Cultivar Contributes to the Beneficial Effects of PTA-271 and SC1 to Protect Grapevine Against .

Grapevine trunk diseases (GTDs) are a big threat for global viticulture. Without effective chemicals, biocontrol strategies are developed as alternatives to better cope with environmental concerns. A combination of biological control agents (BCAs) could even improve sustainable disease management through complementary ways of protection. In this study, we evaluated the combination of () PTA-271 and () SC1 for the protection of Chardonnay and Tempranillo rootlings against Bt67, an aggressive pathogen associated to Botryosphaeria dieback (BD). Indirect benefits offered by each BCA and their combination were then characterized , as well as their direct benefits . Results provide evidence that (1) the cultivar contributes to the beneficial effects of PTA-271 and SC1 against , and that (2) the BCA mutual antagonism switches to the strongest fungistatic effect toward -Bt67 in a three-way confrontation test. We also report for the first time the beneficial potential of a combination of BCA against -Bt67 especially in Tempranillo. Our findings highlight a common feature for both cultivars: salicylic acid (SA)-dependent defenses were strongly decreased in plants protected by the BCA, in contrast with symptomatic ones. We thus suggest that (1) the high basal expression of SA-dependent defenses in Tempranillo explains its highest susceptibility to , and that (2) the cultivar-specific responses to the beneficial PTA-271 and SC1 remain to be further investigated.