Grapevine biochemical defense mechanisms under biotic stress: a focus on phenolic compounds accumulation and pathogen resistence

Climate change is profoundly reshaping viticultural landscapes by altering temperature patterns, precipitation, and increasing the frequency of extreme weather events. These shifts affect grapevine phenology, accelerate ripening, reduce fruit quality, and increase susceptibility to fungal pathogens, posing serious challenges to sustainable viticulture. While agronomic practices such as canopy management, rootstock selection, and predictive models offer partial mitigation, the grapevine’s physiological and biochemical responses—particularly the production of secondary metabolites—are essential for long-term adaptation. Among these, phenolic compounds, especially stilbenes, play a key role in inducible defense mechanisms. Stilbenes like resveratrol and ε-viniferin are synthesized in response to biotic stress, including infections caused by Plasmopara viticola, Botrytis cinerea, and wood-inhabiting fungi such as Phaeomoniella chlamydospora. These compounds accumulate in infected or surrounding tissues and exert antimicrobial activity by disrupting membranes and inhibiting microbial respiration. Stilbene biosynthesis is influenced by environmental conditions and varies across cultivars, as reflected in distinct gene expression patterns. Beyond their defensive function, phenolic compounds also contribute to fruit quality and offer potential health benefits, making their study relevant to both agriculture and nutrition. This thesis explores the intersection of climate stress, plant defense, and the metabolic plasticity of Vitis vinifera, highlighting stilbenes as key elements in grapevine resilience.