Cadmium accumulation capacities of Arabis alpina under environmental conditions

Arabis alpina is a perennial Brassicacea closely related to Arabidopsis thaliana. Leaves from plants were collected in bulk from three different places in Switzerland (two in the Jura Mountains, Chasseral and Pichoux and one in the Alps, Schilthorn). The population “sensus lato” growing in Chasseral (Jura) showed more cadmium (Cd) accumulation in leaves than the two others. Interestingly, the soil of Chasseral contains more total and NaNO3 extractable Cd, indicating that Cd accumulation in A. alpina is mainly related to the soil Cd content. These observations were only partly confirmed by physico-chemical parameters of the soils. Global RAPD analyses showed that alpine and Jura plants exhibit genetic divergence which likely not influence plant cadmium uptake as judged by in vitro culture experiments. Interestingly, MRP3 and Nramp4 were differentially regulated in the three population tested. As shown after hydroponic culture in the presence of 10 μM CdCl2, A. alpina is not a Cd hyper-tolerant plant, unlike Thlaspi caerulescens ecotypes or A. halleri, but rather a Cd bio-indicator plant.