Vdwrky70 Gene Induces Defense Response Against Grape White Rot in Vitis Davidii Through the Salicylic Acid Signaling Pathway

Grapevine is cultivated in various regions of the world, majority of the cultivars are obtained from European Vitis vinifera, which are vulnerable to different diseases especially white rot caused by the fungus Coniella diplodiella and its disease resistance can differ significantly among different species of grapevine; however, the molecular mechanism of disease resistance still unknown and have not been studied thoroughly. In this study, Chinese wild grapevine (V. davidii ‘0943’) showed rapid hypersensitive response against C. diplodiella, while V. vinifera exhibited spreading tissue necrosis on leaves. The expression of VdWRKY70, followed by VdPR1 and VdNPR1 were increased significantly in V. davidii than in V. vinifera during C. diplodiella infection. So, different hormones were measured form V. davidii through UPLC-ESI-MS/MS in which salicylic acid (SA and SAG) contents were significantly up-regulated, jasmonic acid (JA and JA-Ile) and cytokinins (iPG7 and IPR) were significantly down-regulated after different time points of C. diplodiella inoculation. The ectopic overexpression of VdWRKY70 localized in the nucleus in Arabidopsis thaliana improved plant resistance to C. diplodiella, Golovinomyces cichoracearum, and Pseudomonas syringae pv. tomato DC3000. In VdWRKY70 overexpressed transgenic A. thaliana, AtNPR1 and AtPR1 genes were up-regulated and the SA contents were also increased correspondingly. Moreover, the transient overexpression of VdWRKY70 in V. vinifera showed higher resistance and endogenous level of SA as well as VvPR1 and VvNPR1 gene expression increased in response to C. diplodiella infection. Overall, these results concluded that V. davidii resisted C. diplodiella infection by switching on the VdWRKY70 gene via the SA-signaling pathway.