Cloning and tissue expression profiling of the GnRHR gene of the Muscovy duck (Cairina moschata): polymorphism and association with egg-laying performance

1. cDNA sequence of gonadotropin-releasing-hormone receptor (GnRHR) gene was cloned and an association analysis between mutations and laying performance was conducted.

2. A 1680-bp cDNA sequence of Muscovy duck GnRHR, which encodes 415 amino acids, was obtained and characterised. Phylogenetic analysis revealed that Muscovy duck GnRHR has a close relationship with Gallus gallus GnRHR.

3. There were significantly different expression profiles between 4 age periods in the hypothalamus, pituitary, and ovary. The expression of GnRHR at the age of 36 weeks (laying period) was higher than other time points in the three tissues. GnRHR was expressed in 12 different tissues. The highest expression levels were observed in hypothalamus, pituitary and gonads.

4. A single nucleotide polymorphism detected in the second intron was associated with egg-laying performance. Individuals with genotype TT had better egg-laying performance from individuals with genotypes CC or TC. Therefore, GnRHR could be used as a marker gene for laying performance in Muscovy duck.