长牡蛎(Crassostrea gigas)三个选育群体完全双列杂交后代生长性状分析

ANALYSIS OF GROWTH TRAIT OF PACIFIC OYSTER CRASSOSTREA GIGAS USING COMPLETE DIALLEL CROSS FROM THREE SELECTIVE BREEDING STRAINS

利用中国(C)、日本(J)和韩国(K)3个长牡蛎(Crassostrea gigas)第四(F4)代选育群体,采用完全双列杂交方式构建建立了3个自交群体、3个正交群体和3个反交群体。结果表明,各交配组合在180日龄、360日龄和450日龄生长优势差异显著(P<0.05);在不同生长阶段各组合的生长性能、一般配合力值、特殊配合力值和杂种优势效能值各不相同。杂交组合C♂K♀、J♂C♀和K♂J♀分别在180日龄、360日龄和450日龄表现出较大的生长优势,而自交组合K♂K♀在各个生长阶段均表现出生长劣势。中国F4代选育群体父母本一般配合力效应值均表现为非负值,而韩国F4代选育群体父母本一般配合力效应值均表现为非正值。杂交组合的特殊配合力效应值在不同生长阶段表现不一致,但与生长优势效能值基本相符。实验结果表明,多数杂交子代在生长性状上存在一定程度的杂种优势,可进行规模化商业推广应用;中国F4代选育群体作为杂交候选父母本时,具有高的可稳定遗传给子代的加性效应值。利用群体选育建立配套系,对不同选育群体进行杂交育种是培育长牡蛎优良新品系的有效方法。

Pacific oyster Crassostrea gigas is a major global aquaculture species, ranking first in production among all other aquaculture species. However, dressing percentage and flesh quality declined recent years, becoming a major problem in oyster culture industry. Genetic improvement of the species is urgent. In this study, inter strain hybridization was carried out using three strains(China, C; Japan J; and Korea, K) of C. gigas, and they were successively mass selected for four generation(F4) from three culture stocks of China, Japan and Korea. All 9 possible reciprocal strain crosses and pure strains were produced in a complete diallel cross design. The results show that growth performance is significant different in different mating groups on 180, 330, and 450 d(P<0.05, n=950). Growth performance, general combining ability(GCA), special combining ability(SCA), and heterosis potence are not identical in different growth stages. The best growth performance groups are C♂K♀, J♂C♀ and K♂J♀ on 180, 330, and 450 d, respectively. However, K♂K♀ shows growth disadvantage in every stage. The GCA is non-negative in both sire and dam of the C strain, while GCA of the K strain is non-positive. SCA is different in each stage, but is largely consistent with heterosis potence. Most of hybrid strains have growth heterosis in certain degrees, and can be applied commercially in large-scale production. The C strain has high and stable additive genetic value to hybrid offspring when used as candidate of parents. Therefore, to develop excellent Pacific oyster strain cross-breeding can be applied to establish different genetic breeding groups.