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Our hypothesis is that changes in plant metabolites due to different experimental conditons (elevated or ambient O3 and CO2) are recognized in the root surrounding soil. In our project, the so called "mycorrhizosphere" is the target compartiment. It comprises ectomycorrhizae, surrounding soil, soil microorganisms and mycorrhiza associated microorganisms. The mycorrhizosphere is characterised by high microbial activity and nutrient turnover since root exudates stimulate the organisms in the surrounding environment by providing "ready to use" carbon and nitrogen sources. Ectomycorrhizal roots themselves may also influence their direct surroundings due to specials requirements and capabilities of the respective fungal partner such as nutrient uptake, pathogen defense or by providing special conditions for other microorganisms which could e.g. contribute to a beneficial microbial population.
In phase 1, we focused mainly on microbial populations in the mycorrhizosphere and forest soils and developed specific detection and identification methods.
In phase 2, population analyses have been continued and supplemented by functional analyses under a range of experimental conditions.
In phase 3, the specific influence of different mycorrhizal partners on functions such as C- and N-allocation and enzymatic activities is studied. A special focus is the characterisation of enzymes involved in nutrient turnover. |
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