橡实象虫等25种昆虫线粒体COⅠ基因的遗传多样性及系统进化分析

Genetic Diversity and Phylogenetic Analysis of COⅠ Genes from Curculio arakawai Weevil and 24 Other Insect Species

橡实象虫(Curculio arakawai)是象甲科中危害柞树种子和嫩芽的重要害虫。为探讨利用线粒体细胞色素C氧化酶亚基Ⅰ(COⅠ)基因的特定区段作为DNA条形码快速准确识别橡实象虫的可行性,克隆了3个橡实象虫线粒体COⅠ基因5'端长度约556 bp的片段(GenBank登录号:JN258957,JN258958,JN258959),并与鞘翅目、鳞翅目、双翅目共24种昆虫的同源片段进行碱基组成多样性和系统进化分析。序列分析结果显示:橡实象虫与其它24种昆虫的COⅠ基因序列呈现丰富的遗传多样性,碱基位点的变异率为48.2%,序列平均差异为19.7%;COⅠ基因序列的AT含量(69.9%)明显高于GC含量(30.1%),存在显著的AT使用倾向性;碱基替换模式颠换大于转换,碱基替换数与物种两两遗传距离呈明显的线性关系;COⅠ基因序列的碱基变异速率较快的位点主要集中在序列中间区域的210～390 bp。基于COⅠ基因序列构建的NJ、ME和MP系统进化树均显示橡实象虫与鞘翅目象甲科(Curculionidae)昆虫的进化关系最近,聚在一起形成一个分支,鳞翅目等其它昆虫聚在一起形成另外一个分支;橡实象虫与鞘翅目象甲科Kyklioacalles属昆虫间遗传距离最小,与鳞翅目丝角蝶科Macrosoma sp.属昆虫间的遗传距离最大。根据COⅠ基因序列的多样性,能将橡实象虫明显地与其它昆虫区分开。

Acorn weevil（Curculio arakawai） is the major pest in family Curculionidae damaging acorns and buds of oak tree.To discuss the possibility of using the specific region in cytochrome C oxidase subunitⅠ（COⅠ） gene of mitochondrial DNA（mtDNA） as DNA barcode for fast and accurate identification of acorn weevil,a 556 bp segment in 5′ region of COⅠgene from three acorn weevil individuals were cloned and sequenced（GenBank No.JN258957,JN258958 and JN258959） and were subsequently analyzed on their base composition diversity and pholygenesis with homologous fragments of 24 other insect species from Coleoptera,Lepidoptera and Diptera.The result of sequence analysis showed that there was great genetic diversity in COⅠ gene sequ-ences between acorn weevil and 24 other insect species,with base variation ratio of 48.2% and average sequence distance of 19.7%.The average content of A＋T（69.9%） in COⅠ gene was obviously higher than that of G＋C（30.1%）,showing a strong A＋T bias.Base substitution mode was more in transversion than in transition,and the number of substituted bases showed obvious linear relationship with p-Distances.The highly variable sites in COⅠ gene sequences were mainly located within 210 ~390 bp,the middle part of the fragment.The constructed NJ,ME and MP phylogenetic trees based on COⅠ gene sequences showed that acorn weevil had the closest phylogenetic relationship with insect species from Coleoptera： Curculionidae,all of which formed a monophyletic clade.Other insect species from Lepidoptera etc clustered together and formed another monophyletic clade.Acorn weevil had the closest genetic relationship with the genus Kyklioacalle of Coleoptera： Curculionidae and the farthest genetic relationship with Macrosoma sp.of Lepidoptera： Hedylidae.Based on the sequence diversity of COⅠ gene,acorn weevil can be distinguished clearly with other insect species.