以足丝缺失或微细为育种目标的企鹅珍珠贝遗传育种体系构建

Winged pearl oyster, Pteria penguin, is a large pearl oyster that has the potential for the cultivation of large round pearls. However at present the problems of high mortality after implantation, low retention rate and low proportion of high-quality pearls have severely curbed the development of Pteria penguin industry. We think that the above problems might be attributed to relatively small size of the nucleus space caused by oyster’s strong byssus. Therefore the present study aims to breed byssusless winged oysters, to establish its breeding system and to enlarge the nuclues space through genetic improvement. First of all, the pearl oysters with byssus absence or minuteness will be used as the base population; secondly, nested matching design will be applied to establish the first generation family and the genetic parameters (heritability, etc.) and breeding values will be estimated will be estimated by means of REML and BLUP, as well. Thirdly, micrsatellite markers will be used to analyze the genetic lineage of families, their diversity and distance. Fourthly, the effects of family selection and pearl production will be tested. Finally, according to the genetic parameters and breeding values, the efficient and scientific breeding system of winged oyster will be established, their genetic development will be improved and the pearl oysters with byssus absence or minuteness fit for the production of large and high-quality round pearls will be developed. Fourthly, the genetic diversity of different families will be analyzed by micrsatellite markers. Fifthly, by means of truncation selection in the same intensity, we will compare the selection effect, realized heritability and genetic gain of progenies produced from different populations. Finally, the line which exhibits the largest genetic gain will be selected as a breeding system.

企鹅珍珠贝是一种大型珍珠贝类，具有培育大型圆形游离珍珠的潜力，但目前遇到插核后死亡率高、留核率低和优珠率低等的问题，严重地制约了养殖业的发展。本项目认为企鹅珍珠贝的足丝发达导致的插核核位偏小是其主要原因；因此，本项目拟以足丝缺失或微细为育种目标，构建企鹅珍珠贝的遗传育种体系，通过遗传改良扩大核位：首先，以企鹅珍珠贝群体中足丝缺失或微细的个体建立基础群体；第二，通过巢式交配设计建立第 1 代家系，分别应用限制性最大似然法（REML 法）和最佳线性无偏估计法（BLUP 法）分析足丝性状和生长性状的遗传参数（遗传力等）和估算育种值；第三，通过微卫星标记对家系进行谱系鉴定，分析各家系的遗传多样性和家系间的遗传距离；第四，家系选育的插核效果和育珠效果验证；最后，根据家系和个体各种遗传参数和育种值估算，构建企鹅珍珠贝育种体系，为培育出足丝缺失或微细的、用于生产大型珍珠的企鹅珍珠贝新品种奠定基础。

企鹅珍珠贝是一种大型珍珠贝类，具有培育大型圆形游离珍珠的潜力，但因它的足丝发达导致的插核核位偏小，无法插核育珠。本项目拟以足丝缺失或微细为育种目标，构建企鹅珍珠贝的育种体系，通过遗传改良扩大核位。由于企鹅珍珠贝体外受精无法成功，构建家系困难，我们在执行过程中，以群体选择方式构建育种体系，完成了基础群体（G0）建立，群体选择两代（G1和G2）、开展了插核育珠效果验证。初步成果：（1）足丝缺失或微细为育种目标的企鹅珍珠贝育种体系是可行的，随着群体选择的逐代选育，企鹅珍珠贝足丝根直径BD经过群体选择从第一代（G1）开始就显著下降，选择第二代（G2）下降更为明显；（2）通过企鹅珍珠贝育种体系（G2）与对照组插核育珠效果初步分析，选育群体G2的插核贝成活率比对照群体（BZ2）提高4.20%，虽无显著差异，但在留珠贝率上，选育群体G2的插核贝成活率比对照群体提高23.03%，差异显著，需要继续逐代选择，将能最终培育出培育大型优质珍珠的企鹅珍珠贝新品种；（3）通过企鹅珍珠贝育种体系群体与对照组群体遗传多样性的微卫星分子标记分析表明，通过两代选择，选育群体无论是平均等位基因数和等位基因丰度还是期望杂合度和观察杂合度数值均有下降，表明通过选择选育改变了子代的基因组合，导致基因杂合性和遗传多样性的逐代下降趋势，这也是选择在起作用的直接表现。总之，本项目完成了以足丝微细为目标构建企鹅珍珠贝的育种体系构建，但需要再继续4-5代选育工作。本项目为进一步探讨（1）企鹅珍珠贝的足丝结构与形态相关性、足丝生长与附着的关系以及（2）企鹅珍珠贝精子取自精巢无受精作用等问题，我们增加了部分其他双壳贝类精子激活因子等研究内容，取得了比较好的理论结果。本项目共发表7篇SCI收录论文，获得授权发明专利2项，编制1个国家标准，培养3位研究生（博士后、博士和硕士各1人），完成了研究任务，部分超额。