甘肃地方肉牛群体瘦素基因(LEP)部分序列SNPs及其与胴体品质和肉质性状的相关性分析

本研究旨在寻找与肉牛胴体肉质等主要经济性状相关的分子标记,为甘肃地方肉牛新类群的选育提供分子遗传学理论依据。利用PCR-SSCP技术检测甘肃地方肉牛LEP基因第2外显子及第3内含子部分序列多态性,并分析其多态性与胴体品质和肉质性状的相关性。结果表明：LEP基因第2外显子存在AA和AB两种基因型,基因型频率分别为0.5217和0.4783;测序结果显示：在该基因1180 bp处存在一个C→T碱基突变,导致所编码的氨基酸由精氨酸变为半胱氨酸;该群体的多态信息含量处于0.25~0.5之间,属于中度多态（PIC〉0.25）;胴体和肉质性状相关性统计分析表明：该位点AA基因型与宰前活重、胴体重、净肉重、屠宰率和净肉率显著相关（P〈0.05）,AB基因型与失水率、板油重、大理石花纹等级和肉色等级显著相关（P〈0.05）,该位点SNP与胴体背膘厚、眼肌面积、蒸煮损失、剪切力、pH值差异不显著（P〉0.05）。初步判断该位点可作为影响胴体品质和肉质性状的遗传标记位点之一。

Single Nucleotide Polymorphisms in Leptin Gene (LEP) Associated With Carcass and Meat Quality Traits in Gansu Local Cattle

The objectives of this study were to find out the molecular markers related to carcass and meat quality economic traits, and provide the theoretical basis of molecular genetics for breeding the new groups of Gansu beef cattle. PCR-SSCP was used to detect the polymorphisms of exon 2 and intron 3 of LEP gene in Gansu local cattle and analyze its correlation with carcass and meat quality traits. The results showed that AA and AB genotypes were found in the LEP gene exon 2, the genotype frequencies were 0.5217 and 0.4783. Sequence analysis showed that there existed a mutation of C→T at 1180bp of LEPgene and resulted Arginine to Cysteine. The PIC was between 0.25-0.5, it was moderate polymorphism. Statistical analysis of carcass and meat quality traits showed that AA genotype has a significant effect on before slaughter live weight, carcass weight, meat weight, dressing percentage and meat percentage （P〈0.05）, AB genotype has a significant effect on pressing loss, leaf fat weight, marbling score and meat color （P〈0.05）, this site has no significant association with backfat thickness, loin eye area, cooking loss, shear force and pH （P〉0.05）. The preliminary judgment of this site can be considered as one of the genetic markers loci of carcass and meat quality traits.