Study of grapevine endophytes’ interaction with the host and their potential as biocontrol agents as sustainable alternative to agrochemicals

In sustainable vineyard management, biocontrol agents (BCAs) offer a promising alternative to chemical pesticides. This study focuses on characterizing endophytes isolated from grapevines in different regions of northern Italy for (i) their effectiveness against Botrytis cinerea through in vitro tests and (ii) their capability to survive in the presence of copper and other commercial fungicides with the final goal of investigating their possible future application for an integrated approach in vineyard. Aureobasidium pullulans strains ED203, ED206, ED217, and ED221 demonstrated significant antagonistic activity toward B. cinerea, while Bacillus velezensis ED163 showed the highest levels of pathogen inhibition. Volatile organic compounds (VOCs) analysis identified three distinct microbial clusters based on BCAs volatile profiles, highlighting the production of antifungal compounds such as alcohols, esters, and terpenes to counteract the pathogen growth. The investigated BCAs showed tolerance to high concentrations of copper (up to 100 mg/L) and the fungicide SWITCH (1 g/L), but they were sensitive to a standard oenological dose of sulfur dioxide (50 mg/L). Finally, in vivo tests on grapevine leaves confirmed the ability of B. velezensis and A. pullulans strains ED203 and ED221 candidates to effectively reduce the mycelium infection on plant tissue standing out as strong candidates for pest management. The interaction between BCAs with the host was confirmed through leaves cell culture use, highlighting the capability of the best candidate selected in the study to modulate plant response in presence of pathogen.