Sequence characteristics and phylogenetic relationship of the mitochondrial genome of Akanthomyces lecanii

Abstract:

[Background] Akanthomyces lecanii is an important entomogenous fungus for biocontrol, and its mitochondrial genome has not been reported. [Objective] The mitochondrial genome of A. lecanii was systematically studied, which would help clarify the taxonomic status of this fungus and provide a molecular basis for the phylogenetic research and the resource protection and utilization of Cordycipitaceae. [Methods] The full-length mitochondrial genome of A.lecanii RCEF6920 was sequenced, and bioinformatics tools were used to probe into the composition, sequence repeats, phylogenetic relationship, and collinearity. Furthermore, the mitochondrial genome was compared between A.lecanii and other species of Cordycipitaceae. [Results] The mitochondrial genome of A.lecanii RCEF6920 was a circular DNA molecule of 24 577 bp and contained 43 genes, including 15 protein-coding genes, 2 rRNA genes, and 26 tRNA genes. Only one intron was detected in the mitochondrial genome, and it interrupted rnl and contained orf447 encoding ribosomal protein S3. The nucleotide composition of the mitochondrial genome was A+T biased (72.89%). The 26 tRNA genes could transfer all the 20 amino acids and presented a typical cloverleaf structure. AGA was the most frequently used codon of the protein-coding genes. Arginine and leucine were identified as the most common amino acids, while methionine and tryptophan were the least common amino acids in the protein-coding genes. The phylogenetic analysis based on the protein-coding genes revealed that Akanthomyces and Samsoniella were sister genera. Compared with other species of Cordycipitaceae, A.lecanii had a small mitochondrial genome. Except several species, other species of Cordycipitaceae had good mitochondrial genome collinearity. [Conclusion] We obtained the full-length mitochondrial genome sequence and related information of A.lecanii. The phylogenetic analysis supports the independent taxonomic status of A. lecanii, and the mitochondrial genomes of fungi belonging to Cordycipitaceae are conserved.