Composition changes in the cuticular surface lipids of the helophytes Phragmites australis and Juncus effusus as result of pollutant exposure

Aim of the study Helophytes like rush and reed are increasingly used for phytoremediation of contaminated water. This study characterises the response of rush and reed plants to chemical stressors such as chlorobenzene, benzene and methyl-tert-butyl ether. The extractable wax layer of the cuticle was chosen for detailed investigations due to its multiple, particularly, protective functions for plants and its easy availability for analysis. Methods The chemical composition of the cuticle wax layer of reed and rush was studied in dependence on chemical stress caused by contaminated water under wetland cultivation conditions. The lipid layer of leaves was extracted, derivatised and investigated by GC-MS using retention time locking and a plant-specific data base. Results In case of rush, a remarkable increase of the total lipid layer and a prolongation of the mean chain length resulted as response on a chlorobenzene exposure. The significant difference in the substance profiles of exposed plants and controls could be confirmed by multivariate data analysis. The lipid layer of reed was not changed significantly when the plants were exposed to water polluted with benzene and methyl-tert-butyl ether. However, scanning electron microscopic images of the exposed reed leaves indicated alterations in the crystal structure of their wax surface. Conclusion The composition and morphology of cuticular waxes indicated the plants' response to chemical stress very sensitively thus, changes in the wax layer could be used as an indication for growing in a contaminated area.