基于线粒体cox1、nad1和rrn L基因探讨马圆线科线虫间的亲缘关系

Phylogenetic Relationships among Nematodes of Strongylidae Based on Mitochondrial cox1,nad1 and rrnL Sequences

为探讨马圆线科线虫(圆线亚科和盅口亚科)间的亲缘关系,对长伞杯冠线虫(Cylicostephanus longibursatum)、冠状冠环线虫(Coronocyclus coronatus)、细口杯环线虫(Cylicocyclus leptostomus)、拉氏杯口线虫(Poteriostomum ratzii)、麦氏副杯口线虫(Parapoteriostomum mettami)和无齿圆形线虫(Strongylus edentatus)6种线虫的线粒体cox1、nad1和rrnL基因进行扩增,与同科相关线虫进行比较分析。然后以线粒体cox1、nad1和rrnL串联序列为标记基因,采用贝叶斯法(Bayesian inference,BI)构建进化树来探讨圆线科线虫间的亲缘关系。结果显示,研究中6种线虫的cox1序列长度均为1578 bp,nad1的序列长度除无齿圆形线虫为879 bp外,其余均为873 bp,rrnL序列长度均不同,大小为959~980 bp。6种线虫的cox1、nad1和rrnL的AT含量分别为67.55%~69.71%、71.36%~73.83%和80.88%~82.59%。圆线科线虫间cox1、nad1和rrnL基因的相似性分别为83.4%~97.9%、79.0%~98.4%和78.8%~98.9%。值得注意的是,圆线亚科的三齿属线虫与盅口亚科的相似性总体要高于同亚科的圆线属。进化分析显示,三齿属并没有与同亚科的圆线属形成独立分支,而是与盅口亚科线虫聚集在一起。在盅口亚科分支中,并非每一属单独形成一独立分支,冠环属和杯冠属最为明显,为复系。基于马圆线虫线粒体cox1、nad1和rrnL的序列和进化分析表明,三齿属线虫与盅口亚科的关系较圆线亚科更近,支持三齿属应隶属于盅口亚科这一假说。

To explore the relations among the Strongylidae nematodes(Strongylinae and Cyathostominae)in equine,the mitochondrial cox1,nad1 and rrnL genes of six species of nematodes including Cylicostephanus longibursatum,Coronocyclus coronatus,Cylicoc-yclus leptostomus,Poteriostomum ratzii,Parapoteriostomum mettami and Strongylus edentatus were amplified,and a comparative analysis was performed with the related nematodes in the same family.Then,the phylogenetic relationships among the Strongylidae nematodes was explored based on the mitochondrial cox1,nad1 and rrnL tandem genes using Bayesian inference(BI)method.The results showed that the length of cox1 sequence of six nematodes in this study was 1578 bp,the length of nad1 was 873 bp,except for S.edentatus,which was 879 bp,and the length of rrnL was different,ranging from 959 bp to 980 bp.The AT contents of cox1,nad1 and rrnL of six nematodes were 67.55%to 69.71%,71.36%-73.83%and 80.88%-82.59%,respectively.The similarity of cox1,nad1 and rrnL among the Strongylidae nematodes were 83.4%-97.9%,79.0%-98.4%and 78.8%-98.9%,respectively.Significantly,compared to the Strongylus sepcies of Strongylinae,Triodontophorus species had higher similarity with Cyathostominae nematodes.The phylogenetic analysis showed that Triodontophorus nematodes of Strongylinae did not form a single branch,but formed a group with the Cyathostominae nematodes.In the branch of Cyathostominae,not each genus formed a group singly,and Coronocyclus and Cylicocyclus were the most obvious which were polyphyletic.Based on the sequence and phylogenetic analysis of the mitochondrial cox1,nad1 and rrnL of equine strongyles,the results indicated that Triodontophorus species were more closer with Cyathostominae than with Strongylinae,which supported the hypothesis that Triodontophorus species belonged to Cyathostominae.