Research On Phylogeny Of Achilidae Based On Complete Mitochondrial Genome

Achilidae(Hemiptera:Auchenorrhyncha:Fulgoroidea)are distributed worldwide with 161genera and nearly 520 described species.There are 24 genera and 78 described species in China.Nymphs of Achilidae are herbivore or subterranean on humus,while adults are herbivore.This family,include a large number of important agricultural pests or potential pests in agriculture and have certain economic significance.At present,phylogenetic relationship and higher order classification of Achilidae is not fully understood.Previous phylogenetic research lacks mitochondrial genome data.In this study,we extracted DNA,sequenced,described and compared sequences.Based on mitochondrial genome data,further studies were carried out on phylogenetic status,monophyletic test,phylogenetic relationship reconstruction and construction of taxonomic system.The purpose of this study is to provide reference materials for the study of systematic evolution of Auchenorrhyncha insects,biology and ecology of agricultural and forestry pests,species identification and control of agricultural and forestry pests.The main research contents and results are as follows:1.Description of the mitochondrial genome of genus and species of Achilidae.(1)The mitochondrial genome of 40 species of Achilidae were sequenced.There were 3 tribes,24 genera and 40 species of Achilidae,in the proportion 75%,96%and47%,respectively.The basic structure,nucleotide composition and codon usage,protein-coding gene(PCG),RNA gene and non-coding region of the mitochondrial genome were described.(2)The mitochondrial genome characteristics of Achilidae were identified.Basic structure:It contain 37 genes,of which 14 genes were encoded by N chain(8 t RNA genes,4 PCG genes and 2 r RNA genes)and 23 genes encoded by the J chain(14 t RNA genes and9 PCG genes).Nucleotide composition and codon usage:the nucleotide composition and amino acids usage codons frequency shows obvious AT bias.Some GCG and GGG codons are not involved in amino acid coding at all.Protein-coding gene:Initial codon is ATN and GTG.Termination codon is the complete TAA and TAG or the incomplete T and TA.RNA genes:The anticodon is not mutated.Except for the dihydrouracil(DHU)arm of t RNA^Ser(AGN)that could not form a typical stem ring structure,the others could fold into a typical secondary cloverleaf structure.Ribosomal RNA large subunit was located between t RNA^Leu(CUN)and t RNA^Val,while the small ribosomal RNA subunit was located between t RNA^Valand the control region.Non-coding region:In most cases,contains several or more than a dozen intergenic nucleotide,among which the largest non-coding region is located between sr RNA and t RNA^Ile.The AT rich region often contains a few of repeat sequences.2.Comparative analysis of mitochondrial genome of Achilidae(1)The size of mitogenomes of Achilidae is between 14.8 kb-16.4 kb.The variation in the genome size is due to the number and size of non-coding regions.There is no significant difference in the size of mitogenomes between tribes,genera and species.(2)Gene composition and arrangement usually observed,and no gene addition,deletion or rearrangement.There are short spaces or even overlaps between genes in mitochondrial genomes.A seven-bp overlap(ATGATAA)between ATP8 and ATP6,eight-bp overlap(ATGTTTAA)between ND6 and Cyt B,and eight-bp overlap(AAGCCTTA,except Usana lineolalis)between trn W and trn C were found in this study.Overlap is relatively consistent among tribes,genera and species of Achilidae.(3)The nucleotide composition of the mitogenome was AT bias and between72.60%-78.80%with an average of 76.24%.Rhotalini was 77.50%,Achilini was 75.65%and Plectoderini was 74.81%.AT bias showed a significant regularity among tribes,genera and species.(4)Protein-coding genes usage frequency of the PCG initiation codon ATN was higher than GTG,complete termination codon TAA and TAG were higher than incomplete termination codon T or TA.(5)The ND4L gene had highest rate of evolution,the Cyt B gene was the most conserved.Rhotalini had the highest rate of evolution,while Plectoderini was the most conserved.Rate of evolution did not show a significant regularity between tribes,genera and species.3.Research on evolutionary status of Achilidae(1)The 13 families in the analysis of superfamily Fulgoroidea is divided into two branches:Delphacidae and Cixiidae,which is located at the root of the phylogenetic tree.Achilidae with the other ten Fulgoroidea families(Fulgoridae,Derbidae,Tropiduchida,Flatidae,Issidae,Tettigometridae,Ricaniidae,Nogodinidae,Lophopidae and Eurybrachidae)form another branch.In this large branch,Achilidae(except Rhotalini)and Derbidae,Fulgoridae form a branch,while Tropiduchidae,Flatidae,Issidae,Tettigometridae,Ricaniidae,Nogodinidae,Lophopidae and Eurybrachidae form another branch.(2)In the Fulgoroidea,Achilidae(except Rhotalini)and Derbidae,Fulgoridae is consistently a sister groups that is relatively ancient with well supported basal position.(3)The 12 genera in the analysis of Achilidae,formed 3 stable single branches,but one of them(Rhotala and Errada which belongs to Rhotalini)did not cluster with the other two branches on the large branch line.It is suggests that existing Achilidae maybe a paraphyletic group,and its monophyletic character is not supported by mitochondrial genome data.4.Phylogenetic analysis among the Achilidae(1)Well supported monophyletic lineage between Rhotalini,Achilidae and Plectoderini.(2)Rhotalini is a relatively ancient group,while Plectoderini is a relatively young group.(3)Also supported monophyletic lineage between Rhotala,Catonidia,Magadha and Kosalya.(4)Rhotala+Errada,Catonidia+Paracatonidia,Tegulaconcavus+Hamba,Peltatavertexalis+Spino,Phenelia+Magadha and Betatropis+Semibetatropis are consistently clustered together as sister groups.