Signatures of positive selection underlying beef production traits in Korean cattle breeds.

The difference in the breeding programs and population history may have diversely shaped the genomes of Korean native cattle breeds. In the absence of phenotypic data, comparisons of breeds that have been subjected to different selective pressures can aid to identify genomic regions and genes controlling qualitative and complex traits. In this study to decipher genetic variation and identify evidence of divergent selection, 3 Korean cattle breeds were genotyped using the recently developed high-density GeneSeek Genomic Profiler F250 (GGP-F250) array. The three Korean cattle breeds clustered according to their coat color phenotypes and breeding programs. The Heugu breed reliably showed smaller effective population size at all generations considered. Across the autosomal chromosomes, 113 and 83 annotated genes were identified from Hanwoo-Chikso and Hanwoo-Heugu comparisons, respectively of which 16 genes were shared between the two pairwise comparisons. The most important signals of selection were detected on bovine chromosomes 14 (24.39-25.13 Mb) and 18 (13.34-15.07 Mb), containing genes related to body size, and coat color (XKR4, LYN, PLAG1, SDR16C5, TMEM68, CDH15, MC1R, and GALNS). Some of the candidate genes are also associated with meat quality traits (ACSF3, EIF2B1, BANP, APCDD1, and GALM) and harbor quantitative trait locus (QTL) for beef production traits. Further functional analysis revealed that the candidate genes (DBI, ACSF3, HINT2, GBA2, AGPAT5, SCAP, ELP6, APOB, and RBL1) were involved in gene ontology (GO) terms relevant to meat quality including fatty acid oxidation, biosynthesis, and lipid storage. Candidate genes previously known to affect beef production and quality traits could be used in the beef cattle selection strategies.

Haplogroup Classification of Korean Cattle Breeds Based on Sequence Variations of mtDNA Control Region.

Many studies have reported the frequency and distribution of haplogroups among various cattle breeds for verification of their origins and genetic diversity. In this study, 318 complete sequences of the mtDNA control region from four Korean cattle breeds were used for haplogroup classification. 71 polymorphic sites and 66 haplotypes were found in these sequences. Consistent with the genetic patterns in previous reports, four haplogroups (T1, T2, T3, and T4) were identified in Korean cattle breeds. In addition, T1a, T3a, and T3b sub-haplogroups were classified. In the phylogenetic tree, each haplogroup formed an independent cluster. The frequencies of T3, T4, T1 (containing T1a), and T2 were 66%, 16%, 10%, and 8%, respectively. Especially, the T1 haplogroup contained only one haplotype and a sample. All four haplogroups were found in Chikso, Jeju black and Hanwoo. However, only the T3 and T4 haplogroups appeared in Heugu, and most Chikso populations showed a partial of four haplogroups. These results will be useful for stable conservation and efficient management of Korean cattle breeds.

Assessment of Genetic Diversity, Relationships and Structure among Korean Native Cattle Breeds Using Microsatellite Markers.

Four Korean native cattle (KNC) breeds-Hanwoo, Chikso, Heugu, and Jeju black-are entered in the Domestic Animal Diversity Information System of the United Nations Food and Agriculture Organization (FAO). The objective of this study was to assess the genetic diversity, phylogenetic relationships and population structure of these KNC breeds (n = 120) and exotic breeds (Holstein and Charolais, n = 56). Thirty microsatellite loci recommended by the International Society for Animal Genetics/FAO were genotyped. These genotypes were used to determine the allele frequencies, allelic richness, heterozygosity and polymorphism information content per locus and breed. Genetic diversity was lower in Heugu and Jeju black breeds. Phylogenetic analysis, Factorial Correspondence Analysis and genetic clustering grouped each breed in its own cluster, which supported the genetic uniqueness of the KNC breeds. These results will be useful for conservation and management of KNC breeds as animal genetic resources.

mtDNA Diversity and Phylogenetic State of Korean Cattle Breed, Chikso.

In order to analyze the genetic diversity and phylogenetic status of the Korean Chikso breed, we determined sequences of mtDNA cytochrome b (cyt b) gene and performed phylogenetic analysis using 239 individuals from 5 Chikso populations. Five non-synonymous mutations of a total of 15 polymorphic sites were identified among 239 cyt b coding sequences. Thirteen haplotypes were defined, and haplotype diversity was 0.4709 ranging from 0.2577 to 0.6114. Thirty-five haplotypes (C1-C35) were classified among 9 Asia and 3 European breeds. C2 was a major haplotype that contained 206 sequences (64.6%) from all breeds used. C3-C13 haplotypes were Chikso-specific haplotypes. C1 and C2 haplotypes contained 80.5% of cyt b sequences of Hanwoo, Yanbian, Zaosheng and JB breeds. In phylogenetic analyses, the Chikso breed was contained into B. taurus lineage and was genetically more closely related to two Chinese breeds than to Korean brown cattle, Hanwoo. These results suggest that Chikso and Hanwoo have a genetic difference based on the mtDNA cyt b gene as well as their coat color, sufficient for classification as a separate breed.