马氏珠母贝选系F_4遗传结构和亲缘关系建分析

G enetic Diversity and Sibling Relationship Reconstruction of Pearl Oyster Pinctada martensii by Microsatellite Markers

为了有效避免因近交引起性状退化,本实验利用微卫星标记分析了选系F4的遗传结构,并估计了其有效亲本的数量。2010年9月,从快速生长系F3选择亲本进行子代繁殖,雌雄亲本数量分别为42和38个,人工解剖授精,按照常规技术进行幼体培育和海区养殖。2011年6月,从选系F4随机选取90个个体,利用45对微卫星引物进行遗传结构分析和有效亲本数量的推断。结果表明:45个微卫星位点共检测到186个等位基因,每个位点的等位基因数在2～9之间,平均每个位点有4.13个等位基因。平均观察杂合度为0.543;平均期望杂合度为0.542;平均Shannon多样性指数为1.012;平均PIC值为0.491。根据基因频率的似然率算法成功的推断出该群体含有30个全同胞家系,用于繁殖选系F4有效亲本数量为60个,有75%的亲本参与了繁殖。世代之间近交系数增量△F=0.83%,F4代群体的近交系数F=3.27%。本研究结果表明:(1)该选系F4具有较高的遗传变异;(2)利用微卫星标记能有效推算选系的有效亲本数量,同时为构建继代群体提供技术支持。

The present studies reported genetic diversity by using microsateUite marker system with an aim to and parental size of the fourth generation selected line avoid depression on traits of the line. The line was developed by sampling parental breeders with superior growth rate from the third generation selected line in September of 2010. The female and male breeder numbers were 42 and 38, respectively. In June of 2011, 90 individuals were randomly sampled from the selected line and subjected to the experiment where genetic diversity and full-sibs relationships were analyzed by using forty-five microsatellite loci. A total of 186 alleles were detected and the number of the alleles at each locus ranged from 2 to 9 with a mean of 4.13. The average observed heterozygosity, average expected heterozygosity, Shannon diversity index and PIC values were 0.543, 0.542, 1.012 and 0.491, respectively. 30 full-sibs families were obtained on the basis of likelihood ratio algorithm of gene frequency. 75% breeders were contributed to progeny. Inbreeding coefficient increment was 0.83% between the third and fourth generation selected lines. The inbreeding coefficient of the fourth generation selected line was 3.27%. These results showed that the selected group had a high level of genetic diversity and microsatellite marker system was effective to estimate parental size.