Leal-Gutiérrez Joel D, Rezende Fernanda M, Reecy James M, Kramer Luke M, Peñagaricano Francisco, Mateescu Raluca G
Department of Animal Sciences, University of Florida, Gainesville, FL, United States.
Faculdade de Medicina Veterinária, Universidade Federal de Uberlândia, Uberlândia, Brazil.
Front Genet. 2020 Sep 4;11:538640. doi: 10.3389/fgene.2020.538640. eCollection 2020.
Tenderness is a major quality attribute for fresh beef steaks in the United States, and meat quality traits in general are suitable candidates for genomic research. The objectives of the present analysis were to (1) perform genome-wide association (GWA) analysis for marbling, Warner-Bratzler shear force (WBSF), tenderness, and connective tissue using whole-genome data in an Angus population, (2) identify enriched pathways in each GWA analysis; (3) construct a protein-protein interaction network using the associated genes and (4) perform a μ-calpain proteolysis assessment for associated structural proteins. An Angus-sired population of 2,285 individuals was assessed. Animals were transported to a commercial packing plant and harvested at an average age of 457 ± 46 days. After 48 h postmortem, marbling was recorded by graders' visual appraisal. Two 2.54-cm steaks were sampled from each muscle for recording of WBSF, and tenderness, and connective tissue by a sensory panel. The relevance of additive effects on marbling, WBSF, tenderness, and connective tissue was evaluated on a genome-wide scale using a two-step mixed model-based approach in single-trait analysis. A tissue-restricted gene enrichment was performed for each GWA where all polymorphisms with an association -value lower than 1 × 10 were included. The genes identified as associated were included in a protein-protein interaction network and a candidate structural protein assessment of proteolysis analyses. A total of 1,867, 3,181, 3,926, and 3,678 polymorphisms were significantly associated with marbling, WBSF, tenderness, and connective tissue, respectively. The associate region on BTA29 (36,432,655-44,313,046 bp) harbors 13 highly significant markers for meat quality traits. Enrichment for the GO term GO:0005634 (Nucleus), which includes transcription factors, was evident. The final protein-protein network included 431 interations between 349 genes. The 42 most important genes based on significance that encode structural proteins were included in a proteolysis analysis, and 81% of these proteins were potential μ-Calpain substrates. Overall, this comprehensive study unraveled genetic variants, genes and mechanisms of action responsible for the variation in meat quality traits. Our findings can provide opportunities for improving meat quality in beef cattle via marker-assisted selection.
在美国，嫩度是新鲜牛排的一项主要品质属性，总体而言，肉质性状是基因组研究的合适对象。本分析的目的是：（1）利用安格斯牛群体的全基因组数据，对大理石花纹、沃纳-布拉茨勒剪切力（WBSF）、嫩度和结缔组织进行全基因组关联（GWA）分析；（2）在每次GWA分析中确定富集途径；（3）利用相关基因构建蛋白质-蛋白质相互作用网络；（4）对相关结构蛋白进行μ-钙蛋白酶解评估。评估了一个由2285个个体组成的安格斯父系群体。动物被运至一家商业屠宰厂，平均在457±46日龄时屠宰。宰后48小时，由分级员通过视觉评估记录大理石花纹。从每块肌肉中采集两块2.54厘米厚的牛排，由感官评定小组记录WBSF、嫩度和结缔组织情况。在单性状分析中，采用基于两步混合模型的方法在全基因组范围内评估加性效应与大理石花纹、WBSF、嫩度和结缔组织的相关性。对每次GWA进行组织特异性基因富集分析，纳入所有关联值低于1×10的多态性。将鉴定出的相关基因纳入蛋白质-蛋白质相互作用网络，并进行蛋白水解分析的候选结构蛋白评估。分别有1867、3181、3926和3678个多态性与大理石花纹、WBSF、嫩度和结缔组织显著相关。BTA29上的关联区域（36,432,655 - 44,313,046 bp）含有13个与肉质性状高度显著相关的标记。包括转录因子在内的GO术语GO:0005634（细胞核）的富集很明显。最终的蛋白质-蛋白质网络包括349个基因之间的431个相互作用。基于重要性的42个编码结构蛋白的最重要基因被纳入蛋白水解分析，其中81%的蛋白是潜在的μ-钙蛋白酶底物。总体而言，这项综合研究揭示了导致肉质性状变异的遗传变异、基因和作用机制。我们的研究结果可为通过标记辅助选择改善肉牛的肉质提供机会。
