Cadmium and zinc partitioning and accumulation during grain filling in two near isogenic lines of durum wheat

Plants can readily accumulate cadmium (Cd), transferring this element to edible leaves, fruits, and seeds. Rice and wheat are among the top crop sources of Cd. Toxic heavy metals like Cd have chemical properties similar to essential micronutrients such as zinc (Zn) and are generally transported in plants by the same transporters as those essential micronutrients. Unfortunately our knowledge of Cd translocation and accumulation in seeds is still unclear. We conducted a partitioning study to assess both the whole plant Cd distribution and accumulation and potential source-sink remobilization during grain filling period in two near-isogenic lines of durum wheat that differ in root to shoot translocation and grain Cd content. We also assessed the role of Zn fertilization in Cd translocation and accumulation in the grains. There was no remobilization of Cd in both lines during grain filling. Although majority of Cd partitioned to the roots in both lines, root to shoot translocation of Cd differed in both lines. In contrast, there were no significant differences in Zn partitioning between the lines and remobilization was observed in different tissues. Although there was some remobilization of Zn, the main source of Cd and Zn is continued uptake and translocation to sources during grain fill.