Association of single nucleotide polymorphism in melatonin receptor 1A gene with egg production traits in Yangzhou geese

In the present study the melatonin receptor 1A gene (MTNR1A) was proposed to be a candidate gene for egg production in Yangzhou geese. A total of 210 goose blood samples were collected to investigate the association of the MTNR1A gene with the number of eggs produced. Using a direct sequencing method, a single nucleotide polymorphism (SNP; g. 177G>C) was detected in the 5' regulatory region of the MTNR1A gene (Genbank ss1985399687). Two alleles (G and C) and three genotypes were identified. Association analysis results showed that the g. 177G> C SNP significantly affected the level of egg production within a 34-week egg-laying period (P < 0.05). Furthermore, the geese with the GG genotype produced significantly more eggs compared to the geese with the CC genotype. Quantitative real-time PCR analysis showed that the MTNR1A gene was highly expressed in small intestine, granulosa cell and ovary compared to other examined tissues. In addition, the mRNA expression level of MTNR1A in ovary indicated that significantly higher expression levels were recorded for geese with the GG genotype compared to those with the CC genotype. Moreover, a luciferase reporter assay showed that the CC genotype had significantly lower promoter activity than did GG. These results suggest that the identified SNP in the MTNR1A gene may influence the number of eggs produced and mRNA expression levels in Yangzhou geese and could be considered as a useful molecular marker in goose selection and improvement, especially for egg production.