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Arabidopsis Atb HLH 112 regulates the expression of genes involved in abiotic stress tolerance by binding to their E‐box and GCG ‐box motifs
Author(s) -
Liu Yujia,
Ji Xiaoyu,
Nie Xianguang,
Qu Min,
Zheng Lei,
Tan Zilong,
Zhao Huimin,
Huo Lin,
Liu Shengnan,
Zhang Bing,
Wang Yucheng
Publication year - 2015
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.13387
Subject(s) - transcription factor , abiotic stress , arabidopsis , gene , abscisic acid , activator (genetics) , biology , microbiology and biotechnology , genetics , mutant
Summary Plant basic helix–loop–helix ( bHLH ) transcription factors play essential roles in abiotic stress tolerance. However, most bHLH s have not been functionally characterized. Here, we characterized the functional role of a bHLH transcription factor from Arabidopsis , Atb HLH 112, in response to abiotic stress. Atb HLH 112 is a nuclear‐localized protein, and its nuclear localization is induced by salt, drought and abscisic acid ( ABA ). In addition, Atb HLH 112 serves as a transcriptional activator, with the activation domain located at its N‐terminus. In addition to binding to the E‐box motifs of stress‐responsive genes, Atb HLH 112 binds to a novel motif with the sequence ‘ GG [ GT ] CC [ GT ][ GA ][ TA ]C’ ( GCG ‐box). Gain‐ and loss‐of‐function analyses showed that the transcript level of Atb HLH 112 is positively correlated with salt and drought tolerance. Atb HLH 112 mediates stress tolerance by increasing the expression of P5 CS genes and reducing the expression of P5 CDH and Pro DH genes to increase proline levels. Atb HLH 112 also increases the expression of POD and SOD genes to improve reactive oxygen species ( ROS ) scavenging ability. We present a model suggesting that Atb HLH 112 is a transcriptional activator that regulates the expression of genes via binding to their GCG ‐ or E‐boxes to mediate physiological responses, including proline biosynthesis and ROS scavenging pathways, to enhance stress tolerance.