Ear type in sheep is associated with the MSRB3 locus

Abstract

Ear morphology is an important determinant of sheep breeds. It includes different variable traits such as ear size and erectness, suggesting a polygenic architecture. Here, we performed a comprehensive genome-wide analysis to identify regions under selection for ear morphology in 515 sheep from 17 breeds fixed for diverse ear phenotypes using 34k SNP genotyping data. GWASs for two ear type traits, size and erectness, revealed a single genome-wide significant association on ovine chromosome 3. The derived marker alleles were enriched in sheep with large and/or floppy ears. The GWAS signal harboured the MSRB3 gene encoding methionine sulphoxide reductase B3, which has already been found to be associated with different ear types in other species. We attempted whole-genome resequencing to identify causal variant(s) within a 1 Mb interval around MSRB3. This experiment excluded major copy number variants in the interval, but failed to identify a compelling candidate causal variant. Fine-mapping suggested that the causal variant for large floppy ears most likely resides in a 175 kb interval downstream of the MSRB3 coding region.

All sheeps and sizes: a genetic investigation of mature body size across sheep breeds reveals a polygenic nature

“…for its association with large and/or floppy ear type in sheep using a population‐based approach (Paris et al . 2020). MSRB3 has also been shown to regulate ear size in pigs (Zhang et al .…”

Unravelling the effect of environment on the genome of Sarda breed ewes using Runs of Homozygosity

“…It was found in selection signatures in local breeds of sheep (de Simoni Gouveia et al, 2017;Signer-Hasler et al, 2019) and cattle (Bertolini et al, 2020;Suezawa et al, 2021). Interestingly, the abovementioned MSRB3 gene, found in the ROH island detected on OAR3, has been also associated with the ear type (Paris et al, 2020). Another is the CHCHD7 that was found in selection signatures in cattle and sheep (Randhaw et al, 2014;Zhao et al, 2015).…”

Long divergent haplotypes introgressed from wild sheep are associated with distinct morphological and adaptive characteristics in domestic sheep

“…RXFP2 was strongly associated with sheep horn morphology (Johnston, et al 2011; Kijas, et al 2012), and SUPT3H was reported to be associated with nose bridge breadth(Adhikari, et al 2015), nose morphology(Claes, et al 2018), chin dimples(Pickrell, et al 2016) and forehead protrusion (Bonfante, et al 2021). MSRB3 had been identified as a candidate gene for external ear morphology in pig, dog, goat and sheep (Boyko, et al 2010; Webster, et al 2015; Wei, et al 2015; Zhang, et al 2016; Zhang, et al 2017; Chen, et al 2018a; Kumar, et al 2018; Paris, et al 2020). Furthermore, several other genes (e.g., STXBP5L, DENND1A, VPS13B ) were identified in GWAS studies of human facial shape analyses (Claes, et al 2018; Bonfante, et al 2021; White, et al 2021).…”

“…S14 ). Interestingly, ear morphology has been mapped to MSRB3 in sheep using breeds fixed for divergent ear types (Paris et al, 2020), designated as ear size (large-eared vs. small-eared) and ear erectness (drop-eared vs. prick-eared). This gene yielded significant f d values in 9 pairwise comparisons of argali vs. domestic population, encompassing chr3:154,000,001-154,090,000 ( Fig.…”