Colour plasticity in the shells and pearls of animal graft model Pinctada margaritifera assessed by HSV colour quantification

Type Article
Date 2019-05
Language English
Author(s) Stenger Pierre-Louis1, Vidal-Dupiol Jeremie2, Reisser CelineORCID1, Planes Serge3, Ky Chin-Long1
Affiliation(s) 1 : IFREMER, UMR 241 Écosystèmes Insulaires Océaniens, Labex Corail, Centre Ifremer du Pacifique, BP 49, 98725, Tahiti, French Polynesia
2 : IFREMER, UMR 5244 IHPE, University Perpignan Via Domitia, CNRS, University Montpellier, F-34095, Montpellier, France
3 : PSL Research University, EPHE-UPVD-CNRS, USR 3278 CRIOBE, Labex Corail, Université de Perpignan, 52 Avenue Paul Alduy, 66860, Perpignan Cedex, France
Source Scientific Reports (2045-2322) (Springer Science and Business Media LLC), 2019-05 , Vol. 9 , N. 1 , P. 7520 (10p.)
DOI 10.1038/s41598-019-43777-4
Abstract

The bivalve Pinctada margaritifera has the capacity to produce the most varied and colourful pearls in the world. Colour expression in the inner shell is under combined genetic and environmental control and is correlated with the colour of pearls produced when the same individual is used as a graft donor. One major limitation when studying colour phenotypes is grader subjectivity, which leads to inconsistent colour qualification and quantification. Through the use of HSV (Hue Saturation Value) colour space, we created an R package named ‘ImaginR’ to characterise inner shell colour variations in P. margaritifera. Using a machine-learning protocol with a training dataset, ImaginR was able to reassign individual oysters and pearls to predefined human-based phenotype categories. We then tested the package on samples obtained in an experiment testing the effects of donor conditioning depth on the colour of the donor inner shell and colour of the pearls harvested from recipients following grafting and 20 months of culture in situ. These analyses successfully detected donor shell colour modifications due to depth-related plasticity and the maintenance of these modifications through to the harvested pearls. Besides its potential interest for standardization in the pearl industry, this new method is relevant to other research projects using biological models.

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