Expression of a Grape VqSTS36-Increased Resistance to Powdery Mildew and Osmotic Stress in Arabidopsis but Enhanced Susceptibility to Botrytis cinerea in Arabidopsis and Tomato

Stilbene synthase genes make a contribution to improving the tolerances of biotic and abiotic stress in plants. However, the mechanisms mediated by these STS genes remain unclear. To provide insight into the role of STS genes defense against biotic and abiotic stress, we overexpressed VqSTS36 in Arabidopsis thaliana and tomato (Micro-Tom) via Agrobacterium-mediated transformation. VqSTS36-transformed Arabidopsis lines displayed an increased resistance to powdery mildew, but both VqSTS36-transformed Arabidopsis and tomato lines showed the increased susceptibility to Botrytis cinerea. Besides, transgenic Arabidopsis lines were found to confer tolerance to salt and drought stress in seed and seedlings. When transgenic plants were treated with a different stress, qPCR assays of defense-related genes in transgenic Arabidopsis and tomato suggested that VqSTS36 played a specific role in different phytohormone-related pathways, including salicylic acid, jasmonic acid, and abscisic acid signaling pathways. All of these results provided a better understanding of the mechanism behind the role of VqSTS36 in biotic and abiotic stress.