木通红喀木虱线粒体基因组的测定与序列分析

Sequencing and Analyzing Mitochondrial Genome of Cacopsylla coccinea

为保护木通等药用植物资源,了解其生物学性质,寻找其生理生化特性,以木通红喀木虱Cacopsylla coccinea为研究对象,测定了该研究对象的线粒体基因组并分析了其序列特征。采用PCR扩增、基因克隆等技术成功测得木通红喀木虱全线粒体基因组,全长为14 832 bp,共编码37个基因,包括13个蛋白质编码基因、22个转运RNA基因,2个核糖体RNA基因和一个富含AT的非编码区。以木通红喀木虱、枸杞木虱和脉斑银木虱三种昆虫为材料,采用比较基因组学和生物信息学方法,分析木虱科线粒体基因组的分子组成特征。主要组成特征:(1)三种昆虫基因组大小相似;(2)木通红喀木虱线粒体trnV基因发生重排;(3)脉斑银木虱间隔区最长,而枸杞木虱重叠区为最大;(4)三种昆虫AT含量基本相似,均约为70%;(5)三种昆虫存在碱基不对称,其中H-链和L-链上的第3个密码子位点AT的含量远高于其它位点;(6)三种昆虫线粒体基因组中nad5、nad6和cob基因的碱基置换率均小于1,说明它们受到负选择作用。

In order to protect the medicinal plant resources such as Cacopsylla and to discover its biological properties,physiological and biochemical characteristics,we chosen Cacopsylla coccinea as the research object,conducted the determination of its mitochondrial(mt)genome,and analyzed its sequence characteristics.With the technology of PCR and gene cloning,the present study proved that the complete mitochondrial genome(MG)of C.coccineae was 14 832 bp of a full length.It encoded 37 genes,including 13 protein-encoding genes,22transferred RNA genes,2 ribosomal RNA genes,and 1 non-coding region with high AT content.Using 3 insects of C.coccineae,Paratrioza sinica and Pachypsylla venusta as study material,we analyzed the molecular composition features of Psyllidae mitochondrial genome with comparative genomics and bioinformatics,and the results were as follows:(1)the sizes of MG from 3 insects were similar;(2)trnV gene in C.coccineae rearranged while compared with the other 2;(3)the interval in P.venusta was the longest,and the overlap area in P.sinica was the largest;(4)AT contents in 3 insects were similar,with about 70%;(5)Base mismatch in 3 insects existed,with the highest AT content of3rd-site codon in H-strand and L-strand;and(6)the base substitution rate of nad 5,nad6 and cob genes in MG was<1,indicating that they were under negative selection.