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Population genetics of vegetable downy mildew fungi in relation to breeding resistance. - HH0916SFV

The objective of this project is to:
• Assess the variability in UK plant pathogens on crops and a weedy wild relative for virulence and fungicide insensitivity.
• Determine the relationship between the pathogen isolates from the two types of host.
• Assess whether current known sources of resistances in the crop are effective against the UK pathogen population.
• Determine whether species level (non-host) resistance exists in weedy relatives of crops.

The project will use as a model sytem the two obligate pathogens Peronospora parasitica and Albugo candida which cause downy mildew and white blister respectively, of vegetable brassicas and two weedy wild relatives shepherds purse and thale cress. Information generated by the project will inform strategies for the deployment of resistance genes aimed at obtaining durable disease control via host resistance which is an objective of MAFF ROAME A HH09 - breeding annual crops. Material products from the project (defined differential host lines and a collection of pathogen isolates) will be of value for future studies of the response of pathogens to the deployment of resistance genes and for breeders in identifying new resistances. Information on the variability of pathogen poulations (both for virulence and fungicide insensitivity) and the role of weed hosts as sources ofinoculum will inform models for disease forecasting which enable a more precise use of fungicides.
1. To produce a set of host differentials for use in studying pathogen variability.
2. To establish a collection of UK isolates of P. paraitica and A. candida.
3. To characterise the isolate collections for virulence phenotype.
4. To determine the allelic relationship between different resistance factors.
5. To classify pathogen isolates into subspecifc groups by comparing variation in ITS sequences.
Project Documents
• Final Report : final report   (3895k)
Time-Scale and Cost
From: 2000

To: 2002

Cost: £217,985
Contractor / Funded Organisations
Horticulture Research International
Organic Farming              
Fields of Study