绿眼赛茧蜂线粒体基因组全序列测定和分析

Sequencing and analysis of the complete mitochondrial genome of Zele chlorophthalmus(Hymenoptera:Braconidae)

【目的】测定绿眼赛茧蜂Zele chlorophthalmus线粒体基因组全序列,分析其基因组结构及茧蜂科(Braconidae)部分类群的系统发育关系。【方法】利用Illumina MiSeq二代测序技术对绿眼赛茧蜂的线粒体基因组进行测序,对基因组序列进行拼装、注释,分析其结构特点和碱基组成;基于22种茧蜂科昆虫的COX1蛋白编码基因序列,应用最大似然法(ML)和邻接法(NJ)构建系统发育树,分析绿眼赛茧蜂与茧蜂科其他昆虫的系统发育关系。【结果】绿眼赛茧蜂线粒体基因组全长16661 bp(GenBank登录号:MG822749),包含13个蛋白质编码基因、22个tRNA基因和2个rRNA基因,共37个基因,以及1个控制区。线粒体基因组有明显的核苷酸组成的偏倚,AT偏正,GC偏负,其A+T含量为82.83%。基因排列顺序与推测的昆虫祖先的序列不完全一致,tRNA基因7处发生重排。13个蛋白质编码基因均以ATN为起始密码子,以TAA为终止密码子。在22个tRNA基因二级结构中,除tRNA His(H)缺失TΨC环和tRNA Cys(C)仅剩二氢尿嘧啶(DHU)臂和反密码子臂外,其余tRNA基因均能形成典型的三叶草结构。基于COX1蛋白编码序列的系统发育分析结果显示,与绿眼赛茧蜂亲缘关系最近的是同属于赛茧蜂属的雪跗赛茧蜂Z.niveitarsis。【结论】本研究首次获得绿眼赛茧蜂线粒体基因组全序列。结果表明绿眼赛茧蜂隶属于优茧蜂亚科(Euphorinae)赛茧蜂属,并支持赛茧蜂属的单系性。

【Aim】This study aims to sequence and analyze the complete mitochondrial genome of Zele chlorophthalmus,and to explore the molecular phylogenetic relationship of some groups within Braconidae.【Methods】Using Illumina MiSeq sequencing technique,the mitochondrial genome of Z.chlorophthalmus was sequenced,the genome sequences were assembled,annotated and characterized,and then the general features and base composition of the mitochondrial genome were analyzed.To analyze the phylogenetic relationships of Z.chlorophthalmus and other species of Braconidae,the phylogenetic trees of 22 Braconidae species based on mitochondrial COX1 gene sequences were constructed by using maximun likelihood(ML)and neighbor-joining(NJ)methods.【Results】The mitochondrial genome of Z.chlorophthalmus(GenBank accession no.:MG822749)is 16661 bp in length,and contains 37 genes including 13 protein-coding genes(PCGs),22 tRNA genes and 2 ribosomal RNA genes,and one control region(CR).The mitochondrial genome has a clear bias in nucleotide composition with a positive AT-skew and a negative GC-skew,with the A+T content of 82.83%.The mitochondrial gene arrangement of Z.chlorophthalmus is not completely consistent with that of the putative ancestral sequence of insects,and there are seven gene rearrangements in its tRNA genes.All the 13 PCCs start with an ATN initiation codon and terminate with a TAA stop condon.All the predicted tRNA genes show the classic clover-leaf secondary structure,except that tRNA His(H)has no TΨC loop and tRNA Cys(C)only has dihydorouridine arm and anticodon arm.The results of phylogenetic analysis based on the COX1 coding sequence showed that Z.chlorophthalmus had the closest relationship with Z.niveitarsis,which also belongs to the genus Zele.【Conclusion】We firstly sequenced and analyzed the complete mitochondrial genome of Z.chlorophthalmus.The results show that Z.chlorophthalmus belongs to Euphorinae and support the monophyly of Zele.