Molecular Systematics Studies Of Acridoidea Based On 16SrDNA&COII Genes

Acridoidea are the most important part of Orthoptera, and they play a variety of roles in the food chain. Acridoidea are irreplaceable in maintaining ecosystem stability. Acridoidea have tremendous impact on the development of agriculture, animal husbandry and forestry. They are closely linked with human life. Therefore, the study on Acridoidea has great significance.The systematics study is the hot point in the Acridoidea research. Traditional taxonomy which can not meet the demands of modern research is mainly based on the morphology. In this study, phenol- chlorine extraction, PCR amplification and DNA sequencing have been used, and Bio Lign, MEGA5.05, PAUP4.0, Mr Bayes3.1.2 were used to analyse datas. After the analysis of sequence composition, nucleotide substitution, codon usage, amino acid composition and nucleotide substitution saturation for 16 Sr DNA and COII genes of 16 species grassshopers, usemaximum likelihood method, maximum parsimonymethod, neighbor joining method and bayesian inference to make phylogenetic trees.Through data analysis, the main conclusions are as follows:(1) Acridoidea mt DNA has obvious A + T bias. The amount of A+T is 71.2% in16Sr DNA gene. The amount of A+T is 71.8% in COII gene.(2) The proportion of conservative sequences is 66.5% in 16 Sr DNA gene. The proportion of conservative sequences is 53.2% in COII gene. 16 Sr DNA gene is more conservative than COII gene. Meanwhile, the variation can be retained easily in the thirs gene site.(3) The COII gene uses the codons of AUU(21.3), UUA(17) and ACA(12.1) more frequently.The codons of CUG, UCG and GCG don’t exist in COII gene. The differences of codon frequency may be associated with the amount of different t RNA. The COII gene uses more isoleucine(11.57), leucine(11.49) and serine(9.72) in amino acid analysis.(4) The uncorrected P-distance of 16 Sr DNA for 16 species grassshopers ia between 0.006-0.151. The uncorrected P-distance of COII gene for 16 species grassshopers is between 0.007-0.236.(5) The relationships of P-distance and R values, TS, TV, prove that the two genes nucleotide substitution are not saturated.(6) In the phylogenetic relationships, Acrididae, Oedipodidae, Gomphoceridae and Catantopidae are mutually monophyletic group. Angaracris rhodopa and Angaracris barabensis are close in genetic relationship, but they are not the same species(95 rating). Oedaleus infernalis and Bryodemella tuberculatum are close in genetic relationship.In this paper, phylogenetic analysis has been done by gene sequencing of 16 Sr DNA and COII genes. And provide a molecular basis for classification system of locusts. In the next step, more grasshopper species and longer gene fragment will be used, in order to obtain more reliable phylogenetic signal.