Cerium toxicity, uptake and translocation in Arabidopsis thaliana seedlings

Arabidopsis thaliana seedlings were cultivated in 0-500 μmol/L of extraneous cerium (Ce) for 7 d to investigate the toxicity, uptake and translocation of rare earth elements (REEs). The results showed that Ce could be largely absorbed by the roots of A. thaliana and translocated to the shoots. But the uptake rates of Ce by the roots were much higher than the translocation rates from roots to shoots. Ultrastructural analysis revealed that Ce was mainly distributed on the cell wall. At higher concentration, Ce could also enter cell, destroy the ultrastructure of cells and disturb the intrinsic balance of nutrient elements of A. thaliana. Addition of Ce (50-500 μmol/L) to the culture medium significantly inhibited the elongation of primary roots, decreased chlorophyll content, rosette diameter and fresh mass of plants. The damage increased with the increase of Ce concentration in culture medium, although primary root elongation, chlorophyll content, and rosette diameter were stimulated by relatively low concentration (0.5 μmol/L) of Ce. Thus, it is speculated that REEs may become a new type contamination if we donʹt well control the release of REEs into the environment.