Production of Seed-Like Storage Lipids and Increase in Oil Bodies in Corn (Maize; Zea mays L.) Vegetative Biomass

Triacylglycerides (TAGs) are high energy density lipids with a $25 billion commodity at international level. Plant TAGs are produced via a series of chemical reactions catalyzed by certain enzymes including diacylglycerol acyltransferases (DGATs) and phospholipid diacylglycerol acyltransferases (PDATs). In Arabidopsis, certain transcription factors including Wrinkled 1 (Wril) and Leafy Cotyledons2 (LEC2) supply the necessary substrates for synthesis of fatty acids and/or for packaging of the oil bodies. TAGs will be stored as oil body structurs which certain proteins such as oleosin can protect them from Enzymatic degradation. In this Study, we overexpressed three major genes involved in the TAG biosynthesis and accumulation; 1) dgatl as a key enzyme in TAGs biosynthesis, 2) wril which is the major transcription factor involved in supplies of fatty acids for TAG biosynthesis, and 3) oleosin (Ole) gene which encodes for protein that protects TAGs from degradation. All three genes were integrated in maize genome under a constitutive promoter to allow the production of oil bodies and seed storage oil-like TAG in maize vegetative biomass. Our results indicated an increase in the total leaf oil contents by 79% in the metabolically engineered line. GC-MS analysis detected a total of 13 fatty acids in the leaf oil extract samples, representing similar to 99.99% of the total fatty acids. Overall, the percentage of the leaf total saturated (SFA) were decreased while the percentage of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) were increased in metabolically engineered plant leaves. This is the first report of increasing TAG accumulation in maize vegetative biomass (stover) via metabolic engineering, which will open new dimension for creating new opportunities to complement and expedite the cellulosic biofuels applications.