Manipulation of photosynthetic carbon metabolism in wheat to improve yield

Lead Research Organisation: Rothamsted Research
Department Name: Plant Biology & Crop Science

Abstract

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.

Technical Summary

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

Planned Impact

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.

Publications

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Andralojc PJ (2018) Increasing metabolic potential: C-fixation. in Essays in biochemistry

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Carmo-Silva E (2015) Optimizing Rubisco and its regulation for greater resource use efficiency. in Plant, cell & environment

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Driever SM (2017) Increased SBPase activity improves photosynthesis and grain yield in wheat grown in greenhouse conditions. in Philosophical transactions of the Royal Society of London. Series B, Biological sciences

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Hawkesford M (2013) Prospects of doubling global wheat yields in Food and Energy Security

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Jin K (2013) How do roots elongate in a structured soil? in Journal of experimental botany

 
Description Increasing photosynthesis in wheat has been identified as an approach to enhance crop yield, with manipulation of key genes involved in electron transport and the Calvin cycle as one avenue currently being explored. However, natural variation in photosynthetic capacity is a currently unexploited genetic resource for potential crop improvement. Using gas-exchange analysis and protein analysis, the existing natural variation in photosynthetic capacity in a diverse panel of 64 elite wheat cultivars grown in the field was examined relative to growth traits, including biomass and harvest index. Pre-anthesis and post-anthesis photosynthetic traits correlated significantly and positively with grain yield and harvest index. These traits included net CO2 assimilation measured at ambient CO2 concentrations and a range of photosynthetic photon flux densities, and traits associated with the light response of photosynthesis. In most cultivars, photosynthesis decreased post-anthesis compared to pre-anthesis, and this was associated with decreased Rubisco activity and abundance. Heritability of photosynthetic traits suggests that phenotypic variation can be used to inform breeding programmes. Specific cultivars were identified with traits relevant to breeding for increased crop yields in the UK: pre-anthesis photosynthesis, post-anthesis photosynthesis, light response of photosynthesis and Rubisco amounts. The results indicate that flag leaf longevity and operating photosynthetic activity in the canopy can be further exploited to maximise grain filling in UK bread wheat.
Additionally to increase photosynthesis in wheat, the level of the Calvin-Benson cycle enzyme sedoheptulose-1,7-biphosphatase (SBPase) has been increased through transformation and expression of a Brachypodium dystachion SBPase gene construct. Transgenic lines with increased SBPase protein levels and activity were grown under glasshouse conditions and showed enhanced photosynthesis and increased total biomass and dry seed yield. This showed the potential of improving yield potential by increasing photosynthesis in a crop species such as wheat.
Exploitation Route Traits related to photosynthetic performance could be exploited in breeding programmes.

The transgenic lines generated in this project which had increased yields under glass house conditions are being used in a new IWYP grant which has plans to test the lines under UK field conditions
Sectors Agriculture, Food and Drink

 
Description Findings from the project have been shared through CIRC with the UK wheat breeders who can now screen for variation to develop improved wheat cultivars. Transgenic wheat lines generated in the project will be used in an IWYP project which includes plans to undertake a field trail in the UK
First Year Of Impact 2015
Sector Agriculture, Food and Drink
Impact Types Societal,Economic

 
Description BBSRC/IWYP
Amount £695,000 (GBP)
Funding ID BB/N021045/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 01/2016 
 
Description Bilateral NSF/BIO-BBSRC Synthesis of Microcompartments in Plants for Enhanced Carbon Fixation
Amount £1,400,000 (GBP)
Funding ID BB/N016009/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 12/2016 
End 11/2020
 
Description IWYP -Wider and faster: high-throughout phenotypic exploration of novel genetic variation for breeding high biomass and yield in wheat
Amount £1,010,000 (GBP)
Funding ID BB/N021061/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 04/2016 
End 03/2019
 
Description IWYP GWAS
Amount £1,000,000 (GBP)
Funding ID BB/N020871/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 03/2016 
 
Description Rice Research Newton Fund: Exploiting a Cyanobacterial CO2 Concentrating Mechanism to Increase Photosynthesis and Yield in Rice
Amount £341,000 (GBP)
Funding ID BB/N013662/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 01/2016 
 
Description University of Essex 
Organisation University of Essex
Country United Kingdom 
Sector Academic/University 
PI Contribution Led and contributed to number of research grants, joint research discussions, generated new resources and insights.
Collaborator Contribution Led and contributed to number of research grants, joint research discussions, generated new resources and insights
Impact A number of joint research publications and involvement in exchange events
Start Year 2010
 
Description Food, Health and Environmental Security 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact New breeding approaches to increase the yield & quality of crops. Palma de Mallorca, February 20 - 22nd, 2018
Year(s) Of Engagement Activity 2018
 
Description 2nd Agriculture and Climate Change Conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact 2nd Agriculture and Climate Change Conference
Year(s) Of Engagement Activity 2017
 
Description DEFRA University Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact This workshop brought together a group of universities with Defra policy teams / evidence specialists to explore the opportunities available through academic partnerships (including fellowships, studentships and other grant processes) and the benefits of engaging with external academic experts through developing contacts and networks.
Year(s) Of Engagement Activity 2018
 
Description Invited lecture 'Improving Rubisco' at Enhancing Photosynthesis in crop plants: Targets for improvement' at the Royal Society London December 2016 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited lecture 'Improving Rubisco' at Enhancing Photosynthesis in crop plants: Targets for improvement' at the Royal Society London December 2016
Year(s) Of Engagement Activity 2016
 
Description Keynote for Keys Symposia 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Keynote presentation at Keygene Symposia
Year(s) Of Engagement Activity 2017
 
Description Waitrose Agronomy Group 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Plant breeding and genetics for enhanced yield
Year(s) Of Engagement Activity 2017
 
Description World Grain Forum 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact Keynote lecture and breakfast discussion with minister of agriculture at the World Grain forum in Sochi, Russia
Year(s) Of Engagement Activity 2016
 
Description World Life Science Conference in Plant and Environment session, Beijing 2016 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Keynote lecture 'Improving Photosynthesis the engine of Life to Increase Crop Yields' in Plant and Environment session at the World Life Science Conference, Beijing 2016
Year(s) Of Engagement Activity 2016
 
Description • 'Capturing more carbon while using water and nutrients more effectively' Global Plant Council Stress Resilience Symposium Stress Resilience Symposium, Foz do Iguaçu Brazil. October 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited talk 'Capturing more carbon while using water and nutrients more effectively' at the Global Plant Council Stress Resilience Symposium at , Foz do Iguaçu Brazil. October 2015
Year(s) Of Engagement Activity 2015
 
Description • 'Discovery and creation of genetic variation to enhance the yield potential of wheat' Keynote lecture at 9th International Wheat Conference IWC Sydney, Australia September 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited talk 'Discovery and creation of genetic variation to enhance the yield potential of wheat' Keynote lecture at 9th International Wheat Conference IWC Sydney, Australia September 2015
Year(s) Of Engagement Activity 2015
 
Description • 'Plenary Lecture at the 1st International Workshop on Food and Health Security, Lima Peru October 2016. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Plenary talk on 'Discovery and creation of genetic variation to increase crop performance for current and future environments' at the 1st International Workshop on Food and Health Security, Lima Peru October 2016.
Year(s) Of Engagement Activity 2016