Vineyard mycobiota shows a local and long-term response to the organic mulches application

Viticulture faces global warming challenge, prompting focus on sustainable practices. Organic mulches, an alternative to conventional practices, have shown the potential to enhance plant performance and soil quality. However, their impact on soil and must microbiota remains unexplored. Our three-year study, conducted in two vineyards located in Logrono and Aldeanueva within the appellation of origin (DOCa) Rioja (Spain) aimed to assess the effects of five soil treatments-two conventional (Herbicide (H) and Tillage (T)) and three organic mulches (Grapevine Pruning Debris (GPD), Spent Mushrooms Compost (SMC) and Straw (S))- on soil and must fungal communities through a metataxonomic approach (ITS region). We hypothesized that mulches might modify soil and must fungal microbiota, thus influencing plant health and the winemaking process. Our findings revealed that soil and must fungal communities were primarily driven by location. While treatments did not significantly impact must microbiota, soil fungal communities varied with treatments in the third year, with notable disparities across locations. In Logrono, GPD and H showed the highest diversity, while S exhibited the highest diversity in Aldeanueva. Besides, none of the mulches promoted the growth of pathogenic fungi associated with common vineyard diseases. Finally, the Saccharomycetaceae family was found in must and soil, indicating its presence in the soil prior to grape colonization. Overall, location emerged as the primary factor influencing soil and must fungi. Organic mulches demonstrated long-term effects on soil fungal diversity, although these effects varied across locations. This study pioneers a comprehensive assessment of organic mulches in shaping vineyard fungal communities across diverse soils, offering unprecedented insights into sustainable practices that enhance soil biodiversity and ecosystem resilience without elevating disease risk.