Abstract
Long-chain polyunsaturated fatty acids (LC-PUFAs) are crucial for human health and cannot be produced internally. Bivalves, such as oysters, serve as valuable sources of high-quality PUFAs. The enzyme fatty acid desaturase (FADS) plays a key role in the metabolism of LC-PUFAs. In this study, we conducted a thorough genome-wide analysis of the genes belong to the FADS family in Crassostrea gigas and Crassostrea angulata, with the objective of elucidating the function of the FADS2 and investigating the genetic variations that affect PUFA biosynthesis. We identified six FADS genes distributed across four chromosomes, categorized into three subfamilies. The coding region of FADS2 revealed five non-synonymous mutations that were shown to influence protein structure and stability through molecular dynamics simulations. The promoter region of FADS2 contains ten SNPs and three indels significantly correlated with PUFA content. These genetic variations may explain the differences in PUFA levels observed between the two oyster species and could have potential applications in enhancing PUFA content. This study improves the molecular understanding of PUFA metabolism in oysters and presents a potential strategy for selecting oysters with high PUFA levels.