Uncovering genes underlying coat color variation in indigenous cattle breeds through genome-wide positive selection

Abstract

The identification of candidate genes related to pigmentation and under selective sweep provides insights into the genetic basis of pigmentation and the evolutionary forces that have shaped this variation. The selective sweep events in the genes responsible for normal coat color in Indian cattle groups are still unknown. To find coat color genes displaying signs of selective sweeps in the indigenous cattle, we compiled a list of candidate genes previously investigated for their association with coat color and pigmentation. After that, we performed a genome-wide scan of positive selection signatures using the BovineSNP50K Bead Chip in 187 individuals of seven indigenous breeds. We applied a wide range of methods to find evidence of selection, such as Tajima's D, CLR, iHS, varLD, ROH, and F_ST. We found a total of sixteen genes under selective sweep, that were involved in coat color and pigmentation physiology. These genes are <i>CRIM1</i> in Gir, <i>MC1R</i> in Sahiwal, <i>MYO5A, PMEL</i> and <i>POMC</i> in Tharparkar, <i>TYRP1, ERBB2,</i> and <i>ASIP</i> in Red Sindhi, <i>MITF, LOC789175, PAX3</i> and <i>TYR</i> in Ongole, and <i>IRF2, SDR165</i> and, <i>KIT</i> in Nelore, <i>ADAMTS19</i> in Hariana. These genes are related to melanin synthesis, the biology of melanocytes and melanosomes, and the migration and survival of melanocytes during development.