VqMAPK3/VqMAPK6, VqWRKY33, and <i>VqNSTS3</i> constitute a regulatory node in enhancing resistance to powdery mildew in grapevine

Abstract

Grapevine powdery mildew is caused by <i>Erysiphe necator</i>, which seriously harms grape production in the world. Stilbene synthase makes phytoalexins that contribute to the resistance of grapevine against powdery mildew. A novel <i>VqNSTS3</i> was identified and cloned from Chinese wild <i>Vitis quinquangularis</i> accession Danfeng-2. The novel <i>VqNSTS3</i> was transferred into susceptible 'Thompson Seedless' by <i>Agrobacterium</i>-mediated transformation. The transgenic plants showed resistance to the disease and activated other resistance-related genes. <i>VqNSTS3</i> expression in grapevine is regulated by VqWRKY33, and which binds to TTGACC in the <i>VqNSTS3</i> promoter. Furthermore, VqWRKY33 was phosphorylated by VqMAPK3/VqMAPK6 and thus led to enhanced signal transduction and increased <i>VqNSTS3</i> expression. <i>Pro</i><i>VqNSTS3::VqNSTS3</i>-GFP of transgenic <i>VqNSTS3</i> in <i>Arabidopsis thaliana</i> was observed to move to and wrap the pathogen's haustoria and block invasion by <i>Golovinomyces cichoracearum</i>. These results demonstrate that stilbene accumulation of novel <i>VqNSTS3</i> of the Chinese wild <i>Vitis quinquangularis</i> accession Danfeng-2 prevented pathogen invasion and enhanced resistance to powdery mildew. Therefore, <i>VqNSTS3</i> can be used in generating powdery mildew-resistant grapevines.