Award details

Engineering wheat for take-all resistance

Reference	BB/K006746/1
Principal Investigator / Supervisor	Dr Emma Wallington
Co-Investigators / Co-Supervisors	Professor Andy Greenland
Institution	National Inst of Agricultural Botany
Department	Centre for Research
Funding type	Research
Value (£)	686,328
Status	Completed
Type	Research Grant
Start date	05/03/2013
End date	14/08/2019
Duration	77 months

Abstract

Take-all disease has a substantial impact on wheat yield throughout the cereal-growing areas of the world and is a major threat to food security. The cost of this fungal disease to wheat production in the UK is estimated at £85-340m per annum. Take-all is a ubiquitous and chronic problem that that imposes serious limitations on wheat production as roughly half of UK wheat crops are affected. Introduction of genes through conventional breeding strategies relies on the identification of resistances through screening, and subsequent crossing into elite varieties, and is the approach taken in the wheat pre-breeding LoLa (BB/J004596/1). Our proposal takes a complementary approach that involves the direct introduction of cloned genes for take-all resistance into wheat through genetic modification (GM) which has the potential for more rapid delivery of useful genes into elite wheat varieties. We have assembled a customised toolkit for triterpene metabolic engineering in plants consisting of characterised genes and enzymes from oat and other plant species. Our aim is to engineer single and multiple steps for triterpene synthesis into hexaploid wheat and evaluate the consequences of this for triterpene production, plant performance and take-all resistance. The development of methods for high-efficiency transformation of wheat with multiple genes within this proposal will lay the foundation for introduction of other valuable multi-gene traits/processes (e.g. nitrogen fixation, C4 photosynthesis, polygenic pest/pathogen resistance, seed micronutrient content) into wheat in the future. The key deliverables and outcomes of this research programme will be: 1. Evaluation of a transgenic approach to engineer wheat for the synthesis of protective triterpenes; 2. Establish a multi-gene wheat transformation platform; 3. Provide industry with a potential solution to take-all disease; 4. Training of project scientists in cross-disciplinary and applied crop research

Summary

Wheat is one of the most important food items for humans and animals around the world. In the UK, wheat is sown on over 1.8 million hectares with a production value of ~£1.7 billion. Although significant increases in yield have been achieved during the last half century, the current and future demands for wheat and other cereals will require accelerated increases in productivity. This emerges as a grand challenge for society as we seek to produce enough food for a growing global population (with changing dietary preferences) in a sustainable manner. Take-all disease, caused by the soil fungus Gaeumannomyces graminis var. tritici (Ggt), is the most damaging root disease of wheat worldwide. The introduction of genes for take-all resistance into cultivated wheat has been identified as a top priority by the UK plant breeding industry and by HGCA on behalf of arable farmers (see accompanying letters from a consortium of UK plant breeders and from HGCA). At least half of UK wheat crops are affected by the disease, with average yield losses of 5-20% and complete failure under severe take-all conditions. Conservative estimates of the cost of take-all associated yield losses in the UK range from £85 m to £340 m per annum. Disease severity increases with successive wheat cropping, therefore growth of second and third wheat crops in the same fields can become commercially unviable. This problem will be exacerbated as the need for food production increases and cropping systems becomes even more intensive. Thus take-all disease represents a major threat to UK and world food security and there is an urgent need for simple, economic and sustainable strategies for disease control. Current control methods rely on crop rotation, biological control and fungicides, none of which are effective in preventing the yield losses indicated above. The most effective way to achieve simple, economic and sustainable control of take-all disease is through genetic resistance. Resistance to take-all would represent a step-change in wheat productivity, ensuring food security and enhanced industry competitiveness. It would also expand the ability to grow wheat in successive cropping seasons and increase its geographic distribution, and reduce chemical and fertiliser inputs. Unfortunately, there is no known major varietal resistance to take-all in cultivated wheat lines and hence the disease has so far proved to be intractable to breeders. In contrast, oats have extreme resistance to take-all and produce an antimicrobial triterpene glycoside (avenacin A-1) that provides protection against the disease. Wheat and other cereals do not make avenacin A-1 or appear to make other triterpene glycosides. We have cloned and characterised most of the genes for avenacin synthesis from oat. These genes are currently the only characterized source of genetic resistance to take-all from any cereal or grass species. Oat is too far removed from wheat to allow introduction of the genes for avenacin synthesis through conventional crossing or alien introgression, making genetic transformation the only viable option for introduction of these genes into wheat. The aim of this proposal is to engineer wheat to produce a suite of protective triterpenes that confer resistance to take-all disease. To do this we have assembled a customised toolkit for triterpene metabolic engineering using characterised genes and enzymes from oat and from dicot plant species.

Impact Summary

The most important impact of this research will be the evaluation of a metabolic engineering strategy for control of take-all disease of wheat. This has the potential to provide the plant breeding industry with a strategy for disease control that will complement longer-term strategies currently being initiated within the wheat pre-breeding LoLa. There are many environmental and economic costs associated with take-all that have a detrimental effect on the overall competitiveness and sustainability of the UK arable industry. Introduction of take-all resistance into cultivated wheat will have a profound impact on reducing these negative externalities across the production sector. We expect there to be a number of different beneficiaries of the proposed work. These will include the private sector in the form of wheat farmers and breeding companies, the UK environment, policy makers, and the wider public in general. Many of the expected benefits will be shared between groups and we have outlined some of these below: - Increased yields: At least half of UK wheat crops are affected by take-all, with average yield losses between 5-20% and complete failure of the crop under severe take-all conditions. The average UK wheat production value is ~£1.7 b. Therefore the minimum cost of take-all to the UK arable industry is between £85m - 340m per annum. The availability of take-all resistant wheat would significantly reduce this loss and provide increased flexibility to farmers. - Testing the potential of GM approaches: This work will test the potential of a GM approach to take-all control. The multi-gene wheat transformation platform established within this programme will provide cutting-edge enabling technology for academic researchers and industry for future wheat improvement for disease resistance and other important traits/processes (e.g. nitrogen fixation). - More efficient use of nitrogen fertilization: Take-all disease leads to reduced uptake of nitrogen by the roots. Not only is this inefficient and costly but the remaining nitrogen leaches into farmland water courses, so contributing to pollution and eutrophication. Improving resistance to take-all would therefore have both direct financial benefits (reduced nitrogen requirements of second and third wheat crops) and indirect consequences of improving nitrate utilisation, reducing wastage and increasing overall competitiveness of UK wheat growers. - More efficient land use: Improved take-all resistance will result in increased yields in second and third wheat situations, enabling more wheat to be produced from the same amount of land. This will help in the sustainable intensification of UK agriculture, increasing the efficiency of land use and providing farmers with enhanced flexibility in their farm management practices. - Training the next generation of crop scientists: This proposal brings together a unique combination of disciplines that will provide an exciting training ground for the project scientists involved. The resulting innovation and training will provide the next generation of skilled crop scientist, with benefits beyond the plant breeding industry, and boosting the UK economy.

Committee	Research Committee B (Plants, microbes, food & sustainability)
Research Topics	Crop Science, Microbiology, Plant Science, Synthetic Biology
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

Associated awards:

BB/K005952/1 Engineering wheat for take-all resistance

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