High accumulation of γ-linolenic acid and Stearidonic acid in transgenic Perilla (Perilla frutescens var. frutescens) seeds

Abstract

Background Polyunsaturated fatty acids such as linoleic acid (LA) and α-linolenic acid (ALA) are abundant in vegetable oils and are important for human health. In the body, LA and ALA are respectively converted to the omega-6 fatty acid γ-linolenic acid (GLA) and the omega-3 fatty acid stearidonic acid (SDA) by Δ6 desaturase (D6DES). Currently, dietary GLA and SDA are mainly obtained from marine organisms, but given their benefits to human health, many studies have aimed to enhance their accumulation in transgenic crops. Perilla frutescens (perilla) accumulates more ALA in its seed oil compared to other oilseed crops, making it a good candidate for the production of fatty acids via the fatty acid desaturase D6DES. Results In this study, we cloned the D6DES gene from Phytophthora citrophthora and confirmed its function in budding yeast. We then transformed the functional D6DES gene under the control of the seed-specific vicilin promoter into the perilla cultivar Yeobsil. The resulting transgenic perilla seeds accumulated significant levels of GLA and SDA, as well as putative C18:2Δ 6,9 at minor levels. Developing seeds and leaves also accumulated GLA and SDA, although PcD6DES expression and GLA and SDA levels were much lower in leaves compared to developing seeds. GLA and SDA accumulated in both polar lipids and neutral lipids in mature perilla seeds expressing PcD6DES , especially in neutral lipids. Although the seed weight in PcD6DES perilla was 87–96% that of wild type, the total oil content per seed weight was similar between lines. The PcD6DES perilla plants contained very high content (over 45%) of both GLA and SDA in seed oil. Conclusions Thus, PcD6DES perilla plants may represent a feasible alternative to traditional marine sources for the production of omega-3 oil capsules and to evening primrose seed oil for GLA as health food. In addition, these plants can be used to create other transgenic lines harboring additional genes to produce other desirable fish-oil like oils. Electronic supplementary material The online version of this article (10.1186/s12870-019-1713-2) contains supplementary material, which is available to authorized users.

Integrative iTRAQ-based proteomic and transcriptomic analysis reveals the accumulation patterns of key metabolites associated with oil quality during seed ripening of Camellia oleifera

“…Our results are in accordance with the findings in coix seed oil, suggesting that perhaps a similar regulatory mechanism is involved 67 . In addition, α-linolenic acid, which can attenuate a variety of inflammatory reactions, is typically consumed as part of a dietary supplement 68 . Reportedly, LOX as a major substrate takes part in the α-linolenic acid metabolic pathway and can catalyze linoleate oxidation in higher plants 69 .…”

Improved SDA Production in High Lipid Accumulating Strain of Mucor circinelloides WJ11 by Genetic Modification

“…Overexpression of fad3 gene did not affect the metabolic pathway to produce major fatty acids by M. circinelloides WJ11. The fatty acids, 16:0, 18:0, 18:1, 18:2 (LA) and 18:3 (GLA), were found as the major lipids before and after overexpression of this gene (Khan et al, 2019b;Yazawa et al, 2007;Lee et al, 2019). The natural sources, such as the plants, algae and fungi, produce SDA as a metabolic intermediate during the biosynthesis of long chain ω-3 fatty acids; It was not found to be accumulated substantially in any species (Whelan, 2009).…”

“…SDA production in plant sources is still in progress in comparison to microbial origin. Scientists cloned the D6D gene from Phytophthora citrophthora and overexpressed in Perilla frutescens and the accumulation of GLA and SDA was over 45% (Lee et al, 2019). But the unavailability of genomic information kept scientists apart to understand the molecular basis of SDA accumulation in this plant (Sreedhar et al, 2017).…”

Rare fatty acids and lipids in plant oilseeds: occurrence and bioactivity

“…Large-scale production of γ-linolenic acid to satisfy the high demand for industrial applications has been achieved with genetically engineered plant sources such as Brassica napus L., B. juncea L., Perilla frutescens L. and Carthamus tinctorius L. varieties expressing the genes for Δ12 and Δ6 desaturases thus driving the synthesis of fatty oils containing 30-40% γ-linolenic acid (Hong et al 2002;Nykiforuk et al 2012;Lee et al 2019).…”