| Thitarodes pui and Napialus hunanensis are two valuble species which could seperately form Ophiocordyceps sinensis(Berkeley) Saccardo and its succedaneum Cordyceps hawkesii Gray. And it is well known that O. sinensis is a precious medicine and invigorant in China. However, these two species remained poorly known on molecular level. Therefore, the mitochondrial genomes of T. pui and N. hunanensis are not only considered as natural resources, but also in favor of species identification and phylogenetic analyses of T. pui and N. hunanensis.In this study, the complete mitochondrial genomes of T. pui and N. hunanensis were sequenced, annotated and analyzed through various biosoftwares. Compared to two known species in Hepialidae(Ahamus yunnanensis and T. renzhiensis), genetic structures and base compositions of two mitogenomes were analyzed. Finally, 13 protein coding genes and 2 rRNA genes among 39 species in Lepidoptera were combined and then applied to constructe 4 different trees seperately by maximum parsimony methods in Paup 4.0, maximum likelihood(ML) in PhyML 3.0, bayesian inference methods(BI) in MrBayes as well as neighbor joining method(NJ) in Mega 6.0. The conclusios were presented as below:1. The complete mitochondrial genomes of T. pui and N. hunanensis were 15, 064 and 15, 301 bp, both contained 13 protein coding genes, 2 rRNA, 22 tRNA as well as an AT rich region as descrided in other Lepidoptera insects. The rearrangment of tRNA appeared as t RNAIle-tRNAGln-tRNAMet between AT rich region and ND2 instead of the stand set showed as tRNAMet-tRNAIle-tRNAGln among Lepidoptera, which is considered as an ancient arrangment. The highly AT biased with the AT contents of 80.73%, 81.85% were observed in T. pui and N. hunanensis mitogenomes.2. Various start and terminate codons were observed in T. pui and N. hunanensis. Except both COX1 genes initiatied with CGA and ND1 in N. hunanensis started with TTG, the remaining genes in both species were started with the typical ATN. Major genes in both were terminatied with TAA or single T while ND3 in T. pui was stopped with TAG. These coding genes were analzied on codonusage. Result showed UUU(F), UUA(L), AUU(I), AUA(M) were most abundant. In terms of amino acids, Cys was least frequently used with the content of 0.75% in both T. pui and N. hunanensis mitogenomes.3. The size of 22 tRNA genes in both mitogenomes ranged from 59 to74 bp. It is noteworthy that tRNASer(AGN) genes could not be folded as standard cloverleaf structure as other tRNA genes in both mitogenomes, and the mismacth was common in tRNA genes.4. AT rich region in T. pui mitogenome was 287 bp with an AT content of 92.33% while it was 368 bp in N. hunanensis mitogenome with the AT content of 93.21%. Both AT rich regions were much shorter than that in A. yunnanensis(978 bp) and T. renzhiensis(1, 367 bp). The two rich regions showed different structures. In T. pui mitogenome, the AT rich region contained 2 long tandem repeats and 3 Ploy-A while AT rich region in N. hunanensis mitogenome was composed of 4 Ploy-T, 1 Ploy-A as well as(TA)9,(AT)6 and(AT)8.5. Four known gohst moths in NCBI showed highly similarity with each other. By aligment of the four mitogenomes, numerous tag sequences chould be chosen for indentification of O. sinensis.6. The four different phylogenetic trees showed that four ghost moths were clustered togather and seperated with other Lepidoptera insects which confirmed that four ghost moths may turn out to be ancient insects. Besides, Yponomeutoidea and Tortricoidea were the second and third groups which sperated from other Lepidoptera insects. Moreover, Hesperioidea insects were clustered with Papilionoidea insects as described as(Papilionidae +(Hesperioidea +(Pieridae +(Nymphalidae +(Lycaenidae + Riodinidae))))), which is contrary to traditional taxonomy. Our study also proved that Noctuoidea and(Geometroidea + Bombycoidea)) grouped togather and formed a sister group. |
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