title: Activated expression of WRKY57 confers drought tolerance in Arabidopsis.
abstract: Drought is one of the most serious environmental factors that limit the productivity of agricultural crops worldwide. However, the mechanism underlying drought tolerance in plants is unclear. WRKY transcription factors are known to function in adaptation to abiotic stresses. By screening a pool of WRKY-associated T-DNA insertion mutants, we isolated a gain-of-function mutant, acquired drought tolerance (adt), showing improved drought tolerance. Under drought stress conditions, adt accumulated higher levels of ABA than wild-type plants. Stomatal aperture analysis indicated that adt was more sensitive to ABA than wild-type plants. Molecular genetic analysis revealed that a T-DNA insertion in adt led to activated expression of a WRKY gene that encodes the WRKR57 protein. Constitutive expression of WRKY57 also conferred similar drought tolerance. Consistently with the high ABA content and enhanced drought tolerance, three stress-responsive genes (RD29A, NCED3, and ABA3) were up-regulated in adt. ChIP assays demonstrated that WRKY57 can directly bind the W-box of RD29A and NCED3 promoter sequences. In addition, during ABA treatment, seed germination and early seedling growth of adt were inhibited, whereas, under high osmotic conditions, adt showed a higher seed germination frequency. In summary, our results suggested that the activated expression of WRKY57 improved drought tolerance of Arabidopsis by elevation of ABA levels. Establishment of the functions of WRKY57 will enable improvement of plant drought tolerance through gene manipulation approaches.
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223,  China.
authors.forename: Yanjuan
authors.initials: Y
authors.lastname: Jiang
authors.forename: Gang
authors.initials: G
authors.lastname: Liang
authors.forename: Diqiu
authors.initials: D
authors.lastname: Yu
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000222:Adaptation, Physiological / Q000187:drug effects; D000483:Alleles; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D049308:Dioxygenases / Q000235:genetics; D055864:Droughts; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018525:Germination / Q000187:drug effects; D009154:Mutation; D059372:Nucleotide Motifs / Q000235:genetics; D009995:Osmosis / Q000187:drug effects; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D012492:Salts / Q000494:pharmacology; D012639:Seeds / Q000187:drug effects / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D010940:Plant Proteins; C520629:RD29a protein, Arabidopsis; D012492:Salts; D014157:Transcription Factors; C584399:WRKY57 protein, Arabidopsis; D000040:Abscisic Acid; D049308:Dioxygenases; C109043:9-cis-epoxy-carotenoid dioxygenase