Misconception of Schizophyllum commune strain 20R-7-F01 origin from subseafloor sediments over 20 million years old.

Hole C0020A during Ocean Drilling Expedition 337 is the deepest hole in scientific ocean drilling (depth of 2466 m below the seafloor). The presence of microbial and fungal communities serves as firm evidence for life within sediments. The isolated from the core and cultivable in the laboratory strain S. commune 20R-7-F01, which has existed in a deep subseafloor environment for over 20 million years, is being considered a high-quality genome model for studying its evolution and environmental adaptation mechanism. We questioned the origin of the strain from the sediments using high mutagenic simple sequence repeats of DNA. The full genome analysis of mono-, di-, tri-, and tetra-motifs of DNA revealed no regularities in the quantitative distribution of motifs in different S. commune genomes. At of common trinucleotide motifs loci, strain 20R-7-F01 has the highest percentage of similarity (48.8%) among East Asian strains, which indicates an intensive genetic exchange. According to a multidimensional scaling of 1938 common simple sequence repeats of DNA loci, no signs were found that would indicate the spatial and temporal isolation of the 20R-7-F01 strain. The extreme insufficient of water, and oxygen, high temperature and pressure at the level of 2 km below the ocean floor, and the tetrapolar mating system make it impossible growth of mycelium with different nuclear status and formation of basidiocarps. The general obtained data confirm the terrestrial origin of S. commune strain 20R-7-F01 and the territory of the Far East of the Russian Federation (approximately Khabarovsk, Primorsky Krai) is the probable place of origin.