Soil application of manganese sulfate could reduce wheat Cd accumulation in Cd contaminated soil by the modulation of the key tissues and ionomic of wheat.

Wheat is one of the main sources of dietary Cd in northern China, and the reduction of Cd accumulation in wheat is of great significance for human health. This study explored and highlighted the effects of soil application of manganese sulfate (MnSO4) on the distribution and transport of Cd in two wheat cultivars, and identified the key tissues and elements during the Cd translocation in wheat by measuring the concentrations of eight elements in 17 parts of wheat under MnSO4 treatment. The bioaccumulation factor of Cd in the roots and the translocation factor of Cd in node1 (connected to the panicle) of the high-Cd wheat cultivar were found to be higher than that of the low-Cd wheat cultivar. Soil application of MnSO4 (0.05-0.2%) significantly reduced the Cd concentration in high- and low-Cd wheat grains by 24.16-57.52% and 25.90-63.44%, respectively, and decreased the Cd concentrations in all wheat tissues. MnSO4 application had no effect on wheat growth, and the inhibition effects on wheat Cd accumulation were more pronounced at wheat-seeding stage. MnSO4 application inhibited Cd uptake by the ion antagonism between Mn/Zn/Fe and Cd in the wheat roots and reduced Cd upward transport by reducing the Cd transport from node1 to internode1 and from panicle to wheat grain. Nodes 2-4 can restrict the transport of both Cd and Mn, whereas node1 and the panicle can inhibit Cd transport but have no effect on Mn transport. The ionomic results show that the overall spatial distribution of different tissues is consistent with the growth morphology of wheat plants. MnSO4 application significantly changed the ionomes of the roots, nodes, glumes, and wheat grains; meanwhile, the differences in the ionomic responses among the roots are the most remarkable. The results of this study show that soil application of MnSO4 is efficient for reducing the Cd accumulation in wheat grown in Cd-contaminated soil, demonstrating wide application potential.