Manipulation of photosynthetic carbon metabolism in wheat to improve yield

Ensuring food security is a major challenge given the projected need to increase world food production by 40% in the next 20 years and 70% by 2050 (FAO forecasts). There is clearly an urgent need to develop crop plants that yield higher outputs per unit area of land, without having to increase inputs of fertiliser or water. The aims of this research proposal are to test the hypotheses that: 1) The existing variation in photosynthetic capacity can be exploited to increase photosynthesis and total biomass of modern wheat cultivars; and 2) Genetic manipulation of photosynthetic carbon metabolism can lead to enhanced photosynthetic performance in crop plants and result in higher yields, increased nitrogen use efficiency and increased resource-use efficiency. We will screen existing wheat germplasm from a range of sources using a combination of carbon isotope discrimination, gas analysis and biochemical assays to identify plants with improved photosynthetic characteristics for use in future breeding programmes. We will also produce transgenic wheat plants with altered levels of SBPase and Rubisco. A detailed physiological and molecular analysis of the resulting transgenic lines will be carried out to determine the impact of photosynthetic parameters on growth in greenhouse grown plants.

It has been estimated that increases of 50% will be required in the yield of grain crops such as wheat and rice if food supply is to meet the demands of the increases in population. There is clearly an urgent need to develop crop plants that yield higher outputs per unit area of land, without having to increase inputs of fertiliser or water. The overall aim of this research proposal is to identify plants with improved photosynthetic characteristics. We will take two approaches to address this: 1. Screening Genotypes for superior photosynthetic characteristics: - collection of diverse elite germplasm, likely to vary in photosynthetic performance - identification of varieties in the glass house with different photosynthetic characteristics by determining variation in stomatal and mesophyll conductance using carbon isotope discrimination - identification of varieties in the field with different photosynthetic characteristics by screening for differences in canopy temperature, canopy growth rate and combined measurement of CO2 assimilation and quantum efficiency -detailed characterization of varieties with significantly different properties to assess the relative contribution of RuBP-regeneration and Rubisco activity to CO2 assimilation - selection of lines with superior traits for crossing into similar genetic backgrounds for comparison and further breeding. 2. Genetic manipulation of photosynthesis: - Production of transgenic plants to increase the expression of SBPase and to decrease expression of Rubisco and biolistic nuclear transformation of these constructs into spring wheat - molecular and biochemical characterization of transgenic lines (transgene copy number and zygosity will be assessed using TaqMan PCR; candidate gene transcript abundance by reverse transcriptase PCR; and phenotypic changes by enzyme activity/protein) - physiological characterisation of transgenic lines assessment of photosynthetic and growth parameters

Wheat is the UK's largest crop with an annual production of 14 million metric tons and market values for grain and processed products of approximately £1.4 billion and £14 billion, respectively. Productivity gains can be achieved by genetic gains that increase yield potential. The potential economic impact of a 10% increase in UK wheat production is in excess of £1.5 billion p.a. to the UK economy. Improvements to the efficiency of production can decrease the use of costly resources, such as fossil fuel, water, nitrogen, potassium and phosphorus. The proposed research will improve the economic livelihoods of UK farmers whilst safeguarding the environment. The secure supply of affordable and safe food is of direct societal and political importance to the UK population. A strong agriculture sector is particularly important in developing regions where it makes a major contribution to the economy and to the competiveness of agrochemical and breeding companies. It is however also recognised that the results from this project may have implications on a more global scale, although this will not be realised within the time frame of the project. In the longer term the programme will have the potential to directly benefit developing countries where more than 1 billion people are currently facing starvation. Increased food security will help provide social stability and decrease problems associated with social unrest and mass migration. It will further add to the huge research efforts undertaken by regional international centers specializing in agriculture. In turn, the project will also benefit the UK science base and promote the UK's international co-operation initiatives. The work is directly relevant to agriculture: the farming community, the ag-biotech industry and breeding companies in the private sector will be major beneficiaries. Represenatives from these companies will be invited onto the steering committee for this programme. Information exchange with the wider ag-biotech and breeding community and with downstream stakeholders will be maintained through academy-industry outreach activities in programmes such as WGIN and Monogram. We will take full advantage of the opportunities offered by CIRC to expand our contacts with UK breeders and will appoint a stakeholder advisory group to increase the impact of the research. Potential intellectual property will be identified and properly protected through the commercialisation offices of both host sites, in consultation with CIRC. Non-patentable findings will be disseminated to the scientific community through conference presentations and peer-reviewed publications and to the wider public through the media, national and local events. In addition, the PIs and PDRAs will speak at international conferences selected on the basis of likely attendance by agri-business representatives.