Genetic variation among pelt sheep population using microsatellite markers
Genetic variation in three Iranian pelt sheep breeds namely: Gray Shiraz, Zandi and Karakul were investigated using fifteen microsatellite loci. Genomic DNA was extracted from 360 blood samples by extraction kits and salting-out procedure with some modifications. The total number of alleles ranged from 6 to12 in loci. The fifteen tested loci were all polymorphic in the three breeds. The average direct count of heterozygosity overall loci in each tested breed was more than the expected heterozygosity. Tests of genotype frequencies for deviation from the Hardy-Weinberg equilibrium (HWE) were performed at each locus of overall breeds and revealed significant departure from HWE (P < 0.001) due to heterozygote excess. Polymorphism information content value in Gray Shiraz, Zandi and Karakul were 0.815, 0.808 and 0.808, respectively. Rate of inbreeding within the three breeds was not noticeable (global Fis = - 0.19). Low genetic differentiation was detected by estimation of Fst index between all pairs of breeds. Results showed that high level of genetic diversity was observed in pelt sheep. The phylogenetic tree based on Nei distances were drown using the neighbor-joining (NJ) and unweighted pair-group method using an arithmetic average (UPGMA). With both methods, Gray Shiraz and Karakul sheep populations were located together at one cluster and Zandi sheep population at another. The results can be useful in the development of breeding strategy for genetic improvement of pelt sheep in Iran.
Key words: Microsatellites, sheep, genetic, diversity.