Molecular genetics of coat colour variations in White Galloway and White Park cattle

Abstract

White Galloway cattle exhibit three different white coat colour phenotypes, that is, well marked, strongly marked and mismarked. However, mating of individuals with the preferred well or strongly marked phenotype also results in offspring with the undesired mismarked and/or even fully black coat colour. To elucidate the genetic background of the coat colour variations in White Galloway cattle, we analysed four coat colour relevant genes: mast/stem cell growth factor receptor (KIT), KIT ligand (KITLG), melanocortin 1 receptor (MC1R) and tyrosinase (TYR). Here, we show that the coat colour variations in White Galloway cattle and White Park cattle are caused by a KIT gene (chromosome 6) duplication and aberrant insertion on chromosome 29 (Cs29 ) as recently described for colour-sided Belgian Blue. Homozygous (Cs29 /Cs29 ) White Galloway cattle and White Park cattle exhibit the mismarked phenotype, whereas heterozygous (Cs29 /wt29 ) individuals are either well or strongly marked. In contrast, fully black individuals are characterised by the wild-type chromosome 29. As known for other cattle breeds, mutations in the MC1R gene determine the red colouring. Our data suggest that the white coat colour variations in White Galloway cattle and White Park cattle are caused by a dose-dependent effect based on the ploidy of aberrant insertions and inheritance of the KIT gene on chromosome 29.

Composite selection signals can localize the trait specific genomic regions in multi-breed populations of cattle and sheep

“…Region B8 contains the MC1R gene near the peak at 14.0-15.0 Mb position on BTA-18, where strong selection signatures have previously been identified involving several breeds that have also been used in the present study [15]. The melanocortin 1 receptor ( MC1R ) gene is the candidate for coat colour in cattle [13,15,20,72,73]. …”

A structural variant in the 5’-flanking region of the TWIST2 gene affects melanocyte development in belted cattle

“…During the investigation we excluded several animals that were reported as belted by the owners, but had only minimal white spots that did not resemble the typical belt phenotype. We also excluded several animals that were reported as non-belted by the owners, but turned out to be White Galloways, on which a belt would not have been visible [35]. The final cohort thus consisted of 333 belted animals and 1,322 non-belted cattle.…”

The challenges and importance of structural variation detection in livestock

“…Recently, a number of studies indicate a chromosomal translocation (and subsequent duplication) of the KIT gene in several cattle coat phenotypes ( Figure 2B ; Durkin et al, 2012; Brenig et al, 2013). Durkin et al (2012) found that a 492 kbp segment of BTA6 containing the KIT gene was translocated to BTA29 in several Brown Swiss and Belgian Blue cattle via two circular intermediate steps, and a reshuffling of the order of genes on the transferred segment.…”

“…While the translocation and incorporation of DNA circular intermediates has been well characterized in bacterial integron dynamics (Domingues et al, 2012), this is one of the first instances where a similar mechanism was detected in a mammalian species, let alone a complex double-translocation event. The implications of this new allele have extended beyond Brown Swiss and Belgian Blue cattle as White Galloway and White Park cattle were found to carry this allele (Brenig et al, 2013). Surprisingly, the effects of the modified KIT locus in these cattle result in mottled markings rather than color-sidedness, suggesting that the extent by which modification of KIT can influence coat color has not been fully explored (Brenig et al, 2013).…”

“…The implications of this new allele have extended beyond Brown Swiss and Belgian Blue cattle as White Galloway and White Park cattle were found to carry this allele (Brenig et al, 2013). Surprisingly, the effects of the modified KIT locus in these cattle result in mottled markings rather than color-sidedness, suggesting that the extent by which modification of KIT can influence coat color has not been fully explored (Brenig et al, 2013). …”