Phylogenetic Analysis of Korean Black Cattle Based on the Mitochondrial Cytochrome b Gene

The purpose of this study was to identify genetic polymorphisms of the mitochondrial cytochrome b (mtDNA cyt b) gene in Korean black (KB) cattle breed and to analyze the genetic relationship between the KB and other breeds. We determined the complete sequence of the mtDNA cyt b gene in 38 KB cattle. We also analyzed their genetic diversity, and phylogenetic analysis was performed by comparison with Korean cattle (KC, called Hanwoo) and breeds from China and Japan. A nucleotide substitution was detected in the KB cattle, and two haplotypes were defined. In the neighbor-joining (NJ) tree, the haplotypes of KB were located in Bos taurus lineage with those of KC, Japanese black (JB), Yanbian and Zaosheng breeds. However, the haplotypes of Chinese breeds, excluding Yanbian and Zaosheng, were separated into B. taurus and B. indicus lineages. In the NJ tree of breeds based on Dxy genetic distances, Chinese breeds mixed with B. taurus and B. indicus lineages were located between B. indicus and B. taurus lineages. KB was contained within B. taurus lineage and was determined to be genetically more closely related to two Chinese (Yanbian and Zaosheng) breeds than to KC and JB. The haplotype distribution and the results of the phylogenetic analysis suggest that KB and KC have genetic differences in their mtDNA cyt b gene sequences.