Sex-linked dilution colour in the European domestic goose confirmed to be a 1-bp deletion in the Melan-A gene

Plumage colour in domestic geese is an important economic trait and a selection target since the early days of domestication. In European domestic geese of greylag goose (Anser anser) origin, white plumage colour is known to be caused by two independent loci, one causing white spotting and one causing sex-linked dilution, together producing white plumage. Strong candidate mutations have been identified upstream of the EDNRB2/LOC106047519 gene (endothelin receptor B-like) and within the sex-linked MLANA gene (melan-A). To confirm these candidate mutations, we genotyped differently coloured European domestic goose breeds, wild greylag geese, Chinese domestic geese (derived from swan goose A. cygnoid) and European and Chinese domestic geese crossbreeds. One base pair deletion in the MLANA gene (NW_013185876.1: g.950,868 C > -) was confirmed to cause sex-linked dilution, and thus autosexing (almost white gander and goose diluted grey). However, mutation upstream of EDNRB2/LOC106047519 (NW_013185915.1: g. 775,151 G > T) was not the causative mutation for saddleback pattern but strongly linked to it in European domestic geese. We sequenced the EDNRB2 gene and coding sequence of a neighbouring VAMP7 gene (vesicle-associated membrane protein 7) but found no genetic variaion linked to colour. Additionally, we sequenced the coding sequence of TYRP1 (tyrosinase related protein 1), a candidate gene for buff colouration, but no variation linked to colour was found. Further, we genotyped a 14-bp insertion in exon 3 of the EDNRB2 gene, known to be causative of the white phenotype in the Chinese domestic goose, and identified it in one European domestic goose individual.