为检测家蚕(Bombyx mori)地方品种间的遗传差异,分析其遗传多样性和系统分化模式,为家蚕的品种鉴定和杂交育种亲本选择提供分子依据,本文对72个家蚕地方品种的淀粉酶基因(Bmamy2)片段进行测序,采用DNA序列分析技术探究了家蚕地方品种在核苷酸序列水平上的遗传差异及其系统分化特征。结果显示,家蚕地方品种在Bmamy2基因变异丰富,碱基突变率为5.6–8.2%,单倍型多样度为0.8294,核苷酸多样度为0.0236±0.00122,表明Bmamy2是一个具有丰富序列多样性的标记基因,能够较好地区分家蚕地方品种间的遗传多样性。系统发育分析、分子方差分析和Network分析等多种分析方法均检测到家蚕地方品种不按地理系统或生态类型聚类,各聚类种群均由来自不同地理系统或生态类型的品种构成,而来自同一地理系统或生态类型的品种则分别归属于不同的聚类种群。推测在家蚕的进化过程中并没有形成按地理系统或生态类型归类的分化格局,家蚕可能具有多种化性混合驯化起源的遗传背景和系统分化特征。
In order to explore the genetic diversity and systematic differentiation pattern among silkworm varieties, aiming to guide hybridization breeding, we sequenced a total of 72 Bmamy2 gene fragments from local silkworm varieties. The analysis of nucleotide sequence diversity and systematic differentiation indicated that there was rich genovariation in the sequencing region of Bmamy2 gene, and the base mutation rate is 5.6–8.2%, the haplotype diversity is 0.8294, and the nucleotide diversity is 0.0236±0.00122, suggesting Bmamy2 being a better marking gene with rich nucleotide sequence diversity, based on which the genetic diversity among different local silkworm varieties can be identified. The same heredity population structure is proclaimed by several analysis methods that every clade consisting of varieties from different geosystems and ecological types, while the varieties from the same geosystem and ecotype belong to different clades in the phylogeny. There is no population structure pattern that different varieties claded together according to geosystem or ecotype. It can be speculated that the silkworm origins from mixture of kinds of several voltinism mulberry silkworm, Bombyx mandarina, while the domestication events took place in several regions, from which the domesticated mulberry silkworms are all devoting to the domesticated silkworm population of today.