Ectopic expression of a grapevine transcription factor VvWRKY11 contributes to osmotic stress tolerance in Arabidopsis

Plant WRKY transcriptional factors play an important role in response to biotic and abiotic stresses. In this study, a WRKY transcription factor was isolated from grapevine. This transcription factor showed 66% and 58% identity at the DNA and amino acid sequence levels, respectively, with Arabidopsis AtWRKY11 genes, and was therefore designated VvWRKY11. Phylogenetic analysis and structure comparison indicated that VvWRKY11 protein belongs to group IIc. The VvWRKY11 protein was shown to be located in the nucleus based on green fluorescent protein analysis. Yeast one-hybrid analysis further indicated that VvWRKY11 protein binds specifically to the W-box element. The expression profile of VvWRKY11 in response to treatment with phytohormone salicylic acid or pathogen Plasmopara viticola is rapid and transient. Transgenic Arabidopsis seedlings overexpressing VvWRKY11 showed higher tolerance to water stress induced by mannitol than wild-type plants. These results clearly demonstrated that the VvWRKY11 gene is involved in the response to dehydration stress. In addition, the role of VvWRKY11 protein in regulating the expression of two stress response genes, AtRD29A and AtRD29B, is also discussed.