Mutational analysis of natural alleles in and affecting the B incompatibility factor of Schizophyllum

Primary mutations in the alleles of alpha 1 and beta 7 of the B incompatibility factor of Schizophyllum were induced with X rays. An additional mutation unlinked to the B factor and affecting its regulatory function was detected. This mutation is effective in monokaryons with most B-factor specificities. The spectra of induced mutations in different alleles is discussed in reference to a polarity in the expression of the recognition function and the regulatory function by each locus of the B incompatibility factor.