Association of FOXO3 gene polymorphisms with egg-laying intervals in pigeon

The egg-laying interval reflects the laying performance of pigeons and is affected by the mechanism of ovulation. The Forkhead box O3 (FOXO3) gene is closely associated with follicular development, playing roles in the regulation of follicular granulocyte proliferation, differentiation and periodic ovulation. The objective of this research was to analyze associations of polymorphisms of FOXO3 gene with egg-laying intervals in pigeon. A total of 250 female pigeons of Tianxiang 1 strain were used as experimental materials. Primers were designed according to the sequence of FOXO3 gene in pigeons, and single nucleotide polymorphisms (SNP) of FOXO3 gene were detected by sequencing of PCR products. Twenty SNP sites were found, and 7 of them were located in exons, 1 of them was located in intron, and 12 of them were in the 3' untranslated region (3'UTR) of the gene. Linkage disequilibrium (LD) analysis showed that four blocks were constructed from 20 SNPs. Association analysis showed that 6 SNPs (g.3149417 G > A, g.3149444 C > T, g.3149486 A > G, g.3150038 T > C, g.3151252 G > T and g.3152087 A > G) were significantly associated with egg-laying intervals. Furthermore, we found that the haplotypes of block1 and block4 were significantly correlated with egg-laying intervals. These results suggested that the FOXO3 gene may serve as a candidate gene for laying performance of pigeon.