Systematic and functional aspects of symbiotic fungi

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The central part of this proposal has two principal components: the development of a promising novel and robust identification tool for arbuscular mycorrhizal (AM) fungi, and the continued exploration of the functional aspects associated with the establishment of the AM symbiosis. A third component aims to provide a greater insight into the factors responsible for initiating ectomycorrhizal (ECM) fungal fruitbody formation. For the AM symbiosis, a major challenge that hampers biodiversity studies is the correct identification of the mycobionts. The proposed project will couple classical identification, based on spore morphology, with the design of species-specific molecular probes. This approach will allow identification of AM fungi and the determination of the genetic delimitation of a given species. A second project will investigate cytoplasm streaming, and the movement and activity of organelles in AM fungal germ tubes exhibiting either the fine branching or runner hyphae growth pattern. The phenotypic expression of the extraradical mycelium of genetically distinct clusters of Glomus spp. will also be characterized using the Fractal Dimension Calculator program. For the EMC symbiosis, most fruitbodies develop at the end of summer, after bud set of the host tree. This suggests that plant-derived photoperiod-regulated signals play a key role in triggering the formation of ECM fungal primordia. An in vitro system will be used to test this theory, and to test the effect of diverse treatments on fruitbody formation. The outcome of the research on AM fungi will be the accurate identification of species and an improved understanding of their diversity, biology and ecology. Finally, it is envisaged that investigations into the role of plant-derived signal as potential initiators of ECM fruiting bodies, will have applications in the cultivation and commercial production of edible ECM fungi.