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b HLH 122 is important for drought and osmotic stress resistance in A rabidopsis and in the repression of ABA catabolism
Author(s) -
Liu Wenwen,
Tai Huanhuan,
Li Songsong,
Gao Wei,
Zhao Meng,
Xie Chuanxiao,
Li WenXue
Publication year - 2014
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12607
Subject(s) - mutant , biology , electrophoretic mobility shift assay , transcription factor , wild type , chromatin immunoprecipitation , abiotic stress , osmotic shock , microbiology and biotechnology , psychological repression , gene , gene expression , biochemistry , promoter
Summary Although proteins in the basic helix‐loop‐helix (b HLH ) family are universal transcription factors in eukaryotes, the biological roles of most b HLH family members are not well understood in plants. The A rabidopsis thaliana b HLH 122 transcripts were strongly induced by drought, N a C l and osmotic stresses, but not by ABA treatment. Promoter:: GUS analysis showed that b HLH 122 was highly expressed in vascular tissues and guard cells. Compared with wild‐type ( WT ) plants, transgenic plants overexpressing b HLH 122 displayed greater resistance to drought, N a C l and osmotic stresses. In contrast, the bhlh122 loss‐of‐function mutant was more sensitive to N a C l and osmotic stresses than were WT plants. Microarray analysis indicated that b HLH 122 was important for the expression of a number of abiotic stress‐responsive genes. In electrophoretic mobility shift assay and chromatin immunoprecipitation assays, b HLH 122 could bind directly to the G ‐box/ E ‐box cis ‐elements in the CYP 707 A 3 promoter, and repress its expression. Further, up‐regulation of b HLH 122 substantially increased cellular ABA levels. These results suggest that b HLH 122 functions as a positive regulator of drought, NaCl and osmotic signaling.