Single Nucleotide Polymorphisms (SNPs) of GDF9 Gene in Bahmaei and Lak Ghashghaei Sheep Breeds and Its Association with Litter Size

Growth differentiation factor 9 (GDF9) belong to the superfamily of transforming growth factor β that is highly expressed in growing ovarian follicles of oocyte, and it has been strongly related to fecundity traits in sheep. Therefore, the GDF9 gene could serve as a genetic marker for improvement of reproductive performance in sheep. Therefore, the aim of this study was to investigate the fecundity gene of GDF9 in two local sheep breeds, Bahmaei and Lak Ghashghaei, reared at Kuhgiloyeh and Boyer-Ahmad province of Iran. For this purpose, genomic DNA was extracted from 20 Bahmaei and 20 Lak Ghashghaei (10 single birth, 10 twin births in each breed) multiparous ewes. The entire length of exon 1 and 2 in ovine GDF9 gene was amplified using three designed primer pairs, and detection of single nucleotide polymorphisms (SNPs) in the amplified fragments was determined by direct DNA sequencing method. The first and third amplified fragments of ovine GDF9 showed single genotype in two breeds. Sequencing results of the second fragment (P2) discovered 4 SNPs, including 3 SNPs in coding sequence of exon 2 and one novel in intron of GDF9 gene. No significant association was obtained between combined genotypes of identified SNPs with litter size in both sheep breeds. In general, the two sheep breeds were different in their genetic structure with regard to the GDF9 gene. Frequency distributions of identified SNPs in exon 2 GDF9 gene were different in two sheep breeds.