scholarly journals Natural variation identifies genes affecting drought-induced abscisic acid accumulation in Arabidopsis thaliana

2017 ◽  
Vol 114 (43) ◽  
pp. 11536-11541 ◽  
Author(s):  
Rajesh Kalladan ◽  
Jesse R. Lasky ◽  
Trent Z. Chang ◽  
Sandeep Sharma ◽  
Thomas E. Juenger ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Abscisic Acid ◽  
Water Potential ◽  
Natural Variation ◽  
Lipid Binding ◽  
Reverse Genetic ◽  
Loss Of Function ◽  
Start Domain ◽  
Domain Protein ◽  
Low Water Potential

Accumulation of the stress hormone abscisic acid (ABA) in response to drought and low water-potential controls many downstream acclimation mechanisms. However, mechanisms controlling ABA accumulation itself are less known. There was a 10-fold range of variation in ABA levels among nearly 300 Arabidopsis thaliana accessions exposed to the same low water-potential severity. Genome-wide association analysis (GWAS) identified genomic regions containing clusters of ABA-associated SNPs. Candidate genes within these regions included few genes with known stress or ABA-related function. The GWAS data were used to guide reverse genetic analysis, which found effectors of ABA accumulation. These included plasma-membrane–localized signaling proteins such as receptor-like kinases, aspartic protease, a putative lipid-binding START domain protein, and other membrane proteins of unknown function as well as a RING U-box protein and possible effect of tonoplast transport on ABA accumulation. Putative loss-of-function polymorphisms within the START domain protein were associated with climate factors at accession sites of origin, indicating its potential involvement in drought adaptation. Overall, using ABA accumulation as a basis for a combined GWAS–reverse genetic strategy revealed the broad natural variation in low-water-potential–induced ABA accumulation and was successful in identifying genes that affect ABA levels and may act in upstream drought-related sensing and signaling mechanisms. ABA effector loci were identified even when each one was of incremental effect, consistent with control of ABA accumulation being distributed among the many branches of ABA metabolism or mediated by genes with partially redundant function.

scholarly journals Brassinosteroids repress the seed maturation program during the seed-to-seedling transition

2021 ◽  
Author(s):  
Jiuxiao Ruan ◽  
Huhui Chen ◽  
Tao Zhu ◽  
Yaoguang Yu ◽  
Yawen Lei ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Transcription Factor ◽  
Abscisic Acid ◽  
Plant Hormone ◽  
Flowering Plants ◽  
Seed Maturation ◽  
Domain Protein ◽  
Abscisic Acid Insensitive3 ◽  
Underlying Mechanisms ◽  
Embryonic Structure

Abstract In flowering plants, repression of the seed maturation program is essential for the transition from the seed to the vegetative phase, but the underlying mechanisms remain poorly understood. The B3-domain protein VIVIPAROUS1/ABSCISIC ACID-INSENSITIVE3-LIKE 1 (VAL1) is involved in repressing the seed maturation program. Here we uncovered a molecular network triggered by the plant hormone brassinosteroid (BR) that inhibits the seed maturation program during the seed-to-seedling transition in Arabidopsis (Arabidopsis thaliana). val1-2 mutant seedlings treated with a BR biosynthesis inhibitor form embryonic structures, whereas BR signaling gain-of-function mutations rescue the embryonic structure trait. Furthermore, the BR-activated transcription factors BRI1-EMS-SUPPRESSOR 1 and BRASSINAZOLE-RESISTANT 1 bind directly to the promoter of AGAMOUS-LIKE15 (AGL15), which encodes a transcription factor involved in activating the seed maturation program, and suppress its expression. Genetic analysis indicated that BR signaling is epistatic to AGL15 and represses the seed maturation program by downregulating AGL15. Finally, we showed that the BR-mediated pathway functions synergistically with the VAL1/2-mediated pathway to ensure the full repression of the seed maturation program. Together, our work uncovered a mechanism underlying the suppression of the seed maturation program, shedding light on how BR promotes seedling growth.

scholarly journals Abscisic acid regulates secondary cell-wall formation and lignin deposition in Arabidopsis thaliana through phosphorylation of NST1

2021 ◽  
Vol 118 (5) ◽  
pp. e2010911118
Author(s):  
Chang Liu ◽  
Hasi Yu ◽  
Xiaolan Rao ◽  
Laigeng Li ◽  
Richard A. Dixon
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Abscisic Acid ◽  
Transcriptional Activation ◽  
Secondary Cell Wall ◽  
Wall Thickening ◽  
Gene Promoters ◽  
Loss Of Function ◽  
Tolerance Strategy ◽  
Pathway Gene

Plant secondary cell-wall (SCW) deposition and lignification are affected by both seasonal factors and abiotic stress, and these responses may involve the hormone abscisic acid (ABA). However, the mechanisms involved are not clear. Here we show that mutations that limit ABA synthesis or signaling reduce the extent of SCW thickness and lignification in Arabidopsis thaliana through the core ABA-signaling pathway involving SnRK2 kinases. SnRK2.2. 3 and 6 physically interact with the SCW regulator NAC SECONDARY WALL THICKENING PROMOTING FACTOR 1 (NST1), a NAC family transcription factor that orchestrates the transcriptional activation of a suite of downstream SCW biosynthesis genes, some of which are involved in the biosynthesis of cellulose and lignin. This interaction leads to phosphorylation of NST1 at Ser316, a residue that is highly conserved among NST1 proteins from dicots, but not monocots, and is required for transcriptional activation of downstream SCW-related gene promoters. Loss of function of NST1 in the snd1 mutant background results in lack of SCWs in the interfascicular fiber region of the stem, and the Ser316Ala mutant of NST1 fails to complement this phenotype and ABA-induced lignin pathway gene expression. The discovery of NST1 as a key substrate for phosphorylation by SnRK2 suggests that the ABA-mediated core-signaling cascade provided land plants with a hormone-modulated, competitive desiccation-tolerance strategy allowing them to differentiate water-conducting and supporting tissues built of cells with thicker cell walls.

scholarly journals Plant trichomes and a single gene GLABRA1 contribute to insect community composition on field-grown Arabidopsis thaliana

2018 ◽  
Author(s):  
Yasuhiro Sato ◽  
Rie Shimizu-Inatsugi ◽  
Misako Yamazaki ◽  
Kentaro K. Shimizu ◽  
Atsushi J. Nagano
Keyword(s):  
Arabidopsis Thaliana ◽  
Community Composition ◽  
Natural Variation ◽  
Single Gene ◽  
Insect Community ◽  
Loss Of Function ◽  
Insect Communities ◽  
As Species ◽  
Distant Field ◽  
Diverse Plant

AbstractBackground: Genetic variation in plants alters insect abundance and community structure in the field; however, little is known about the importance of a single gene among diverse plant genotypes. In this context, Arabidopsis trichomes provide an excellent system to discern the roles of natural variation and a key gene, GLABRA1, in shaping insect communities. In this study, we transplanted two independent glabrous mutants (gl1-1 and gl1-2) and 17 natural accessions of Arabidopsis thaliana to two localities in Switzerland and Japan.Results: Fifteen insect species inhabited plant accessions, with 10–30% broad-sense heritability of community indices being detected, such as species richness and diversity. The total abundance of leaf-chewing herbivores was negatively correlated with trichome density at both the field sites, while glucosinolates had variable effects on leaf chewers between the two sites. Interestingly, there was a parallel tendency for the abundance of leaf chewers to be higher on gl1-1 and gl1-2 than for their different parental accessions, Ler-1 and Col-0, respectively. Furthermore, the loss of function in the GLABRA1 gene significantly decreased the resistance of plants to the two predominant chewers, flea beetles and turnip sawflies.Conclusions: Overall, our results indicate that insect community composition on A. thaliana is heritable across two distant field sites, with GLABRA1 playing a key role in altering the abundance of leaf-chewing herbivores. Given that such a trichome variation is widely observed in Brassicaceae plants, the present study exemplifies the community-wide impact of a single plant gene on crucifer-feeding insects in the field.

scholarly journals Arabidopsis thaliana SEED DORMANCY 4-LIKE regulates dormancy and germination by mediating the gibberellin pathway

2019 ◽  
Vol 71 (3) ◽  
pp. 919-933 ◽  
Author(s):  
Hong Cao ◽  
Yi Han ◽  
Jingyi Li ◽  
Meng Ding ◽  
Yu Li ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Abscisic Acid ◽  
Seed Dormancy ◽  
Molecular Mechanisms ◽  
Loss Of Function ◽  
Cell Wall Remodeling ◽  
Biochemical Function ◽  
Ga Biosynthesis ◽  
Seed Dormancy And Germination

Abstract The molecular mechanisms underlying seed dormancy and germination are not fully understood. Here, we show that Arabidopsis thaliana SEED DORMANCY 4-LIKE (AtSdr4L) is a novel specific regulator of dormancy and germination. AtSdr4L encodes a protein with an unknown biochemical function that is localized in the nucleus and is expressed specifically in seeds. Loss of function of AtSdr4L results in increased seed dormancy. The germination of freshly harvested seeds of the Atsdr4l mutant is insensitive to gibberellin (GA). After-ripened mutant seeds are hypersensitive to the GA biosynthesis-inhibitor paclobutrazol but show unaltered sensitivity to abscisic acid. Several GA biosynthesis genes and GA-regulated cell wall remodeling genes are down-regulated in the mutant in both dormant and after-ripened seeds. These results suggest that the Atsdr4l mutation causes both decreased GA biosynthesis and reduced responses. In addition, a genetic analysis indicated that AtSdr4L is epistatic to DELAY OF GERMINATION1 (DOG1) for dormancy and acts upstream of RGA-LIKE 2 (RGL2) in the GA pathway. We propose that AtSdr4L regulates seed dormancy and germination by mediating both the DOG1 and GA pathways.

scholarly journals Natural Genetic Variation Shapes Root System Responses to Phytohormones in Arabidopsis

2017 ◽  
Author(s):  
Daniela Ristova ◽  
Kristina Metesch ◽  
Wolfgang Busch
Keyword(s):  
Arabidopsis Thaliana ◽  
Genetic Variation ◽  
Abscisic Acid ◽  
Root System ◽  
Plant Hormones ◽  
Natural Variation ◽  
Reference Strain ◽  
Root Traits ◽  
Model Species ◽  
Hormone Responses

ABSTRACTPlants adjust their architecture by modulating organ growth. This ability is largely dependent on phytohormones. While many genes involved in phytohormone pathways have been identified, it remains unclear to which extent and how these pathways are modulated in non-reference strains and whether this is relevant for local adaptation. Here we assess variation of root traits in response to perturbations of the auxin, cytokinin, and abscisic acid pathways in 192 Arabidopsis accessions. We identify common response patterns, uncover the extent of their modulation by specific genotypes, and find that the Col-0 reference accession is not a good representative of the species in this regard. We conduct GWAS and identify 114 significant associations, most of them relating to ABA treatment. The numerous ABA candidate genes are not enriched for known ABA associated genes indicating that we largely uncovered unknown players. We then study two associated regions in detail and identify the CRF3 gene as a modulator of multiple hormone pathways. Finally, we show that natural variation in root traits is significantly associated with climate parameters relevant for local adaption in Arabidopsis thaliana and that, in particular, ABA regulated lateral root traits are likely to be relevant for adaptation to soil moisture.Author SummaryThe root system is a key component for plant survival and productivity. Apart from anchoring the plant, its architecture determines which parts of the soil are foraged for water and nutrients, and it serves as an interface for interaction with microbes and other soil organisms. Plant hormones play crucial roles in the development of root system architecture and its plasticity. However, while there is substantial natural variation of root architectures, it is not clear to which extent genetic variation in hormone related pathways contribute. Using the model species Arabidopsis thaliana we quantitatively explore the breadth of natural variation in plant hormone responses to three major plant hormones: auxin, cytokinin, and abscisic acid. The Col-0 reference strain can be quite different from a large proportion of the natural accessions of the species, illustrating a severe caveat of relying on a single reference strain in model species and drawing generalizations from it. Using GWAS, we further identify a large number of loci underlying the variation of responses to plant hormones, in particular to abscisic acid, find links between local adaptation and root responses to hormones, and finally using mutants for GWAS candidate genes, identify novel players involved in regulating hormone responses.

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