Heritability estimate for mantle edge pigmentation and correlation with shell pigmentation in the white-shell strain of Pacific oyster, Crassostrea gigas

Abstract

The pacific oyster (Crassostrea gigas) is one of the most widely farmed aquatic animal species and of great economic importance. Mantle edge color in C. gigas is highly variable and considered as a new potential trait for a better commercial value. In this study, heritability for mantle edge pigmentation and its correlation with shell pigmentation were explored in the white-shell strain of C. gigas with mixed-family method. A total of 460 offspring raised under communal conditions were successfully assigned to their parents using four multiplex PCR protocols based on 11 microsatellite loci. Mantle edge pigmentation was measured through assay of melanin content using spectrophotometric analysis. Animal model heritability estimate were 0.215±0.092 for mantle edge pigmentation. The genetic and phenotypic correlations between two pigment traits were 0.980±0.094 and 0.423±0.042, respectively. Pearson analyses for average mantle edge and shell pigmentation of family also showed strong and significant correlation (r=0.729, P=0.000, n=29). Chi-square analyses showed that mantle edge pigmentation of family 7 segregated into “lighter” and “darker” groups in a 3:1 ratio (P=0.833), suggesting that a major locus might control mantle edge pigment trait. The results obtained in this study will benefit selective breeding of C. gigas with desired mantle and shell pigmentation.