Molecular cloning, expression pattern of β-carotene 15,15-dioxygenase gene and association analysis with total carotenoid content in pearl oyster Pinctada fucata martensii

beta-carotene-15,15-dioxygenase is an enzyme involved in carotenoid metabolism to catalyze oxidative cleavage of beta-carotene at its central double bond to two molecules of retinal in intestinal cells of vertebrate. In this study, we cloned and characterized beta-carotene-15,15-dioxygenase in pearl oyster Pinctada fucata martensii (Pm beta CDOX). The full length of Pm beta CDOX gene was 1802 bp, including 1554 bp of the open reading frame (ORF) that encoded 517 amino acids, a 5'UTR of 134 bp and a 3' UTR of 114 bp. Pm beta CDOX was expressed at various tissues with highest level in hepatopancreas. Eighteen and fifteen single nucleotide polymorphisms (SNPs) were separately obtained in the exon and promoter of Pm beta CDOX. Eight SNPs (six SNPs in the exon and two SNPs in the promoter region) were significantly associated to total carotenoid content (TCC) (P < .05). The eight SNPs of significantly associated TCC were divided three haploblocks. Haplotypes CCTT had larger TCC than other haplotypes. The present results suggest that Pm beta CDOX is involved in carotenoid metabolism in pearl oyster. Our study will be helpful for development gene marker in selective breeding programs for TCC trait of the species.