Genome-wide association analysis reveals that EDNRB2 causes a dose-dependent loss of pigmentation in ducks

Abstract

Background Birds have various plumage color patterns, and spot is a common phenotype. Herein, we conducted genome-wide association studies (GWAS) in a population of 225 ducks with different sized black spots to reveal the genetic basis of this phenomenon. Results First, we quantified the black spot phenotype within the duck population. The results showed that the uncolored area of the body surface first appeared on the ventral side. With increasing duck age, the area of the black spots was highly conserved across the whole body surface. The GWAS results identified a 198 kb (Chr4: 10,149,651 bp to 10,348,068 bp) genetic region that was significantly associated with the black spot phenotype. The conditional GWAS and linkage disequilibrium (LD) analysis further narrowed the ultimate candidate region to 167 kb (Chr4: 10,180,939 bp to 10,348,068 bp). A key gene regulating melanoblast migration and differentiation, EDNRB2 (Endothelin B receptor-like), was found in the candidate region and having significant mRNA expression level changes in embryonic duck skin tissue with different spot sizes. The significant SNPs (single nucleotide polymorphisms) associated with the EDNRB2 gene were annotated, and two mutations (Chr4: 10,180,939 T > C and Chr4: 10,190,671 A > T) were found to result in the loss of binding sites for two trans-factors, XBP1 and cMYB. The phenotypic effect of these two mutations suggested that they can regulate the size of black spots in a dose-dependent manner, and Chr4: 10,180,939 T > C was the major allele locus. Conclusions Our results revealed that EDNRB2 was the gene responsible for the variation in duck body surface spot size. Chr4: 10,180,939 T > C was the major allele that explained 49.5 % (dorsal side) and 32.9 % (ventral side) of the variation in duck body surface spot size, while 32.1 % (dorsal side) and 19.1 % (ventral side) of the variation could be explained by Chr4: 10,190,671 A > T. The trans-factor prediction also suggested that XBP1 and cMYB have the potential to interact with EDNRB2, providing new insights into the mechanism of action of these genes.

Genome-Wide Analysis Identifies Candidate Genes Encoding Feather Color in Ducks

“…Thus, MC2R mediates ACTH to promote melanin deposition, which leads to the formation of grey feathers; however, the specific mechanism requires further experimental verification. Other studies have also reported that the EDNRB2 is a candidate gene associated with black color in live animals and poultry [ 55 , 56 ]. EDNRB2 is a key gene involved in melanogenesis.…”

Genome-Wide Analysis Identifies Candidate Genes Encoding Beak Color of Duck

“…EDNRB signaling is required for melanocyte development [ 61 , 62 ]. Loss of function variants in EDNRB leads to white spotting phenotypes in humans, animals [ 63 , 64 ], and poultry [ 65 , 66 ]. A similar result was identified in our study, which showed that EDNRB2 regulated melanin pigmentation in ducks.…”

Genome-wide association analysis of the primary feather growth traits of duck: identification of potential Loci for growth regulation

“…Based on the P -value and/or marker effect in GWAS, it is easy to obtain the SNP's effect on a phenotypic trait. At present, molecular markers associated with reproductive ( Chang et al, 2012 ; Huang et al, 2013 ), carcass ( Wu et al, 2012 ), body size ( Zhou et al, 2018 ), feather color ( Xi et al, 2021 ), and eggshell ( Liu et al, 2021 ) color traits have been discovered in ducks. However, less publications reported on ducks' QTLs or SNPs associated with feather growth traits.…”