The mitochondrial genome of Qinghuang_1, the first modern improved strain of Chinese oak silkworm, Antheraea pernyi (Lepidoptera: Saturniidae)

Abstract

Chinese oak silkworm, Antheraea pernyi Guérin-Méneville 1855 (Lepidoptera: Saturniidae), is a traditional edible insect in China and is considered the edible insect with the highest potential. Information on the mitochondrial genome (mitogenome) of the first modern improved strain of this silkworm, Qinghuang_1, is currently unavailable. Here, we determine the mitogenome of Qinghuang_1 by long PCR amplification followed by Illumina sequencing and then compare the resulting mitogenome with the five available mitogenomes of this species. The mitogenome of Qinghuang_1 is 15,573 bp in length and exhibits an identical gene organisation to known A. pernyi mitogenomes. The base A content of this mitogenome is higher than those of the other four strains but lower than that of the wild type. Sequence comparisons identified 200 single-nucleotide variants (1.28%) and 32 amino acid changes among the five inbred strains, indicating a considerable degree of nucleotide diversity in the mitogenomes of A. pernyi germplasm resources. The 3’ end of ND1 was identified as a hotspot in the A. pernyi mitogenome. Ka/Ks analysis indicated that all protein-coding genes evolved under negative selection except for ND5, which presented values larger than 1, suggesting that positive selection may act on this gene. The phylogenetic analyses confirmed the basal position of Qinghuang_1 among the inbred strains of A. pernyi. Our results indicated that the mitogenome is helpful for understanding the intraspecific phylogenetic relationships of A. pernyi and for its genetic improvement.