Low magnesium status in plants enhances tolerance to cadmium exposure

Abstract

In a transcriptomic study of magnesium (Mg) starvation in Arabidopsis, we identified several genes that were differentially regulated which are involved in the detoxification process of nonessential heavy metals such as cadmium (Cd). • We further tested the impact of low Mg status on Cd sensitivity in plants. Interestingly, a -Mg pretreatment of 7d alleviated the bleaching of young leaves caused by Cd. No or little difference in Cd tissue concentration between the +Mg and -Mg plants was observed, suggesting that lower Cd toxicity was probably not attributable to modified root to shoot translocation. • Mg deficiency also promoted an increase in the iron (Fe) concentration (up to one-fourth) in Cd-treated leaves. Because high Fe concentrations have previously been reported to prevent the harmful effects of Cd, we explored whether Fe homeostasis plays a role in the Mg-Cd interaction. A protective effect of -Mg pretreatment was also observed on Fe starvation. However, Fe foliar spray partially alleviated Cd-induced chloroses, while it almost completely restored chlorophyll content in Fe-deficient leaves. • In conclusion, the protective effect of Mg against Cd toxicity could be attributable partly to the maintenance of Fe status but also to the increase in antioxidative capacity, detoxification and/or protection of the photosynthetic apparatus. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.