Variability in Cadmium Uptake in Common Wheat under Cadmium Stress: Impact of Genetic Variation and Silicon Supplementation

To decrease the transfer of cadmium (Cd) to the food chain, it is essential to select wheat (Triticum aestivum L.) germplasm that accumulates the least amount of Cd and to develop management practices that promote a reduction in Cd uptake. This requires knowledge of factors controlling Cd accumulation in wheat plants, which are not fully understood. The aim of this study was thus to investigate variations in Cd accumulation, translocation, and subcellular distribution in response to Cd stress and supplemental Si in two wheat cultivars that have high vs. low Cd accumulation capacities. Cd uptake and distribution in two common wheat cultivars, high-Cd 'LCS Star' and low-Cd 'UI Platinum' were evaluated at two levels of Cd (0 and 50 mu M) and Si (0 and 1.5 mM) in a hydroponic experiment. LCS Star and UI Platinum were not different in root Cd accumulation but differed in Cd concentration in the shoot, which agreed with the variation between the two cultivars in their subcellular Cd distributions in organelle and soluble fractions as well as induced glutathione synthesis in response to Cd addition. Supplemental Si reduced Cd uptake and accumulation and suppressed Cd-induced glutathione synthesis. The differences between the wheat cultivars in Cd accumulation in shoots mainly derive from root-to-shoot translocation, which is related to subcellular Cd distribution and Cd-induced glutathione synthesis. Exogeneous Si could decrease Cd translocation from root to shoot to alleviate Cd toxicity in common wheat.