Attenuation of UV radiation by plant cuticles from woody species

Abstract

Transmittance spectra of isolated plant cuticles were measured in the wavelength range from 270 to 600 nm. The cuticles were enzymatieally isolated from the leaves of 27 species (26 evergreen or deciduous woody, one succulent herhaceous) and from four species of fruits. With the exception of subtropical and tropical species all plants were cultivated in the field. The cuticles of the species studied strongly attenuated ultraviolet (UV) radiation at wavelengths < 400 nm while they were practically translucent in the visible range. Relatively broad transmittance minima occurred at wavelengths from 280 to 320 nm (UV-B). Spectral transmittances at 300 nm ranged from 0-004 (Hex aquifoliuin) to 0-50 (Primus avium) for leaf cuticles and from 0-00023 (Cydoitia obtonga) to 0-005 (Matus domeslica) for fruit cuticles. The constitutive UV protection by cuticular pigments may be supplemented, to varying degrees, by pigments located in the epidermal cell wall and protoplast. Thus, it is concluded that only a small fraction of incident UV-B radiation may actually reach the sensitive tissues of the leaves of non-herbaceous species and of fruits.

Solar UV Upregulates Photoprotection but Slows Photosynthesis in Subalpine Australian Plants

“…Removing exposure to UV did not instigate any structural change in our three study species over the course of our study period. Although this contrasts with some reports (Grammatikopoulos et al, 1998), it is consistent with strong co-regulation of leaf anatomy by light intensity (Krauss et al, 1997;Liakopoulos et al, 2006), which is also intense in subalpine areas. Leaves of E. pauciflora have thick cuticles and thick epidermal layers and exhibit strong structural screening against UV (Day et al, 1992).…”

The Formation and Function of Plant Cuticles

“…These include a variety of soluble flavonoid pigments that are typically localized within the vacuoles of epidermal cells, phenolic compounds present in the polysaccharide cell wall, and lipophilic phenolic molecules that are covalently bound to cutin or associated with waxes (Pfündel et al, 2006). A survey of isolated cuticles from a range of species indicated generally effective screening of the UV-B spectrum but consistently high transmittance in the higher wavelengths that are photosynthetically active (Krauss et al, 1997). In addition to absorbing light, the plant cuticle can reflect light to some degree, presumably depending on the abundance of epicuticular wax crystals.…”

Flavonoids accumulate in leaves and glandular trichomes of Phillyrea latifolia exposed to excess solar radiation

“…1d) might attenuate the major proportion of the UV radiation reaching physiological targets Day et al, 1984). The synthesis of flavonoids has been suggested to be confined to cells of epidermal layers (Schmelzer et al, 1988) and the accumulation of flavonoids in the epidermal layers of sun leaves has been reported as constituting a primary adaptation of several species to the impact of short-wave radiation from the sun (Krauss et al, 1997). However, the fact that flavonoids accumulated in the mesophyll tissue of P. latifolia leaves acclimated to full solar irradiance (i.e.…”