Characterization of fungal communities of developmental stages in table grape grown in the northern region of South Africa

Abstract

AIMS : To determine fungal communities that characterize table grapes during berry development. METHODS AND RESULTS : Two agro-ecologically different table grape commercial farms (site A and B) were used in this study. Samples were collected at full bloom, pea size and mature stages, from three positions (inside centre, eastern and western peripheral ends) per site. Total DNA extraction, Illumina sequencing and analysis of 18 pooled samples for fungal diversity targeting ITS1-2 generated a total of 2 035 933 high-quality sequences. The phylum Ascomycota (77.0%) and Basidiomycota (23.0%) were the most dominant, while the genera, Alternaria (33.1%) and Cladosporium (24.2%) were the overall dominant postharvest decay causing fungi throughout the developmental stages. Inside centre of site A were more diverse at full bloom (3.82) than those at the peripheral ends (<3.8), while at site B, the peripheral ends showed better diversity, particularly the eastern part at both full bloom (3.3) and pea size (3.7). CONCLUSION : Fungal population diversity varies with different phenological table grape growth stages and is further influenced by site and vine position within a specific vineyard. SIGNIFICANCE AND IMPACT OF THE STUDY : The information on fungal diversity and succession in table grapes during preharvest growth stages is critical in the development of a more targeted control strategy, to improve postharvest quality of table grapes.