Establishing a Symbiotic Interface between Cultured Ectomycorrhizal Fungi and Plants to Follow Fungal Phosphate Metabolism.

In ectomycorrhizal plants, the fungal cells colonize the roots of their host plant to create new organs called ectomycorrhizae. In these new organs, the fungal cells colonize the walls of the cortical cells, bathing in the same apoplasm as the plant cells in a space named the 'Hartig net', where exchanges between the two partners take place. Finally, the efficiency of ectomycorrhizal fungi to improve the phosphorus nutrition of their host plants will depend on the regulation of phosphate transfer from the fungal cells to plant cells in the Hartig net through as yet unknown mechanisms. In order to investigate these mechanisms, we developed an experimental device mimicking the common apoplasm of the ectomycorrhizae (the Hartig net) to study the phosphorus metabolism in the ectomycorrhizal fungus when the fungal cells are associated or not with the plant cells of the host plant . This device can be used to monitor Phosphate efflux from the fungus previously incubated with P-orthophosphate.