Melosis as a source of spontaneous mutations in Schizophyllum commune.

Spontaneous mutation frequencies were determined for two loci in the fungus Schizophyllum commune, at meiosis and at mitosis. For both loci the meiotic frequency is significantly higher than the mitotic frequency. No correlation was found between meiotic mutagenesis and recombination of markers bracketing the mutant site. The meiotic temperature affected the spontaneous mutation frequency but not the recombination frequency in the cross examined. A number of suppressor mutations were detected for both loci examined. Almost all the suppressors are closely linked to the site they suppress. The distribution of mutations among the suppressor sites was different at meiosis and at mitosis.