Caelifera Locusts Four Mitochondrial Genome Sequence Analysis And Genomic Analysis Of Pedigree

Acridoidea belonging to the Orthoptera, caelifera (Caelifera), their classification at family and subfamily levels has been controversial. Phylogenetic studies based on a single gene or a few genes from mitochondrial DNA have been difficult to solve the phylogenetic relationships, joint analysis of mitochondrial and nuclear gene sequences, entire genome, and integration of molecular data with morphological is currently the main means of research. Currently there were52mitochondrial genomes of Orthoptera insect recorded in GenBank, including38species of Acridoidea, even so there are still unable to meet needs of robust phylogenetic relationships of major taxa of Acridoidea.In this study, the strategies of combined long-PCR and sub-PCR amplification are used to sequence the whole mitochondrial genomes of four Orthoptera species are Shirakiacris shirakii, Xenocatantops brachycerus, Aiolopus tamulus and Trilophidia annulata.. After sequence assembly, annotation and structural analysis, the four new mitochondrial genomes combined with that of other insects deposited in GenBank, as well as other Orthoptera species which completed mitochondrial genome were sequenced in our laboratory were used to reconstructed Orthoptera phylogeny and explored the phylogenetic utility of different combined data set. The main conclusions are summarized as following.1. The mitochondrial genomes of Shirakiacris shirakii, Xenocatantops brachycerus, Aiolopus famulus and Trilophidia annulata are15649bp,15605bp,15593bp and15922bp respectively. They all encode13protein genes:CO Ⅰ、CO Ⅱ、COⅢ、ATP6and ATP8; ND1、ND2、ND3、ND4、ND4L、ND5、ND6and Cytb,2rRNA genes:1rRNA and srRNA,22tRNA genes, and an A+T rich region. The gene order is different with the typical Arthropod which has a KD reset. Compared with Locusta migratoria and Oxya chinensis, the number and length of the integenic region and overlap are much the same. The largest intergenic regions are all located between the tRNASer(UCN) and ND1.2. The average A+T content of Shirakiacris shirakii, Xenocatantops brachycerus, Aiolopus tamulus and Trilophidia annulata mitochondrial genome has strongly the A+T bias. The strongest A+T biase is found in Trilophidia annulata which is nearly76.1%of the four species, the weakest found in Shirakiacris shirakii which is72.3%. Compared 13protein coding genes and the three codon positions of PCGs in four Orthoptera species are also has A+T bias strongly. The third positions all have the highest A+T composition, The highest A+T composition is found in Trilophidia annulata which is nearly88.9%of the four species, the weakest found in Shirakiacris shirakii which is84.8%.3. The start codon usage of Shirakiacris shirakii, Xenocatantops brachycerus, Aiolopus tamulus and Trilophidia annulata mitochondrial PCGs are ATN except CO I and ND2. The start condons of CO I gene in Shirakiacris shirakii, Xenocatantops brachycerus, Trilophidia annulata are ACC, the same as Hieroglyphus annulicornis and Menglacris maculata of Catantopidae; The start condons of ND2gene in Trilophidia annulata are GTG. The stop codon usage of Shirakiacris shirakii and Xenocatantops brachycerus mitochondrial PCGs are all used the same TAN, but several genes such as ND2, CO Ⅰ, CO Ⅱ, ND3, ND5and Cytb in ND5in Aiolopus tamulus and Trilophidia annulata are use an incomplete ternimation codon TA or T. This phenomenon is popular in the other Orthoptera mitogenome.4. All the22tRNA genes of Shirakiacris shirakii, Xenocatantops brachycerus, Aiolopus tamulus and Trilophidia annulata mitochondrial genomes have a typical clover leaf structure except tRNASer(AGN), which is lack the DHU arm. Some mismatched base pairs occur in22tRNA genes, most of the mismatched base pair are G-U pairs.5. The complete secondary structures of the rRNA genes in Shirakiacris shirakii, Xenocatantops brachycerus, Aiolopus tamulus and Trilophidia annulata mitogenome were predicted. Most parts of the secondary structure among different species are similar and relatively conservative, the main differences appear in ring regions and two terminal regions.6. The A+T contents of the A+T-rich regions of the53Orthoptera insects vary from67.4%(Gampsocleis sedakovii) to88.1%(Xenocatantops brachycerus and Aiolopus tamulus). The A+T contents of the A+T-rich regions of Shirakiacris shirakii and Trilophidia annulata are84.8%and86.0%.7. Phylogenetic relationships of Orthoptera insects were reconstructed with three different datasets, all protein-coding genes, deleting the third codon site of all protein-coding genes and two rRNA genes. All results support two suborder Caelifera and Ensifera as monophyletic groups. Within Acridoidea, Pyrgomorphidae and Chrotogonidae always cluster together, so it’s support that two family as one Pyrgomorphoidae, as the basal branch of Acridoidea. Most results show that Oedipodidae as monophyletic groups. Within Catantopidae14species always together as one without Traulia szetschuanensis, which was mostly clustered together with Pampbagidae.4Pampbagidae species always formed a monophylic group, and then clustered together with Catantopidae, so these two family have closely relationships. Phylogenetic relationships of Acrididae, Arcypteridae and Gomphoceridae have closely relationships. This study showed that Catantopidae, Acrididae, Arcypteridae and Gomphoceridae were not accepted as monophyletic groups respectively.