猪15号染色体上影响背最长肌糖原含量和滴水损失的QTL解析

发布时间：2018-01-24 21:55

本文关键词： 猪肉质性状全基因组关联分析 QTL 精细定位候选基因　出处：《江西农业大学》2015年硕士论文　论文类型：学位论文

【摘要】：猪肉品质是猪的重要经济性状,提高猪肉品质是现代种猪选育工作的重要目标之一。然而肉质是一个综合性状且遗传力都偏低,传统育种难以得到好的改良效果,因此对猪肉质性状分子遗传机理的研究就显得十分必要。本实验屠宰并测定了共610头杜长大个体36h肌肉酸度(pH)、剩余糖原含量(RG)、滴水损失(drip loss)、红度(Minolta a*)、黄度(Minolta b*)、亮度(Minolta L*)、肉色(color score)、大理石纹(marbling)、水分(moisture content)等肉质性状表型并利用猪60K芯片进行了全基因组关联分析。结果共检测到17个显著性位点,其中3个SNP达到了基因组显著水平。同时在15号染色体上121 Mb处和134Mb处发现两个同时影响剩余糖原含量、滴水损失和肉色的多效性数量性状位点(QTL),在此命名为QTL_1和QTL_2。在QTL_1区域(129~135 Mb)内,笔者发现一个与RG强关联的SNP SS478944394(129.80 Mb,P=1.18×10~(-11))和一个与滴水损失及肉色强关联的SNP SS107833468(134.40 Mb,P10~(-5)),并推测已知的肉质性状主效基因PRKAG3(133.80 Mb)为其候选基因。为确定这一点,本研究在QTL_1区域内增加15个SNPs再做关联分析,结果在PRKAG3基因编码区内发现一个更强关联位点—rs42(133.80 Mb),该SNP与糖原含量(P=1.08×10~(-49))、滴水损失(P=1.95×10~(-12))、pH值(P=3.19×10~(-6))、L*值(P=1.54×10-9)、a*值(P=9.36×10~(-8))、b*值(P=7.28×10~(-13))等肉质性状的关联程度都达到了基因组显著性水平,且该位点解释了杜长大群体40.6%的糖原表型变异方差和8.6%的滴水损失表型变异方差。在QTL_2区域(120.78~122.78 Mb)内,SNP SS478943559(121.78 Mb)与剩余糖原含量(P=4.89×10~(-10))、滴水损失(P=2.39×10~(-5))、b*值(P=2.55×10~(-4))均显著相关,其周边有两个与糖代谢相关的强候选基因FASTKD2及MDH1B。为精细定位QTL_2,本研究在其区域内新增了45个SNP标记用于关联分析,结果显示最强关联位点仍为SS478943559,它处在一个23 kb单倍型框(r~20.8)内。对FASTKD2及MDH1B基因进行cDNA测序发现两个错义突变位点,其中FASTKD2中错义突变SNP g.6742GA的次等位基因频率为0.4,它与糖原含量、滴水损失关联分析所得P值分别为4.47×10~(-4)、5.37×10~(-4),因此可以作为种猪肉质选育的一个分子标记。而MDH1B中的SNP g.3597AG突变与糖原含量、滴水损失相关性不显著(P0.05),故排除此SNP作为因果突变的可能性。本研究加深了对杜长大商品猪肉质性状分子遗传机理的认识,同时为开发影响猪肉品质性状的分子标记并为最终鉴别影响糖原含量及滴水损失等相关肉质性状的因果基因或因果突变点奠定了一定的工作基础。
[Abstract]:Pork quality is an important economic trait of pigs, and improving pork quality is one of the important objectives of modern breeding pig breeding. However, meat quality is a comprehensive trait and the heritability is low. It is difficult to obtain good improvement effect in traditional breeding. Therefore, it is necessary to study the molecular genetic mechanism of pork quality traits. In this experiment, 610 individuals were slaughtered and their muscle acidity, pH value and residual glycogen content were measured for 36 h. The loss of drip water is the loss of drip, the degree of redness is minolta, the degree of yellowness is minolta, and the brightness is minolta. Meat color scoreen, marbling. The phenotypes of meat quality traits such as water moisture content were analyzed with porcine 60K microarray. A total of 17 significant loci were detected. Three of them reached the level of genomic significance. At the same time, at 121Mb and 134Mb on chromosome 15, two were found to affect the residual glycogen content at the same time. The quantitative trait loci of drip loss and meat color were named QTL_1 and QTL _ 2. In the QTL_1 region 129m ~ 135Mb). We find a SNP SS478944394(129.80 Mb strongly associated with RG. (1. 18 脳 10 ~ (-11)) and a SNP SS107833468(134.40 MbP10 ~ (-5), which is strongly associated with drip loss and meat color. The known major gene PRKAG3(133.80 Mb for meat quality traits is a candidate gene. In this study, 15 SNPs were added to the QTL_1 region to do the association analysis, and a stronger association locus -rs42 ~ (133.80 Mb) was found in the PRKAG3 gene coding region. The SNP and the content of glycogen were 1.08 脳 10 ~ (10) ~ (-49), and the loss of water was 1.95 脳 10 ~ (10) ~ (-12) ~ (?) pH value ~ (3. 19 脳 10 ~ (-6)). The L * value is 1.54 脳 10 ~ (-9) (P ~ (9.36) 脳 10 ~ (-8)). The correlation degree of meat quality traits, such as b* value (7.28 脳 10 ~ (-13)) and so on, reached the level of genomic significance. This locus explained the variance of phenotypic variation of glycogen in population 40.6% and the variation of phenotypic variation of drop water loss of 8.6% in Du-long population. Inner. SNP SS478943559(121.78 Mb) and the content of residual glycogen P 4. 89 脳 10 ~ (10) -10 ~ (10). There was a significant correlation between water drop loss and water loss (P = 2.39 脳 10 ~ (-1) ~ (-5) P ~ (2. 55) 脳 10 ~ (-4)). There are two strong candidate genes FASTKD2 and MDH1 B. which are closely related to glucose metabolism. In this study, 45 SNP markers were added to the region for association analysis. The results showed that the strongest correlation was still SS478943559. It was located in a 23kb haplotype frame rnrm20.8). FASTKD2 and MDH1B genes were sequenced by cDNA and two missense mutation sites were found. The secondary allele frequency of missense mutation SNP g.6742GA in FASTKD2 was 0.4, which was associated with glycogen content. The P values obtained from the correlation analysis of drip loss were 4.47 脳 10 ~ (-4) and 5.37 脳 10 ~ (-4) respectively. Therefore, it can be used as a molecular marker for breeding meat quality of pig, while the mutation of SNP g.3597AG in MDH1B has no significant correlation with glycogen content and drip loss (P0.05). Therefore, the possibility of this SNP as a causal mutation was excluded. This study deepened the understanding of the molecular genetic mechanism of meat quality traits in Du-long commercial pigs. At the same time, it lays a foundation for the development of molecular markers affecting pork quality traits and for the final identification of causal genes or causal mutation sites that affect glycogen content and drip loss.
【学位授予单位】：江西农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S828

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