半滑舌鳎繁育群体的遗传组成及家系配组策略

摘要

用只读式电子芯片标识了291尾性腺发育较好的3龄半滑舌鳎Cynoglossus semilaevis繁育群体,其中雌性98尾,体质量(2 060±350)g;雄性193尾,体质量(500±140)g.利用20个微卫星标记分析繁育群体的遗传组成.结果表明,雌性群体(Ho=0.606)的观测杂合度显著高于雄性群体(Ho=0.548) (P＜0.05),有效等位基因数(Ne)、期望杂合度(He)和多态信息含量(PIC)差异不显著(P＞0.05),群体平均多态信息含量分别为0.654和0.616,雌、雄群体均处于高度多态水平(PIC＞0.5),表明半滑舌鳎群体遗传多样性较好,具备进一步繁殖、筛选优良品系的遗传潜力.用“基于亲本遗传背景的分子育种软件1.0”计算半滑舌鳎雌、雄个体间遗传距离在0.254～1.959之间,不同遗传距离范围的频率呈正态分布,其中个体间遗传距离在0.7～1.0之间的占51.82％,考虑到生产操作的便捷,设定亲本间最佳遗传距离阈值为0.7～1.0之内.根据统计结果,建立半滑舌鳎家系配组的策略为选择位于不同聚类分支、遗传距离在0.7～1.0之间、表型性状在均值以上的一对或多对亲本生产单家系或混合家系.根据此策略获得混合家系选育组,并以常规生产的苗种作为对照,经10个月养殖,选育组的平均体质量、体长与对照组差异显著,其中平均体质量高于对照组24.56％,平均体长高于对照组6.98％.%A total of 291 individuals (female 98,body weight (2 060 ± 350) g;male 193,body weight (500 ± 140) g) of 3-year-old half-smooth tongue sole (Cynoglossus semilaevis) broodstock with developed gonad was identified by read-only electronic chips.Twenty microsatellite markers were used to analyze the genetic composition of half-smooth tongue sole broodstock.The results showed that the observed heterozygosity was significantly higher in female population (Ho =0.606) than that in male population (Ho =0.548) (P ＜ 0.05),without significant differences in effective number of alleles (Ne),expected heterozygosity (He),and polymorphism information content (PIC).There was PIC of 0.654 in female population and 0.616 in male population,with high polymorphic level (PIC ＞ 0.5),indicating that the breeding population had rich genetic diversity and genetic potential for further breeding selection.The software Molecular Breeding Based on Genetic Background (Vision 1.0) revealed that the individuals' genetic distances were varied from 0.254 to 1.959 in the breeding population between male and female.The individuals with individuals' genetic distances from 0.7 to 1.0 accounting for 51.82％,showed normal frequency distribution of genetic distances.Therefore,individual genetic distances between 0.7 and 1.0 were considered as the threshold for the convenience of factory production of half-smooth tongue sole.The findings indicate that a pair or more parents with phenotypic traits value of over the means,on the different clustering brunches with genetic distances between 0.7 and 1.0,should be chosen in strategy of family mating groups in breeding population of half-smooth tongue sole for industrial production.The breeding group was obtained by the hybrid family according to the above strategy,and the conventional seedlings were as control.The breeding group was 24.56％ heavier and 6.98％ longer than the control after reared 10 months.