Table_4_Comparative Transcriptome Analysis Reveals the Mechanism Associated With Dynamic Changes in Meat Quality of the Longissimus Thoracis Muscle in Tibetan Sheep at Different Growth Stages.XLSX

Tibetan sheep are mainly distributed in the Qinghai–Tibet Plateau. Its meat is not only essential for the local people but also preferred by the non-inhabitant of this plateau also. To investigate the salient development features and molecular mechanism of the meat difference of LT muscle caused by different growth stages in Tibetan sheep, the carcass performance, meat quality, and comparative transcriptome analysis were performed for investigating the potential molecular mechanism of the meat quality difference of the LT muscle caused by four growth stages [4-months old (4 months), 1.5-years old (1.5 years), 3.5-years old (3.5 years), and 6-years old (6 years)] in the Tibetan sheep. The shear force increased with the increase of age (p < 0.05) while the intramuscular fat (IMF) was the highest at 1.5 y. The AMPK signaling pathway was significantly enriched in the four comparative groups. The weighted gene co-expression network analysis (WGCNA) results showed that the hub genes P4HA2, FBXL4, and PPARA were identified to regulate the meat quality. In summary, 1.5 years was found to be the most suitable slaughter age of the Tibetan sheep which ensured better meat tenderness and higher IMF content. Moreover, the genes LIPE, LEP, ADIPOQ, SCD, and FASN may regulate the transformation of the muscle fiber types through the AMPK signaling pathway, further affecting the meat quality.

藏羊（Tibetan sheep）主要分布于青藏高原。其肉质不仅是当地居民的必需食材，亦深受高原非本地居民的喜爱。为探究不同生长阶段藏羊背最长肌（longissimus thoracis, LT）肉质差异的显著发育特征与分子机制，本研究针对藏羊四个生长阶段[4月龄（4个月）、1.5岁龄（1.5年）、3.5岁龄（3.5年）及6岁龄（6年）]的屠体性能、肉质性状开展研究，并进行比较转录组分析，以揭示其背最长肌肉质差异的潜在分子机制。剪切力随月龄增长显著升高（p < 0.05），而肌内脂肪（intramuscular fat, IMF）含量在1.5岁龄时达到峰值。AMPK信号通路在四组比较分析中均显著富集。加权基因共表达网络分析（weighted gene co-expression network analysis, WGCNA）结果显示，筛选得到的核心基因P4HA2、FBXL4及PPARA可调控肉质性状。综上，1.5岁龄为藏羊的最佳屠宰年龄，此时其肉质嫩度更佳且肌内脂肪含量更高。此外，LIPE、LEP、ADIPOQ、SCD及FASN等基因可通过AMPK信号通路调控肌纤维类型转化，进而影响肉质性状。