Genome Sequence Analysis And Genealogical Analysis Of Mitochondria Of Two

Tettigonioidea is a superfamily of Ensifera in Orthoptera, and is regarded as the largest taxa of Ensifera with more than 7000 species. In recent years, along with the recognitions of their important status in phylogenetic and systematic research, studies about Tettigonioidea began to increase. There are only 20 Tettigonioidea mitochondrial genomes in GenBank database.We determined almost the entire motochondrial genomes of Phyllomimus sinicus and Nipponomeconema sinica by PCR amplification and sequencing. The new mitochondrial genomes were annotated with reference to the mitochondrial genome informations of Mecopoda niponensis and Ruspolia dubia. Combining with other Ensifera mitochondrial genomes in the database, nucleotide composition, amino acid composition, and codon usage were compared, and phylogeny of Ensifera was reconstructed. The main conclusions drawn from this study were listed below:1. The obtained sequences length of Phyllomimus sinicus and Nipponomeconema sinica mitochondrial genomes are 14884bp and 14814bp respectively.13 protein coding genes and 16S rRNA can be annotated, but some of the tRNAs, part of 12S rRNA gene and D-loop region were not sequenced through. Phyllomimus sinicus and Nipponomeconema sinica with the same gene order with the other Tettigonioidea mitochondrial genomes.2. Phyllomimus sinicus and Nipponomeconema sinica mitochondrial genomes have a high A+T content, the average A+T content are 73% and 72.8% respectively. All protein-coding genes of Ensifera motochondrial genomes in this study have an obvious AT skew, especially the third codon base. Phyllomimus sinicus conforms to this characteristic, but Nipponomeconema sinica don’t accord with the characteristics with its third codon of A+T content is less than the first、second codon, and find that A+T content is minimal whether in the NPCG or JPCG, third codon.3. Most protein genes use the typical start codon ATN, except COX1 gene of all two species (ACC, TTA). Most protein genes use the typical and complete stop codon:TAA, TAG and incomplete stop codons:TA or T.4. All the 22 tRNA genes of Phyllomimus sinicus and Nipponomeconema sinica mitochondrial genomes have a typical clover leaf structure except tRNA Ser(AGN), which lack the DHU arm. The complete secondary structures of the 16S rRNA genes are predicted. There are 48 stem-loop structure of 16S. Most parts of the secondary structure among different species are similar.5. Phylogenetic relationships of Ensifera insects were reconstructed with four different datasets, mitochondeial genome、all protein-coding genes、22 tRNA genes and two rRNAgenes. All results support two subfamily Tettigonioidea and Gryllotalpodea as monophyletic groups, not support subfamily Gryllidea as monophyletic groups. Bradyporidae and Tettigoniinae always clustered together. Meconematidae as monophyletic groups, but Conocephalidae and Pseudophyllidae were not accepted as monophyletic groups respectively. Pseudophyllidae and Mecopodidae have closely relationships.