Over the past few decades, there has been a depletion of the stratospheric ozone layer due to
emissions of halogen-containing compounds of anthropogenic origin. This has resulted in a
concomitant increase in solar ultraviolet-B radiation. High levels of UV-B radiation are responsible for
multiple biologically harmful effects in both plants and animals. In plants, these effects include DNA
damage, which often causes heritable mutations affecting various physiological processes, including
the photosynthetic apparatus, protein destruction and signal transduction via UV-B photoreceptors.
High UV-B levels introduce a number of different lesions, predominantly cyclobutane pyrimidine
dimmers (CPDs) and pyrimidine (6-4) pyrimidinone products [(6-4) PPs] in the genome. These could
adversely affect plant growth, development and morphology, especially the productivity of sensitive
crop species. This paper reviews the genetic effects of long-term UV-B exposure in plants.