Study on the Correlation between Polymorphism of GDF9 Gene and Laying Performance in Chahua Chicken

PurposeTo explore the relationship between the SNPs of growth differentiation factor GDF9 and the egg production traits in Chahua chicken, and to lay a basis for further study on the genetic variation and provide a guidance to breed higher egg production traits.

MethodSNPs were screened by direct sequencing in Chahua chickens, and the difference analysis of different genotypes’ age, body weight at first egg laying as well as egg numbers at 300-day-old. qPCR technology was used to detect the expression of GDF9 in various tissues between high and low laying groups.

Results5 SNPs were obtained including g.1642A>T, g.1652A>G, g.1804A>G, g.2008C>T and g.2281T>C. Among them, g.1652A>G mutation caused isoleucine (Ile) to valine (Val). The analysis of population genetic parameters showed that the predominant alleles of g.1642A>T, g.1652A>G, g.1804A>G, g.2008C>T and g.2281T>C are A, G, G, T and T, respectively. All SNPs meet Hardy-Weinberg equilibrium except g.1642A>T. And g.1652A>G, g.2281T>C were moderately polymorphic sites. The results of the association analysis showed that AA genotype had highest body weight at first egg in g.1652A>G, while AG was highest in egg numbers at 300-day-old. TT genotype had earliest age at first egg laying in g.2281T>C. The expression trend of GDF9 gene in high and low egg production groups was consistent from high to low in the three tissues of ovary, pituitary and hypothalamus.

ConclusionThis study revealed that GDF9 gene has a certain effect on the laying traits of Yunnan Chahua chickens. g.1652A>G and g.2281T>C may be important SNPs that affect laying traits of Chahua chickens.