陕西秦巴山区野桑蚕线粒体COⅠ序列的遗传多样性与系统进化分析

Genetic diversity and phylogenetic analysis of Qinba wild silkworm(Bombyx mandarina)based on mitochondrial DNA COⅠsequence

【目的】分析野桑蚕(Bombyx mandarina)的遗传多样性,为发掘和利用其基因资源提供参考。【方法】克隆8份秦巴野桑蚕线粒体COⅠ序列,联合GenBank中39份家蚕、17份野桑蚕COⅠ序列,用DnaSP 5.0软件统计核苷酸多样性和单倍型多样性,采用MEGA X软件构建系统发育树,Network 5.0软件构建单倍型中介网络。基于64份COⅠ序列进行聚类分析,分析遗传多样性和单倍型中介网络,探讨家蚕起源。【结果】克隆了8份秦巴野桑蚕线粒体COⅠ及其侧翼序列,序列长1531 bp,序列间存在18处核苷酸变异,定义了4个单倍型,8份秦巴野桑蚕与沈阳、青州等北方野桑蚕亲缘关系最近。系统发育树将64份线粒体COⅠ序列聚为4个类群,其中中国野桑蚕聚为2个类群,一是来自陕西、辽宁、山东等的北方野桑蚕,与家蚕遗传距离为0.00721;二是来自江苏、湖北、重庆等的南方野桑蚕,与家蚕遗传距离为0.01959;日本野桑蚕群体与家蚕遗传距离为0.03196。64份COⅠ序列共存在84处单碱基变异位点,定义了31种单倍型。单倍型中介网络图显示,31种家蚕、野桑蚕单倍型总体上可分为3个支系,其中单倍型H_22可能为家蚕祖先单倍型。【结论】秦巴山区野桑蚕与北方省份的野桑蚕亲缘关系最近,秦巴山区可能是家蚕驯化的起源地之一。

【Objective】This study investigated the genetic diversity of Bombyx mandarina to provide information for exploring and utilizing its gene resources.【Method】Eight wild silkworm from Qinba mountain region were sampled and mtDNA COⅠsequences were obtained and analyzed together with published COⅠsequences of 39 domestic silkworm and 17 wild silkworms in GenBank.The nucleotide diversity and haplotype diversity were analyzed using DnaSP 5.0,the phylogenetic tree were constructed using MEGA X,and the media-joining network was constructed with Network 5.0.The origination of Bombyx mori was also discussed based on cluster analysis,genetic diversity and media-joining network of 64 COⅠsequences of silkworms.【Result】This study obtained the COⅠsequences of 8 Qinba wild silkworm,and there were 4 unique haplotypes with 18 polymorphic sites among these sequences.Cluster analysis revealed that Qinba wild silkworm was closely related to wild silkworm from northern China.The Neighbor-Joining tree clustered the 64 COⅠsequences into four clades.Chinese Bombyx mandarina were well divided into two clades corresponding to wild silkworm derived from northern or southern China.The genetic distances between domestic silkworm and northern,southern and Japanese wild silkworm were 0.00721,0.01959 and 0.03196,respectively.There were 31 unique haplotypes with 84 polymorphic sites in 64 COⅠsequences.The network of haplotype revealed that the 31 haplotypes were divided into three lineages,and the H_22 might be the ancestor haplotype of domestic silkworm.【Conclusion】The genetic distance between Qinba and northern wild silkworm was closer than between others,and Qinba mountain regions might be one area of early domestication of Bombyx mori.