High population diversity and increasing importance of the Eucalyptus stem canker pathogen, Teratosphaeria zuluensis, in South China

Coniothyrium stem canker, caused by Teratosphaeria zuluensis, is one of the most important diseases of plantation-grown Eucalyptus trees in tropical and sub-tropical areas of the world. Previous research on the population structure of T. zuluensis in China, Malawi and South Africa has suggested that T. zuluensis in these countries had independent origins, with the highest genetic diversity found in a population from South China. In this study, the genetic diversity of three T. zuluensis populations from different regions in South China was determined using ten microsatellite markers. Results showed that more than one genotype of T. zuluensis can occur on a single tree in all three populations and that a moderate to high genetic diversity exists within the populations. Population differentiation was evident between populations, and in one population there was evidence for a low level of genetic recombination. Comparisons among the three populations of T. zuluensis from South China suggest that they originated independently of each other.