Understanding and exploiting the diversity of form in Miscanthus

In order to tackle the problem of climate change, and address the challenge of atmospheric CO2 abatement, sustainable technologies must be developed and introduced. One of these technologies involves the use of energy crops to replace coal, oil and natural gas in direct combustion, gasification, biodiesel production, and fermentation to alcohols. The advantage of biomass over fossil fuels is that combustion releases only the carbon taken up during growth, and so the energy generated is carbon neutral. The UK government aims to generate 10% of energy from biomass by 2010 to help achieve it's obligations under the Kyoto Climate Change Agreement. Moreover biomass is the only renewable capable of providing liquid transport fuels and green chemicals and there is a UK target of 5% of transport fuels to be renewable by 2010. Miscanthus is a giant perennial grass with excellent characteristics for a biomass crop in Northern Europe as it combines rapid growth with tolerance to low temperatures. Once established, it requires minimal fertiliser input and has excellent disease resistance whilst producing a high yield of biomass annually. However a fundamental understanding of the growth and development in Miscanthus is lacking because it is a novel crop for Europe, and is now needed. Preliminary research has identified several plant characteristics of interest in relation to yield and quality of biomass. For example, plant size and shape are of paramount importance, in particular the relationship between stem diameter and height. These characteristics are already known to be readily measurable and under genetic control, and are therefore open to improvement by crop breeding. Biomass yield is directly correlated with plant height, and stem diameter is also an important character to prevent plants falling over. Currently, the most commonly planted energy crop is Miscanthus x giganteus, a naturally occurring hybrid between Miscanthus sinensis and Miscanthus sacchariflorus. The two parent species display contrasting forms: Miscanthus sinensis is compact with numerous stems while Miscanthus sacchariflorus is tall with few stems. IGER has a unique collection of Miscanthus, the most comprehensive in Europe, which includes plants with very different forms that can be used to identify the genes responsible for characteristics such as stem height and thickness. Miscanthus takes three years to become fully established, so the use of DNA sequences to predict the mature plant characteristics would greatly speed up the breeding process to increase biomass yield. This project aims to develop suitable sequences and use them to understand what controls growth and form in Miscanthus, and hence assist the breeding programme.

To identify the genes which control plant morphological characteristics in Miscanthus, a wide genetic cross will be used to generate a mapping family to allow identification of QTL associated with traits such as plant height and stem diameter. This trait map will be complemented by a genetic map based on publicly available SSR markers from closely related species and a small number of markers which are available for Miscanthus in order to associate genotype with phenotype. For example, genes identified as candidates for traits of interest will be mapped to test for association with QTL and the allelic variation present in the IGER collection of >250 accessions will be studied. QTL regions to which no known genes associate will be sequenced by exploiting physical maps in related species and a Miscanthus BAC library. Alleles responsible for favourable phenotypes will be identified for use as molecular markers in marker assisted selection (MAS) at an early stage of plant development. The proposed research programme is to: 1. Screen the extensive Miscanthus germplasm collection at IGER to identify individuals divergent in morphological characteristics. 2. Generate a mapping family to identify QTL associated with stem height, diameter and number. 3. Create a genetic map using sugarcane, Sorghum and maize SSR markers especially targeted at the relevant regions of the genome. 4. Ascertain synteny in relevant regions of the genome between Miscanthus and rice and in the future Brachypodium, maize and Sorghum. 5. Identify morphology-associated candidate genes of interest and map them. 6. Clone and sequence genes of interest using a Miscanthus BAC library 7. Compare genes of interest in Miscanthus to related and model species to understand what makes a giant perennial grass develop the way it does. 8. Associate genotype with phenotype in a range of Miscanthus accessions and develop markers for alleles encoding favourable traits to be used in MAS.