Study On Polymorphism Of GDF9 Gene And Its Relationship With Prolificacy In Small Tailed Han Sheep

Based on the genetic polymorphism of GDF9 gene, we try to link this candidate gene with the high prolificacy of Small Tailed Han sheep, to further provide scientific evidence for the basic genetic research on the high productivity of Small tailed han sheep.Single nucleotide polymorphism(SNP)of GDF9 gene was detected in Small tailed han sheep,White Suffolk , Texel and Tibet sheep, respectively by PCR-SSCP. Four primers which designed according GDF9 sequence to amplify fragment in exon of GDF9 gene in sheep.The results indicated that one polymorphic locus in P2 primer was found AA, AB and BB genotypes were detected in Small Tail Han White Suffolk and Texel sheep. AA and AB genotypes were detected in Tibet sheep. In four sheep breeds, frequency of A-allele was64.1%,73.3%,73.35% and 81.65% respectively, and frequency of B-allele was 35.9%,26.7%,26.65% and 18.35% respectively. The sequencing results showed that BB genotype had a single nucleotide mutation as compared with AA genotype. Comparing with sequence of GDF9 gene (GeneBank AF 078545) indicated that BB genotype had a mutation (C→T) in 75 basic group. BB genotype was called mutate. The GDF9 genotype distributions were different (P<0.05) between Small tailed han sheep and Tibet sheep. The GDF9 genotype distributions were not different (P>0.05) between the other sheep breeds. The chi-square test (X2)showed that fragmentamplifiedby Primer2 was in a state of Hardy-Weinberg Equilibrium (HWE).The relationship of least squares means for little size was AB > AA >BB in Small tailed han sheep, but difference among the three genotype haven′t differ significantly(P>0.05).These results indicated that G2 mutation of GDF9 had no significant effect of Small tailed han sheep, then the possibility was that the fecundity of Small tailed han sheep was not affected by the G8 mutation of GDF9 gene.