VRTN基因在2个长白种猪核心群的分子标记辅助选择研究

VRTN基因是影响猪胸椎数的主效基因，其优势等位基因（Q）比劣势等位基因（q）具有多1对肋骨的效应。本文旨在探索VRTN基因在2个长白种猪群中的分子标记辅助选择方法，以期提高配套肉猪的肋骨数。采用PCR方法检测影响胸椎数（肋骨对数）的VRTN基因在温氏集团420头商品肉猪以及2个专门化长白种猪（913头W51系长白，240头W52系长白）群体中的分布情况。通过商品肉猪的效应分析，验证了在终端商品肉猪中QQ型较qq型猪只多近1对肋骨，说明分子标记辅助选择进行基因改良是可行的。试验结果显示：VRTN基因在2个长白群体中的等位基因频率相差不大，有利等位基因频率分别为0.844和0.905。通过基因型与选育性状表型的相关分析，发现W51系长白猪中，优势基因型猪只体长优势明显，对其他选育性状无影响。W52系中，优势等位基因与达100 kg/115 kg日龄估计育种值呈显著负相关，与其他性状无显著相关性。VRTN优势等位基因型的效应与选育目标一致，2个品系均可开展分子标记辅助选择。结合现场实践育种，W51通过种群更新优化，经过半年就实现了优势等位基因频率100%的完全纯化。W52在扩群的同时，经过2年达到基本纯化。

Molecular maker-assisted selection of VRTN gene in two Landrace swine nucleus herds

VRTN gene is the major gene affecting the number of thoracic vertebra in pigs, which QQ genotype (ins/ins) individuals have one double ribs more than qq (-/-) genotype ones. The molecular marker-assisted selection method of VRTN gene in two landrace pig populations was explored to improve the number of ribs of mating pigs. In the study, PCR were used to detect the distribution of VRTN genes in 420 commercial pigs of Wens Group and 2 specialized landrace pigs (913 W51 Landrace and 240 W52 Landrace),which affected thoracic vertebra number (rib number). It is verified that QQ type had nearly one pair of ribs more than qq type in Wens terminal pigs by effect analysis of commercial pork pigs, which indicated that gene improvement could be carried out through molecular marker-assisted selection. The allele frequencies of VRTN gene in the W51, W52 Landrace populations were not significantly different, and the favorable allele frequencies were 0.844 and 0.905 respectively. Through the correlation analysis between genotype and phenotypes of breeding traits, it was found that among W51 Landrace pigs, the dominant genotype had obvious body length advantage and had no influence on other breeding traits. In W52 line, the dominant allele had a significant negative correlation with the estimated breeding value of age at 100 kg/115 kg body weight, but had no significant correlation with other traits. The effect of VRTN dominant allele type was consistent with the breeding goal. Molecular marker-assisted selection could be carried out for W51 and W52 lines both. Combining with field practice breeding, W51 achieved 100% complete purification of dominant allele frequency after half a year through population renewal and optimization. W52 was basically purified after 2 years while expanding its population.