Light Intensity and Temperature Effects on Epicuticular Wax Morphology and Internal Cuticle Ultrastructure of Carnation and Brussels Sprouts Leaf Cuticles1

Abstract

At either 440 or 145 μEm −2 s −1 , greater amounts of cuticle, cutin matrix, and wax were formed at 15° than 25°C on leaves of Brussels sprouts ( Brassica oleraceae . L., Gemmifera group), but the reverse occurred on leaves of carnation ( Dianthus caryophyllus L.). At either 15 or 25°, greater amounts of cuticle, cutin matrix, and wax were formed at 440 than 145 μEm −2 s −1 on both species. For Brussels sprouts, at 25°/440 μEm −2 s −1 and 25°/145 μEm −2 s −1 , large parallel wax dentrites covered the leaf surface. At 15°/440 μEm −2 s −1 , dentrites were smaller and morphologically less elaborate. At 15°/145 μEm −2 s −1 , epicuticular wax occurred as scattered rods perpendicular to the leaf surface. Carnation epicuticular waxes consistently occurred as rods, but as temperature and/or light intensity decreased, rod length decreased and density increased. There were no changes in internal cuticle ultrastructure of either species in different environments, but cuticle thickness increased as temperature and light intensity decreased. Epicuticular waxes visualized in surface view by scanning electron microscopy (SEM) were extracted by procedures for transmission electron microscopy (TEM) observation.