Posterior saibo selection in the Japanese pearl oyster, Pinctada fucata martensii, as a non-genetic approach to producing high-quality cultured pearls

This study evaluates the repeatability of saibo selection influence on pearl quality in Pinctada fucata martensii, focusing on posterior saibo as a non-genetic approach to enhance pearl attributes. Saibo tissue from anterior, middle, and posterior mantle regions of donor oysters was grafted into 90 recipient oysters, with pearls cultured for 6 months in Ago Bay. Pearls were classified into quality categories (low, medium, high) and analyzed for luster, interference color, yellowness index (YI), whiteness index (WI), nacre thickness, irregular and organic layer thicknesses, nacre tablet thickness, and surface nacre tablet area. Results showed that middle and posterior saibo groups did not exhibit significant differences in total nacre thickness, but both had significantly thicker nacre layers compared to the anterior group (p < 0.05). The posterior group exhibited thinner irregular (23.54 ± 2.86 µm) and organic layers (30.31 ± 6.66 µm, p < 0.001) and larger surface tablet areas (6.104 ± 0.115 µm, p < 0.001). Luster (0.112 ± 0.003) and interference color (0.123 ± 0.005, p < 0.001) were significantly higher in posterior-derived pearls. Random forest analysis identified luster as the most critical quality predictor, while structural equation modeling confirmed negative impacts of irregular layer thickness (− 0.27*, p < 0.05) and organic layer thickness (− 0.4***, p < 0.001) on luster. This study confirms that posterior saibo consistently yields high-quality pearls, validating the repeatability of this method. This sustainable, non-genetic approach aligns with industry needs, reducing reliance on genetic modification. Future research should explore environmental factors to optimize this method further, ensuring reliable, high-quality pearl production.