Terpenoids and Plant Communication

Terpenoids are compounds containing an integer number of 5C units, the «syllables».There is an astonishing array of structures, the «words», resulting from the sequential combination of these basic five-carbon units in the familiar categories of C10 (mono-), C15 (sesqui-), C20 (di-), C30 (tri-) C40 (tetra-) and C>40 (poly-) terpenoids.Terpenoids are induced and emitted in response to internal (genetic and biochemical) and external (ecological) factors, both abiotic and biotic.They are emitted in quantitatively and qualitatively diverse blends, the «messages», that arrive to the environment either through volatilization (mono-and sesquiterpenes), leaching or decomposition of plant debris.Their information or effect is received and responded by other parts of the plant, other plants, animals and microorganisms.Part of such terpenoid «words» are common to all plants.For example, carotenoids, chlorophylls or hormones such as cytokinins, gibberellins, or abscicic acid, are terpenoid derivatives.But there are also «dialects» of the terpenoid «language» that are qualitatively or quantitatively characteristic of each family and each species, or even each cultivar and each organ of the plant.They even seem to be kept in «memory».Some plants might remember previous exposures and produce terpenes (and compounds of other chemical languages such as phenolics or alkaloids) when they are needed.Thus, plants also have languages, and that of terpenoids is one of them.