The root system of transgenic tobacco plants expressing the enhanced green fluorescent protein (EGFP) under the control of the 35S cauliflower mosaic virus (CaMV) promoter, were colonized with the endomycorrhizal fungus Glomus intraradices. Translocation of EGFP protein from the root to the fungus was registered by light and confocal microscopy. Immunolocalization also showed the presence of EGFP in the mycelium of Glomus intraradices. Carboxyfluorescein feeding experiments on wild type mycorrhized plants evidenced the transport of fluorescein, a symplasmic tracer, from the plant to the fungus. Our results suggest that endomycorrhiza possess the capacity to exchange functional biological macromolecules as evidenced by the transport EGFP from the plant to the fungal symbiont.