栎黄掌舟蛾线粒体DNA COⅠ基因的碱基组成及系统进化分析

Base Composition and Phylogenetic Analysis of Mitochondrial DNA COⅠ Gene from Phalera assimilis

栎黄掌舟蛾(Phalera assimilis)是危害柞树的主要食叶害虫之一。克隆了栎黄掌舟蛾不同个体线粒体细胞色素C氧化酶亚基Ⅰ(mtDNA COⅠ)基因5'端709 bp片段序列(GenBank登录号:KC573812～KC573814),通过与其它鳞翅目昆虫的同源序列比对,分析栎黄掌舟蛾mtDNA COⅠ基因序列片段的碱基组成及系统进化特点,从分子水平准确鉴定该柞树害虫。栎黄掌舟蛾及其比对昆虫的mtDNA COⅠ基因片段序列中,T、C、A、G 4种碱基的平均含量分别为39.8%、14.8%、30.9%、14.5%,密码子第3位点的A+T含量最高达94.2%,显著高于第1位点(59.9%)和第2位点(58.3%),碱基使用显著倾向于T(AT平均偏倚度为-0.125 9);在709 bp的序列片段中,16.36%为简约信息位点,4.51%为单突变位点,碱基转换略高于颠换,R值为1.2;不同昆虫mtDNA COⅠ基因序列间的平均遗传距离为0.054 1。克隆的栎黄掌舟蛾mtDNA COⅠ基因序列片段的T、C、A、G 4种碱基平均含量分别为38.7%、15.2%、31.3%、14.8%;所有样本的mtDNA COⅠ基因序列碱基替换数均与遗传距离呈显著线性关系。系统进化分析显示,栎黄掌舟蛾等掌舟蛾属(Phalera)昆虫与Datana属、Antheua属昆虫的亲缘关系最近,形成进化群Ⅰ,其它属种昆虫聚集形成进化群Ⅱ。研究结果表明,mtDNA COⅠ基因序列片段能作为DNA条形码将栎黄掌舟蛾与其它鳞翅目昆虫区分开。

Phalera assimilis is one of the major pest damaging oak leaves.A 709 bp segment of cytochrome C oxidase subunit Ⅰ（COⅠ） gene was cloned from mitochondrial DNA of different P.assimilis individuals（GenBank accession No.KC573812~KC573814） and compared with homologous sequences from other lepidopterous insects to analyze their base composition characteristics and phylogenetic evolution for accurate identication of P.assimilis at molecular level.The results indicated that the average content of T,C,A and G in segments of mtDNA COⅠgene from P.assimilis and other lepidopterous insects was 39.8%,14.8%,30.9% and 14.5% respectively.The highest A＋T content at the 3rd codon position was 94.2%,being significantly higher than those at the 1st position（59.9%） and the 2nd position（58.3%）.The use of bases showed an obvious T bias（the average skew of AT was-0.125 9）.There were 16.36% parsimony-informative loci and 4.51% singleton loci in the 709 bp segments.Base transition was slightly higher than base transversion（R value was 1.2）.The average genetic distance between mtDNA COⅠ gene from various insect species was 0.054 1.The average content of T,C,A and G in segments of COⅠ gene cloned from P.assimilis was 38.7%,15.2%,31.3% and 14.8% respectively.The number of substituted bases in mtDNA COⅠ gene from all samples showed obvious linear relationship with genetic distance.Phylogenetic tree displayed that P.assimilis and other Phalera insect species had the closest relationship with genus Datana and Antheua,all of which formed evolutionary group Ⅰ.The other insect species clustered together and formed evolutionary group Ⅱ.These results demonstrated that mtDNA COⅠ gene can be used as DNA barcode to discriminate P.assimilis from other lepidopterous insects.