Location: Plant Physiology and Genetics ResearchTitle: Oil accumulation in leaves directed by modification of fatty acid breakdown and lipid synthesis pathways Author
Submitted to: Plant Biotechnology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2009
Publication Date: 8/4/2009
Citation: Slocombe, S.P., Cornah, J., Pinfield-Wells, H., Soady, K., Zhang, Q.Y., Gilday, A., Dyer, J.M., Graham, I.A. (2009). Oil accumulation in leaves directed by modification of fatty acid breakdown and lipid synthesis pathways. Plant Biotechnology Journal,7:694-703. Interpretive Summary: Modern society is heavily dependent on fossil oil as a source of fuel and industrial feedstocks. In light of decreasing availability of oil, volatility in price, and negative impacts on the environment, there is a clear and present need to develop alternative, domestically produced, and environmentally friendly fuels and chemical feedstocks. Biofuels such as ethanol and biodiesel represent an important component in the portfolio of alternatives that will help meet energy demands, but the production of second generation biofuels such as cellulosic ethanol remains a challenge. Plant oils are easier to process into biofuels (e.g., biodiesel), but the total yield of oil (which is produce only in the seeds of plants) is far below the demand from the energy and food/feed markets. In this manuscript, we describe a novel method for producing plant oils in above-ground plant biomass. The yield of plant biomass is significantly greater than the yield of seeds, and the ability to produce even small amounts of oil in plant biomass could significantly transform the landscape for biofuels production. For instance, production of just 2% oil in the leaves of Miscanthus would translate to a yield of over 0.6 tons of oil per hectare, which is on par with the amount of oil obtained from a hectare of soybeans. The production of both biodiesel and cellulosic-ethanol feedstocks from a single crop is attractive for many reasons including efficiency of land and water usage, a reduction in competition between food and energy markets, and increased economic viability of biorefining due to capture of multiple high-value products.
Technical Abstract: Plant oils in the form of triacylglycerol (TAG) are used for food, industrial feedstock and biofuel manufacture. TAG is typically harvested from the fruit or seeds of oil crop species. Plants can also accumulate small amounts of TAG in the leaves and other vegetative tissues. Here we show that leaf TAG levels can be increased significantly (10-20 fold) by blocking fatty acid breakdown, particularly during extended dark treatments or leaf senescence in the model plant Arabidopsis. We compared this with the accumulation of TAG in leaves ectopically expressing LEC2, a seed development transcription factor involved in storage product accumulation and found that TAG accumulation also occurred during leaf senescence. This work raises the possibility of producing significant amounts of oil in vegetative tissues of biomass crops such as Miscanthus.