and olive oil. Meat, poultry, fish, eggs, dairy products, sugar, breads and cereals have low salicylate content. Some people with sensitivity to dietary salicylates may have symptoms of allergic reaction, such as bronchial asthma, rhinitis, gastrointestinal disorders, or diarrhea, so may need to adopt a low-salicylate diet. Plant hormone Salicylic acid is a phenolic phytohormone, and is found in plants with roles in plant growth and development, photosynthesis, transpiration, and ion uptake and transport. Salicylic acid is involved in endogenous signaling, mediating plant defense against pathogens. It plays a role in the resistance to pathogens (i.e. systemic acquired resistance) by inducing the production of pathogenesis-related proteins and other defensive metabolites. SA's defense signaling role is most clearly demonstrated by experiments which do away with it: Delaney et al. 1994, Gaffney et al. 1993, Lawton et al. 1995, and Vernooij et al. 1994 each use Nicotiana tabacum or Arabidopsis expressing nahG, for salicylate hydroxylase. Pathogen inoculation did not produce the customarily high SA levels, SAR was not produced, and no PR genes were expressed in systemic leaves. Indeed, the subjects were more susceptible to virulent and even normally avirulent pathogens. Exogenously, salicylic acid can aid plant development via enhanced seed germination, bud flowering, and fruit ripening, though too high of a concentration of salicylic acid can negatively regulate these developmental processes. The volatile methyl ester of salicylic acid, methyl salicylate, can also diffuse through the air, facilitating plant-plant communication. Methyl salicylate is taken up by the stomata of the nearby plant, where it can induce an immune response after being converted back to salicylic acid. Signal transduction A number of proteins have been identified that interact with SA in plants, especially salicylic acid binding proteins (SABPs) and the NPR genes (Nonexpressor of pathogenesis related genes), which are putative receptors. See also Salsalate Trolamine salicylate References Further reading External links Salicylic acid MS Spectrum Safety MSDS data International Chemical Safety Cards | CDC/NIOSH "On the syntheses of salicylic acid": English Translation of Hermann Kolbe's seminal 1860 German article "Ueber Synthese der Salicylsäure" in Annalen der Chemie und Pharmacie'' at MJLPHD Anti-acne preparations Antiseptics Chelating agents Monohydroxybenzoic acids Nonsteroidal anti-inflammatory drugs Plant hormones World Health Organization essential medicines