the cold-induced basic helix-loop-helix transcription factor gene mdcibhlh1 encodes an ice-like protein in apple对低温的反应可以基本helix-loop-helix mdcibhlh1转录因子基因编码一个蛋白质在苹果像冰一样.pdf

Feng et al. BMC Plant Biology 2012, 12:22 /1471-2229/12/22 RESEARCH ARTICLE Open Access The cold-induced basic helix-loop-helix transcription factor gene MdCIbHLH1 encodes an ICE-like protein in apple 1 1 2 1 1 3 1 Xiao-Ming Feng , Qiang Zhao , Ling-Ling Zhao , Yu Qiao , Xing-Bin Xie , Hui-Feng Li , Yu-Xin Yao , Chun-Xiang You1 and Yu-Jin Hao1* Abstract Background: Plant growth is greatly affected by low temperatures, and the expression of a number of genes is induced by cold stress. Although many genes in the cold signaling pathway have been identified in Arabidopsis, little is known about the transcription factors involved in the cold stress response in apple. Results: Here, we show that the apple bHLH (basic helix-loop-helix) gene MdCIbHLH1 (Cold-Induced bHLH1), which encodes an ICE-like protein, was noticeably induced in response to cold stress. The MdCIbHLH1 protein specifically bound to the MYC recognition sequences in the AtCBF3 promoter, and MdCIbHLH1 overexpression enhanced cold tolerance in transgenic Arabidopsis. In addition, the MdCIbHLH1 protein bound to the promoters of MdCBF2 and favorably contributed to cold tolerance in transgenic apple plants by upregulating the expression of MdCBF2 through the CBF (C-repeat-binding factor) pathway. Our findings indicate that MdCIbHLH1 functions in stress tolerance in different species. For example, ectopic MdCIbHLH1 expression conferred enhanced chilling tolerance in transgenic tobacco. Finally, we observed that cold induces the degradation of the MdCIbHLH1 protein in apple and that this degradation was potentially mediated by ubiquitination and sumoylation. Conclusions: Based on these findings, MdCIbHLH1 encodes a transcription factor that is important for