QTL identification for growth-related traits using a high-density bin-map in Pacific oyster (Crassostrea gigas)

Growth is an important economic trait in animal genetics and breeding. The Pacific oyster (Crassostrea gigas) is the major cultured species of oyster in global aquaculture, yet the genetic underpinnings associated with growth have not been fully elucidated. In this study, a high-density genetic map was constructed using a F₂ progeny with different growth rates, and then QTL mapping for seven growth-related traits were performed. The map consisted of 2465 bin markers (461,572 SNP loci) spread across 10 linkage groups within a total genetic coverage of 1117.16 cM and an average density of 0.45 cM. Ten QTLs related to shell length, shell width, total weight, shell weight and soft tissue weight were identified to be distributed on three different linkage groups, and 101 candidate genes were annotated. We found that some candidate genes have been known to be linked to energy metabolism, biomineralization, lipid metabolism, cellular growth and so on. This linkage map and QTLs for important economic traits of C. gigas will be a powerful tool for both fine-scale QTL mapping and marker-assisted selection.