Single-cell transcriptomics reveal mechanisms of skeletal muscle differentiation across duck embryonic development

Skeletal muscle development is cornerstone of vertebrate locomotion, relies on the functionally distinct muscle fiber-type. Although the cellular dynamics in myogenesis have been extensively studied, the developmental origins and pathways governing fiber-type diversification remain unresolved. Furthermore, the evolutionary conservation of these mechanisms across vertebrates is poorly understood. Thus, we generate a comprehensive single-cell transcriptomic atlas of duck skeletal muscle across embryonic development to explore the trajectory from myogenic progenitors to myofiber. We identified a differentiation mechanism whereby slow-twitch type could transdifferentiate into the fast-twitch type, a process mediated by LEF1+(I) subtype. Comparative analysis of datasets across vertebrates (avian and mammalian) reveals that this fiber-type conversion program is phylogenetically conserved, suggesting homology in muscle adaptation mechanisms. Our study provides the transcription factors roadmap of vertebrate myofiber development, bridging gaps in developmental and evolutionary biology. These insights advance fundamental knowledge of tissue patterning and hold translational potential for regenerative medicine and agricultural biotechnology.