Salicylic acid (SA) is a mandatory plant metabolite in the deployment of systemic acquired resistance (SAR). a broad-spectrum systemic immune response induced by local inoculation with avirulent pathogens. The NPR1 transcription co-activator is the central node positively regulating SAR. SA was the last of the major hormones to be without a known receptor. https://www.tourettebrewing.com/