Mitochondrial DNA Cytochrome-b variability in Iranian Kurdish horse

Document Type : Research Paper


1 Department of Animal Science, College of Agriculture and Natural Resources, Razi University, Kermanshah, Iran.

2 Department of Animal Science, College of Agriculture and Natural Resources, Razi University, Kermanshah, Iran

3 Animal Science Research Institute of IRAN (ASRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran.


Investigation of mitochondrial genome sequence of cytochrome-b region within population can be a good indicator for diversity in the studied population. A recent study was conducted to investigate the genetic diversity in Kurdish horses and phylogenetic relationship of between Kurdish horse with other horse breeds in the world using cytochrome-b region. Blood samples were collected from 30 Kurdish horses and total DNA was extracted by modified salting out method. Cytochrome-b sequences were amplified by primers pairs with 1029 bp length and then were sequenced after purifying. The sequences were trimmed to 882 bp using BioEdit software. The samples were aligned with the horse reference sequence with access number (X79547) using Clustal-W package. Haplotype and polymorphic site numbers, Haplotype and nucleotide diversity were estimated using DNASP4 software. Phylogenetic tree was constructed in MEGA7 software by neighbor joining method. 7 haplotypes with 7 polymorphic site were identified. Whole haplotypes were belonged to K haplogroup. Haplotype and nucleotide diversities were 0.784±0.001 and 0.00218±0.001, respectively. The compositional frequency of consensus sequences was including: A base, 21.27%; C base, 32.77%; G base, 13.15% and T base, 26.87%. According to the phylogenetic analysis, Kurdish horses were genetically more closely related to Japanese and Chinese breeds and one Polish and Saudi Arabian breeds which shows that Kurdish horse has genetic similarities with Asian and some European horse breeds.


Main Subjects

Extended Abstract


Comparative sequence analysis of mitochondrial DNA (mtDNA) represents the standard molecular approach for species identification, with a particular emphasis on the cytochrome (cytb) gene. The most common molecular genetic approaches to species identification involve analysis of the mitochondrial DNA cytochrome b gene in nucleotide sequence of the cyt b gene contains species specific. Cytochromeb (cyt-b) has been considered as one of the most useful genes for phylogenetic work, and is probably the best-known mitochondrial gene with respect to structure and function of its protein product. Kurdish horse is one of the most valuable horse genetic resources in the Middle East. Despite the existence of a diverse range of different breeds on native horses in Asia, genetic research on some of these horse breeds, such as the Kurdish horse, is rare.



Therefore, Our main goals in the present study is to explore the utility of cyt-b to identify genetic structure and genetic variations in Kurdish horse and determination of phylogenetic relationships between Kurdish horses and other horse breed in the world.


Materials and Methods

Total DNA was extracted from the collected blood samples by modified salting out method. The cytochrome b was amplified by PCR and then sequenced using ABI PRISM BigDyeTM Terminator Cycle Sequencing Ready Reaction Kit. Consequently, the sequences were trimmed to 882 bp using BIOEDIT to become comparable with other reported cytochrome b 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.



Based on results, 7 different haplotypes and 7 polymorphic sites were detected. The largest haplotype

group consisted of 12 individuals. Haplotype diversity and nucleotide diversity 0.784±0.001and 0.00218±0.001, respectively. Kurdish horse showed a high haplotype and low nucleotide diversity. The compositional frequency of consensus sequences for base A was the highest (27.21%) compared to other three nucleotides (C = 32.77%, T = 26.87% and G = 13.15%).



According to the phylogenetic analysis, Kurdish horses were genetically more closely related to Japanese (Hokkaido and Yakutia), Chinese (Lijiang and Sanhe), Polish and Arabic hors breeds, which indicates the greater genetic similarity of the Kurdish horse with Asian and to some extent European breeds.

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