Influence of low calcium availability on cadmium uptake and translocation in a fast-growing shrub and a metal-accumulating herb

Calcium (Ca) and the toxic heavy metal cadmium (Cd) are antagonistic ions competing for uptake in plants when they co-occur in soil solutions, and high Ca concentrations can reduce the uptake of Cd in plants. However, less is known about the effects of low Ca bioavailability on Cd uptake and translocation in plants. In a recent study published in AoB PLANTS, Eller and Brix analyzed whether low Ca availability, as compared to high Ca availability, increased the accumulation of cadmium in Brassica juncea and Sesbania sesban. The cadmium uptake was indeed increased in the roots of both species, but not in the shoots. The translocation of Cd to the shoots is a complex process that seemed to be less affected by external ion concentrations and activities. As both species’ viability was low under low calcium and high cadmium, the harvestable biomass limited the amount of Cd that could potentially be removed from polluted media by harvesting.