Trello, G. E. | bioRxiv Science

bioRxiv2026

Conserved Rhizosphere Microbiomes and Metabolic Functions Across Diverse Grapevine Rootstocks: Implications for Plant Elemental Composition

BackgroundWhile grapevine rootstocks are essential to commercial viticulture, researchers still lack a complete understanding of how these root systems and their associated microbiomes influence the vines mineral nutrition. Previous research has shown that rootstocks with similar pedigrees, reflecting the limited number of parental genotypes in the breeding pool, affect both the vines elemental profile and microbiome composition. Here, we extend this work by surveying a broader diversity of rootstock genotypes representing distinct parentage groups across multiple scions and by assessing both functional and taxonomic associations between the rhizosphere metagenome and vine elemental composition. ResultsWe used a rootstock diversity trial with ten rootstock genotypes grafted to one of two scions to simultaneously characterize the rhizosphere metagenome and elemental composition of both berries and roots. We found that elemental composition varied strongly among vine compartments, while scion and rootstock had comparatively minor effects. Berries of Cabernet Sauvignon contained higher concentrations of boron, potassium, and phosphorus than those of Chardonnay. Only three elements in root tissues differed among rootstock genotypes, and these differences were unrelated to genetic relatedness among rootstocks. Rhizosphere microbiome composition was also conserved across rootstocks, suggesting that diverse genotypes recruit a consistent microbial community with similar functional potential. By linking rhizosphere microbiome profiles with root elemental composition, we found that Streptomyces and Mesorhizobium were significantly associated with elemental patterns, showing negative correlations with a principal component heavily loaded for molybdenum, cadmium, potassium, and iron. ConclusionsOur findings suggest that vine compartment exerts a dominant influence on elemental composition, while rootstock genotypes have comparatively modest effects. Despite the overall conservation of the rhizosphere microbiome, specific microbial taxa were linked to elemental variation, highlighting potential microbe-element associations that may influence nutrient dynamics in the grapevine rhizosphere. These results provide a foundation for disentangling how root-associated microbes contribute to vine mineral nutrition, or vice versa, across diverse rootstock genotypes.

plant biology↗

bioRxiv2023

Grapevine bacterial communities across the Central Valley of California

Plant organs (compartments) host distinct microbiota which shift in response to variation in both development and climate. Grapevines are woody perennial crops that are clonally propagated and cultivated across vast geographic areas, and as such, their microbial communities may also reflect site-specific influences. These site-specific influences, and the microbial differences across site compose terroir, the environmental influence on wine produced in a given region. Commercial grapevines are typically composed of a genetically distinct root (rootstock) grafted to a shoot system (scion) which adds an additional layer of complexity. In order to understand spatial and temporal patterns of bacterial diversity in grafted grapevines, we used 16S rRNA metabarcoding to quantify soil and compartment microbiota (berries, leaves, and roots) for grafted grapevines in commercial vineyards across three counties in the Central Valley of California over two successive growing seasons. Community composition revealed compartment-specific dynamics. Roots assembled site-specific bacterial communities that reflect rootstock genotype and environment influences, whereas bacterial communities of leaves and berries displayed associations with time. These results provide further evidence of a microbial terroir within the grapevine root systems but also reveal that the microbiota of above-ground compartments are only weakly associated with the local microbiome in the Central Valley of California.

plant biology↗