Grapevine trunk diseases (GTDs) threaten the economic balance of viticulture worldwide. Since the ban of sodium arsenite, no effective treatment exists against the responsible fungi. While biocontrol is promoted in Europe, no solution for GTDs has yet been proposed or implemented in vineyards. During preliminary tests, bacterial communities isolated from the sap of a healthy grapevine showed potential for biocontrol applications in grapevine protection, exhibiting antifungal properties and the ability to enhance nutrient uptake. This project aims to i) understand how to ensure the long-term establishment of seven of these bacteria in grapevines and ii) characterize their antifungal activities. i) Some of these seven bacteria have already been shown to penetrate the roots and colonize the aerial parts of in vitro grapevine plants. Furthermore, the molecular dialogues between these bacteria and grapevine are currently investigated to understand the mechanisms involved in the establishment of the microbial community. ii) Some bacterial cocktails can inhibit up to 90% of fungal growth in in vitro confrontations with GTDs fungi and also reduce necrotic areas in woody tissue. The volatile antifungal compounds involved in these phytoprotective activities will soon be identified using gas chromatography-mass spectrometry. In fine, this project seeks to offer a new biocontrol opportunity for grapevine through the establishment of an indigenous bacterial microbiome.
