Extracellular salicylic acid activates immune signaling through cell-surface receptors
Li, Q.; Zhou, M.; Sharma, C.; Ramdhan, P. A.; Louwerse, C. R.; Merritt, B. A.; Yu, F.; Zhang, Y.; Li, C.; WANG, X.; Mou, Z.
Plant Signaling
Aspirin's plant cousin — salicylic acid — turns out to work like a doorbell on the outside of plant cells, and understanding that mechanism could lead to crops and garden plants that mount faster, stronger defenses against disease without chemical sprays.
Plants make a natural chemical called salicylic acid when they're under attack by disease. Scientists always thought this chemical only worked inside plant cells, but this study shows plants also have special sensor proteins on the outside of their cells that can detect it floating around in the spaces between cells. When those outside sensors pick up the signal, they kick off a whole chain of defense responses — like an alarm system that works from the outside in, not just from within.
Key Findings
Two plasma membrane receptor proteins (LecRK-I.8 and LecRK-VI.2) in Arabidopsis bind extracellular salicylic acid with micromolar affinity, suggesting a direct cell-surface perception mechanism
Mutagenesis of a computationally predicted binding pocket in LecRK-VI.2 abolished both salicylic acid binding and immune function, providing causal evidence for receptor-mediated signaling
Plants lacking these LecRK receptors showed impaired salicylic acid-induced resistance, altered gene expression programs, and reduced phosphoproteomic responses, confirming their role in downstream immune activation
chevron_right Technical Summary
Scientists discovered that plants don't just sense the immune hormone salicylic acid inside their cells — they can also detect it outside cells using surface receptors, triggering defenses against pathogens through a newly identified signaling pathway.
Abstract Preview
Salicylic acid (SA) is a central immune hormone that accumulates in both intracellular and extracellular compartments during pathogen infection. While intracellular SA signaling is well established...
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