UV-B RESISTANCE OF PLANTS GROWN IN NATURAL CONDITIONS

Plants protect themselves against potentially harmful effects of solar ultraviolet-B radiation by a variety ofmechanisms conferring UV-B resistance. The underlying resistance mechanisms of a plant can be acclimated corresponding to the prevailing UV-B exposure in their habitat such that under natural conditions UV-B damage does not seem to exist. UV-B resistance is not only induced by UV-B radiation but to a large extent also by other environmental factors. Here, we review current evidence on how abiotic variables, e.g. low temperature or water deficit, affect UV-B resistance mechanisms. We are focusing on acclimation of UV-B screening through the accumulation of UV absorbing compounds, which is well investigated, and on the removal of UV-B-induced DNA damage by repair. Although the latter is a resistance mechanism specifically directed to UV-B-induced damage, it is strongly under investigated. Interaction of UV-B radiation and other environmental factors can occur at the level of signal transduction chains, most often leading to cross-resistance. Additionally, the influence of environmental conditions on physiological reactions may lead either to cross-resistance or cross-sensitivity.