A Novel U-Box Protein Gene from “Zuoshanyi” Grapevine (Vitis amurensis Rupr. cv.) Involved in Cold Responsive Gene Expression in Arabidopsis thanliana

摘要

Ubiquitination plays an important role in posttranscriptional modification of proteins. As a component of the ubiquitin conjugation system, E3 ligase is believed to be a key element determining the substrate specificity of ubiquitination. In this research, a novel putative U-box type E3 ligase VaPUB (plant U-box protein) was isolated from a very cold-hardy “Zuoshanyi” (Vitis amurensis Rupr. cv.) grapevine. Real-time PCR demonstrated that PUB was upregulated by cold stress and expressed more strongly in cold-tolerant grapevines than in cold-sensitive grapevines. In cold-hardy V. amurensis Zuoshanyi grapevine, the expression of PUB was upregulated by cold in all tissues, although more dramatic increases were found in the leaves and shoot tips than in the roots or stems. Over-expression of VaPUB in Arabidopsis resulted in an enhancement of cold and salt stress tolerance. The transcription factors, CBF1/DREB1B and CBF3/DREB1A, and cold inducing genes, COR15A, COR47, KIN1, RD29A, and SuSy, were expressed in a higher level in VaPUB transgenic plants than the wild type. In contrast, the expression of transcription factor CBF2/DREB1C was repressed by VaPUB. These results demonstrated that VaPUB enhanced plant cold and salt stress tolerance and its over-expression affected the expression of cold responsive genes.