Silicate reduces cadmium uptake into cells of wheat. (April 2016)

• Record Type: Journal Article
• Authors: Greger, Maria; Kabir, Ahmad H.; Landberg, Tommy; Maity, Pooja J.; Lindberg, Sylvia
• Is Part Of: Environmental pollution. Volume 211(2016)
• Page Start: 90
• Page End: 97
• Publication Date: 2016-04
• Subjects: Cadmium uptake -- HMA2 -- LCT1 -- Membrane transport -- Phytochelatin -- Wheat; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2015.12.027
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Cadmium (Cd) is a health threat all over the world and high Cd content in wheat causes high Cd intake. Silicon (Si) decreases cadmium content in wheat grains and shoot. This work investigates whether and how silicate (Si) influences cadmium (Cd) uptake at the cellular level in wheat. Wheat seedlings were grown in the presence or absence of Si with or without Cd. Cadmium, Si, and iron (Fe) accumulation in roots and shoots was analysed. Leaf protoplasts from plants grown without Cd were investigated for Cd uptake in the presence or absence of Si using the fluorescent dye, Leadmium Green AM. Roots and shoots of plants subjected to all four treatments were investigated regarding the expression of genes involved in the Cd uptake across the plasma membrane (i.e. LCT1 ) and efflux of Cd into apoplasm or vacuole from the cytosol (i.e. HMA2 ). In addition, phytochelatin (PC) content and PC gene ( PCS1 ) expression were analysed. Expression of iron and metal transporter genes ( IRT1 and NRAMP1 ) were also analysed. Results indicated that Si reduced Cd accumulation in plants, especially in shoot. Si reduced Cd transport into the cytoplasm when Si was added both directly during the uptake measurements and to the growth medium. Silicate downregulated LCT1 and HMA2 and upregulated PCS1 . In addition, Si enhanced PC formation when Cd was present. The IRT1 gene, which was downregulated by Cd was upregulated by Si in root and shoot facilitating Fe transport in wheat. NRAMP1 was similarly expressed, though the effect was limited to roots. This work is the first to show how Si influences Cd uptake on the cellular level. Graphical abstract: Highlights: Si decreases accumulation and translocation of Cd in plants at tissue level. This work is the first to show how Si influences Cd uptake. Si decreases Cd uptake into cell and downregulates heavy metal transporter LCT1. Si downregulates HMA2 transporter, which regulates Cd transport from root to shoot. Si increases phytochelatin formation, tying up free Cd, preventing toxic effects. Abstract : Silicate reduces Cd uptake into cytosol, Cd translocation to shoot by downregulating membrane transporters in wheat and increases phytochelatin formation decreasing free Cd in cytosol.