Shell color and growth traits share the same major locus in Cyclina sinensis

The clam (Cyclina Sinensis) is an important economic marine mollusk in China. Its shell typically exhibited purple and white colors, with consumers showing a preference for the purple variety. Notably, clams with purple shells are generally larger than those with white shell. Shell color is a qualitative trait, but no evident dominant/recessive relationship has been identified, posing challenges for selecting large, pure purple clams. In this study, we explored genome-wide genetic markers using genotyping by sequencing (GBS) method, and conducted genetic analyses for shell color and growth traits. The results indicated that growth traits were highly correlated both genetically and phenotypically. Two loci associated with clam shell color were identified, and shell color was significantly associated with growth traits, as they share the same major locus. The interactions between these loci suggest potential benefits and utilization methods in breeding practices.