Cadmium and zinc uptake and translocation in dwarf Polish wheat seedlings as affected by calcium and potassium combination

Combination of calcium and potassium (Ca-K) influences cadmium and zinc uptake and translocation in dwarf Polish wheat (Triticum polonicum), but its effects remain unclear. In the present study, a high concentration of Ca-K reduced uptake of Cd and Zn by roots and promoted their translocations to shoots under Cd and Zn excess. Whatever under a low or high concentration of Ca-K, Zn inhibited Cd uptake and translocation under Cd+Zn stress when compared with Cd stress alone. However, the reduced Cd content caused by Zn under the high concentration of Ca-K was significantly lower than under the low concentration of Ca-K. Under both Ca-K treatments, Cd promoted Zn uptake and inhibited Zn translocation under Cd+Zn stress when compared with those under Zn stress. The high concentration of Ca-K reinforced the promotion of Zn uptake and the inhibition of Zn translocation caused by Cd. The Ca-K or Zn affected the expression of several metal transporters and influenced cell wall metabolism, the subcellular distribution of Cd, and the Cd chemical forms. Meanwhile, Ca-K or Cd also affected the expressions of several metal transporters and changed the subcellular distribution of Zn. The differentially expressed metal transporters and changes in subcellular distributions and Cd chemical forms were associated with Cd and Zn uptake and translocation. In summary, the application of Ca-K caused changes in gene expression, Cd and Zn uptake, translocation, and subcellular distribution.