Reanalysis of the mitochondrial genome of the nematophagous fungus Hirsutella rhossiliensis

Abstract:

[Objective] To identify the mitochondrial genome (mitogenome) of Hirsutella rhossiliensis OWVT-1 strain, verify erroneous sequences present in the published USA-87-5 mitogenome, and perform comparative mitogenomic analyses of three Hirsutella species.[Methods] The OWVT-1 mitogenome was assembled based on high-throughput DNA sequencing data and Sanger sequencing. PCR assays were performed to verify 3 long varying regions observed during alignment between the published USA-87-5 mitogenome and OWVT-1 mitogenome assembled in this study. Bioinformatics analyses were used to annotate the mitogenome sequence of OWVT-1.[Results] We detected several sequence errors in the published USA-87-5 mitogenome, including long sequence insertions/deletions and small indels. The mitogenomes of OWVT-1 and USA-87-5 were identical without any nucleotide difference. The complete mitogenome of H. rhossiliensis was 62949 bp in length, with 13 introns in seven genes. Several introns and intergenic regions seemed to have degenerated. The mitogenomes of H. rhossiliensis, H. vermicola, and H. minnesotensis showed a high synteny. Except free-standing ORFs, the gene order of core protein-encoding genes, rRNA genes, and tRNA genes were highly conserved among the three Hirsutella mitogenomes. The length at intergenic regions was a main factor affecting mitogenome sizes of different Hirsutella species.[Conclusion] There were erroneous sequences in the published USA-87-5 mitogenome. We reported the authentic mitogenome sequence of H. rhossiliensis using the highly virulent strain OWVT-1.