Mitochondrial genome characteristics and evolution of Ganoderma fungi

【Objective】 To analyze mitochondrial genome characteristics and evolution of Ganoderma fungi, so as to provide theoretical references for species classification, molecular evolution and phylogenetic analysis of Ganoderma species.【Method】 Based on 15 mitochondrial genome sequences of Ganoderma fungi, mitochondrial genome characteristics, sequence polymorphism, simple repeat sequence(SSR), gene evolution and phylogeny were analyzed by bioinformatics software such as MEGA X, MISA, mVISTA, MAFFT, DnaSP, PAML X and IQ-TREE.【Result】The mitochondrial genomes of Ganoderma fungi were from 50603 bp to 124588 bp, with GC content of 25.4% to 27.3%, 15 conserved protein coding genes(PCG), 2 rRNA genes and 25-29 tRNA genes. SSR was mainly composed of AT base, and the proportion of mononucleotide repeat was the highest, followed by trinucleotide and tetranucleotide repeats. The mitogenome sequences of Ganoderma fungi varied greatly. The nucleotide diversity of non-coding region was higher than that of coding region, and the variation of coding sequence of nad6, nad3 and cob genes was higher. Intron length and mitogenome size were significantly positively correlated. The 15 conservative mitochondrial protein coding genes were mainly affected by purification selection, and cob, cox1 and nad2 genes contained positive selection sites. Gene coding preferred codons with A/T base, and of the 27 high-frequency codons, 13 ended with A and 14 ended with T. The phylogenetic analysis showed that Ganoderma fungi were mainly divided into two groups. Among them, G. sinense, G. boninense and G. wiiroense formed one group. And in the other group, G. calidophilum, G. leucocontextum and G. tsugae gathered together, forming sister groups with G. applanatum, G. meredithae, G. sichuanense and G. lucidum, and they formed a growp together【Conclusion】 Mitochondrial genomes have obvious genetic variation in evolution. The mitogenome length is mainly related to intron insertion or deletion, and a strong codon bias exists in protein coding genes.