Field production, purification and analysis of high-oleic acetyl-triacylglycerols from transgenic Camelina sativa

A diacylglycerol acetyltransferase, EaDAcT, from Euonymus alatus, synthesizes sn-3 acetyl triacylglycerols (acetyl-TAG) when expressed in Arabidopsis, Camelina and soybean. Compared to most vegetable oils, acetyl-TAGs have reduced viscosity and improved cold temperature properties that confer advantages in applications as biodegradable lubricants, food emulsifiers, plasticizers, and 'drop-in' fuels for some diesel engines. A high-oleic Camelina line was engineered to express the EaDAcT gene in order to produce acetyl-TAG oils with fatty acid compositions and physiochemical properties complementary to wild-type acetyl-TAG. The accumulation of acetyl-TAGs at 70 mol% of seed TAG in field-grown high-oleic Camelina had minor or no effect on seed weight, oil content, harvest index and seed yield. The total moles of TAG increased up to 27% reflecting the ability to synthesize more acetyl-TAG from the same supply of long-chain fatty acid. Acetyl-TAG could be separated from long-chain TAG by silica column or by reverse phase chromatography. The predominant acetyl-TAG molecular species produced in high-oleic Camelina was acetyl-dioleoyl-glycerol. The crystallization temperature of high-oleic acetyl-TAG (by differential scanning calorimetry at 1.0 °C/min) was reduced by 30 °C compared to control TAG. The viscosity of high-oleic acetyl-TAG was 27% lower than TAG from the high-oleic control and the caloric content was reduced by 5%. Field production of T4 and T5 transgenic plants yielded over 250 kg seeds for oil extraction and analysis.