Genetic enhancement of Fujian oyster (Crassostrea angulata): Accelerated progeny growth through CRISPR/Cas9-mediated Myostatin-knockout

The growing global demand for aquatic protein underscores the importance of sustainable aquaculture. The Fujian oyster ( Crassostrea angulata ) is a key aquaculture species, yet its market value is constrained by its small size. Gene editing is a good tool for genetic improvement, while Myostatin ( MSTN ) gene has shown a great potential for enhancing growth in aquatic animals, we initiated a MSTN gene editing program in C. angulata . We designed and validated an sgRNA, constructed a CRISPR/Cas9 plasmid, and obtained a best electroporation condition. We then evaluated edited populations through to adulthood. The results showed that oyster gene editing can be completed by the transfection method. Mutant progeny have a normal growth, development, and survival. The mutant progeny has a better growth trait and larger adductor muscle, and their yearling progeny wet weight being over 53.10% greater than that of control group. Interestingly, we observed that mosaicism exhibited dynamic changes during the ontogeny of oysters. In conclusion, we successfully obtained mutant mosaic oyster adult lines for the first time, which provide a source for creating homozygous edited populations. This study establishes a foundation and demonstrates the potential for gene editing-based breeding in shellfish. • The generation of the first gene-edited adult oysters in the Fujian oyster ( Crassostrea angulata ) are generated. • Knockout of Myostatin ( MSTN ) led to mutant progeny that exhibited over 53.10% greater wet weight and larger muscle mass. • Mutant mosaic lines provide biological materials for shellfish homozygous breed development and marker-assisted selection.