RESUMO
The composition, diversity and dynamics of microbial communities associated with grapevines may be influenced by various environmental factors, including terroir, vintage, and season. Among these factors, terroir stands out as a unique possible determinant of the pathobiome, the community of plant-associated pathogens. This study employed high-throughput molecular techniques, including metabarcoding and network analysis, to investigate the compositional dynamics of grapevine fungal pathobiome across three microhabitats (soil, woody tissue, and bark) using the Furmint cultivar. Samples were collected during late winter and late summer in 2020 and 2021, across three distinct terroirs in Hungary's Tokaj wine region. Of the 123 plant pathogenic genera found, Diplodia, Phaeomoniella, and Fusarium displayed the highest richness in bark, wood, and soil, respectively. Both richness and abundance exhibited significant disparities across microhabitats, with plant pathogenic fungi known to cause grapevine trunk diseases (GTDs) demonstrating highest richness and abundance in wood and bark samples, and non-GTD pathogens prevailed soil. Abundance and richness, however, followed distinct patterns Terroir accounted for a substantial portion of the variance in fungal community composition, ranging from 14.46 to 24.67%. Season and vintage also contributed to the variation, explaining 1.84 to 2.98% and 3.67 to 6.39% of the variance, respectively. Notably, significant compositional differences in fungi between healthy and diseased grapevines were only identified in wood and bark samples. Cooccurrence networks analysis, using both unweighted and weighted metrics, revealed intricate relationships among pathogenic fungal genera. This involved mostly positive associations, potentially suggesting synergism, and a few negative relationships, potentially suggesting antagonistic interactions. In essence, the observed differences among terroirs may stem from environmental filtering due to varied edaphic and mesoclimatic conditions. Temporal weather and vine management practices could explain seasonal and vintage fungal dynamics. This study provides insights into the compositional dynamics of grapevine fungal pathobiome across different microhabitats, terroirs, seasons, and health statuses. The findings emphasize the importance of considering network-based approaches in studying microbial communities and have implications for developing improved viticultural plant health strategies.
RESUMO
Improving our knowledge on biotic and abiotic factors that influence the composition of the grapevine mycobiome is of great agricultural significance, due to potential effects on plant health, productivity, and wine characteristics. Here, we assessed the influence of scion cultivar on the diversity and composition of fungal communities in the berries and leaves of three different cultivars. We generated DNA metabarcoding data, and statistically compared the richness, relative abundance, and composition of several functional groups of fungi among cultivars, which are partly explained by measured differences in chemical composition of leaves and berries and physiological traits of leaves. Fungal communities in leaves and berries show contrasting patterns among cultivars. The richness and relative abundance of fungal functional groups statistically differ among berry and leaf samples, but less so among cultivars. Community composition of the dominant functional groups of fungi, i.e., plant pathogens in leaves and saprotrophs in berries, differs significantly among cultivars. We also detect cultivar-level differences in the macro- and microelement content of the leaves, and in acidity and sugar concentration of berries. Our findings suggest that there appears to be a relatively diverse set of fungi that make up the grapevine mycobiome at the sampled terroir that spans several cultivars, and that both berry and leaf mycobiomes are likely influenced by the chemical characteristics of berries and leaves, e.g., pH and the availability of nutrients and simple carbohydrates. Finally, the correlation between fungal community composition and physiological variables in leaves is noteworthy, and merits further research to explore causality. Our findings offer novel insights into the microbial dynamics of grapevine considering plant chemistry and physiology, with implications for viticulture.
