Department of Plant and Soil Sciences
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Browsing Department of Plant and Soil Sciences by Author "Coetzee, M. P. A."
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Item Embargo Diversity and species overlap of Botryosphaeriaceae on some trees of Anacardiaceae in disturbed and undisturbed ecosystems in South Africa(2025-05-16) Ramabulana, Elelwani; Ogola, J. B. O.; Kunjeku, E.; Coetzee, M. P. A.; Slippers, B.The Botryosphaeriaceae are common and diverse on native and non-native plants. It has been established that the ability of Botryosphaeriaceae fungi to exist in healthy plant tissues as endophytes facilitates their global movement during the international trade of plants and plant products. It is important to understand whether fungi in the Botryosphaeriaceae have a restricted host range or a limited geographic distribution once introduced into new areas, and how ecosystem disturbances through human activities influence species diversity and distribution of fungi in the Botryosphaeriaceae. The current study explored Botryosphaeriaceae species diversity on native and non-native tree species of Anacardiaceae found in disturbed and undisturbed ecosystems, as well as species overlap of the Botryosphaeriaceae as endophytes and as pathogens in asymptomatic and symptomatic tissues of these trees. In addition, the genetic diversity and population structure of N. parvum, the dominant species occurring on asymptomatic mango fruit were assessed. These questions were addressed by sampling three tree species of Anacardiaceae, namely Sclerocarya birrea (marula), Mangifera indica (mango) and Lannea Schweinfurthii (false marula) in disturbed and undisturbed ecosystems in the Limpopo and Mpumalanga provinces, South Africa. The ecosystem disturbance study identified 11 species of Botryosphaeriaceae, namely Diplodia allocellula, Dothiorella brevicollis, Dothiorella dulcispinae, Dothiorella viticola, Lasiodiplodia crassispora, Lasiodiplodia exigua, Lasiodiplodia gonubiensis, Lasiodiplodia mahajangana, Neofusicoccum parvum, Oblongocollomyces ednahkunjekuae and Oblongocollomyces sp. 1 occurring on native and non-native Anacardiaceae in disturbed and undisturbed ecosystems. Ten of the 11 species were identified on trees in undisturbed ecosystems, while three were identified on trees in disturbed ecosystems. Lasiodiplodia crassispora and L. mahajangana were generalists on trees in disturbed and undisturbed ecosystems. The results from this study also indicated the ability of some species to cross-infect native and non-native Anacardiaceae growing next to each other. For example, N. parvum isolates occurred on both S. birrea (a native species) and M. indica (a non-native species) trees adjacent to each other in disturbed ecosystems. An investigation on species occurrence of the Botryosphaeriaceae as endophytes and as pathogens on the Anacardiaceae identified 12 species of Botryosphaeriaceae, D. allocellula, Dothiorella brevicollis, Do. dulcispinae, Do. viticola, Lasiodiplodia crassispora, L. exigua, L. gonubiensis, L. mahajangana, L. pseudotheobromae, Neofusicoccum parvum, Oblongocollomyces ednahkunjekuae and Oblongocollomyces sp. 1 in asymptomatic and symptomatic tissues. Dothiorella dulcispinae, L. exigua, L. gonubiensis, Oblongocollomyces ednahkunjekuae and Oblongocollomyces sp. 1 were exclusive to asymptomatic Anacardiaceae, while D. allocellula, Do. brevicollis, Do. viticola, L. crassispora, L. mahajangana and N. parvum occurred in asymptomatic and symptomatic Anacardiaceae indicating the ability to occupy healthy plant tissues as latent opportunistic pathogens on these trees. The N. parvum population genetics data was assessed based on nine microsatellite markers. This study indicated that the N. parvum population consists of three distinct genetic clusters characterized by high levels of genetic diversity. The three clusters were not correlated to host or geographic location indicating the lack of barrier on the movement of the fungus between the hosts and locations sampled. The study highlights the potential of mango fruit to serve as a source of international spread of Botryosphaeriaceae, especially of N. parvum.Item Open Access Diversity of fungi associated with dieback of Ziziphus Mucronata in Limpopo Province, South Africa(2020) Thaphathi, Polly; Kunjeku, E. C.; Ogola, J. B. O.; Coetzee, M. P. A.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.Item Open Access Survey of diseases on Marula (Sclerocarya birrea), in Tshikundamalema, Limpopo Province, South Africa(2016-05) Ramabulana, Elelwani; Kunjeku, E. C.; Roux, J.; Coetzee, M. P. A.; Coutinho, T. A.See the attached abstract below