Characteristics of high α-linolenic acid accumulation in seed oils

Modern diets are often deficient in ω-3 fatty acids and additional dietary sources of ω-3 fatty acids are useful. In order to investigate the molecular basis of the high accumulation of the ω-3 fatty acid, α-linolenic acid (18:3), in three different plants, flax (Linum usitatissimum), Dracocephalum moldavica, and Perilla frutescens ω-3 desaturase activity, transcript levels, and 18:3 in-vivo synthesis were examined. The 18:3 content was found to be higher at the later developmental stage of D. moldavica (68%) compared with P. frutescens (59%) and flax (45%) cotyledons. The 18:3 and 18:2 contents in both PC and TAG were determined during various stages of seed development for all three plants in addition to soybean (Glycine max). Northern blot analysis data of three different stages of D. moldavica, flax, and P. frutescens compared with moderately low 18:3 producers, soybean (Glycine max), and Arabidopsis thaliana and Brassica napus, (8-10% 18:3) at a stage of zygotic embryo development of high triglyceride synthesis showed that ω-3 desaturase mRNA levels were higher in all three high 18:3 producers, flax, D. moldavica and P. frutescens. This indicates that the high level of α-linolenic acid in TAG may be largely controlled by the level of ω-3 desaturase gene expression. However, the PC versus TAG fatty acid composition data suggested that along with ω-3 desaturase other enzymes also play a role in 18:3 accumulation in TAG, and the high accumulators have a selective transfer of α-linolenic acid into TAG.