Microbial inoculation shapes local and systemic grapevine microbiota and wine metabolites across ages and managements

Given the established role of soil microbiomes in shaping plant traits, we hypothesized that alterations in rhizosphere microbial communities would impact grape berry microbiota and wine metabolite profiles along a controlled production chain. In this study, we investigated how a soil-applied bioinoculum influences root- and grape berry-associated prokaryotic and fungal communities and the chemical composition of wine. In a field study, a commercial bioinoculum was applied to grapevines in two vineyards located in the same site but differing in age and management practices. Over two growing seasons, we characterized bulk soil, rhizosphere, root, and grape berry microbiomes, analyzed the leaf ionome and the chemical composition of the resulting must and wines. Our results revealed that bioinoculum shaped the fungal community with a limited impact on the prokaryotic community and led to an increased abundance of plant growth-promoting microbes in the root endosphere. Integrated bioinformatic analyses revealed that bioinoculum treatment systemically altered berry- associated microbial communities, with downstream effects on must and wine metabolic composition. Notably, wines from treated plants exhibited higher acidity and polyphenol content. These results highlight that belowground microbiomes influence grape and wine metabolite profiles and underscore the potential of microbial inoculants to modulate wine quality.