Sequencing And Analysis Of Mitogenomes Of Locusta Migratoria Tibetensis And Locusta Migratoria Manilensis

Locusta migratoria tibetensis and Locusta migratoria manilensis belongs to Locusta L, Oedipodidae, Aridoidea, Caelifera, Orthoptera. There are 9 geographical subspecies in Locusta L, three of which are distribution in China, viz: Locusta m. manilensis, Locusta migratoria migratoria and Locusta m. tibetensis. Traditional view is that Locusta m.migratoria distributed in Inner Mongolia-Xinjiang Plateau, Locusta m. manilensis in the vast area of North China and south of North China, and Locusta m. tibetensis in area of Tibet.In this thesis, the materials are Locusta m.tibetensis which was collected in Yushu of Qinghai province and Locusta m. manilensis in Baoding of Hebei province. We extracted the total DNAs of the two subspecies by Proteinase K digestion method, and design the primers according to homologous nucleotide sequence, expand and determinated the sequence of the mtDNA of the two subspecies. We analyze the sequence of two subspecies (Locusta m. tibetensis and Locusta m. manilensis) by ClustalX, DNAMAN and MAGE,and download the mtDNA of the Locusta m. migratorioides (NC-001712) and Locusta m. migratoria (NC-011119) from GenBank, and reconstruct the phylogenetic tree basis on 4 subspecies by MP, NJ, BI. Come to the conclusion that.1 The mitogenome length of Locusta m. tibetensis and Locusta m. manilensis is 15568bp and 15902bp, respectively. The mitochondria of the two subspecies is circular, it includes 13 protein coding genes (PCGs), 22 transfer RNA (tRNA) coding genes, ribosomal RNA genes and a noncoding region A+T-rich region. There are 23 genes in majority-strand (H-chain) that includes 9 protein coding genes (PCGs) and 14 transfers RNA (tRNA). In minority-strand (L- chain), there are 14 genes that include 4 protein coding genes (PCGs), 8 transfers RNA (tRNA) and 2 RNA (lrRNA, 16s and srRNA, 12s). In the both sequence of the mtDNA shows a high bias towards A+T, especially in A+T-rich region. This feature is nearly the same as the characteristic of the mitogenome arthropod.2 There are genetic overlaps and gene spacers in the mtDNA sequences of Locusta migratoria tibetensis and Locusta migratoria manilensis. In the mtDNA sequences of Locusta migratoria tibetensis, there are 36bp in the 5 regionals of genetic overlaps. The length rang of the overlaps from 2 to 12bp and the average length is 7.5bp. In mtDNA sequences of Locusta migratoria manilensis, exist 6 regionals of genetic overlaps, and the munbers of base are less 8bp than Locusta migratoria tibetensis, it is 28bp, the average length is 4.67bp.There are 106bp in 17 gene spacers of mtDNA sequence of Locusta migratoria tibetensis, the average interval is 6.24bp. In the sequence of mtDNA of Locusta migratoria manilensis, it exsit 104bp in 16 gene spacers, the average interval is 6.5bp. The more overlapping genes and the less bases intervals in mtDNA indicating that the base arrangement of mitogenome are more closely and properly, in addition, the use of bases is more optimization.3 Start codons of all protein-coding sequences in both Locusta migratoria tibetensis and Locusta migratoria manilensis are ATN except coxI. In this study, we infer ATGA is the start codon of coxI of both mitogenome. All termination codon of protein-coding sequences is complete (TAA), except one TA and five sigle-base T. At present, many scholars believe that the incomplete stop codons will become typical TAA codon by post-transcriptional polyadenylation. This reasoning shows that the utilization about mitochondrial genes is effective.4 All tRNAs of mtDNA could form typical clover leaf structure by Scan-tRNA softwaer, except trnS(AGN) that lacks of the dihydrouracil arm.5 In this paper, we reconstructed the phylogenetic trees based on the sequence of all protein genes of four subspecies by MEGA 4.1、PHYLIP and MrBayes 3.1.2. The results show that the closest relationship is Locusta migratoria manilensis and Locusta migratoria tibetensis, the similarity is 100. The relationgship of the four subspecies is (((Locusta.m.tibetensis, Locusta.m.manilensis), Locusta.m.migratoria), Locusta.m.migratorioides). This supports the traditional view which is that Locusta L. distributed in Inner Mongolia-Xinjiang Plateau is Locusta m.migratoria, in the vast area of North China and south of North China is Locusta m. manilensis, and in area of Tibet is Locusta m. tibetensis which supports its subspeices taxonomic position.