Homeodomain 1 Genes of the Different HD Subloci of Can Activate the HD Pathway and Are Involved in Mating, Clamp Cell Formation, and Upregulation of .

has two independent and functional mating type factors, HD and PR. The HD locus contains two separate subloci: HD-a and HD-b. In this study, we investigated the roles of genes of the HD-a and HD-b subloci in the process of mating, clamp cell formation, and regulation of ( gene) gene expression in . To this end, we introduced genes from mating compatible strains into monokaryon L11. Overexpression of gene of the HD-a sublocus resulted in the formation of pseudoclamps in L11 monokaryons. L11 mutants overexpressing the gene of the HD-b sublocus also similarly developed pseudoclamps in the L11 monokaryons. Moreover, these mutant L11 monokaryons produced complete clamps when crossed with monokaryotic strains that differed at the PR loci, i.e., when selective activation of the PR pathway was obtained through crossing. Thus, genes of the two different HD subloci in can activate the HD mating type pathway and induce clamp cell formation. In addition, activation of the HD pathway resulted in upregulation of the gene. Finally, to complete clamp cell formation, activation of the PR pathway appears to be essential. Overall, these findings were beneficial for deepening our understanding of sexual reproduction and fruiting body development of edible fungi.