ROS metabolism and nutrient uptake are differentially regulated by RBOH C, RBOH D and RBOH F under cadmium toxicity

LM SANDALIO; DK GUPTA; LB PENA; AJ HERNÁNDEZ; M INOUHE; M SANZ-FERNÁNDEZ; C HAFSI; MC ROMERO-PUERTAS

Oviedo

Congreso; XXIII Reunión de Biología Molecular de Plantas; 2016

Cadmium (Cd) is toxic for plants, animals and humans. In plants, Cd-specific transporters have not been identified and Cd seems to be transported via several classes of Ca2+, Fe2+ and Zn2+ transporters, affecting their uptake and distribution and therefore inducing deficiency of those elements (Clemens 2006). In plants Cd can cause disturbances in photosynthesis and growth inhibition (Sandalio et al. 2001). Oxidative stress is one of the primary effects of Cd exposure, although the sources of reactive oxygen species involved are not well established. In this work, 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. A cadmium-dependent reduction of growth was observed in WT, AtrbohC and D, but not in AtrbohF. H2O2 and lipid peroxidation content increased with the time of Cd exposure 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 all Atrbohs, while glutathione reductase and glycolate oxidase activities increased in Atrboh mutants, and superoxide dismutases were down-regulated specifically in AtrbohC. The redox couples GSH/GSSG and ASA/DHA differentially changed in AtrbohC and AtrbohF, respectively. The translocation of Cd to the leaves was severely reduced in Atrboh mutants mainly after 1 d of treatment. Similar results were observed for S, P, Ca, Zn and Fe accumulation, while an opposite trend was observed for K accumulation, except in AtrbohF. The regulation of several K and Fe transporters by RBOH will be disused. In conclusion, under Cd stress RBOHs differentially regulate ROS metabolism, redox homeostasis, and nutrient balance. This result could be of potential interest in biotechnology for the phytoremediation of polluted soils.