Discovering genus-specific mycoparasites against plant pathogens

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Over the last decade, biological control of plant diseases has received increasing attention due the environmental hazard effects of chemical pesticides.  Several microorganisms use various mechanisms to effectively protect plants against pathogens, and fungal hyperparasites or mycoparasites are seen as an ecological solution to control outbreaks of seed and root-rot pathogens such as Giberella/Fusarium (G/F).  Only a handful of hyperparasite products based on Trichoderma and Gliocladium have been marketed so far.  While several organisms may control pathogen populations under controlled conditions, recent studies showed fundamental problems in using these mycoparasites in situ.  They are generalists that strongly depend on environmental conditions and facultative necrotrophs that often detrimentally affect non-target microbes.  The goal of this research is therefore to find more efficient biological alternatives, based on the hypothesis that biotrophic mycoparasites would be more predictable than general necrotrophs.  They are host specific and thus restricted to particular fungal taxa including pathogenic G/F.  They seem to depend mainly on the dispersion of pathogen-host population and thus would be prime biocontrol candidates.  Currently, little is known about their biology, diversity and host-interaction which need to be clarified.  Specific goals are: 1) to construct the bioprofile of key genus-specific hyperparasitic organisms associated with plant pathogenic G/F populations through an in situ survey, and 2) to understand biotrophic hyperparasites evolution and specialisation.  These mycoparasites of G/F species will be examined using morphological and molecular approaches, culture dependent and culture-independent assays to assess their impact on disease development.  The results will provide a new body of knowledge on a group of organisms with high potential for biocontrol applications in sustainable agricultural and forest production ecosystems.  Knowledge on these biotrophic hyperparasites will lead to an effective and safe control of soilborne plant pathogenic and seedborne mycotoxin producing G/F consortia.  Overall, this project offers a new dimension for Canadian biocontrol against plant pathogens.