Uptake and translocation of CuEDDS complexes by Brassica carinata

The knowledge of the mechanisms that underlie metal complex uptake may lead to the development of new strategies for enhancing metal phytoextraction. As metals such as copper are actively taken up by roots, by inhibiting the proton driving force it is possible to obtain preliminary indications on the metal complex uptake mechanism. For this, Cu, EDDS, and Cu-EDDS uptake kinetics of Brassica carinata excised roots incubated in 30 and 150 microM solutions of either the metal, the chelant, and the complex were determined in the presence or not of the ATPase inhibitor vanadate. Following both Cu and CuEDDS treatments, metal uptake was negatively influenced by vanadate, whereas EDDS uptake did not, suggesting that Cu and the chelant did not enter the roots in their complexed form but by two different routes. The incubation in the same solutions of B. carinata intact plants showed that, differently from Cu, EDDS was largely translocated to shoots, but its low concentration resulted in a Cu to EDDS molar ratio ranging from 2 to 4 depending on metal complex concentration in the solution confirming that the uptake pathways of the two compounds were different.