ABSTRACT
Arabian horse breeds (Equus caballus L.) are renowned for elegance, endurance and their contribution to Thoroughbreds. In heredity, the mitochondrial (mt) genome is maternally inherited and represents extensive genetic diversity. The mt genomes of Seglawi and Hadban horse breeds of Saudi Arabia were sequenced to decipher the genetic variations in the coding and non-coding regions. We observed that the coding region of mt genome has 11 and 34 amino acid variations in Seglawi and Hadban breeds, respectively. Sequencing analyses of COX1 gene indicated highest variations of which, 5 in Seglawi and 8 in Hadban followed by the NADH5 gene. The mitochondrial genes of respiratory chain showed positive selections with respect to different environments. Our data also highlighted that the Hadban breed had much higher nucleotide changes as compared to Seglawi and together they formed individual branches in phylogenetic tree. However, the tree shows that they were relatively branched to Arabian horse breeds. This study on two Arabian horses shed light on variations among mt genes and their phylogenetic relationship with other horse breeds.