Secretome Analysis of - Interaction Unveils New Roles for the Plant Glutamate:Glyoxylate Aminotransferase GGAT1 in Plant Growth Induced by the Fungus and Resistance against .

The establishment of plant-fungus mutualistic interaction requires bidirectional molecular crosstalk. Therefore, the analysis of the interacting organisms secretomes would help to understand how such relationships are established. Here, a gel-free shotgun proteomics approach was used to identify the secreted proteins of the plant and the mutualistic fungus during their interaction. A total of 126 proteins of and 1027 of were identified. Among them, 118 and 780 were differentially modulated, respectively. Bioinformatic analysis unveiled that both organisms' secretomes were enriched with enzymes. In , glycosidases, aspartic endopeptidases, and dehydrogenases increased in response to . Additionally, amidases, protein-serine/threonine kinases, and hydro-lyases showed decreased levels. Furthermore, peroxidases, cysteine endopeptidases, and enzymes related to the catabolism of secondary metabolites increased in the plant secretome. In contrast, pathogenesis-related proteins and protease inhibitors decreased in response to the fungus. Notably, the glutamate:glyoxylate aminotransferase GGAT1 was secreted by during its interaction with . Our study showed that GGAT1 is partially required for plant growth stimulation and on the induction of the plant systemic resistance by . Additionally, GGAT1 seems to participate in the negative regulation of the plant systemic resistance against through a mechanism involving HO production.