Histochemical Localization of Citral Accumulation in Lemongrass Leaves (Cymbopogon citratus(DC.) Stapf., Poaceae)

Lemongrasses ( Cymbopogon spp., Poaceae) are a group of commercially important C 4 tropical grasses. Their leaves contain up to 1.5% (d.wt) essential oils with a typical lemon-like aroma, consisting mainly of citral (a mixture of the isomeric acyclic monoterpene aldehydes geranial and neral). To specifically locate the sites of citral accumulation in lemongrass we employed Schiff's reagent, which reacts with aldehydes and gives a purple-red coloration with citral. Using this technique, single oil-accumulating cells were detected in the adaxial side of leaf mesophyll, commonly adjacent to non-photosynthetic tissue, and between vascular bundles. Cell walls of these oil cells are lignified. Our results suggest that citral accumulation takes place in individual oil cells within the leaf tissues.