不同地域来源野桑蚕基于线粒体COⅠ序列的遗传多样性和系统进化分析

Genetic Diversity and Phylogenetic Analysis of Wild Silkworm (Bombyx mandarina) from Different Geographical Origins Based on Mitochondrial COⅠ Gene Sequence

家蚕（Bombyx mori）由野桑蚕（Bombyx mandarina）驯化而来,深入分析野桑蚕的遗传多样性,对发掘和利用其基因资源有重要意义。对来自秦巴山区的3份野桑蚕种质材料的线粒体COⅠ基因及其侧翼序列进行测序,并与从Gen Bank数据库中获取的15份野桑蚕、30份家蚕种质材料的线粒体COⅠ序列进行单核苷酸多态性（SNP）位点和遗传进化分析。16份中国野桑蚕种质材料之间、2份日本野桑蚕种质材料之间的COⅠ序列分别存在65个和10个碱基的差异;30份家蚕种质材料的COⅠ序列中只存在7个碱基的差异。与来自中国四川、江苏等地的野桑蚕相比,来自日本、中国山东青州及秦巴山区的野桑蚕具有更为丰富的SNP位点。18份野桑蚕种质材料和30份家蚕种质材料的COⅠ序列共定义了25种单倍型,其中野桑蚕18种,家蚕7种。基于18份野桑蚕种质材料、30份家蚕种质材料的COⅠ序列的聚类分析表明：18份野桑蚕种质材料的聚类与其地理来源存在一定关联性,四川、江苏等地的野桑蚕各自独立成一枝,来自秦巴山区的5份野桑蚕种质材料分别与来自山东青州、四川地区的野桑蚕聚类;家蚕与中国野桑蚕的亲缘关系较近,与日本野桑蚕的亲缘关系较远,而来源于安康市汉阴县、岚皋县、汉滨区及山东青州的野桑蚕又与家蚕的亲缘关系最为接近。研究结果表明即使同是来自秦巴山区的野桑蚕也存在丰富的遗传多样性,研究结果也再次佐证了家蚕起源于中国野桑蚕的论述。

The domestic silkworm（ Bombyx mori） was domesticated from the Chinese wild silkworm（ Bombyx mandarina）. Further analysis of the genetic diversity of wild silkworm is important for exploiting and utilizing its gene resource. In this study,the mitochondrial COⅠgene and its flanking sequences of three wild silkworm germplasm samples collected from Qinling-Daba mountain region（ Shaanxi Province,China） were sequenced. Single-nucleotide polymorphism（ SNP）and genetic diversity analysis were conducted with mitochondrial COⅠgene homologous sequences of 15 wild silkwormsand 30 domestic silkworms downloaded from Gen Bank database. Polymorphism analysis showed that mitochondrial COⅠ genes from 16 Chinese and 2 Japanese wild silkworms contain 65 and 10 SNPs respectively, while only 7 SNPs were found in COⅠ genes from 30 domestic silkworms. Compared with samples from Sichuan and Jiangsu regions,wild silkworms collected from Japan,Qingzhou（ Shandong Province,China） and Qinling-Daba mountain region have more SNPs in mitochondrial COⅠ gene.The COⅠsequences of 18 wild silkworms and 30 domestic silkworms had 25 haplotypes,a mong which 18 haplotypes were from wild silkworms and 7 haplotypes were from domestic silkworms. Cluster analysis of these sequences showed that the phylogenetic tree of 18 wild silkworm germplasm resources were partially related with their geographical origins.The wild silkworms from Sichuan and Jiangsu regions were clustered into separate clades,while the 5 samples from Qinling-Daba mountain region were clustered with samples from Qingzhou or Sichuan region. Compared with Japanese wild silkworm,Chinese wild silkworm has much closer relationship with domestic silkworm. Chinese wild silkworms collected from Hanyin County,Lan＇gao County,and Hanbin District of Ankang City,Shaanxi Province and from Qingzhou City of Shandong Province have the nearest genetic relationship with domestic silkworm. These results reveal that there is rich genetic diversity among the wild silkworms in Qinling-Daba mountain region. These data provide additional evidence to support that domestic silkworm originated from Chinese wild silkworm.