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Plant Signal Behav. 2013 Mar;8(3):e23455. doi: 10.4161/psb.23455. Epub 2013 Jan 8.

A novel abi5 allele reveals the importance of the conserved Ala in the C3 domain for regulation of downstream genes and salt tolerance during germination in Arabidopsis.

Author information

1
Department of BioScience; Tokyo University of Agriculture; Tokyo, Japan; Department of Applied Biology and Chemistry; Faculty of Applied Biosciences; Tokyo University of Agriculture; Tokyo, Japan.

Abstract

Abscisic acid (ABA) signal transduction during Arabidopsis seed development and germination requires a Group A bZIP transcription factor encoded by ABA INSENSITIVE5 (ABI5). In addition to the basic leucine zipper DNA binding domain, Group A bZIPs are characterized by three N-terminal conserved regions (C1, C2 and C3) and one C-terminal conserved region (C4). These conserved regions are considered to play roles in ABI5 functions; however, except for the phosphorylation site, the importance of the highly conserved amino acids is unclear. Here, we report a novel abi5 recessive allele (abi5-9) that encodes an intact ABI5 protein with one amino acid substitution (A214G) in the C3 domain. The abi5-9 plants showed ABA insensitivity during germination and could germinate on medium containing 175 mM NaCl or 500 mM mannitol. Em1 and Em6--both encoding late embryogenesis abundant (LEA) proteins and directly targeted by ABI5 regulation--were expressed at very low levels in abi5-9 plants compared with the wild type. In yeast, the abi5-9 protein exhibited greatly reduced interaction with ABI3 compared with ABI5. These data suggest that Ala214 in ABI5 contributes to the function of ABI5 via its interaction with ABI3.

KEYWORDS:

ABA; abiotic stress tolerance; abscisic acid; gene expression; growth control; hormone signaling; plant signaling; transcriptional regulation

PMID:
23299338
PMCID:
PMC3676515
DOI:
10.4161/psb.23455
[Indexed for MEDLINE]
Free PMC Article

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