Metabolic Engineering for Increasing Oil in Vegetative Plant Tissues

The seed oils of plants are extensively utilized for food and fuel, and the demand for plant oils will only increase as world population continues to grow. Our lab is striving to engineer metabolic processes in plants to enhance accumulation of the storage lipid triacylglycerol (TAG) in vegetative tissues, with the end-goal of massively increasing the amounts of oil that can be recovered from plants. The rationale is that the biomass of plant vegetative tissues is far greater than that of seeds, and thus production of high amounts of the energy dense TAG in a plant’s vegetative biomass represents a very promising way to generate sustainable and economically-viable sources of vegetable oil. The goal of this project was to evaluate different genetic tools for improving TAG levels in A. thaliana leaf tissues by affecting different aspects of TAG metabolism including synthesis, packaging and turnover. Toward this end, we utilized A. thaliana mutant lines deficient in TAG turnover (pxa1 and cgi58) as a starting point for introducing genes encoding enzymes and structural proteins involved in TAG biosynthesis and compartmentation. The results of these studies reveal specific genotype and transgene combinations that are most favorable for increasing oil in leaves, as well as provide additional insights to gene functions in TAG metabolism. Implications for producing biofuels and high value industrial chemicals are discussed.