title: An ABA down-regulated bHLH transcription repressor gene, bHLH129 regulates root elongation and ABA response when overexpressed in Arabidopsis.
abstract: Plant hormone abscisic acid (ABA) plays a crucial role in modulating plant responses to environmental stresses. Basic helix-loop-helix (bHLH) transcription factors are one of the largest transcription factor families that regulate multiple aspects of plant growth and development, as well as of plant metabolism in Arabidopsis. Several bHLH transcription factors have been shown to be involved in the regulation of ABA signaling. We report here the characterization of bHLH129, a bHLH transcription factor in Arabidopsis. We found that the expression level of bHLH129 was reduced in response to exogenously applied ABA, and elevated in the ABA biosynthesis mutant aba1-5. Florescence observation of transgenic plants expressing bHLH129-GFP showed that bHLH129 was localized in the nucleus, and transient expression of bHLH129 in protoplasts inhibited reporter gene expression. When expressed in Arabidopsis under the control of the 35S promoter, bHLH129 promoted root elongation, and the transgenic plants were less sensitivity to ABA in root elongation assays. Quantitative RT-PCR results showed that ABA response of several genes involved in ABA signaling, including ABI1, SnRK2.2, SnRK2.3 and SnRK2.6 were altered in the transgenic plants overexpressing bHLH129. Taken together, our study suggests that bHLH129 is a transcription repressor that negatively regulates ABA response in Arabidopsis.
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun, Jilin 130024, China.
authors.forename: Hainan
authors.initials: H
authors.lastname: Tian
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun, Jilin 130024, China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Guo
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun, Jilin 130024, China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Dai
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun, Jilin 130024, China.
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun, Jilin 130024, China.
authors.forename: Kaijie
authors.initials: K
authors.lastname: Zheng
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun, Jilin 130024, China.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun, Jilin 130024, China.
authors.forename: Shucai
authors.initials: S
authors.lastname: Wang
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000096:biosynthesis* / Q000235:genetics; D051792:Basic Helix-Loop-Helix Proteins / Q000096:biosynthesis* / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D000040:Abscisic Acid; D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D012097:Repressor Proteins