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Preliminary studies of the genetics of host-pathogen interactions in strawberry powdery mildew - HH2301SSF

Description
Powdery mildew, caused by Sphaerotheca macularis, is a serious problem in strawberries, particularly of late-season and everbearing types. It is difficult to control with the fungicides available, especially in everbearers because of their long cropping period. Breeding for resistance to mildew has been handicapped by the lack of information on the S.macularis X strawberry pathosystem. A three-year research project is proposed to develop the necessary technological tools and to obtain preliminary knowledge for elucidating the types of resistance to mildew in strawberry and determining the degree of pathogen variation so that unstable and durable resistance can be distinguished.

Techniques will be developed for in vitro production and maintainence of powdery mildew isolates on tissue culture plants or detached leaves, a fundamental requirement for research on host-pathogen interaction. Protocols will be developed to obtain 'monoconidial' (pure) mildew isolates in vitro from selected representive strawberry cultivars. An efficient method will be developed to describe quantitatively host-pathogen interactions either in vitro or in vivo. Preliminary results on the range of host-pathogen interactions (pathogen virulence/host resistance) will be obtained using a number of selecetd cultivar and isolate combinations. Molecular markers will be developed and used to obtain preliminary results on pathogen variabilities and adaptations to host cultivars at molecular levels.

The research work will provide essential knowledge and protocols for future studies of the genetics of the host-pathogen interactions. This is a prerequisite for breeding cultivars with durable resistance to the pathogen. This would help growers produce safe and high quality fruits competitively with minimum fungicide input.

Objective
The overall objective is to develop necessary techniques and to provide initial knowledge for elucidating the genetics of host-pathogen interaction of strawberry powdery mildew. These techniques are a prerequisite for breeding cultivars with durable resistance to powdery mildew. Unlike most other pathogens, isolates of powdery mildew, as a biotroph, cannot be maintained on artifical agar media in vitro. Therefore, much effort is needed to develop protocols for studying host-pathogen interactions for powdery mildew. Molecular markers will be developed and used to obtain preliminary results on pathogen variabilities and adaptations to their hosts.

There are five specific objectives:

1. To develop methods for maintaining mildew isolates and producing mildew conidia in vitro, and for assessing the genetics of host-pathogen interactions in vitro or in vivo efficiently
2. To establish techniques for obtaining 'monoconidial' mildew isolates;
3. To collect and maintain isolates from representative strawberry cultivars;
4. To conduct preliminary studies on host-pathogen interactions;
5. To assess pathogen population variabilities and its adpatations to host cultivars at molecular levels.
The outline of time scale and the overall relationships between the five specific objectives are illustrated in the diagram.


Inter-related objectives 1 – 3 are essential in achieving the overall objective of the proposed work.
Objective 5 will provide indications on the degree of pathogen variabilities and its adpatations to host cultivars at molecular levels and will lay firm foundations for future studies on pathogen variabilities in relation to sexual production, gene flow, durability of host resistance and for development of markers for fungal virulence genes.
Objective 4 is not essential for the overall aim of the proposed work but it would provide valuable inofrmation for conducting future studies on the genetics of host-pathogen interactions on disease development.

If the development of protocols for obtaining, producing and maintaining single spore isolates in vitro takes longer than expected, it may not be possible to achieve objective 4.
Project Documents
• Final Report : Preliminary studies of the genetics of host-pathogen interactions in strawberry powdery mildew   (92k)
Time-Scale and Cost
From: 2001

To: 2004

Cost: £160,316
Contractor / Funded Organisations
Horticulture Research International
Keywords
Biotechnology              
Biotech-non GM              
Disease Control              
Farming              
Fruit              
Horticulture              
Organic Farming              
Strawberries              
Fields of Study
Horticulture
Horticulture