Manipulation of lignin in the energy grass Miscanthus

Supervisor: Dr Iain Donnison

The Institute is one of the participants in the Biomass, Biofuels and Energy Crops consortium funded by the EPSRC SuperGen initiative (http://www.supergen-bioenergy.net/) and this project is funded by this grant.

Ambitious targets have been set internationally to reduce CO2 emissions and increase renewable sources of energy. Meeting these targets will require a large increase in the use of bioenergy, particularly in the case of transport fuels where bioenergy crops are the only realistic short to medium term option. Current 'first generation' annual food crops such as oilseed rape, maize and wheat being used for energy production have a poor energy balance when the entire lifecycle is considered. Indeed, it has been argued that biofuels from annual crops will lead to more expensive food and fuel for very little gain in terms of reducing CO2 emissions. Future 'second generation' energy crops will need to be higher yielding with lower inputs thereby providing a sustainable method of generating energy and greatly reducing CO2 emissions. Dedicated perennial energy crops generate high yields over successive generations with minimal requirements for energy-demanding nitrogen fertilizers. However the potential of dedicated crops such as energy grasses is limited because plant varieties have not been selected for this purpose. There are distinct challenges to determine and improve quality traits to increase ultimate energy yields. Perennial grasses such as Miscanthus offer the potential to be utilised through either thermal or biological conversion methods to generate heat, electricity or transport fuels. The route chosen being largely determined by the calorific value, moisture content and the availability of carbohydrates. Chemical composition, particularly of the cell wall, underlies these characteristics and can be measured to associate phenotype to genotype. To radically alter the composition of energy crops it is necessary to take a biotechnological approach. Such an approach can demonstrate the role of a gene (i.e. functionally test), and can provide valuable research material to test the impact of manipulations on conversion yields and efficiency. Lignin is a good initial target for such an approach because the target genes have already been identified in model species. Furthermore it is known that when manipulated these genes are highly likely to alter lignin composition, for example the brown midrib phenotypes of maize which is a close relative of Miscanthus. The proposal is therefore to identify the full length sequences for target genes in Miscanthus. These gene sequences will be cloned into plant transformation vectors for enhanced and down regulation of the gene. Transformed plants will be characterised for the impact on gene expression and biochemical phenotype. Material with highly altered lignin composition will then be tested for the effect on conversion yields and efficiency including the effect on fast pyrolysis to bio-oil and gasification of biomass.