CKMT2 Promotes Breast Muscle Growth in Qiangying Ducks via Enhancing Myoblast Proliferation and Differentiation

The duck meat industry is economically vital in animal husbandry; however, the genetic mechanisms governing skeletal muscle development and muscle yield remain incompletely understood. In this study, RNA sequencing (RNA-seq) was used to identify differentially expressed genes (DEGs) in breast muscle tissues between high and low breast muscle weight (BMW) groups of Qiangying ducks. A candidate gene, CKMT2 (mitochondrial creatine kinase 2), was subsequently validated at the cellular and individual levels. RNA-seq analysis identified 540 DEGs, including 411 upregulated and 129 downregulated genes. GO and KEGG enrichment analyses revealed enrichment in fatty acid metabolism, fibrinolysis, and PPAR signaling pathways-processes closely linked to energy homeostasis and muscle growth. Functional validation demonstrated that CKMT2 overexpression significantly promoted myoblast proliferation and myotube differentiation (p < 0.05), while knockdown exerted the opposite effects. At the genetic level, the GG genotype of CKMT2 SNP (G.76,602,082 G>A) was associated with significantly higher BMW compared to the GA and AA genotypes (p < 0.05). These findings provide novel insights into the molecular basis of muscle weight variation in meat ducks and establish CKMT2 as a key regulator of skeletal muscle growth via modulation of myoblast proliferation and differentiation. This study contributes to the theoretical foundation for improving duck muscle yield through genetic selection.