The establishment of plant-mutualistic fungi interaction requires a bidirectional molecular crosstalk. The study of their secretomes help to understand a beneficial relationship. Here, a gel-free shotgun proteomic approach was used to identify secreted proteins from semi hydroponic culture systems with Arabidopsis (Arabidopsis thaliana) and T. atroviride alone or in co-culture over a time course (24, 48 and 96h). A total of 126 proteins of Arabidopsis and 1027 proteins of T. atroviride were identified, 118 and 780 of which were differentially modulated in response to their interaction, respectively. Bioinformatic analysis revealed that the secretomes of both organisms were enriched in proteins with a predicted enzymatic function. Among these, increased abundance of putative glycosidases, aspartic endopeptidases and dehydrogenases, together with decreased abundance of amidases, protein-serine/threonine kinases and hydro-lyases was observed in T. atroviride secretome in response to the plant, whereas increased abundances of peroxidases, cysteine endopeptidases and enzymes related to catabolism of secondary metabolites, together with decreased abundance of pathogenesis-related proteins and protease inhibitors was observed in the plant secretome in response to the fungus. Finally, the plant alanine-glyoxylate transaminase GGAT1, increased in abundance, is required for the systemic disease resistance against the phytopathogen Botrytis cinerea but not for plant growth stimulation by T. atroviride