Mendelian inheritance of orange shell color in the Pacific oyster Crassostrea gigas

The oyster shell color has become an important factor influencing consumer choice. Understanding the genetic basis of shell colors is important in oyster genetic breeding. In this study, we investigated the inheritance of the orange shell color trait in the Pacific oyster. The oysters with orange shell color were generated in our breeding studies that has never been observed in natural population. It is a novel mutant trait in the Pacific oyster. In this study, we investigated the inheritance of the orange shell color trait crossing the orange variant with two other color variants (white and black). The shell color morph was determined for each in 27 first- and 12 s-generation crosses as well as 13 test crosses. We found that the orange shell color is recessive trait compared to black and white, and is determined by two independent recessive genes. In addition, our data revealed that the genetic loci controlling orange shell have no effects on the formation of black foreground pigment. The information obtained in this study could guide the breeding program for desired shell color in pacific oyster.