Data Sheet 1_Integrating metabolomics and transcriptomics to analyze differences in muscle mass and flavor formation in Gayal and yellow cattle.docx

Beef flavor is affected by muscle metabolites and their related regulatory genes, and the molecular regulatory mechanisms vary among different beef breeds. To provide some new ways to improve meat quality and cattle breed improvement, 24-month-old Gayal (n = 8) and yellow cattle (n = 8) were selected for comparison in this study. The result revealed that the longissimus dorsi muscle fiber diameter, protein content and a-value of Gayal were significantly higher than that of yellow cattle, but the fat content was lower than that of yellow cattle. Furthermore, Gayal meat contained notably higher levels of polyunsaturated fatty acids (PUFA) and n-3PUFA than that of yellow cattle, and also had better levels of flavor amino acids (FAAs) and sweet amino acids (SAAs), which contribute to the flavor of beef. Through comprehensive analysis of transcriptomics and metabolomics, we detected a total of 109 markedly different metabolites (DEMs) and 1,677 differentially expressed genes (DEGs) in the pectoral muscles of the two breeds. Further analysis indicated that amino acid and lipid metabolism might be the key factors contributing to the differences in meat quality and flavor between Gayal and yellow cattle, involving metabolites such as L-2-aminobutyric acid, L-glutamic acid, L-glutamine, L-serine, betaine, pantothenic acid, and taurine. Through correlation analysis, we identified genes highly associated with flavor amino acids (GSTM3, GSTT2), muscle development (FGF10, EIF4EBP1, PPP2R2C), and lipid metabolism (CYP4A22, ACOX3, PLIN1, ADH6, CNDP1, LPAR3, BRCA1, ADIPOQ, FABP3) related essential regulatory genes and constructed a gene-metabolite interaction network for meat quality and flavor formation in Gayal. In summary, it was shown that significant differences in muscle metabolites between Gayal and yellow cattle, especially in amino acid and lipid metabolism, may be the major reason for the differences in quality and flavor between the two types of beef. This study provides a theoretical basis for further exploring the molecular regulatory mechanisms of the differences in beef quality and flavor between Gayal and yellow cattle, and provides a reference for the development and genetic breeding of high-quality cattle breeds.

牛肉风味受肌肉代谢物及其相关调控基因的影响，且不同肉牛品种的分子调控机制存在差异。为探寻改善肉质及肉牛品种选育的新路径，本研究选取8头24月龄的大额牛（Gayal）与8头黄牛开展对比实验。结果显示，大额牛的背最长肌肌纤维直径、蛋白质含量及a值均显著高于黄牛，而脂肪含量则低于黄牛。进一步研究发现，大额牛肉中的多不饱和脂肪酸（polyunsaturated fatty acids，PUFA）与n-3多不饱和脂肪酸（n-3PUFA）含量显著高于黄牛，同时其风味氨基酸（flavor amino acids，FAAs）与甜味氨基酸（sweet amino acids，SAAs）水平更优，这些物质均对牛肉风味的形成具有积极贡献。通过转录组学与代谢组学的联合分析，本研究在两个品种的胸肌中共检测到109种显著差异代谢物（markedly different metabolites，DEMs）与1677个差异表达基因（differentially expressed genes，DEGs）。进一步分析表明，氨基酸代谢与脂质代谢可能是导致大额牛与黄牛肉质及风味差异的关键因素，涉及的代谢物包括L-2-氨基丁酸、L-谷氨酸、L-谷氨酰胺、L-丝氨酸、甜菜碱、泛酸及牛磺酸等。通过相关性分析，本研究筛选出与风味氨基酸密切相关的核心调控基因（GSTM3、GSTT2）、参与肌肉发育的关键基因（FGF10、EIF4EBP1、PPP2R2C）以及参与脂质代谢的核心调控基因（CYP4A22、ACOX3、PLIN1、ADH6、CNDP1、LPAR3、BRCA1、ADIPOQ、FABP3），并构建了大额牛肉质与风味形成的基因-代谢物互作网络。综上，本研究发现大额牛与黄牛的肌肉代谢物存在显著差异，尤其是在氨基酸与脂质代谢通路层面的差异，可能是两类牛肉品质与风味产生分化的主要原因。本研究为进一步解析大额牛与黄牛肉质及风味差异的分子调控机制提供了理论基础，同时为优质肉牛品种的开发与遗传选育提供了参考依据。