Ecology of Selenium in Plants

Abstract

Selenium (Se) is both essential at low levels and toxic at higher levels to most organisms. Plant Se accumulation therefore may affect interactions with ecological partners positively or negatively. The ecological implications of plant Se accumulation are especially intriguing for Se hyperaccumulator species, which have evolved the capacity to take up Se to extraordinarily high levels, around 1% of dry weight. In this chapter, we summarize ecological aspects of Se in plants, including how Se can act as a defense mechanism against herbivores, how some herbivores have disarmed this defense, how Se can be transferred to higher trophic levels, how Se hyperaccumulating plants alter soil Se distribution and speciation around them and how this affects other plant species. The effects of plant Se on plant-microbe interactions are not reviewed here, since they are covered elsewhere. Insight into ecological implications of plant Se accumulation sheds light on evolutionary pressures that led to Se hyperaccumulation, and the importance of plant Se (hyper)accumulation for Se cycling. In addition, better understanding of the ecological impacts of Se in plants can help manage seleniferous habitats and optimize crop Se biofortification and the use of plants in phytoremediation to clean up Se polluted areas.