Yinchuan Oil Gourd And Doe Coffin Head Cricket Mitochondrial Genome Sequencing And Analysis

Orthoptera which is widely distributed throughout the world is one of the largest Orders among the insecta,such as locust,cricket,long-horned grasshopper,mole cricket and so on. Orthoptera group divides into two suborders,Caelifera and Ensifera,the former includes Acridoidea,Tettigonioidea,Tridactyloidea,Tetrigoidea,and Eumastacidae,while Gryllotalpoidea, Grylloidea and Tettigonioidea consist of the latter.The classification of species in Orthopteran has been controversial and complicate.In this paper,the complete mitochondrial genomes of Teleogryllus infernalis and Loxoblemmus doenitzi were sequenced,assemblyed,annotated and analyzed in details.The strategies of long-PCR and sub-PCR are used to finish the whole genome sequencing.The two new mitochondrial genomes combined with that of other 7 Polyneoptera insects,Gryllotalpa orientalis, Locusta migratoria,Periplaneta fuliginosa,Sclerophasma paresisense,Tamolanica tamolana, Pteronarcys princes and Anabrus simplex deposited in GenBank,as well as other 28 Orthoptera species which complete mitochondrial genome were sequenced in our laboratory,were used to reconstructed Orthoptera phylogeny and explored the phylogenetic utility of COⅠ,COⅡ,COⅢgenes.The main conclusions are summarized as following.1.The determined mitochondrial genome sequeces of T.infernalis and L.doenitzi are 15,499 bp and 15,392 bp respectively.T.infernalis and L.doenitzi mitgenome encode 13 putative proteins,2 rRNAs,22 tRNAs and an A+T riched region.2.The gene order and transcription direction are the similar as of Drosophila melanogaster. The typical tRNA N-E order in Arthropoda has invert to tRNA E-[(?)]-N order in this two crickets,so that form the third type of gene rearrangements in Orthoptera.A total of 123 bp overlap regions among T.infernalis mitochondrial genome are found in twenty locations with a total of 32 bp of intergenic spacer in seven locations.L.doenitzi has a 125bp overlap region in nineteen locations and a 88bp intergenic spacer in eight locations.3.The average A+T content of the T.infernalis and L.doenitzi mitochondrial genome protein coding sequence,rRNA,tRNA gene and A+T riched region was corresponding well to the A+T bias generally observed in insect mitochondrial genomes.The strongest A+T biase is found at the A +T riched region,which is nearly 77.0%and 77.3%in T.infernalis and L.doenitzi mitochondrial genomes respectively.4.Except COⅠgene with TCG,the start codon usage of T.infernalis and L.doenitzi mitochondrial PCGs are much the same as that of other insects.12 PCGs used the same as the start codon of ATN.While only the ND5,COⅢgenes of T.infernalis and the ND1,COⅢgenes of L. doenitzi terminate into TA residue,Majority of the 13 PCGs in the two crickets have a complete codon,TAA or TAG.Leucine,isoleucine,serine,phenylalanineare have the hightest composition of all amino acids.5.Except tRNA-Ser[S-AGN],which DHU arm could not form stable stem-loop structure,all of the tRNAs genes of T.infernalis and L.doenitzi have a typical clever-leaf structures and their anticodons are similar to those found in other Hexapoda animals.Most of the size variation among tRNAs stemmed from length variation in the TψC and DHU arms.The G-U pair is found in all the tRNA genes of four arms.The secondary structure of the 12S rRNA and the domainⅣ,Ⅴ,Ⅵof 16S rRNA show a little difference to Ruspolia dubia.6.The phylogenetic relationships of Orthoptera were reconstructed with COⅠ,COⅡ,COⅢgenes and COⅠof 100 insects by MP,ML and Bayesian inference.The monophyly of Orthoptera, Grylloidea and Tettigonioidea is supported by all data.All data sets have poor performance for Acridoidea.The phylogenetic tree of 100-CO1 DNA data set by BI is better than others.Based on molecular study,31-CO1,31-CO2 and 31-CO123 data sets are selected for the attempt to interpret the phylogenetic relationships among Orthoptera.Results show that Grylloidea is closely related to Tettigonioidea,and the phylogenetic relationships of Grylloidea is identical to classicial taxonomic systems.But thoses data sets can not resolve relationships within Acridoidea.In our study,the phylogenetic performance of the 3 genes from good to bad is COⅠ,COⅡ, COⅢin turn.The phylogenetic performance of these mitochondrial genes might depend on the gene length,function and taxa sampling.This work is the first report about the complete mitochondrial genomes on Teleogryllus infernalis and Loxoblemmus doenitzi and discoverd the third type of gene rearrangements in Orthoptera.At the same time,The phylogenetic relationships of Orthoptera were reconstructed with COⅠ,COⅡ,COⅢgenes and the phylogenetic performance of these genes were discussed.It adds two more Orthoptera complete mitochondrial genome sequences to public database,and has accumulated usesful information for mitochondrial phylogenomics research of insect.