Platinum uptake, distribution and toxicity in Arabidopsis thaliana L. plants

- Pt is taken up by roots and easily translocated to the rosette.
- The amount of Pt in the rosette is substantially higher than in roots.
- Effect of Pt on plants is stimulatory at low concentrations, but otherwise toxic.
- Dose-response relationship between Pt and plant performance is hormesis-like.
- High concentrations of Pt impair plant morphology, physiology and biochemistry.

Platinum (Pt) occurs at very low levels in parent rock and soils in unpolluted areas, however concentrations of this element in urban areas is steadily increasing. At the levels recorded in urban environments, Pt is not yet phytotoxic, but it already poses a threat to human health, particularly when present in airborne particulate matter. In this study an attempt was made to evaluate Pt(II) uptake, distribution and toxicity in Arabidopsis thaliana L. plants.Arabidopsis thaliana plants were hydroponically grown with increasing Pt(II) concentrations in the range of 0.025-100 µM. Pt(II) was taken up by the roots and translocated to the rosette. At lower Pt(II) concentrations (≤ 2.5 μM) hormesis was recorded, plant growth was stimulated, the efficiency of the photosynthetic apparatus improved and biomass accumulation increased. Higher Pt(II) concentrations were phytotoxic, causing growth inhibition, impairment of the photosynthetic apparatus, membrane injuries and a reduction in biomass accumulation. Exposure of A. thaliana to Pt(II) also resulted in an increased content of phytochelatins throughout the plant and glutathione in the rosette.Uptake and translocation of Pt(II) to harvestable organs of A. thaliana suggests that species of higher biomass accumulation from the Brassicaceae family can probably be used for the phytoextraction of Pt-polluted sites.

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