Lentinula edodes shows atypical mating behaviors deviated from tetrapolar mating in outcrossing. To better understand the mating behavior, we investigated variations in the mating type genes, residing in A and B mating loci, of 129 dikaryotic strains from East Asia. Through sequence analysis of A locus, we found that hypervariable region spanning N-term of HD2-intergenic region-N-term of HD1 could represent A mating type of L. edodes. Mating and hypervariable region analyses revealed 50 unique A mating types: 27 from 98 cultivated strains, 33 from 31 wild strains, and 10 commonly found. It was also revealed that only a few A mating type alleles such as A1, A4, A5, and A7 were prevalent in cultivated strains. The A mating type in wild strains were highly diverse: 23 unique A alleles were discovered in small mountainous area in Korean peninsula. The B locus was assessed by allelic variations in pheromone (PHB) and pheromone receptor (RCB) pairs. Sequence analyses revealed 5 alleles of RCB1 with 9 associated PHBs in B sublocus and 3 alleles of RCB2 with 5 associated PHBs in B sublocus. Each RCB was primarily associated with two PHBs. This allowed us to propose 15 B mating types via combinations of five B and three B subloci. Thus, the total number of mating types in L. edodes became 750 through a combination of 50 A and 15 B. This number will further increase because of rapid diversification of A mating type and possible emergence of variants of RCBs and PHB-RCB combinations.

• Byeongsuk Ha(Division of Life Science, Gyeongsang National University)
• Hyeon-Su Ro(Division of Life Science, Gyeongsang National University)