家蚕杂交分离系的AFLP分析初探

A PRELIMINARY AFLP ANALYSIS OF SEGREGATING OFFSPRINGS IN SILKWORM BOMBYX MORI CROSS COMBINATIONS

以日系家蚕品种"湘晖"和"872"为亲本进行杂交,从F2代分别向茧丝量高(A)、中(B)、低(C)3个方向进行定向选择。经过F2～F6共5代的同蛾区交配和选择,获得了茧丝量性状有显著差异的A,B,C共3个家系。以中系蚕品种芙蓉、菁松及其杂交后代为参照群体,对3个杂交分离系进行AFLP分析,获得了617个AFLP分子标记。结果显示:选择到F4代时,A,B,C各杂交分离系的AFLP分子标记表现出一定的差异,到F6代时,A,B,C各杂交分离系间的分子标记差异十分显著且稳定。利用UPGMA法进行聚类分析的结果也显示有很强的规律性,所有个体均按家系有规律地聚在一起。从分子水平证明家蚕同蛾区杂交后代系统选择到F6代即可获得遗传性稳定的不同杂交分离系。

Starting from the F2 generation, directional selection was made for high (A), middle (B) and low (C) cocoon silk amount in the offspring of the cross combination between the Japanese silkworm strains 'Xianghui' and '872'. By adelphogamy and selection in the 5 generations from F2 to F6, 3 lineages significantly different in cocoon silk amount were obtained. Their DNA polymorphisms were analyzed with AFLP, with the Chinese silkworm strains 'Furong' and 'Jingsong' and their cross offsprings as the control, and 617 AFLP molecular markers were obtained. The results showed that considerable differences appeared in the AFLP molecular markers among A, B and C lineages in F4 and such differences became significant and stabilized in F6. The dendrogram by UPGMA showed a strong regularity as well: the individuals were clustered according to their respective lineages. It is, therefore, verified that genetically stable lineages can be obtained in the F6 generation by adelphogamy combined with selection.Key words: silkworm (Bombyx mori); segregating strain; AFLP