Cadmium build-up and the depletion of the ozone layer are causing irreparable damage to plants, say researchers in Spain.

Javier Martínez-Abaigar and colleagues from the Universidad de La Rioja have found that a plant's ability to repair DNA damage caused by UV-B radiation is impaired by cadmium accumulation. Repair of DNA damage is essential for plants to survive. 

Martínez-Abaigar's team studied the responses of an aquatic plant called liverwort to the individual and combined effects of cadmium and UV radiation. They found that both triggered the plant to produce increased amounts of antioxidants, but that the plant produced the highest levels when the effects were combined. DNA damage was provoked specifically by UV-B radiation, whereas cadmium had modest effects in this respect, said Martínez-Abaigar. However, the strongest DNA damage was recorded in the presence of both UV-B and cadmium. 

Cadmium is released into soils through natural weathering of minerals, but it is also released artificially, for example from fertilisers and during waste incineration. When plants grow in these soils they take up the metal and it accumulates. Cadmium is known to be toxic to plants but this research shows that it also intensifies the effects of UV-B radiation, said Martínez-Abaigar. 

The team will continue to use aquatic plants to study the effects of UV-B radiation. Over the past 25 years levels of UV-B radiation have increased as the ozone layer has depleted, said Martínez-Abaigar, and studies such as this are 'increasingly important.' 'Predicted changes show the ozone layer will remain vulnerable to further depletion in the near future.' 

Elinor Richards