Transformed tobacco plants expressing a rice cysteine proteinase inhibitor (OC‐I) and non‐transformed plants were grown in a controlled environment and subjected to various stresses. Two‐month‐old transformed and non‐transformed plants were exposed for 5 days to drought conditions by withholding watering. High temperature (40 °C) was applied additionally at day 6th for 5 h either individually or in combination with drought. All stress treatments were applied under low (150 μmol m−2 s−1 PPFD) and high light intensity (HL) of 1000 μmol m−2 s−1 PPFD to determine if OC‐I expression might provide protection under combination of stresses usually existing in nature. Drought stress led to diminution in leaf relative water content, photosynthesis inhibition, decrease in chlorophyll content and accumulation of malondialdehyde and proline. Heat stress alone did not affect the plants significantly, but intensified the effect of drought stress. HL intensity further increased the proline content. OC‐I transformed plants grown under low light intensity had significantly higher total superoxide dismutase and guaiacol peroxidase activities as well as their isoforms than non‐transformed control plants under non‐stress and stress conditions. Catalase activity was not highly affected by OC‐I expression. Results indicate that OC‐I expression in tobacco plants provides protection of the antioxidative enzymes superoxide dismutase and guaiacol peroxidise under both non‐stress and stress conditions.
Barley seedlings were pre-treated with 1 and 5 µM H 2 O 2 for 2 d and then supplied with water or 150 mM NaCl for 4 and 7 d. Exogenous H 2 O 2 alone had no effect on the proline, malondialdehyde (MDA) and H 2 O 2 contents, decreased catalase (CAT) activity and had no effect on peroxidase (POX) activity. Three new superoxide dismutase (SOD) isoenzymes appeared in the leaves as a result of 1 µM H 2 O 2 treatment. NaCl enhanced CAT and POX activity. SOD activity and isoenzyme patterns were changed due to H 2 O 2 pre-treatment, NaCl stress and leaf ageing. In pre-treated seedlings the rate of 14 CO 2 fixation was higher and MDA, H 2 O 2 and proline contents were lower in comparison to the seedlings subjected directly to NaCl stress. Cl -content in the leaves 4 and 7 d after NaCl supply increased considerably, but less in pre-treated plants. It was suggested that H 2 O 2 metabolism is involved as a signal in the processes of barley salt tolerance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.