Annu Rev Plant Biol , IF:19.54 , 2020 Apr , V71 : P403-433 doi: 10.1146/annurev-arplant-050718-100005
Salt Tolerance Mechanisms of Plants.
Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands; email: christa.testerink@wur.nl.
Crop loss due to soil salinization is an increasing threat to agriculture worldwide. This review provides an overview of cellular and physiological mechanisms in plant responses to salt. We place cellular responses in a time- and tissue-dependent context in order to link them to observed phases in growth rate that occur in response to stress. Recent advances in phenotyping can now functionally or genetically link cellular signaling responses, ion transport, water management, and gene expression to growth, development, and survival. Halophytes, which are naturally salt-tolerant plants, are highlighted as success stories to learn from. We emphasize that (a) filling the major knowledge gaps in salt-induced signaling pathways, (b) increasing the spatial and temporal resolution of our knowledge of salt stress responses, (c) discovering and considering crop-specific responses, and (d) including halophytes in our comparative studies are all essential in order to take our approaches to increasing crop yields in saline soils to the next level.
PMID: 32167791
Annu Rev Plant Biol , IF:19.54 , 2020 Apr , V71 : P379-402 doi: 10.1146/annurev-arplant-073019-025907
Rapid Auxin-Mediated Cell Expansion.
Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota 55108, USA; email: dum@umn.edu, grayx051@umn.edu.; Department of Botany, University of Wisconsin, Madison, Wisconsin 53706, USA; email: spalding@wisc.edu.
The promotive effect of auxin on shoot cell expansion provided the bioassay used to isolate this central plant hormone nearly a century ago. While the mechanisms underlying auxin perception and signaling to regulate transcription have largely been elucidated, how auxin controls cell expansion is only now attaining molecular-level definition. The good news is that the decades-old acid growth theory invoking plasma membrane H(+)-ATPase activation is still useful. The better news is that a mechanistic framework has emerged, wherein Small Auxin Up RNA (SAUR) proteins regulate protein phosphatases to control H(+)-ATPase activity. In this review, we focus on rapid auxin effects, their relationship to H(+)-ATPase activation and other transporters, and dependence on TIR1/AFB signaling. We also discuss how some observations, such as near-instantaneous effects on ion transport and root growth, do not fit into a single, comprehensive explanation of how auxin controls cell expansion, and where more research is warranted.
PMID: 32131604
Annu Rev Plant Biol , IF:19.54 , 2020 Apr , V71 : P327-353 doi: 10.1146/annurev-arplant-050718-100309
Evolution of Plant Hormone Response Pathways.
Instituto de Biologia Molecular y Celular de Plantas, Consejo Superior de Investigaciones Cientificas-Universidad Politecnica de Valencia, 46022 Valencia, Spain; email: mblazquez@ibmcp.upv.es.; Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA; email: david.nelson@ucr.edu.; Laboratory of Biochemistry, Wageningen University, 6708WE Wageningen, The Netherlands; email: dolf.weijers@wur.nl.
This review focuses on the evolution of plant hormone signaling pathways. Like the chemical nature of the hormones themselves, the signaling pathways are diverse. Therefore, we focus on a group of hormones whose primary perception mechanism involves an Skp1/Cullin/F-box-type ubiquitin ligase: auxin, jasmonic acid, gibberellic acid, and strigolactone. We begin with a comparison of the core signaling pathways of these four hormones, which have been established through studies conducted in model organisms in the Angiosperms. With the advent of next-generation sequencing and advanced tools for genetic manipulation, the door to understanding the origins of hormone signaling mechanisms in plants beyond these few model systems has opened. For example, in-depth phylogenetic analyses of hormone signaling components are now being complemented by genetic studies in early diverging land plants. Here we discuss recent investigations of how basal land plants make and sense hormones. Finally, we propose connections between the emergence of hormone signaling complexity and major developmental transitions in plant evolution.
PMID: 32017604
Trends Plant Sci , IF:14.416 , 2020 Apr , V25 (4) : P325-328 doi: 10.1016/j.tplants.2020.01.002
Proteolytic Proteoforms: Elusive Components of Hormonal Pathways?
Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden.; Department of Biology, University of Crete, Heraklion, Crete, Greece; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Crete, Greece.; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; VIB Center for Plant Systems Biology, 9052 Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium; VIB Center for Medical Biotechnology, 9000 Ghent, Belgium. Electronic address: simon.stael@psb.vib-ugent.be.; Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden; Department of Biology, University of Crete, Heraklion, Crete, Greece; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Crete, Greece.
Hormonal pathways often converge on transcriptional repressors that can be degraded by the proteasome to initiate a response. We wish to draw attention to developments in a less-explored proteolytic branch called 'limited proteolysis' that, in addition to the classical proteolytic pathways, seems to regulate auxin and ethylene signaling.
PMID: 32191869
Nat Chem Biol , IF:12.587 , 2020 Apr doi: 10.1038/s41589-020-0519-8
Modulation of auxin formation by the cytosolic phenylalanine biosynthetic pathway.
Department of Biochemistry, Purdue University, West Lafayette, IN, USA.; Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, USA.; Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, USA.; WuXi Biologics, Wuxi, China.; Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, USA.; Jack H Skirball Center for Chemical Biology and Proteomics, Salk Institute for Biological Studies, La Jolla, CA, USA.; Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA, USA.; Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN, USA.; Department of Biochemistry, Purdue University, West Lafayette, IN, USA. dudareva@purdue.edu.; Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, USA. dudareva@purdue.edu.; Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, USA. dudareva@purdue.edu.
In plants, phenylalanine biosynthesis occurs via two compartmentally separated pathways. Overexpression of petunia chorismate mutase 2 (PhCM2), which catalyzes the committed step of the cytosolic pathway, increased flux in cytosolic phenylalanine biosynthesis, but paradoxically decreased the overall levels of phenylalanine and phenylalanine-derived volatiles. Concomitantly, the levels of auxins, including indole-3-acetic acid and its precursor indole-3-pyruvic acid, were elevated. Biochemical and genetic analyses revealed the existence of metabolic crosstalk between the cytosolic phenylalanine biosynthesis and tryptophan-dependent auxin biosynthesis mediated by an aminotransferase that uses a cytosolic phenylalanine biosynthetic pathway intermediate, phenylpyruvate, as an amino acceptor for auxin formation.
PMID: 32284603
Nucleic Acids Res , IF:11.501 , 2020 Apr , V48 (6) : P3195-3210 doi: 10.1093/nar/gkaa129
The critical function of the plastid rRNA methyltransferase, CMAL, in ribosome biogenesis and plant development.
Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.; University of Chinese Academy of Sciences, Beijing 100049, China.; Key Laboratory of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng 475004, China.; Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University, Munich, D-82152 Planegg-Martinsried, Germany.
Methylation of nucleotides in ribosomal RNAs (rRNAs) is a ubiquitous feature that occurs in all living organisms. The formation of methylated nucleotides is performed by a variety of RNA-methyltransferases. Chloroplasts of plant cells result from an endosymbiotic event and possess their own genome and ribosomes. However, enzymes responsible for rRNA methylation and the function of modified nucleotides in chloroplasts remain to be determined. Here, we identified an rRNA methyltransferase, CMAL (Chloroplast MraW-Like), in the Arabidopsis chloroplast and investigated its function. CMAL is the Arabidopsis ortholog of bacterial MraW/ RsmH proteins and accounts to the N4-methylation of C1352 in chloroplast 16S rRNA, indicating that CMAL orthologs and this methyl-modification nucleotide is conserved between bacteria and the endosymbiont-derived eukaryotic organelle. The knockout of CMAL in Arabidopsis impairs the chloroplast ribosome accumulation and accordingly reduced the efficiency of mRNA translation. Interestingly, the loss of CMAL leads not only to defects in chloroplast function, but also to abnormal leaf and root development and overall plant morphology. Further investigation showed that CMAL is involved in the plant development probably by modulating auxin derived signaling pathways. This study uncovered the important role of 16S rRNA methylation mediated by CMAL in chloroplast ribosome biogenesis and plant development.
PMID: 32095829
Curr Biol , IF:9.601 , 2020 Apr , V30 (8) : P1454-1466.e6 doi: 10.1016/j.cub.2020.02.017
AT-Hook Transcription Factors Restrict Petiole Growth by Antagonizing PIFs.
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164 USA; Molecular Plant Sciences Graduate Program, Washington State University, Pullman, WA 99164 USA. Electronic address: david.favero@riken.jp.; RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan.; Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK; Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, South Korea.; Department of Biological Chemistry, College of Biosciences and Biotechnology, Chubu University, Kasugai, Aichi 487-8501, Japan.; Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK; Leibniz-Institut fur Gemuse- und Zierpflanzenbau (IGZ), Grossbeeren 14979 Germany.; Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164 USA; Molecular Plant Sciences Graduate Program, Washington State University, Pullman, WA 99164 USA.; RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; Department of Biological Sciences, The University of Tokyo, Tokyo 119-0033, Japan.
Upon detecting abiotic or biotic stress, plants generally reduce their growth, enabling resources to be conserved and diverted to stress response mechanisms. In Arabidopsis thaliana, the AT-hook motif nuclear-localized (AHL) transcription factor family has been implicated in restricting rosette growth in response to stress. However, the mechanism by which AHLs repress growth in rosettes is unknown. In this study, we establish that SUPPRESSOR OF PHYTOCHROME B4-#3 (SOB3) and other AHLs restrict petiole elongation by antagonizing the growth-promoting PHYTOCHROME-INTERACTING FACTORs (PIFs). Our data show that high levels of SOB3 expression lead to a short-petiole phenotype similar to that conferred by removal of PIF4. Conversely, the dominant-negative sob3-6 mutant has long petioles, a phenotype which is PIF-dependent. We further show that AHLs repress the expression of many PIF-activated genes, several of which are involved in hormone-mediated promotion of growth. Additionally, a subset of PIF-activated, AHL-repressed genes are directly bound by both SOB3 and PIFs. Finally, SOB3 reduces binding of PIF4 to shared target loci. Collectively, our results demonstrate that AHLs repress petiole growth by antagonizing PIF-mediated transcriptional activation of genes associated with growth and hormone pathways. By elucidating a mechanism via which the stress-responsive AHL transcription factor family influences growth in petioles, this study identifies a key step in the gene regulatory network controlling leaf growth in response to the environment.
PMID: 32197081
Proc Natl Acad Sci U S A , IF:9.412 , 2020 Apr , V117 (16) : P9112-9121 doi: 10.1073/pnas.1918254117
Distinct modes of manipulation of rice auxin response factor OsARF17 by different plant RNA viruses for infection.
State Key Laboratory for Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture of China and Zhejiang Province, Institute of Plant Virology, Ningbo University, 315211 Ningbo, China.; Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, 310021 Hangzhou, China.; College of Life Sciences, Peking University, 100871 Beijing, China.; State Key Laboratory for Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of Ministry of Agriculture of China and Zhejiang Province, Institute of Plant Virology, Ningbo University, 315211 Ningbo, China; jpchen2001@126.com sunzongtao@nbu.edu.cn.
Plant auxin response factor (ARF) transcription factors are an important class of key transcriptional modulators in auxin signaling. Despite the well-studied roles of ARF transcription factors in plant growth and development, it is largely unknown whether, and how, ARF transcription factors may be involved in plant resistance to pathogens. We show here that two fijiviruses (double-stranded RNA viruses) utilize their proteins to disturb the dimerization of OsARF17 and repress its transcriptional activation ability, while a tenuivirus (negative-sense single-stranded RNA virus) directly interferes with the DNA binding activity of OsARF17. These interactions impair OsARF17-mediated antiviral defense. OsARF17 also confers resistance to a cytorhabdovirus and was directly targeted by one of the viral proteins. Thus, OsARF17 is the common target of several very different viruses. This suggests that OsARF17 plays a crucial role in plant defense against different types of plant viruses, and that these viruses use independently evolved viral proteins to target this key component of auxin signaling and facilitate infection.
PMID: 32253321
Proc Natl Acad Sci U S A , IF:9.412 , 2020 Apr , V117 (14) : P7558-7560 doi: 10.1073/pnas.2003305117
Sugar rush: Glucosylation of IPyA attenuates auxin levels.
Department of Biology, Washington University in St. Louis, St. Louis, MO 63130.; Center for Science and Engineering of Living Systems, Washington University in St. Louis, St. Louis, MO 63130.; Department of Biology, Washington University in St. Louis, St. Louis, MO 63130; strader@wustl.edu.; Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO 63130.
PMID: 32193342
New Phytol , IF:8.512 , 2020 Apr doi: 10.1111/nph.16633
A role for the Auxin Response Factors ARF6 and ARF8 homologs in petal spur elongation and nectary maturation in Aquilegia.
State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.; Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave, Cambridge, MA, 02138, USA.; 10x Genomics, 6230 Stoneridge Mall Road, Pleasanton, CA, 94588-3260, USA.; Harvard University Herbaria, Harvard University, 22 Divinity Ave, Cambridge, MA, 02138, USA.
The petal spur of the basal eudicot Aquilegia is a key innovation associated with the adaptive radiation of the genus. Previous studies have shown that diversification of Aquilegia spur length can be predominantly attributed to variation in cell elongation. However, the genetic pathways that control the development of petal spurs are still being investigated. Here, we focus on a pair of closely related homologs of the AUXIN RESPONSE FACTOR family, AqARF6 and AqARF8, to explore their roles in Aquileiga coerulea petal spur development. Expression analyses of the two genes show that they are broadly expressed in vegetative and floral organs, but have relatively higher expression in petal spurs, particularly at later stages. Knockdown of the two AqARF6 and AqARF8 transcripts using virus-induced gene silencing resulted in largely petal-specific defects, including a significant reduction in spur length due to a decrease in cell elongation. These spurs also exhibited an absence of nectar production, which was correlated with downregulation of STYLISH homologs that have previously been shown to control nectary development. This study provides the first evidence of ARF6/8 homolog-mediated petal development outside the core eudicots. The genes appear to be specifically required for cell elongation and nectary maturation in the Aquilegia petal spur.
PMID: 32356309
New Phytol , IF:8.512 , 2020 Apr doi: 10.1111/nph.16629
Directional auxin fluxes in plants by intramolecular domain-domain coevolution of PIN auxin transporters.
Institute of Science and Technology (IST) Austria, Klosterneuburg, 3400, Austria.; College of Life Sciences, Northwest University, Xi'an, 710069, China.
Morphogenesis and adaptive tropic growth in plants depend on gradients of the phytohormone auxin, mediated by the membrane-based PIN-FORMED (PIN) auxin transporters. PINs localize to a particular side of the plasma membrane (PM) or to the endoplasmic reticulum (ER) to directionally transport auxin and maintain intercellular and intracellular auxin homeostasis, respectively. However, the molecular cues that confer their diverse cellular localizations remain largely unknown. In this study, we systematically swapped the domains between ER- and PM-localized PIN proteins, as well as between apical and basal PM-localized PINs from Arabidopsis thaliana, to shed light on why PIN family members with similar topological structures reside at different membrane compartments within cells. Our results show that not only do the N- and C-terminal transmembrane domains (TMDs) and central hydrophilic loop contribute to their differential subcellular localizations and cellular polarity, but that the pairwise-matched N- and C-terminal TMDs resulting from intramolecular domain-domain coevolution are also crucial for their divergent patterns of localization. These findings illustrate the complexity of the evolutionary path of PIN proteins in acquiring their plethora of developmental functions and adaptive growth in plants.
PMID: 32350870
New Phytol , IF:8.512 , 2020 Apr , V226 (2) : P441-459 doi: 10.1111/nph.16382
Auxin-induced actin cytoskeleton rearrangements require AUX1.
Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907-2064, USA.; Purdue University Interdisciplinary Life Sciences Graduate Program (PULSe), Purdue University, West Lafayette, IN, 47907, USA.; Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA.; Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.
The actin cytoskeleton is required for cell expansion and implicated in cellular responses to the phytohormone auxin. However, the mechanisms that coordinate auxin signaling, cytoskeletal remodeling and cell expansion are poorly understood. Previous studies examined long-term actin cytoskeleton responses to auxin, but plants respond to auxin within minutes. Before this work, an extracellular auxin receptor - rather than the auxin transporter AUXIN RESISTANT 1 (AUX1) - was considered to precede auxin-induced cytoskeleton reorganization. In order to correlate actin array organization and dynamics with degree of cell expansion, quantitative imaging tools established baseline actin organization and illuminated individual filament behaviors in root epidermal cells under control conditions and after indole-3-acetic acid (IAA) application. We evaluated aux1 mutant actin organization responses to IAA and the membrane-permeable auxin 1-naphthylacetic acid (NAA). Cell length predicted actin organization and dynamics in control roots; short-term IAA treatments stimulated denser and more parallel, longitudinal arrays by inducing filament unbundling within minutes. Although AUX1 is necessary for full actin rearrangements in response to auxin, cytoplasmic auxin (i.e. NAA) stimulated a lesser response. Actin filaments became more 'organized' after IAA stopped elongation, refuting the hypothesis that 'more organized' actin arrays universally correlate with rapid growth. Short-term actin cytoskeleton response to auxin requires AUX1 and/or cytoplasmic auxin.
PMID: 31859367
New Phytol , IF:8.512 , 2020 Apr , V226 (1) : P142-155 doi: 10.1111/nph.16330
Phospholipase D-derived phosphatidic acid promotes root hair development under phosphorus deficiency by suppressing vacuolar degradation of PIN-FORMED2.
Collaborative Innovation Center of Henan Grain Crops/State Key Laboratory of Wheat and Maize Crop Science, College of Life Sciences, Henan Agricultural University, 450002, Zhengzhou, China.; National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese academy of Sciences, 200032, Shanghai, China.; College of Resource and Environment, Henan Agricultural University, 450002, Zhengzhou, China.; Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 200240, Shanghai, China.
Root hair development is crucial for phosphate absorption, but how phosphorus deficiency affects root hair initiation and elongation remains unclear. We demonstrated the roles of auxin efflux carrier PIN-FORMED2 (PIN2) and phospholipase D (PLD)-derived phosphatidic acid (PA), a key signaling molecule, in promoting root hair development in Arabidopsis thaliana under a low phosphate (LP) condition. Root hair elongation under LP conditions was greatly suppressed in pin2 mutant or under treatment with a PLDzeta2-specific inhibitor, revealing that PIN2 and polar auxin transport and PLDzeta2-PA are crucial in LP responses. PIN2 was accumulated and degraded in the vacuole under a normal phosphate (NP) condition, whereas its vacuolar accumulation was suppressed under the LP or NP plus PA conditions. Vacuolar accumulation of PIN2 was increased in pldzeta2 mutants under LP conditions. Increased or decreased PIN2 vacuolar accumulation is not observed in sorting nexin1 (snx1) mutant, indicating that vacuolar accumulation of PIN2 is mediated by SNX1 and the relevant trafficking process. PA binds to SNX1 and promotes its accumulation at the plasma membrane, especially under LP conditions, and hence promotes root hair development by suppressing the vacuolar degradation of PIN2. We uncovered a link between PLD-derived PA and SNX1-dependent vacuolar degradation of PIN2 in regulating root hair development under phosphorus deficiency.
PMID: 31745997
Plant Biotechnol J , IF:8.154 , 2020 Apr , V18 (4) : P1078-1092 doi: 10.1111/pbi.13277
Regulatory changes in TaSNAC8-6A are associated with drought tolerance in wheat seedlings.
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China.
Wheat is a staple crop produced in arid and semi-arid areas worldwide, and its production is frequently compromised by water scarcity. Thus, increased drought tolerance is a priority objective for wheat breeding programmes, and among their targets, the NAC transcription factors have been demonstrated to contribute to plant drought response. However, natural sequence variations in these genes have been largely unexplored for their potential roles in drought tolerance. Here, we conducted a candidate gene association analysis of the stress-responsive NAC gene subfamily in a wheat panel consisting of 700 varieties collected worldwide. We identified a drought responsive gene, TaSNAC8-6A, that is tightly associated with drought tolerance in wheat seedlings. Further analysis found that a favourable allele TaSNAC8-6A(In-313) , carrying an insertion in the ABRE promoter motif, is targeted by TaABFs and confers enhanced drought-inducible expression of TaSNAC8-6A in drought-tolerant genotypes. Transgenic wheat and Arabidopsis TaSNAC8-6A overexpression lines exhibited enhanced drought tolerance through induction of auxin- and drought-response pathways, confirmed by transcriptomic analysis, that stimulated lateral root development, subsequently improving water-use efficiency. Taken together, our findings reveal that natural variation in TaSNAC8-6A and specifically the TaSNAC8-6A(In-313) allele strongly contribute to wheat drought tolerance and thus represent a valuable genetic resource for improvement of drought-tolerant germplasm for wheat production.
PMID: 31617659
Plant Biotechnol J , IF:8.154 , 2020 Apr , V18 (4) : P1004-1014 doi: 10.1111/pbi.13267
The retromer protein ZmVPS29 regulates maize kernel morphology likely through an auxin-dependent process(es).
Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.; School of Life Sciences, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, China.
Kernel size and morphology are two important yield-determining traits in maize, but their molecular and genetic mechanisms are poorly characterized. Here, we identified a major QTL, qKM4.08, which explains approximately 24.20% of the kernel morphology variance in a recombinant population derived from two elite maize inbred lines, Huangzaosi (HZS, round kernel) and LV28 (slender kernel). Positional cloning and transgenic analysis revealed that qKM4.08 encodes ZmVPS29, a retromer complex component. Compared with the ZmVPS29 HZS allele, the ZmVPS29 LV28 allele showed higher expression in developing kernels. Overexpression of ZmVPS29 conferred a slender kernel morphology and increased the yield per plant in different maize genetic backgrounds. Sequence analysis revealed that ZmVPS29 has been under purifying selection during maize domestication. Association analyses identified two significant kernel morphology-associated polymorphic sites in the ZmVPS29 promoter region that were significantly enriched in modern maize breeding lines. Further study showed that ZmVPS29 increased auxin accumulation during early kernel development by enhancing auxin biosynthesis and transport and reducing auxin degradation and thereby improved kernel development. Our results suggest that ZmVPS29 regulates kernel morphology, most likely through an auxin-dependent process(es).
PMID: 31553822
Plant Biotechnol J , IF:8.154 , 2020 Apr , V18 (4) : P929-943 doi: 10.1111/pbi.13257
Characterizing the involvement of FaMADS9 in the regulation of strawberry fruit receptacle development.
Departamento de Biologia Molecular y Bioquimica. Campus de Teatinos, Instituto de Hortofruticultura Subtropical y Mediterranea 'La Mayora', Universidad de Malaga-Consejo Superior de Investigaciones Cientificas, Malaga, Spain.; Unidad Asociada IFAPA-CSIC Biotecnologia y Mejora en Fresa, Malaga, Spain.; Genomica y Biotecnologia, Centro de Malaga, Instituto Andaluz de Investigacion y Formacion Agraria y Pesquera (IFAPA), Malaga, Spain.; Plant and Microbial Biology Department, North Carolina State University, Raleigh, NC, USA.; Max-Planck-Institut fur Molekulare Pflanzenphysiologie, Potsdam-Golm, Germany.; Departmento de Genetica Molecular de Plantas, Centro Nacional de Biotecnologia, Consejo Superior de Investigaciones Cientificas (CNB-CSIC), Madrid, Spain.; Biomathematics Program, North Carolina State University, Raleigh, NC, USA.; Boyce Thompson Institute for Plant Research and USDA-ARS, Robert W. Holley Center, Cornell University Campus, Ithaca, NY, USA.
FaMADS9 is the strawberry (Fragaria x ananassa) gene that exhibits the highest homology to the tomato (Solanum lycopersicum) RIN gene. Transgenic lines were obtained in which FaMADS9 was silenced. The fruits of these lines did not show differences in basic parameters, such as fruit firmness or colour, but exhibited lower Brix values in three of the four independent lines. The gene ontology MapMan category that was most enriched among the differentially expressed genes in the receptacles at the white stage corresponded to the regulation of transcription, including a high percentage of transcription factors and regulatory proteins associated with auxin action. In contrast, the most enriched categories at the red stage were transport, lipid metabolism and cell wall. Metabolomic analysis of the receptacles of the transformed fruits identified significant changes in the content of maltose, galactonic acid-1,4-lactone, proanthocyanidins and flavonols at the green/white stage, while isomaltose, anthocyanins and cuticular wax metabolism were the most affected at the red stage. Among the regulatory genes that were differentially expressed in the transgenic receptacles were several genes previously linked to flavonoid metabolism, such as MYB10, DIV, ZFN1, ZFN2, GT2, and GT5, or associated with the action of hormones, such as abscisic acid, SHP, ASR, GTE7 and SnRK2.7. The inference of a gene regulatory network, based on a dynamic Bayesian approach, among the genes differentially expressed in the transgenic receptacles at the white and red stages, identified the genes KAN1, DIV, ZFN2 and GTE7 as putative targets of FaMADS9. A MADS9-specific CArG box was identified in the promoters of these genes.
PMID: 31533196
Cell Rep , IF:8.109 , 2020 Apr , V31 (3) : P107529 doi: 10.1016/j.celrep.2020.107529
The Asymmetric Expression of SAUR Genes Mediated by ARF7/19 Promotes the Gravitropism and Phototropism of Plant Hypocotyls.
State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.; State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China. Electronic address: chenhaodong@pku.edu.cn.
The asymmetric distribution of auxin leads to the bending growth of hypocotyls during gravitropic and phototropic responses, but the signaling events downstream of auxin remain unclear. Here, we identify many SAUR genes showing asymmetric expression in soybean hypocotyls during gravistimulation and then study their homologs in Arabidopsis. SAUR19 subfamily genes have asymmetric expression in Arabidopsis hypocotyls during gravitropic and phototropic responses, induced by the lateral redistribution of auxin. Both the mutation of SAUR19 subfamily genes and the ectopic expression of SAUR19 weaken these tropic responses, indicating the critical role of their asymmetric expression. The auxin-responsive transcription factor ARF7 may directly bind the SAUR19 promoter and activate SAUR19 expression asymmetrically in tropic responses. Taken together, our results reveal that a gravity- or light-triggered asymmetric auxin distribution induces the asymmetric expression of SAUR19 subfamily genes by ARF7 and ARF19 in the hypocotyls, which leads to bending growth during gravitropic and phototropic responses.
PMID: 32320660
Elife , IF:7.08 , 2020 Apr , V9 doi: 10.7554/eLife.51787
Direct ETTIN-auxin interaction controls chromatin states in gynoecium development.
Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, United Kingdom.; Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.; Institute of Science and Technology, Klosterneuburg, Austria.
Hormonal signalling in animals often involves direct transcription factor-hormone interactions that modulate gene expression. In contrast, plant hormone signalling is most commonly based on de-repression via the degradation of transcriptional repressors. Recently, we uncovered a non-canonical signalling mechanism for the plant hormone auxin whereby auxin directly affects the activity of the atypical auxin response factor (ARF), ETTIN towards target genes without the requirement for protein degradation. Here we show that ETTIN directly binds auxin, leading to dissociation from co-repressor proteins of the TOPLESS/TOPLESS-RELATED family followed by histone acetylation and induction of gene expression. This mechanism is reminiscent of animal hormone signalling as it affects the activity towards regulation of target genes and provides the first example of a DNA-bound hormone receptor in plants. Whilst auxin affects canonical ARFs indirectly by facilitating degradation of Aux/IAA repressors, direct ETTIN-auxin interactions allow switching between repressive and de-repressive chromatin states in an instantly-reversible manner.
PMID: 32267233
Plant Physiol , IF:6.902 , 2020 Apr , V182 (4) : P1713-1722 doi: 10.1104/pp.19.01475
A Synthetic Approach Allows Rapid Characterization of the Maize Nuclear Auxin Response Circuit.
University of Washington, Department of Biology, Seattle, Washington 98105.; Whitman College, Department of Biology, Walla Walla, Washington 99362.; Waksman Institute of Microbiology, Rutgers University, Piscataway, New Jersey 08854-8020.; Department of Plant Biology, Rutgers University, New Brunswick, New Jersey 08901.; Whitman College, Department of Biology, Walla Walla, Washington 99362 mossbl@whitman.edu.
Auxin plays a key role across all land plants in growth and developmental processes. Although auxin signaling function has diverged and expanded, differences in the molecular functions of signaling components have largely been characterized in Arabidopsis (Arabidopsis thaliana). Here, we used the nuclear Auxin Response Circuit recapitulated in yeast (Saccharomyces cerevisiae) system to functionally annotate maize (Zea mays) auxin signaling components, focusing on genes expressed during the development of ear and tassel inflorescences. All 16 maize auxin/indole-3-acetic acid repressor proteins were degraded in response to auxin with rates that depended on both receptor and repressor identities. When fused to the maize TOPLESS homolog RAMOSA1 ENHANCER LOCUS2, maize auxin/indole-3-acetic acids were able to repress AUXIN RESPONSE FACTOR transcriptional activity. A complete auxin response circuit comprising all maize components, including the ZmAFB2/3 b1 maize AUXIN SIGNALING F-BOX (AFB) receptor, was fully functional. The ZmAFB2/3 b1 auxin receptor was more sensitive to hormone than AtAFB2 and allowed for rapid circuit activation upon auxin addition. These results validate the conserved role of predicted auxin response genes in maize as well as provide evidence that a synthetic approach can facilitate broader comparative studies across the wide range of species with sequenced genomes.
PMID: 32123041
Plant Physiol , IF:6.902 , 2020 Apr , V182 (4) : P2096-2110 doi: 10.1104/pp.19.01501
Class-I TCP Transcription Factors Activate the SAUR63 Gene Subfamily in Gibberellin-Dependent Stamen Filament Elongation.
Instituto de Agrobiotecnologia del Litoral, Catedra de Biologia Celular y Molecular, Facultad de Bioquimica y Ciencias Biologicas, Universidad Nacional del Litoral, 3000 Santa Fe, Argentina.; Instituto de Agrobiotecnologia del Litoral, Catedra de Biologia Celular y Molecular, Facultad de Bioquimica y Ciencias Biologicas, Universidad Nacional del Litoral, 3000 Santa Fe, Argentina dhgonza@fbcb.unl.edu.ar.
In autogamous plants like Arabidopsis (Arabidopsis thaliana), stamen filament elongation must be finely regulated to ensure that anthers reach the pistil at the correct developmental stage. In this work, we studied the roles of Arabidopsis TEOSINTE BRANCHED1, CYCLOIDEA, PCF15 (TCP15), and related class-I TCP transcription factors in stamen filament elongation. Plants with decreased expression of class-I TCPs and plants that express a fusion of TCP15 to a repressor domain (pTCP15::TCP15-EAR) had shorter stamens, indicating that class-I TCPs stimulate filament growth. These plants also showed reduced expression of several SMALL AUXIN UP RNA (SAUR)63 subfamily genes, which contain TCP target motifs in their promoters. Mutational analysis indicated that the TCP target motif in the SAUR63 promoter is required for expression of SAUR63 in stamen filaments. Moreover, TCP15 directly binds to the SAUR63 promoter region that contains the TCP target motif in vivo, highlighting the role of the TCPs in this process. Class-I TCPs are also required for the induction of SAUR63 subfamily genes by gibberellins (GAs). In addition, overexpression of SAUR63 restores filament growth in pTCP15::TCP15-EAR plants, whereas overexpression of TCP15 rescues the short stamen phenotype of GA-deficient plants. The results indicate that TCP15 and related class-I TCPs modulate GA-dependent stamen filament elongation by direct activation of SAUR63 subfamily genes through conserved target sites in their promoters. This work provides insight into GA-dependent stamen filament elongation.
PMID: 31988200
Plant J , IF:6.141 , 2020 Apr , V102 (1) : P18-33 doi: 10.1111/tpj.14608
Arabidopsis PIC30 encodes a major facilitator superfamily transporter responsible for the uptake of picolinate herbicides.
Department of Biology, Texas State University, 601 University Drive, San Marcos, TX, 78666.; Department of Molecular Biosciences, University of Texas, Austin, TX 78712, USA.; Department of Biochemistry, and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, 37996.
Picloram is an auxinic herbicide that is widely used for controlling broad leaf weeds. However, its mechanism of transport into plants is poorly understood. In a genetic screen for picloram resistance, we identified three Arabidopsis mutant alleles of PIC30 (PICLORAM RESISTANT30) that are specifically resistant to picolinates, but not to other auxins. PIC30 is a previously uncharacterized gene that encodes a major facilitator superfamily (MFS) transporter. Similar to most members of MFS, PIC30 contains 12 putative transmembrane domains, and PIC30-GFP fusion protein selectively localizes to the plasma membrane. In planta transport assays demonstrate that PIC30 specifically transports picloram, but not indole-3-acetic acid (IAA). Functional analysis of Xenopus laevis oocytes injected with PIC30 cRNA demonstrated PIC30 mediated transport of picloram and several anions, including nitrate and chloride. Consistent with these roles of PIC30, three allelic pic30 mutants are selectively insensitive to picolinate herbicides, while pic30-3 is also defective in chlorate (analogue of nitrate) transport and also shows reduced uptake of 15 N O 3 - . Overexpression of PIC30 fully complements both picloram and chlorate insensitive phenotypes of pic30-3. Despite the continued use of picloram as an herbicide, a transporter for picloram was not known until now. This work provides insight into the mechanisms of plant resistance to picolinate herbicides and also shed light on the possible endogenous function of PIC30 protein.
PMID: 31710151
J Exp Bot , IF:5.908 , 2020 Apr doi: 10.1093/jxb/eraa195
A Glutathione-dependent control of IBA pathway supports Arabidopsis root system adaptation to phosphate deprivation.
Univ. Perpignan Via Domitia, Laboratoire Genome et Developpement des Plantes, UMR, F, Perpignan, France.; CNRS, Laboratoire Genome et Developpement des Plantes, UMR, F, Perpignan, France.; NSF Science and Technology Center for Engineering Mechanobiology, Department of Biology, Washington University in St. Louis, St. Louis, MO, USA.
Root system architecture results from a highly plastic developmental process to adapt to environmental conditions. In particular, the development of lateral roots (LR) and root hair (RH) growth are constantly optimized to the rhizosphere properties, including biotic and abiotic constraints. Root system development is tightly controlled by auxin, the driving morphogenic hormone in plants. Glutathione, a major thiol redox regulator, is also critical for root development but its interplay with auxin is scarcely understood. Previous works showed that glutathione deficiency does not alter root responses to indole acetic acid (IAA), the main active auxin in plants. Because indole butyric acid (IBA), another endogenous auxinic compound, is an important source of IAA for the control of root development, we investigated the crosstalk between glutathione and IBA during root development. We show that glutathione deficiency alters LR and RH responses to exogenous IBA but not IAA. Detailed genetic analyses suggest that glutathione regulates IBA homeostasis or conversion to IAA in the root cap. Finally, we show that both glutathione and IBA are required for the proper responses of RH to phosphate deprivation, suggesting an important role for this glutathione-dependent regulation of auxin pathway in plant developmental adaptation to its environment.
PMID: 32309856
J Exp Bot , IF:5.908 , 2020 Apr doi: 10.1093/jxb/eraa187
How does nitrogen shape plant architecture?
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, China.; China MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing, China.
Plant nitrogen (N) acquired mainly in forms of nitrate and ammonium from soil dominates growth and development, and high-yield crop production relies heavily on N fertilization. The mechanisms of root adaptation to altered supply of N forms and concentrations have been well characterized and reviewed, while reports concerning effects of N on the architecture of vegetative and reproductive organs are limited and are widely dispersed in the literature. In this review, we summarize the nitrate and amino acid regulation of shoot branching, flowering and panicle development, as well as the N regulation of cell division and expansion in shaping the plant architecture mainly in cereal crops. The basic regulatory steps involving the N supply to control the plant architecture are auxin-, cytokinin-, and strigolactone-controlled cell division in shoot apical meristem and gibberellin-controlled inverse regulation of shoot height and tillering. In addition, transport of amino acids has been shown to be involved in control of shoot branching. The N supply may alter the time and duration of the transition from vegetative to reproductive growth phases, which may in turn affect cereal crop architecture, particularly the structure of panicles for grain yield. Thus, properly manipulating N-regulated architecture can increase the crop yield and N use efficiency.
PMID: 32279073
J Exp Bot , IF:5.908 , 2020 Apr , V71 (8) : P2390-2396 doi: 10.1093/jxb/eraa079
Dissecting mechanisms in root growth from the transition zone perspective.
Department of Biology and Biotechnology "Charles Darwin", Laboratory of Functional Genomics and Proteomics of Model Systems, Sapienza University of Rome, Rome, Italy.; Department of Biology, University of Pisa, Pisa, Italy.
The root of the plant Arabidopsis thaliana is a dynamic structure in which cells continuously divide and differentiate to sustain its postembryonic undetermined growth. Cells at different developmental stages are organized in distinguished zones whose position and activities are maintained constant during root growth. In this review, we will discuss the latest discoveries on the regulatory networks involved in root zonation and, in particular, in the mechanisms involved in maintaining the position of the transition zone, a root developmental boundary. Developmental boundaries physically divide cells with different functions and identities. The transition zone separates dividing cells from differentiating cells in two functional domains, preserving their identity during root growth and thus controlling root development.
PMID: 32064533
Development , IF:5.611 , 2020 Apr , V147 (8) doi: 10.1242/dev.186130
Specification and regulation of vascular tissue identity in the Arabidopsis embryo.
Laboratory of Biochemistry, Wageningen University, Stippeneng 4, Wageningen, 6708WE, The Netherlands.; Novosibirsk State University, LCT&EB, Novosibirsk, 630090, Russia.; Institute of Cytology and Genetics, Novosibirsk, 630090, Russia.; Institute of Biotechnology, HiLIFE/Organismal and Evolurionary Biology Research Programma, Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, 00014, Finland.; Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, UK.; Max Planck Institute for Developmental Biology, Cell Biology, Tubingen, 72076, Germany.; Department of Plant Biology and Genome Center, University of California Davis, Davis, CA 95616, USA.; Laboratory of Biochemistry, Wageningen University, Stippeneng 4, Wageningen, 6708WE, The Netherlands dolf.weijers@wur.nl.
Development of plant vascular tissues involves tissue identity specification, growth, pattern formation and cell-type differentiation. Although later developmental steps are understood in some detail, it is still largely unknown how the tissue is initially specified. We used the early Arabidopsis embryo as a simple model to study this process. Using a large collection of marker genes, we found that vascular identity was specified in the 16-cell embryo. After a transient precursor state, however, there was no persistent uniform tissue identity. Auxin is intimately connected to vascular tissue development. We found that, although an AUXIN RESPONSE FACTOR5/MONOPTEROS (ARF5/MP)-dependent auxin response was required, it was not sufficient for tissue specification. We therefore used a large-scale enhanced yeast one-hybrid assay to identify potential regulators of vascular identity. Network and functional analysis of candidate regulators suggest that vascular identity is under robust, complex control. We found that one candidate regulator, the G-class bZIP transcription factor GBF2, can modulate vascular gene expression by tuning MP output through direct interaction. Our work uncovers components of a gene regulatory network that controls the initial specification of vascular tissue identity.
PMID: 32198154
Development , IF:5.611 , 2020 Apr , V147 (7) doi: 10.1242/dev.184788
Gene regulatory network controlling carpel number variation in cucumber.
State Key Laboratories of Agrobiotechnology, Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Sciences, China Agricultural University, Beijing 100193, China.; Analysis and Testing Centre, Hebei Normal University of Science and Technology, Qinhuangdao 066004, China.; Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China.; Center for Agroforestry Mega Data Science and FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China.; College of Horticulture Science and Technology, Hebei Normal University of Science and Technology, Qinhuangdao 066004, China.; USDA-ARS, Vegetable Crops Research Unit, Horticulture Department, University of Wisconsin-Madison, 1575 Linden Drive, Madison, WI 53706, USA.; State Key Laboratories of Agrobiotechnology, Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Sciences, China Agricultural University, Beijing 100193, China zhxiaolan@cau.edu.cn.
The WUSCHEL-CLAVATA3 pathway genes play an essential role in shoot apical meristem maintenance and floral organ development, and under intense selection during crop domestication. The carpel number is an important fruit trait that affects fruit shape, size and internal quality in cucumber, but the molecular mechanism remains elusive. Here, we found that CsCLV3 expression was negatively correlated with carpel number in cucumber cultivars. CsCLV3-RNAi led to increased number of petals and carpels, whereas overexpression of CsWUS resulted in more sepals, petals and carpels, suggesting that CsCLV3 and CsWUS function as a negative and a positive regulator for carpel number variation, respectively. Biochemical analyses indicated that CsWUS directly bound to the promoter of CsCLV3 and activated its expression. Overexpression of CsFUL1(A) , a FRUITFULL-like MADS-box gene, resulted in more petals and carpels. CsFUL1(A) can directly bind to the CsWUS promoter to stimulate its expression. Furthermore, we found that auxin participated in carpel number variation in cucumber through interaction of CsARF14 with CsWUS. Therefore, we have identified a gene regulatory pathway involving CsCLV3, CsWUS, CsFUL1(A) and CsARF14 in determining carpel number variation in an important vegetable crop - cucumber.
PMID: 32165491
PLoS Genet , IF:5.174 , 2020 Apr , V16 (4) : Pe1008661 doi: 10.1371/journal.pgen.1008661
An integrated analysis of cell-type specific gene expression reveals genes regulated by REVOLUTA and KANADI1 in the Arabidopsis shoot apical meristem.
European Molecular Biology Laboratory, Meyerhofstrasse, Heidelberg, Germany.; National Agri-Food Biotechnology Institute, SAS Nagar, Mohali, Punjab, India.; School of Life and Environmental Sciences, University of Sydney, NSW, Australia.
In the Arabidopsis thaliana shoot apical meristem (SAM) the expression domains of Class III Homeodomain Leucine Zipper (HD-ZIPIII) and KANADI (KAN) genes are separated by a narrow boundary region from which new organs are initiated. Disruption of this boundary through either loss of function or ectopic expression of HD-ZIPIII and KAN causes ectopic or suppression of organ formation respectively, raising the question of how these transcription factors regulate organogenesis at a molecular level. In this study we develop a multi-channel FACS/RNA-seq approach to characterize global patterns of gene expression across the HD-ZIPIII-KAN1 SAM boundary. We then combine FACS, RNA-seq and perturbations of HD-ZIPIII and KAN expression to identify genes that are both responsive to REV and KAN1 and normally expressed in patterns that correlate with REV and KAN1. Our data reveal that a significant number of genes responsive to REV are regulated in opposite ways depending on time after induction, with genes associated with auxin response and synthesis upregulated initially, but later repressed. We also characterize the cell type specific expression patterns of auxin responsive genes and identify a set of genes involved in organogenesis repressed by both REV and KAN1.
PMID: 32294082
J Integr Plant Biol , IF:4.885 , 2020 Apr doi: 10.1111/jipb.12931
SHY2 as a node in the regulation of root meristem development by auxin, brassinosteroids, and cytokinin.
Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, China.; School of Life Science and Engineering, Henan University of Urban Construction, Pingdingshan, 467044, China.; Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang, 621000, China.
In multicellular organisms, the balance between cell division and differentiation determines organ size, and represents a central unknown in developmental biology. In Arabidopsis roots, this balance is mediated between cytokinin and auxin through a regulatory circuit converging on the IAA3/SHORT HYPOCOTYL 2 (SHY2) gene. Here, we show that crosstalk between brassinosteroids (BRs) and auxin occurs in the vascular transition zone to promote root meristem development. We found that BR increases root meristem size by up-regulating expression of the PINFORMED 7 (PIN7) gene and down-regulating expression of the SHY2 gene. In addition, BES1 could directly bind to the promoter regions of both PIN7 and SHY2, indicating that PIN7 and SHY2 mediate the BR-induced growth of the root meristem by serving as direct targets of BES1. Moreover, the PIN7 overexpression and loss-of-function SHY2 mutant were sensitive to the effects of BR and could partially suppress the short-root phenotypes associated with deficient BR signaling. Interestingly, BRs could inhibit the accumulation of SHY2 protein in response to cytokinin. Taken together, these findings suggest that a complex equilibrium model exists in which regulatory interactions among BRs, auxin, and cytokinin regulate optimal root growth.
PMID: 32239656
Ecotoxicol Environ Saf , IF:4.872 , 2020 Apr , V192 : P110285 doi: 10.1016/j.ecoenv.2020.110285
Gamma-aminobutyric acid enhances tolerance to iron deficiency by stimulating auxin signaling in cucumber (Cucumis sativusL.).
College of Horticulture, Henan Agricultural University, Zhengzhou, 450002, PR China.; College of Horticulture, Henan Agricultural University, Zhengzhou, 450002, PR China. Electronic address: piao1203@163.com.
Iron deficiency severely affects crop yield and quality. Gamma-aminobutyric acid (GABA) plays a vital role in plant responses to multifarious stresses. However, the role of GABA in Fe deficiency responses and the potential mechanisms remain largely unknown in cucumber. Here, we found that Fe deficiency raised the GABA levels in leaves and roots of cucumber. To probe the role of GABA in Fe deficiency, the seedlings were subjected to five levels of GABA concentrations (0, 5, 10, 20 and 40 mmol L(-1)) for 7 days under Fe deficiency. The results demonstrated that 20 mM GABA in alleviating the Fe deficiency-induced stress was the most effective. GABA pretreatment reduced the Fe deficiency-induced chlorosis and inhibition of photosynthesis and growth, and significantly enhanced the contents of iron in shoots and roots. Exogenous GABA significantly decreased the pH of nutrient solution and increased ferric-chelate reductase (FCR) activity induced by Fe deficiency and the transcript levels of Fe uptake-related genes HA1, FRO2 and IRT1 in roots. GABA also increased the content of auxin (IAA) and expression of auxin biosynthesis (YUC4), response (IAA1), and transport (PIN1) genes under Fe deficiency. Furthermore, exogenous the auxin transport inhibitor 1-naphthylphthalamic acid (NPA) application abolished the GABA-induced changes in Fe deficiency. In summary, we found that GABA improves tolerance to iron deficiency via an auxin-dependent mechanism in cucumber.
PMID: 32035398
Int J Mol Sci , IF:4.556 , 2020 Apr , V21 (8) doi: 10.3390/ijms21082880
Signalling Overlaps between Nitrate and Auxin in Regulation of The Root System Architecture: Insights from the Arabidopsis thaliana.
Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China.; Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Nitrate (NO3(-)) and auxin are key regulators of root growth and development, modulating the signalling cascades in auxin-induced lateral root formation. Auxin biosynthesis, transport, and transduction are significantly altered by nitrate. A decrease in nitrate (NO3(-)) supply tends to promote auxin translocation from shoots to roots and vice-versa. This nitrate mediated auxin biosynthesis regulating lateral roots growth is induced by the nitrate transporters and its downstream transcription factors. Most nitrate responsive genes (short-term and long-term) are involved in signalling overlap between nitrate and auxin, thereby inducing lateral roots initiation, emergence, and development. Moreover, in the auxin signalling pathway, the varying nitrate supply regulates lateral roots development by modulating the auxin accumulation in the roots. Here, we focus on the roles of nitrate responsive genes in mediating auxin biosynthesis in Arabidopsis root, and the mechanism involved in the transport of auxin at different nitrate levels. In addition, this review also provides an insight into the significance of nitrate responsive regulatory module and their downstream transcription factors in root system architecture in the model plant Arabidopsis thaliana.
PMID: 32326090
Int J Mol Sci , IF:4.556 , 2020 Apr , V21 (8) doi: 10.3390/ijms21082784
Formation of the Secondary Abscission Zone Induced by the Interaction of Methyl Jasmonate and Auxin in Bryophyllum calycinum: Relevance to Auxin Status and Histology.
Research Institute of Horticulture, Konstytucji 3 Maja 1/3, 96-100 Skierniewice, Poland.; The Franciszek Gorski Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, 30-239 Krakow, Poland.; Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.; Faculty of Liberal Arts and Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
The interaction of methyl jasmonate (JA-Me) and indole-3-acetic acid (IAA) to induce the formation of the secondary abscission zone in the middle of internode segments of Bryophyllum calycinum was investigated in relation to auxin status and histology. When IAA at 0.1% (w/w, in lanolin) was applied to the segments, the formation of the secondary abscission zone at a few mm above the treatment in the apical direction was observed. On the contrary, IAA at 0.5% (w/w, in lanolin) did not induce the formation of the secondary abscission zone. JA-Me at 0.5% (w/w, in lanolin) applied to the middle of internode segments kept in the normal (natural) or inverted positions also induced the formation of the secondary abscission zone below and above parts of the treatment. IAA at 0.5% applied to the cut surface of the upper part of the segments completely prevented the formation of the secondary abscission zone induced by JA-Me. Simultaneous application of IAA 0.5% with JA-Me 0.5% in the middle part of the internode segments induced the formation of the secondary abscission zone at 10 mm to 12 mm above the treatment. Histological analyses indicated that the formation of the secondary abscission zone was characterized by the presence of newly synthesized cell plates that resulted from periclinal cell division within one layer of mother cells in stems. The effects of IAA (0.1%) and JA-Me (0.5%) on the formation of the secondary abscission zone were histologically similar. Comprehensive analyses of plant hormones revealed that the balance of the endogenous levels of IAA in both sides adjacent to the abscission zone was significantly disturbed when the secondary abscission formation was induced by the application of IAA. These results strongly suggest that an auxin gradient is important in the formation of the secondary abscission zone in the internode segments of B. calycinum, and IAA gradient results from polar IAA transport from the application site. IAA is important in the regulation of formation of the secondary abscission zone induced by JA-Me. Further possible mechanisms of the formation of the secondary abscission zone in the internode segments of B. calycinum are also discussed in the interaction of JA-Me and IAA.
PMID: 32316348
Int J Mol Sci , IF:4.556 , 2020 Apr , V21 (7) doi: 10.3390/ijms21072567
Chlorinated Auxins-How Does Arabidopsis Thaliana Deal with Them?
Institute of Botany, Technische Universitat Dresden, 01062 Dresden, Germany.; Department of Natural Product Synthesis, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany.; Faculty of Chemistry and Food Chemistry, Technische Universitat Dresden, 01062 Dresden, Germany.
Plant hormones have various functions in plants and play crucial roles in all developmental and differentiation stages. Auxins constitute one of the most important groups with the major representative indole-3-acetic acid (IAA). A halogenated derivate of IAA, 4-chloro-indole-3-acetic acid (4-Cl-IAA), has previously been identified in Pisum sativum and other legumes. While the enzymes responsible for the halogenation of compounds in bacteria and fungi are well studied, the metabolic pathways leading to the production of 4-Cl-IAA in plants, especially the halogenating reaction, are still unknown. Therefore, bacterial flavin-dependent tryptophan-halogenase genes were transformed into the model organism Arabidopsis thaliana. The type of chlorinated indole derivatives that could be expected was determined by incubating wild type A. thaliana with different Cl-tryptophan derivatives. We showed that, in addition to chlorinated IAA, chlorinated IAA conjugates were synthesized. Concomitantly, we found that an auxin conjugate synthetase (GH3.3 protein) from A. thaliana was able to convert chlorinated IAAs to amino acid conjugates in vitro. In addition, we showed that the production of halogenated tryptophan (Trp), indole-3-acetonitrile (IAN) and IAA is possible in transgenic A. thaliana in planta with the help of the bacterial halogenating enzymes. Furthermore, it was investigated if there is an effect (i) of exogenously applied Cl-IAA and Cl-Trp and (ii) of endogenously chlorinated substances on the growth phenotype of the plants.
PMID: 32272759
Physiol Plant , IF:4.148 , 2020 Apr , V168 (4) : P893-908 doi: 10.1111/ppl.13029
Homeotic transformation from stamen to petal in Eriobotrya japonica is associated with hormone signal transduction and reduction of the transcriptional activity of EjAG.
Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China.; Academy of Agricultural Sciences of Southwest University, State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Chongqing, China.
Double-flower loquat (Eriobotrya japonica) is a new germplasm with homeotic transformation of stamen into petal in whorl 3. However, little information is available on the molecular mechanism of this transformation. Herein, we analyzed the transcriptome, candidate genes and endogenous hormones to investigate the mechanisms underlying this homeotic transformation. Some transcription factors, such as MADS-box, TCP and MYB, were significantly differentially expressed. Importantly, we confirmed that one of these (DN39625_c0_g1), which encoded a C-class floral homeotic protein referred to as AGAMOUS ortholog (EjAG), was significantly downregulated. Subcellular localization of EjAG was found to be in the nucleus. Ectopic expression of EjAG rescued the development of stamens and carpels from the double-flower phenotype in an Arabidopsis ag mutant, suggesting that EjAG expression is associated with double-flower formation. Meanwhile, enrichment analyses showed that the differentially expressed genes (DEGs) were mainly involved in the metabolic pathways of hormone signal transduction. The DEGs of auxin, gibberellin A (GA) and cytokinin signaling pathways were mainly upregulated. However, the DEGs of abscisic acid (ABA) and the ethylene signaling pathway were mainly downregulated. Accordingly, the concentrations of indoleacetic acid, kinetin and GA3 were high at the petaloid stamen stage, but the ABA concentration remained low. The identified genes and pathways provide abundant sequence resources for studying the mechanisms underlying the homeotic transformation in loquat and other Rosaceae species.
PMID: 31587280
Physiol Plant , IF:4.148 , 2020 Apr , V168 (4) : P845-875 doi: 10.1111/ppl.13026
Histology, histochemistry and ultrastructure of pre-embryogenic cells determined for direct somatic embryogenesis in the palm tree Syagrus oleracea.
Department of Forest Engineering, University of Brasilia, Brasilia, DF, Brazil.; Laboratory of Plant Tissue Culture II, Embrapa Genetic Resources and Biotechnology, Brasilia, DF, Brazil.; Department of Cell Biology, University of Brasilia, Brasilia, DF, Brazil.; Laboratory of Bioimaging and Microscopy, Embrapa Genetic Resources and Biotechnology, Brasilia, DF, Brazil.
Somatic embryogenesis in palm trees is, in general, a slow and highly complex process, with a predominance of the indirect route and, consequently, a lack of knowledge about the direct route. We present new knowledge related to the morphological, histochemical and ultrastructural aspects of the transition from somatic to embryogenic cells and direct formation of somatic embryos from mature zygotic embryos of Syagrus oleracea, a palm tree. The results support the general concept that 2,4-dichlorophenoxyacetic acid plays a critical role for the formation of somatic embryos of direct and multicellular origin. Seven days in medium with auxin were enough for the identification of embryogenic cells. These cells had a set of characteristics corresponding to totipotent stem cells. At 14 days on induction medium, nodular formations were observed in the distal region of inoculated embryos, which evolved into globular somatic embryos. At 120 days on induction medium, the quality of the somatic embryos was compromised. The dynamics of the mobilization of reserve compounds was also demonstrated, with emphasis on starch and protein as energy sources required for the embryogenic process. This study shows for the first time the anatomical and ultrastructural events involved in direct somatic embryogenesis in a palm tree and incites the scientific community to return to the discussion of classical concepts related to direct somatic embryogenesis, especially regarding the characteristics and location of determined pre-embryogenic cells.
PMID: 31517991
Biomolecules , IF:4.082 , 2020 Apr , V10 (4) doi: 10.3390/biom10040663
Bioconversion of Biologically Active Indole Derivatives with Indole-3-Acetic Acid-Degrading Enzymes from Caballeronia glathei DSM50014.
Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio al. 7, LT-10257 Vilnius, Lithuania.
A plant auxin hormone indole-3-acetic acid (IAA) can be assimilated by bacteria as an energy and carbon source, although no degradation has been reported for indole-3-propionic acid and indole-3-butyric acid. While significant efforts have been made to decipher the Iac (indole-3-acetic acid catabolism)-mediated IAA degradation pathway, a lot of questions remain regarding the mechanisms of individual reactions, involvement of specific Iac proteins, and the overall reaction scheme. This work was aimed at providing new experimental evidence regarding the biodegradation of IAA and its derivatives. Here, it was shown that Caballeronia glathei strain DSM50014 possesses a full iac gene cluster and is able to use IAA as a sole source of carbon and energy. Next, IacE was shown to be responsible for the conversion of 2-oxoindole-3-acetic acid (Ox-IAA) intermediate into the central intermediate 3-hydroxy-2-oxindole-3-acetic acid (DOAA) without the requirement for IacB. During this reaction, the oxygen atom incorporated into Ox-IAA was derived from water. Finally, IacA and IacE were shown to convert a wide range of indole derivatives, including indole-3-propionic acid and indole-3-butyric acid, into corresponding DOAA homologs. This work provides novel insights into Iac-mediated IAA degradation and demonstrates the versatility and substrate scope of IacA and IacE enzymes.
PMID: 32344740
Plant Cell Physiol , IF:4.062 , 2020 Apr doi: 10.1093/pcp/pcaa046
Life-course monitoring of endogenous phytohormone levels under field conditions reveals diversity of physiological states among barley accessions.
Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama, Japan.; RIKEN Center for Sustainable Resource Science, 1-7-22 Suehirocho, Tsurumiku, Yokohama, Kanagawa, Japan.; Kihara Institute for Biological Research, Yokohama City University, 641-12 Maiokacho, Totsukaku, Yokohama, Kanagawa, Japan.
Agronomically important traits often develop during the later stages of crop growth as consequences of various plant-environment interactions. Therefore, the temporal physiological states that change and accumulate during the crop's life course can significantly affect the eventual phenotypic differences in agronomic traits among crop varieties. Thus, to improve productivity, it is important to elucidate the associations between temporal physiological responses during the growth of different crop varieties and their agronomic traits. However, data representing the dynamics and diversity of physiological states in plants grown under field conditions is sparse. In this study, we quantified the endogenous levels of five phytohormones-auxin, cytokinins, abscisic acid, jasmonate, and salicylic acid-in the leaves of eight diverse barley (Hordeum vulgare) accessions grown under field conditions sampled weekly over their life course to assess the ongoing fluctuations in hormone levels in the different accessions under field growth conditions. Notably, we observed enormous changes over time in the development-related plant hormones, such as auxin and cytokinins. Using 3' RNA-seq-based transcriptome data from the same samples, we investigated the expression of barley genes orthologous to known hormone-related genes of Arabidopsis throughout the life course. These data illustrated the dynamics and diversity of the physiological states of these field-grown barley accessions. Together our findings provide new insights into plant-environment interaction, highlighting that there is cultivar diversity in physiological responses during growth under field conditions.
PMID: 32294217
Plant Cell Physiol , IF:4.062 , 2020 Apr , V61 (4) : P685-698 doi: 10.1093/pcp/pcaa014
Redox-Responsive Transcription Factor 1 (RRFT1) Is Involved in Extracellular ATP-Regulated Arabidopsis thaliana Seedling Growth.
Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, Hebei, China.; College of Pharmacy, Hebei University of Chinese Medicine, Shijiazhuang 050200, Hebei, China.; Department of Chemistry Engineering and Biological Technology, Xingtai University, Xingtai 054001, Hebei, China.
Extracellular adenosine triphosphate (eATP) is an apoplastic signaling molecule that plays an essential role in the growth and development of plants. Arabidopsis seedlings have been reported to respond to eATP; however, the downstream signaling components are still not well understood. In this study, we report that an ethylene-responsive factor, Redox-Responsive Transcription Factor 1 (RRTF1), is involved in eATP-regulated Arabidopsis thaliana seedling growth. Exogenous adenosine triphosphate inhibited green seedling root growth and induced hypocotyl bending of etiolated seedlings. RRTF1 loss-of-function mutant (rrtf1) seedlings showed decreased responses to eATP, while its complementation or overexpression led to recovered or increased eATP responsiveness. RRTF1 was expressed rapidly after eATP stimulation and then migrated into the nuclei of root tip cells. eATP-induced auxin accumulation in root tip or hypocotyl cells was impaired in rrtf1. Chromatin immunoprecipitation and high-throughput sequencing results indicated that eATP induced some genes related to cell growth and development in wild type but not in rrtf1 cells. These results suggest that RRTF1 may be involved in eATP signaling by regulating functional gene expression and cell metabolism in Arabidopsis seedlings.
PMID: 32049334
Plant Cell Physiol , IF:4.062 , 2020 Apr , V61 (4) : P838-850 doi: 10.1093/pcp/pcaa008
Rhizotaxis Modulation in Arabidopsis Is Induced by Diffusible Compounds Produced during the Cocultivation of Arabidopsis and the Endophytic Fungus Serendipita indica.
Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, 599-8531 Japan.; College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu Shiga, 525-8577 Japan.; Graduate School of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529 Japan.; Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529 Japan.; Julius-von-Sachs-Institute, Pharmaceutical Biology, Julius-Maximilians-University Wurzburg, Julius-von-Sachs-Platz 2, Wurzburg D-97082, Germany.; Bioeconomy Research Institute, Research Center for the 21st Century, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, 599-8531 Japan.
Rhizotaxis is established under changing environmental conditions via periodic priming of lateral root (LR) initiation at the root tips and adaptive LR formation along the primary root (PR). In contrast to the adaptable LR formation in response to nutrient availability, there is little information on root development during interactions with beneficial microbes. The Arabidopsis root system is characteristically modified upon colonization by the root endophytic fungus Serendipita indica, accompanied by a marked stimulation of LR formation and the inhibition of PR growth. This root system modification has been attributed to endophyte-derived indole-3-acetic acid (IAA). However, it has yet to be clearly explained how fungal IAA affects the intrinsic LR formation process. In this study, we show that diffusible compounds (chemical signals) other than IAA are present in the coculture medium of Arabidopsis and S. indica and induce auxin-responsive DR5::GUS expression in specific sections within the pericycle layer. The DR5::GUS expression was independent of polar auxin transport and the major IAA biosynthetic pathways, implicating unidentified mechanisms responsible for the auxin response and LR formation. Detailed metabolite analysis revealed the presence of multiple compounds that induce local auxin responses and LR formation. We found that benzoic acid (BA) cooperatively acted with exogenous IAA to generate a local auxin response in the pericycle layer, suggesting that BA is one of the chemical signals involved in adaptable LR formation. Identification and characterization of the chemical signals will contribute to a greater understanding of the molecular mechanisms underlying adaptable root development and to unconventional technologies for sustainable agriculture.
PMID: 32016405
Ann Bot , IF:4.005 , 2020 Apr , V125 (5) : P821-832 doi: 10.1093/aob/mcz173
Plasma membrane receptor-like kinases and transporters are associated with 2,4-D resistance in wild radish.
Australian Herbicide Resistance Initiative, School of Agriculture and Environment, University of Western Australia, Crawley, Australia.; Proteomics International, Nedlands, Australia.
BACKGROUND AND AIMS: Resistance to the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) in wild radish (Raphanus raphanistrum) appears to be due to a complex, multifaceted mechanism possibly involving enhanced constitutive plant defence and alterations in auxin signalling. Based on a previous gene expression analysis highlighting the plasma membrane as being important for 2,4-D resistance, this study aimed to identify the components of the leaf plasma membrane proteome that contribute to resistance. METHODS: Isobaric tagging of peptides was used to compare the plasma membrane proteomes of a 2,4-D-susceptible and a 2,4-D-resistant wild radish population under control and 2,4-D-treated conditions. Eight differentially abundant proteins were then targeted for quantification in the plasma membranes of 13 wild radish populations (two susceptible, 11 resistant) using multiple reaction monitoring. KEY RESULTS: Two receptor-like kinases of unknown function (L-type lectin domain-containing receptor kinase IV.1-like and At1g51820-like) and the ATP-binding cassette transporter ABCB19, an auxin efflux transporter, were identified as being associated with auxinic herbicide resistance. The variability between wild radish populations suggests that the relative contributions of these candidates are different in the different populations. CONCLUSIONS: To date, no receptor-like kinases have been reported to play a role in 2,4-D resistance. The lectin-domain-containing kinase may be involved in perception of 2,4-D at the plasma membrane, but its ability to bind 2,4-D and the identity of its signalling partner(s) need to be confirmed experimentally. ABCB19 is known to export auxinic compounds, but its role in 2,4-D resistance in wild radish appears to be relatively minor.
PMID: 31646341
Ann Bot , IF:4.005 , 2020 Apr , V125 (5) : P805-819 doi: 10.1093/aob/mcz160
The SAUR41 subfamily of SMALL AUXIN UP RNA genes is abscisic acid inducible to modulate cell expansion and salt tolerance in Arabidopsis thaliana seedlings.
Institute of Genetics and Regenerative Biology, College of Life Sciences, Zhejiang University, Hangzhou, China.
BACKGROUND AND AIMS: Most primary auxin response genes are classified into three families: AUX/IAA, GH3 and SAUR genes. Few studies have been conducted on Arabidopsis thaliana SAUR genes, possibly due to genetic redundancy among different subfamily members. Data mining on arabidopsis transcriptional profiles indicates that the SAUR41 subfamily members of SMALL AUXIN UP RNA genes are, strikingly, induced by an inhibitory phytohormone, abscisic acid (ABA). We aimed to reveal the physiological roles of arabidopsis SAUR41 subfamily genes containing SAUR40, SAUR41, SAUR71 and SAUR72. METHODS: Transcriptional responses of arabidopsis SAUR41 genes to phytohormones were determined by quantitative real-time PCR. Knock out of SAUR41 genes was carried out with the CRISPR/Cas9 (clustered regulatory interspaced short palindromic repeats/CRISPR-associated protein 9) genome editing technique. The saur41/40/71/72 quadruple mutants, SAUR41 overexpression lines and the wild type were subjected to ultrastructural observation, transcriptome analysis and physiological characterization. KEY RESULTS: Transcription of arabidopsis SAUR41 subfamily genes is activated by ABA but not by gibberellic acids and brassinosteroids. Quadruple mutations in saur41/40/71/72 led to reduced cell expansion/elongation in cotyledons and hypocotyls, opposite to the overexpression of SAUR41; however, an irregular arrangement of cell size and shape was observed in both cases. The quadruple mutants had increased transcription of calcium homeostasis/signalling genes in seedling shoots, and the SAUR41 overexpression lines had decreased transcription of iron homeostasis genes in roots and increased ABA biosynthesis in shoots. Notably, both the quadruple mutants and the SAUR41 overexpression lines were hypersensitive to salt stress during seedling establishment, whereas specific expression of SAUR41 under the ABA-responsive RD29A (Responsive to Desiccation 29A) promoter in the quadruple mutants rescued the inhibitory effect of salt stress. CONCLUSIONS: The SAUR41 subfamily genes of arabidopsis are ABA inducible to modulate cell expansion, ion homeostasis and salt tolerance. Our work may provide new candidate genes for improvement of plant abiotic stress tolerance.
PMID: 31585004
Sci Rep , IF:3.998 , 2020 Apr , V10 (1) : P6051 doi: 10.1038/s41598-020-62962-4
Opposing influences of TAC1 and LAZY1 on Lateral Shoot Orientation in Arabidopsis.
Department of Horticulture, Michigan State University, East Lansing, MI, 48824, USA. chollend@msu.edu.; Department of Horticulture, Michigan State University, East Lansing, MI, 48824, USA.; USDA-ARS Appalachian Fruit Research Station, Kearneysville, WV, 25430, USA.; Washington State University Tree Fruit Research and Extension Center, Wenatchee, WA, 98801, USA.
TAC1 and LAZY1 are members of a gene family that regulates lateral shoot orientation in plants. TAC1 promotes outward orientations in response to light, while LAZY1 promotes upward shoot orientations in response to gravity via altered auxin transport. We performed genetic, molecular, and biochemical assays to investigate possible interactions between these genes. In Arabidopsis they were expressed in similar tissues and double mutants revealed the wide-angled lazy1 branch phenotype, indicating it is epistatic to the tac1 shoot phenotype. Surprisingly, the lack of TAC1 did not influence gravitropic shoot curvature responses. Combined, these results suggest TAC1 might negatively regulate LAZY1 to promote outward shoot orientations. However, additional results revealed that TAC1- and LAZY1 influence on shoot orientation is more complex than a simple direct negative regulatory pathway. Transcriptomes of Arabidopsis tac1 and lazy1 mutants compared to wild type under normal and gravistimulated conditions revealed few overlapping differentially expressed genes. Overexpression of each gene did not result in major branch angle differences. Shoot tip hormone levels were similar between tac1, lazy1, and Col, apart from exceptionally elevated levels of salicylic acid in lazy1. The data presented here provide a foundation for future study of TAC1 and LAZY1 regulation of shoot architecture.
PMID: 32269265
Sci Rep , IF:3.998 , 2020 Apr , V10 (1) : P5855 doi: 10.1038/s41598-020-62725-1
Prescience of endogenous regulation in Arabidopsis thaliana by Pseudomonas putida MTCC 5279 under phosphate starved salinity stress condition.
Division of Microbial Technology, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226 001, India.; Academy of Scientific and Innovative Research, AcSIR, Ghaziabad, 201002, India.; Division of Microbial Technology, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226 001, India. ssnbri@gmail.com.; Academy of Scientific and Innovative Research, AcSIR, Ghaziabad, 201002, India. ssnbri@gmail.com.
Phosphorus (P) availability and salinity stress are two major constraints for agriculture productivity. A combination of salinity and P starvation is known to be more deleterious to plant health. Plant growth promoting rhizobacteria are known to ameliorate abiotic stress in plants by increasing the availability of different nutrients. However, interaction mechanisms of plant grown under salinity and P stress condition and effect of beneficial microbe for stress alleviation is still obscure. Earlier we reported the molecular insight of auxin producing, phosphate solubilising Pseudomonas putida MTCC 5279 (RAR) mediated plant growth promotion in Arabidopsis thaliana. In present study new trait of proline and phosphatase production of RAR and its impact on modulation of physiological phenomenon under phosphate starved-salinity stress condition in A. thaliana has been investigated. Different physiological and molecular determinants under RAR- A. thaliana interaction showed that auxin producing RAR shows tryptophan dependence for growth and proline production in ATP dependant manner under salinity stress. However, under P deprived conditions growth and proline production are independent of tryptophan. RAR mediated lateral root branching and root hair density through modulation of abscisic acid signalling was observed. Acidic phosphatase activity under P starved and salinity stress condition was majorly modulated along with ROS metabolism and expression of stress responsive/phosphate transporter genes. A strong correlation of different morpho-physiological factor with RAR + salt conditions, showed We concluded that enhanced adverse effect of salinity with unavailability of P was dampened in presence of P. putida MTCC 5279 (RAR) in A. thaliana, though more efficiently salinity stress conditions. Therefore, alleviation of combined stress of salinity induced phosphate nutrient deficiency by inoculation of beneficial microbe, P. putida MTCC 5279 offer good opportunities for enhancing the agricultural productivity.
PMID: 32246044
Plant Cell Rep , IF:3.825 , 2020 Apr , V39 (4) : P543-552 doi: 10.1007/s00299-020-02510-6
The BIG gene controls size of shoot apical meristems in Arabidopsis thaliana.
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, Shandong, China.; State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, Shandong, China. suyh@sdau.edu.cn.; State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, Shandong, China. tangliping163@163.com.
KEY MESSAGE: BIG regulates the shoot stem cell population. The shoot apical meristem (SAM) contains a population of self-renewing cells, and provides daughter cells for initiation and development of aerial parts of plants. However, the underlying mechanisms of SAM size regulation remain largely unclear. Here, we identified a mutant that displayed a large SAM, designated big-shoot meristem (big-m), in Arabidopsis thaliana. The phenotype of big-m is caused by a new T-DNA insertion allele of BIG, causing a loss of function. The big-m mutant had more stem cells in the SAM than in the wild type. Expression of WUSCHEL (WUS) and SHOOTMERISTEMLESS (STM) was promoted in big-m compared with the wild type, showing that BIG functions upstream of WUS and STM. Therefore, BIG is an important regulator of the stem cell population in the SAM. Furthermore, genetic analysis indicated that BIG acts synergistically with PIN-FORMED1 (PIN1) in controlling SAM size. Our results suggest that BIG plays an important role in controlling Arabidopsis thaliana SAM growth via PIN1-mediated auxin homeostasis.
PMID: 32025802
Plant Cell Rep , IF:3.825 , 2020 Apr , V39 (4) : P473-487 doi: 10.1007/s00299-019-02503-0
Non-intrinsic ATP-binding cassette proteins ABCI19, ABCI20 and ABCI21 modulate cytokinin response at the endoplasmic reticulum in Arabidopsis thaliana.
Department of Life Science, POSTECH, Pohang, 37673, Republic of Korea.; Section of Cell and Developmental Biology, University of California, San Diego, San Diego, CA, USA.; Department of Biotechnology, School of Engineering and Applied Sciences, Bennett University, Greater Noida, India.; Division of Integrative Bioscience and Biotechnology, POSTECH, Pohang, 37673, Republic of Korea.; Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.; Division of Integrative Bioscience and Biotechnology, POSTECH, Pohang, 37673, Republic of Korea. ylee@postech.ac.kr.
KEY MESSAGE: The non-intrinsic ABC proteins ABCI20 and ABCI21 are induced by light under HY5 regulation, localize to the ER, and ameliorate cytokinin-driven growth inhibition in young Arabidopsis thaliana seedlings. The plant ATP-binding cassette (ABC) I subfamily (ABCIs) comprises heterogeneous proteins containing any of the domains found in other ABC proteins. Some ABCIs are known to function in basic metabolism and stress responses, but many remain functionally uncharacterized. ABCI19, ABCI20, and ABCI21 of Arabidopsis thaliana cluster together in a phylogenetic tree, and are suggested to be targets of the transcription factor ELONGATED HYPOCOTYL 5 (HY5). Here, we reveal that these three ABCIs are involved in modulating cytokinin responses during early seedling development. The ABCI19, ABCI20 and ABCI21 promoters harbor HY5-binding motifs, and ABCI20 and ABCI21 expression was induced by light in a HY5-dependent manner. abci19 abci20 abci21 triple and abci20 abci21 double knockout mutants were hypersensitive to cytokinin in seedling growth retardation assays, but did not show phenotypic differences from the wild type in either control medium or auxin-, ABA-, GA-, ACC- or BR-containing media. ABCI19, ABCI20, and ABCI21 were expressed in young seedlings and the three proteins interacted with each other, forming a large protein complex at the endoplasmic reticulum (ER) membrane. These results suggest that ABCI19, ABCI20, and ABCI21 fine-tune the cytokinin response at the ER under the control of HY5 at the young seedling stage.
PMID: 32016506
Plant Cell Rep , IF:3.825 , 2020 Apr , V39 (4) : P527-541 doi: 10.1007/s00299-020-02508-0
Hormonal and gene dynamics in de novo shoot meristem formation during adventitious caulogenesis in cotyledons of Pinus pinea.
Instituto Universitario de Biotecnologia de Asturias, Departamento de Biologia de Organismos y Sistemas, Universidad de Oviedo, Oviedo, Spain.; Servicio Regional de Investigacion Y Desarrollo Agroalimentario de Asturias (SERIDA), Villaviciosa, Spain.; Instituto Universitario de Biotecnologia de Asturias, Departamento de Biologia de Organismos y Sistemas, Universidad de Oviedo, Oviedo, Spain. rordas@uniovi.es.
KEY MESSAGE: Several members of WOX and KNOX gene families and several plant growth regulators, basically cytokinins and auxins, play a key role during adventitious caulogenesis in the conifer Pinus pinea. Similar to Arabidopsis thaliana, Pinus pinea shoot organogenesis is a multistep process. However, there are key differences between both species, which may alter the underlying physiological and genetic programs. It is unknown if the genic expression models during angiosperm development may be applicable to conifers. In this work, an analysis of the endogenous content of different plant growth regulators and the expression of genes putatively involved in adventitious caulogenesis in P. pinea cotyledons was conducted. A multivariate analysis of both datasets was also realized through partial least squares regression and principal component analysis to obtain an integral vision of the mechanisms involved in caulogenesis in P. pinea. Analyses show that cotyledons cultured in the presence of benzyladenine during long times (2-6 days) cluster separately from the rest of the samples, suggesting that the benzyladenine increase observed during the first hours of culture is sufficient to trigger the caulogenic response through the activation of specific developmental programs. In particular, the most relevant factors involved in this process are the cytokinins trans-zeatin, dihydrozeatin, trans-zeatin riboside and isopentenyl adenosine; the auxin indoleacetic acid; and the genes PpWUS, PpWOX5, PpKN2, PpKN3 and PipiRR1. WUS is functional in pines and has an important role in caulogenesis. Interestingly, WOX5 also seems to participate in the process, although its specific role has not been determined.
PMID: 31993729
Pest Manag Sci , IF:3.75 , 2020 Apr , V76 (4) : P1195-1204 doi: 10.1002/ps.5660
Quinclorac resistance in Echinochloa phyllopogon is associated with reduced ethylene synthesis rather than enhanced cyanide detoxification by beta-cyanoalanine synthase.
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan.; Plant Genome Engineering Research Unit, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, Japan.; Institute of Crop Science and Institute of Bioinformatics, Zhejiang University, Hangzhou, China.; Central Region Agricultural Research Center, National Agriculture and Food Research Organization, Tsu, Japan.; Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
BACKGROUND: Multiple herbicide resistant Echinochloa phyllopogon exhibits resistance to the auxin herbicide quinclorac. Previous research observed enhanced activity of the cyanide-detoxifying enzyme beta-cyanoalanine synthase (beta-CAS) and reduced ethylene production in the resistant line, suggesting beta-CAS-mediated cyanide detoxification and insensitivity to quinclorac stimulation as the resistance mechanisms. To investigate the molecular mechanisms of quinclorac resistance, we characterized the beta-CAS genes alongside plant transformation studies. The association of beta-CAS activity and ethylene production to quinclorac resistance was assayed in the F6 progeny of susceptible and resistant lines of E. phyllopogon. RESULTS: A single nucleotide polymorphism in a beta-CAS1 intron deleted aberrantly spliced mRNAs and enhanced beta-CAS activity in the resistant line. The enhanced activity, however, was not associated with quinclorac resistance in F6 lines. The results were supported by lack of quinclorac resistance in Arabidopsis thaliana expressing E. phyllopogon beta-CAS1 and no difference in quinclorac sensitivity between beta-CAS knockout and wild-type rice. Reduced ethylene production co-segregated with quinclorac resistance in F6 lines which were previously characterized to be resistant to other herbicides by an enhanced metabolism. CONCLUSION: beta-CAS does not participate in quinclorac sensitivity in E. phyllopogon. Our results suggest that a mechanism(s) leading to reduced ethylene production is behind the resistance. (c) 2019 Society of Chemical Industry.
PMID: 31659851
Plant Physiol Biochem , IF:3.72 , 2020 Apr , V152 : P1-11 doi: 10.1016/j.plaphy.2020.04.029
Transcriptome and metabolome analysis reveals regulatory networks and key genes controlling barley malting quality in responses to drought stress.
Agronomy Department, Zhejiang Key Lab of Crop Germplasm, Zhejiang University, Hangzhou, 310058, China.; Agronomy Department, Zhejiang Key Lab of Crop Germplasm, Zhejiang University, Hangzhou, 310058, China. Electronic address: zhanggp@zju.edu.cn.
Malting quality will be greatly deteriorated when barley plants suffer from post-anthesis drought stress, however there is a marked difference among barley genotypes in the responses of malting quality to drought stress, and the molecular mechanisms underlying the genotypic difference remain unclear. We made transcriptome and metabolome analysis on the developing grains of two barley genotypes differing in the responses to drought stress. Post-anthesis drought treatments led to decreased grain weight and beta-glucan content, increased grain protein content and beta-amylase activity. Drought stress enhanced H2O2 and heat-shock protein accumulation in the two barley genotypes, with the drought-tolerant genotype showing higher capacity of scavenging H2O2 and reducing misfolded protein accumulation than the drought-susceptible genotype. Moreover, the drought-tolerant genotype was more efficient in redistributing assimilates stored in the vegetative tissues into the developing grains. After re-watering to relieve drought stress, the drought-tolerant genotype can further modify auxin transport and ethylene signaling, enhancing redistribution of assimilates into grains. Transcriptome comparisons and weighted correlation network analysis (WGCNA) identified some key genes regulating the responses of malting quality traits to drought stress, such as RLK-LRR, beta-glucosidase and HSP . In conclusion, less change of main malting quality traits in the drought-tolerant genotype under post-anthesis drought stress is attributed to its higher capacity of alleviating the stress injury through scavenging ROS and redistributing the metabolites stored in the vegetative organs into the developing grains.
PMID: 32361397
Plant Physiol Biochem , IF:3.72 , 2020 Apr , V149 : P159-169 doi: 10.1016/j.plaphy.2020.02.004
OsNAR2.2 plays a vital role in the root growth and development by promoting nitrate uptake and signaling in rice.
Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing, 400030, PR China.; Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing, 400030, PR China. Electronic address: huangjunli@cqu.edu.cn.
Plants in soil faces great fluctuations of external mineral nutrient availability, and they have developed sophisticated nutrient sensing systems to regulate their physiological responses to prevent nutrient deficiency. However, complete knowledge of the regulatory system is required to maximize inorganic nitrogen (N) uptake and utilization. In this study, we report a partner protein for high-affinity nitrate transport, OsNAR2.2. OsNAR2.2 was involved in the root growth in a nitrate-dependent manner in rice, and this process was closely associated with auxin. Expression analysis showed that OsNAR2.2 responded to nitrate and various plant hormone signals. Knockdown of OsNAR2.2 by T-DNA insertion not only significantly repressed the primary root elongation, but also severely reduced the number of lateral root and adventitious root. Further research indicated that the size of meristematic zone and epidermal cell length of mature zone in the primary root tip were remarkably reduced, and the formation of lateral root primordial was constrained in osnar2.2 mutant. Interestingly, the repression of root growth in osnar2.2 mutant was observed when NO3(-) but not NH4(+) was used as N source in the medium. The NO3(-) content in osnar2.2 root was significantly reduced under NO3(-) conditions, in comparison with that of wild type. Meanwhile, the free IAA accumulation as well as the expression of auxin biosynthesis and transport genes was altered in osnar2.2 root, suggesting there might be a crosslink between the nitrate and auxin signaling. Together, OsNAR2.2 plays a vital role in rice root growth and development in a nitrate-dependent manner, which might be associated with auxin signaling.
PMID: 32070909
Mol Plant Microbe Interact , IF:3.696 , 2020 Apr , V33 (4) : P600-611 doi: 10.1094/MPMI-09-19-0250-R
Benzothiadiazole Conditions the Bean Proteome for Immunity to Bean Rust.
Soybean Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD, U.S.A.; Animal Biosciences and Biotechnology Laboratory, USDA-ARS, Beltsville, MD, U.S.A.
The common bean rust fungus reduces harvests of the dry, edible common bean. Natural resistance genes in the plant can provide protection until a fungal strain that breaks resistance emerges. In this study, we demonstrate that benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester (BTH) sprayed on susceptible beans induces resistance to common bean rust. Protection occurred as soon as 72 h after treatment and resulted in no signs of disease 10 days after inoculation with rust spores. By contrast, the susceptible control plants sustained heavy infections and died. To understand the effect BTH has on the bean proteome, we measured the changes of accumulation for 3,973 proteins using mass spectrometry. The set of 409 proteins with significantly increased accumulation in BTH-treated leaves included receptor-like kinases SOBIR1, CERK1, and LYK5, which perceive pathogens, and EDS1, a regulator of the salicylic acid defense pathway. Other proteins that likely contributed to resistance included pathogenesis-related proteins, a full complement of enzymes that catalyze phenylpropanoid biosynthesis, and protein receptors, transporters, and enzymes that modulate other defense responses controlled by jasmonic acid, ethylene, brassinosteroid, abscisic acid, and auxin. Increases in the accumulation of proteins required for vesicle-mediated protein secretion and RNA splicing occurred as well. By contrast, more than half of the 168 decreases belonged to chloroplast proteins and proteins involved in cell expansion. These results reveal a set of proteins needed for rust resistance and reaffirm the utility of BTH to control disease by amplifying the natural immune system of the bean plant.
PMID: 31999214
Plant Sci , IF:3.591 , 2020 Apr , V293 : P110416 doi: 10.1016/j.plantsci.2020.110416
TARGET OF RAPAMYCIN signaling plays a role in Arabidopsis growth promotion by Azospirillum brasilense Sp245.
Instituto de Investigaciones Quimico Biologicas, Universidad Michoacana de San Nicolas de Hidalgo, Ciudad Universitaria, Edif. A1 , Morelia, Michoacan CP 58040, Mexico.; Instituto de Investigaciones Quimico Biologicas, Universidad Michoacana de San Nicolas de Hidalgo, Ciudad Universitaria, Edif. A1 , Morelia, Michoacan CP 58040, Mexico. Electronic address: egpineda@umich.mx.
Azospirillum brasilense colonizes plant roots and improves productivity, but the molecular mechanisms behind its phytostimulation properties remain mostly unknown. Here, we uncover an important role of TARGET OF RAPAMYCIN (TOR) signaling on the response of Arabidopsis thaliana to A. brasilense Sp245. The effect of the bacterium on TOR expression was analyzed in the transgenic line TOR/tor-1, which carries a translational fusion with the GUS reporter protein, and the activity of TOR was assayed thought the phosphorylation of its downstream signaling target S6K protein. Besides, the role of TOR on plant growth in inoculated plants was assessed using the ATP-competitive inhibitor AZD-8055. A decrease in growth of the primary root correlates with an improved branching and absorptive capacity via lateral root and root hair proliferation 6 days after transplant to different concentrations of the bacterium (10(3) or 10(5) CFU/mL). Bacterization increased the expression of TOR in shoot and root apexes and promoted phosphorylation of S6K 3 days after transplant. The TOR inhibitor AZD-8055 (1 muM) inhibited plant growth and cell division in root meristems and in lateral root primordia, interfering with the phytostimulation by A. brasilense. In addition, the role of auxin produced by the bacterium to stimulate TOR expression was explored. Noteworthy, the A. brasilense mutant FAJ009, impaired in auxin production, was unable to elicit TOR signaling to the level observed for the wild-type strain, showing the importance of this phyhormone to stimulate TOR signaling. Together, our findings establish an important role of TOR signaling for the probiotic traits elicited by A. brasilense in A. thaliana.
PMID: 32081264
Plant Sci , IF:3.591 , 2020 Apr , V293 : P110414 doi: 10.1016/j.plantsci.2020.110414
Clathrin-mediated trafficking and PIN trafficking are required for auxin canalization and vascular tissue formation in Arabidopsis.
Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, Jagiellonska 28, 40-032 Katowice, Poland; Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, 62500 Brno, Czech Republic.; Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria.; Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, 62500 Brno, Czech Republic.; Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria. Electronic address: jiri.friml@ist.ac.at.
The flexible development of plants is characterized by a high capacity for post-embryonic organ formation and tissue regeneration, processes, which require tightly regulated intercellular communication and coordinated tissue (re-)polarization. The phytohormone auxin, the main driver for these processes, is able to establish polarized auxin transport channels, which are characterized by the expression and polar, subcellular localization of the PIN1 auxin transport proteins. These channels are demarcating the position of future vascular strands necessary for organ formation and tissue regeneration. Major progress has been made in the last years to understand how PINs can change their polarity in different contexts and thus guide auxin flow through the plant. However, it still remains elusive how auxin mediates the establishment of auxin conducting channels and the formation of vascular tissue and which cellular processes are involved. By the means of sophisticated regeneration experiments combined with local auxin applications in Arabidopsis thaliana inflorescence stems we show that (i) PIN subcellular dynamics, (ii) PIN internalization by clathrin-mediated trafficking and (iii) an intact actin cytoskeleton required for post-endocytic trafficking are indispensable for auxin channel formation, de novo vascular formation and vascular regeneration after wounding. These observations provide novel insights into cellular mechanism of coordinated tissue polarization during auxin canalization.
PMID: 32081263
Plant Sci , IF:3.591 , 2020 Apr , V293 : P110411 doi: 10.1016/j.plantsci.2020.110411
A recessive high-density pod mutant resource of Brassica napus.
Guizhou Rapeseed Institute, Guizhou Academy of Agricultural Sciences, Guiyang 550008, PR China; Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan 430062, PR China.; Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan 430062, PR China.; Guizhou Rapeseed Institute, Guizhou Academy of Agricultural Sciences, Guiyang 550008, PR China.; Hunan Provincial Key Laboratory of Phytohormones and Growth and Development, Hunan Agricultural University, Changsha 410128, PR China.; Guizhou Rapeseed Institute, Guizhou Academy of Agricultural Sciences, Guiyang 550008, PR China. Electronic address: xiangyangcell@126.com.
In Brassica napus, pod number and pod density are critical factors to determine seed yield. Although the pod density is an essential yield trait, the regulation of yield formation in oil crops, as well as the genetic and molecular mechanisms, are poorly understood. In this study, we characterized a rapeseed high-density pod mutant (dpt247) from composite hybridization. To shed some light on the nature of this mutation, it was investigated morphologically, anatomically, physiologically, genetically and transcriptomically. The mutant plant showed noticeable phenotypic differences in comparison with the control plant, including reduced plant height and primary branch length, decreased number of primary branches, significantly increased number of pod on the main inflorescence, and more compact pod distribution. Besides, the mutant had higher levels of indole-3-acetic acid (IAA) and zeatin riboside (ZR) in the shoot apical meristem (SAM). The dense pod trait was controlled by two major recessive genes identified in the segregating genetic populations of GRE501 and dpt247. RNA sequencing indicated genes participated in auxin, cytokinin and WUS/CLV signalling pathway in dpt247 were more active in the mutant. These results provide important information for understanding the regulation of yield formation and high yield breeding in rapeseed.
PMID: 32081260
Plant Sci , IF:3.591 , 2020 Apr , V293 : P110323 doi: 10.1016/j.plantsci.2019.110323
MYB94 and MYB96 additively inhibit callus formation via directly repressing LBD29 expression in Arabidopsis thaliana.
The Key Laboratory of the Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China.; The Key Laboratory of the Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China. Electronic address: xfn0990@sdu.edu.cn.; The Key Laboratory of the Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, China. Electronic address: http0528@163.com.
Plant somatic cells can be reprogrammed during in vitro culture. Callus induction is the initial step of a typical plant regeneration system. Recent studies showed that auxin-induced callus formation in multiple organs occurs from the pericycle or pericycle-like cells via a root developmental pathway. However, the molecular control of callus formation is largely unknown. Here, two MYB transcription factors, MYB94 and MYB96, were shown to play negative roles in auxin-induced callus formation in Arabidopsis. MYB94 and MYB96 were expressed in the newly formed callus. myb96, myb94, and myb94 myb96 generated more calli than the WT, with myb94 myb96 producing the most. MYB94 and MYB96 repressed expression of LATERAL ORGAN BOUNDARIES-DOMAIN 29 (LBD29) via directly binding to the gene's promoter. The loss of function of LBD29 partly rescued the callus formation defect of myb94 myb96. Our findings found MYB94 and MYB96 to be important repressors of callus formation and MYB94/96-LBD29 as a new regulatory pathway acting in parallel with ARF7/19-LBDs' pathway to modulate in vitro callus formation.
PMID: 32081254
BMC Plant Biol , IF:3.497 , 2020 Apr , V20 (1) : P182 doi: 10.1186/s12870-020-02398-0
Transcriptomic profiling and discovery of key genes involved in adventitious root formation from green cuttings of highbush blueberry (Vaccinium corymbosum L.).
Forestry and Pomology Research Insitute, Shanghai Academy of Agricultural Sciences, Jinqi Road No. 1000, Fengxian District, Shanghai, 201403, China.; Shanghai Key Lab of Protected Horticultural Technology, Shanghai Academy of Agricultural Sciences, Jinqi Road No. 1000, Fengxian District, Shanghai, 201403, China.; Forestry and Pomology Research Insitute, Shanghai Academy of Agricultural Sciences, Jinqi Road No. 1000, Fengxian District, Shanghai, 201403, China. jiangshuang@saas.sh.cn.; Shanghai Key Lab of Protected Horticultural Technology, Shanghai Academy of Agricultural Sciences, Jinqi Road No. 1000, Fengxian District, Shanghai, 201403, China. jiangshuang@saas.sh.cn.; Forestry and Pomology Research Insitute, Shanghai Academy of Agricultural Sciences, Jinqi Road No. 1000, Fengxian District, Shanghai, 201403, China. zhangxueying@saas.sh.cn.; Shanghai Key Lab of Protected Horticultural Technology, Shanghai Academy of Agricultural Sciences, Jinqi Road No. 1000, Fengxian District, Shanghai, 201403, China. zhangxueying@saas.sh.cn.
BACKGROUND: Propagation of cuttings is frequently used in various plant species, including blueberry, which shows special root characteristics that may hinder adventitious root (AR) formation. AR formation is influenced by various factors, and auxin is considered to play a central role; however, little is known of the related regulatory mechanisms. In this study, a comparative transcriptome analysis of green cuttings treated with or without indole-butyric acid (IBA) was performed via RNA_seq to identify candidate genes associated with IBA-induced AR formation. RESULTS: Rooting phenotypes, especially the rooting rate, were significantly promoted by exogenous auxin in the IBA application. Blueberry AR formation was an auxin-induced process, during which adventitious root primordium initiation (rpi) began at 14 days after cutting (DAC), root primordium (rp) was developed at 21 DAC, mature AR was observed at 28 DAC and finally outgrowth from the stem occurred at 35 DAC. Higher IAA levels and lower ABA and zeatin contents might facilitate AR formation and development. A time series transcriptome analysis identified 14,970 differentially expressed genes (DEGs) during AR formation, of which there were 7467 upregulated and 7503 downregulated genes. Of these, approximately 35 candidate DEGs involved in the auxin-induced pathway and AR formation were further identified, including 10 auxin respective genes (ARFs and SAURs), 13 transcription factors (LOB domain-containing protein (LBDs)), 6 auxin transporters (AUX22, LAX3/5 and PIN-like 6 (PIL6s)) and 6 rooting-associated genes (root meristem growth factor 9 (RGF9), lateral root primordium 1 (LRP1s), and dormancy-associated protein homologue 3 (DRMH3)). All these identified DEGs were highly upregulated in certain stages during AR formation, indicating their potential roles in blueberry AR formation. CONCLUSIONS: The transcriptome profiling results indicated candidate genes or major regulatory factors that influence adventitious root formation in blueberry and provided a comprehensive understanding of the rooting mechanism underlying the auxin-induced AR formation from blueberry green cuttings.
PMID: 32334538
BMC Plant Biol , IF:3.497 , 2020 Apr , V20 (1) : P180 doi: 10.1186/s12870-020-02394-4
Changes in carbohydrate metabolism and endogenous hormone regulation during bulblet initiation and development in Lycoris radiata.
Forestry and Pomology Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, 201403, China.; Forestry and Pomology Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, 201403, China. saasflower@163.com.
BACKGROUND: Lycoris species have great ornamental and medicinal values; however, their low regeneration efficiency seriously restricts their commercial production. Understanding the mechanism of bulblet propagation in this genus, which has remained underexplored to date, could provide a theoretical basis for improving the reproductive efficiency. Therefore, we studied the bulblet initiation and developmental processes in Lycoris radiata. RESULTS: We found that bulblets are formed on the junctions of the innermost layers of scales and the basal plate, and initially present as an axillary bud and gradually develop into a bulblet. We also determined the changes in carbohydrate and endogenous hormone contents during bulblet initiation and development, as well as the expression patterns of genes involved in carbohydrate metabolism and hormone biosynthesis and signaling through transcriptome analysis. Soluble sugars derived from starch degradation in the outer scales are transported to and promote bulblet initiation and development through starch synthesis in the inner scales. This process is mediated by several genes involved in carbohydrate metabolism, especially genes encoding ADP glucose pyrophosphorylase, a crucial starch synthesis enzyme. As for hormones, endogenous IAA, GA, and ABA content showed an increase and decrease during bulblet initiation and development, respectively, which were consistent with the expression patterns of genes involved in IAA, GA, and ABA synthesis and signal transduction. In addition, a decrease in ZR content may be down- and up-regulated by CK biosynthesis and degradation related genes, respectively, with increasing auxin content. Furthermore, expression levels of genes related to BR, JA, and SA biosynthesis were increased, while that of ethylene biosynthesis genes was decreased, which was also consistent with the expression patterns of their signal transduction genes. CONCLUSIONS: The present study provides insights into the effect of carbohydrate metabolism and endogenous hormone regulation on control of L. radiata bulblet initiation and development. Based on the results, we propose several suggestions to improve L. radiata propagation efficiency in production, which will provide directions for future research.
PMID: 32334530
BMC Plant Biol , IF:3.497 , 2020 Apr , V20 (1) : P162 doi: 10.1186/s12870-020-02373-9
LncRNA regulates tomato fruit cracking by coordinating gene expression via a hormone-redox-cell wall network.
College of Horticulture, Nanjing Agricultural University, Weigang NO 1, Nanjing, 210095, Xuanwu District, China.; Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in East China, Ministry of Agriculture, Nanjing, 210095, China.; Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Zhongguancun South St, Beijing, 10081, Haidian District, China.; Institute of Vegetables, Xinjiang Academy of Agricultural Sciences, Nanchang Road 403, Urumchi, 830091, Shayibake District, China.; College of Horticulture, Nanjing Agricultural University, Weigang NO 1, Nanjing, 210095, Xuanwu District, China. jfl@njau.edu.cn.; Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in East China, Ministry of Agriculture, Nanjing, 210095, China. jfl@njau.edu.cn.
BACKGROUND: Fruit cracking occurs easily under unsuitable environmental conditions and is one of the main types of damage that occurs in fruit production. It is widely accepted that plants have developed defence mechanisms and regulatory networks that respond to abiotic stress, which involves perceiving, integrating and responding to stress signals by modulating the expression of related genes. Fruit cracking is also a physiological disease caused by abiotic stress. It has been reported that a single or several genes may regulate fruit cracking. However, almost none of these reports have involved cracking regulatory networks. RESULTS: Here, RNA expression in 0 h, 8 h and 30 h saturated irrigation-treated fruits from two contrasting tomato genotypes, 'LA1698' (cracking-resistant, CR) and 'LA2683' (cracking-susceptible, CS), was analysed by mRNA and lncRNA sequencing. The GO pathways of the differentially expressed mRNAs were mainly enriched in the 'hormone metabolic process', 'cell wall organization', 'oxidoreductase activity' and 'catalytic activity' categories. According to the gene expression analysis, significantly differentially expressed genes included Solyc02g080530.3 (Peroxide, POD), Solyc01g008710.3 (Mannan endo-1,4-beta-mannosidase, MAN), Solyc08g077910.3 (Expanded, EXP), Solyc09g075330.3 (Pectinesterase, PE), Solyc07g055990.3 (Xyloglucan endotransglucosylase-hydrolase 7, XTH7), Solyc12g011030.2 (Xyloglucan endotransglucosylase-hydrolase 9, XTH9), Solyc10g080210.2 (Polygalacturonase-2, PG2), Solyc08g081010.2 (Gamma-glutamylcysteine synthetase, gamma-GCS), Solyc09g008720.2 (Ethylene receptor, ER), Solyc11g042560.2 (Ethylene-responsive transcription factor 4, ERF4) etc. In addition, the lncRNAs (XLOC_16662 and XLOC_033910, etc) regulated the expression of their neighbouring genes, and genes related to tomato cracking were selected to construct a lncRNA-mRNA network influencing tomato cracking. CONCLUSIONS: This study provides insight into the responsive network for water-induced cracking in tomato fruit. Specifically, lncRNAs regulate the hormone-redox-cell wall network, including plant hormone (auxin, ethylene) and ROS (H2O2) signal transduction and many cell wall-related mRNAs (EXP, PG, XTH), as well as some lncRNAs (XLOC_16662 and XLOC_033910, etc.).
PMID: 32293294
BMC Plant Biol , IF:3.497 , 2020 Apr , V20 (1) : P150 doi: 10.1186/s12870-020-02354-y
Indole-3-acetic acid improves drought tolerance of white clover via activating auxin, abscisic acid and jasmonic acid related genes and inhibiting senescence genes.
Department of Grassland Science, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, 611130, China.; College of Life science, Changchun Normal University, Changchun, 130032, China.; Department of Grassland Science, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, 611130, China. pengyanlee@163.com.
BACKGROUND: Auxin may have a positive effect on plants under drought stress. White clover is widely cultivated and often prone to water shortages. In the present study, we investigated the effects of exogenous indole - 3-acetic acid (IAA) on growth and physiological changes of white clover under drought stress condition. The contents of endogenous IAA and other hormones including ABA, CTK, JA, GA, IAA, and SA were assayed. Moreover, expressions of auxin-responsive genes, drought-responsive genes and leaf senescence-associated genes were detected in response to exogenous IAA. RESULTS: Compared to control, drought stress alone significantly diminished stem dry weigh, relative water content (RWC) and total chlorophyll content (Chl). Exogenous IAA treatment significantly increased RWC and Chl, whereas L-AOPP treatment drastically decreased stem dry weight, RWC and Chl under drought stress condition. Additionally, exogenous IAA treatment significantly increased ABA content and JA content, up-regulated expression of auxin responsive genes (GH3.1, GH3.9, IAA8), drought stress responsive genes (bZIP11, DREB2, MYB14, MYB48, WRKY2, WRKY56, WRKY108715 and RD22), and down-regulated expressions of auxin-responding genes (GH3.3, GH3.6, IAA27) and leaf senescence genes (SAG101 and SAG102) in the presence of PEG. Contrarily, L-AOPP treatment significantly reduced contents of ABA, GA3 and JA, down-regulated expressions of GH3.1, GH3.9, IAA8, bZIP11, DREB2, MYB14, MYB48, WRKY2, WRKY56, WRKY108715, ERD and RD22, and up-regulated SAG101 and SAG102. CONCLUSIONS: Exogenous IAA improved drought tolerance of white clover possibly due to endogenous plant hormone concentration changes and modulation of genes involving in drought stress response and leaf senescence. These results provided useful information to understand mechanisms of IAA improved drought tolerance in white clover.
PMID: 32268884
Dev Dyn , IF:3.275 , 2020 Apr doi: 10.1002/dvdy.181
GAL4/GFP enhancer-trap lines for identification and manipulation of cells and tissues in developing Arabidopsis leaves.
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
BACKGROUND: Understanding developmental processes requires the unambiguous identification of cells and tissues, and the selective manipulation of the properties of those cells and tissues. Both requirements can most efficiently be satisfied through the use of GAL4/GFP enhancer-trap lines. No such lines, however, have been characterized for the study of early leaf development in the Columbia-0 reference genotype of Arabidopsis. RESULTS: Here we address this limitation by identifying and characterizing a set of GAL4/GFP enhancer-trap lines in the Columbia-0 background for the specific labeling of cells and tissues during early leaf development, and for the targeted expression of genes of interest in those cells and tissues. CONCLUSIONS: By using one line in our set to address outstanding questions in leaf vein patterning, we show that these lines can be used to address key questions in plant developmental biology.
PMID: 32319191
Dev Dyn , IF:3.275 , 2020 Apr , V249 (4) : P483-495 doi: 10.1002/dvdy.139
Regulation of auxin transcriptional responses.
Department of Biology, Washington University in St. Louis, St. Louis, Missouri.; Center for Science and Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, Missouri.; Center for Engineering MechanoBiology, Washington University in St. Louis, St. Louis, Missouri.
The plant hormone auxin acts as a signaling molecule to regulate a vast number of developmental responses throughout all stages of plant growth. Tight control and coordination of auxin signaling is required for the generation of specific auxin-response outputs. The nuclear auxin signaling pathway controls auxin-responsive gene transcription through the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX pathway. Recent work has uncovered important details into how regulation of auxin signaling components can generate unique and specific responses to determine auxin outputs. In this review, we discuss what is known about the core auxin signaling components and explore mechanisms important for regulating auxin response specificity.
PMID: 31774605
Am J Bot , IF:3.038 , 2020 Apr , V107 (4) : P577-586 doi: 10.1002/ajb2.1463
The role of auxin in developmentally regulated programmed cell death in lace plant.
Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, NS, B3H 4R2, Canada.
PREMISE: Lace plant (Aponogeton madagascariensis) leaves are remodeled via developmental programmed cell death (PCD) to produce perforations located equidistantly between longitudinal and transverse veins. Auxin has been implicated in other developmental PCD processes in plants; however, the role of auxin in perforation formation in lace plant is unknown. Here the role of auxin in developmental PCD in lace plant was studied using two auxin inhibitors N-1-naphthylphthalamic acid (NPA), an auxin transport inhibitor, and auxinole, a potent auxin antagonist. METHODS: Sterile cultures of lace plants were propagated and treated with NPA or auxinole. Leaf length, leaf width, and number of perforations were then analyzed. Vein patterning and perforation area were further examined in NPA-treated plants. Downstream PCD transduction events were investigated via spectrophotometric assays, histochemical staining, and immuno-probing. RESULTS: Lace plants treated with NPA or auxinole produced leaves with fewer perforations compared to their respective controls. Although NPA treatment was insufficient to completely alter vein patterning, NPA-treated leaves did have significantly more atypical areoles compared to control leaves. Events involved in perforation formation in lace plant leaves were altered following treatment with NPA, including anthocyanin production, reactive oxygen species (ROS) accumulation, and the release of mitochondrial cytochrome c. CONCLUSIONS: Our results indicated that inhibition of auxin signaling disrupts several downstream features of the lace plant PCD signaling cascade and results in fewer or no perforations. Therefore, we concluded that auxin signaling is important for developmentally regulated PCD in lace plant leaves.
PMID: 32319093
ACS Omega , IF:2.87 , 2020 Apr , V5 (16) : P9585-9597 doi: 10.1021/acsomega.0c00961
Fluoresceinated Aminohexanol Tethered Inositol Hexakisphosphate: Studies on Arabidopsis thaliana and Drosophila melanogaster and Docking with 2P1M Receptor.
TERI School of Advanced Studies, Plot No. 10, Vasant Kunj Institutional Area, Vasant Kunj, Institutional Area, New Delhi 110070, India.; Regional Centre for Biotechnology (RCB), NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, 121001 Haryana, India.; Amity University, Noida, 201313 Uttar Pradesh, India.; Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, 121001 Haryana, India.; Teri Deakin Nano Biotechnology Centre (TDNBC), Teri Gram, Gwal Pahari, Gurgaon- Faridabad Expressway, Gurugram, 122002 Haryana, India.
Inositol hexakisphosphate (InsP6; phytic acid) is considered as the second messenger and plays a very important role in plants, animals, and human beings. It is the principal storage form of phosphorus in many plant tissues, especially in dry fruits, bran, and seeds. The resulting anion is a colorless species that plays a critical role in nutrition and is believed to cure many diseases. A fluoresceinated aminohexanol tethered inositol hexakisphosphate (III) had been synthesized earlier involving many complicated steps. We describe here a simple two-step synthesis of (III) and its characterization using different techniques such as matrix-assisted laser desorption ionization mass spectrometry, tandem mass spectrometry, and Fourier transform infrared, ultraviolet-visible, ultraviolet-fluorescence, (1)H nuclear magnetic resonance (NMR), and two-dimensional NMR spectroscopies. The effect of (III) has been investigated in the model systems, Arabidopsis thaliana and Drosophila melanogaster. Using Schrodinger software, computational studies on the binding of (III) with the protein 2P1M (Auxin-receptor TIR1-adaptor ASK1 complex) has revealed strong binding propensity with this compound. These studies on the fluoresceinated tethered phytic acid could have far reaching implications on its efficacy for human health and treatment of diseases (cancer/tumor and glioblastoma) and for understanding phosphorous recycling in the environment, especially for plant systems.
PMID: 32363311
Plants (Basel) , IF:2.762 , 2020 Apr , V9 (4) doi: 10.3390/plants9040524
In Vitro Propagation of Gastrochilus matsuran (Makino) Schltr., an Endangered Epiphytic Orchid.
Babo Orchid Farm, Namyangju-si, Gyeonggi-do 472-831, Korea.; Department of Bioresources and Food Science, Institute of Natural Science and Agriculture, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 05029, Korea.
Gastrochilus matsuran (Makino) Schltr. (Orchidaceae) populations are declining quickly because of overexploitation, climatic changes, and deforestation; therefore, mass-production protocols are required for this orchid. Natural propagation of this species is often hampered by meager seed germination and slow growth. Thus, our aim was to establish an effective protocol for the in vitro propagation of G. matsuran and reduce the risk of its extinction. We investigated the impacts of culture media, coconut water (CW), and plant hormones (gibberellic acid (GA3), indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), alpha-naphthaleneacetic acid (NAA), and thidiazuron (TDZ)) on asymbiotic germination, multiplication and conversion of protocorms, and plantlet development. Maximal seed germination (93.3%) was achieved on (1/2) MS medium without vitamins plus 5% CW, 1 microM NAA, and 1.5 microM GA3. Secondary protocorm formation was best achieved on (1/2) MS medium without vitamins plus 2 microM TDZ. The conversion of protocorms into seedlings was maximized by supplementation with 2 microM IBA or 1 microM NAA. Acclimatized plantlets that exhibited exuberant growth on sphagnum moss were reintroduced to tree trunks in a natural habitat, with a 67% survival rate. This in vitro propagation procedure would be helpful for the mass production and conservation of this rare epiphytic orchid.
PMID: 32325758
Plants (Basel) , IF:2.762 , 2020 Apr , V9 (4) doi: 10.3390/plants9040498
Micropropagation and Production of Somatic Seeds for Short-Term Storage of the Endangered Species Eryngium alpinum L.
Department of Pharmaceutical Botany and Plant Biotechnology, University of Medical Sciences in Poznan, 14 Sw. Marii Magdaleny St., 61-861 Poznan, Poland.; Laboratory of Molecular Biology and Cytometry, Department of Agricultural Biotechnology, UTP University of Science and Technology, Prof. S. Kaliskiego Ave. 7, 85-789, Bydgoszcz, Poland.
Eryngium alpinum L. is a high-value herb and a source of important compounds that include phenolics, triterpenoid saponins, and essential oils. The present report indicates successful micropropagation of this species. In our study, medium supplemented with BAP 2.0 mg/L, IAA 1.0 mg/L, and GA3 1.0 mg/L was found to be the most suitable for long-term culture and for effective proliferation, irrespective of the passage number. Roots induction, without basal callus formation, was observed when individual microshoots were placed on Murashige & Skoog medium augmented with auxin, and formation was the most advantageous in the presence of NAA alone or when combined with IAA or IBA. The encapsulated propagules were tested for their capability to endure different storage periods under low temperature. Therefore, we developed an efficient method for synseeds production by encapsulation of axillary buds in the sodium alginate matrix, storage for 2, 4, and 6 months, as well as the regeneration process. The maximum regeneration rate of 74% +/- 2.72% was observed for axillary buds encapsulated in 4% sodium-alginate complexed with 300 mM calcium chloride after 2 months of storage at low temperature. This is the first report on E. alpinum micropropagation and somatic seeds production.
PMID: 32295044
Rapid Commun Mass Spectrom , IF:2.2 , 2020 Apr , V34 (7) : Pe8625 doi: 10.1002/rcm.8625
Practical optimization of liquid chromatography/mass spectrometry conditions and pretreatment methods toward the sensitive quantification of auxin in plants.
Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan.
RATIONALE: The plant hormone auxin, indole-3-acetic acid, regulates many aspects of plant growth and development. Auxin quantification should offer broad insights into its mechanistic action in plants. However, limited auxin content in plant tissues hampers the establishment of quantification methods without the highest graded instruments or deeply specialized experimental techniques. METHODS: In this study, we detailed optimized conditions for high-performance liquid chromatography coupled with triple-quadrupole mass spectrometry (LC/MS). We compared LC/MS conditions, such as columns, mobile phases, parameters of acquisition methods (selective or multiple ion monitoring), dwell times (DTs), and channel numbers, using differentially mixed authentic auxin and its related compounds. We further investigated pretreatment methods through the optimization of auxin recovery and irrelative compound removal from plant tissues prior to the LC/MS analysis. RESULTS: Our LC/MS analysis demonstrated the particular importance of the column, DTs, and channel numbers on detection sensitivity. Our comparative analysis developed optimal pretreatment methods, including the pulverization of plants, concentration of extract through centrifugal evaporation, and removal of irrelative metabolites using liquid-liquid extraction and a spin filter. We injected plant samples into our LC/MS system, quantified auxin and eight related compounds in a single measurement, and determined the auxin increase in an auxin over-producing mutant. CONCLUSIONS: Our practical optimization of LC/MS conditions and pretreatment methods provides detailed experimental processes toward the sensitive quantification of auxin from 10 mg of plant tissue. These processes have not always been clearly documented; therefore, our protocol could broadly contribute to technical advances in plant growth and development research.
PMID: 31658390
Plant Biol (Stuttg) , IF:2.167 , 2020 Apr doi: 10.1111/plb.13124
Plant growth-promoting endophytic bacteria augment growth and salinity tolerance in rice plants.
School of Applied Biosciences, Kyungpook National University, Daegu, Republic of Korea.; Natural and Medical Sciences Research Center, University of Nizwa, Nizwa, Oman.
Salt stress negatively affects growth and development of plants. However, it is hypothesized that plant growth-promoting endophytic bacteria can greatly alleviate the adverse effects of salinity and can promote growth and development of plants. In the present research, we aimed to isolate endophytic bacteria from halotolerant plants and evaluate their capacity for promoting crop plant growth. The bacterial endophytes were isolated from selected plants inhabiting sand dunes at Pohang beach, screened for plant growth-promoting traits and applied to rice seedlings under salt stress (NaCl; 150 mm). Out of 59 endophytic bacterial isolates, only six isolates, i.e. Curtobacterium oceanosedimentum SAK1, Curtobacterium luteum SAK2, Enterobacter ludwigii SAK5, Bacillus cereus SA1, Micrococcus yunnanensis SA2, Enterobacter tabaci SA3, resulted in a significant increase in the growth of Waito-C rice. The cultural filtrates of bacterial endophytes were tested for phytohormones, including indole-3-acetic acid, gibberellins and organic acids. Inoculation of the selected strains considerably reduced the amount of endogenous ABA in rice plants under NaCl stress, however, they increased GSH and sugar content. Similarly, these strains augmented the expression of flavin monooxygenase (OsYUCCA1) and auxin efflux carrier (OsPIN1) genes under salt stress. In conclusion, the pragmatic application of the above selected bacterial strains alleviated the adverse effects of NaCl stress and enhanced rice growth attributes by producing various phytohormones.
PMID: 32329163
Physiol Mol Biol Plants , IF:2.005 , 2020 Apr , V26 (4) : P733-745 doi: 10.1007/s12298-019-00752-7
Analysis of the impact of indole-3-acetic acid (IAA) on gene expression during leaf senescence in Arabidopsis thaliana.
1Division of Botany, Biology Department, Faculty of Science, Istanbul University, Istanbul, Turkey.grid.9601.e0000 0001 2166 6619; 2School of Life Sciences, University of Warwick, Coventry, CV4 7AL UK.grid.7372.10000 0000 8809 1613
Leaf senescence is an important developmental process for the plant life cycle. It is controlled by endogenous and environmental factors and can be positively or negatively affected by plant growth regulators. It is characterised by major and significant changes in the patterns of gene expression. Auxin, especially indole-3-acetic acid (IAA), is a plant growth hormone that affects plant growth and development. The effect of IAA on leaf senescence is still unclear. In this study, we performed microarray analysis to investigate the role of IAA on gene expression during senescence in Arabidopsis thaliana. We sprayed IAA on plants at 3 different time points (27, 31 or 35 days after sowing). Following spraying, PSII activity of the eighth leaf was evaluated daily by measurement of chlorophyll fluorescence parameters. Our results show that PSII activity decreased following IAA application and the IAA treatment triggered different gene expression responses in leaves of different ages.
PMID: 32255936
Curr Microbiol , IF:1.746 , 2020 Apr , V77 (4) : P564-577 doi: 10.1007/s00284-020-01917-4
The Effect of Auxin and Auxin-Producing Bacteria on the Growth, Essential Oil Yield, and Composition in Medicinal and Aromatic Plants.
Faculty of Agriculture, Department of Field Crops, Canakkale Onsekiz Mart University, Canakkale, Turkey. rcakmakci@comu.edu.tr.; Faculty of Agriculture, Department of Field Crops, Ataturk University, Erzurum, Turkey.; Faculty of Agriculture, Department of Field Crops, Canakkale Onsekiz Mart University, Canakkale, Turkey.
Aromatic plants had been used since ancient times for their preservative and medicinal properties, and to impart aroma and flavor to food. Also their secondary metabolites are economically important as drugs, flavor and fragrances, pharmaceuticals, agrochemicals, dye, and pigments, pesticides, cosmetics, food additives, other industrially biochemical, and also play a major role in the adaptation of plants to their environment. Indole acetic acid-producing rhizobacteria inoculations increase in stomatal density and level of secondary metabolite and have a synergistic effect on monoterpene biosynthesis. Bacterial inoculation significantly affected and increased the chemical composition of essential oil, citronellol, and geraniol content in rose-scented geranium; essential oil composition and total phenolic content in marigold; density, number, and size of glandular trichomes in sweet wormwood and peppermint essential oil components such as geranyl acetate, limonene, and beta-pinene in coriander; oil yield and content in calendula; yield of the herb in hyssop; oxygenated compounds, essential oil content and yield, anethol and changing the chemical composition in fennel; growth, number of glandular trichomes and essential oil yield, root branching and length, and total amount of essential oil, production of monoterpenes such as pulegone, menthol, menthone, menthofuran, and terpineol content, biosynthesis of secondary metabolites in peppermint; growth and essential oil yield in marjoram; glandular hair abundance, essential oil yield, and monoterpene biosynthesis in basil; phellandrene, limonene, borneol, and campor in rosemary; carvacrol, thymol, linalool, and borneol in oregano; and alpha-thujene, alpha-pinene, alpha-terpinene, p-simen, beta-pinene, and gamma-terpinene contents and essential oil yield in summer savory. Inoculation with IAA-producing bacteria medicinal roots increased the valerenic acid in valerian, essential oil and quality in vetiver, curcumin content in turmeric alkaloid and ginsenoside content in ginseng, and inulin content in Jerusalem artichoke.
PMID: 32080752
Plant Direct , IF:1.725 , 2020 Apr , V4 (4) : Pe00215 doi: 10.1002/pld3.215
A gravitropic stimulus alters the distribution of EHB1, a negative effector of root gravitropism in Arabidopsis.
Fachbereich Biologie Philipps-Universitat Marburg Marburg Germany.; Institut fur Biologie Universitat Siegen Siegen Germany.
In Arabidopsis gravitropism is affected by two antagonistically interacting proteins, AGD12 (ADP-RIBOSYLATION FACTOR GTPase-ACTIVATING PROTEIN) and EHB1 (ENHANCED BENDING 1). While AGD12 enhances gravitropic bending, EHB1 functions as a negative element. To further characterize their cellular function, we analyzed the location of AGD12-GFP and EHB1-GFP fusion proteins in the root apex by confocal laser-scanning microscopy after gravitropic stimulation. For this purpose, a novel method of microscopic visualization was developed with the objective and root axes aligned allowing an improved and comparable discernment of the fluorescence gradient across the columella. In vertical roots, both proteins were localized symmetrically and occurred preferentially in the outer layers of the columella. After reorienting roots horizontally, EHB1-GFP accumulated in the upper cell layers of the columella, that is, opposite to the gravity vector. The gravity-induced EHB1-GFP asymmetry disappeared after reorienting the roots back into the vertical position. No such asymmetry occurred with AGD12-GFP. Our findings reveal that after a gravitropic stimulus the cellular ratio between EHB1 and AGD12 is affected differently in the upper and lower part of the root. Its impact as a significant signaling event that ultimately affects the redirection of the lateral auxin flux toward the lower site of the root is discussed.
PMID: 32318652
Plant Direct , IF:1.725 , 2020 Apr , V4 (4) : Pe00212 doi: 10.1002/pld3.212
Exogenous sodium diethyldithiocarbamate, a Jasmonic acid biosynthesis inhibitor, induced resistance to powdery mildew in wheat.
Key Laboratory of Crop Heterosis and Utilization (MOE) and State Key Laboratory for Agrobiotechnology Beijing Key Laboratory of Crop Genetic Improvement China Agricultural University Beijing China.; Institute of Evolution University of Haifa, Mt. Carmel Haifa Israel.
Jasmonic acid (JA) is an important plant hormone associated with plant-pathogen defense. To study the role of JA in plant-fungal interactions, we applied a JA biosynthesis inhibitor, sodium diethyldithiocarbamate (DIECA), on wheat leaves. Our results showed that application of 10 mM DIECA 0-2 days before inoculation effectively induced resistance to powdery mildew (Bgt) in wheat. Transcriptome analysis identified 364 up-regulated and 68 down-regulated differentially expressed genes (DEGs) in DIECA-treated leaves compared with water-treated leaves. Gene ontology (GO) enrichment analysis of the DEGs revealed important GO terms and pathways, in particular, response to growth hormones, activity of glutathione metabolism (e.g., glutathione transferase activity), oxalate oxidase, and chitinase activity. Gene annotaion revealed that some pathogenesis-related (PR) genes, such as PR1.1, PR1, PR10, PR4a, Chitinase 8, beta-1,3-glucanase, RPM1, RGA2, and HSP70, were induced by DIECA treatment. DIECA reduced JA and auxin (IAA) levels, while increased brassinosteroid, glutathione, and ROS lesions in wheat leaves, which corroborated with the transcriptional changes. Our results suggest that DIECA can be applied to increase plant immunity and reduce the severity of Bgt disease in wheat fields.
PMID: 32285024
Plant Signal Behav , IF:1.671 , 2020 Apr , V15 (4) : P1744347 doi: 10.1080/15592324.2020.1744347
Expression of rice siR109944 in Arabidopsis affects plant immunity to multiple fungal pathogens.
College of Plant Protection, Nanjing Agricultural University, Nanjing, China.; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, China.; Department of Microbiology & Plant Pathology, University of California, Riverside, CA, USA.
Plant small RNA (sRNA)-mediated gene expression has a conserved role in regulating plant growth, development, and immunity. Heterologous expression of sRNA contributes to determining whether the function of sRNA is conservative or independent. We recently characterized the Tourist-miniature inverted-repeat transposable element (MITE)-derived siR109944 had a conserved function that enhanced susceptibility to Rhizoctonia solani infection by affecting auxin homeostasis in rice and Arabidopsis. To ascertain whether the function of rice siR109944 has a broad-spectrum immunity in Arabidopsis, we infected Arabidopsis with a variety of fungal pathogens. Overexpression of siR109944 in Arabidopsis increased susceptibility to Botrytis cinerea, Sclerotinia sclerotium, and Verticillium dahliae infection. Further studies found that Arabidopsis auxin-related miRNAs were suppressed in siR109944 OE. Our results demonstrated that overexpression of rice siR109944 in Arabidopsis affected immune responses to multiple pathogens by inhibiting auxin-related miRNA expression in planta.
PMID: 32202463
Plant Signal Behav , IF:1.671 , 2020 Apr , V15 (4) : P1739842 doi: 10.1080/15592324.2020.1739842
Synchronization of photoperiod and temperature signals during plant thermomorphogenesis.
Department of Chemistry, Seoul National University, Seoul, Korea.; Plant Genomics and Breeding Institute, Seoul National University, Seoul, Korea.
It is well-known that even small changes in ambient temperatures by a few degrees profoundly affect plant growth and morphology. This architectural property is intimately associated with global warming. In particular, under warm temperature conditions, plants exhibit distinct morphological changes, such as elongation of hypocotyls and leaf petioles, formation of small, thin leaves, and leaf hyponasty that describes an upward bending of leaf petioles. These thermoresponsive morphological adjustments are termed thermomorphogenesis. Under warm temperature conditions, the PHYTOCHROME INTERACTING FACTOR 4 (PIF4) transcription factor is thermoactivated and stimulates the transcription of the YUCCA8 gene encoding an auxin biosynthetic enzyme, promoting hypocotyl elongation. Notably, these thermomorphogenic growth is influenced by daylength or photoperiod, displaying relatively high and low thermomorphogenic hypocotyl growth during the nighttime under short days and long days, respectively. We have recently reported that the photoperiod signaling regulator GIGANTEA (GI) thermostabilizes the REPRESSOR OF ga1-3 transcription factor, which is known to attenuate the PIF4-mediated thermomorphogenesis. We also found that the N-terminal domain of GI interacts with PIF4, possibly destabilizing the PIF4 proteins. We propose that the GI-mediated shaping of photoperiodic rhythms of hypocotyl thermomorphogenesis helps plant adapt to fluctuations in daylength and temperature environments occurring during seasonal transitions.
PMID: 32163001
Genes Genomics , IF:1.188 , 2020 Apr , V42 (4) : P383-392 doi: 10.1007/s13258-019-00912-9
Proteome analysis provides new insight into major proteins involved in gibberellin-induced fruit setting in triploid loquat (Eriobotrya japonica).
Forestry and Pomology Research Institute, Shanghai Key Lab of Protected Horticultural Technology, Shanghai Academy of Agricultural Sciences, Shanghai, 201403, China.; Forestry and Pomology Research Institute, Shanghai Key Lab of Protected Horticultural Technology, Shanghai Academy of Agricultural Sciences, Shanghai, 201403, China. loquat_zhang@126.com.
BACKGROUND: Parthenocarpy can be induced by gibberellin (GA) treatment in plants. The fruits of the loquat exhibit many seeds. GA treatment can induce the development of seedless fruit and increase fruit quality during production. However, the molecular mechanism of fruit setting under GA treatment is still unclear. OBJECTIVE: Our aim was to explore GA-induced parthenocarpy in triploid loquat by proteome analysis to identify the differentially expressed proteins. METHODS: A proteome analysis was performed using TMT protein labeling and LC-MS/MS in triploid loquat. RESULTS: A total of 7290 protein groups were identified in the two stages of fruit setting. The quantitative results showed that 923 differentially expressed proteins (DEPs) were isolated, which were enriched in five pathways: ribosome, citrate cycle (TCA cycle), pentose phosphate, carbon metabolism, and carbon fixation. Twenty-four DEPs were annotated as putative key regulatory proteins involved in fruit setting, which were related to the auxin response, gibberellin metabolism, ethylene synthesis, and cell division. In addition, thirty-five DEPs were involved in the formation of the cell wall, which might be downstream proteins involved in cell proliferation during fruit setting. CONCLUSION: Our report reveals new insight into the protein dynamics of loquat fruit setting induced by GA treatment via the analysis of proteome profiles and provides a reference for other Rosaceae species.
PMID: 31902111