title: Arabidopsis RAV1 transcription factor, phosphorylated by SnRK2 kinases, regulates the expression of ABI3, ABI4, and ABI5 during seed germination and early seedling development.
abstract: The phytohormone abscisic acid (ABA) modulates a number of processes during plant growth and development. In this study, the molecular mechanism of Arabidopsis RAV (Related to ABI3/VP1) transcription factor RAV1 involving ABA signaling was investigated. RAV1-underexpressing lines were more sensitive to ABA than wild-type plants during seed germination and early seedling development, whereas RAV1-overexpressing lines showed strong ABA-insensitive phenotypes. Overexpression of RAV1 repressed ABI3, ABI4, and ABI5 expression, and RAV1 bound to the ABI3, ABI4, and ABI5 promoters in vitro and in vivo, indicating that RAV1 directly down-regulates the expression of ABI3, ABI4, and ABI5. The interruption of ABI5 function in RAV1-U abi5 plants abolished the ABA-hypersensitive phenotype of RAV1-U plants, demonstrating that ABI5 is epistatic to RAV1. RAV1 interacted with SNF1-RELATED PROTEIN KINASE SnRK2.2, SnRK2.3 and SnRK2.6 in the nucleus. In vitro kinase assays showed that SnRK2.2, SnRK2.3 and SnRK2.6 phosphorylated RAV1. Transient expression assays revealed that SnRK2.2, SnRK2.3 and SnRK2.6 reduced the RAV1-dependent repression of ABI5, and the ABA-insensitive phenotype of the RAV1-overexpressing line was impaired by overexpression of SnRK2.3 in the RAV1 OE3 plants. Together, these results demonstrated that the Arabidopsis RAV1 transcription factor plays an important role in ABA signaling by modulating the expression of ABI3, ABI4, and ABI5, and that its activity is negatively affected by SnRK2s.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, National Plant Gene Research Centre (Beijing), China Agricultural University, Beijing, 100193, China.
authors.forename: Cui-Zhu
authors.initials: CZ
authors.lastname: Feng
authors.forename: Yun
authors.initials: Y
authors.lastname: Chen
authors.forename: Cun
authors.initials: C
authors.lastname: Wang
authors.forename: You-Han
authors.initials: YH
authors.lastname: Kong
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Wu
authors.forename: Yi-Fang
authors.initials: YF
authors.lastname: Chen
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004843:Epistasis, Genetic; D018506:Gene Expression Regulation, Plant; D018525:Germination; D010766:Phosphorylation; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D036226:Seedlings / Q000235:genetics / Q000254:growth & development*; D012639:Seeds / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C091601:ABI3 protein, Arabidopsis; C470421:ABI4 protein, Arabidopsis; C409743:ABI5 protein, Arabidopsis; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; C117695:RAV1 protein, Arabidopsis; C492978:SnRK2 protein, Arabidopsis; D014157:Transcription Factors; D000040:Abscisic Acid; D017346:Protein Serine-Threonine Kinases
keywords: ABI3; ABI4; ABI5; Arabidopsis thaliana; RAV1 transcription factor; SnRK2 kinase; seed germination