Mitochondrial genome in Hypsizygus marmoreus. Hypsizygus marmoreus

In this study, we are the first to report the complete sequence of the mitochondrial (mt) genome of the fungus, the circular genome-size of which is 102,752bp and contains 15 putative protein-coding genes, 2 ribosomal RNA subunits and 28 tRNAs. To explore the evolution of this mt genome, we compared the mtDNAs of the 27 fungal species in the Pezizomy cotina and Basidiomycotina subphyla, with the results revealing that H.marmoreusis a sister to T.matsutake（Tricholoma matsutake，Tricholoma）and the phylogenetic distribution of this fungusbased on the mt genome. Molecular clock analysis based on two fossil calibration points shows that ascomycetes and basidiomycetes diverged approximately 650 million years ago, indicating the robustness of the hypermetric tree. H.marmoreus and T. matsutake were estimated to have diverged 72.55 million years ago, and were the closest genetically among the 27 species. The analysis of molecular clocks and gene order showed that these fungus sequences are existence of a particularly high overall level of polymorphism and gene order varies significantly in the dikarya data set, indicatinga correlation between the gene order and the divergent time in the fungi mt genome. To detect the mt genome variations inH.marmoreus, we analyzed the mtDNAs sequences of 48 strains.The phylogeny and variation site type statistics of H.marmoreus provide clear-cut evidence for the existence of four well-defined cultivation isolated lineages, suggesting female ancestor origin of H.marmoreus. Fifteen conserved protein-coding genes of mtDNAs were analyzed, withfourteen revealed to be under purifying selection in the examined fungal species, and the remaining one, rps3, was under a value of dN/dS= 1.4 (7/5) ratio, suggesting the rapid evolution was caused by the positive selection on this gene.