The maize epicuticular wax layer provides UV protection

As surface ultraviolet-B (UV-B) radiation levels increase due to the decline in the protective stratospheric ozone layer, ultraviolet radiation sunscreens will become more important for all plant species that grow in sunlight. Epicuticular waxes, which cover the aerial portions of all terrestrial plants, are ideally located to be sunscreens. The sun-screening ability of maize (Zea mays L.) epicuticular waxes was tested using the glossy1 mutant, which is specifically defective in juvenile wax production. A significant difference between the glossy1 mutant and wild type was seen in UV-induced leaf rolling and in some measurements of UV-induced DNA damage levels under enhanced UV. Isolated epicuticular wax layers absorbed significant amounts of UV, and leaves with wax absorbed more UV than leaves with little wax. Thus, by some measures, the epicuticular waxy layer acts as an ultraviolet radiation protectant in maize.