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SRK2C, a SNF1-related protein kinase 2, improves drought tolerance by controlling stress-responsive gene expression in Arabidopsis thaliana.

ABSTRACT: Protein phosphorylation/dephosphorylation are major signaling events induced by osmotic stress in higher plants. Here, we showed that a SNF1-related protein kinase 2 (SnRK2), SRK2C, is an osmotic-stress-activated protein kinase in Arabidopsis thaliana that can significantly impact drought tolerance of Arabidopsis plants. Knockout mutants of SRK2C exhibited drought hypersensitivity in their roots, suggesting that SRK2C is a positive regulator of drought tolerance in Arabidopsis roots. Additionally, transgenic plants with CaMV35S promoter::SRK2C-GFP displayed higher overall drought tolerance than control plants. Whereas stomatal regulation in 35S::SRK2C-GFP plants was not altered, microarray analysis revealed that their drought tolerance coincided with up-regulation of many stress-responsive genes, for example, RD29A, COR15A, and DREB1A/CBF3. From these results, we concluded that SRK2C is capable of mediating signals initiated during drought stress, resulting in appropriate gene expression. Our present study reveals new insights around signal output from osmotic-stress-activated SnRK2 protein kinase as well as supporting feasibility of manipulating SnRK2 toward improving plant osmotic-stress tolerance.

SUBMITTER: Umezawa T

PROVIDER: S-EPMC535404 | biostudies-literature | 2004 Dec

REPOSITORIES: biostudies-literature

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SRK2C, a SNF1-related protein kinase 2, improves drought tolerance by controlling stress-responsive gene expression in Arabidopsis thaliana.

Umezawa Taishi T Yoshida Riichiro R Maruyama Kyonoshin K Yamaguchi-Shinozaki Kazuko K Shinozaki Kazuo K

Proceedings of the National Academy of Sciences of the United States of America 20041123 49

Protein phosphorylation/dephosphorylation are major signaling events induced by osmotic stress in higher plants. Here, we showed that a SNF1-related protein kinase 2 (SnRK2), SRK2C, is an osmotic-stress-activated protein kinase in Arabidopsis thaliana that can significantly impact drought tolerance of Arabidopsis plants. Knockout mutants of SRK2C exhibited drought hypersensitivity in their roots, suggesting that SRK2C is a positive regulator of drought tolerance in Arabidopsis roots. Additionall ...[more]

PMID: 15561775

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Project description:BackgroundStrawberry (Fragaria × ananassa Duch.) is an important fruit crop worldwide. It was particularly sensitive to drought stress because of their fibrous and shallow root systems. Mutant rty of Arabidopsis thaliana ROOTY (RTY) results in increased endogenous auxin levels, more roots, and shoot growth. It is still unclear whether the rty gene improves stress tolerance in strawberry.Resultsrty gene was isolated from Arabidopsis thaliana and placed under the control of the cauliflower mosaic virus (CaMV) 35S promoter in the pBI121-rty binary vector carrying the selectable marker of neomycin phosphotransferase II (NPT II). Seven transgenic lines were confirmed by PCR and western blot analysis. Accumulations of IAA and ABA were significantly increased in the transgenic plants. The endogenous IAA contents were 46.5 ng g- 1 and 66.0 ng g- 1in control and transgenic plants respectively. The endogenous ABA contents in the control plant were 236.3 ng g- 1 and in transgenic plants were 543.8 ng g- 1. The production of adventitious roots and trichomes were enhanced in the transgenic plants. Furthermore, transcript levels of the genes including IAA and ABA biosynthetic, and stress-responsive genes, were higher in the transgenic plants than in the control plants under drought conditions. Water use efficiency and a reduced water loss rate were enhanced in the transgenic strawberry plants. Additionally, peroxidase and catalase activities were significantly higher in the transgenic plants than in the control plants. The experiment results revealed a novel function for rty related to ABA and drought responses.ConclusionsThe rty gene improved hormone-mediated drought tolerance in transgenic strawberry. The heterologous expression of rty in strawberry improved drought tolerance by promoting auxin and ABA accumulation. These phytohormones together brought about various physiological changes that improved drought tolerance via increased root production, trichome density, and stomatal closure. Our results suggested that a transgenic approach can be used to overcome the inherent trade-off between plant growth and drought tolerance by enhancing water use efficiency and reducing water loss rate under water shortage conditions.

Project description:BACKGROUND:Cuticular wax plays important role in protecting plants from drought stress. In Arabidopsis WRI4 improves drought tolerance by regulating the biosynthesis of fatty acids and cuticular wax. Cyperus esculentus (yellow nutsedge) is a tough weed found in tropical and temperate zones as well as in cooler regions. In the current study, we report the molecular cloning of a WRI4-like gene from Cyperus esculentus and its functional characterization in Arabidopsis. RESULTS:Using RACE PCR, full-length WRI-like gene was amplified from yellow nutsedge. Phylogenetic analyses and amino acid comparison suggested it to be a WRI4-like gene. According to the tissue-specific expression data, the highest expression of WRI4-like gene was found in leaves, followed by roots and tuber. Transgenic Arabidopsis plants expressing nutsedge WRI4-like gene manifested improved drought stress tolerance. Transgenic lines showed significantly reduced stomatal conductance, transpiration rate, chlorophyll leaching, water loss and improved water use efficiency (WUE). In the absence of drought stress, expression of key genes for fatty acid biosynthesis was not significantly different between transgenic lines and WT while that of cuticular wax biosynthesis genes was significantly higher in transgenic lines than WT. The PEG-simulated drought stress significantly increased expression of key genes for fatty acid as well as wax biosynthesis in transgenic Arabidopsis lines but not in WT plants. Consistent with the gene expression data, cuticular wax load and deposition was significantly higher in stem and leaves of transgenic lines compared with WT under control as well as drought stress conditions. CONCLUSIONS:WRI4-like gene from Cyperus esculentus improves drought tolerance in Arabidopsis probably by promoting cuticular wax biosynthesis and deposition. This in turn lowers chlorophyll leaching, stomatal conductance, transpiration rate, water loss and improves water use efficiency under drought stress conditions. Therefore, CeWRI4-like gene could be a good candidate for improving drought tolerance in crops.

Project description:BackgroundTrehalose-6-phosphate phosphatases (TPPs), which are encoded by members of the TPP gene family, can improve the drought tolerance of plants. However, the molecular mechanisms underlying the dynamic regulation of TPP genes during drought stress remain unclear. In this study, we explored the function of an Arabidopsis TPP gene by conducting comparative analyses of a loss-of-function mutant and overexpression lines.ResultsThe loss-of-function mutation of Arabidopsis thaliana TPPF, a member of the TPP gene family, resulted in a drought-sensitive phenotype, while a line overexpressing TPPF showed significantly increased drought tolerance and trehalose accumulation. Compared with wild-type plants, tppf1 mutants accumulated more H2O2 under drought, while AtTPPF-overexpressing plants accumulated less H2O2 under drought. Overexpression of AtTPPF led to increased contents of trehalose, sucrose, and total soluble sugars under drought conditions; these compounds may play a role in scavenging reactive oxygen species. Yeast one-hybrid and luciferase activity assays revealed that DREB1A could bind to the DRE/CRT element within the AtTPPF promoter and activate the expression of AtTPPF. A transcriptome analysis of the TPPF-overexpressing plants revealed that the expression levels of drought-repressed genes involved in electron transport activity and cell wall modification were upregulated, while those of stress-related transcription factors related to water deprivation were downregulated. These results indicate that, as well as its involvement in regulating trehalose and soluble sugars, AtTPPF is involved in regulating the transcription of stress-responsive genes.ConclusionAtTPPF functions in regulating levels of trehalose, reactive oxygen species, and sucrose levels during drought stress, and the expression of AtTPPF is activated by DREB1A in Arabidopsis. These findings shed light on the molecular mechanism by which AtTPPF regulates the response to drought stress.

Dataset Information

SRK2C, a SNF1-related protein kinase 2, improves drought tolerance by controlling stress-responsive gene expression in Arabidopsis thaliana.

Publications

SRK2C, a SNF1-related protein kinase 2, improves drought tolerance by controlling stress-responsive gene expression in Arabidopsis thaliana.

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