Overexpression of a grapevine VqWRKY2 transcription factor in Arabidopsis thaliana increases resistance to powdery mildew

Powdery mildew (PM) disease of grapevine is a significant production problem in most areas of the world in which grapes are grown. The disease is caused by the fungus Erysiphe necator Schw. [syn. Uncinula necator (Schw.) Burr.]. Members of the WRKY transcription factor are key regulators of plant immunity to PM. In this study, the level of VqWRKY2 transcript was quickly induced in response to E. necator inoculation and levels increased in most organs and tissues. We isolated VqWRKY2 from an accession of the Chinese wild grape, Vitis quinquangularis, Shang-24, which shows high resistance to PM. The results indicate that VqWRKY2 localized in the nucleus and showed transcriptional activation in yeast is a Group I protein of the WRKY family and is similar to Citrus sinensis CsWRKY2. We reveal that overexpression of VqWRKY2 in Arabidopsis enhances resistance to PM that is associated with increased cell death and expression of nonexpressor of pathogenesis-related genes 1 (NPR1) in the salicylic acid (SA) signaling pathway. The physical interaction between VqWRKY2 and VqWRKY46 was demonstrated by the Yeast Two-Hybrid, Bimolecular Fluorescence Complementation and Pull-down assay. Our results contribute to the development of the theoretical basis which will help support further research on the development of new disease-resistant genotypes of grapevine. Overexpression of grapevine VqWRKY2 in Arabidopsis thaliana enhances resistance to powdery mildew by increasing cell death and activating the SA signaling pathway.