Adding value to the biofuel feedstock sugarcane with intragenic and transgenic biotechnologies

Sugarcane is one of the most productive biofuel crops due to its superior photosynthetic efficiency and accumulation of large amounts of sucrose in the stem internodes. Sugarcane has a C4 type metabolism for fixation of carbon, allowing it to be very well adapted to biomass production in tropical and subtropical regions. Genetic improvement of photosynthetic efficiency can be achieved by developing the most photosynthetically effective canopy. We will report on expression or RNAi suppression of a number of candidate genes and their correlation to altered phenotypes and the consequences for photosynthesis.

 We are also exploring the prospects of diverting the carbon flux from sucrose to triacylglycerol (TAG) for increased energy density and development of an advanced biofuel. This strategy involves the analysis of combinations of gene expression cassettes for metabolic engineering, supporting biosynthesis and storage of TAG.  Correlations between TAG accumulation and gene combinations and their expression levels will be presented. These data indicate the feasibility of genetically engineering the high biomass crop sugarcane to produce TAG, which can be readily used as biodiesel transportation fuel.

 In addition to the above transgenic approaches an intragenic approach for herbicide resistance and altered cell wall composition to enhance conversion of lignocellulosic sugarcane residues to biofuel will also be discussed.