五种索科线虫RAPD亲缘关系分析

Genetic Relationships Among Five Species of Mermithidae Based on RAPD

采用RAPD技术构建了索科线虫4属5种的指纹图谱.从47个引物中筛选出12个稳定性好、多态性高的引物,共扩增出161条谱带,其中150条谱带具遗传多态性,占93.17%.所获片段长度大小为200～3 200 bp,单个引物扩增的条带数在11～16之间,平均为13.42条.采用RAPDistance软件及MEGA程序,计算Nei氏相似系数和遗传距离,建立UPGMA和NJ聚类图,两个聚类图拓扑结构相同,将5种索科线虫分为两大分支:同属于蚊幼寄生罗索属线虫的食蚊罗索线虫(Romanomermis culicivorax)与武昌罗索线虫(R. wuchangensis)亲缘关系最近,先聚在一起,再与同翅目(Homoptera)寄生长沙多索线虫(Agamermis changshaensis)聚为一支;鳞翅目(Lepidoptera)寄生中华卵索线虫(Ovomermis sinensis)和同翅目寄生两索属线虫(Amphimermis sp.)亲缘关系较近,两者聚为一支.5种索线虫属内种间的遗传距离较小,食蚊罗索线虫与武昌罗索线虫之间遗传距离仅为0.1789;而属间遗传距离较大,在0.4471～0.5488之间.上述结果表明:RAPD技术可以应用于索科线虫亲缘关系的分析,能够反映出不同线虫间的遗传差距,从而成功地进行属、种的分类及进化问题研究.

In this study, the genetic relationships among five species belonging to four genera of Mermithidae were detected using RAPD.??Twelve?primers?were?screened?from?47?random?primers?and?amplified?161?bands??(from?200?bp?to 3 200 bp). 150 (93.17%) of these bands were polymorphic bands. The number of obtaining segments of individual primer was between 11-16, the average was 13.42. Nei's similarity coefficients and genetic distance were calculated using the RAPDistance and MEGA softwares. The phylogenetic trees were constructed with the methods of UPGMA and NJ. The results from two methods of cluster analysis were similar in general, and the relationship indicated the five species of Mermithidae could be distinguished with RAPD markers and were grouped into two distinct clusters. In the phylogenetic trees, Romanomermis culicivorax and R. wuchangensis (all parasite in larvae of mosquitoes) grouped together, then they grouped with Agamermis changshaensis (parasite in Homoptera) into one cluster. Ovomermis sinensis (parasite in Lepidopters) grouped with Amphimermis sp. (parasite in Homoptera) into one cluster. The genetic distances of five Mermithidae species showed that the relationships of intra-genus were nearer than that of inter-genus, the genetic distance between R. culicivorax and R. wuchangensis was 0.1789, but the genetic distance between inter-genus were 0.4471-0.5488. All those results suggested that RAPD was suitable for analysis of phylogenetic relationship among species of Mermithidae.