Progresses on selenium metabolism and interaction with heavy metals in higher plants

Selenium (Se) is an essential element for many organisms and toxic when its concentration elevated. As plants are the main source of dietary Se, plant Se metabolism therefore is important for Se nutrition of human and the Se status in the ecosystem. Plant Se uptake and metabolism can be exploited for the purposes of developing Se-enriched crop cultivars (biofortification) and reducing the health risk of heavy metals. Here we summarize the concentration, forms, distribution and bioavailability of Se in the soil, which predetermines the accumulation of Se by plants. We also review the main knowledge of Se uptake and metabolism in the higher plant underpinning Se biofortification strategies and antagonism to heavy metals. Two complementary biofortification approaches including agronomic approaches and genetic approaches, which have been successfully adopted to increase the concentrations of Se in plant food, are also discussed. In addition, the interaction between Se and heavy metals was present in order to provide comprehensive perspective. In the end, related hotspot problems on the aspect of Se metabolism and biofortification were proposed to help in the better management of the agricultural production of Se-rich crops for biofortification.