ABSTRACT
Philip J. White The James Hutton Institute, UK King Saud University, Riyadh, Kingdom of Saudi Arabia
1 INTRODUCTION
Selenium is an essential mineral element for human and animal nutrition but it is not required by plants (White & Broadley, 2009). Since most Se in human diets is derived from plant products, insufficient dietary Se is generally attributed to crop production on soils with low Se content or phytoavailability. At the opposite extreme, excess Se is harmful to humans and can be toxic to most plants (White et al., 2004). The concentration and chemical forms of Se in natural soils are primarily determined by geology (White et al., 2007b). Selenium concentrations in most soils lie between 0.01-2.0 mg/kg but soils associated with particular geological features can reach 1200 mg/kg. Selenate (SeO2−4 ) is the dominant Se species in solution in most cultivated soils, although selenite (SeO2−3 ) dominates under anaerobic and acidic conditions, such as in paddy soils. Selenium concentrations in crops can be increased simply by the application of Se-fertilisers. This article first provides an overview of Se uptake and metabolism in flowering plants (angiosperms) then describes genetic variation in Se uptake and accumulation between and within angiosperm species.
