Genetic Diversity of Persian Arabian Horses and Their Relationship to Other Native Iranian Horse Breeds.

This research aims to understand the genetic diversity and selection signatures in Persian Arabian horses and their relationship with other Iranian horse breeds. Analyses found high genetic diversity in the Persian Arabian breed and identified 15 genomic regions potentially under selection. The study also showed a clear genetic differentiation between the Arabian breed and Turkemen and Caspian breeds.

Genetic Diversity and Inbreeding Measures

• The researchers examined 71 horses from eight different matrilineal strains, all tracing back to 47 mares from the mid to late 19th century.
• They used the equine 670k single nucleotide polymorphism (SNP) BeadChip, a tool used to measure genome-wide polymorphisms.
• The mean observed and expected heterozygosity were 0.43 and 0.45, respectively. Heterozygosity is a measure of genetic diversity, so these middle-level values suggest a decent level of genetic diversity in Persian Arabian horses.
• Average inbreeding measures were low, which aligns with the presence of high genetic diversity in this breed.

Population Genetic Structure

• Studies using STRUCTURE and principal component analysis indicated that Persian Arabian horses could be divided into three groups.
• Interestingly, these groups did not align with traditional matrilineal strains, suggesting that there may be other factors influencing the genetics of these horses.
• In total, 15 genomic regions were identified by Tajima’s D, H and H12 methods as potentially under selection, most of which were found on chromosome 9.
• This chromosome has been associated with horse temperament, suggesting that these genetic features may have been selected for in Persian Arabian horses.
• Biological function analysis of the identified candidate genes showed enrichment of the gene ontology (GO) term “response to lipopolysaccharide” and the KEGG pathway “chemokine-mediated signaling pathway”. These are associated with immune responses, indicating they may have been targets of selection in Persian Arabian horses.

Genetic Relationship with Other Iranian Horse Breeds

• The study also involved independent analyses of SNP data from 30 horses across four other Iranian breeds. The results suggested a distinct population structure between Persian Arabian horses and Turkemen and Caspian horse breeds.
• This points to a clear genetic differentiation between these breeds, even though they are all native to the same geographic region.
• The results of this study underline the rich genetic diversity in Persian Arabian horses and highlight the importance of understanding population genetic structure in maintaining the health and diversity of horse breeds.