The synthesis and accumulation of stearidonic acid in transgenic plants: a novel source of 'heart-healthy' omega-3 fatty acids.
Dietary omega-3 polyunsaturated fatty acids have a proven role in reducing the risk of cardiovascular disease and precursor disease states such as metabolic syndrome. Although most studies have focussed on the predominant omega-3 fatty acids found in fish oils (eicosapentaenoic acid and docosahexaenoic acid), recent evidence suggests similar health benefits from their common precursor, stearidonic acid. Stearidonic acid is a Delta6-unsaturated C18 omega-3 fatty acid present in a few plant species (mainly the Boraginaceae and Primulaceae) reflecting the general absence of Delta6-desaturation from higher plants. Using a Delta6-desaturase from Primula vialii, we generated transgenic Arabidopsis and linseed lines accumulating stearidonic acid in their seed lipids. Significantly, the P. vialiiDelta6-desaturase specifically only utilises alpha-linolenic acid as a substrate, resulting in the accumulation of stearidonic acid but not omega-6 gamma-linolenic acid. Detailed lipid analysis revealed the accumulation of stearidonic acid in neutral lipids such as triacylglycerol but an absence from the acyl-CoA pool. In the case of linseed, the achieved levels of stearidonic acid (13.4% of triacylglycerols) are very similar to those found in the sole natural commercial plant source (Echium spp.) or transgenic soybean oil. However, both those latter oils contain gamma-linolenic acid, which is not normally present in fish oils and considered undesirable for heart-healthy applications. By contrast, the stearidonic acid-enriched linseed oil is essentially devoid of this fatty acid. Moreover, the overall omega-3/omega-6 ratio for this modified linseed oil is also significantly higher. Thus, this nutritionally enhanced linseed oil may have superior health-beneficial properties.
Ruiz-López
Noemí
N
Department of Biological Chemistry, Rothamsted Research, Harpenden, Herts, UK.
Haslam
Richard P
RP
Venegas-Calerón
Mónica
M
Larson
Tony R
TR
Graham
Ian A
IA
Napier
Johnathan A
JA
Sayanova
Olga
O
D002849:Chromatography, Gas; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000502:physiology; D015525:Fatty Acids, Omega-3 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D008043:Linseed Oil / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism; D017962:alpha-Linolenic Acid / Q000378:metabolism
D015525:Fatty Acids, Omega-3; D014280:Triglycerides; D017962:alpha-Linolenic Acid; D008043:Linseed Oil; D044943:Fatty Acid Desaturases; C062895:stearidonic acid