Association Analyses Of Mutations In BMPR-IB,GDF9 And BMP15 Genes With Litter Size And Identification Of Mutation In BMP15 Gene In Sonid Sheep

Sonid sheep breed,as a major and primitive population of Mongolian sheep,exist in grassland of Sonid Left and Right Banner of Inner Mongolia.Recently,the mutton of Sonid sheep is widely recognized as natural green food,become more and more famous in China.However,due to slower growth rate,low prolificacy(almost single ovulation)and traditional grazing system,the production rate of Sonid sheep has been limited.The objectives of this study were to genotype the 10 mutations in the BMPR-IB,BMP 15 and GDF9 genes by PCR-RFLP,to sequence in Sonid sheep,and to investigate the effects of the 10 mutations of the three genes on the prolificacy of Sonid Sheep.Total of 300 Sonid sheep including 188 ewes with single lambs and 112 ewes with twins lambs were selected,and 50 Small Tail Han sheep as well as 50 Hu sheep were as high prolificacy control groups.The results showed that:(1)The FecB mutation(A746G)was detected in four Sonid ewes in the population with birth of twins.The frequency of AG genotype and GG genotype were 0.089 and 0.009 in Sonid ewes of twins lambs,and the frequencies of A and G allele were respectively 0.946 and 0.054.The PIC of FecB mutation site in our selected Sonid sheep populatin was 0.097,showing low diversity.The favourly G allelic frequency was significantly higher in the ewes of twins lambs than the ewes of single lamb(P<0.01).The association analysis of the FecB genotype and litter size showed the litter size of AG genotype was significantly higher than AA genotype(P<0.001).(2)None polymorphism of the five mutations of FecXB,FecXL,FecXH,FecXG and FecXI in BMP 15 gene was found in the Sonid sheep and all of them were wild genotype.(3)None polymorphism of the three mutations FecGH,FecGF,FecGE and G4 in GDF9 gene were observed.(4)We identificated 6 novol mutations A115G,G117A,C342A,G419A,A1168G and G2129T in the BMP15 gene of Sonid sheep by direct sequencing.These results suggested that FecB mutation could be utilized as moleculat marker for improving Sonid sheep fecundity,and indicated that Sonid sheep breed has specific molecular genetic mechanism in ovulation.