杜洛克猪生长与免疫力性状遗传相关机制研究

Approximately 20,000 pigs are imported into our country from abroad every year. The phenomenon that worse and worse production performance, high mortality and the changes of rank of breeding values is often observed due to the poor environment inside or outside the farm and complex vaccination program. In order to ascertain the reason, the present project intends to undertake the following work at the genetic molecular level: (1)exploring the genetic mechanism of pleiotropy, genetic linkage, and gene interaction of growth and immune capacity related traits by illustrating the relationship between growth QTLs and immune capacity QTLs; (2)analyzing the influence of breeding over immune capacity under the condition of "clean environment+simple vaccination programs" by using the genome-wide genetic markers(SNP, InDel, CNV, etc.) detected by the method of genome reducing and sequencing (GGRS); (3)studying the interactions between genetic and environment effects and genetic architecture of the growth and immune capacity related traits under different environmental conditions and genetic vaccination program through the measurements of growth and immune parameters, genome reducing and sequencing(GGRS), and GWAS; (4) verifying the effects of growth and immune capacity related genes at the cellular level; (5) establishing a reference population and corresponding database under internal environment conditions and vaccination programs. Obviously, the research work will help us understand the pig imports correctly, explore the mechanisms of growth and immune capacity related traits under different environmental conditions, and lay the necessary foundation for our own breeding.

我国每年引进一两万头种猪。但因猪场内外环境较差、免疫程序复杂，引进品种的猪往往生产性能每况愈下、死亡率高、育种值的排序发生变化。为了探明其中原因，本项目拟在分子水平上开展下列工作：（1）分析已知生长QTL与免疫力QTL间的关系，借以初步探明二者"一因多效、基因连锁、基因互作"等遗传相关的基础与机制；（2）运用简化基因组测序数据通过全基因组尤其是免疫相关SNP、InDel、CNV等的比较，分析"清洁环境+简单免疫"条件下育种对免疫力的影响；（3）通过生长与免疫指标测定、简化基因组测序及进一步的GWAS，分析环境与遗传的互作及不同环境与免疫程序条件下生长与免疫力的遗传相关机制；（4）在细胞水平上验证生长与免疫力相关基因的效应；（5）建立国内环境与免疫程序条件下GS参考群及数据库。通过这些工作，将使我们正确认识引种，探明不同环境与免疫条件下生长与免疫力的相关机制，为我国自主育种奠定必要的基础。

我国每年引进一两万头种猪。但因猪场内外环境较差、免疫程序复杂，引进品种的猪往往生产性能每况愈下、死亡率高、育种值的排序发生变化。为了探明其中原因，本项目在分子水平上开展了下列工作：①我们首先注释了生长与免疫性状之间QTL交集区段，定位了猪基因组上的生长与免疫间的一因多效基因与基因集。同时，基于人类GWAS的摘要统计量，我们发现生长与免疫的遗传相关主要为负相关。而利用GWAS结果在猪上的同源基因，我们进一步扩充了猪基因组上的各类多效性基因，最终确定了猪基因组上生长与免疫之间482一因多效基因、8个一因多效连锁区间以及29条一因多效通路。②对杜洛克猪群体在生长性状上利用美国环境的信息与中国环境的信息所估计的育种值进行对比，发现在生长速度性状上两组育种值相关系数为-0.3，即发生了遗传与环境互作。我国猪场的免疫程序复杂，这一结果的出现提示我们必须更新引种以及后续育种策略。③对起源于同一个群体而处于中、美两个环境下的杜洛克猪群体进行了基因组对比分析。结果发现二者呈现了显著分化，分化信号与免疫和肉质性状相关。而且，在免疫相关的信号上，处于我国环境下的群体更加靠近有更好免疫力的太湖猪群体。同时，我们发现中西方猪群体之间最显著的分化信号落生长与免疫的一因多效基因IGF1R内部。而我国地方猪群体近期的选择信号在生长与免疫一因多效性基因集中达到富集，可见基因组上的多效性在中西方猪种种质特性形成中发挥了作用。④同时，我们利用一组丹麦奶牛的繁殖数据，验证了基于遗传与环境互作的基因组选择模型的应用可能性，并对我国的杜洛克猪群体利用SNP芯片、简化基因组测序、重测序进行了基因型检测，为后续开展我国环境下的杜洛克猪群体的全基因组选择奠定了基础。