Genetic Basis of Divergent Growth and Muscle Development in Purebred and Crossbred Leizhou Black Goats Revealed by Whole-Genome Resequencing

The Leizhou black goat is a prized indigenous breed in southern China, renowned for its superior meat quality. However, its productivity is constrained by a relatively small body size. Understanding the genetic basis of growth differences between purebred and crossbred populations is essential for designing effective conservation and breeding strategies. To this end, we conducted comparative whole-genome resequencing on 22 purebred (WL) and 50 crossbred (JN: Nubian × Leizhou) goats. Population structure was assessed via principal component analysis, and genomic regions exhibiting elevated genetic differentiation were identified using the population differentiation index (FST). Functional enrichment analyses were subsequently applied to genes within these regions. Our results revealed clear genetic differentiation between the two populations. Among the highly differentiated genomic regions, we identified several genes, such as MYOM2, TMTC4, DPP6, and MIDN, whose known functions in neural signaling and muscle development make them plausible candidates for contributing to the growth differences between populations. A particularly notable discovery was a non-coding intronic mutation in the RNGTT gene (rs646826802), which is fixed in the paternal Nubian line and prevalent across 25 other global goat breeds but is completely absent in the purebred Leizhou black goat. This study identifies key genetic components associated with trait variation in crossbred goats and reports a breed-specific genomic marker that can serve as a practical tool for verifying breed purity, thereby supporting the conservation of this valuable indigenous genetic resource.