Maximizing TAG Accumulation in Plant Leaves by Combinatorial Metabolic Engineering

Supply of vegetable oils as a major commodity faces continuous pressure. Global demand is expected to double in the next two decades due to increasing world population and rising petroleum prices. Limitations on arable land and other inputs mean it may be difficult to meet this additional demand with current oilseed-based production systems.  Consequently, biomass oil has attracted significant attention in recent years as an alternative and sustainable production platform with a myriad of applications ranging from food, fuel to oleochemicals.  Previously, we reported the accumulation of up to 17% and 32% triacylglycerol (TAG) in Nicotiana tabacum and N. benthamiana leaf tissue (dry weight), respectively. This was achieved by a combinatorial metabolic engineering strategy targeting fatty acid biosynthesis (‘Push’), TAG assembly (‘Pull’) and oil accumulation (‘Package’) in plant cells^1,2. In this presentation, we will describe results in stably-transformed Nicotiana tabacum achieved with some of our ‘2^nd generation’ constructs. These include stacking of additional genes and fine-tuning of expression to further augment oil storage in leaf cells. In addition, we will present preliminary phenomics data highlighting the effect of light intensity and day length on the extent of TAG accumulation in leaf tissue as well as recent successes in the engineering of the Nicotiana leaf fatty acid profile.