Localization of auxotrophic and benomyl resistance markers through the parasexual cycle in the beauveria bassiana (Bals.) vuill entomopathogen

Abstract

Genetic studies to localize auxotrophic markers and resistance to benomyl fungicide and to analyze gene transfer on the Beauveria bassiana deuteromycete were carried out using the parasexual cycle. Parasexual crosses among strains with complementary genetic markers resulted in vigorous heterocaryons. Selection of the segregant products was made using two methodologies: total isolation and parental elimination. Colonies with recombinant traits were recovered directly from the heterocaryon in all crosses, and no diploid colony was isolated. This shows the high instability of the diploid nucleus in this species. Among the parasexual segregant products preferential recovery of markers in one of the parental strains involved in the crosses was detected, probably because of an inhibition of conidiogenesis from one parental strain to another. Genetic markers were localized in four linkage groups by the parasexual crosses. In the first group markers nic4, nic3, thi2, bio3, ade2, ths2, and ben1R were localized; in the second, the marker met1; in the third, pab1; and in the fourth, bio1. The parental strain 196/A11/3 is a carrier of translocation among the linkage groups I and III.