Isolates of Colletotrichum gloeosporioides (Teleomorph: Glomerella cingulata) with different host specificities mate on northern jointvetch

Two isolates of Colletotrichum gloeosporioides (teleomorph: Glomerella cingulata) with different host specificities (one isolate from the leguminous weed northern jointvetch and the other from pecan) that mate on agar media were tested for their ability to cross on northern jointvetch (Aeschynomene virginica). Stems of living northern jointvetch plants were inoculated with one of the isolates and, after 1 week, the same sites were inoculated with the other isolate. Inoculated stem pieces were excised, incubated on modified Czapek-Dox agar or moistened sterile filter paper, and monitored for the formation of perithecia with ascospores. Ascospore progeny from crosses on northern jointvetch plants and on agar medium were isolated and compared. Nuclear and mitochondrial DNA RFLP markers were used to confirm that outcrossing had occurred in both sets of crosses. In addition, progeny were analyzed for pathogenicity to northern jointvetch and apple (G. cingulata causes both pecan anthracnose and bitter-rot of apple). None of the progeny were pathogenic to northern jointvetch, but they exhibited varying degrees of pathogenicity to apple fruits. These results indicate that isolates of C. gloeosporioides with different host specificities may be capable of outcrossing on a parental host producing viable, sexually recombinant progeny. (C) 1996 Academic Press, Inc.