The location and analysis of two heterokaryon incompatibility (het) loci in strains of Aspergillus nidulans.

The heterokaryon incompatibility system in Aspergillus nidulans has been investigated by parasexual methods. The use of complementary auxotrophs with a repeated serial transfer method or with a protoplast fusion technique has enabled heterokaryons and diploid strains to be recovered from heterokaryon incompatible combinations of strains. The effects of allelic interaction at heterokaryon incompatibility (het) loci on the morphologies of the heterokaryon and diploid colonies isolated are described. Parasexual analyses conducted among strains belonging to the heterokaryon compatibility groups, h-cGl and h-cB, and the two recombinant compatibility classes, have located the hetA and hetB genes to linkage groups V and VI respectively.