Coronatine (COR) is a toxin produced by the bacterium Pseudomonas syringae. It is involved in causing stomata to re-open after they close in response to pathogen-associated molecular patterns, as well as interfering with the responses mediated by salicylic acid after the infection has begun. It consists of coronafacic acid (CFA), which is an analog of methyl jasmonic acid (MeJA), and coronamic acid (CMA), joined by an amide bond between the acid group of CFA and the amino group of CMA.[1]