C1oning, Expression And Function Analysis Of ω-3Fatty Acid Desaturase Gene From Peanut

Polyunsaturated fatty acids (PUFAs) consist of a straight chainof16-22carbon atomswith two or more double bonds. Based onlocalization of the first unsaturated double bond from methyl end of fatty acid molecular, PUFAs are classified into two categories, ω-3fatty acids and omega-6fatty acids. a-linolenic acid (ALA) is an omega-3polyunsaturated fatty acids, which plays a very important role in maintaininging human health, especially, in supporting brain development. ALA can serve as the precursor for EPA and DHA synthesis in humans, and balance the levels ofω-3and of co-6fatty acid. However, ALA (18:3n-3) can not be synthesized by human beings, and it can only be obtained from diets directly.Peanut is one of the four major oil crops in the world, which contains80%oleic acid and linoleic acid. At present, omega-6fatty acid desaturase (FAD2, FAD6) gene of peanuts has been cloned. However, no researches of omega-3fatty acid desaturase of peanuts has been reported. In this research, the main pathway of unsaturated fatty acids biosynthesis were drawn by KEGG (Kyoto Encyclopedia of Genes and Genomes) notation based on transcriptome database PeanutBD eastablished by our lab. FAD8fatty acid desaturase gene was cloned, named AhFAD8, and registered in GeneBank. The analysis and prediction of structure of AhFAD8showed that it had four transmembrane domain and three His-box which was consistent with structural characteristic of desaturase. The expression vector harboring AhFAD8gene was constructed, transformed into Pichia pastoris, and expressed. Fatty acid composition of Pichia pastoris were analyzed through meteorological chromatography. The results showed that the desaturation rate of oleic acid of Pichia pastoris harboring AhFAD8gene was increased25.5%than the conrol, and they were significantly different. These results demonstrated that AhFAD8gene could act as FAD8fatty acid desaturase in yeast.Some important gene for the enzyme of unsaturated fatty acid synthesis in peanut (Baisha1016) and Monodus subterraneus has been explored. Monodus subterraneus is one kind of microalgae with high-yield omega-3PUFAs. On the results of analysised the transcriptome sequences and functional annotation, we got139genes about the biosynthetic pathway of polyunsaturated fatty acids, including omega3, omega6fatty acid desaturase, elongases and some other enzymes in unsaturated fatty acids biosynthesis pathway; Provide a basis to get the full-length functional genes of peanuts and Monodus subterraneus, and laid the foundation for further study of their unsaturated fatty acid synthesis pathway and influencing factors.