Generation of switchgrass plants with optimized biomass composition for biofuel production

Liquid fuel produced from dried plant material (i.e. lignocellulosic biomass such as wood chips, straw, switchgrass, and corn stover) is nearly cost competitive with corn ethanol. Lignocellulosic biomass is the most abundant, readily available, and renewable material on Earth to produce biofuels. However, lignin, a key component of plant material necessary for growth and protection against pathogens and pests, is a very tough substance that prevents accessibility to fermentable sugars present in biomass. Lignification makes biomass processing for biofuels very difficult and expensive. Previous efforts to develop low lignin plants have failed due to weakened stalks and stems and poor growth. In this project, we will validate the combination of two traits (cell-specific low lignin and increased fermentable sugar accumulation) that were successfully proven in model plant organisms. In Phase I, we will develop synthetic biology tools for plant transformation and generate low lignin/high sugar switchgrass transgenic lines. During Phase II, these lines will be extensively characterized for their optimized properties in greenhouse trials, and the best engineering strategies will be selected for field trials for a Phase III effort. Commercial Application and Benefits: This engineering technology will enable healthy switchgrass plants to grow with 20% more fermentable sugars and 40% less lignin (but reduced only in selected internal fiber structures so that stalks and stems remain strong). Consequently, biorefineries using this low lignin switchgrass can reduce their initial investment, lower their ongoing operating expenses, and increase their annual revenue. Low lignin switchgrass would give cellulosic biofuels an economically competitive advantage compared to corn ethanol. This project will demonstrate healthy, low lignin switchgrass if approved for the full Phase I and Phase II. The combined phases are necessary due to the long time required for switchgrass engineering and characterization because plants need to grow to maturity and at least two cycles are required to show that the desired traits are reproducible. Demand for low lignin switchgrass will significantly increase in the next few years. Construction is already underway to expand annual production capacity of cellulosic biofuels from 25 million gallons (ethanol equivalent) in 2012 to over 650 million gallons in 2016. Biorefineries benefit most directly. Farmers benefit from the increased demand and diversity of planting options. Additionally, once the low lignin switchgrass is demonstrated, this technology could be used to enhance the productivity and profitability of other commercial crops such as grazing and forage crops.