Dissecting positive or negative effects of abiotic stress on grapevine self-protection induced by Trichoderma harzianum T39

Downy mildew is one of the most destructive grapevine diseases, and its control is based on the application of fungicides. There is increasing interest to reduce reliance on pesticides for disease control in viticulture and to focus on alternative methods, such as biocontrol agents. Several Trichoderma spp. strains are active against numerous plant pathogens, and their biocontrol activity is based on different mechanisms. In grapevine, T. harzianum T39 activates a plant-mediated resistance and reduces downy mildew symptoms, but its efficacy under abiotic stress conditions have not jet investigated. Our aim is to investigate the relationship between drought stress and P. viticola infection, and to characterize the efficacy of T. harzianum T39-induced resistance under water stress conditions