Year, Location, and Variety Impact on Grape-Associated Mycobiota of Arkansas-Grown Wine Grapes for Wine Production.

Wine grape berries (Vitis spp.) harbor a wide variety of yeasts and filamentous fungi that impact grapevine health and the winemaking process. Identification of these fungi could be important for controlling and improving wine production. The use of high-throughput sequencing (HTS) strategies has enabled identification and quantification of bacterial and fungal species in vineyards. The aims of this study were to identify mycobiota from Cabernet Sauvignon and Zinfandel (V. vinifera), Carlos and Noble muscadines (V. rotundifolia), Cynthiana (V. aestivalis), and Vignoles hybrid (cross of different Vitis spp.) grapes, and investigate the effect of grape variety, location, and year on grape fungal communities. Grape berries were collected in 2016 and 2017 from four vineyards located in Arkansas. The HTS of the Internal Transcribed Spacer 1 region was used to identify grape indigenous epiphytic and endophytic fungal communities. The predominant genera identified on the Arkansas wine grapes were Uwebraunia, Zymoseptoria, Papiliotrema, Meyerozyma, Filobasidium, and Curvibasidium. Overall, the data suggested that grape fungal community distribution and relative abundance were influenced by grape variety, year, and location, but each was influenced to a different extent. Not only were grape mycobiota influenced by year, variety, and location but also it appeared that communities from the previous year impacted microbial communities the following year. For example, an increase of the mycoparasite Ampelomyces quisqualis was noticed in 2017 on grapes that carried the causal agent of powdery mildew, Erysiphe necator, in 2016, thus, amplifying the importance of vineyard microbiota knowledge for disease management and winemaking.