Developing Sugarcane and Energy Cane As Highly Productive Biofactory Platforms

Sugarcane and energy cane, Saccharum spp., are key players in the expanding bioeconomy for sugars, bioenergy, and platform for production of native and recombinant proteins. Saccharum species are ideal for such applications due to their high resource use efficiencies, rapid growth, and efficient photosynthetic pathway, and high biomass production capacity with potential yields of up to 45 Mg of dry biomass per hectare per annum. Our technology platform integrates molecular genetics, genomics and biotechnology to develop new traits through optimized transgene delivery. We have applied this approach in three fundamental research areas: biofuel development, recombinant protein expression and stress tolerance trait development. One major area focuses on the enhancement of biomass yield, fiber content, and water and nutrient use efficiencies for biofuel production. Our current platform focuses on the down regulation of a set of isolated sugarcane genes involved in hormonal biosynthesis, resulting in up to an 81% increase in biomass, and 26% and 95% in total fiber and lignin content, respectively. A second major area is the cost-effective and large-scale commercial recombinant production of high value proteins, achieving up to 10.0 mg recombinant protein/kg of stalk weight or 1.4% of total soluble protein. High protein expression levels in the stalk-based production system are achieved by using our promoter staking expression system and our “in-house” toolbox of sugarcane tissue-regulated promoters for targeted gene expression to vascular tissues. A third major area consists of the development of enhanced traits for tolerance to stresses such as cold, salinity and drought to help broaden sugarcane production in marginal growth environments. Current method development has resulted in enhanced stress tolerance of up to 63% survival after 5 days of cold (10°C), 80% survival at high salt (1 M sodium chloride), and 90% survival and an 11% decrease in water usage after 3 weeks of drought. We are now focusing on optimizing existing methodologies and developing new technologies such as gene editing and targeted mutagenesis to enhance our currently used transgenic technologies to improve sugarcane and energy cane.