Sequencing And Analysis Of The Mitochondrial Genome Of A Host Insect Of Ophiocordyceps Sinensis

Hepialidae insects are the dominant hosts of Ophiocordyceps sinensis.O.sinensis is known as the three treasures of traditional Chinese medicine.O.sinensis parasitizes on the larvae of the ghost moth Thitarodes,which live in alpine meadows of Tibetan Plateau.The hosts of O.sinensis are ideal materials for the Lepidoptera Hepialidae insects and evolution research,due to the different climate types and terrain among different regions on the Tibetan Plateau,and abundant species diversity.Mitochondria is an important semi-autonomous organelle,which records abundant informations that organism evolve from simple to complex and from lower to higher.Because of their unique features,including coding content conservation,maternal inheritance,and rapid evolution,mitogenome sequences have been widely used as molecular markers for diverse evolutionary studies.Therefore,the study of mitochondrial genomes of host insects of O.sinensis is also a hot spot in recent years.To date,mitochondrial genomes(mitogenomes)of 9species of Hepialidae insects(7 of 9 are hosts of O.sinensis)have been released in the NCBI,but there is no data of Thitarodes sp.which was studied in this paper;In addition,it was compared with the reported mitochondrial genome of the Hepialidae insects.In this paper,we collected Hepialidae larva(Thitarodes sp.)from Heishui County,Sichuan Province;We designed primers according to 7mitochondrial genomes of O.sinensis host insects;Then,we assembled the complete mitogenome of Thitarodes sp.by multiple PCR amplification and cloning.At present,the length of the obtained mitochondrial genome was14,970 bp in length,but the whole mitochondrial genome was predicted to be between 16 and 17 kb.According to gene annotation results,the mitochondrial genome of Thitarodes sp.contained 13 typical protein codinggenes(PCG),containing three subunits of cytochrome C oxidase(cox1,cox2,cox3),two subunits of ATP synthase(atp6,atp8),cytochrome-b gene(cob),seven subunits of NADH dehydrogenase complex(nad1,nad2,nad3,nad4,nad4 L,nad5,nad6),two subunits of rRNA(rnl and rns),and 21 tRNA genes.According to the conservation of the mitochondrial genome sequence,there is no amplification of tRNA I and AT-rich region at present.we compared with mitogenome sequence of Thitarodes sp.and other nine Hepialidae insects.The result showed that some aspects had higher uniformity including the genome composition,sequence,codon usage,base content,amino acid frequency,gene interval and overlap region of the mitochondrial genome;But in some areas there were some differences;In terms of genetic gaps,two non-O.sinensis host insects and 8 O.sinensis host insects had some differences.This study enriched the mitochondrial DNA information of the O.sinensis host insects and provided some theoretical basis for further understanding the species development and utilization of O.sinensis,the protection of resources and the protection of habitat.Because the Hepialidae insects are the dominant insects of O.sinensis,this study provides some biological information for understanding the evolution of the Hepialidae insects and some evidences for the study of the development and evolution of the Lepidoptera insects.