Abstract
By next-generation sequencing analysis, 24 mating-type genes and mating-type-related genes were identified in the bipolar basidiomycete <i>Rhizopogon reseolus</i>, including two homeodomain protein genes, four pheromone receptor genes, and 18 genes around the A mating-type locus that are conserved among mushrooms.The 24 genes were clustered in three different nodes (assembled contig nucleotide sequences). Two pheromone receptor genes, Rcb1 and Rcb2, were closely linked with the Hox genes on node 8,230, and the distance between A2-Rcb1 and A2-hox2 was only 875 bp. The other two Rcb genes (A2-Rcb3 and A2-Rcb4) were located on node 11,781. Six genes that flanked the A mating-type locus and are conserved with other mushrooms were found in node 880. Linkage analysis using single-nucleotide polymorphism analysis revealed that the 24 genes located in the three nodes were genetically linked, and that the three nodes comprised a partial nucleotide sequence of a single chromosome. We hypothesized that the chromosome on which the A mating-type locus is located might have resulted from a recombination event between the A mating-type gene cluster and the pheromone and pheromone receptor cluster in ancient species of this bipolar mushroom.
