1 Selenium Supply Alters Subcellular Distribution and Chemical Forms of Cadmium and Expression of Transporter Genes Involved in Cadmium Uptake and Translocation in Winter Wheat (Triticum Aestivum)

Abstract Background Cadmium (Cd) accumulation in crops will affect the yield and quality of crops, and also harm human health. The application of selenium (Se) can reduce the absorption and transport of Cd in winter wheat. Results The result showed that increasing Se supply significantly decreased Cd concentration and accumulation in shoots and roots of winter wheat, and the root to shoot translocation of Cd. The Se supply increased the root length, surface area and root volume, but decreased the root average diameter. Increasing Se supply significantly decreased Cd concentration in cell wall, soluble fraction and cell organelle in roots and shoots. An increase of Se supply inhibited Cd distribution in the organelle of shoot and root, but enhanced Cd distribution in the soluble fraction of shoot and the cell wall of root. The Se supply also decreased the proportion of active Cd (ethanol-extractable (FE) Cd and deionized water-extractable (FW) Cd) in roots. In addition, the expression of TaNramp5-a, TaNramp5-b, TaHMA3-a, TaHMA3-b and TaHMA2 were significantly increased with the increase of Cd concentration in roots, and the expression of TaNramp5-a, TaNramp5-b and TaHMA2 in roots were down-regulated by increasing Se supply, regardless of Se supply or Cd stress, respectively. The expression of TaHMA3-b in root was significantly down-regulated by Se10 treatment at both Cd5 and Cd25 but up-regulated by Se5 treatment at Cd25. The expression of TaNramp5-a, TaNramp5-b, TaHMA3-a, TaHMA3-b and TaHMA2 in shoot were down-regulated by increasing Se supply at Cd5, and Se5 treatment up-regulated the expression of those genes in shoot at Cd25. Conclusions The results confirm that Se application limit Cd accumulation in wheat via regulating subcellular distribution and the chemical forms of Cd in tissues of winter wheat, as well as the expression of TaNramp5-a, TaNramp5-b and TaHMA2 in root.