The molecular dialogue between the Arbuscular Mycorrhizal Fungi (AMF) and their host regulates symbiosis establishment. It involves strigolactone, a phythormone released by host roots, and Mycfactors released by fungal spores. Other phytohormones are involved in the development of this symbiosis as well, but they are always examined from the plant point of view. Recently, AMF cytokinins and ethylene receptors were identified in silico. It is therefore tempting to speculate that AMF perceive cytokinines or ethylene produced by plants as well. Furthermore, many ectomycorrhizal fungi are reported to produce phytohormones, but there is no strong evidence for AMF. We thus wonder whether AMF may perceive phytohormones imported from root-fungus exchange, or metabolized by AMF themselves. We therefore developed biochemical strategies to detect phytohormones in AMF. A global extraction and enrichment protocol for soluble phytohormones was adapted to different matrixes, like Germination Spores Exudates (GSE) and double compartment culture. In parallel, their detection and identification by liquid chromatography coupled to mass spectrometry was optimized. Ethylene production by fungal spore was investigated by gas chromatography, to decipher its biosynthesis pathways. We have been able to detect for the first time several phytohormones released by spores and extra-radical mycelium. Their metabolic origins, as well as their effect on AMF development still remain unknown and will be further investigated through this project.