Global movement and population biology of Mycosphaerella nubilosa infecting leaves of cold-tolerant Eucalyptus globulus and E. nitens

Using 10 polymorphic DNA-based microsatellite markers, the genetic diversity of eight Mycosphaerella nubilosa populations from Eucalyptus, comprising 497 isolates from five different countries, was studies using a hierarchical sampling regime. Mycosphaerella nubilosa from eastern Australia (New South Wales) had higher gene (0·506) and genotypic (76%) diversity than other populations, supporting the view that this represents the origin of the pathogen. It was also evident that M. nubilosa populations from Europe and Tanzania were clonal, with the same multilocus haplotypes occurring in South Africa, but being absent in Australia. This suggests that M. nubilosa may have been introduced into Europe via Africa, with a pathway of gene flow from Australia to South Africa, further into Africa and finally to Europe.