生长相关分子标记在翘嘴鳜五代中的富集

为进一步了解人工选育对翘嘴鳜生长相关遗传标记的影响作用，研究以翘嘴鳜华康1号的5代选育群体为实验材料，对具有生长相关优势基因型的5个标记的6个位点进行扩增，通过直接测序和聚丙烯酰胺凝胶电泳两种方法分型后，统计其优势基因型个体数目在翘嘴鳜5代中的变化。结果显示，在5代群体中，2个单核苷酸多态性位点和4个微卫星位点优势基因型的数目的分布范围为0-4，从F1到F5代，这6个位点优势基因型的平均值分别为0.36、0.71、0.68、0.77和0.94，优势基因型的平均含量随选育世代的增加呈现递增趋势，从侧面反映了人工选育在一定程度上富集了优良基因。此外，对微卫星位点进行了遗传相似性和遗传距离分析，结果显示，随着选育的进行，后续世代与F1的遗传距离有明显的增大趋势，遗传相似性减小，这符合育种的客观规律。但相邻世代间的遗传距离则逐代减小，遗传相似性逐代增大，说明人工选育将遗传相似性较大的群体保留下来了，这种相似性表现在表型上包括生长快、体重大、体长增加等。F1到F5代处于中度遗传多样性的稳定状态，说明群体还存在选育空间。

PYRAMIDING OF GROWTH-RELATED MARKERS IN FIVE BREEDING GENERATIONS OF SINIPERCA CHUATSI BASILEWSKY

Gene pyramiding breeding is based on the effect of polygenic polymerization to change correlated character. In previous studies, growth-related markers were found in Siniperca chuatsi. Among them, five markers with six growth-favorable genotypes were selected, including two sites of single nucleotide polymorphism (SNP) located in GH gene and four sites of microsatellite (SSR):SC10, SC52, Sin135 and AP34-23. To get deeper insight into the effect of artificial breeding on growth-related markers identified in previous studies, we analyzed the number of favorable genotypes of these markers in five breeding generations of Siniperca chuatsi, Huakang No.1. By direct-sequencing and polyacrylamide gel electrophoresis, we found that the sum of two SNP favorable genotypes and four SSR favorable genotypes appeared pyramiding. The result showed that the number of total favorable genotypes ranges from 0 to 4 in the tested fishes. The average contents were 0.36, 0.71, 0.68, 0.77, 0.94 in F1, F2, F3, F4 and F5 generations, respectively, showing the number of favorable genotypes increased synchronously with the growth rate of the populations, which reflects that, artificial breeding has aggregated favorable genotypes in some degree. The SSR analysis showed that, when compared with F1, the genetic distances increased from F2 to F5 while the genetic similarity decreased, which observed objective law. When compared with its contiguous generation, the genetic distances decreased from F1 to F5 while the genetic similarity increased. The analysis of the genetic distances indicated that artificial breeding has conserved individuals of higher genetic similarity, which in performance have phenotypes of fast growth, heavier body weight or longer body length. The genetic diversity shows no large fluctuations, but a state of stability, which indicated further space for breeding.