Application of RAPD‐PCR for Virulence Type Analysis within Verticillium dahliae and V. longisporum

A collection of 24 isolates of Verticillium dahliae, 11 isolates of V. longisporum and one isolate of V. alboatrum originating from different host plants and geographical regions was tested for genetic variability by random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). Based on nine primers, the three Verticillium species could be clearly differentiated. Likewise, this analysis provided a distinct separation of vegetative compatibility groups (VCG) 2B, 4A and 4B of V. dahliae by specific DNA banding patterns. Additionally, V. longisporum was found to segregate into two subgroups with only 88% similarity. This molecular-genetic approach was used for the analysis of randomly selected Verticillium isolates from a field with high intensity of oilseed rape cultivation (33% in crop rotation). RAPD-PCR analysis revealed that 95 of 100 isolates tested belonged to V. longisporum and 5 to VCG 2B of V. dahliae. This 'study demonstrates an adaptation of Verticillium soil populations to a specific cropping history.