The role of NADPH oxidases under cadmium (Cd) toxicity was studied using Arabidopsis
thaliana mutants AtrbohC, AtrbohD and AtrbohF, which 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 H2 O2 and lipid peroxidation
was observed in all genotypes, with AtrbohC showing 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
in AtrbohC. The GSH/GSSG and ASA/DHA couples were also affected by the treatment,
principally in AtrbohC and AtrbohF, respectively. Cadmium translocation to the leaves
was severely reduced in Atrboh mutants after 1 day of treatment and even after 5 days
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.