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Salt stress induces up‐regulation of an efficient chloroplast antioxidant system in the salt‐tolerant wild tomato species Lycopersicon pennellii but not in the cultivated species
Author(s) -
Mittova Valentina,
Tal Moshe,
Volokita Micha,
Guy Micha
Publication year - 2002
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2002.1150309.x
Subject(s) - chloroplast , apx , lycopersicon , glutathione reductase , antioxidant , lipid peroxidation , biochemistry , superoxide dismutase , peroxidase , oxidative stress , biology , glutathione , paraquat , proline , chemistry , glutathione peroxidase , botany , enzyme , amino acid , gene
The response of the chloroplastic antioxidant system of the cultivated tomato Lycopersicon esculentum (Lem) and its wild salt‐tolerant related species L. pennellii (Lpa) to NaCl stress was studied. An increase in H 2 O 2 level and membrane lipid peroxidation was observed in chloroplasts of salt‐stressed Lem. In contrast, a decrease in these indicators of oxidative stress characterized chloroplasts of salt‐stressed Lpa plants. This differential response of Lem and Lpa to salinity, correlates with the activities of the antioxidative enzymes in their chloroplasts. Increased activities of total superoxide dismutase (SOD), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), glutathione‐S‐transferase (GST), phospholipid hydroperoxide glutathione peroxidase (PHGPX) and several isoforms of non‐specific peroxidases (POD) were found in chloroplasts of salt‐treated Lpa plants. In these chloroplasts, in contrast, activity of lipoxygenase (LOX) decreased while in those of salt‐stressed Lem it increased. Although total SOD activity slightly increased in chloroplasts of salt‐treated Lem plants, differentiation between SOD types revealed that only stromal Cu/ZnSOD activity increased. In contrast, in chloroplasts of salt‐treated Lpa plants FeSOD activity increased while Cu/ZnSOD activity remained unchanged. These data indicate that salt‐dependent oxidative stress and damage, suffered by Lem chloroplasts, was effectively alleviated in Lpa chloroplasts by the selective up‐regulation of a set of antioxidative enzymes. Further support for the above idea was supplied by leaf discs experiments in which pre‐exposure of Lpa plants to salt‐treatment conferred cross‐tolerance to paraquat‐induced oxidative stress while increased oxidative damage by paraquat‐treatment was found in salt‐stressed Lem plants.