Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 15, 2003
Publication Date: August 15, 2003
Citation: CASTRILLO, L.A., VANDENBERG, J.D., GRIGGS, M. GENETIC RECOMBINATION BETWEEN VEGETATIVELY COMPATIBLE STRAINS OF BEAUVERIA BASSIANA IN A SUSCEPTIBLE INSECT HOST. PROCEEDINGS OF THE ANNUAL MEETING OF THE SOCIETY FOR INVERTEBRATE PATHOLOGY. 2003. v. 36. p. 48.
Gene exchange, along with mutation, could alter virulence or host range, and should be considered when assessing the risks of wide scale application of a mycoinsecticide. We assessed vegetative compatibility groups (VCG) among strains of B. bassiana representing indigenous strains from diverse insect hosts. Genetic similarity among strains was analyzed using random amplified polymorphic DNA markers. Our data revealed 24 VCGs among the 35 strains tested, with most of these groups comprised of only a single strain. We also observed a VCG comprised of nine genetically similar strains isolated from Colorado potato beetles (CPB) from the northeastern part of the US and from Quebec and Ontario, Canada. To determine the likelihood of recombination in the field, VCG studies in vitro were followed by co-inoculation studies of CPB larvae with complementary nit mutants of genetically distinguishable strains from the same or from different VCGs. Among the different nit pairings tested, heterokaryons were observed in two out of five same-VCG pairs, with only 5 to 15 % of the sporulating cadavers generating a few recombinants. In contrast, none of the infected beetles treated with non-compatible pairs generated recombinants. The large number of VCGs observed and the low frequency of in vivo recombination limited to vegetatively compatible strains indicate that this self/non-self recognition system may be an effective barrier preventing genetic exchange between dissimilar strains in the field.