New insights into population structure of Beauveria bassiana with regard to vegetative compatibility groups and telomeric restriction fragment length polymorphisms

The occurrence of vegetative compatibility groups (VCGs) in Beauveria has been examined by analyzing compatible and incompatible reactions between complementary nitrate non-utilizing mutants. Complementary mutants (nia, and cnx) generated from 25 isolates from different host and insect origins were paired in all combinations revealing 14 different VCGs. Strains isolated from European corn borer in different European countries formed a distinct subspecific group whereas Sitona weevil isolates collected in the same country were found in different VCGs. A high level of polymorphism was detected by fingerprinting through Southern blot hybridization with a telomeric probe. Examination of DNA variations among isolates belonging to different VCGs suggested that variations in telomeric patterns was correlated with VCG groupings; these results underlined the existence of genetic limits to gene flow that would result in genetically diverse subpopulations.