UV-B radiation effects on terrestrial plants – A perspective

Both terrestrial and aquatic plants, the primary producers supporting life on earth, can be threatened by global climate change and particularly by UV-B radiation due to the depletion of the ozone layer in both Poles. The injurious effects of UV-B have been assessed mainly through in vitro studies and vary greatly according the dose received, the exposition period and the sensitivity of the species. Adaptive responses can include for example, synthesis of new compounds, increases of UV-B absorbing compounds or anti-oxidant enzymes. Morphological consequences are also documented such as reduced growth and thickening of leaves and cuticule. The main response of UV-B irradiation in indoor experiments is the formation of UV-B absorbing compounds such as phenolic compounds and flavonoids which function as protective screens, although in the natural habitat plants living at higher altitudes and latitudes are tolerant to UV-B due to the natural selection. The main conclusion derived from studies with terrestrial plants is that photosynthesis is not significantly affected by changes in UV-B radiation when plants grow under natural conditions. Moreover, due to the successful implementation of the Montreal Protocol the increase of UV-B radiation in most populated regions of the world (i.e., outside the regions affected by the Antarctic ozone hole) has been modest.