Figure 1.

Sunlight absorption by Arabidopsis cell compounds. Most sunlight visible wavelengths penetrate the atmosphere, whereas harmful UV-C and part of UV-B/A are absorbed by ozone in the atmosphere. Photosynthetic pigments, such as the carotenoids and chlorophyll a and b (Chla/b) harvest photons in the 400- to 700-nm waveband, which correspond to photosynthetically active radiations (PAR). A battery of nuclear photoreceptors sensitive to blue, red, far-red, or UV-B light trigger specific adaptations of plant development and metabolism to the local environment. Finally, aromatic DNA bases and methylated cytosines absorb light in the UV waveband, enhancing DNA susceptibility to genotoxic damages and mutations. Adapted from Fondriest Environmental, Inc., (2014) and from Kami et al. (2010).