title: The Mendelian inheritance of rare flesh and shell colour variants in the black-lipped pearl oyster (Pinctada margaritifera).
abstract: Pinctada margaritifera is French Polynesia's most economically important aquaculture species. This pearl oyster has the specific ability to produce cultured pearls with a very wide range of colours, depending on the colour phenotypes of donor oysters used. Its aquaculture is still based on natural spat collection from wild stocks. We investigated three rare colour variants of P. margaritifera - orange flesh, and red and white shell colour phenotypes - in comparison with the wild-type black flesh and shell commonly found in this species. The study aimed to assess the geographic distribution and genetic basis of these colour variants. Colour frequencies were evaluated during transfer and graft processes of pearl oyster seed captured at collector stations. Among the collection locations studied, Mangareva Island showed the highest rate of the orange flesh phenotype, whereas Takaroa and Takume atolls had relatively high rates of red and white shell phenotypes respectively. Broodstocks were made of these rare colour variants, and crosses were performed to produce first- and second-generation progenies to investigate segregation. The results were consistent with Mendelian ratios and suggest a distinct model with no co-dominance: (i) a two-allele model for flesh trait, whereby the orange allele is recessive to the black fleshed type, and (ii) a three-allele model for shell trait, whereby the black wild-type allele is dominant to the red coloration, which is dominant to the white shell. Furthermore, the proposed model provides the basis for producing selected donor pearl oyster lines through hatchery propagation.
authors.affiliation: Ifremer, UMR 241, EIO, Labex Corail, Centre du Pacifique, BP 9, 98719, Taravao, Tahiti, Polynésie Française. chinky@ifremer.fr.
authors.forename: Chin-Long
authors.initials: CL
authors.lastname: Ky
authors.affiliation: SCA Regahiga Pearls, BP 48, 98755, Rikitea, Archipel des Gambier, Polynésie Française.
authors.forename: Seiji
authors.initials: S
authors.lastname: Nakasai
authors.affiliation: Ferme perlière POMMIER, BP 3, 98761, Arutua, Archipel des Tuamotu, Polynésie Française.
authors.forename: Steve
authors.initials: S
authors.lastname: Pommier
authors.affiliation: Ifremer, UMR 241, EIO, Labex Corail, Centre du Pacifique, BP 9, 98719, Taravao, Tahiti, Polynésie Française.
authors.forename: Manaarii
authors.initials: M
authors.lastname: Sham Koua
authors.affiliation: Groupement d'Intérêt Economique Poe O Rikitea, BP 176, 98755, Rikitea, Archipel des Gambier, Polynésie Française.
authors.forename: Dominique
authors.initials: D
authors.lastname: Devaux
mesh_terms: D000483:Alleles; D060105:Animal Shells; D000818:Animals; D017756:Aquaculture; D003116:Color; D005799:Genes, Dominant; D005808:Genes, Recessive; D005838:Genotype; D040582:Inheritance Patterns; D008957:Models, Genetic; D010641:Phenotype; D010858:Pigmentation / Q000235:genetics*; D049911:Pinctada / Q000235:genetics*; D011114:Polynesia
keywords: aquaculture; colour segregation; cultured pearl; donor selection; hatchery-produced oyster; rare phenotype