伊犁马MyoG基因外显子1多态性与肉质性状及肌纤维性状关联分析

为寻找伊犁马肉质性能的分子标记，试验以38匹伊犁马为材料，测定肉质性状（失水率、熟肉率、剪切力）和肌纤维性状（肌纤维横截面积、肌纤维直径、肌纤维密度），利用PCR直接测序法检测肌细胞生成素（meyogenin，MyoG）基因外显子1在伊犁马群体中的多态性，并对MyoG基因SNPs不同基因型与肉质、肌纤维性状进行关联分析。结果表明，MyoG基因外显子1检测出5个突变位点，分别为SNP1（g.31187343 A>C）、SNP2（g.31187333 G>A）、SNP3（g.31187132 C>T）、SNP4（g.31187105 C>G）和SNP5（g.31187099 C>T），其中SNP1为错义突变，碱基A突变为C使得氨基酸由苏氨酸突变为脯氨酸，其他位点均为无义突变。SNP3和SNP4为中度多态位点，SNP1和SNP2为低度多态位点，这4个位点均处于Hardy-Weinberg平衡状态。MyoG基因外显子1中SNP1和SNP4不同基因型个体失水率、熟肉率、肌纤维横截面积、肌纤维直径、肌纤维密度差异显著（P<0.05）；SNP3不同基因型个体熟肉率、肌纤维横截面积、肌纤维密度差异显著（P<0.05）；SNP2不同基因型个体各指标差异均不显著（P>0.05）。综上，伊犁马MyoG基因外显子1检测到5个多态位点，其中SNP1（g.31187343 A>C）、SNP3（g.31187132 C>T）和SNP4（g.31187105 C>G）位点不同基因型对肉质及肌纤维性状有显著影响，这些位点可作为伊犁马肉质性能潜在分子标记。

Correlation Analysis Between Polymorphism of MyoG Gene Exon 1 With Meat Quality Traits and Muscle Fiber Traits in Yili Horse

In order to find molecular markers for meat quality of Yili horses,38 Yili horses were used to determine meat quality traits and muscle fiber traits (including water loss rate,cooked meat rate,shear force,muscle fiber cross-sectional area,muscle fiber diameter and muscle fiber density).The polymorphism of myogenin (MyoG) gene exon 1 in Yili horse population was detected by PCR direct sequencing,and the relationship between different genotypes of MyoG gene SNPs and meat quality,muscle fiber traits were analyzed.The results showed that five SNPs were detected in exon 1 of MyoG gene,including SNP1 (g.31187343 A>C),SNP2 (g.31187333 G>A),SNP3 (g.31187132 C>T),SNP4 (g.31187105 C>G) and SNP5 (g.31187099 C>T).The SNP1 was found to be a missense mutation,and the mutation of base A to C occurs,which maked the amino acid mutation from threonine to proline.The other sites were found to be nonsense mutations.SNP3 and SNP4 were found to be moderately polymorphic,while SNP1 and SNP2 were low polymorphic,the four SNPs were in Hardy-Weinberg equilibrium.Association analysis showed that:SNP1 and SNP4 genotypes in exon 1 of MyoG gene were significantly associated with water loss rate,cooked meat rate,muscle fiber cross-sectional area,muscle fiber diameter and muscle fiber density (P<0.05).SNP3 genotypes were significantly associated with cooked meat rate,muscle fiber cross-sectional area and muscle fiber density (P<0.05).There was no significant correlation between SNP2 genotypes and each index (P>0.05).In conclusion,five SNPs were detected in exon 1 of MyoG gene in Yili horse,among which SNP1 (g.31187343 A>C),SNP3 (g.31187132 C>T) and SNP4 (g.31187105 C>G) had significant effects on meat quality and muscle fiber traits.These SNPs might become molecular markers of meat quality in Yili horse.