Updated publication reference for PubMed record(s): 28785276. A delicate balance is required for plants to distinguish mutualist from parasitic organisms. Mitogen-activated protein kinase (MAPK) cascade is one of the signaling modules that mediate transduction of extracellular microbial signals into appropriate cellular response. Here we employ a transgenic system that simulates activation of two pathogen/stress-inducible MAPKs to study release of metabolites and proteins into root exudates. The premise is based on our previous proteomics study that suggests upregulation of secretory processes in this transgenic system. An advantage of this experimental set-up is the direct focus on MAPK-regulated processes without confounding complications of other signaling pathways activated by exposure to microbes or microbial molecules. Using non-targeted metabolomics and proteomics studies, we show that MAPK activation can indeed drive the exudation of dipeptides, defense-related metabolites and proteins in roots. However, the relative levels of other substances were decreased. This points to a bidirectional control of metabolite and protein release into the apoplast. The putative roles for some of the identified exudated metabolites and proteins are discussed with respect to possible antimicrobial/defense or allelopathic properties. Overall, our findings demonstrate that MAPKs regulate the composition of apoplastic root metabolites and proteins, presumably to influence the plant-microbe interactions in the rhizosphere.