SURFACE LIPID-COMPOSITION OF C-3 AND C-4 PLANTS

The characteristic surface lipid compositions of several C3 and C4 plants are discussed. C4 plants produce surface lipids (epicuticular waxes) made up of the ubiquitous classes of aliphatic compounds: free fatty acids, aldehydes, primary alcohols, alkanes and aliphatic linear esters. C3 plants synthesize surface lipids comprising the ubiquitous classes and either of the two following groups of compound: (i) beta-diketones, hydroxy beta-diketones, alkan-2-ol esters; (ii) ketones and secondary alcohols with the functional group in the middle of the hydrocarbon chain. These features are suggested to represent physiological characteristics of the plant and to be related to ecological adaptations. Wax class compositions might also be an ancillary method for defining the C3 or C4 mechanism of CO2 assimilation in cases where uncertainty exists.