Mechanisms of phytoextraction in Cynara cardunculus L. Growing under cadmium and arsenic stress

Phytoextraction is a remediation strategy, which employs plants to remove heavy metals and other contaminants from the soil. The aim of this study was to evaluate the ability of the cardoon (Cynara cardunculus L. var. altilis) to grow under cadmium (Cd) and arsenic (As) stress and accumulate them in tissues. Pot trials were carried out under controlled environment conditions and were exposed to As (0, 6.5, 13 mM), Cd (0, 6.5, 13 mM) and As+Cd (0+0, 6.5+6.5, 13+13 mM) up to 60 days. In cardoon, the biomass production and Cd and As concentrations were determined in 4 different stages of the biological cycle in different parts of plant. Under Cd treatment, the Cd concentration decreased in the roots while increased in the leaves over time. After 15 days of treatment, the plants treated with As, showed a severe reduction in the production of biomass. The growth is inhibited at high doses of this element and the plants died. The results show a rapid uptake of arsenic by the roots and its accumulation in the aerial parts of the plant. The As concentration in cardoon tissues increased with increasing As concentration. In the combined Cd and As treatments the plants improved resistance to As and Cd. The presence of Cd increased the ability of cardoon to translocate As from the root to the shoot. Also cardoon in Cd+As treatment was more tolerant to As (up to 45 days) compared to As alone and increased its ability to phytoextraction.