Defining the role of the sugar transporter Sts1 in sexual development of the mushroom Schizophyllum commune

Abstract

Mushroom development in the fungus Schizophyllum commune is normally the result of a sexual interaction between two individuals differing at what are termed the A and B mating type loci. sts1 is a putative sugar transporter gene also implicated in the regulation of mushroom development. Null (Δ) mutant strains lacking functional copies of sts1 displayed severely attenuated mushroom production. When Δsts1 strains were outcrossed, some progeny displayed a “flat” phenotype, suggestive of an inappropriately‐activated B mating type pathway. Activation of this pathway normally requires the mating of two haploid individuals with different B mating type specificities. Specific B loci encode both a G‐protein coupled receptor (GPCR) and small lipopeptide pheromones that do not normally interact within self. We have investigated a possible link between the B mating type pathway and sts1 by outcrossing our Δsts1 strain with a compatible strain containing an incomplete B mating type locus. Only progeny with an intact B mating locus inherited from the sts1 parent were found to display a “flat” phenotype. This result suggests that the activation of the B pathway by Δsts1 is occurring at the level of the interaction between the GPCR and its “self” pheromones. Supported by a Union College IEF Grant to D.M.K.