Signalling pathways that regulate the expression of plant genes are poorly understood. Recent evidence indicates that octadecanoid-derived signals may be parts of signalling pathways in plants in which C(18) fatty acids, liberated from membranes in response to environmental or developmental cues, are converted to intracellular signalling molecules such as jasmoric acid and traumatin. These events are analogous to prostaglandin and leukotriene synthesis in animals.