FUNGAL DIVERSITY AND DYNAMICS IN CHAMPAGNE VINEYARDS: FROM VINE TO WINE

Abstract

Champagne is a well-known wine region in Northern France with distinct terroirs and three main grape varieties. As for any vineyard, wine quality is highly linked to the microbiological characteristics of the raw materials. However, Champagne grape microbiota, especially its fungal component, has yet to be fully characterized. Our study focused on describing this mycobiota, from vine to small scale model wine, for the two main Champagne grape varieties, Pinot Noir and Meunier, using complementary cultural and omics approaches.

Changes in microbial diversity and dynamics, especially mycobiota colonizing grapes, was evaluated at 5 berry ripening and vinification stages in 31 vineyards for two harvests. Grapes were collected at fruit set, veraison and harvest and micro-pressing (40 kg) and micro-vinifications (5L) of grape musts from each vineyard were performed.

For both harvests, fungal counts increased during berry ripening (although lower counts were observed in 2022 versus 2021), remained relatively high in musts before yeasts solely dominated in laboratory wines. Clear shifts in mycobiota diversity were observed from vine to laboratory wine for both years. Berries were dominated by yeasts (including filamentous Aureobasidium spp.) regardless of ripening stage with an increase in mold diversity during ripening. Cladosporium (7 species identified) were predominant in unmature berries before other molds colonized grapes, especially Penicillium (9 species identified) and Botrytis cinerea, from veraison onwards. Metagenetic analyses (equivalent to 450 samples in 2021) were well correlated with culture-dependent data. This approach confirmed the predominance of yeasts (Aureobasidium and Vishniacozyma) at both fruit set and veraison, in addition to Cladosporium, although higher fungal diversity and variability between musts was observed.

This unprecedent and thorough description of mycobiota from unmature berries to microvinified wines will clearly contribute to a better understanding of the fungal determinants of specific traits linked to wine quality or defects. Microbial co-occurrence networks and global analyses with the generated climatic data and vineyard practices is currently being explored to understand species interactions and identify factors shaping mycobiota composition.