VIEW ARTICLE

Sexual Incompatibility and Aspects of the Mono- and Dikaryotic Phases of Typhula idahoensis. Barry M. Cunfer, Experimental Aide, Department of Plant Pathology, Washington State University, Pullman 99163, Present address: Department of Plant Pathology, Montana State University, Bozeman 59715; Phytopathology 64:123-127. Accepted for publication 3 July 1973. DOI: 10.1094/Phyto-64-123.

Typhula idahoensis has tetrapolar incompatibility with multiple alleles. Seven A and six B incompatibility alleles were recovered from six field collections. Several alleles at both loci were common to more than one collection. Tetrapolar incompatibility with six alleles at each locus was found in three field collections of T. incarnata, confirming previous results with this species. Interspecies matings were noncompatible in every case, supporting the established species designations. At least 99% of the basidiospores are uninucleate when ejected from the basidium, but subsequent mitotic divisions may occur prior to germination. Monokaryotic isolates and incompatible pairings of monokaryons either produce no sporophores or produce sterile sporophores, whereas field-collected dikaryotic isolates and compatible matings of monokaryons produce fertile sporophores. As a group, dikaryons grew faster in vitro than monokaryons, but there was much variability in growth rate among isolates of both genetic conditions. Optimum growth of mono- and dikaryons was at 10 and 15 C. There was no correlation between mycelial growth rate and virulence to wheat among monokaryons but virulence increased with increase of growth rate among dikaryons. The importance of the results to pathogenicity of the basidial stage on cereals is discussed.