Isolation of the B alpha and B beta mating-type loci of Schizophyllum commune.

The B mating type of the basidiomycete fungus, Schizophyllum commune is determined by two, tightly linked, multi-specificity (also called multi-allelic) loci: B alpha and B beta. A plasmid library was used in DNA-mediated transformation to obtain transformants that displayed B-directed development. Plasmids that conferred B alpha 1 and B beta 1 mating-type specificities were rescued from the transformants. Fragments of DNA from each plasmid hybridized to genomic DNA from the strain used to make the plasmid library; however, they did not hybridize, or hybridized only weakly, to genomic DNA from strains with mating-type specificities different from B alpha 1 or B beta 1. The cloned fragments are presumed to correspond to active regions of each B mating-type locus.