, it became possible to score the total gene expression of the sampled plants and estimate the degree of effect of plant hormones in gene expression. This allowed us to infer the signaling pathway through plant hormones, which greatly stimulated the study of functional genomics using mutants. Due to the continued development of NGS technology and analytical techniques, many plant hormone-related studies have produced and accumulated NGS-based data, especially RNAseq data have been stored in the sequence read archive represented by NCBI, EBI, and DDBJ. DESCRIPTION: Here, hormone treatment RNAseq data of Arabidopsis (Col0), wild-type genotype, were collected with mock, SA, and MeJA treatments. The genes affected by hormones were identified through a machine learning approach. The degree of expression of the affected gene was quantified, visualized in boxplot using d3 (data-driven-document), and the database was built by Django. CONCLUSION: Using this database, we created a web application ( http://pgl.gnu.ac.kr/hormoneDB/ ) that lists hormone-related or hormone-affected genes and visualizes the boxplot of the gene expression of selected genes. This web application eventually aids the functional genomics researchers who want to gather the cases of the gene responses by the hormones.
PMID: 33008298
Planta , IF:3.39 , 2020 Oct , V252 (5) : P78 doi: 10.1007/s00425-020-03486-z
WDR5a functions in cadmium-inhibited root meristem growth by regulating nitric oxide accumulation in Arabidopsis.
State Key Laboratory of Cotton Biology, State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China.; Nanyang Vocational College of Agriculture, Nanyang, 473000, China.; Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, Jiangsu Ocean University, Lianyungang, 222005, China.; State Key Laboratory of Cotton Biology, State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China. liuwencheng@henu.edu.cn.
MAIN CONCLUSION: Cadmium stress induces WDR5a expression to promote NO accumulation to repress root meristem growth via suppressing auxin transport and synthesis in Arabidopsis. Nitric oxide (NO) synthase (NOS)-like activity plays a vital role in toxic cadmium (Cd)-induced NO production and inhibition of root meristem growth, while factor(s) regulating NOS-like activity and root meristem growth in plant response to Cd has not been identified yet. Here, we report that WD40 repeat 5a (WDR5a) functions in Cd-induced NOS-like activity, NO accumulation and root meristem growth suppression. We found that wdr5a-1 mutant root has increased root meristem growth with lower NOS-like activity and NO accumulation than wild type upon Cd exposure, and exogenous NO donors sodium nitroprusside or nitrosoglutathione can restore its reduced Cd sensitivity. In addition, Cd activates WDR5a expression in roots, and overexpressing WDR5a results in increased NO accumulation and suppressed root meristem growth similar to Cd-stressed wild-type roots, while scavenging NO or inhibiting NOS-like activity significantly reverts these effects of Cd. Furthermore, WDR5a acts in Cd-repressed auxin accumulation through reducing the levels of auxin efflux carriers PIN1/3/7 and biosynthetic enzyme TAA1, and reduced sensitivity of wdr5a-1 root meristem to Cd can be partially reverted by inhibiting TAA1 activity pharmaceutically or mutating TAA1 genetically. This study identified WDR5a as a key factor modulating NO accumulation and root meristem growth in plant response to Cd.
PMID: 33033954
Planta , IF:3.39 , 2020 Oct , V252 (5) : P75 doi: 10.1007/s00425-020-03467-2
Salicylic acid regulates adventitious root formation via competitive inhibition of the auxin conjugation enzyme CsGH3.5 in cucumber hypocotyls.
Ministry of Agriculture, Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China. dongchunjuan@caas.cn.; Ministry of Agriculture, Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China.; Ministry of Agriculture, Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China. shangqingmao@caas.cn.
MAIN CONCLUSION: Exogenous SA treatment at appropriate concentrations promotes adventitious root formation in cucumber hypocotyls, via competitive inhibiting the IAA-Asp synthetase activity of CsGH3.5, and increasing the local free IAA level. Adventitious root formation is critical for the cutting propagation of horticultural plants. Indole-3-acetic acid (IAA) has been shown to play a central role in regulating this process, while for salicylic acid (SA), its exact effects and regulatory mechanism have not been elucidated. In this study, we showed that exogenous SA treatment at the concentrations of both 50 and 100 microM promoted adventitious root formation at the base of the hypocotyl of cucumber seedlings. At these concentrations, SA could induce the expression of CYCLIN and Cyclin-dependent Kinase (CDK) genes during adventitious rooting. IAA was shown to be involved in SA-induced adventitious root formation in cucumber hypocotyls. Exposure to exogenous SA led to a slight increase in the free IAA content, and pre-treatment with the auxin transport inhibitor 1-naphthylphthalamic acid (NPA) almost completely abolished the inducible effects of SA on adventitious root number. SA-induced IAA accumulation was also associated with the enhanced expression of Gretchen Hagen3.5 (CsGH3.5). The in vitro enzymatic assay indicated that CsGH3.5 has both IAA- and SA-amido synthetase activity and prefers aspartate (Asp) as the amino acid conjugate. The Asp concentration dictated the functional activity of CsGH3.5 on IAA. Both affinity and catalytic efficiency (Kcat/Km) increased when the Asp concentration increased from 0.3 to 1 mM. In contrast, CsGH3.5 showed equal catalytic efficiency for SA at low and high Asp concentrations. Furthermore, SA functioned as a competitive inhibitor of the IAA-Asp synthetase activity of CsGH3.5. During adventitious formation, SA application indeed repressed the IAA-Asp levels in the rooting zone. These data show that SA plays an inducible role in adventitious root formation in cucumber through competitive inhibition of the auxin conjugation enzyme CsGH3.5. SA reduces the IAA conjugate levels, thereby increasing the local free IAA level and ultimately enhancing adventitious root formation.
PMID: 33026530
Plant Mol Biol , IF:3.302 , 2020 Oct doi: 10.1007/s11103-020-01086-9
Bulk RNA-Seq analysis to dissect the regulation of stigma position in tomato.
Department of Agriculture and Forest Sciences, University of Tuscia, Via S.C. de Lellis snc, 01100, Viterbo, Italy.; Department of Agriculture and Forest Sciences, University of Tuscia, Via S.C. de Lellis snc, 01100, Viterbo, Italy. mazz@unitus.it.
KEY MESSAGE: Transcriptomic analysis of tomato genotypes contrasting for stigma position suggests that stigma insertion occurred by the disruption of a process that finds a parallel in Arabidopsis gynoecium development. Domestication of cultivated tomato (Solanum lycopersicum L.) included the transition from allogamy to autogamy that occurred through the loss of self-incompatibilty and the retraction of the stigma within the antheridial cone. Although the inserted stigma is an established phenotype in modern tomatoes, an exserted stigma is still present in several landraces or vintage varieties. Moreover, exsertion of the stigma is a frequent response to high temperature stress and, being a cause of reduced fertility, a trait of increasing importance. Few QTLs for stigma position have been described and only one of the underlying genes identified. To gain insights on genes involved in stigma position in tomato, a bulk RNA sequencing (RNA-Seq) approach was adopted, using two groups of contrasting genotypes. Phenotypic analysis confirmed the extent and the stability of stigma position in the selected genotypes, whereas they were highly heterogeneous for other reproductive and productive traits. The RNA-Seq analysis yielded 801 differentially expressed genes (DEGs), 566 up-regulated and 235 down-regulated in the genotypes with exserted stigma. Validation by quantitative PCR indicated a high reliability of the RNA-Seq data. Up-regulated DEGs were enriched for genes involved in the cell wall metabolism, lipid transport, auxin response and flavonoid biosynthesis. Down-regulated DEGs were enriched for genes involved in translation. Validation of selected genes on pistil tissue of the 26 single genotypes revealed that differences between bulks could both be due to a general trend of the bulk or to the behaviour of single genotypes. Novel candidate genes potentially involved in the control of stigma position in tomato are discussed.
PMID: 33104942
Phytopathology , IF:3.234 , 2020 Oct : PPHYTO02200046R doi: 10.1094/PHYTO-02-20-0046-R
Auxin Profiling and GmPIN Expression in Phytophthora sojae-Soybean Root Interactions.
Department of Plant Pathology, The Ohio State University, Wooster, OH 44691.; Center for Soybean Research, The Ohio State University, Wooster, OH 44691.; Department of Horticulture and Crop Science and OARDC Metabolite Analysis Cluster, The Ohio State University, Wooster, OH 44691.; Center for Applied Plant Sciences, The Ohio State University, Columbus, OH 43210.
Auxin (indole-3-acetic acid, IAA) has been implicated as a susceptibility factor in both beneficial and pathogenic molecular plant-microbe interactions. Previous studies have identified a large number of auxin-related genes underlying quantitative disease resistance loci (QDRLs) for Phytophthora sojae. Thus, we hypothesized that auxin may be involved the P. sojae-soybean interaction. The levels of IAA and related metabolites were measured in mycelia and media supernatant as well as in mock and inoculated soybean roots in a time course assay. The expression of 11 soybean Pin-formed (GmPIN) auxin efflux transporter genes was also examined. Tryptophan, an auxin precursor, was detected in the P. sojae mycelia and media supernatant. During colonization of roots, levels of IAA and related metabolites were significantly higher in both moderately resistant Conrad and moderately susceptible Sloan inoculated roots compared with mock controls at 48 h postinoculation (hpi) in one experiment and at 72 hpi in a second, with Sloan accumulating higher levels of the auxin catabolite IAA-Ala than Conrad. Additionally, one GmPIN at 24 hpi, one at 48 hpi, and three at 72 hpi had higher expression in inoculated compared with the mock control roots in Conrad. The ability of resistant cultivars to cope with auxin accumulation may play an important role in quantitative disease resistance. Levels of jasmonic acid (JA), another plant hormone associated with defense responses, were also higher in inoculated roots at these same time points, suggesting that JA also plays a role during the later stages of infection.
PMID: 32602813
Gene , IF:2.984 , 2020 Oct , V758 : P144942 doi: 10.1016/j.gene.2020.144942
Transcription factor LkWOX4 is involved in adventitious root development in Larix kaempferi.
State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China; College of Bioengineering and Biotechnology, Tianshui Normal University, Gansu 741000, China.; State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China.; Department of Horticultural Science, North Carolina State University, Raleigh 27695, USA.; State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China. Electronic address: larch_rif@163.com.
WUSCHEL-related homeobox4 (WOX4) plays important roles in vascular formation and adventitious root (AR) development. Here, we cloned the WOX4 from the AR of Larix kaempferi, whose cDNA is 1452 bp in length and encodes 483 amino acids. LkWOX4 is mainly expressed in the layer formation area of the stem at 10 days after cutting and its expression levels in the middles and ends of the ARs were higher than that in the AR tips. The fused protein LkWOX4-GFP localized in the nucleus. The heterologous overexpression of LkWOX4 in 84 K poplar significantly increased AR numbers and decreased AR lengths. In LkWOX4 plants, the endogenous jasmonic acid and abscisic acid contents significantly decreased in stems, while the auxin, jasmonic acid and abscisic acid contents significantly increased in ARs. RNA-Seq of those LkWOX4 overexpression poplar plants showed that the expression of plant hormone signaling genes (ARF2, ARF3, ARF7 and ARF18), rooting-related transcription factors (WOX5, LBD29 and SCR) and root development-related genes (CYCD3, GRF1 and TAA1) were affected. Moreover, we found that LkWOX4 interacts with LkPAT18, LkACBP6, and LkCIP7 using yeast two hybrid screening. Thus, we found LkWOX4 involves in the AR initiation and development, which might be regulated through the IAA, JA and ABA signaling pathways.
PMID: 32640309
Plants (Basel) , IF:2.762 , 2020 Oct , V9 (11) doi: 10.3390/plants9111406
Expression Analysis of Key Auxin Biosynthesis, Transport, and Metabolism Genes of Betula pendula with Special Emphasis on Figured Wood Formation in Karelian Birch.
Forest Research Institute, Karelian Research Centre of the Russian Academy of Sciences, 11 Pushkinskaya st., 185910 Petrozavodsk, Russia.
Auxin status in woody plants is believed to be a critical factor for the quantity and quality of the wood formed. It has been previously demonstrated that figured wood formation in Karelian birch (Betula pendula Roth var. carelica (Merckl.) Hamet-Ahti) is associated with a reduced auxin level and elevated sugar content in the differentiating xylem, but the molecular mechanisms of the abnormal xylogenesis remained largely unclear. We have identified genes involved in auxin biosynthesis (Yucca), polar auxin transport (PIN) and the conjugation of auxin with amino acids (GH3) and UDP-glucose (UGT84B1) in the B. pendula genome, and analysed their expression in trunk tissues of trees differing in wood structure. Almost all the investigated genes were overexpressed in Karelian birch trunks. Although Yucca genes were overexpressed, trunk tissues in areas developing figured grain had traits of an auxin-deficient phenotype. Overexpression of GH3s and UGT84B1 appears to have a greater effect on figured wood formation. Analysis of promoters of the differentially expressed genes revealed a large number of binding sites with various transcription factors associated with auxin and sugar signalling. These data agree with the hypothesis that anomalous figured wood formation in Karelian birch may be associated with the sugar induction of auxin conjugation.
PMID: 33105649
Plants (Basel) , IF:2.762 , 2020 Oct , V9 (10) doi: 10.3390/plants9101347
Phytotoxicity, Morphological, and Metabolic Effects of the Sesquiterpenoid Nerolidol on Arabidopsis thaliana Seedling Roots.
Department of Agriculture, Food and Environment, University of Pisa, 56126 Pisa, Italy.; Independent Researcher, Pine 211, Raintree Park Dwaraka Krishna, Namburu AP-522508, India.; Dipartimento di Biologia, Ecologia e Scienze della Terra (DiBEST), Universita della Calabria, 87040 Arcavacata di Rende, CS, Italy.; Department AGRARIA, University Mediterranea of Reggio Calabria Localita Feo di Vito, 89124 Reggio Calabria, RC, Italy.
Natural herbicides that are based on allelopathy of compounds, can offer effective alternatives to chemical herbicides towards sustainable agricultural practices. Nerolidol, a sesquiterpenoid alcohol synthesized by many plant families, was shown to be the most effective allelopathic compound in a preliminary screening performed with several other sesquiterpenoids. In the present study, Arabidopsis thaliana seedlings were treated for 14 d with various cis-nerolidol concentrations (0, 50, 100, 200, 400, and 800 microM) to investigate its effects on root growth and morphology. To probe the underlying changes in root metabolome, we conducted untargeted gas chromatography mass spectrometry (GC-MS) based metabolomics to find out the specificity or multi-target action of this sesquiterpenoid alcohol. Oxidative stress (measured as levels of H2O2 and malondialdehyde (MDA) by-product) and antioxidant enzyme activities, i.e., superoxide dismutase (SOD) and catalase (CAT) were also evaluated in the roots. Nerolidol showed an IC50 (120 microM), which can be considered low for natural products. Nerolidol caused alterations in root morphology, brought changes in auxin balance, induced changes in sugar, amino acid, and carboxylic acid profiles, and increased the levels of H2O2 and MDA in root tissues in a dose-dependent manner. Several metabolomic-scale changes induced by nerolidol support the multi-target action of nerolidol, which is a positive feature for a botanical herbicide. Though it warrants further mechanistic investigation, nerolidol is a promising compound for developing a new natural herbicide.
PMID: 33053766
Plants (Basel) , IF:2.762 , 2020 Oct , V9 (10) doi: 10.3390/plants9101335
Identification of Candidate Genes Involved in Fruit Ripening and Crispness Retention Through Transcriptome Analyses of a 'Honeycrisp' Population.
Department of Horticultural Science, University of Minnesota, Saint Paul, MN 55108, USA.
Crispness retention is a postharvest trait that fruit of the 'Honeycrisp' apple and some of its progeny possess. To investigate the molecular mechanisms of crispness retention, progeny individuals derived from a 'Honeycrisp' x MN1764 population with fruit that either retain crispness (named "Retain"), lose crispness (named "Lose"), or that are not crisp at harvest (named "Non-crisp") were selected for transcriptomic comparisons. Differentially expressed genes (DEGs) were identified using RNA-Seq, and the expression levels of the DEGs were validated using nCounter((R)). Functional annotation of the DEGs revealed distinct ripening behaviors between fruit of the "Retain" and "Non-crisp" individuals, characterized by opposing expression patterns of auxin- and ethylene-related genes. However, both types of genes were highly expressed in the fruit of "Lose" individuals and 'Honeycrisp', which led to the potential involvements of genes encoding auxin-conjugating enzyme (GH3), ubiquitin ligase (ETO), and jasmonate O-methyltransferase (JMT) in regulating fruit ripening. Cell wall-related genes also differentiated the phenotypic groups; greater numbers of cell wall synthesis genes were highly expressed in fruit of the "Retain" individuals and 'Honeycrisp' when compared with "Non-crisp" individuals and MN1764. On the other hand, the phenotypic differences between fruit of the "Retain" and "Lose" individuals could be attributed to the functioning of fewer cell wall-modifying genes. A cell wall-modifying gene, MdXTH, was consistently identified as differentially expressed in those fruit over two years in this study, so is a major candidate for crispness retention.
PMID: 33050481
Plants (Basel) , IF:2.762 , 2020 Oct , V9 (10) doi: 10.3390/plants9101311
Auxin Homeostasis and Distribution of the Auxin Efflux Carrier PIN2 Require Vacuolar NHX-Type Cation/H(+) Antiporter Activity.
Boyce Thompson Institute, Ithaca, NY 14850, USA.; Department of Plant Sciences, University of California, Davis, CA 95616, USA.; Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 1A1, Canada.; Horticultural Sciences Department, Tropical Research and Education Center, University of Florida, Homestead, FL, 33031, USA.
The Arabidopsis vacuolar Na(+)/H(+) transporters (NHXs) are important regulators of intracellular pH, Na(+) and K(+) homeostasis and necessary for normal plant growth, development, and stress acclimation. Arabidopsis contains four vacuolar NHX isoforms known as AtNHX1 to AtNHX4. The quadruple knockout nhx1nhx2nhx3nhx4, lacking any vacuolar NHX-type antiporter activity, displayed auxin-related phenotypes including loss of apical dominance, reduced root growth, impaired gravitropism and less sensitivity to exogenous IAA and NAA, but not to 2,4-D. In nhx1nhx2nhx3nhx4, the abundance of the auxin efflux carrier PIN2, but not PIN1, was drastically reduced at the plasma membrane and was concomitant with an increase in PIN2 labeled intracellular vesicles. Intracellular trafficking to the vacuole was also delayed in the mutant. Measurements of free IAA content and imaging of the auxin sensor DII-Venus, suggest that auxin accumulates in root tips of nhx1nhx2nhx3nhx4. Collectively, our results indicate that vacuolar NHX dependent cation/H(+) antiport activity is needed for proper auxin homeostasis, likely by affecting intracellular trafficking and distribution of the PIN2 efflux carrier.
PMID: 33023035
Protoplasma , IF:2.751 , 2020 Oct doi: 10.1007/s00709-020-01552-7
The nature of the interaction Azospirillum-Arabidopsis determine the molecular and morphological changes in root and plant growth promotion.
Instituto de Investigaciones Quimico Biologicas, Universidad Michoacana de San Nicolas de Hidalgo, Ciudad Universitaria, Edif. A1', 58040, Morelia, Michoacan, Mexico.; Instituto de Investigaciones Quimico Biologicas, Universidad Michoacana de San Nicolas de Hidalgo, Ciudad Universitaria, Edif. A1', 58040, Morelia, Michoacan, Mexico. egpineda@umich.mx.
Plant growth promoting rhizobacteria influence host functional and adaptive traits via complex mechanisms that are just started to be clarified. Azospirillum brasilense acts as a probiotic bacterium, but detailed information about its molecular mechanisms of phytostimulation is scarce. Three interaction systems were established to analyze the impact of A. brasilense Sp245 on the phenotype of Arabidopsis seedlings, and underlying molecular responses were assessed under the following growth conditions: (1) direct contact of roots with the bacterium, (2) chemical communication via diffusible compounds produced by the bacterium, (3) signaling via volatiles. A. brasilense Sp245 improved shoot and root biomass and lateral root production in the three interaction systems assayed. Cell division, quiescent center, and differentiation protein reporters pCYCB1;1::GUS, WOX5::GFP, and pAtEXP7::GUS had a variable expression in roots depending of the nature of interaction. pCYCB1;1::GUS and WOX5::GFP increased with volatile compounds, whereas pAtEXP7::GUS expression was enhanced towards the root tip in plants with direct contact with the bacterium. The auxin reporter DR5::GUS was highly expressed with diffusible and volatile compounds, and accordingly, auxin signaling mutants pin3, slr1, arf7arf19, and tir1afb2afb3 showed differential phytostimulant responses when compared with the wild type. By contrast, ethylene signaling was not determinant to mediate root changes in response to the different interactions, as observed using the ethylene-related mutants etr1, ein2, and ein3. Our data highlight the diverse effects by which A. brasilense Sp245 improves plant growth and root architectural traits and define a critical role of auxin but not ethylene in mediating root response to bacterization.
PMID: 33009649
PLoS One , IF:2.74 , 2020 , V15 (10) : Pe0240886 doi: 10.1371/journal.pone.0240886
Phytohormone production by the arbuscular mycorrhizal fungus Rhizophagus irregularis.
Laboratoire de Recherche en Sciences Vegetales, Universite de Toulouse, CNRS, UPS, Castanet-Tolosan, France.; MetaboHub-Metatoul AgromiX, Laboratoire de Recherche en Sciences Vegetales, Universite de Toulouse, CNRS, UPS, Castanet-Tolosan, France.; Genomique et Biotechnologie des Fruits, Universite de Toulouse, Toulouse INP, INRA, Castanet-Tolosan, France.
Arbuscular mycorrhizal symbiosis is a mutualistic interaction between most land plants and fungi of the glomeromycotina subphylum. The initiation, development and regulation of this symbiosis involve numerous signalling events between and within the symbiotic partners. Among other signals, phytohormones are known to play important roles at various stages of the interaction. During presymbiotic steps, plant roots exude strigolactones which stimulate fungal spore germination and hyphal branching, and promote the initiation of symbiosis. At later stages, different plant hormone classes can act as positive or negative regulators of the interaction. Although the fungus is known to reciprocally emit regulatory signals, its potential contribution to the phytohormonal pool has received little attention, and has so far only been addressed by indirect assays. In this study, using mass spectrometry, we analyzed phytohormones released into the medium by germinated spores of the arbuscular mycorrhizal fungus Rhizophagus irregularis. We detected the presence of a cytokinin (isopentenyl adenosine) and an auxin (indole-acetic acid). In addition, we identified a gibberellin (gibberellin A4) in spore extracts. We also used gas chromatography to show that R. irregularis produces ethylene from methionine and the alpha-keto gamma-methylthio butyric acid pathway. These results highlight the possibility for AM fungi to use phytohormones to interact with their host plants, or to regulate their own development.
PMID: 33064769
PLoS One , IF:2.74 , 2020 , V15 (10) : Pe0240355 doi: 10.1371/journal.pone.0240355
Transcriptome sequencing and endogenous phytohormone analysis reveal new insights in CPPU controlling fruit development in kiwifruit (Actinidia chinensis).
Institute of Special Plants, Chongqing Key Laboratory of Economic Plant Biotechnology, Chongqing University of Arts and Sciences, Yongchuan, Chongqing, China.; Department of Biological Sciences, University of Toronto, Scarborough, Ontario, Canada.; College of Horticulture and Gardening, Institute of Horticulture Plants, Yangtze University, Jingzhou, Hubei, China.
Kiwifruit (Actinidia chinensis) is a rich nutritious fruit crop owing to a markedly higher content of vitamin C and minerals. To promote fruit set and to increase the yield of kiwifruit, forchlorfenuron (CPPU) has been widely applied. However, the molecular details regarding CPPU controlling kiwifruit development, especially at the fastest fruit growth stage, remain unknown. In the present study, we measured the effect of CPPU on developmental regulation in red-fleshed kiwifruit (Actinidia chinensis 'Hongyang'). Additionally, a cytological analysis was performed to clarify the precise changes in the cell structure of the CPPU-treated kiwifruits. Moreover, the concentration of endogenous phytohormones, including indoleacetic acid (IAA), zeatin (ZT), gibberellic acid 3 (GA3), and abscisic acid (ABA), were measured by Enzyme-linked Immunosorbent Assay (ELISA). Furthermore, RNA-Seq was performed to dissect the complicated molecular mechanisms, with a focus on biosynthesis, metabolism, and signaling compounds, such as endogenous hormones, sugars, and L-ascorbic acid. Our results demonstrated that CPPU treatment not only regulates the size and weight of a single fruit but also improves the quality in 'Hongyang' kiwifruit through the accumulation of both soluble sugar and vitamin C. It was also seen that CPPU regulates kiwifruit development by enhancing cell expansion of epidermal cells and parenchyma cells, while, promoting cell division of subepidermal cells. Additionally, CPPU significantly increased the gibberellin and cytokinin biosynthetic pathway and signaling, while repressing auxin and ABA biosynthetic pathway; thus, signaling plays an essential role in CPPU controlling kiwifruit development. Notably, transcriptomic analysis revealed that a total of 2244 genes, including 352 unannotated genes, were differentially expressed in kiwifruits because of CPPU treatment, including 127 transcription factors. These genes are mainly enriched in plant hormone signal transduction, photosynthesis, MAPK signaling pathway, starch and sucrose metabolism, and phenylpropanoid biosynthesis. Overall, our results highlight that CPPU regulation of kiwifruit development is mainly associated with an antagonistic and/or synergistic regulatory role of endogenous phytohormones, and enhancing the energy supply. This provides new insights into the molecular details of CPPU controlling kiwifruit development at the fastest fruit growth stage, which is of agricultural importance for kiwifruit breeding and crop improvement.
PMID: 33044982
PLoS One , IF:2.74 , 2020 , V15 (10) : Pe0239382 doi: 10.1371/journal.pone.0239382
Comparative transcriptome analysis of flower bud transition and functional characterization of EjAGL17 involved in regulating floral initiation in loquat.
Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Beibei, Chongqing, China.; Academy of Agricultural Sciences of Southwest University, State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Beibei, Chongqing, China.
Floral initiation plays a critical role for reproductive success in plants, especially fruit trees. However, little information is known on the mechanism of the initiation in loquat (Eriobotrya japonica Lindl.). Here, we used transcriptomic, expression and functional analysis to investigate the candidate genes in floral initiation in loquat. Comparative transcriptome analysis showed differentially expressed genes (DEGs) were mainly enriched in the metabolic pathways of plant hormone signal transduction. The DEGs were mainly involved in the gibberellin, auxin, cytokinin, abscisic acid, salicylic acid and ethylene signaling pathways. Meanwhile, some transcription factors, including MADS-box (MCM1, AGAMOUS, DEFICIENS and SRF), MYB (Myeloblastosis), TCP (TEOSINTE BRANCHED 1, CYCLOIDEA and PCF1), WOX (WUSCHEL-related homeobox) and WRKY (WRKY DNA-binding protein), were significantly differentially expressed. Among these key DEGs, we confirmed that an AGL17 ortholog EjAGL17 was significantly upregulated at the flower bud transition stage. Phylogenetic tree analysis revealed that EjAGL17 was grouped into an AGL17 clade of MADS-box transcription factors. Protein sequence alignment showed that EjAGL17 included a distinctive C-terminal domain. Subcellular localization of EjAGL17 was found only in the nucleus. Expression levels of EjAGL17 reached the highest at the development stage of flower bud transition. Moreover, ectopic expression of EjAGL17 in Arabidopsis significantly exhibited early flowering. Our study provides abundant resources of candidate genes for studying the mechanisms underlying the floral initiation in loquat and other Rosaceae species.
PMID: 33031442
Funct Plant Biol , IF:2.617 , 2020 Oct doi: 10.1071/FP20253
Transcriptome profiling to identify tepal cell enlargement and pigmentation genes and the function of LtEXLB1 in Lilium tsingtauense.
To understand the molecular mechanism underlying tepal development and pigmentation in Lilium tsingtauense Gilg, we performed whole-transcriptome profiles from closed buds at the greenish tepal stage (CBS), the full-bloom with un-horizontal tepal stage (UFS), and the completely opened bud with reflected tepal stage (RFS) of L. tsingtauense. More than 95699 transcripts were generated using a de novo assembly approach. Gene ontology and pathway analysis of the assembled transcripts revealed carbon metabolism is involved in tepal development and pigmentation. In total, 8171 differentially expression genes (DEGs) in three tepal stages were identified. Among these DEGs, ~994 genes putatively encoded transcription factors (TFs), whereas 693 putatively encoded protein kinases. Regarding hormone pathways, 51 DEGs involved in auxin biosynthesis and signalling and 10 DEGs involved in ethylene biosynthesis and signalling. We also isolated seven LtEXPANSINs, including four EXPAs, one EXPB, one EXLA and one EXLB. LtEXLB1 (GenBank: MN856627) was expressed at higher levels in UFS and RFS, compared with CBS. Silencing LtEXLB1 in leaf discs and tepals by virus-induced gene silencing significantly decreased cell expansion under rehydration conditions. Further analysis revealed that more cell numbers were existed in the abaxial and adaxial subepidermis in the silenced LtEXLB1 samples. As the first transcriptome of L. tsingtauense, the unigenes are a valuable resource for future studies on tepal development, and LtEXLB1 functions in cell expansion.
PMID: 33059816
Plant Biol (Stuttg) , IF:2.167 , 2020 Oct doi: 10.1111/plb.13202
Melatonin as a regulatory hub of plant hormone levels and action in stress situations.
Department of Plant Biology (Plant Physiology), Faculty of Biology, University of Murcia, 30100, Murcia, Spain.
Melatonin, a molecule first discovered in animal tissues, plays an important role in multiple physiological responses as a possible plant master regulator. It mediates responses to different types of stress, both biotic and abiotic. Melatonin reduces the negative effects associated with stressors, improving the plant response by increasing their stress tolerance. When plants respond to stress situations, they use up a large amount of plant resources through a set of perfectly synchronized actions. Responses mediated by melatonin use the plant' hormones to, after adequate modulation, counteract and overcome the negative action of the stressor. In this paper we review melatonin-plant hormone relationships. Factors that trigger the stress response and the central role of melatonin are analyzed. An extensive analysis of current studies shows that melatonin modulates the metabolism of plant hormones (biosynthesis and catabolism), the rise or fall in their endogenous levels, the regulation of signaling elements, and how melatonin affects in the final response of auxin, gibberellins, cytokinins, abscisic acid, ethylene, salicylic acid, jasmonates, brassinosteroids, polyamines and strigolactones. Lastly, a general overview of melatonin s actions and its regulatory role at a global level is provided, and proposals for future research are made.
PMID: 33098247
Plant Direct , IF:1.725 , 2020 Oct , V4 (10) : Pe00273 doi: 10.1002/pld3.273
Role of Arabidopsis RAB5 GEF vps9a in maintaining potassium levels under sodium chloride stress.
National Centre for Biological Sciences TIFR Bangalore Karnataka India.
Salt stress is one of the major factors impacting crop productivity worldwide. Through a variety of effector and signaling pathways, plants achieve survival under salinity stress by maintaining high cytosolic potassium/sodium ion (K(+)/Na(+)) ratios, preventing Na(+) cytotoxicity, and retaining osmotic balance. Ras-related protein 5 (Rab5) members are involved in the trafficking of endosomes to the vacuole or plasma membrane (PM). The vacuolar protein sorting- associated protein 9 (vps9a) encodes the single guanine nucleotide exchange factor (GEF) that activates all three known Rab5 proteins in Arabidopsis thaliana. Previous work from our group has reported the critical function of vps9a for the operation of salt-induced endocytic pathway, as well as the expansion of endomembrane compartments under saline stress conditions. Here we show an additional role of vps9a in plant response to salt stress via maintenance of K(+) status of the cell rather than Na(+) homeostasis. Our results show that roots from vps9a-2 mutant, subjected to 100 mM NaCl, display alterations in transcript levels of genes involved in the K(+) homeostasis pathway. Concurrent with the observed sensitivity of vps9a-2 mutant under NaCl stress, exposure to low K(+) environments resulted in growth retardation, and reduced rate of endocytosis. Furthermore, vps9a-2 mutant displays reduced expression of auxin reporter, Direct Repeat-5 (DR5), and alterations in polarity and abundance of auxin efflux carrier PIN- FORMED2 (PIN2). Imposition of NaCl stress was found to be restrictive to the elongation capacity of cells in the root elongation zone of vps9a-2 mutant. Together our results indicate that alterations in K(+) homeostasis and associated cellular changes causing increased cell wall pH, contribute to diminished root growth and compromised survival of vps9a-2 mutant under salt stress conditions.
PMID: 33103044
Plant Signal Behav , IF:1.671 , 2020 Oct : P1837544 doi: 10.1080/15592324.2020.1837544
Phytohormones: structural and functional relationship to purine nucleotides and some pharmacologic agents.
Faculty of Life Sciences & Education, University of South Wales , Cardiff, UK.
Structural components of second messenger signaling (nucleotides and associated enzyme systems) within plant and animal cells have more in common than the hormones that initiate metabolic and functional changes. Neurotransmitters and hormones of mammalian pharmacologic classes relate to purine nucleotides in respect of chemical structure and the molecular changes they initiate. This study compares the molecular structures of purine nucleotides with compounds from the abscisic acid, auxin, brassinosteroid, cytokinin, gibberellin, and jasmonate classes by means of a computational program. The results illustrate how phytohomones relate to each other through the structures of nucleotides and cyclic nucleotides. Molecular similarity within the phytohormone structures relates to synergism, antagonism and the modulation of nucleotide function that regulates germination and plant development. As with the molecular evolution of mammalian hormones, cell signaling and cross-talk within the phytohormone classes is purine nucleotide centered.
PMID: 33100143
Plant Signal Behav , IF:1.671 , 2020 Oct , V15 (10) : P1794394 doi: 10.1080/15592324.2020.1794394
Nitrate deficiency induces differential endocytosis in roots through NRT1.1.
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University , Tai'an, China.; College of Horticulture, Qingdao Agricultural University , Qingdao, China.
Roots grow asymmetrically, sometimes helically, around their growth direction likely to facilitate environmental sensing. We recently demonstrated that nitrate deficiency induces root coiling on horizontal surface through nitrate transporter/sensor NRT1.1 and PIN2- and AUX-mediated polar auxin transport. Here, we show that nitrate deficiency or NRT1.1 loss-of-function induces differential distribution of PIN2 between the future concave and concave sides in root epidermal cells. Treatment with pharmacological drugs suggests that enhanced endocytosis at the future convex side leads to reduced plasma membrane (PM) association of PIN2. A reduction of PIN2 at the PM would maintain a low auxin response to further enhance endocytosis at the convex side, leading to root coiling.
PMID: 32686596