Yeasts in Vineyard Soils: Diversity, Functional Potential and Links to the Grapevine and Wine

This review analyses the diversity and ecology of yeast communities in vineyard soils and the grapevine rhizosphere, evaluates the evidence linking them to grape- and must-associated yeasts, and outlines their functional potential within viticultural agroecosystems. Amplicon-sequencing studies show that basidiomycetous yeasts predominate in vineyard soils, whereas culture-based data indicate that ascomycetous yeasts such as Torulaspora delbrueckii can also be abundant around harvest. Vineyard soil is an important reservoir and a potential source of some grape-associated yeasts, such as T. delbrueckii and Lachancea waltii, but current evidence does not support it as the main source of the dominant yeasts of spontaneous fermentation, and exchanges between soil and grapes appear to be bidirectional. Plant growth promotion, soil aggregation through extracellular polymeric substances, bioremediation of heavy metals and pesticides, and biocontrol of phytopathogens have been reported for yeast species that also occur in vineyards, but mostly for isolates from other habitats and often only in vitro; these functions therefore remain hypotheses for vineyard soil yeasts. Management practices, including tillage, cover crops and copper-based plant protection, shape soil fungal communities, although their specific effects on yeasts are poorly known. Native vineyard soil yeasts selected according to biosafety criteria may represent candidate bioinoculants for sustainable viticulture, a hypothesis that requires testing on grapevine under field conditions.