Molecular cloning of the gooseGnRHgene and identification ofGnRHpolymorphisms associated with laying traits

1. Egg-laying traits are important economic characteristics in goose production (Anser cygnoides). The geneGnRH, which encodes gonadotropin-releasing hormone, is a strong candidate gene for egg-laying traits in avian species. 2. In this study, a 3520 bp genomic sequence and a 279 bp mRNA sequence forGnRH, which encoded 92 amino acids, were determined. TheGnRHDNA sequence contains four exons and three introns, and the DNA and deduced amino acid sequences were highly conserved across mammals (human, macaque, cow, and sheep) and avians (chicken, fulmar and quail). 3. Using a direct sequencing method, 46 single nucleotide polymorphisms (SNPs) were identified in theGnRHgenomic sequence that were shared between two Sichuan White goose populations (217 and 208 individuals). Furthermore, 44 haplotypes were constructed using a sliding window approach. Association analysis between the SNPs and haplotypes and egg-laying traits showed that 10 SNPs affected the first egg weight, average egg weight, egg number at 48 weeks and egg number at 64 weeks. 4. These results lay the foundation for further studies of the function ofGnRHin geese and provide a theoretical basis for marker-assisted selection of egg-laying traits in the Sichuan white goose population.