Identification of candidate genes for chicken early- and late-feathering

Previous studies suggest that prolactin receptor (Prlr) is a potential causative gene for chicken early- (EF) and late-feathering (LF) phenotypes. In this study, we evaluated candidate genes for this trait and determined the expression of 3 genes, including Prlr, sperm flagellar protein 2 (Spef2), and their fusion gene, in the skins of one-day-old EF and LF chicks using RT-qPCR. Data indicated that Prlr expression in the skin did not show significant difference between EF and LF chicks, suggesting Prlr may not be a suitable candidate gene. In contrast, Spef2 expression in the skin displayed a significant difference between EF and LF chicks (P < 0.01), suggesting that Spef2 may be a good candidate gene for chicken feathering. Moreover, dPrlr/dSpef2, the fusion gene, was also a good candidate gene as it was expressed only in LF chicks. However, the expression of the fusion gene was much lower than that of Prlr Additionally, using strand-specific primers, we found that the fusion gene was transcribed in 2 directions (one from dPrlr promoter, another from dSpef2 promoter), which could result in the formation of a double strand RNA. In conclusion, both Spef2 and the fusion gene are good candidate genes for chicken feathering, but Prlr is not. The research on the function and regulation of the candidate genes will help elucidate the molecular basis of the chicken feathering trait.