Diversity of endophytic fungi associated with branches of Berchemia discolor in the Limpopo Province of South Africa

Abstract

Previously, studies on Berchemia discolor trees focused on their pharmacological and nutritional properties. Despite the ecological, economical and pharmaceutical importance, little is known regarding the diseases affecting the species. One recently published paper dealing with fungi associated with B. discolor in Kenya reported 12 ascomycete species that cause dieback and cankers. Thus, the studies presented in this dissertation are the first that attempted to identify fungi associated with B. discolor in South Africa. A total of 29 species were tentatively identified from samples of B. discolor collected at different collection sites in the Limpopo Province of South Africa. These species were classified based on multi-gene DNA sequencing and the species belonged to the 17 genera within 10 families. out of the 29 species, eight species are potentially new to science. Botryosphaeriaceae species were the most notable and predominant in the natural ecosystems. Of the 29 species, 12 species overlapped on branches with dieback and asymptomatic branches, nine were isolated from branches with dieback, while 8 species were obtained from asymptomatic branches. No conclusive evidence could be found that the species obtained from the branches of B. discolor are the causal agents of the dieback disease, as Koch’s postulate was not applied in this study through pathogenicity trials. This study, however, should be seen as a foundational study as limited samples were collected from one province. The results from the chapters presented in this dissertation warrant further research in which the sampling areas and the number of sampled trees should be expanded in order to realise the full extent of the fungal species diversity on B. discolor and their potential impact on the health of these trees in South Africa.