title: The cold-induced basic helix-loop-helix transcription factor gene MdCIbHLH1 encodes an ICE-like protein in apple.
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 the cold tolerance response in apple.
authors.affiliation: The State Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Feng
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhao
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Zhao
authors.forename: Yu
authors.initials: Y
authors.lastname: Qiao
authors.forename: Xing-Bin
authors.initials: XB
authors.lastname: Xie
authors.forename: Hui-Feng
authors.initials: HF
authors.lastname: Li
authors.forename: Yu-Xin
authors.initials: YX
authors.lastname: Yao
authors.forename: Chun-Xiang
authors.initials: CX
authors.lastname: You
authors.forename: Yu-Jin
authors.initials: YJ
authors.lastname: Hao
mesh_terms: D000064:Acclimatization; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D003080:Cold Temperature; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D027845:Malus / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D059748:Proteolysis; D017422:Sequence Analysis, DNA; D013312:Stress, Physiological; D013379:Substrate Specificity; D058207:Sumoylation; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D010940:Plant Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C114578:DREB1A protein, Arabidopsis