Polymorphism identification in GDF9 gene and its association analysis with reproduction traits in Jinghai Yellow chicken

GDF9 (growth differentiation factor 9) belongs to the transforming growth factor-b (TGF-b) superfamily and plays an irreplaceable role in female fertility. To reveal its genetic effects on productivity performance in chickens, 373 Jinghai Yellow chickens were chosen randomly to detect SNPs in GDF9 by PCR-SSCP and DNA sequencing methods. Eventually, four SNPs (g.2053G> A, g.2275T> C, g.2338C> T, g.2420T> C) in total had been detected. Amongst them, g.2420T> C was first found significantly associated with reproduction trait in chickens and heterozygous type C2T2 had higher average egg weight at 300 days of age (AEWD300) than T2T2 (p< 0.01). Least squares analysis showed that age at first laying (AFE) of H1 and H1H1 chickens were significantly earlier than that of H7 and H7H7 ones, respectively (p< 0.05). H1H5 hens showed higher AEWD300 than H4H7 ones (p< 0.05). For total egg number at 300 days of age (END300), mean of H5H5 was significantly higher than that of H4H4 (p< 0.05). Hence, the study suggested that hybrid vigor at g.2420T> C could be utilized in practice. H1H1, H1H5 and H5H5 could be the dominant diplotypes for chicken breeding. The study may contribute to the breeding progress of productive chickens and supply reference for oviparous animal production practice.