Study On The Genetic Diversity Of Six Different Horse Types Based On CKM Gene

Chinese Mongolian Horse is one of the world's oldest horse breeds, experiencing genetic variation and natural selection during the evolutionary process, there has been gradually formed excellent Local Horse Breeds (such as Xinihe Horse, Baerhu Horse, Wushen Horse, Wuzhumuqin Horse) and also Cultivated Breed of Sanhe Horse in Inner Mongolia Autonomous Region. Mongolian Horses have characteristics of anti-cold, roughage resistance, disease resistance, endurance and well adaptability, which are valuable genetic resources to human being. But so far, there has been less systematic study about genetic diversity, origin and evolution, genetic relationship on Chinese Mongolian Horse at home and abroad.This paper firstly sequenced 612 bp fragment of the second intron of CKM gene in six horses breeds of 109 individuals by PCR and tested and compared the genetic polymorphism of CKM gene. The results were as follows:(1) Among 612 bp fragment of the second intron of CKM gene tested by local breeds of Mongolian Horse, Cultivated Breed of Sanhe Horse and Introduced Breed of Thoroughbred Horse, There were 23 polymorphic sites and 18 haplotypes. Haplotype sequences of CKM gene have been submitted to the GeneBank, Accession No. is HM151343-HM151360.(2) Nucleotide mutation type of the second intron of CKM gene are Insertion / Deletion, Conversion and Transversion. conversion frequency is significantly higher than that of transversion, which was showing strong conversion bias.(3) According to Phylogenetic Tree constructed by CKM gene sequence, Chinese Local Horse has multi-origins and experienced more domestication, speculating that original relationship between Thoroughbred Horse and Mongolian Horse is relatively far.(4) The 17th sites of 612 bp of 109 horses has a In/Del and produce 2 kinds of haplotypes, the haplotype diversity was 0.071, diversity of every sites of In/Del was 0.00012, the Tajima's D value was -0.70376, the difference was insignificant(P > 0.10).(5) There were 23 base substitutions not including In/Del, the sequence conservation was0.962, the fragment of 175-277(P=0.0132) and 338-497(P=0.0008) were conserved region.(6) Analysis of molecular variance shows that the difference between every types of Mongolian Horses and Thoroughbred Horse was insignificant.This paper firstly studied CKM gene and genetic polymorphism, which provide theoretical basis to appropriate use, exploitation and protection of genetic resources in Chinese horse breeds and racehorse selection in the future.