Diversity of fungi associated with dieback of Ziziphus Mucronata in Limpopo Province, South Africa

Abstract

Ziziphus mucronata (buffalo thorn, Rhamnaceae) is an indigenous tree that serves multipurposes to rural communities and wildlife across Africa. The tree is considered important because of its useful parts for various purposes. For example, leaves of this tree can be consumed as a vegetable by humans and wild animals such as antelopes and baboons feed on them. Fruits from Z. mucronata are edible and nutritious to both human and wild animals such as monkeys. Roots from this tree are used for medicinal purposes by people living in rural areas for treatment of wounds, snake bites, swelling glands as well as diarrhoea. However, the tree face diseases such as dieback that negatively affect its production and there is little research on diseases of Z. mucronata in South Africa. This study was conducted in Limpopo Province, in three different sites namely Tshikundamalema, Buzzard Mountain Farm and Wits Rural Facility to identify fungi from branches of Z. mucronata showing dieback symptoms. Symptomatic branches were collected from each site and processed in the laboratory before primary isolations. Isolates obtained from the samples collected were identified based on their morphology where isolates were grouped according to their morphological characteristics such as colour and structure of mycelia. The isolates were further identified based on DNA sequence data from multiple genome regions including the internal transcribed spacer (ITS), beta-tubulin (BT) and the translation elongation factor (TEF) genomic regions and phylogenetic analyses. Fungi identified in this study were from families Botryosphaeriaceae, Diaporthaceae, Cytosporaceae (=Valsaceae), Nectriaceae, Pleosporaceae and Didymellaceae. Fungi identified include Dothiorella (=Spencermartinsia), Diplodia, Botryosphaeria, Neofusicoccum, Fusarium, Diaporthe (=Phomopsis), Cytospora, Didymella (=Phoma) and Alternaria. Results obtained from this study showed the diversity of fungi associated with dieback of Z. mucronata in Limpopo Province. Studies in other parts of Limpopo Province are needed to further investigate the diversity of fungi found on branches of Z. mucronata with dieback.