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Fellowship in Crop Environment Interactions with Pathogenic Fungi - AR0511

The Fellowship in Crop Environment Interactions with Pathogenic Fungi will develop and foster sustainable approaches to the management of pathogenic fungi. Heritable variation in disease escape, resistance and tolerance should be utilised for crop genetic improvement and accounted for in management decisions, in order to minimise pesticide use. Such sustainable approaches are required because changes in the wheat crop over the last two decades have led to loss of resistance genes due to pathogen adaptation, disease intolerance and greater dependence on fungicides. The objective fits within the draft Defra Science and Innovation Strategy aims: to manage pests and diseases within farming systems that are more resource-efficient, less polluting and which ensure the conservation and sustainable use of genetic resources.

The main objectives are to:1.Identify mechanisms of interactions between pathogenic fungi, crop canopy and environment which determine disease escape and tolerance. 2.Foster sustainable approaches to the management of pathogenic fungi, in order to minimise pesticide use and conserve genetic resources.

Objective 1
Disease tolerance is defined here as the heritable capacity of a crop to maintain yield despite the presence of disease. In Parker et al. [1], we define absolute units for tolerance and present evidence for significant tolerance variation between commercial wheat genotypes. Tolerance has not been selected for in plant breeding programmes. In fact, we found an association between high attainable yield and greater loss per unit disease (intolerance), which explains a proportion of the trend towards greater disease-induced losses – and hence greater fungicide requirement – in high yielding, modern wheats. Reducing fungicide requirement by selecting for tolerance would provide a sustainable disease management solution, for two reasons. Firstly, tolerance does not result in selective pressure on pathogen populations, so efficacy will be maintained and plant genetic resources will not be eroded by pathogen adaptation. Secondly, certain tolerance mechanisms are likely to be effective against a range of pathogen species, so changes in the spectrum of important pathogens that occur over time will not result in loss of effect. However, reversing the trend towards intolerance is complicated by the need to identify tolerance mechanisms and traits which are compatible with efficient crop resource capture. Techniques to identify such traits are described in sections 9 and 11(a).

Disease escape is defined here as a host mechanism that reduces arrival of pathogen spores on the upper canopy that is crucial to resource capture. We have demonstrated, using isogenic lines varying for dwarfing genes, but with a constant background of resistance, that increasing the separaton distance between infectious lesions on lower leaves and newly emerged upper culm leaves, delays epidemic development to an equivalent extent to a full dose fungicide treatment. This beneficial escape effect appears to be generic in its effect against splash-dispersed pathogens (it has now been demonstrated against Septoria tritici and Stagonospora nodorum on wheat and Rhynchosporium secalis in barley) and stable across environments. European breeding programmes are inadvertently selecting traits that reduce the expression of escape. However, studies of commercial varieties and lines from a doubled-haploid mapping population, suggest combinations of traits which contribute to escape, without requiring excessive crop height. Techniques to identify mechanisms and traits determining escape are described in sections 9 and 11(a).

The results of the work will be used to benefit:
Defra: by furthering its policy objectives and in providing evidence to support research and policy decisions. Consumers and the environment: through reduced pesticide use and sustainable use of genetic resources. The arable industry: via LINK and levy initiatives to reduce fungicide dependence.

New information resulting from the project will be made widely available through publication and uptake will be actively encouraged. Improvements to prediction of disease and disease-yield loss relationships arising from understanding of crop/pathogen/environment interactions will be used to underpin disease risk initiatives - for example via the DESSAC dissemination project (AR0915), and the live monitoring reported to crop managers through the Defra project ‘Crop health status and protection practice in major UK combinable crops’ (AR0503). The work will be undertaken in co-ordination with the Defra Wheat Genetic Improvement Network. Work will be undertaken on mapping populations that are being used for other purposes within the Network, where trait variation is complementary and there would be synergy (for example, in sharing phenotyping or mapping information). Sources of novel variation in germplasm resulting from the work will be made freely available for research.
The main long term benefits will accrue from understanding mechanisms of management of pathogenic fungi that are generic in effect and not subject to loss through pathogen adaptation and selection.

Objective 2
Achievement of the second objective will involve:
· Providing information and advice of policy relevance to Defra, based on research evidence.
· Advocating sustainable approaches to the management of pathogenic fungi to industry and stakeholders.
· Convening and Chairing a Steering Group across inter-linked research projects. The group to comprise Defra and industry representatives, research leaders and independent peer reviewers.
· Facillitating flow of new mechanistic understanding and data between initiatives, in the following Defra research areas:
- Genomics of crop environment interactions - working closely with the Defra Wheat Genetic Improvement Network.
- Crop management decision support - providing support to the DESSAC initiative, to enable best practice.
- Modelling of crop/pathogen interactions - in collaboration with Defra funded research projects.
- Crop Health Status and Crop Protection Practice – underpining provision of live intelligence.
- Crop design for sustainability - in relation to work in the Crop Technology for Resource Productivity Programme.

The flow of outcomes from the Fellowship, and inter-relationships with other initiatives, are summarised in the appended flowchart.
Time-Scale and Cost
From: 2003

To: 2007

Cost: £813,484
Contractor / Funded Organisations
Arable Farming              
Crop Diseases              
Sustainable Farming and Food              
Sustainable Production              
Fields of Study
Arable Crops