Expression of Umbelopsis ramanniana DGAT2A in Seed Increases Oil in Soybean

Abstract

Oilseeds are the main source of lipids used in both food and biofuels. The growing demand for vegetable oil has focused research toward increasing the amount of this valuable component in oilseed crops. Globally, soybean (Glycine max) is one of the most important oilseed crops grown, contributing about 30% of the vegetable oil used for food, feed, and industrial applications. Breeding efforts in soy have shown that multiple loci contribute to the final content of oil and protein stored in seeds. Genetically, the levels of these two storage products appear to be inversely correlated with an increase in oil coming at the expense of protein and vice versa. One way to overcome the linkage between oil and protein is to introduce a transgene that can specifically modulate one pathway without disrupting the other. We describe the first, to our knowledge, transgenic soy crop with increased oil that shows no major impact on protein content or yield. This was achieved by expressing a codon-optimized version of a diacylglycerol acyltransferase 2A from the soil fungus Umbelopsis (formerly Mortierella) ramanniana in soybean seed during development, resulting in an absolute increase in oil of 1.5% (by weight) in the mature seed.

AtABCA9 transporter supplies fatty acids for lipid synthesis to the endoplasmic reticulum

“…Overexpression of acetyl-CoA carboxylase or fatty acid synthase had little effect on the level of lipid accumulation (23,24), whereas overexpression of enzymes catalyzing TAG biosynthesis, such as glycerol-3-phosphate acyltransferase, lysophosphatidic acid acyltransferase, and diacylglycerol acyltransferase, significantly increased seed oil yield, by 10-40% (25)(26)(27)(28)(29). Overexpression of the transcription factor WRINKLED1 also increased seed oil yield by 20% (30).…”

Phospholipase Dζ Enhances Diacylglycerol Flux into Triacylglycerol

“…Thus the role of the PLD z enzyme may be to increase the available substrate for TAG production. Along with a limited number of descriptions of significantly enhanced TAG in oilseeds (Lardizabal et al, 2008; Weselake et al, 2009; Oakes et al, 2011), this study suggests that the last steps in TAG biosynthesis are bottlenecks to its production. By converting PC to DAG more effectively, PLD z may enhance DGAT activity for TAG production in Camelina seeds.…”

Highlights of recent progress in plant lipid research

“…Notably, the increase in seed oil content did not affect protein content (a major high-value co-product from soybean), and therefore represents an economic boon of several billion dollars per year for the soybean industry [7].…”