Discovering genus-specific mycoparasites against plant pathogens

在过去的十年里，由于化学农药的环境危害效应，植物病害的生物防治越来越受到重视。由于几种微生物利用各种机制有效地保护植物免受病原体的侵袭，真菌重寄生虫或真菌寄生被视为控制赤霉菌/镰刀菌等种子和根腐病病原菌暴发的生态解决方案。但到目前为止，仅有少数基于木霉菌和粘菌的重寄生虫产品上市。尽管几种生物可以在受控条件下控制病原菌种群，最近的研究表明，在现场使用这些真菌寄生虫存在基本问题。例如，它们是高度依赖于环境条件和兼性坏死菌的多面手，这些坏死菌往往对非目标微生物造成有害影响。因此，本研究的目标是寻找更有效的生物替代品，其基础是生物营养型真菌比一般坏死菌更容易预测。尽管它们是宿主特有的，因此仅限于包括致病G/F在内的特定真菌分类群。它们似乎主要依赖于病原体-宿主种群的分散，因此将是主要的生防候选者。目前，人们对它们的生物学知之甚少。需要阐明的多样性和寄主相互作用。其具体目标是：1)通过现场调查构建与植物致病G/F种群相关的关键属特有重寄生生物的生物图谱；2)了解生物营养性重寄生生物的进化和特化。将使用形态和分子方法对G/F种的这些真菌进行检测，依赖培养和不依赖培养的分析，以评估它们对疾病发展的影响。这一结果将为一组在可持续农业和林业生产生态系统中具有高潜力生防应用的生物提供新的知识体系。对这些生物营养过度寄生虫的了解将导致有效和安全地控制土壤传播的植物病原体和种子传播的真菌毒素产生G/F联合体。总的来说，该项目为加拿大对植物病原体的生物防治提供了一个新的维度。

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.