Epicuticular wax on cherry laurel (Prunus laurocerasus) leaves does not constitute the cuticular transpiration barrier.
Epicuticular wax of cherry laurel does not contribute to the formation of the cuticular transpiration barrier, which must be established by intracuticular wax. Barrier properties of cuticles are established by cuticular wax deposited on the outer surface of the cuticle (epicuticular wax) and in the cutin polymer (intracuticular wax). It is still an open question to what extent epi- and/or intracuticular waxes contribute to the formation of the transpiration barrier. Epicuticular wax was mechanically removed from the surfaces of isolated cuticles and intact leaf disks of cherry laurel (Prunus laurocerasus L.) by stripping with different polymers (collodion, cellulose acetate and gum arabic). Scanning electron microscopy showed that two consecutive treatments with all three polymers were sufficient to completely remove epicuticular wax since wax platelets disappeared and cuticle surfaces appeared smooth. Waxes in consecutive polymer strips and wax remaining in the cuticle after treatment with the polymers were determined by gas chromatography. This confirmed that two treatments of the polymers were sufficient for selectively removing epicuticular wax. Water permeability of isolated cuticles and cuticles covering intact leaf disks was measured using (3)H-labelled water before and after selectively removing epicuticular wax. Cellulose acetate and its solvent acetone led to a significant increase of cuticular permeability, indicating that the organic solvent acetone affected the cuticular transpiration barrier. However, permeability did not change after two subsequent treatments with collodion and gum arabic or after treatment with the corresponding solvents (diethyl ether:ethanol or water). Thus, in the case of P. laurocerasus the epicuticular wax does not significantly contribute to the formation of the cuticular transpiration barrier, which evidently must be established by the intracuticular wax.
Department of Ecophysiology, Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, 53115, Bonn, Germany.
Viktoria
V
Zeisler
Department of Ecophysiology, Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, 53115, Bonn, Germany. lukas.schreiber@uni-bonn.de.
Lukas
L
Schreiber
D001692:Biological Transport; D008855:Microscopy, Electron, Scanning; D010539:Permeability; D019441:Plant Epidermis / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D018515:Plant Leaves / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D018526:Plant Transpiration / Q000502:physiology*; D027861:Prunus / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D014867:Water / Q000378:metabolism*; D014885:Waxes / Q000737:chemistry*
D014885:Waxes; D014867:Water
Cuticular transpiration; Cuticular wax; Leaf surface; Plant cuticle; Wax chemistry