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In the present study, we assembled the mitogenomes of Pleurotus citrinopileatus and Pleurotus platypus. The circular mitogenome of the two Pleurotus species comprises a set of 14 conserved protein-encoding genes (PEGs), 2 RNA genes (small subunit ribosomal RNA and large subunit ribosomal RNA), and 24 tRNAs, with sizes of 60,694 and 73,807 bp, respectively. They contain 4 and 10 introns with 3 and 10 intronic open reading frames (ORFs), respectively. Thirteen position classes (Pcls) of introns were found in the cox1 gene of four Pleurotus species. The number and class of Pcl varied among different Pleurotus species, indicating that numerous events of loss and gain occurred during evolution of Pleurotus. Comparative mitogenomic and collinearity analyses reveal that large-scale gene rearrangements may have occurred during the evolution of Pleurotus citrinopileatus and Pleurotus platypus, including gene rearrangements and inversions, which may be related to the observed high amounts of repetitive DNA elements (5.62 and 5.45%, respectively). Phylogenetic analysis based on concatenated mitochondrial protein sequences reveals that concatenated mitochondrial genes are suitable as molecular markers for phylogenetic analysis. This serves as the first report on large-scale rearrangements in the mitochondria of the genus Pleurotus, thereby improving our understanding of the evolution of the Pleurotus genus and other macrofungi.

The medicinal fungus Laetiporus sulphureus is widely distributed worldwide. To screen for molecular markers potentially useful for phylogenetic analyses of this species and related species, the mitochondrial genome of L. sulphureus was sequenced and assembled. The complete circular mitochondrial genome was 101,111 bp long, and contained 38 protein-coding genes (PCGs), 2 rRNA genes, and 25 tRNA genes. Our BLAST search aligned about 6.1 kb between the mitochondrial and nuclear genomes of L. sulphureus, indicative of possible gene transfer events. Both the GC and AT skews in the L. sulphureus mitogenome were negative, in contrast to the other seven Polyporales species tested. Of the 15 PCGs conserved across the seven species of Polyporales, the lengths of 11 were unique in the L. sulphureus mitogenome. The Ka/Ks of these 15 PCGs were all less than 1, indicating that PCGs were subject to purifying selection. Our phylogenetic analysis showed that three single genes (cox1, cob, and rnl) were potentially useful as molecular markers. This study is the first publication of a mitochondrial genome in the family Laetiporaceae, and will facilitate the study of population genetics and evolution in L. sulphureus and other species in this family.

In this present study, we assembled and analyzed the mitogenomes of two asymbiotic and six ectomycorrhizal Amanita species based on next-generation sequencing data. The size of the eight Amanita mitogenomes ranged from 37,341 to 137,428 bp, and we considered introns to be one of the main factors contributing to the size variation of Amanita. The introns of the cox1 gene experienced frequent gain/loss events in Amanita; and the intron position class cox1P386 was lost in the six ectomycorrhizal Amanita species. In addition, ectomycorrhizal Amanita species had more repetitive sequences and fewer intergenic sequences than asymbiotic Amanita species in their mitogenomes. Large-scale gene rearrangements were detected in the Amanita species we tested, including gene displacements and inversions. On the basis of the combined mitochondrial gene set, we reconstructed the phylogenetic relationships of 66 Basidiomycetes. The six ectomycorrhizal Amanita species were of single origin, and the two saprophytic Amanita species formed two distinct clades. This study is the first to elucidate the functions of the mitogenome in the evolution and ecological adaptation of Amanita species.