Genome-Wide Association Analysis Identifies Important Haplotypes and Candidate Gene XKR4 for Body Size Traits in Pekin Ducks.

Simple Summary: The body size of ducks reflects their skeletal development and growth status. However, the rapid growth and early large body size of meat ducks negatively affect subsequent slaughter and processing. Therefore, it is necessary to identify candidate genetic markers and genes involved in body size regulation. In this study, we conducted genome-wide association studies (GWASs) on the body length (BL), keel bone length (KBL), neck length (NL), and breast width (BrW) of 42-day-old Pekin ducks (Anas platyrhynchos domestica). The results showed that BL and KBL had similar GWAS signals. Based on these results, we further identified causal haplotypes and candidate genes affecting BL and KBL. This research provides new genetic insights into the growth and development of Pekin ducks and has important implications for their breeding improvement. Body size is an important growth indicator in ducks and is a primary selection criterion for physical improvement. An excessively rapid growth rate in meat ducks can result in excessive body size, which may hinder subsequent processing and slaughter operations. However, only a few molecular markers related to body size have been studied in meat ducks. In this study, we performed a genome-wide association study (GWAS) to identify candidate genes and QTLs affecting body length (BL), keel bone length (KBL), neck length (NL), and breast width (BrW) in Pekin ducks (Anas platyrhynchos domestica). Our results indicate the significant SNP for NL is located within a pseudogene, whereas the significant SNP for BrW is located in an intergenic region. More importantly, our analysis identified a haplotype that was significantly associated with both BL and KBL. This haplotype, containing 48 single-nucleotide polymorphisms (SNPs), is localized within the XKR4 gene. The identification of this haplotype suggests that XKR4 may be a key candidate gene influencing BL and KBL in Pekin ducks. These findings have important implications for the breeding and genetic improvement of Pekin ducks, and provide valuable insights into the genetic architecture of body size traits in this species. [ABSTRACT FROM AUTHOR]