Trends Plant Sci , IF:14.416 , 2021 May doi: 10.1016/j.tplants.2021.04.003
Cell Wall and Hormone Interplay Controls Growth Asymmetry.
Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China.; College of Life Sciences, Hebei Agriculture University, Baoding 071001, China.; Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China. Electronic address: lixj@bjfu.edu.cn.
Plant cell elongation and expansion require the biosynthesis and remodeling of cell wall composition. Recently, Aryal et al. reported how feedback between the cell wall and the auxin response controls differential growth in apical hook development.
PMID: 33958277
Nat Plants , IF:13.256 , 2021 May , V7 (5) : P633-643 doi: 10.1038/s41477-021-00919-9
Two types of bHLH transcription factor determine the competence of the pericycle for lateral root initiation.
Department of Biology, Graduate School of Science, Osaka University, Osaka, Japan.; Graduate School of Science and Technology, Nara Institute of Science and Technology, Nara, Japan.; Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.; Global Zero Emission Research Center, AIST, Tsukuba, Japan.; RIKEN Center for Sustainable Resource Science, Yokohama, Japan.; Takasaki University of Health and Welfare, Takasaki, Japan.; Greenbio Research Center, Graduate School of Science and Engineering, Saitama University, Saitama, Japan.; Department of Biology, Graduate School of Science, Osaka University, Osaka, Japan. kakimoto@bio.sci.osaka-u.ac.jp.
The molecular basis of the competence of the pericycle cell to initiate lateral root primordium formation is totally unknown. Here, we report that in Arabidopsis, two types of basic helix-loop-helix (bHLH) transcription factors, named PERICYCLE FACTOR TYPE-A (PFA) proteins and PERICYCLE FACTOR TYPE-B (PFB) proteins, govern the competence of pericycle cells to initiate lateral root primordium formation. Overexpression of PFA genes confers hallmark pericycle characteristics, including specific marker gene expression and auxin-induced cell division, and multiple loss-of-function mutations in PFA genes or the repression of PFB target genes results in the loss of this specific pericycle function. PFA and PFB proteins physically interact and are under mutual- and self-regulation, forming a positive feedback loop. This study unveils the transcriptional regulatory system that determines pericycle participation in lateral root initiation.
PMID: 34007039
Mol Plant , IF:12.084 , 2021 May doi: 10.1016/j.molp.2021.05.005
The miR166- SlHB15A Regulatory Module controls Ovule Development and Parthenocarpic Fruit Set under Adverse Temperatures in Tomato.
Institute of Plant Sciences Paris-Saclay, INRAE, CNRS, Universite Paris-Saclay, Orsay 91405, France.; Institut Jean-Pierre Bourgin, INRAE, Versailles, France.; HM Clause, Mas Saint-Pierre, quartier La Galine, Saint-Remy de Provence 13210, France.; Hazera Seeds Ltd, Berurim M.P. Shikmim 7983700, Israel.; Institute of Plant Sciences Paris-Saclay, INRAE, CNRS, Universite Paris-Saclay, Orsay 91405, France. Electronic address: abdelhafid.bendahmane@inrae.fr.
Fruit set is inhibited by adverse temperatures, with consequences on yield. We isolated a tomato mutant producing fruits under non-permissive hot temperatures and identified the causal gene as SlHB15A, belonging to class-III homeodomain leucine-zipper transcription factors (HD-ZipIII). SlHB15A loss-of-function mutants display aberrant ovule development that mimics transcriptional changes occurring in fertilized ovules and leads to parthenocarpic fruit set under optimal and non-permissive temperatures, in field and glasshouse conditions. Under cold growing condition, SlHB15A is subjected to conditional haploinsufficiency and recessive dosage sensitivity controlled by microRNA 166 (miR166). Knockdown of SlHB15A alleles by miR166 leads to a continuum of aberrant ovules correlating with parthenocarpic fruit set. Consistent with this, plants harboring SlHB15A-miRNA166 resistant allele developed normal ovules and were unable to set parthenocarpic fruit under cold condition. DNA affinity purification sequencing (DAP-seq) and RNAseq analyses revealed SlHB15A is a bifunctional transcription factor, expressing in the ovule integument. SlHB15A binds to the promoters of auxin genes to repress auxin signaling and to ethylene genes to activate their expression. Survey of tomato genetic biodiversity identified pat and pat-1, two historical parthenocarpic mutants, as alleles of SlHB15A. Our finding demonstrates the role of SlHB15A as a sentinel to prevent fruit set in the absence of fertilization and provides a mean to enhance fruiting under extreme temperatures.
PMID: 33964458
Mol Plant , IF:12.084 , 2021 May , V14 (5) : P708-710 doi: 10.1016/j.molp.2021.02.008
The mechanism of auxin transport in lateral root spacing.
Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium.; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium. Electronic address: tobee@psb.vib-ugent.be.; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Lab of Plant Growth Analysis, Ghent University Global Campus, Incheon 21985, Republic of Korea; Department of Plants and Crops, Ghent University, 9000 Ghent, Belgium. Electronic address: steffen.vanneste@ugent.be.
PMID: 33640514
Plant Cell , IF:9.618 , 2021 May , V33 (3) : P566-580 doi: 10.1093/plcell/koaa037
Natural allelic variation in a modulator of auxin homeostasis improves grain yield and nitrogen use efficiency in rice.
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.; Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK.; Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California 92093, USA.; State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China.; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.; National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.; State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510640, China.; Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing 210095, China.
The external application of nitrogen (N) fertilizers is an important practice for increasing crop production. However, the excessive use of fertilizers significantly increases production costs and causes environmental problems, making the improvement of crop N-use efficiency (NUE) crucial for sustainable agriculture in the future. Here we show that the rice (Oryza sativa) NUE quantitative trait locus DULL NITROGEN RESPONSE1 (qDNR1), which is involved in auxin homeostasis, reflects the differences in nitrate (NO3-) uptake, N assimilation, and yield enhancement between indica and japonica rice varieties. Rice plants carrying the DNR1indica allele exhibit reduced N-responsive transcription and protein abundance of DNR1. This, in turn, promotes auxin biosynthesis, thereby inducing AUXIN RESPONSE FACTOR-mediated activation of NO3- transporter and N-metabolism genes, resulting in improved NUE and grain yield. We also show that a loss-of-function mutation at the DNR1 locus is associated with increased N uptake and assimilation, resulting in improved rice yield under moderate levels of N fertilizer input. Therefore, modulating the DNR1-mediated auxin response represents a promising strategy for achieving environmentally sustainable improvements in rice yield.
PMID: 33955496
Curr Biol , IF:9.601 , 2021 May , V31 (9) : PR449-R451 doi: 10.1016/j.cub.2021.03.070
Plant cell biology: PIN polarity maintained.
Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, DE-14476 Potsdam-Golm, Germany.; Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, Karl-Liebknecht-Str. 24-25, Building 20, DE-14476 Potsdam-Golm, Germany. Electronic address: markus.grebe@uni-potsdam.de.
PIN-FORMED (PIN) polar protein localization directs transport of the growth and developmental regulator auxin in plants. Once established after cytokinesis, PIN polarity requires maintenance. Now, direct interactions between PIN, MAB4/MEL and PID proteins suggest self-reinforced maintenance of PIN polarity through limiting lateral diffusion.
PMID: 33974874
Curr Biol , IF:9.601 , 2021 May , V31 (9) : P1918-1930.e5 doi: 10.1016/j.cub.2021.02.028
AGC kinases and MAB4/MEL proteins maintain PIN polarity by limiting lateral diffusion in plant cells.
Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria; Department of Experimental Plant Biology, Faculty of Science, Charles University, 12844 Prague, Czechia; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, 9052 Ghent, Belgium.; Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, the Netherlands; Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, 3584 CH Utrecht, the Netherlands.; Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria.; Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan.; Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, the Netherlands.; Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria; Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, (BOKU), 1190 Vienna, Austria.; Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria; Department of Experimental Plant Biology, Faculty of Science, Charles University, 12844 Prague, Czechia.; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, 9052 Ghent, Belgium.; Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 BE Leiden, the Netherlands. Electronic address: r.offringa@biology.leidenuniv.nl.; Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria. Electronic address: jiri.friml@ist.ac.at.
Polar subcellular localization of the PIN exporters of the phytohormone auxin is a key determinant of directional, intercellular auxin transport and thus a central topic of both plant cell and developmental biology. Arabidopsis mutants lacking PID, a kinase that phosphorylates PINs, or the MAB4/MEL proteins of unknown molecular function display PIN polarity defects and phenocopy pin mutants, but mechanistic insights into how these factors convey PIN polarity are missing. Here, by combining protein biochemistry with quantitative live-cell imaging, we demonstrate that PINs, MAB4/MELs, and AGC kinases interact in the same complex at the plasma membrane. MAB4/MELs are recruited to the plasma membrane by the PINs and in concert with the AGC kinases maintain PIN polarity through limiting lateral diffusion-based escape of PINs from the polar domain. The PIN-MAB4/MEL-PID protein complex has self-reinforcing properties thanks to positive feedback between AGC kinase-mediated PIN phosphorylation and MAB4/MEL recruitment. We thus uncover the molecular mechanism by which AGC kinases and MAB4/MEL proteins regulate PIN localization and plant development.
PMID: 33705718
New Phytol , IF:8.512 , 2021 May doi: 10.1111/nph.17426
LAZY2 controls rice tiller angle through regulating starch biosynthesis in gravity-sensing cells.
Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.; University of Chinese Academy of Sciences, Beijing, 100049, China.; State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, China.; State Key Laboratory of Rice Biology, Key Laboratory of the Ministry of Agriculture for Nuclear-Agricultural Sciences, Department of Applied Biosciences, Zhejiang University, Hangzhou, 310029, China.; CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
Rice (Oryza sativa) tiller angle is a key component for achieving ideal plant architecture and higher grain yield. However, the molecular mechanism underlying rice tiller angle remains elusive. We characterized a novel rice tiller angle mutant lazy2 (la2) and isolated the causative gene LA2 through map-based cloning. Biochemical, molecular and genetic studies were conducted to elucidate the LA2-involved tiller angle regulatory mechanism. The la2 mutant shows large tiller angle with impaired shoot gravitropism and defective asymmetric distribution of auxin. We found that starch granules in amyloplasts are completely lost in the gravity-sensing leaf sheath base cells of la2, whereas the seed development is not affected. LA2 encodes a novel chloroplastic protein that can interact with the starch biosynthetic enzyme Oryza sativa plastidic phosphoglucomutase (OspPGM) to regulate starch biosynthesis in rice shoot gravity-sensing cells. Genetic analysis showed that LA2 regulates shoot gravitropism and tiller angle by acting upstream of LA1 to mediate lateral auxin transport. Our studies revealed that LA2 acts as a novel regulator of rice tiller angle by specifically regulating starch biosynthesis in gravity-sensing cells, and established the framework of the starch-statolith-dependent rice tiller angle regulatory pathway, providing new insights into the rice tiller angle regulatory network.
PMID: 34042184
New Phytol , IF:8.512 , 2021 May doi: 10.1111/nph.17447
Aldoximes are precursors of auxins in Arabidopsis and maize.
Horticultural Sciences Department, University of Florida, Gainesville, 32611.; Department of Chemistry, University of Florida, Gainesville, 32611.; Department of Medicinal Chemistry, University of Florida, Gainesville, 32610.; Center for Medical, Agricultural and Veterinary Entomology, U.S. Department of Agriculture-Agricultural Research Service, Gainesville, 32608.; Plant Molecular and Cellular Biology Graduate Program, University of Florida, Gainesville, FL, USA.
Two natural auxins, phenylacetic acid (PAA) and indole-3-acetic acid (IAA), play crucial roles in plant growth and development. One route of IAA biosynthesis uses the glucosinolate intermediate indole-3-acetaldoxime (IAOx) as a precursor, which is thought to occur only in glucosinolate-producing plants in Brassicales. A recent study showed that overproducing phenylacetaldoxime (PAOx) in Arabidopsis increases PAA production. However, it remains unknown whether this increased PAA results from hydrolysis of PAOx-derived benzyl glucosinolate or, like IAOx-derived IAA, is directly converted from PAOx. If glucosinolate hydrolysis is not required, aldoxime-derived auxin biosynthesis may occur beyond Brassicales. To better understand aldxoime-derived auxin biosynthesis, we conducted isotope labeled aldoxime feeding assay using an Arabidopsis glucosinolate-deficient mutant sur1 and maize, and transcriptomics analysis. Our study demonstrates that the conversion of PAOx to PAA does not require glucosinolates in Arabidopsis. Furthermore, maize produces PAA and IAA from PAOx and IAOx respectively indicating that aldoxime-derived auxin biosynthesis also occurs in maize. Considering that aldoxime production occurs widely in the plant kingdom, aldoxime-derived auxin biosynthesis is likely more widespread than originally believed. A genome-wide transcriptomics study using PAOx-overproduction plants identified complex metabolic networks among IAA, PAA, phenylpropanoid, and tryptophan metabolism.
PMID: 33959967
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 May doi: 10.1101/cshperspect.a039883
Structural Aspects of Auxin Signaling.
Department of Biology, Duke University, Durham, North Carolina 27708, USA.; Center for Science and Engineering Living Systems (CSELS), Washington University, St. Louis, Missouri 63130, USA.; Center for Engineering Mechanobiology, Washington University, St. Louis, Missouri 63130, USA.
Auxin signaling regulates growth and developmental processes in plants. The core of nuclear auxin signaling relies on just three components: TIR1/AFBs, Aux/IAAs, and ARFs. Each component is itself made up of several domains, all of which contribute to the regulation of auxin signaling. Studies of the structural aspects of these three core signaling components have deepened our understanding of auxin signaling dynamics and regulation. In addition to the structured domains of these components, intrinsically disordered regions within the proteins also impact auxin signaling outcomes. New research is beginning to uncover the role intrinsic disorder plays in auxin-regulated degradation and subcellular localization. Structured and intrinsically disordered domains affect auxin perception, protein degradation dynamics, and DNA binding. Taken together, subtle differences within the domains and motifs of each class of auxin signaling component affect signaling outcomes and specificity.
PMID: 34001533
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 May doi: 10.1101/cshperspect.a040089
Modeling Auxin Signaling in Roots: Auxin Computations.
Computational Developmental Biology Group, Utrecht University, Utrecht 3584 CH, The Netherlands.
Auxin signaling and patterning is an inherently complex process, involving polarized auxin transport, metabolism, and signaling, its effect on developmental zones, as well as growth rates, and the feedback between all these different aspects. This complexity has led to an important role for computational modeling in unraveling the multifactorial roles of auxin in plant developmental and adaptive processes. Here we discuss the basic ingredients of auxin signaling and patterning models for root development as well as a series of key modeling studies in this area. These modeling studies have helped elucidate how plants use auxin signaling to compute the size of their root meristem, the direction in which to grow, and when and where to form lateral roots. Importantly, these models highlight how auxin, through patterning of and collaborating with other factors, can fulfill all these roles simultaneously.
PMID: 34001532
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 May doi: 10.1101/cshperspect.a040097
Computational Models of Auxin-Driven Patterning in Shoots.
Department of Computer Science, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
Auxin regulates many aspects of plant development and behavior, including the initiation of new outgrowth, patterning of vascular systems, control of branching, and responses to the environment. Computational models have complemented experimental studies of these processes. We review these models from two perspectives. First, we consider cellular and tissue-level models of interaction between auxin and its transporters in shoots. These models form a coherent body of results exploring different hypotheses pertinent to the patterning of new outgrowth and vascular strands. Second, we consider models operating at the level of plant organs and entire plants. We highlight techniques used to reduce the complexity of these models, which provide a path to capturing the essence of studied phenomena while running simulations efficiently.
PMID: 34001531
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 May , V13 (5) doi: 10.1101/cshperspect.a039917
Noncanonical Auxin Signaling.
Crop Genetics Department, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom.
Auxin influences all aspects of plant growth and development and exerts its function at scales ranging from the subcellular to the whole-organism level. A canonical mechanism for auxin signaling has been elucidated, which is based on derepression of downstream genes via ubiquitin-mediated degradation of transcriptional repressors. While the combinatorial nature of this canonical pathway provides great potential for specificity in the auxin response, alternative noncanonical signaling pathways required to mediate certain processes have been identified. One such pathway affects gene regulation in a manner that is reminiscent of mechanisms employed in animal hormone signaling, while another triggers transcriptional changes through auxin perception at the plasma membrane and the stabilization of transcriptional repressors. In some cases, the exact perception mechanisms and the nature of the receptors involved are yet to be revealed. In this review, we describe and discuss current knowledge on noncanonical auxin signaling and highlight unresolved questions surrounding auxin biology.
PMID: 33431583
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 May , V13 (5) doi: 10.1101/cshperspect.a040105
Chemical Biology in Auxin Research.
Department of Biochemistry, Okayama University of Science, Okayama City 700-0005, Japan.
Molecular genetic and structural studies have revealed the mechanisms of fundamental components of key auxin regulatory pathways consisting of auxin biosynthesis, transport, and signaling. Chemical biology methods applied in auxin research have been greatly expanded through the understanding of auxin regulatory pathways. Many small-molecule modulators of auxin metabolism, transport, and signaling have been generated on the basis of the outcomes of genetic and structural studies on auxin regulatory pathways. These chemical modulators are now widely used as essential tools for dissecting auxin biology in diverse plants. This review covers the structures, primary targets, modes of action, and applications of chemical tools in auxin biosynthesis, transport, and signaling.
PMID: 33431581
Sci Total Environ , IF:6.551 , 2021 May , V788 : P147735 doi: 10.1016/j.scitotenv.2021.147735
Mechanisms of the enantioselective effects of phenoxyalkanoic acid herbicides DCPP and MCPP.
Institute of Nuclear Agricultural Sciences, Key laboratory of Nuclear Agricultural Sciences of Ministry of Agriculture of PRC and Zhejiang Province, Zhejiang University, Hangzhou 310058, China.; Department of Applied Bioscience, College of agriculture and biotechnology, Zhejiang University, Hangzhou 310029, China.; Hangzhou Botanical Garden, No.1, Taoyuan, Xihu District, Hangzhou 310012, China.; Institute of Nuclear Agricultural Sciences, Key laboratory of Nuclear Agricultural Sciences of Ministry of Agriculture of PRC and Zhejiang Province, Zhejiang University, Hangzhou 310058, China. Electronic address: qfye@zju.edu.cn.; Department of Environmental Sciences, University of California, Riverside, CA 92521, USA.
Phenoxyalkanoic acids (PAAs), synthetic indole-3-acetic acid (IAA) auxin mimics, are widely used as herbicides. Many PAAs are chiral molecules and show strong enantioselectivity in their herbicidal activity; however, there is a lack of understanding of mechanisms driving enantioselectivity. This study aimed to obtain a mechanistic understanding of PAA enantioselectivity using dichlorprop and mecoprop as model PAA compounds. Molecular docking, in vitro (3)H-IAA binding assay, and surface plasmon resonance analysis showed that the R enantiomer was preferentially combined with TIR1-IAA7 (Transport Inhibitor Response1- Auxin-Responsive Protein IAA7) than the S enantiomer. In vivo tracking using (14)C-PAAs showed a greater absorption of the R enantiomer by Arabidopsis thaliana, and further comparatively enhanced translocation of the R enantiomer to the nucleus where the auxin co-receptor is located. These observations imply that TIR1-IAA7 is a prior target for DCPP and MCPP, and that PAA enantioselectivity occurs because the R enantiomer has a stronger binding affinity for TIR1-IAA7 as well as a greater plant absorption and translocation capability than the S enantiomer. The improved understanding of PAA enantioselectivity is of great significance, as the knowledge may be used to design "green" molecules, such as R enantiomer enriched products, leading to improved plant management and environmental sustainability.
PMID: 34029804
Sci Total Environ , IF:6.551 , 2021 May , V787 : P147510 doi: 10.1016/j.scitotenv.2021.147510
Insights into the mechanism of multi-walled carbon nanotubes phytotoxicity in Arabidopsis through transcriptome and m6A methylome analysis.
Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China.; Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China; College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, China.; College of Agronomy, Hunan Agricultural University, Changsha, Hunan 410128, China; Crop Gene Engineering Key Laboratory of Hunan Province, Changsha, Hunan, 410128, China.; College of Agronomy, Hunan Agricultural University, Changsha, Hunan 410128, China; Crop Gene Engineering Key Laboratory of Hunan Province, Changsha, Hunan, 410128, China. Electronic address: xiongene@hunau.edu.cn.; Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China. Electronic address: sujianguang@caas.cn.; National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Singapore; Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, 117543, Singapore. Electronic address: anyansci@gmail.com.
With the increasing production and wide application of carbon nanotubes (CNTs), they are inevitably released into the natural environment and ecosystems, where plants are the main primary producers. Hence, it is imperative to understand the toxic effects of CNTs on plants. The molecular mechanisms underlying the toxic effects of CNTs on plants are still unclear. Therefore, in the present study, we investigated the effects of high concentrations of multi-walled CNTs (MWCNTs) on Arabidopsis. Root elongation and leaf development were severely inhibited after MWCNT exposure. Excess production of H2O2, O2(-), and malondialdehyde was observed, indicating that MWCNTs induced oxidative stress. The antioxidant system was activated to counter MWCNTs-induced oxidative stress. Combinatorial transcriptome and m6A methylome analysis revealed that MWCNTs suppressed auxin signaling and photosynthesis. Reactive oxygen species metabolism, toxin metabolism, and plant responses to pathogens were enhanced to cope with the phytotoxicity of MWCNTs. Our results provide new insights into the molecular mechanisms of CNT phytotoxicity and plant defense responses to CNTs.
PMID: 33991908
Genomics , IF:6.205 , 2021 May doi: 10.1016/j.ygeno.2021.05.027
Multi-omics analysis reveals the ontogenesis of basal chichi in Ginkgo biloba L.
State Forestry and Grassland Administration Key Laboratory of Silviculture in Downstream Areas of the Yellow River, Forestry College of Shandong Agricultural University, Tai'an, Shandong 271018, China.; State Forestry and Grassland Administration Key Laboratory of Silviculture in Downstream Areas of the Yellow River, Forestry College of Shandong Agricultural University, Tai'an, Shandong 271018, China. Electronic address: sunlimin06@163.com.; State Forestry and Grassland Administration Key Laboratory of Silviculture in Downstream Areas of the Yellow River, Forestry College of Shandong Agricultural University, Tai'an, Shandong 271018, China. Electronic address: xing@sdau.edu.cn.
Chichi is a unique biological phenomenon observed in Ginkgo biloba L.. In this study, multi-omics analysis was used to compare basal chichi (C) with roots (R) and stems (S) to explore the regulatory mechanisms of basal chichi ontogenesis. The results showed that compared with roots and stems, the tZ, SA and ABA contents in basal chichi were the highest, and the ratio of IAA/tZ was the lowest. Nucleotides and their derivatives in basal chichi were upregulated, and phenylpropane metabolites were downregulated. Some differentially expressed genes (DEGs) strongly correlated to plant hormones were screened. We speculate that auxin and cytokinin are involved in the morphogenesis of basal chichi and that cytokinin plays a major role. The ontogenesis of basal chichi is closely related to environmental stress, and it may be a coping strategy of G. biloba in the face of environmental stress.
PMID: 34048909
Plant J , IF:6.141 , 2021 May doi: 10.1111/tpj.15358
Long-read genome assembly and genetic architecture of fruit shape in the bottle gourd.
Institute of Vegetables, Zhejiang Academy of Agricultural Sciences, 310021, Zhejiang, China.; State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Zhejiang Academy of Agricultural Sciences, 310021, Zhejiang, China.; Biozeron Biotechnology Co, Ltd, Shanghai, 201800, China.; College of Life Science, Jiliang University, Hangzhou, 310018, China.; Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100080, China.; Center for Statistical Genetics, The Pennsylvania State University, Hershey, 17033, Pennsylvania, United States of America.; Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.; Institute of Vegetables, Ningbo Academy of Agricultural Sciences, Ningbo, 315040, China.; College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China.
The bottle gourd (Lagenaria siceraria, Cucurbitaceae) is an important horticultural crop exhibiting tremendous diversity in fruit shape. The genetic architecture of fruit shape variation in this species remains unknown. We assembled a long-read-based, high-quality reference genome (ZAAS_Lsic_2.0) with a contig N50 value over 390-fold greater than the existing reference genomes. We then focused on dissection of fruit shape using a one-step geometric morphometrics (GM)-based functional mapping approach. We identified 11 quantitative trait loci (QTLs) responsible for fruit shape (fsQTLs), reconstructed their visible effects, and revealed syntenic relationships of bottle gourd fsQTLs with 12 fsQTLs previously reported in cucumber, melon or watermelon. Homologs of several well-known and newly identified fruit shape genes, including SUN, OFP, AP2 and auxin transporters, were comapped with bottle gourd QTLs.
PMID: 34043857
Plant J , IF:6.141 , 2021 May doi: 10.1111/tpj.15314
RNA-seq analysis of laser micro-dissected Arabidopsis thaliana leaf epidermis, mesophyll and vasculature defines tissue-specific transcriptional responses to multiple stress treatments.
Australian Research Council Centre of Excellence in Plant Energy Biology, AgriBio Building La Trobe University, Bundoora, Victoria, 3086, Australia.; Australian Research Council Research Hub for Medicinal Agriculture, La Trobe University, AgriBio Building, Bundoora, Victoria, 3086, Australia.; Department of Animal, Plant and Soil Science, La Trobe University, AgriBio Building, Bundoora, Victoria, 3086, Australia.
Acclimation of plants to adverse conditions requires the coordination of gene expression and signalling pathways between tissues and cell types. As the energy and carbon capturing organs, leaves are significantly affected by abiotic and biotic stresses. However, tissue- or cell type-specific analyses of stress responses have focussed on the Arabidopsis root. Here, we comparatively explore the transcriptomes of three leaf tissues (epidermis, mesophyll, vasculature) after induction of diverse stress pathways by chemical stimuli (antimycin A, 3-amino-1,2,4-triazole, methyl viologen, salicylic acid) and UV light in Arabidopsis using laser-capture microdissection followed by RNA-seq. Stimulation of stress pathways caused an overall reduction in the number of genes expressed in a tissue-specific manner, though a small subset gained or changed their tissue-specificity. We find no evidence of a common stress response, with only a few genes consistently responsive to two or more treatments in the analysed tissues. However, differentially expressed genes overlap between tissues for individual treatments. A focussed analysis provided evidence for an interaction of auxin and ethylene that mediates retrograde signalling during mitochondrial dysfunction specifically in the epidermis, and a gene regulatory network defined the hierarchy of interactions. Taken together, we have generated an extensive reference data set that will be valuable for future experiments analysing transcriptional responses on a tissue- or single-cell level. Our results will enable the tailoring of the tissue-specific engineering of stress tolerant plants.
PMID: 33974297
J Exp Bot , IF:5.908 , 2021 May doi: 10.1093/jxb/erab196
Melatonin promotes Arabidopsis primary root growth in an IAA dependent manner.
Key Laboratory of Horticultural Plant Biology Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.; Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute, The Chinese Academy of Agricultural Sciences, Wuhan, Hubei, 430071, China.; College of Life Sciences, Northwest A& F University, Yangling Shaanxi, 712100, China.
Melatonin (MT) has been characterized as growth regulator in plants. MT shares tryptophan as the precursor with indole-3-acetic acid (IAA) but the interplay between MT and IAA remains controversial. In this study, we aimed to dissect relationship between MT and IAA on primary root growth regulation. We observed that low concentrations MT ranged from 10 -9 to 10 -6 M functioned as IAA mimics to promote primary root growth in Arabidopsis wild type as well as pin single and double mutants. Transcriptomic analysis showed that gene expression changed by MT and IAA were moderately correlated. Most of IAA regulated genes were co-regulated by MT, indicating that MT and IAA regulated the similar subset of downstream genes. Inhibition of auxin polar transport impaired MT promoting effect on root growth. MT partially rescued primary root growth defects in pin single and double mutant plants. However, MT treatment had scarcely any effect on primary root growth in the presence of high concentration auxin biosynthesis inhibitors TIBA and NPA, or polar transport inhibitor L-AOPP, and could not rescue root length defect of IAA biosynthesis quintuple mutant yucQ. Therefore, we proposed that MT promoted primary root growth in an IAA dependent manner.
PMID: 34009365
J Exp Bot , IF:5.908 , 2021 May doi: 10.1093/jxb/erab202
Getting to the Root of Belowground High Temperature Responses in Plants.
Ghent University, Department of Plant Biotechnology and Bioinformatics, B-9052 Ghent, Belgium.; VIB Center for Plant Systems Biology, B-9052 Ghent, Belgium.; Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences (BOKU), Muthgasse 18, 1190 Vienna, Austria.; Faculty of Biology, Department of Molecular Plant Physiology (MoPP), University of Freiburg, 79104 Freiburg, Germany.; Center for Integrative Biological Signalling Studies (CIBSS), University of Freiburg, 79104 Freiburg, Germany.
The environment is continuously challenging plants. As a response, plants use various coping strategies, such as adaptation of their growth. Thermomorphogenesis is a specific growth adaptation that promotes organ growth in response to moderately high temperature. This would eventually enable plants to cool down by dissipating the heat. Although well understood for shoot organs, the thermomorphogenesis response in roots only recently obtained increasing research attention. Accordingly, in the last few years, the hormonal responses and underlying molecular players important for root thermomorphogenesis were revealed. Other responses triggered by high temperature in the root encompass modifications of overall root architecture and interactions with the soil environment, with consequences on the whole plant. Here, we review the scientific knowledge and highlight the current understanding on roots responding to moderately high and extreme temperature.
PMID: 33970267
J Exp Bot , IF:5.908 , 2021 May , V72 (10) : P3489-3492 doi: 10.1093/jxb/erab148
Xylem versus phloem in secondary growth: a balancing act mediated by gibberellins.
Department of Organismal Biology, Physiological Botany, Linnean Centre for Plant Biology, Uppsala University, Ullsv. 24E, SE-756 51, Uppsala, Sweden.
PMID: 33948652
J Exp Bot , IF:5.908 , 2021 May , V72 (10) : P3688-3703 doi: 10.1093/jxb/erab106
Auxin signaling and vascular cambium formation enable storage metabolism in cassava tuberous roots.
Friedrich-Alexander-University Erlangen-Nuremberg, Department of Biology, Division of Biochemistry, Staudtstrasse 5, Erlangen, Germany.; International Institute for Tropical Agriculture, Ibadan, Oyo State, Nigeria.; Institute for Sustainable Plant Protection, CNR, Bari, Italy.; Technical University Kaiserslautern, Department of Biology, Division of Plant Physiology, Erwin-Schrodinger-Str. 22, Kaiserslautern, Germany.; Institute for Biomedical Technologies, CNR, Bari, Italy.
Cassava storage roots are among the most important root crops worldwide, and represent one of the most consumed staple foods in sub-Saharan Africa. The vegetatively propagated tropical shrub can form many starchy tuberous roots from its stem. These storage roots are formed through the activation of secondary root growth processes. However, the underlying genetic regulation of storage root development is largely unknown. Here we report distinct structural and transcriptional changes occurring during the early phases of storage root development. A pronounced increase in auxin-related transcripts and the transcriptional activation of secondary growth factors, as well as a decrease in gibberellin-related transcripts were observed during the early stages of secondary root growth. This was accompanied by increased cell wall biosynthesis, most notably increased during the initial xylem expansion within the root vasculature. Starch storage metabolism was activated only after the formation of the vascular cambium. The formation of non-lignified xylem parenchyma cells and the activation of starch storage metabolism coincided with increased expression of the KNOX/BEL genes KNAT1, PENNYWISE, and POUND-FOOLISH, indicating their importance for proper xylem parenchyma function.
PMID: 33712830
J Exp Bot , IF:5.908 , 2021 May , V72 (10) : P3554-3568 doi: 10.1093/jxb/erab094
Potential interaction between autophagy and auxin during maize leaf senescence.
Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.; University of Chinese Academy of Sciences, Beijing, 100049, China.; Institute of Agricultural Biotechnology, Jilin Academy of Agricultural Sciences, Changchun, Jilin 130124, China.; Engineering Laboratory for Grass-based Livestock Husbandry, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
Leaf senescence is important for crop yield as delaying it can increase the average yield. In this study, population genetics and transcriptomic profiling were combined to dissect its genetic basis in maize. To do this, the progenies of an elite maize hybrid Jidan27 and its parental lines Si-287 (early senescence) and Si-144 (stay-green), as well as 173 maize inbred lines were used. We identified two novel loci and their candidate genes, Stg3 (ZmATG18b) and Stg7 (ZmGH3.8), which are predicted to be members of autophagy and auxin pathways, respectively. Genomic variations in the promoter regions of these two genes were detected, and four allelic combinations existed in the examined maize inbred lines. The Stg3Si-144/Stg7Si-144 allelic combination with lower ZmATG18b expression and higher ZmGH3.8 expression could distinctively delay leaf senescence, increase ear weight and the improved hybrid of NIL-Stg3Si-144/Stg7Si-144 x Si-144 significantly reduced ear weight loss under drought stress, while opposite effects were observed in the Stg3Si-287/Stg7Si-287 combination with a higher ZmATG18b expression and lower ZmGH3.8 expression. Thus, we identify a potential interaction between autophagy and auxin which could modulate the timing of maize leaf senescence.
PMID: 33684202
J Exp Bot , IF:5.908 , 2021 May , V72 (10) : P3806-3820 doi: 10.1093/jxb/erab086
A SlMYB75-centred transcriptional cascade regulates trichome formation and sesquiterpene accumulation in tomato.
Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing, China.; Department of Horticulture and Landscape Architecture, Oklahoma State University, Stillwater, OK, USA.; Horticulture Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu, China.
Tomato trichomes act as a mechanical and chemical barrier against pests. An R2R3 MYB transcription factor gene, SlMYB75, is highly expressed in type II, V, and VI trichomes. SlMYB75 protein is located in the nucleus and possesses transcriptional activation activity. Down-regulation of SlMYB75 increased the formation of type II, V, and VI trichomes, accumulation of delta-elemene, beta-caryophyllene, and alpha-humulene in glandular trichomes, and tolerance to spider mites in tomato. In contrast, overexpression of SlMYB75 inhibited trichome formation and sesquiterpene accumulation, and increased plant sensitivity to spider mites. RNA-Seq analyses of the SlMYB75 RNAi line indicated massive perturbation of the transcriptome, with a significant impact on several classes of transcription factors. Expression of the MYB genes SlMYB52 and SlTHM1 was strongly reduced in the RNAi line and increased in the SlMYB75-overexpressing line. SlMYB75 protein interacted with SlMYB52 and SlTHM1 and activated their expression. SlMYB75 directly targeted the promoter of the cyclin gene SlCycB2, increasing its activity. The auxin response factor SlARF4 directly targeted the promoter of SlMYB75 and inhibited its expression. SlMYB75 also bound to the promoters of the terpene synthase genes SlTPS12, SlTPS31, and SlTPS35, inhibiting their transcription. Our findings indicate that SlMYB75 perturbation affects several transcriptional circuits, resulting in altered trichome density and metabolic content.
PMID: 33619530
J Exp Bot , IF:5.908 , 2021 May , V72 (10) : P3647-3660 doi: 10.1093/jxb/erab089
Auxin and gibberellin signaling cross-talk promotes hypocotyl xylem expansion and cambium homeostasis.
ZMBP - Center for Plant Molecular Biology, University of Tubingen, Auf der Morgenstelle 32, D-72076 Tubingen, Germany.; Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076 Tubingen, Germany.
During secondary growth, the thickening of plant organs, wood (xylem) and bast (phloem) is continuously produced by the vascular cambium. In Arabidopsis hypocotyl and root, we can distinguish two phases of secondary growth based on cell morphology and production rate. The first phase, in which xylem and phloem are equally produced, precedes the xylem expansion phase in which xylem formation is enhanced and xylem fibers differentiate. It is known that gibberellins (GA) trigger this developmental transition via degradation of DELLA proteins and that the cambium master regulator BREVIPEDICELLUS/KNAT1 (BP/KNAT1) and receptor like kinases ERECTA and ERL1 regulate this process downstream of GA. However, our understanding of the regulatory network underlying GA-mediated secondary growth is still limited. Here, we demonstrate that DELLA-mediated xylem expansion in Arabidopsis hypocotyl is mainly achieved through DELLA family members RGA and GAI, which promote cambium senescence. We further show that AUXIN RESPONSE FACTOR 6 (ARF6) and ARF8, which physically interact with DELLAs, specifically repress phloem proliferation and induce cambium senescence during the xylem expansion phase. Moreover, the inactivation of BP in arf6 arf8 background revealed an essential role for ARF6 and ARF8 in cambium establishment and maintenance. Overall, our results shed light on a pivotal hormone cross-talk between GA and auxin in the context of plant secondary growth.
PMID: 33619529
J Exp Bot , IF:5.908 , 2021 May , V72 (12) : P4457-4471 doi: 10.1093/jxb/eraa488
Silicon induces adventitious root formation in rice under arsenate stress with involvement of nitric oxide and indole-3-acetic acid.
Amity Institute of Organic Agriculture (AIOA), Amity University, Noida, Noida, Uttar Pradesh.; Department of Biotechnology, Motilal Nehru National Institute of Technology Allahabad, PrayagrajIndia.; 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 1, Granada, Spain.; Plant Physiology Laboratory, Department of Botany, C.M.P. Degree College, A Constituent Post Graduate College of University of Allahabad, Allahabad-211002, India.
Arsenic (As) negatively affects plant development. This study evaluates how the application of silicon (Si) can favor the formation of adventitious roots in rice under arsenate stress (AsV) as a mechanism to mitigate its negative effects. The simultaneous application of AsV and Si up-regulated the expression of genes involved in nitric oxide (NO) metabolism, cell cycle progression, auxin (IAA, indole-3-acetic acid) biosynthesis and transport, and Si uptake which accompanied adventitious root formation. Furthermore, Si triggered the expression and activity of enzymes involved in ascorbate recycling. Treatment with L-NAME (NG-nitro L-arginine methyl ester), 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. Our data suggest that both NO and IAA are essential for Si-mediated adventitious root formation under AsV stress. Interestingly, TIBA (2,3,5-triiodobenzoic acid), a polar auxin transport inhibitor, suppressed adventitious root formation even in the presence of Si and SNP (sodium nitroprusside, an NO donor), suggesting that Si is involved in a mechanism whereby a cellular signal is triggered and that first requires NO formation, followed by IAA biosynthesis.
PMID: 33095869
J Integr Plant Biol , IF:4.885 , 2021 May doi: 10.1111/jipb.13140
Rice SPL10 positively regulates trichome development through expression of HL6 and auxin-related genes.
State Key Laboratory of Agrobiotechnology/Beijing Key Laboratory of Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing, 100193, China.; National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China.; College of Plant Protection, China Agricultural University, Beijing, 100193, China.
Trichomes function in plant defenses against biotic and abiotic stresses; examination of glabrous lines, which lack trichomes, has revealed key aspects of trichome development and function. Tests of allelism in 51 glabrous rice (Oryza sativa) accessions collected worldwide identified OsSPL10 and OsWOX3B as regulators of trichome development in rice. Here, we report that OsSPL10 acts as a transcriptional regulator controlling trichome development. Haplotype and transient expression analyses revealed that variation in the ~700-bp OsSPL10 promoter region is the primary cause of the glabrous phenotype in the indica cultivar WD-17993. Disruption of OsSPL10 by genome editing decreased leaf trichome density and length in the NIL-HL6 background. Plants with genotype OsSPL10(WD-17993) /HL6 generated by crossing WD-17993 with NIL-HL6 also had fewer trichomes in the glumes. HAIRY LEAF6 (HL6) encodes another transcription factor that regulates trichome initiation and elongation, and OsSPL10 directly binds to the HL6 promoter to regulate its expression. Moreover, the transcript levels of auxin-related genes, such as OsYUCCA5 and OsPIN-FORMED1b, were altered in OsSPL10 overexpression and RNAi transgenic lines. Feeding tests using locusts (Locusta migratoria) demonstrated that non-glandular trichomes affect feeding by this herbivore. Our findings provide a molecular framework for trichome development and an ecological perspective on trichome functions. This article is protected by copyright. All rights reserved.
PMID: 34038040
J Integr Plant Biol , IF:4.885 , 2021 May doi: 10.1111/jipb.13111
Phytochrome B interacts with SWC6 and ARP6 to regulate H2A.Z deposition and photomorphogensis in Arabidopsis.
Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China.; School of Life Sciences, Fudan University, Shanghai, 200438, China.
Light serves as a crucial environmental cue that modulates plant growth and development, which is controlled by multiple photoreceptors including the primary red light photoreceptor, phytochrome B (phyB). The signaling mechanism of phyB involves direct interactions with a group of basic helix-loop-helix (bHLH) transcription factors, PHYTOCHROME-INTERACTING FACTORS (PIFs), and the negative regulators of photomorphogenesis, COP1 and SPAs. H2A.Z is an evolutionarily conserved H2A variant that plays essential roles in transcriptional regulation. The replacement of H2A with H2A.Z is catalyzed by the SWR1 complex. Here, we show that the Pfr form of phyB physically interacts with the SWR1 complex subunits SWC6 and ARP6. phyB and ARP6 co-regulate numerous genes in the same direction, some of which are associated with auxin biosynthesis and response including YUC9, which encodes a rate-limiting enzyme in the tryptophan-dependent auxin biosynthesis pathway. Moreover, phyB and HY5/HYH act to inhibit hypocotyl elongation partially through repression of auxin biosynthesis. Based our findings and previous studies, we propose that phyB promotes H2A.Z deposition at YUC9 to inhibit its expression through direct phyB-SWC6/ARP6 interactions, leading to repression of auxin biosynthesis, and thus inhibition of hypocotyl elongation in red light. This article is protected by copyright. All rights reserved.
PMID: 33982818
J Agric Food Chem , IF:4.192 , 2021 May doi: 10.1021/acs.jafc.1c01100
Hormone Orchestrates a Hierarchical Transcriptional Cascade That Regulates Al-Induced De Novo Root Regeneration in Tea Nodal Cutting.
College of Horticulture, Northwest A&F University, Yangling, 712100 Shaanxi, China.
The aluminum in acid soils is very rhizotoxic to most plant species, but it is essential for root growth and development in Camellia sinensis. However, the molecular basis of Al-mediated signaling pathways in root regeneration of tea plants is largely unclear. In this study, we profiled the physiological phenotype, transcriptome, and phytohormones in the process using stems treated with Al (0.3 mM) and control (0.02 mM). The anatomical analysis showed that the 0.3 mM Al-treated stem began to develop adventitious root (AR) primordia within 7 days, ARs occurred after 21 days, while the control showed a significant delay. We further found that the expression patterns of many genes involved in the biosynthesis of ZT, ACC, and JA were stimulated by Al on day 3; also, the expression profiles of auxin transporter-related genes were markedly increased under Al during the whole rooting process. Moreover, the expression of these genes was strongly correlated with the accumulation of ZT, ACC, JA, and IAA. CsERFs, CsMYBs, and CsWRKYs transcription factor genes with possible crucial roles in regulating AR regeneration were also uncovered. Our findings suggest that multiple phytohormones and genes related to their biosynthesis form a hierarchical transcriptional cascade during Al-induced de novo root regeneration in tea nodal cuttings.
PMID: 34018729
Plant Cell Physiol , IF:4.062 , 2021 May doi: 10.1093/pcp/pcab061
Knockdown of Succinate Dehydrogenase Assembly Factor 2 Induces Reactive Oxygen Species-Mediated Auxin Hypersensitivity Causing pH-dependent Root Elongation.
ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia.; School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia.; Department of Animal, Plant and Soil Sciences, School of Life Science, ARC Centre of Excellence in Plant Energy Biology, La Trobe University, Bundoora, VIC, 3083, Australia.
Metabolism, auxin signalling and ROS all contribute to plant growth and each is linked to plant mitochondria and the process of respiration. Knockdown of mitochondrial Succinate Dehydrogenase Assembly Factor 2 (SDHAF2) in Arabidopsis thaliana, lowered succinate dehydrogenase activity and led to pH-inducible root inhibition when the growth medium pH was poised at different points between 7.0 and 5.0, but this phenomenon was not observed in WT. Roots of sdhaf2 mutants showed high accumulation of succinate, depletion of citrate and malate and up-regulation of ROS-related and stress-inducible genes at pH 5.5. A change of oxidative status in sdhaf2 roots at low pH was also evidenced by low ROS staining in root tips and altered root sensitivity to H2O2. sdhaf2 had low auxin activity in root tips via DR5-GUS staining, but displayed increased IAA (auxin) abundance and IAA hypersensitivity, which is most likely caused by the change in ROS levels. On this basis we conclude that knockdown of SDHAF2 induces pH-related root elongation and auxin hyperaccumulation and hypersensitivity, mediated by altered ROS homeostasis. This observation extends the existing evidence of associations between mitochondrial function and auxin by establishing a cascade of cellular events that link them through ROS formation, metabolism and root growth at different pH values.
PMID: 34018557
Sci Rep , IF:3.998 , 2021 May , V11 (1) : P9870 doi: 10.1038/s41598-021-88971-5
Light quality and quantity affect graft union formation of tomato plants.
College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.; Department of Horticulture, College of Agriculture, University of Al-Azhar (Branch Assiut), Assiut, 71524, Egypt.; Plant Pathology Department, Faculty of Agriculture, Alexandria University, El-Shatby, Alexandria, 21545, Egypt.; Department of Plant Physiology, Institute of Biology, Warsaw, University of Life Sciences SGGW, 159 Nowoursynowska 159, 02-776, Warsaw, Poland.; Department of Bioengineering, West Pomeranian University of Technology in Szczecin, 17 Slowackiego Street, 71-434, Szczecin, Poland.; College of Mechanical and Electronic Engineering, Fujian Agriculture and Forestry University, Fuzhou, 350002, China. y.xu@fafu.edu.cn.; Institute of Machine Learning and Intelligent Science, Fujian University of Technology, 33 Xuefu South Road, Fuzhou, 350118, China. y.xu@fafu.edu.cn.; College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China. cfaxing@126.com.
It is already known that there are many factors responsible for the successful formation of a graft union. However, the role of light has been little studied. In an anatomical study, Scanning Electronic Microscope (SEM) was used to explore the effects of different light-emitting diodes (LEDs) on graft union formation in grafted tomato. In addition, the expression genes related to Auxin hormone signaling pathway (SAUR67, AUX1, ARF30, and LAX3) was investigated. The obtained results showed that the concrescence process occurred faster under R7:B3 light conditions, as compared to blue (B) and white fluorescent (WFL) lights. Red light application caused a delay in the vascular tissue differentiation, which may lead to callus development on both sides, causing junctional failure and resulting in ineffective graft junctional arrangement. The expression of genes related to Auxin hormone significantly increased by R7:B3 application. We suggest that LED spectra affects the graft development of tomato plants and can improve the performance of grafted tomato seedlings.
PMID: 33972562
Sci Rep , IF:3.998 , 2021 May , V11 (1) : P9688 doi: 10.1038/s41598-021-88874-5
ATHB2 is a negative regulator of germination in Arabidopsis thaliana seeds.
Consejo Nacional de Investigaciones Cientificas y Tecnicas, Instituto de Investigaciones Fisiologicas y Ecologicas Vinculadas a la Agricultura (IFEVA), Facultad de Agronomia, Universidad de Buenos Aires, Av. San Martin 4453, C1417DSE, Buenos Aires, Argentina. rtognacca@agro.uba.ar.; Consejo Nacional de Investigaciones Cientificas y Tecnicas, Instituto de Fisiologia, Biologia Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CP1428, Buenos Aires, Argentina. rtognacca@agro.uba.ar.; Institute of Molecular Biology and Pathology, National Research Council, P.le A. Moro 5, 00185, Rome, Italy.; Research Centre for Genomics and Bioinformatics, Council for Agricultural Research and Economics (CREA), Via Ardeatina 546, 00178, Rome, Italy.; Consejo Nacional de Investigaciones Cientificas y Tecnicas, Instituto de Investigaciones Fisiologicas y Ecologicas Vinculadas a la Agricultura (IFEVA), Facultad de Agronomia, Universidad de Buenos Aires, Av. San Martin 4453, C1417DSE, Buenos Aires, Argentina.
The germination timing of seeds is of the utmost adaptive importance for plant populations. Light is one of the best characterized factors promoting seed germination in several species. The germination is also finely regulated by changes in hormones levels, mainly those of gibberellin (GA) and abscisic acid (ABA). Here, we performed physiological, pharmacological, and molecular analyses to uncover the role of ATHB2, an HD-ZIP II transcription factor, in germination of Arabidopsis seeds. Our study demonstrated that ATHB2 is a negative regulator and sustains the expression of transcription factors to block germination promoted by light. Besides, we found that ATHB2 increases ABA sensitivity. Moreover, ABA and auxin content in athb2-2 mutant is higher than wild-type in dry seeds, but the differences disappeared during the imbibition in darkness and the first hours of exposition to light, respectively. Some ABA and light transcription factors are up-regulated by ATHB2, such as ABI5, ABI3, XERICO, SOMNUS and PIL5/PIF1. In opposition, PIN7, an auxin transport, is down-regulated. The role of ATHB2 as a repressor of germination induced by light affecting the gemination timing, could have differential effects on the establishment of seedlings altering the competitiveness between crops and weeds in the field.
PMID: 33958633
Sci Rep , IF:3.998 , 2021 May , V11 (1) : P9739 doi: 10.1038/s41598-021-87722-w
Comprehensive molecular dissection of TIFY Transcription factors reveal their dynamic responses to biotic and abiotic stress in wheat (Triticum aestivum L.).
Department of Bio-Engineering, Birla Institute of Technology, Mesra, Ranchi, 835215, Jharkhand, India.; Department of Bio-Engineering, Birla Institute of Technology, Mesra, Ranchi, 835215, Jharkhand, India. kmukhopadhyay@bitmesra.ac.in.
The plant specific TIFY (previously known as ZIM) transcription factor (TF) family plays crucial roles in cross talk between Jasmonic Acid and other phytohormones like gibberellins, salicylic acid, abscisic acid, auxin, and ethylene signaling pathways. Wheat yield is severely affected by rust diseases and many abiotic stresses, where different phytohormone signaling pathways are involved. TIFYs have been studied in many plants yet reports describing their molecular structure and function in wheat are lacking. In the present study, we have identified 23 novel TIFY genes in wheat genome using in silico approaches. The identified proteins were characterized based on their conserved domains and phylogenetically classified into nine subfamilies. Chromosomal localization of the identified TIFY genes showed arbitrary distribution. Forty cis-acting elements including phytohormone, stress and light receptive elements were detected in the upstream regions of TIFY genes. Seventeen wheat microRNAs targeted the identified wheat TIFY genes. Gene ontological studies revealed their major contribution in defense response and phytohormone signaling. Secondary structure of TIFY proteins displayed the characteristic alpha-alpha-beta fold. Synteny analyses indicated all wheat TIFY genes had orthologous sequences in sorghum, rice, maize, barley and Brachypodium indicating presence of similar TIFY domains in monocot plants. Six TIFY genes had been cloned from wheat genomic and cDNA. Sequence characterization revealed similar characteristics as the in silico identified novel TIFY genes. Tertiary structures predicted the active sites in these proteins to play critical roles in DNA binding. Expression profiling of TIFY genes showed their contribution during incompatible and compatible leaf rust infestation. TIFY genes were also highly expressed during the initial hours of phytohormone induced stress. This study furnishes fundamental information on characterization and putative functions of TIFY genes in wheat.
PMID: 33958607
Plant Reprod , IF:3.957 , 2021 May doi: 10.1007/s00497-021-00413-4
Conserved, divergent and heterochronic gene expression during Brachypodium and Arabidopsis embryo development.
Laboratory of Biochemistry, Wageningen University, Stippeneng 4, Wageningen, The Netherlands.; Key Laboratory of Forest Genetics & Biotechnology of Ministry of Education, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu, China.; Aquatic and Crop Resource Development, National Research Council Canada, Saskatoon, SK, Canada.; Department of Plant Sciences, College of Agriculture, University of Saskatchewan, Saskatoon, SK, Canada.; Global Institute for Food Security, University of Saskatchewan, Saskatoon, SK, Canada.; Laboratory of Biochemistry, Wageningen University, Stippeneng 4, Wageningen, The Netherlands. dolf.weijers@wur.nl.
KEY MESSAGE: Developmental and transcriptomic analysis of Brachypodium embryogenesis and comparison with Arabidopsis identifies conserved and divergent phases of embryogenesis and reveals widespread heterochrony of developmental gene expression. Embryogenesis, transforming the zygote into the mature embryo, represents a fundamental process for all flowering plants. Current knowledge of cell specification and differentiation during plant embryogenesis is largely based on studies of the dicot model plant Arabidopsis thaliana. However, the major crops are monocots and the transcriptional programs associated with the differentiation processes during embryogenesis in this clade were largely unknown. Here, we combined analysis of cell division patterns with development of a temporal transcriptomic resource during embryogenesis of the monocot model plant Brachypodium distachyon. We found that early divisions of the Brachypodium embryo were highly regular, while later stages were marked by less stereotypic patterns. Comparative transcriptomic analysis between Brachypodium and Arabidopsis revealed that early and late embryogenesis shared a common transcriptional program, whereas mid-embryogenesis was divergent between species. Analysis of orthology groups revealed widespread heterochronic expression of potential developmental regulators between the species. Interestingly, Brachypodium genes tend to be expressed at earlier stages than Arabidopsis counterparts, which suggests that embryo patterning may occur early during Brachypodium embryogenesis. Detailed investigation of auxin-related genes shows that the capacity to synthesize, transport and respond to auxin is established early in the embryo. However, while early PIN1 polarity could be confirmed, it is unclear if an active response is mounted. This study presents a resource for studying Brachypodium and grass embryogenesis and shows that divergent angiosperms share a conserved genetic program that is marked by heterochronic gene expression.
PMID: 33950292
Plant Genome , IF:3.847 , 2021 May : Pe20099 doi: 10.1002/tpg2.20099
The effects of crop attributes, selection, and recombination on Canadian bread wheat molecular variation.
Department of Plant Agriculture, University of Guelph, Crop Science Building, 50 Stone Road E, Guelph, ON, N1G 2W1, Canada.; Department of Plant Sciences and Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8, Canada.; Grain Research Laboratory, Canadian Grain Commission, 196 Innovation Drive, Winnipeg, MB, R3T 6C5, Canada.
Cultivated germplasm provides an opportunity to investigate how crop agronomic traits, selection for major genes, and differences in crossing-over rates drive patterns of allelic variation. To identify how these factors correlated with allelic variation within a collection of cultivated bread wheat (Triticum aestivum L.), we generated genotypes for 388 accessions grown in Canada over the past 170 yr using filtered single nucleotide polymorphism (SNP) calls from an Illumina Wheat iSelect 90K SNP-array. Entries' breeding program, era of release, grain texture, kernel color, and growth habit contributed to allelic differentiation. Allelic diversity and linkage disequilibrium (LD) of markers flanking some major loci known to affect traits such as gluten strength, growth habit, and grain color were consistent with selective sweeps. Nonetheless, some flanking markers of major loci had low LD and high allelic diversity. Positive selection may have acted upon homoeologous genes that had significant enrichment for the gene ontology terms 'response-to-auxin' and 'response-to-wounding.' Long regions of LD, spanning approximately one-third the length of entire chromosomes, were associated with many pericentromeric regions. These regions were also characterized by low diversity. Enhancing recombination across these regions could generate novel allele combinations to accelerate Canadian wheat improvement.
PMID: 34009734
Plant Physiol Biochem , IF:3.72 , 2021 May , V165 : P123-136 doi: 10.1016/j.plaphy.2021.05.015
Transcriptome analysis reveals the promotive effect of potassium by hormones and sugar signaling pathways during adventitious roots formation in the apple rootstock.
College of Horticulture, Yangling Subsidiary Center Project of the National Apple Improvement Center, Northwest Agriculture & Forestry University, Yangling, 712100, China.; College of Agriculture, The Key Laboratory of Special Fruits and Vegetables Cultivation Physiology and Germplasm Resources Utilization in Xinjiang Production and Construction Group, Shihezi University, 832003, Shihezi, Xinjiang, China.; College of Horticulture, Yangling Subsidiary Center Project of the National Apple Improvement Center, Northwest Agriculture & Forestry University, Yangling, 712100, China. Electronic address: baolu@nwsuaf.edu.cn.; College of Horticulture, Yangling Subsidiary Center Project of the National Apple Improvement Center, Northwest Agriculture & Forestry University, Yangling, 712100, China. Electronic address: afant@nwsuaf.edu.cn.
Apples are economically valuable and widely consumed fruits. The adventitious roots (ARs) formation is gridlock for apple trees mass propagation. The possible function of multiple hormones and sugar signaling pathways regulating ARs formation has not been completely understood in apple. In this study, B9 stem cuttings were treated with KCl treatment, where the highest root numbers (220) and maximum root length of 731.2 cm were noticed in KCl-treated cuttings, which were 98.2% and 215% higher than control cuttings. The content of endogenous hormones: IAA, ZR, JA, GA, and ABA were detected higher in response to KCl at most time-points. To figure out the molecular mechanisms underlying this effect, we investigated transcriptome analysis. In total, 4631 DEGs were determined, from which about 202 DEGs were considerably enriched in pathways associated with hormone signaling, sugar metabolism, root development, and cell cycle-related and were thereupon picked out on their potential involvements in ARs formation. Though, IAA accumulation and up-regulation of various genes contribute to induce AR formation. These results suggest that AR formation is a complex biological process in apple rootstocks, influenced mainly by the auxin signaling pathway and sugar metabolism.
PMID: 34038809
Plant Physiol Biochem , IF:3.72 , 2021 May , V165 : P10-18 doi: 10.1016/j.plaphy.2021.04.037
Agrobacterium rhizogenes rolB oncogene: An intriguing player for many roles.
Dipartimento di Biologia e Biotecnologie, Sapienza Universita di Roma, P.le Aldo Moro 5, 00185, Roma, Italy. Electronic address: marialuisa.mauro@fondazione.uniroma1.it.; Dipartimento di Biologia, Universita degli Studi di Firenze, via Madonna del Piano 6, 50019, Sesto f.no, FI, Italy. Electronic address: p.bettini@unifi.it.
The rolB oncogene is one of the so-called rol genes found in the T-DNA region of the Agrobacterium rhizogenes Ri plasmid and involved in the hairy root syndrome, a tumour characterized by adventitious root overgrowth on plant stem. rolB produces in plants a peculiar phenotype that, together with its root-inducing capacity, has been connected to auxin sensitivity. The gene is able to modify the plant genetic programme to induce meristem cells and direct them to differentiate not only roots, but also other cells, tissues or organs. Besides its essential function in hairy root pathogenesis, the rolB role has been progressively extended to cover several physiological aspects in the transgenic plants: from secondary metabolites production and ROS inhibition, to abiotic and biotic stress tolerance and photosynthesis improvement. Some of the observed effects could be determined, at least in part, through microRNAs molecules, suggesting an epigenetic control rolB-mediated. These multifaceted capacities could allow plants to withstand adverse environmental conditions, enhancing fitness. In spite of this expanding knowledge, functional analyses did not detect yet any definitive rolB-derived biochemical product, even if more than one enzymatic activity has been ascribed to it. Moreover, phylogenetic and evolutionary studies evidenced no homology with any plant sequences but, otherwise, it belongs to the Plast family, a group of rolB-homologous bacterial genes. Finally, the finding of sequences similar to rolB in plants not infected by A. rhizogenes suggests a hypothetical plant origin for this gene, implying different possibilities about its evolution.
PMID: 34029941
GM Crops Food , IF:3.444 , 2021 May : P1-22 doi: 10.1080/21645698.2021.1917975
Exploring potential of copper and silver nano particles to establish efficient callogenesis and regeneration system for wheat (Triticum aestivum L.).
Chinese Academy Of Agricultural Sciences, State Key Laboratory Cotton Research Institute, Anyang, Henan, China.; Department of Agronomy, PMAS Arid Agriculture University, Rawalpindi, Pakistan.; Department of Botany, University of Gujrat, Gujrat, Pakistan.; Department of agronomy, Farmland Irrigation Research Institute of CAAS, Xinxiang, Henan, China.; Department of Plant Breeding and Genetics, Nuclear Institute for Agriculture and Biology, Faisalabad, Pakistan.; Centre for Climate Research and Development, COMSATS University, Islamabad, Pakistan.; Climate Resilience Department, Asian Disaster Preparedness Center (ADPC), Islamabad, Pakistan.
In vitro recalcitrance of wheat to regeneration is the major bottleneck for its improvement through callus-based genetic transformation. Nanotechnology is one of the most dynamic areas of research, which can transform agriculture and biotechnology to ensure food security on sustainable basis. Present study was designed to investigate effects of CuSO4, AgNO3 and their nanoparticles on tissue culture responses of mature embryo culture of wheat genotypes (AS-2002 and Wafaq-2001). Initially, MS-based callus induction and regeneration medium were optimized for both genotypes using various concentrations of auxin (2,4-D, IAA) and cytokinins (BAP, kinetin). The genotypes differed for embryogenic callus induction and regeneration potential. Genotype AS-2002 yielded maximum embryogenic calli in response to 3.0 mg/l 2,4-D, whereas Wafaq-2001 offered the highest embryogenic calli against 3.5 mg/l 2,4-D supplemented in the induction medium. Genotype AS-2002 showed maximum regeneration (59.33%) in response to regeneration protocol comprising 0.5 mg/l IAA, 0.3 mg/l BAP and 1.0 mg/l Kin, while Wafaq-2001 performed best in response to 0.5 mg/l IAA, 0.3 mg/l BAP and 1.5 mg/l Kin with 55.33% regeneration efficiency. The same optimized basal induction and regeneration medium for both genotypes were further used to study effects of CuSO4, AgNO3 and their nano-particles employing independent experiments. The optimized induction medium fortified with various concentrations of CuSO4 or CuNPs confirmed significant effects on frequency of embryogenic callus. Addition of either 0.020 mg/l or 0.025 mg/l CuSO4, or 0.015 mg/l CNPs showed comparable results for embryogenic callus induction and were statistically at par with embryogenic callus induction of 74.00%, 75.67% and 76.83%, respectively. Significantly higher regeneration was achieved from MS-based regeneration medium supplemented with 0.015 mg/l or 0.020 mg/l CuNPs than standard 0.025 mg/l CuSO4. In another study, the basal induction and regeneration medium were fortified with AgNO3 or AgNPs ranging from 1 to 7 mg/l along with basal regeneration media devoid of AgNO3 or AgNPs (control). The maximum embryogenic calli were witnessed from medium fortified with 3.0 mg/l or 4.0 mg/l AgNPs compared with control and rest of the treatments. The standardized regeneration medium fortified with 5.0 mg/l AgNO3 or 3.0 mg/l AgNPs showed pronounced effect on regeneration of wheat genotypes and offered maximum regeneration compared with control. The individual and combined effect of Cu and Ag nanoparticles along with control (basal regeneration media of each genotype) was also tested. Surprisingly, co-application of metallic NPs showed a significant increase in embryogenic callus formation of genotypes. Induction medium supplemented with 0.015 mg/l CuNPs + 4.0 mg/l AgNPs or 0.020 mg/l CuNPs + 2.0 mg/l AgNPs showed splendid results compared to control and other combination of Cu and Ag nanoparticles. The maximum regeneration was achieved by co-application of 0.015 mg/l CuNP and 4.0 mg/l AgNPs with 21% increment of regeneration over control. It is revealed that CuNPs and AgNPs are potential candidate to augment somatic embryogenesis and regeneration of mature embryo explants of wheat.
PMID: 33938377
Planta , IF:3.39 , 2021 May , V253 (6) : P128 doi: 10.1007/s00425-021-03644-x
Analysis of unigenes involved in lateral root development in Bupleurum chinense and B. scorzonerifolium.
School of Life Science and Engineering, Southwest University of Science and Technology, 59 Qinglong Road, Mianyang, 621010, Sichuan, China.; Laboratory of Medicinal Plant Cultivation, Institute of Medicinal Plant Development (IMPLAD), Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China.; Yibin Inspection and Testing Centre for Food and Medicine, Yibin, 644000, Sichuan, China.; Africa Rice Center (AfricaRice), M'be Research Station, 01 B.P. 2551, Bouake, Cote d'Ivoire.; Institute of Biomass Energy, Neijiang Academy of Agricultural Sciences of Sichuan Province, 401 Huayuantan Road, Neijiang, 641000, Sichuan, China.; School of Life Science and Engineering, Southwest University of Science and Technology, 59 Qinglong Road, Mianyang, 621010, Sichuan, China. yuwen0073@126.com.; Laboratory of Medicinal Plant Cultivation, Institute of Medicinal Plant Development (IMPLAD), Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193, China. jhwei@implad.ac.cn.
MAIN CONCLUSION: We identified IAA13 negatively associated with lateral root number by comparing the differential expressed genes between Bupleurum chinense and B. scorzonerifolium. Dried roots of the genus Bupleurum L. are used as a herbal medicine for diseases in Asia. Bupleurum chinense has a greater number of lateral roots than B. scorzonerifolium, but the genetic mechanisms for such differences are largely unknown. We (a) compared the transcriptome profiles of the two species and (b) identified a subset of candidate genes involved in auxin signal transduction and explored their functions in lateral root development. By isoform sequencing (Iso-Seq) analyses of the whole plant, more unigenes were found in B. scorzonerifolium (118,868) than in B. chinense (93,485). Given the overarching role of indole-3-acetic acid (IAA) as one of the major regulators of lateral root development, we identified 539 unigenes associated with auxin signal transduction. Fourteen and 44 unigenes in the pathway were differentially expressed in B. chinense and B. scorzonerifolium, respectively, and 3 unigenes (LAX2, LAX4, and IAA13) were expressed in both species. The number of lateral root primordia increased after exogenous auxin application at 8 h and 12 h in B. scorzonerifolium and B. chinense, respectively. Since overexpression of IAA13 in Arabidopsis reduced the number of lateral roots, we hypothesized that IAA13 is involved in the reduction of the number of lateral roots in B. scorzonerifolium.
PMID: 34037846
Planta , IF:3.39 , 2021 May , V253 (6) : P123 doi: 10.1007/s00425-021-03640-1
Strigolactone signaling inhibition increases adventitious shoot formation on internodal segments of ipecac.
Graduate School of Life Sciences, Toyo University, 1-1-1 Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan.; Department of Applied Biosciences, Toyo University, 1-1-1 Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan.; Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo, 156-8502, Japan.; Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657, Japan.; Graduate School of Life Sciences, Toyo University, 1-1-1 Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan. umehara@toyo.jp.; Department of Applied Biosciences, Toyo University, 1-1-1 Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan. umehara@toyo.jp.
MAIN CONCLUSION: SL inhibited adventitious shoot formation of ipecac, whereas the SL-related inhibitors promoted adventitious shoot formation. SL-related inhibitors might be useful as new plant growth regulators for plant propagation. In most plant species, phytohormones are required to induce adventitious shoots for propagating economically important crops and regenerating transgenic plants. In ipecac (Carapichea ipecacuanha (Brot.) L. Andersson), however, adventitious shoots can be formed without phytohormone treatment. Here we evaluated the effects of GR24 (a synthetic strigolactone, SL), SL biosynthetic inhibitors, and an SL antagonist on adventitious shoot formation during tissue culture of ipecac. We found that exogenously applied GR24 suppressed indole-3-acetic acid transport in internodal segments and decreased the number of adventitious shoots formed; in addition, the distribution of adventitious shoots changed from the apical to middle region of the internodal segments. In contrast, the SL-related inhibitors promoted adventitious shoot formation on both apical and middle regions of the segments. In particular, SL antagonist treatment increased endogenous cytokinin levels and induced multiple shoot development. These results indicate that SL inhibits adventitious shoot formation in ipecac. In ipecac, one of the shoots in each internodal segment becomes dominant and auxin derived from that shoot suppresses the other shoot growth. Here, this dominance was overcome by application of SL-related inhibitors. Therefore, SL-related inhibitors might be useful as new plant growth regulators to improve the efficiency of plant propagation in vitro.
PMID: 34014387
J Plant Physiol , IF:3.013 , 2021 May , V262 : P153437 doi: 10.1016/j.jplph.2021.153437
Interactive effects of plant growth-promoting rhizobacteria and a seaweed extract on the growth and physiology of Allium cepa L. (onion).
Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa.; Laboratory of Growth Regulators, Faculty of Science, Palacky University & Institute of Experimental Botany AS CR, v.v.i., Slechtitelu 11, 78371, Olomouc, Czech Republic.; Laboratory of Growth Regulators, Faculty of Science, Palacky University & Institute of Experimental Botany AS CR, v.v.i., Slechtitelu 11, 78371, Olomouc, Czech Republic; Department of Chemical Biology, Faculty of Science, Palacky University, Slechtitelu 11, 78371, Olomouc, Czech Republic.; Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa. Electronic address: rcpgd@ukzn.ac.za.
Detrimental effects caused by the overuse of synthetic agrochemicals have led to the development of natural biostimulants such as seaweed extracts and plant growth-promoting rhizobacteria (PGPR) being used as an alternative, environmentally-friendly technology to improve crop growth and increase agricultural yields. The present study aimed to investigate the interactions between PGPR and a commercial seaweed extract on the growth and biochemical composition of onion (Allium cepa). A pot trial was conducted under greenhouse conditions where onion plants were treated individually with the two PGPR, namely Bacillus licheniformis (BL) and Pseudomonas fluorescens (PF) and a seaweed extract Kelpak(R) (KEL) and combinations of KEL+BL and KEL+PF. Growth and yield parameters were measured after 12 weeks. KEL-treated plants showed the best growth response and overcame the inhibitory effects of BL treatment. KEL-treated plants also had the highest chlorophyll content. PGPR application improved the mineral nutrition of onion with these plants having the highest mineral content in the leaves and bulb. All biostimulant treatments increased the endogenous cytokinin and auxin content with the highest concentrations generally detected in the PF-treated plants. These results suggest that co-application of different biostimulant classes with different modes of action could further increase crop productivity with an improvement in both growth and nutrition content being achieved in onion with the co-application of a seaweed extract and PGPR.
PMID: 34034041
J Plant Physiol , IF:3.013 , 2021 May , V262 : P153436 doi: 10.1016/j.jplph.2021.153436
Extracting relevant physiological information from polar auxin transport data in Panax ginseng.
Plant Biodynamics Laboratory, Institute of Biology, Leiden University, 2333 BE, Leiden, the Netherlands; Fytagoras, 2333 BE, Leiden, the Netherlands.; Plant Biodynamics Laboratory, Institute of Biology, Leiden University, 2333 BE, Leiden, the Netherlands; Mathematical Institute, Leiden University, 2333 CA, Leiden, the Netherlands.; Fytagoras, 2333 BE, Leiden, the Netherlands.; Plant Biodynamics Laboratory, Institute of Biology, Leiden University, 2333 BE, Leiden, the Netherlands.; Plant Biodynamics Laboratory, Institute of Biology, Leiden University, 2333 BE, Leiden, the Netherlands; Fytagoras, 2333 BE, Leiden, the Netherlands. Electronic address: bert.vanduijn@fytagoras.com.
BACKGROUND: Measuring polar auxin transport (PAT) in plants and drawing conclusions from the observed transport data is only meaningful if these data are being analysed with a mathematical model which describes PAT. In this report we studied the polar auxin transport in Panax ginseng stems of different age and grown on different substrates. METHODS: We measured polar IAA transport in stems using a radio labelled IAA and analysed the transport data with a mathematical model we developed for Arabidopsis. RESULTS: We found that PAT in ginseng stems, as compared to Arabidopsis inflorescence stems, has a 2-fold lower transport velocity and a 3-fold lower steady state auxin flux. CONCLUSION: We were able to pinpoint two physiological parameters that influenced the observed transport characteristics in ginseng which differ from Arabidopsis, namely an increase in immobilization together with a reduced reflux of IAA from the surrounding tissue back to the transporting cells.
PMID: 34029983
Biochem Biophys Res Commun , IF:2.985 , 2021 May , V553 : P44-50 doi: 10.1016/j.bbrc.2021.03.006
Arabidopsis SMAX1 overaccumulation suppresses rosette shoot branching and promotes leaf and petiole elongation.
Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.; Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China. Electronic address: xinlisun@fafu.edu.cn.
ARABIDOPSIS: SMAX1/SMXL (SUPPRESSOR OF MAX2 1/SMAX1-LIKE) proteins function as transcriptional repressors in karrikin and strigolactone (SL) signaling pathways and regulate plant architecture. MAX2 is a common factor in the two signaling pathways and a component of the SCF complex that modulates the proteasome-mediated degradation of SMAX1/SMXLs. SMXL6, 7, and 8 proteins promote shoot branching and inhibit petiole elongation. Our study found that the accumulation of SMAX1 suppresses rosette shoot branching and increases cauline branches on the primary inflorescence stem, plant height, petiole length, and leaf length/width ratio. The SMAX1 accumulation enhances the expression of BRC1, HB53, HB40, and HB21 that modulate shoot branching. SMAX1 also regulates the expression of the genes involved in auxin transport, cytokinin signaling pathway, and SL biosynthesis. The expression analyses of these genes suggest that excessive SMAX1 should accelerate the transport of auxin and the biosynthesis of SL in plants. High SL concentration suppresses the bud development in smax1D mutant that accumulates SMAX1 protein in plant. However, the effects of cytokinin and auxin on shoot branching remain elusive in the mutant with excessive SMAX1. SMAX1 regulates leaf shape and petiole length via modulating TCP1 expression. Our findings reveal a novel function of SMAX1 and new mechanism of shoot branching.
PMID: 33756344
Photochem Photobiol , IF:2.721 , 2021 May doi: 10.1111/php.13441
Role of Light and Plant Hormones in Stem Parasitic Plant (Cuscuta and Cassytha) Twining and Haustoria Induction.
Department of Parasitic Plant Physiology, Maeda-Institute of Plant Resources, Nagoya, Japan.; Department of Natural and Environmental Science, Teikyo University of Science, Tokyo, Japan.; Anicom Specialty Medical Institute Inc, Tokyo, Japan.
Cuscuta and Cassytha are two distinct stem parasitic plant genera developing haustoria at their stem. The initial step to parasitization is twining onto the host plant. Although twining is the critical first step, less attention has been paid to this aspect in stem haustoria parasitic plant studies. As tendril coiling is also controlled by light and plant hormones, we investigated the role of light (blue, red and far-red) and hormones (auxin, brassinolide, cytokinin) in twining of stem parasitic plants (Cuscuta japonica and Cassytha filiformis). In general, both Cuscuta and Cassytha showed similar behavior to light cues. The data show that blue light is essential for twining, and a lower far-red/red light (FR/R) ratio is important for subsequent haustoria induction. Regarding plant hormones, seedlings with solely auxin or cytokinin (iP) under blue light showed not only twining but also haustoria induction, demonstrating that auxin and iP appear to be especially important for induction. Seedlings with solely brassinolide showed no positive influence, but brassinolide together with iP caused twining even under dark conditions. This points to the presence of cross-talk between brassinolide and cytokinin for twining.
PMID: 33934364
Bioorg Med Chem Lett , IF:2.572 , 2021 May , V43 : P128085 doi: 10.1016/j.bmcl.2021.128085
Tryptophan derivatives regulate the seed germination and radicle growth of a root parasitic plant, Orobanche minor.
Department of Agricultural Chemistry, School of Agriculture, Meiji University, 1-1-1 Higashi-mita, Tama-ku, Kawasaki-shi, Kanagawa 214-8571, Japan.; Department of Agricultural Chemistry, School of Agriculture, Meiji University, 1-1-1 Higashi-mita, Tama-ku, Kawasaki-shi, Kanagawa 214-8571, Japan. Electronic address: yoshiya@meiji.ac.jp.
Root parasitic plant germination is induced by the host-derived chemical, strigolactone (SL). We found that a major microbial culture broth component, tryptone, inhibits the SL-inducible germination of a root parasitic plant, Orobanche minor. l-tryptophan (l-Trp) was isolated as the active compound from tryptone. We further found that l-Trp related compounds (1b-11), such as a major plant hormone auxin (8, indole-3-acetic acid; IAA), also inhibit the germination and post-radicle growth of O. minor. We designed a hybrid chemical (13), in which IAA is attached to a part of SL, and found that this synthetic analog induced the germination of O. minor, and also inhibited post-radicle growth. Moreover, contrary to our expectations, we found that N-acetyl Trp (9) showed germination stimulating activity, and introduction of a substitution at C-5 position increased its activity (12a-12f). Our data, in particular, the discovery of a structurally hybrid compound that has two activities that induce spontaneous germination and inhibit subsequent radical growth, would provide new types of germination regulators for root parasitic plants.
PMID: 33964445
Arch Microbiol , IF:1.884 , 2021 May doi: 10.1007/s00203-021-02361-z
The auxin-producing Bacillus thuringiensis RZ2MS9 promotes the growth and modifies the root architecture of tomato (Solanum lycopersicum cv. Micro-Tom).
Department of Genetics, Luiz de Queiroz College of Agriculture, University of Sao Paulo, 11 Padua Dias Av., Piracicaba, SP, 13418-900, Brazil.; Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia.; Department of Microbiology, Biomedicine Institute, University of Sao Paulo, Sao Paulo, SP, Brazil.; Laboratory of Nuclear Instrumentation, Center of Nuclear Energy in Agriculture, University of Sao Paulo, Piracicaba, SP, Brazil.; Department of Crop Science, Luiz de Queiroz College of Agriculture, University of Sao Paulo, Piracicaba, SP, Brazil.; Bioinformatics Core, University of California, Davis, CA, USA.; Department of Genetics, Luiz de Queiroz College of Agriculture, University of Sao Paulo, 11 Padua Dias Av., Piracicaba, SP, 13418-900, Brazil. mquecine@usp.br.
Strains of Bacillus thuringiensis (Bt) are commonly commercialized as bioinoculants for insect pest control, but their benefits go beyond their insecticidal property: they can act as plant growth-promoters. Auxins play a major role in the plant growth promotion. However, the mechanism of auxin production by the Bacilli group, and more specifically by Bt strains, is unclear. In previous work, the plant growth-promoting rhizobacterium (PGPR) B. thuringiensis strain RZ2MS9 increased the corn roots. This drew our attention to the strain's auxin production trait, earlier detected in vitro. Here, we demonstrate that in its genome, RZ2MS9 harbours the complete set of genes required in two pathways that are used for Indole acetic acid (IAA) production. We also detected that the strain produces almost five times more IAA during the stationary phase. The bacterial application increased the shoot dry weight of the Micro-Tom (MT) tomato by 24%. The application also modified MT root architecture, with an increase of 26% in the average lateral root length and inhibition of the axial root. At the cellular level, RZ2MS9-treated MT plants presented elongated root cortical cells with intensified mitotic activity. Altogether, these are the best characterized auxin-associated phenotypes. Besides that, no growth alteration was detected in the auxin-insensitive diageotropic (dgt) plants either with or without the RZ2MS9 inoculation. Our results suggest that auxins play an important role in the ability of B. thuringiensis RZ2MS9 to promote MT growth and provide a better understanding of the auxin production mechanism by a Bt strain.
PMID: 34013419
Plant Signal Behav , IF:1.671 , 2021 May : P1930442 doi: 10.1080/15592324.2021.1930442
Molecular cloning and expression analysis of a WRKY transcription factor gene, GbWRKY20, from Ginkgo biloba.
Co-Innovation Center for Sustainable Forestry in Southern China; College of Forestry, Nanjing Forestry University, Nanjing, China.
WRKY transcription factors are important regulators of diverse plant life processes. Our aim was to clone and characterize GbWRKY20, a WRKY gene of group IIc, derived from Ginkgo biloba. The cDNA sequence of GbWRKY20 was 818 bp long, encoding a 271-amino acid proteins and containing two introns and three exons. The proteinic molecular weight was 30.99 kDa, with a relevant theoretical isoelectric point of 8.15. Subcellular localization analysis confirmed that the GbWRKY20 protein localized to the nucleus. In total, 75 cis-regulatory elements of 19 different types were identified in the GbWRKY20 promoter sequence, including some elements involved in light responsiveness, anaerobic induction and circadian control, low-temperature responsiveness, as well as salicylic acid (SA) and auxin responsiveness. Expression pattern analysis of plant samples from different developmental stages and tissue types, revealed differential GbWRKY20 expression. The GbWRKY20 transcript was downregulated 12 h after heat treatment and at 4-12 h after drought treatment, but was upregulated 12 h after NaCl, cold and methyl jasmonate treatments. For abscisic acid and SA treatments, the GbWRKY20 transcript was upregulated at 24 h. In summary, GbWRKY20 encoded a newly cloned WRKY transcription factor of G. biloba that might be involved in plant growth and plant responses to abiotic stresses and hormones treatments.
PMID: 34024256
Plant Signal Behav , IF:1.671 , 2021 May : P1925440 doi: 10.1080/15592324.2021.1925440
Functions of long non-coding RNA in Arabidopsis thaliana.
CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.
A major part of the eukaryotic genome is transcribed into non-coding RNAs (ncRNAs) having no protein coding potential. ncRNAs which are longer than 200 nucleotides are categorized as long non coding RNAs (lncRNAs). Most lncRNAs are induced as a consequence of various environmental and developmental cues. Among plants, the functions of lncRNAs are best studied in Arabidopsis thaliana. In this review, we highlight the important functional roles of various lncRNAs during different stages of Arabidopsis life cycle and their response to environmental changes. These lncRNAs primarily govern processes such as flowering, seed germination, stress response, light- and auxin-regulated development, and RNA-dependent DNA methylation (RdDM). Major challenge is to differentiate between functional and cryptic transcripts. Genome editing, large scale RNAi and computational approaches may help to identify and characterize novel functional lncRNAs in Arabidopsis.
PMID: 33980126
Plant Signal Behav , IF:1.671 , 2021 May : P1926131 doi: 10.1080/15592324.2021.1926131
A dual mode of ethylene actions contributes to the optimization of hypocotyl growth under fluctuating temperature environments.
Department of Chemistry, Seoul National University, Seoul, Korea.; Plant Genomics and Breeding Institute, Seoul National University, Seoul, Korea.
The gaseous phytohormone ethylene plays versatile roles in sustaining plant growth and fitness in response to environmental changes, such as light illumination, flooding, and mechanical pressure. Interestingly, it is well known that the effects of ethylene on plant growth vary profoundly, depending on external conditions. For example, light/dark conditions alter the directionality of ethylene action on hypocotyl growth. Similarly, a recent study has shown that the effects of ethylene on hypocotyl growth are reversed during temperature increases: ethylene attenuates hypocotyl elongation in the light at warm temperatures (28 degrees C), while promoting it at normal temperatures (22 degrees C). The ethylene-activated ETHYLENE-INSENSITIVE 3 (EIN3) transcription factor directly promotes the transcription of both PHYTOCHROM INTERACTING FACTOR 3 (PIF3) and ARABIDOPSIS PP2C CLADE D7 (APD7) genes. At 22 degrees C, the auxin activity is tuned down, and thus ethylene promotes hypocotyl growth via the PIF3-mediated microtubule reorganization. On the other hand, when auxin highly accumulates at 28 degrees C, the ethylene-directed growth repression is potentiated through the APD7-mediated repression of auxin responses. APD7 plays a role in integrating ethylene cues into auxin signaling. We propose that the dual mode of EIN3-mediated ethylene actions enables plants to optimize growth under constantly changing environments.
PMID: 33975509
Plant Signal Behav , IF:1.671 , 2021 Jun , V16 (6) : P1907043 doi: 10.1080/15592324.2021.1907043
Exogenously-supplied trehalose inhibits the growth of wheat seedlings under high temperature by affecting plant hormone levels and cell cycle processes.
Instruments Sharing Platform of School of Life Sciences, East China Normal University, Shanghai, China.; Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, Department of Biology, Henan University, Kaifeng, China.; Stress Adaptation Research Unit, RIKEN Center for Sustainable Resource Science, Yokohama, Japan.
High temperature reduces the yield of crops, and exogenous trehalose can improve the stress resistance of plants. However, the mechanism by which trehalose causes phenotypic changes in plants is still unknown. Here we investigated the effects of exogenously supplied trehalose (1.5 mM) during high-temperature stress and subsequent recovery on plant hormones and cell cycle in wheat seedlings. Our results showed that after high-temperature stress, exogenously supplied trehalose reduced the root length, vertical height, leaf area, and leaf length of wheat seedlings, thereby reducing their growth. However, the content of hormones, such as abscisic acid, auxin (IAA), gibberellin (GA3), and cytokinin in seedlings pretreated with trehalose and high-temperature stress was lower than that under high-temperature stress alone. Our further experiments showed that the levels of these hormones were affected by genes involved in hormone biosynthesis and decomposition pathways in trehalose-pretreated seedlings. Compared with control plants, the activity of IAA oxidase is also higher. In addition, exogenous trehalose decreased the transcriptional levels of CycD2 and CDC2 (two genes regulating cell cycle progression) under heat stress, and reduced the activity of vacuolar invertase after recovery from heat stress, thereby shortening the cell length. These results indicate that trehalose inhibits wheat growth at high temperature by affecting plant hormone levels and the cell cycle process.AbbreviationsABA, abscisic acid; CDK, cyclin-dependent kinase; CycD, D-type cyclins; GA3, gibberellin; IAA, auxin; KRP, KIP-related protein; T6P, trehalsoe-6-phosphate; VIN, vacuolar invertase.
PMID: 33960273
Plant Signal Behav , IF:1.671 , 2021 May : P1913845 doi: 10.1080/15592324.2021.1913845
Virus-induced gene silencing (VIGS) analysis shows involvement of the LsSTPK gene in lettuce (Lactuca sativaL.) in high temperature-induced bolting.
Beijing Key Laboratory for Agricultural Application and New Technology, National Demonstration Center for Experimental Plant Production Education, College of Plant Science and Technology, Beijing University of Agriculture, Beijing, China.; University of Arizona, Tucson, Arizona, USA.
To determine the effect of the serine/threonine protein kinase (STPK) gene on leaf lettuce bolting, we utilized virus-induced gene silencing (VIGS) using the TRV vector to silence the target gene. The 'GB30' leaf lettuce cultivar was the test material, and the methods included gene cloning, bioinformatics analysis, quantitative real-time PCR (qRT-PCR) and VIGS. LsSTPK, was cloned from the 'GB30' leaf lettuce cultivar via reverse transcription-polymerase chain reaction (RT-PCR). qRT-PCR analysis showed that the expression of LsSTPK in the stem of leaf lettuce was significantly greater than that in the roots and leaves, and after high-temperature treatment, the gene expression in the stems in the experimental group was markedly lower than that in the control groups. Following LsSTPK silencing via the VIGS method, the stem length in the treatment group was significantly greater than that in the blank and negative control groups, and the contents of auxin (IAA), GA3 and abscisic acid (ABA) in the treatment group were greater than those in the other two groups. Flower bud differentiation occurred in the treatment group but not in the control group. The above findings suggested that LsSTPK inhibits the bolting of leaf lettuce under high-temperature conditions.
PMID: 33955335
Plant Signal Behav , IF:1.671 , 2021 May : P1920191 doi: 10.1080/15592324.2021.1920191
The lncRNA APOLO and the transcription factor WRKY42 target common cell wall EXTENSIN encoding genes to trigger root hair cell elongation.
Fundacion Instituto Leloir and IIBBA-CONICET, Buenos Aires, CP, Argentina.; Instituto de Agrobiotecnologia del Litoral, Universidad Nacional del Litoral, CONICET, FBCB/FHUC, Centro Cientifico Tecnologico CONICET Santa Fe, Paraje El Pozo, Santa Fe, Argentina.; Centro de Biotecnologia Vegetal (CBV), Facultad de Ciencias de la Vida (Fcsv), Universidad Andres Bello and Millennium Institute for Integrative Biology (Ibio), Santiago, Chile.
Plant long noncoding RNAs (lncRNAs) are key chromatin dynamics regulators, directing the transcriptional programs driving a wide variety of developmental outputs. Recently, we uncovered how the lncRNA AUXIN REGULATED PROMOTER LOOP (APOLO) directly recognizes the locus encoding the root hair (RH) master regulator ROOT HAIR DEFECTIVE 6 (RHD6) modulating its transcriptional activation and leading to low temperature-induced RH elongation. We further demonstrated that APOLO interacts with the transcription factor WRKY42 in a novel ribonucleoprotein complex shaping RHD6 epigenetic environment and integrating signals governing RH growth and development. In this work, we expand this model showing that APOLO is able to bind and positively control the expression of several cell wall EXTENSIN (EXT) encoding genes, including EXT3, a key regulator for RH growth. Interestingly, EXT3 emerged as a novel common target of APOLO and WRKY42. Furthermore, we showed that the ROS homeostasis-related gene NADPH OXIDASE C (NOXC) is deregulated upon APOLO overexpression, likely through the RHD6-RSL4 pathway, and that NOXC is required for low temperature-dependent enhancement of RH growth. Collectively, our results uncover an intricate regulatory network involving the APOLO/WRKY42 hub in the control of master and effector genes during RH development.
PMID: 33944666
Plant Signal Behav , IF:1.671 , 2021 May : P1922796 doi: 10.1080/15592324.2021.1922796
Vacuolar occupancy is crucial for cell elongation and growth regardless of the underlying mechanism.
Plant Pathology, University of Kaiserslautern, Kaiserslautern, Germany.
In the physiological range, the phytohormone auxin inhibits the growth of underground tissues. In the roots of Arabidopsis thaliana, cell size inhibition has been shown to be accompanied by auxin-mediated reduction of vacuole size. A tonoplast-localized protein family (Networked 4) with actin-binding capacity was demonstrated to modulate the compactness of the vacuole. Overexpression of NET4A led to smaller, more spherical and compact vacuoles, which occupied less cellular space compared to wild type. This reduction of vacuolar occupancy is similar to the observed auxin-induced decrease in occupancy, albeit there are enormous morphological differences. Here, we show that a net4a net4b double mutant and a NET4A overexpressor line are still sensitive to auxin-induced vacuolar constrictions. However, the overexpressor showed a partial auxin resistance accompanied by more compact vacuoles, thereby indicating an additional regulatory mechanism. Furthermore, we show that other NET superfamily members do not compensate for the loss of NET4A and NET4B expression on the transcriptional level. This leads us to hypothesize that regulation of vacuole size is a general mechanism to regulate cell expansion and that other players besides NET4 must participate in regulating the vacuole-cytoskeleton interface.
PMID: 33938395
Plant Signal Behav , IF:1.671 , 2021 May , V16 (5) : P1899488 doi: 10.1080/15592324.2021.1899488
Small compounds targeting tyrosine phosphorylation of Scaffold Protein Receptor for Activated C Kinase1A (RACK1A) regulate auxin mediated lateral root development in Arabidopsis.
Department of Biology, Howard University, Washington, USA.; Department of Biology, College of Science, University of Hafr Al Batin, Hafar Al Batin, Saudi Arabia.; Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, USA.; Department of Biochemistry and Molecular Biology, Georgetown University, Washington, USA.
Receptor for activated C kinase 1 (RACK1) is WD-40 type scaffold protein, conserved in all eukaryote organisms. Many reports implicated RACK1 in plant hormone signal transduction pathways including in auxin and diverse stress signaling pathways; however, the precise molecular mechanism of its role is not understood. Previously, a group of small compounds targeting the Arabidopsis RACK1A functional site-Tyr(248) have been developed. Here, the three different small compounds are used to elucidate the role of RACK1A in auxin mediated lateral root development. Through monitoring the auxin response in the architecture of lateral roots and auxin reporter assays, a small molecule- SD29-12 was found to stabilize the auxin induced RACK1A Tyr(248) phosphorylation, thereby stimulating auxin signaling and inducing lateral roots formation. In contrast, two other compounds, SD29 and SD29-14, inhibited auxin induced RACK1A Tyr(248) phosphorylation resulting in the inhibition of auxin sensitivity and alternation in the lateral roots formation. Taken together, auxin induced RACK1A Tyr(248) phosphorylation is found to be the critical regulatory mechanism for auxin-mediated lateral root development. This work leads to the molecular understanding of the role RACK1A plays in the auxin induced lateral root development signaling pathways. The auxin signal stimulating compound has the potential to be used as auxin-based root inducing bio-stimulant.
PMID: 33784940
Bull Environ Contam Toxicol , IF:1.657 , 2021 May doi: 10.1007/s00128-021-03254-z
Pesticide Mixtures in the Water-Column Versus Bottom-Sediments of Prairie Rivers.
Department of Soil Science, University of Manitoba, Ellis Building, 13 Freedman Crescent, Winnipeg, MB, R3T 2N2, Canada.; Agriculture and Agri-Food Canada, 5403 1st Avenue South, Lethbridge, AB, T1J 4B1, Canada.; Department of Soil Science, University of Manitoba, Ellis Building, 13 Freedman Crescent, Winnipeg, MB, R3T 2N2, Canada. muniras@myumanitoba.ca.
River water-column and bottom-sediments samples were screened for 160 pesticide compounds to compare the types of pesticides present in the water-column versus bottom-sediments, and between segments of rivers flowing through intensively-managed versus semi-natural habitats. Of the 35 pesticide compounds detected, current-use pesticides accounted for 96% (water) and 76% (bottom sediments). Pesticide mixtures were present in 72% (water) and 51% (sediment) of the total samples. Only the river flowing through the most intensively managed habitat showed a wide range of pesticides in sediments, and many of these pesticides were also present in the water-column of that river. Current-use fungicides were detected in both the water-column and bottom-sediments but not in samples taken from rivers flowing predominantly through semi-natural habitats. The study period (May to August) corresponds to the peak time of regional pesticide applications and hence the time period that is most likely to show elevated concentrations of current-use pesticides in the water-column. The environmental concentrations of pesticide mixtures detected in the water-column were used to calculate Pesticide Toxicity Index (PTI) values as it applies to non-vascular or vascular plants, invertebrates, and fish. The PTI values were largest for non-vascular and vascular plants, reflecting that the pesticide mixtures in water-column were dominated by herbicides.
PMID: 34014360