Population genetic analyses suggest that the Eucalyptus fungal pathogen Ceratocystis fimbriata has been introduced into South Africa : research letter

Ceratocystis fimbriata is one of the most important pathogens of woody plants in the world. This fungus is also a serious pathogen of Eucalyptus species in various countries and has recently been reported from wounds on these trees in South Africa. Inoculation studies have shown that the fungus can cause disease on Eucalyptus spp. in South Africa, although trees dying in the field due to infection have never been encountered. The origin of C. fimbriata in South Africa is unknown, but there is some phylogenetic evidence that the fungus has a Latin American origin. In this study, microsatellite markers specifically designed for C. fimbriata were used to analyse the population diversity of 80 C. fimbriata isolates from Eucalyptus trees in South Africa. Analyses showed a low gene diversity (H = 0.36) and the population was found to be predominantly clonal (IA = 0.95, P ST = 0.99) and the maximum genotypic diversity was very low (1.23%). These data provide good evidence that C. fimbriata has been introduced into South Africa.