Terroir-associated variations in anthocyanin and proanthocyanidin accumulation in cabernet sauvignon berries: a...

Terroir is a complex system arising from the interplay of climate, soil, and microbial communities, and it influences the accumulation of anthocyanins and proanthocyanidins in grape berries-compounds that largely govern the color, structure, and sensory properties of red wines. The eastern foothills of Helan Mountain represent an emerging high-quality wine region in China, recognized for its distinctive wine typicity. However, the relationships between local terroir characteristics and the anthocyanin and proanthocyanidin profiles of Cabernet Sauvignon grapes remain poorly understood. In 2019, we selected 15 Cabernet Sauvignon vineyards across the five major sub-regions of this area, covering typical local management practices and soil types. We investigated the associations among climatic variables, soil physicochemical properties, soil microbial community structure, and the berry anthocyanin and proanthocyanidin composition. Distinct correlations were identified between various terroir factors and phenolic components. Total precipitation and the proportion of macroaggregates in soil mechanical aggregates were positively correlated with the contents of several monomeric anthocyanins, whereas soil sand content was negatively correlated with the total content of multiple phenolic compounds. Soil total phosphorus and nitrate nitrogen contents were positively associated with the levels of acylated malvidin-3-O-glucoside derivatives. Furthermore, specific soil microbial taxa-including the bacterial phyla Acidobacteria, Deinococcus-Thermus, Planctomycetes and Proteobacteria, and the fungal phyla Ascomycota and Basidiomycota-were closely linked to berry proanthocyanidin composition. These findings provide a valuable reference for precision viticulture management and the scientific delineation of sub-regions for Cabernet Sauvignon in the eastern foothills of Helan Mountain.