Researchers have mapped the entire genome of a Marwari horse for the first time. It is the first Asian horse breed to have its entire genome mapped.
The Marwari is a rare horse breed from the Marwar region of India, and is one of six distinct horse breeds in India. They are believed to be descended from native Indian ponies, which were crossed with Arabian horses beginning around the 12th century, possibly with some Mongolian influence.
The Marwari has unique characteristics, including inwardly turned ear tips.
Researchers from South Korea, Britain and the United States were involved in the research, the findings of which have been published in the journal, BMC Genomics.
The team mapped the genome from a blood sample taken from a 17-year-old male Marwari horse, in an analysis which generated 101 gigabytes of data.
The researchers confirmed a strong Arabian and Mongolian component in the Marwari genome.
Novel gene variations were noted, found to be involved in enriching the sense of smell. They also found a potential functional genetic variant in the TSHZ1 gene believed to be associated with the inward-turning ear tip shape that distinguishes the breed.
The scientists said the data gathered would be an invaluable resource for future studies of genetic variations associated with phenotypes and diseases in horses.
To date, several whole genomes of horses have been sequenced and analyzed. However, until now, currently available whole genome sequences of modern horses comprised only western Eurasian breeds.
The horse reference genome has provided fundamental genomic information on the equine lineage and has been used for improving the health and performance of horses. Horses have been found to exhibit 214 genetic traits and/or diseases that are similar to those of humans.
Over the centuries, more than 400 distinct horse breeds have been established by genetic selection for a wide number of desired traits.
Marwari horses were trained to perform complex prancing and leaping movements for ceremonial purposes. The population in India deteriorated in the early 1900s due to improper management of the breeding stock, and only a few thousand purebred Marwari horses remain.
To explore the relationships among breeds, the researchers compared the Marwari horse genome data with that from 729 individual horses belonging to 32 domestic breeds.
The Marwari horse fell together with Iberian-lineage breeds, such as the Andalusian, Mangalarga Paulista, Peruvian Paso, and Morgan horse breeds, all of which are known to have Arabian ancestry.
“Additionally, we found that the Marwari horse fell between Arabian and Mongolian horses, indicating their dual genetic influences on the Marwari horse as previously suggested,” Jong Bhak and his colleagues reported.
“These results indicate that the Marwari is genetically closely related to the Arabian and Mongolian horses. It is unclear whether the latter relationship represents direct genetic input from Mongolian horses or whether these horses are the closest population to the Indian ponies from which the Marwari is thought to have descended.
“Further analysis including Indian ponies and Marwari horses will be required to distinguish the relative importance of these two scenarios, which are not mutually exclusive.”
The researchers concluded: “The whole genome sequencing data from the Marwari horse provides a rich and diverse genomic resource that can be used to improve our understanding of animal domestication and will likely be useful in future studies of phenotypes and disease.”
Whole genome sequence and analysis of the Marwari horse breed and its genetic origin.
JeHoon Jun, Yun Sung Cho, Haejin Hu, Hak-Min Kim, Sungwoong Jho, Priyvrat Gadhvi, Kyung Mi Park, Jeongheui Lim, Woon Kee Paek, Kyudong Han, Andrea Manica, Jeremy Edwards and Jong Bhak.
BMC Genomics 2014, 15(Suppl 9):S4 doi:10.1186/1471-2164-15-S9-S4
The full study can be read here.