Abstract text: Pathogens breach plant defenses by targeting and degrading the extracellular matrix that surrounds plant cells, generating cell wall–derived damage-associated molecular patterns (DAMPs). A central unresolved question is how these DAMPs are perceived and molecularly integrated to activate immune signaling. Here, we address this question by determining high-resolution structures of the multidomain immune receptor IGP1 in both its apo state and in complex with the cellulose-derived DAMP cellotriose. Our structural and biochemical analyses reveal that constitutive interactions between the Leucine-Rich Repeat (LRR) and malectin domains preconfigure IGP1 into a ligand-competent architecture, priming the receptor for rapid ligand recognition. We further uncover a highly specific glycan-binding pocket within the LRR domain that discriminates subtle structural variations among oligosaccharides. By directly sensing cello-oligomers generated during pathogen-mediated cell wall degradation, IGP1 functions as a dedicated cell wall sentinel, mechanistically linking extracellular damage to immune activation. These findings provide a structural  and molecular framework for understanding how plants detect cell wall integrity perturbations and mount timely, robust defense responses.