Genome-Wide Selection Sweep Analysis to Identify Candidate Genes with Black and Brown Color in Tibetan Sibu Yaks

Abstract

Although coat color is an important economic phenotype in domesticated yaks (Bos grunniens), its genetic basis is not yet fully understood. In this study, a genome-wide selective sweep and high-frequency runs of homozygosity (ROH) identification were performed on 50 yaks with different coat colors to investigate candidate genes (CDGs) related to coat color. The results suggested that 2263 CDGs were identified from the 5% interaction windows of the FST and θπ ratio, along with 2801 and 2834 CDGs from black and brown yaks with iHS, respectively. Furthermore, 648 and 691 CDGs from black and brown yaks, which were widely enriched in pathways related to melanogenesis, melanocyte differentiation, and melanosome organization via GO and KEGG functional enrichment, respectively, were confirmed on the basis of the intersection of three parameters. Additionally, the genome of brown yaks presented more ROH, longer ROH fragments, and higher inbreeding levels than those of black yaks. Specifically, a large number of genes related to melanin synthesis and regulation (e.g., UST, TCF25, and AHRR) from the ROH islands were confirmed to be under strong selection. In summary, the results of this study enhance the understanding of the genetic basis for determining yak coat color.