两种杂交石斑鱼子一代杂种优势的微卫星标记分析

SSR analysis of the heterosis in the two grouper hybrids

使用6对微卫星引物对两种杂交子一代(青龙斑和虎龙斑)及其亲本(斜带石斑鱼、棕点石斑鱼和鞍带石斑鱼)共5个群体进行微卫星分析,计算等位基因频率、有效等位基因数、基因杂合度、多态信息含量、相似指数和Nei氏遗传距离。结果显示,在5种石斑鱼中,棕点石斑鱼的平均有效等位基因数最大(6.849 3),最小的是鞍带石斑鱼(2.608 6)。6对微卫星引物在这5个群体中具有丰富的多态性,平均多态信息含量(PIC)分别为0.666 7、0.751 3、0.441 9、0.664 0、0.542 6。在平均观测杂合度(Ho)中,虎龙斑和青龙斑的最高均为0.940 0,鞍带石斑鱼的最低为0.508 3。遗传距离和遗传相似率结果显示,青龙斑和虎龙斑均与父本鞍带石斑鱼的亲缘关系较近。杂交子一代群体的等位基因基本来自父母本群体双方,可推断杂交子一代的遗传物质来自父母双方,属两性融合生殖,是真正意义上的杂交种。杂交后代的遗传变异水平明显增强,这是杂种优势得以形成的重要遗传物质基础。

The marine grouper species are considered high value food fish in Southeast Asia.Aimed to get some new types of grouper,we have successfully cross-bred three species of grouper.The hybrid grouper was produced by fertilising the eggs of the orange-spotted grouper（Epinephelus coioides）,tiger grouper（Epinephelus lanceolatus）with the sperm of the giant grouper（E.lanceolatus）through the in vitro fertilisation technique.The hybrids combine morphological features of the two parent species.And they are healthy and growing well in sea cages and the finding will be good news for the aquaculture industry.The genetic diversity among orange-spotted grouper,tiger grouper,giant grouper and their hybrid F1 generation population（Qinglong grouper and Hulong grouper）were tested by 6 microsatellite loci.The gene frequency,effective number of alleles（Ae）,observed heterozygosity（Ho）,polymorphism information contents（PIC）,genetic similarity and Nei＇s genetic distances（D）were studied.The results showed that,the E.fuscoguttatus showed the most alleles（6.849 3）,while the E.lanceolatus showed the least（2.608 6）.Rich polymorphisis was observed by the six primers,and the PIC values in the five populations were 0.666 7,0.751 3,0.441 9,0.664 0,0.542 6,respectively.And the F1 generations showed the highest observed heterozygosity（Ho）of 0.940 0,while the E.lanceolatus showed the lowest value of 0.508 3.The results of genetic distances and genetic similarity showed that both F1 generations had a close relationship with the male parent E.lanceolatus.The alleles of F1 generations were mostly generated from both of their parents,which mean that the genetic materials were inherited from parents.And the higher genetic diversity that existed in the two hybrids indicated potential heterosis.