Genome-wide Association Study Reveals the IBSP Locus Affect Ear Size in Cattle

Abstract BackgroundEar size is a classical model for hot climate adaptation following evolution, however, the genetic basis of the traits associated with the ear size remains to be elucidated.ResultsIn the current study, we performed GWAS on 158 cattle individuals to to explain the genetic mechanism of ear size. The results suggested significant association of IBSP locus with ear size. A missense mutation (Threonine-250→Isoleucine) on the seventh exon of IBSP was observed, which occurred at a quite conserved site and changed the three-dimensional (3D) structure simulations. In addition to GWAS, 14 cattle breeds were screened for the selection signals associating with the ear size using Fst and SweepD. The selective sweep analysis also suggested that IBSP was under positive selection amongst 4 breeds with relatively large ear size. The allele distribution of this mutation was validated among 394 samples from 21 worldwide cattle breeds, which strongly implied the origin of the A allele mutation to be from the Bos taurus.ConclusionsThese findings not only have important theoretical significance for the exploration of major genes associated with the ear size but also provide important molecular markers for the identification of cattle germplasm resources.