Comparison and transcriptomic analysis of embryonic leg muscle development differences between Shitou and Wuzong goose.

Shitou goose (STE) and Wuzong goose (WZE) are both characteristic goose breeds in Guangdong, China. Their growth cycle is similar, but there are huge differences in body size. One of the reasons for the difference in body size is the individual muscle mass, which is determined by myofiber development. The number of myofibers is fixed as early as the embryonic stage. Therefore, in this study, the leg muscles of 15, 23-day-old geese embryos (E15, E23), and the first day of hatching (P1) goslings of both STE and WZE were selected for analysis. Muscle tissue samples were subjected to histological sectioning and staining for morphological analysis. Differentially expressed genes (DEGs) across developmental stages were identified through systematic screening. An expression map of the identified DEGs was generated, and a gene interaction network was constructed to elucidate potential regulatory mechanisms. The results showed that the leg muscle development of STE at the embryonic development stage was superior to that of WZE. Through GO and KEGG analyses, it was found that STE was significantly more enriched in processes related to muscle development than WZE. Analysis of the gene expression profiles of STE and WZE revealed different manifestations, and it was observed that STE exhibited significantly more unique genes compared with WZE. We constructed the interaction network of myo-genes, including 77 genes in the network of STE and 17 genes in the network of WZE. We found that the unique gene interaction network in STE is more complex, suggesting that the potential regulatory environment of muscle development in STE may be more complex than that in WZE. The RT-qPCR results of nine identified myogenic genes (MYH7, MYO1F, MYOZ1, MYO5B, MYH11, ITGB8, MSTN, MFN2 and CCNB1) were consistent with the RNA-seq analysis. This study demonstrated that the developmental differences between STE and WZE originated during the embryonic stage. This study is the first to systematically compare the leg muscle development mechanisms of two goose breeds during embryonic stages. The results distinct developmental patterns and molecular regulation patterns of leg muscles between STE and WZE, providing a theoretical foundation for understanding the differences in myofiber development among different breeds.