Ophiostoma tsotsi sp. nov., A Wound-infesting Fungus of Hardwood Trees in Africa
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Polymorphic sequence-characterised marker assays from a recent diversity study on the Ascomycete fungus Ophiostoma quercus reported that some isolates from Africa were genetically distinct from O. quercus. In the present study, these African isolates were compared with authentic O. quercus isolates by evaluating morphological characters, growth in culture, mating compatibility and DNA sequence data. The isolates from Africa were morphologically similar to O. quercus, presenting Pesotum and Sporothrix synanamorphs in culture. Phylogenetic analyses of the ribosomal internal transcribed spacer regions 1 and 2, β-tubulin and translation elongation factor 1-α gene regions confirmed that the African group represents a distinct species within the hardwood lineage of the O. piceae complex, closely related to O. ulmi and O. himal-ulmi. Mating studies between O. quercus and the African isolates showed that isolates mated predominantly with those of their own group, although there were rare cases of fertile crosses between the groups. Isolates residing in the African lineage are described here as a new species, O. tsotsi sp. nov.
KeywordsOphiostoma quercus Blue-stain fungi Pesotum Ophiostomatales
We thank Jolanda Roux, Ronald Heath and other colleagues who assisted with the collection of isolates. We acknowledge our African collaborators: Gerald Meke from the Forestry Research Institute of Malawi, Aza Mbaga from the Tanganyika Wattle Company, Tanzania, the Forestry Department and Makerere University, Uganda. We are also grateful to Dr. Seonju Marincowitz for assisting with light microscopy, Mr Alan Hall for assistance with scanning electron microscopy and Dr. Hugh Glen for providing the Latin diagnosis. Funding for this study was provided by the National Research Foundation (NRF), the Tree Protection Co-operative Programme (TPCP), the THRIP initiative of the Department of Trade and Industry (DTI) and the Department of Science and Technology (DST)/NRF Centre of Excellence in Tree Health Biotechnology, South Africa.
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