The mating-type locus Bα1 of Schizophyllum commune contains a pheromone receptor gene and putative pheromone genes

Analysis of the multispecific Bα mating-type locus of Schizophyllum commune provided evidence that pheromones and pheromone receptors govern recognition of self versus non-self and sexual development in this homobasidiomycetous fungus. Four subclones of an 8.2 kb genomic fragment carrying Bα1 specificity induced B-regulated sexual morphogenesis when introduced into a strain with one of the eight compatible Bα specificities that are known to exist in nature. One of these clones, which activated all other Bα specificities, contains a gene termed bar1. The predicted protein product of bar1, as well as that of bar2, a homologous gene isolated from a Bα2 strain, has significant homology to known fungal pheromone receptor proteins in the rhodopsin-like superfamily of G protein-linked receptors. The other three active Bα1 clones were subcloned further to identify the minimal active element in each clone. Every active subclone contains a putative pheromone gene ending in a signal for possible isoprenylation. A message of ~600 bp was observed for one of these genes, bap1(1). This paper presents the first evidence for a system of multiple pheromones and pheromone receptors as a basis for multispecific mating types in a fungus.