ITS Polymorphism and Population Genomics Clarify the Relationship Between Group I and Group V in Lentinula edodes

Wild Lentinula edodes, also known as “Shiitake”, is distributed in many provinces of China, and southwestern China has the greatest genetic diversity of L. edodes germplasm resources. As determined by phylogenetic analyses of the internal transcribed spacer (ITS) of ribosomal RNA (rRNA), L. edodes was resolved into two non-sister lineages, known as Group I and Group V. In this study, the ITS fragments of 44 wild L. edodes strains, mainly from Yunnan Province of southwestern China, were cloned, sequenced, and analyzed. It was revealed that eight strains contained both Group I and Group V ITS. The protoplast monokaryotization strains (PMSs) and single-spore isolates (SSIs) were obtained from YAASM2342, whose mating types and ITS types were analyzed. The results confirmed that two heterokaryons of YAASM2342 contained Group I and Group V ITS, respectively. The strains of both Group I and Group V were present in the SSIs of each mating type at a ratio of ~1:1. Moreover, analyses of the population genomic dataset suggested that the recovered genetic groups could not correspond to Group I and Group V.