Figure 1. Cell wall integrity signaling components mediate cellular responses upon pathogen attack. Pathogen invasion can be limited by a cell wall structure and composition that is resistant to degradation by cell wall modifying enzymes (CWMEs). Pathogens can be detected by the presence of cell wall fragments (i.e., oligogalacturonides; OGs) generated by CWMEs; these fragments can function as DAMPs and are perceived by Wall Associated Kinases (WAKs), Receptor Like Kinases (RLKs) and Plasma Membrane (PM) sensors. Downstream signaling pathways mediate defense responses (MAPKs, TOR, oxidative burst, hormone mediated pathways of Pathogen Related (PR), CW repair and peroxidases genes, PAL, phytoalexins activation and/or cell wall structural rearrangements such as cell wall repair (PMR4-mediated callose deposition) or cell wall reinforcement (lignin) and de novo synthesis of defensive compounds such as defense proteins including CWME inhibitors (PGIPs, XIP, XEGIP, PMEI).