Cadmium uptake in PEA plants under environmentally-relevant exposures: the risk of food-chain transfer

The present work was designed to analyze cadmium (Cd) accumulation in Pisum sativum L. plants in a late stage of development, after an exposure to environmentally relevant Cd concentrations of 1, 3, and 30 μ mol L ^-1 Cd. Cadmium exposure increased metal and thiol accumulation, not only in roots but also in the aerial organs of the plants. Nonetheless, except for the highest Cd exposure, plants did not show any evidence of Cd toxicity symptoms. Roots were found to be the main organs for Cd accumulation, but seeds also retained Cd, accumulating up to 2 μ g Cd g fw^-1. The parameters related to reproduction, such as anthesis and fruit development, were more sensitive to incipient degrees of stress than the biomass gain itself. When compared to previous works using hydroponic cultures, our results evidenced striking differences in Cd and thiol accumulation, suggesting the importance of using more realistic conditions in Cd-stress studies. The analysis of Cd retention in fruits demonstrated that, even at the lower exposure, Cd levels were higher than those allowed for human consumption, hence posing a serious risk of food-chain transfer and confirming the need for more studies on Cd accumulation in contaminated soils.