Mitochondrial DNA D-loop hyper-variable region 1 variability in Kurdish horse breed

Background: Kurdish horse is one of the most valuable horse genetic resources in the Middle East. Objectives: To assess the genetic diversity of Kurdish horses, Mitochondrial DNA D-loop hyper-variable region1 (HVR1) was sequenced in 29 non-related Kurdish horses which were sampled from diverse geographic regions of Iran. Methods: Total DNA was extracted from the collected blood samples by modified salting out method. The HVR1 was amplified by PCR and then sequenced using ABI PRISM BigDyeTM Terminator Cycle Sequencing Ready Reaction Kit. Consequently, the sequences were trimmed to 294 bp using BIOEDIT to become comparable with other reported HVR1 sequences in GeneBank. Sequence alignment was performed using CLUSTALW package. Haplotype and nucleotide diversity were estimated using DNASP5.10 and phylogenetic tree was constructed by neighbour joining method. Results: Fourteen different haplotypes and 22 polymorphic sites were detected. Haplotype diversity, nucleotide diversity and Tajima D values were 0.901 +/- 0.001, 0.01153 +/- 0.0020 and -1.378, respectively. Kurdish horse showed a high haplotype and low nucleotide diversity. The compositional frequency of consensus sequences for base A was the highest (29.93%) compared to other three nucleotides (C = 28.91%, T = 26.53% and G = 14.63%). As expected, all of the detected Kurdish horse haplotypes belonged to haplogroup K (i.e., Kurdish horses). Conclusions: According to the phylogenetic analysis, Kurdish horses were genetically more closely related to Tibetan, Chinese, Bulgarian and Iranian native horse breeds, compared to other Asian horse breeds, but some traces of European horse breeds were detected in their maternal lines.

Automated summary

This study assessed the genetic diversity of Kurdish horses from different regions of Iran. The results showed that Kurdish horses have high haplotype diversity and low nucleotide diversity. Phylogenetic analysis revealed that Kurdish horses are genetically closer to Tibetan, Chinese, Bulgarian, and Iranian native horse breeds.