Characterization of the capacity of yeast cell wall extracts to induce grapevine tolerance to drought and pathogens.

Viticulture is affected by several abiotic and biotic stresses causing huge yield losses and deterioration of berry quality. Due to climate change drought has become one of the major threats to grapevine production. Among biotic stresses, diseases caused by the oomycete Plasmopara viticola and the fungal pathogen Botrytis cinerea, causal agents of downy mildew and grey mold, respectively, are major concerns for grapevine. The management of these diseases mostly relies on chemical control with the application of copper-based products and/or synthetic fungicides that determine negative effects on the environment and on the health of vine growers and consumers. Therefore, the searching for sustainable alternatives to the use of chemical control is crucial. On this basis, we tested different cell wall extracts from the yeast Saccharomyces cerevisiae for the capacity to induce grapevine tolerance to water deficit and resistance to P. viticola and B. cinerea infection. One of the yeast extracts that proved effective in inducing tolerance to the pathogens was selected to evaluate its efficacy in promoting internode elongation rate and stomatal conductance under well watering and water deficiency conditions. Our results showed that the yeast extract applied to grapevine did not promote internode elongation but determined a positive impact on stomatal conductance after water deprivation during the recovery phase.