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Fungal diversity of developmental stages in table grapes grown in South Africa

Lise Korsten: University of Pretoria

<div>Physiological changes in plant growth affect the diversity and adaptation of microbiota, including fungi. Hence the study aim was to determine fungal communities that characterise table grapes during berry development. The study was done at two agro-ecologically different table grape commercial farms (site A and B). Samples were collected at full bloom, pea size and mature berry 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 with an average length of 150 bp. Overall, the pea size stage (829 OTUs) had the richest microbial community, compared to full bloom (569 OTUs) and mature stages (491 OTUs) at all sites. The phylum <em>Ascomycota</em> (77.0%) and <em>Basidiomycota</em> (23.0%) were the most dominant, while the genera, <em>Alternaria</em> (33.1%) and <em>Cladosporium</em> (24.2%) were the overall dominant postharvest decay causing fungi throughout the developmental stages. Fungal population diversity varies with different phenological table grape growth stages and it is further influenced by site of production and the position of the vine within a specific vineyard. 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.</div>