Visagie, Cobus2023-07-102023-07-102023-092023*S2023http://hdl.handle.net/2263/91324Dissertation (MSc (Microbiology))--University of Pretoria, 2023.Soybeans (Glycine max) are a significant source of oil and protein and a growing component of Africa’s agricultural economy. Knowledge of fungal diversity, including those that can cause soybean diseases, is to some degree documented worldwide but is lacking in South Africa. Fungal and mycotoxin surveys are essential for ensuring safe food and feed in South Africa, but very few have studied this for South African soybeans. The first chapter of the dissertation provides a literature overview of the fungal and oomycete diseases that affect soybeans. The chapter emphasizes the significance of soybeans in the global economy and highlights the crucial role of soybeans as a source of essential nutrients for both humans and animals. Moreover, the chapter elucidates the different mycotoxins that are commonly associated with soybean seeds and soy meal. In addition, the chapter provides a detailed summary of each disease, outlining the characteristic in-field symptoms, causal agents, and techniques used for identifying the species based on both morphological and molecular data. The second chapter aimed to identify fungal diversity and mycotoxins associated with pre-stored soybean seeds in South Africa. This study resulted in 411 fungal strains recovered that were identified as 24 genera and 81 species. The dominant genera isolated were Aspergillus, Cladosporium, Penicillium, Fusarium, Alternaria Didymella, and Talaromyces. No mycotoxins were detected in any of the samples analysed, even though several mycotoxigenic species like A. flavus, A. parasiticus, A. westerdijkiae, F. boothii, and F. verticillioides were isolated. This survey is the first to determine the mycotoxin levels and fungal species present in soybeans and it thus provides important baseline knowledge for an increasingly important oilseed crop. The third chapter aimed to identify the fungal diversity associated with symptomatic soybean leaves, roots, stems, and seeds in South Africa. This study resulted in 200 fungal strains representing 22 genera and 38 species. Important genera and the number of strains isolated during this study are Sclerotinia, Epicoccum, Alternaria, Fusarium, Diaporthe, and Macrophomina, respectively. Certain species identified from these genera have been previously reported as the causal agents of soybean diseases alternaria leaf spot (caused by Alternaria alternata), charcoal rot (caused by Macrophomina phaseolina), sclerotinia stem rot (caused by Sclerotinia sclerotiorum), and phomopsis seed decay (mainly caused by Diaporthe longicolla). There are limited studies on fungal diversity associated with soybeans in South Africa. Koch's postulates are required to determine if these species can cause soybean diseases in South Africa. The results of this study provide information on fungal diversity and show which fungi may potentially pose a threat to South African soybeans This study provides important knowledge on fungal diversity associated with South African soybeans which are currently very limited. Previous international fungal diversity studies have used the ITS barcode or morphology to identify fungal species. The aim of this study was to identify fungal species using morphology and molecular sequencing. DNA sequences were generated based on markers that accurately identify and distinguish between closely related species. This study has generated important baseline knowledge on fungal diversity in South Africa. The DNA sequences generated during this study were deposited to Genbank with accession numbers available to aid future fungal identifications. Strains have been preserved in culture collection and are readily available for future studies such as novel secondary metabolite analysis, in vitro mycotoxin production, or Koch’s postulates to determine causal agents of soybean diseases in South Africa. This project provides baseline knowledge and contributes to the aim of safe food and feed in South Africa.en© 2023 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.South AfricaSoybeansFungal diversityMycotoxinsFood securityUCTDDissertationu1600608010.25403/UPresearchdata.23617839