Genetic diversity of Halla horses using microsatellite markers
© The Author(s). 2016
Received: 17 April 2016
Accepted: 17 October 2016
Published: 17 November 2016
Currently about 26,000 horses are breeding in Korea and 57.2% (14,776 horses) of them are breeding in Jeju island. According to the statistics published in 2010, the horses breeding in Jeju island are subdivided into Jeju horse (6.1%), Thoroughbred (18.8%) and Halla horse (75.1%). Halla horses are defined as a crossbreed between Jeju and Thoroughbred horses and are used for horse racing, horse riding and horse meat production. However, little research has been conducted on Halla horses because of the perception of crossbreed and people’s weighted interest toward Jeju horses.
Using 17 Microsatellite (MS) Markers recommended by International Society for Animal Genetics (ISAG), genomic DNAs were extracted from the hair roots of 3,880 Halla horses breeding in Korea and genetic diversity was identified by genotyping after PCR was performed.
Results and conclusion
In average, 10.41 alleles (from 6 alleles in HTG7 to 17 alleles in ASB17) were identified after the analysis using 17 MS Markers. The mean value of Hobs was 0.749 with a range from 0.612(HMS1) to 0.857(ASB2). Also, it was found that Hexp and PIC values were lowest in HMS1 (0.607 and 0.548, respectively), and highest in LEX3(0.859 and 0.843, respectively), and the mean value of Hexp was 0.760 and that of PIC was 0.728. 17 MS markers used in this studies were considered as appropriate markers for the polymorphism analysis of Halla horses. The frequency for the appearance of identical individuals was 5.90 × 10−20 when assumed as random mating population and when assumed as half-sib and full-sib population, frequencies were 4.08 × 10−15 and 3.56 × 10−8, respectively. Based on these results, the 17 MS markers can be used adequately for the Individual Identification and Parentage Verification of Halla horses. Remarkably, allele M and Q of ASB23 marker, G of HMS2 marker, H and L of HTG6 marker, L of HTG7 marker, E of LEX3 marker were the specific alleles unique to Halla horses.
Horses (: Equus caballus) were first domesticated 4000 years ago and they are one of the most important animals for human and currently, about 200 horse breeds are breeding in the world. In the past years they were used as meat animals, workhorses or transportation means, but nowadays they are used for the various purposes such as improvement of life quality and development of leisure culture.
Currently about 26,000 horses are breeding in Korea and 57.2% (14,776 horses) of them are breeding in Jeju island .
According to the statistics published in 2010 , the horses breeding in Jeju island are subdivided into Jeju horse (6.1%), Thoroughbred (18.8%) and Halla horse (75.1%). Halla horses are defined as a crossbreed between Jeju and Thoroughbred horses and are used for horse racing, horse riding and horse meat production. However, little research has been conducted on Halla horses because of the perception of crossbreed and people’s weighted interest toward Jeju horses.
This stduy was conducted to establish parentage and to certify purity of Halla horses using microsatellite markers through the scientific and systemic management and to understand the value of Halla horses as genetic resources at national level, and to obtain the basic information on the genetic discrimination from other breeds and conservation of purity and genetic improvement of Halla horses.
Animals and DNA extraction
For the analysis of DNAs using Microsatellite, 3,880 heads of Halla horse breeding in Korea were used. Genomic DNAs were isolated and extracted by the methods described by QuickGene DNA tissue kits (FUJIFILM, Japan) and the concentration and purity of extracted genomic DNAs were measured using ND-1000 UV-Vis Spectrophotometer (NanoDrop Technologies, USA) and used for the analysis.
Information on Microsatellite (MS) Markers
Genetic diversity of Halla horse was identified using 17 Microsatellite (MS) Markers (AHT4, AHT5, ASB2, ASB17, ASB23, CA425, HMS1, HMS2, HMS3, HMS6, HMS7, HTG4, HTG6, HTG7, HTG10, LEX3, VHL20) recommended by International Society for Animal Genetics (ISAG).
Composition of multiplex-PCR and PCR procedure
Multiplex-PCR was performed using Equine Genotpyes Panel 1.1 Kit (Thermo SCIENTIFIC) for genotyping of 17 MS Markers. By the manufacturer’s instructions, to the reaction mixtures Genomic DNA (1.0 ng/μl) 2 μl, Mater Mix 9 μl, and Primer Mix 9 μl were added, making a total of 20 μl and using GeneAmp PCR system 9700 (Applied Biosystems, USA) PCR was performed. PCR was performed in an initial denaturation at 98 °C for 3 min, followed by 30 cycles of 15 s at 98 °C, 75 s at 60 °C and 30s at 72 °C. The final extension step was at 72 °C for 5 min and then cooled to 4 °C.
Genotyping of Microsatellite (MS)
Using Hi-Di™ formamide, amplified PCR products were diluted to 50 ~ 100 times, and the diluted PCR products were diluted using Hi-Di™ formamide and GeneScan™-500LIZ™ size standard. After the capillary electrophoresis was performed using Genetic Analyzer 3130xl (Applied Biosystem, USA), the size of each MS marker was determined using GeneMapper version 4.1 (Applied Biosystems, USA). Data on the determined alleles were collected individually and applied to statistical analysis using Microsoft Excel (Microsoft, USA). Also, by the international equine comparison test standards recommended by ISBC (International Stud Book Committee) and ISAG (International Society of Animal Genetics) genotyping was performed and alphabetic allele nomenclature was applied.
Statistical analysis of data
Frequency, heterozygosity and polymorphism information content
Using Microsatellite Toolkit software  and Cervus ver 3.0 program , number of alleles, expected and observed heterozygosity (Hexp and Hobs) and Polymorphism information content (PIC) value were calculated.
Frequency of identical individuals
Using API-CALC ver 1.0 program , expected probabilities of appearance frequency of identical individuals in random individuals (PI), random half sibs (PIhalf-sibs) and random full sibs (PIfullsibs) mating population were calculated.
Results and discussion
Polymorphism of microsatellite markers
No. of Allele, Heterozygosity (observed and expected) and PIC value of microsatellite markers in Halla horses
No of allele
The mean number of alleles for 17 MS markers was 10.41 with a range from 6 (HTG7) to 17(ASB17). Cho  reported that there were 7.35 alleles in average with a range from 5(HTG4, HTG7) to 10 (ASB17) in the analysis of genetic characteristics and Genetic Relationship for Jeju horse, Mongolian horse, Thoroughbred and Warmblood when used the same 17 markers used in this study. Similar results were also reported by Cho , Cho et al.  and Lee et al. .
The mean value of Hobs was 0.749 with a range from 0.612(HMS1) to 0.857(ASB2). Also, Hexp and PIC values were lowest in HMS1 (0.607 and 0.548, respectively), and highest in LEX3 (0.859 and 0.843, respectively). For CA425 the number of alleles was relatively high (11), while Hobs, Hexp and PIC values were relatively low (0.623, 0.623 and 0.598, respectively).
While the number of alleles in HTG7 was lowest (6), Hobs, Hexp and PIC values were higher than those of CA425 (0.750, 0.749 and 0.706, respectively), suggesting that alleles in HTG7 were evenly distributed.
Botstein et al.  reported that when the expected heterozygosity was above 0.6 and Polymorphism Information Content (PIC) value of MS marker was above 0.5 it is considered as markers with high diversity. Therefore, the 17 MS markers used in this studies are considered as appropriate markers for the analysis of genetic diversity of Halla horses.
The expected probability of identity values
The expected probability values among genotypes of random individual (PI) for discrimination horse lines using markers
No. of Marker
3.20 × 10−2
8.09 × 10−2
3.09 × 10−1
1.22 × 10−3
7.33 × 10−2
9.77 × 10−2
4.76 × 10−5
6.70 × 10−2
3.11 × 10−2
2.04 × 10−6
6.52 × 10−5
1.00 × 10−2
1.08 × 10−7
7.29 × 10−6
3.37 × 10−3
6.10 × 10−9
8.50 × 10−7
1.14 × 10−3
3.49 × 10−10
1.01 × 10−7
3.89 × 10−4
2.30 × 10−11
1.31 × 10−8
1.36 × 10−4
1.58 × 10−12
1.83 × 10−9
4.87 × 10−5
1.30 × 10−13
2.73 × 10−10
1.78 × 10−5
1.23 × 10−14
4.44 × 10−11
6.66 × 10−6
1.03 × 10−15
7.00 × 10−12
2.49 × 10−6
9.90 × 10−17
1.18 × 10−12
9.47 × 10−7
2.29 × 10−13
3.78 × 10−7
1.79 × 10−18
5.66 × 10−14
1.69 × 10−7
3.10 × 10−19
1.48 × 10−14
7.66 × 10−8
5.90 × 10−20
4.08 × 10−15
3.56 × 10−8
Allele frequency of microsatellite markers
Although several studies [2, 8, 9, 12] reported population studies on the genetic pedigree structure of several horse breeds, only limited information is available about data needed in casework such as the power of identity and breed assignment [4, 16]. In this study, allele M and Q of ASB23 marker, G of HMS2 marker, H and L of HTG6 marker, L of HTG7 marker, E of LEX3 marker confirmed as the specific alleles unique to Halla horses. This result is considered that utilize for the basic information on genetic resource and genetic relationship analysis of Halla horses. Also, it is thought to used as scientific evidence that prove pedigree establishment, genetic differentiation and inherency of halla horses. Finally, It is considered to be a useful data in the improved ability to breed Halla horses.
This research was supported by the Genomic Informatics Center, Hankyong National University and korea Hallahorse Breeder’s Association.
Funding came from korea Hallahorse Breeder’s Association.
Availability of data and materials
JH carried out the molecular genetic studies and drafted the manuscript. KD and HK collected samples. HS conceived of the study, and participated in its design and coordination and helped to draft the manuscript. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
The study was approved by the HanKyung National University Animal Ethics Committee (No. 2015-4).
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
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