Resistance to Selenium Toxicity

Selenium (Se) is a naturally occurring element commonly found in sedimentary rocks. Although there is no concrete evidence that selenium is essential for survival of plants, several studies have shown that it is a beneficial element especially for certain species. Like other nutrients, however, excessively high levels of Se are toxic for most plants. A group of scientists from the US and Japan has determined the mechanism by which plants regulate selenite resistance.

Because of its similarity with sulfur, selenium is metabolized by sulfur metabolic pathways. When plants are exposed to high levels of Se, protein synthesis is adversely affected. Se, instead of sulfur, is attached to the amino acids cysteine and methionine (sulfur-containing amino acids). The scientists discovered that the phytohormones ethylene and jasmonic acid play important roles in regulating selenite resistance. Reactive oxygen species (ROS) were also found to be increased by selenium. Knowing more about factors limiting plant Se accumulation and resistance may have applications for breeding Se-fortified foods, or for phytoremediation.

The abstract of the paper and links to the full article are available at http://www.plantphysiol.org/cgi/content/abstract/pp.107.110742v1