NADPH oxidases differentially regulate ROS metabolism and nutrient uptake under cadmium toxicity

Abstract

The role of NADPH oxidases under cadmium (Cd) toxicity was studied using Arabidopsis thaliana mutants AtrbohC, AtrbohD and AtrbohFwhich were grown under hydroponic conditions with 25 and 100 μM Cd for 1 and 5 days. Cadmium reduced the growth of leaves in WT,AtrbohC and D, but not in AtrbohF. A time-dependent increase in H2O2 and lipid peroxidation was observed in all genotypes, with AtrbohCshowing the smallest increase. An opposite behaviour was observed with NO accumulation. Cadmium increased catalase activity in WT plants and decreased it in Atrboh mutants, while glutathione reductase and glycolate oxidase activities increased in Atrboh mutants, and superoxide dismutases were down-regulated inAtrbohC. The GSH/GSSG and ASA/DHA couples were also affected by the treatment, principally inAtrbohC and AtrbohF, respectively. Cadmium translocation to the leaves was severely reduced in Atrboh mutants after 1 d of treatment and even after 5 d in AtrbohF. Similar results were observed for S, P, Ca, Zn and Fe accumulation, while an opposite trend was observed for K accumulation, except in AtrbohF. Thus, under Cd stress, RBOHs differentially regulate ROS metabolism, redox homeostasis, and nutrient balance and could be of potential interest in biotechnology for the phytoremediation of polluted soils.