Water stress generates an oxidative stress through the induction of a specific Cu/Zn superoxide dismutase in Lotus corniculatus leaves

Drought brings about different biochemical responses in plants in order to minimize its deleterious effects. Drought induces an oxidative stress in Lo tus corniculatus leaves, measured as an increment in lipid membrane peroxid ation and in situ detected superoxide. As a result, total superoxide dismut ase (SOD: E.C. 1.15.1.1) activity increases after a 4-h drought, when the h ydric potential has decreased to -0.77 MPa. Assays with specific inhibitors suggest the presence of MnSOD, Cu/ZnSOD and FeSOD activity in L. cornicula tus plants. contribute 60, 30 and 10% of total SOD activity, respectively. The Cu/ZnSOD isoform proved to be the most responsive to drought showing a remarkable increase in its activity as that corresponds to the induction of three different isoenzymes. Expression analysis of SOD isoforms revealed a n increase in Cu/ZnSOD transcripts with a maximum accumulation 4 h after dr ought imposition. The possible role of SOD enzymes as an antioxidant protec tor system under water stress conditions in L. corniculatus is discussed. ( C) 2001 Elsevier Science Ireland Ltd. All rights reserved.