Exploring the evolution of microbial communities from the phyllosphere and carposphere to the grape must of Vitis vinifera L. cv's Chardonnay and Pinot noir

Microbial communities associated with the grapevine phyllosphere and carposhere are a fundamental determinant of grape and wine quality. High throughput amplicon sequencing was used to profile the fungal and bacterial communities on the associated phylloplane and carposphere of Vitis vinifera L. cv's Chardonnay and Pinot noir in the Elgin and Hemel-en-Aarde wine districts of South Africa in the 2021-2022 growing season. The subsequent grape must was analysed to determine the prevalent microbiome. The most abundant bacterial and fungal genera found in both the phylloplane and carposphere of Chardonnay and Pinot noir were Pseudomonas and Filobasidium. The LEfSe (Linear discriminant analysis Effect Size) revealed significant differences in fungal and bacterial biomarkers from leaf, berry and grape must samples; however, no biomarkers were identified for cultivar nor location. Fungal β-diversity was significantly similar at different phenological stages, whereas bacterial β-diversity was significantly similar regardless of the site of colonisation. However, skin integrity of the grapes was may have influenced the microbial diversity.