Biocontrol potential of grapevine endophytes against grapevine trunk pathogens

Grapevine Trunk Diseases (GTDs) are a major challenge to the grape industry worldwide. GTDs are responsible for considerable loss of quality, production, and vineyard longevity. Seventy five percent of Chilean vineyards are estimated to be affected by GTDs. GTDs are complex diseases caused by several species of fungi, including Neofusicoccum parvum, Diplodia seriata, and Phaeomoniella chlamydospora. In this study, we report the isolation of 169 endophytic and 209 epiphytic fungi from grapevines grown under organic and conventional farming in Chile. Multiple isolates of Clonostachys rosea, Trichoderma sp., Purpureocillium lilacium, Epiccocum nigrum, Cladosporium sp., and Chaetomium sp. were evaluated for their potential of biocontrol activity against fungal trunk pathogens. Tests were carried out using two dual-culture-plate methods with multiple media types, including agar containing grapevine wood extract to simulate in planta nutrient conditions. Significant pathogen growth inhibition was observed by all isolates tested. C. rosea showed 98.2% inhibition of all pathogens in presence of grapevine wood extract. We observed 100% pathogen growth inhibition when autoclaved lignified grapevine shoots were pre-inoculated with either C. rosea strains or Trichoderma sp.. Overall these results show that C. rosea strains isolated from grapevines are promising biocontrol agents against GTDs.