Beyond static metabolic maps - Understanding the cellular organization and dynamics of lipid flux for enhanced seed oil production

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Plant oils are a valuable renewable resource of reduced carbon (fatty acids) used for food, fuels, and chemicals (plastics, paints, cosmetics, etc.). To meet the rising demand of an increasing human population for plant oils will require increased oil production and optimization of plant oil fatty acid compositions for societal applications. Current knowledge indicates that plant oil biosynthesis overlaps with essential membrane lipid production required for cellular function. This research is elucidating how plants balance accumulation of oil with synthesis of membrane lipids so that crop breeding and plant bioengineering efforts can optimize plant oil production without affecting the properties of biological membranes. The project uses genetic mutants, overexpression lines, protein localization and dynamic interactions, in vivo isotopic labeling, and mathematical modeling of non-stationary flux to produce a quantitative description of lipid metabolic network function and dynamics. New engineering strategies based on project results may provide alternative sources of nutritionally valuable food oils, or chemically reactive lipids that can functionally replace petroleum in chemical syntheses. Project results could also lead to the development of new value-added crops that can reinvigorate low-income rural farming communities. This project collaborates with the EXploring College Emerging Leaders (EXCEL) program at Washington State University that seeks to increase participation of Native American communities in STEM subjects. The three postdoctoral scientists, one post bachelor researcher, and multiple undergraduate students are being trained in scientific research and outreach to become the next generation of scientific leaders who will face future scientific challenges and enhance agricultural output for societal gain. Valuable plant oils and essential membrane lipids are assembled by an overlapping metabolic network. The path of fatty acid flux through the network ultimately determines the final oil fatty acid composition, yet how plants control fatty acid flux through this network of lipid assembly is unknown. An important particular unknown is how plants control the use of key intermediates (diacylglycerol) between membrane and oil biosynthesis. This research leverages the expertise of a multi-disciplinary team to elucidate lipid metabolic network structure, fluxes, and sub-cellular spatial organization. A combination of genetic mutants, over-expression lines, protein localization and dynamic interactions, in vivo isotopic labeling, and mathematical modeling is used to develop a quantitative description of lipid metabolic network function and dynamics. This quantitative picture includes the cellular organization and the enzymatic control of fatty acid flux through different branches of the lipid metabolic network that affect seed oil accumulation and composition. The knowledge gained will result in a paradigm shift beyond the current network descriptions of static metabolites that have previously been used to develop bioengineering strategies. In vivo isotopic labeling-based metabolic flux maps enhance the quantitative and dynamic understanding of lipid network function and enable improved engineering efforts. The project also provides important new tools to help guide the design of better metabolic engineering (or targeted breeding) strategies to meet the plant oil needs of the future.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.