尼罗罗非鱼与萨罗罗非鱼回交子代遗传变异的微卫星分析

Microsatellite marker analysis of genetic variation in the backcross progenies from Oreochromis niloticus and Sarotherodon melanotheron

用6对微卫星引物对尼罗罗非鱼、萨罗罗非鱼及其正反杂交鱼的正反回交子代共6种遗传型（genotype）罗非鱼进行了遗传变异分析，探讨回交的遗传效应。结果表明：（1）6对引物均有较好的多态性，可用于这6种罗非鱼的遗传变异分析；（2）6个微卫星位点在6种鱼中的平均杂合度为0．562～0．731，其中正回交鱼萨尼×尼罗最高（0．731），原始亲本尼罗最低（0．562）；多态信息含量为0．510～0．685，也是萨尼×尼罗最高（0．685），尼罗（0．510）最低；有效等位基因范围是2．71～3．85，也是萨尼×尼罗（3．85）最高，原始亲本尼罗最低（2．71）。（3）两种反回交子代的Nei’s遗传距离都与亲本尼罗接近，采用UPGMA和NJ法构建的聚类图表明，回交种与原始母本尼罗罗非鱼为一组，原始父本萨罗罗非鱼为另一组。萨尼×尼罗群体内遗传变异水平最高，是最有育种潜力的回交种；母本尼罗对回交子代的遗传影响大于父本萨罗，回交子代表现了一定的母本效应。

6 pairs of microsatellite primers were used to study genetic variation of Oreochromis niloticus, Sarotherodon melanotheron and their reciprocal backcross progenies. The results indicated ： （ 1 ） Six pairs of primers showed rich polymorphic, which can be used as good genetic markers for the genetic variation study of these tilapias. （ 2 ） The average heterozygosity （ H ） was 0. 562 - 0. 731, the highest value was in （ S. melanotheron ♀ × O. niloticus ♂ ） ♀ × O. niloticus ♂ （0. 6727）, the lowest existed in O. niloticus. The average polymorphism information content （PIC） was 0. 510 -0. 685, the highest existed in （S. melanotheron ♀ × O. niloticus ♂ ） ♀ × O. niloticus （0. 685 ） and the lowest was in the O. niloticus （0.51 ）. The effective numbers of alleles was 2.71 - 3.85 , the highest value existed in （ S. melanotheron ♀ × O. niloticus ♂ ） 9 × O. niloticus ♂ （ 3. 85 ）, the lowest existed in O. niloticus （ 2. 71 ）. （ 3 ） Both negative backcross progenies have the closest genetic distance with O. niloticus; UPGMA and NJ trees showed that the backcross progenies and O. niloticus were grouped together, S. melanotheron comprised the other clade. The result that the highest genetic diversity existed in （ S. melanotheron ♀ × O. niloticus ♂ ） ♀ × O. niloticus ♂ indicated this cross has the largest potential for further breeding; The maternal line of O. niloticus has made more genetic impact on the backcross progenies than the paternal line of S. melanotheron. The backcross progenies showed obvious maternal effect.