壳白长牡蛎基因型与环境互作(G×E)效应分析

Genotype by environment (G×E) interaction for growth and shell color traits in the white-shell strain of Pacific oyster (Crassostrea gigas)

摘要:

为探索壳白长牡蛎品系的壳色性状和生长性状的基因型与环境互作（G×E）效应，利用巢氏设计构建全同胞家系，每个家系分成两组分别在乳山和荣成海域进行养殖。利用线性混合模型和REML法分析11月龄壳白长牡蛎生长性状和壳色性状的遗传力及G×E效应。采用最佳线性无偏预测法（BLUP法）估计壳高和L*两个性状的育种值，并通过加权获得综合育种值来筛选优良家系。结果显示，乳山组和荣成组的壳白长牡蛎生长和壳色性状的遗传力不同，分别为（0.14±0.08）~（0.62±0.18）和（0.01±0.03）~（0.78±0.19），可能存在尺度效应。以不同环境为固定效应，综合两个环境计算出的生长和壳色性状的遗传力为（0.02±0.02）~（0.51±0.09），然而由于部分全同胞家系缺失和模型不收敛的原因，估计模型中未包括母本/共同环境效应和显性效应，上述遗传力估计值偏高。本研究中生长和壳色性状在两个环境间的遗传相关为（-0.47±0.40）~（0.75±0.18），均小于0.8，表明壳白长牡蛎品系的生长和壳色性状都具有明显的重排效应，壳白长牡蛎品系其选育需要针对不同的养殖环境培育不同适应性的选育家系。综合育种值排名前20的个体其家系来源比例表明，家系G1和G21对于乳山海域表现出特殊的适应性，而家系G4、G22和G5对荣成海域环境具有特适性，家系G2则对两个环境具有普适性。研究为壳白长牡蛎品系的良种选育提供了重要的参考依据。

关键词:长牡蛎;壳白;生长性状;壳色性状;基因型与环境互作(G×E)效应;育种值

Abstract:

The purpose of the present study is to reveal the genotype by environment (G×E) interactions on growth and shell color traits in the white-shell strain of Pacific oyster (Crassostrea gigas). The specimens of the white shell strain of C. gigas under six-generation of selection as parents were used to construct full-sib families following the method of nested design. All families were divided into two batches and grown in two environments, Rushan and Rongcheng. Linear mixed model and REML method based on an animal model were applied to estimate genetic parameters of white shell C. gigas at the age of 11 months. The best linear unbaised prediction (BLUP) method was used to estimate breeding values for shell height and L*, and superior families were selected based on comprehensive estimated breeding values. The results showed that heritabilities for growth and shell color traits in Rushan ranged from 0.14±0.08 to 0.62±0.18, while these were different in Rongcheng, varying from 0.01±0.03 to 0.78±0.19, which indicated that G×E interactions might be present as scale effects. After integrating the data in two different environments, heritabilities for growth and shell color traits ranged from 0.02±0.02 to 0.51±0.09. However, the estimates of heritabilities might be over-estimated because maternal/common environmental effects and dominance effects were included in the estimation model due to absence of some families and convergence problem. Genetic correlations for all growth and shell color traits between two environments, ranging from -0.47±0.40 to 0.75±0.18, were less than 0.8. This suggested that G×E interactions in the form of re-ranking of families across environments was apparent. It will be necessary to select lines that are suited to particular sites. The top 20 offspring in the rank of comprehensive estimated breeding values derived from different families in two different environments, indicating that the different families performed differently across the different rearing sites. The families G1 and G21 performed better in Rushan area, while the G4, G22 and G5 were most excellent families in Rongcheng area, and familiy G2 had high adaptability to both sites. The information obtained in this study will benefit genetic improvement of the white shell strain of C. gigas.

Key words:Crassostrea gigas;white-shell;growth traits;shell color traits;genotype by environment (G×E) interaction;breeding value