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Arabidopsis RAV 1 transcription factor, phosphorylated by S n RK 2 kinases, regulates the expression of ABI 3 , ABI 4 , and ABI 5 during seed germination and early seedling development
Author(s) -
Feng CuiZhu,
Chen Yun,
Wang Cun,
Kong YouHan,
Wu WeiHua,
Chen YiFang
Publication year - 2014
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12670
Subject(s) - abscisic acid , arabidopsis , transcription factor , kinase , phosphorylation , phenotype , biology , microbiology and biotechnology , chemistry , mutant , genetics , gene
Summary The phytohormone abscisic acid ( ABA ) modulates a number of processes during plant growth and development. In this study, the molecular mechanism of A rabidopsis RAV (Related to ABI 3/ VP 1) transcription factor RAV 1 involving ABA signaling was investigated. RAV 1 ‐underexpressing lines were more sensitive to ABA than wild‐type plants during seed germination and early seedling development, whereas RAV 1 ‐overexpressing lines showed strong ABA ‐insensitive phenotypes. Overexpression of RAV 1 repressed ABI 3 , ABI 4 , and ABI 5 expression, and RAV 1 bound to the ABI 3 , ABI 4 , and ABI 5 promoters in vitro and in vivo , indicating that RAV 1 directly down‐regulates the expression of ABI 3 , ABI 4 , and ABI 5 . The interruption of ABI 5 function in RAV 1‐ U abi5 plants abolished the ABA ‐hypersensitive phenotype of RAV 1‐ U plants, demonstrating that ABI 5 is epistatic to RAV 1 . RAV 1 interacted with SNF 1‐ RELATED PROTEIN KINASE S n RK 2.2, S n RK 2.3 and S n RK 2.6 in the nucleus. In vitro kinase assays showed that S n RK 2.2, S n RK 2.3 and S n RK 2.6 phosphorylated RAV 1. Transient expression assays revealed that S n RK 2.2, S n RK 2.3 and S n RK 2.6 reduced the RAV 1‐dependent repression of ABI 5 , and the ABA ‐insensitive phenotype of the RAV 1 ‐overexpressing line was impaired by overexpression of S n RK 2.3 in the RAV 1 OE 3 plants. Together, these results demonstrated that the A rabidopsis RAV 1 transcription factor plays an important role in ABA signaling by modulating the expression of ABI 3 , ABI 4 , and ABI 5 , and that its activity is negatively affected by S n RK 2s.