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.