The mating reaction in yeast. II. Spontaneous occurrence of omni-mating types.

Meiosis in diploids of Saccharomyces cerevisiae either homozygous or heterozygous for the dmt gene result, in about 5% of the meiotic products, in spores which have undergone an interconversion at the mating-type locus. Some of these interconversions appear to be the result in the generation of spontaneous omni-mating strains. This phenomenon has now been quantitated and the distribution of mating-type loci in these "natural" amni-mating types determined.