A chromosome assay method for the detection of heterokaryon incompatibility (het) genes operating between members of different heterokaryon compatibility (h-c) groups in Aspergillus nidulans.

Protoplast fusion has made possible the isolation of a diploid strain from haploid parents belonging to heterokaryon compatibility (h-c) groups Q and Gl of Aspergillus nidulans. This diploid was not fully heterokaryon compatibility tests conducted between selected pairs of parasexually derived progeny strains facilitated a chromosome assay method for the detection of heterokaryon incompatibility (het) genes. Despite the lack of segregation for the linkage group VI marker, it proved possible to locate het genes on linkage groups III, V, VI and VII. Backcross data detected five het gene differences operating between the h-cQ and h-cGl parental strains. Two het loci were located on linkage group III.