Population structure of Holocryphia capensis (cryphonectriaceae) from Metrosideros angustifolia and its pathogenicity to Eucalyptus species

Abstract

Holocryphia capensis is a recently described fungus that infects native Metrosideros angustifolia (Myrtaceae, Myrtales) trees in South Africa. This species is related to a number of serious canker pathogens of trees in the Cryphonectriaceae. An ability to produce lesions on M. angustifolia in artificial inoculation studies and its close relationship to the introduced eucalypt pathogen, H. eucalypti, raises concerns as to its diversity and possible impact on Myrtaceae in Southern Africa. Eight microsatellite markers were used to study the genetic diversity of H. capensis isolates from four sites in the Western Cape Province. All isolates could be assigned to one population, with very low gene and genotypic diversity. This was despite the fact that sexual structures of the fungus are found on infected trees. The results suggest that H. capensis could have been introduced into the Western Cape from a single, as yet unknown origin. Pathogenicity tests showed that H. capensis is pathogenic to the tested Eucalyptus clone.