Detection of polymorphism in GDF9 gene and its association with twining in Baluchi sheep using RFLP-PCR

This study was carried out to evaluate the genetic polymorphism in GDF9 gene and its association with twining in Baluchi sheep. Blood samples were taken from 152 individuals and genomic DNA was extracted using modified salting out method. The quantitative and qualitative characteristics of extracted DNA was evaluated by spectrophotometric and gel electrophoresis method. Using a pairs of specific primers a DNA fragment with the size of 462 bp was amplified from exon 1 of GDF9 gene using polymerize chain reaction (PCR). The resulted PCR products were digested with HhaI restriction enzyme and the results showed a mutation at GDF9 locus in Baluchi sheep. The wild type allele (G+) with two restriction site resulted DNA fragments with the sizes 156، 52 and 254 bp while the mutant allele (G-) with one restriction site resulted two DNA fragments with the sizes of 52 and 410 bp. In heterozygous animals four DNA fragments with the sizes 52، 156، 254 and 410 bp were detected. The allelic frequency for G (+) and G (-) was estimated 0. 84 and 0. 16% and the frequency of genotypes G (+/+)، G (+/-) and G (-/-) were calculated 71، 26 and 3%، respectively. The observed، expected and average heterozygosity were calculated 0. 2697، 0. 2688 and 0. 2688، respectively. The χ2 test showed that the examined population is not in Hardy-Weinberg equilibrium at GDF9 locus (P<0. 005). The resulted of statistical data analysis for the effect of genotype on litter size was significant، since the ewes with heterozygote genotype had the highest mean litter size compared to the other two genotypes (P<0. 05). Thus، the litter size in sheep is low heritable، expressed only in females and did not manifest in early life، therefore، access to genetic markers can be used as an efficient and suitable tools in selection programs.