Proline antioxidant role in the common ice plant subjected to salinity and paraquat treatment inducing oxidative stress

Proline antioxidant role in the common ice plant subjected to salinity and paraquat treatment... Leaves of 4-week-old (juvenile) and 9-week-old (adult) plants of the halophyte Mesembryanthemum crystallinum L. (the common ice plant), cultured under controlled conditions in the phytotron, were treated with paraquat (0.1 μM), which produces superoxide radical, and (or) paraquat combined with introduction of NaCl (100 mM) or proline (5 mM) into nutrient medium. After a 20-h dark period (23°C), plants were transferred into light (4 h at 54.1 W/m2 of photosynthetically active radiation) for stimulation of O° 2 − formation in plastids. Activities of antioxidant enzymes, the contents of MDA, H2O2, chlorophyll, and free proline were measured in leaves. Plant responses in two age groups, which differed in the type of photosynthesis (juvenile plants had C3 type of photosynthesis, whereas adult plants were at the transition stage to Crassulacean Acid Metabolism (CAM) photosynthesis), differed in the levels of constitutive proline and proline, induced by NaCl and paraquat, as well as in activities of superoxide dismutase (SOD) and catalase. Changes in SOD activity and proline accumulation in response to paraquat treatment combined with NaCl revealed opposite dependence to accumulation of proline: the more proline accumulated in leaves, the lower activity of the enzyme. In response to paraquat treatment, the content of chlorophylls a and b most drastically declined in juvenile plants. Negative effect of salinity on the content of chlorophylls was lower than that of paraquat and was almost the same in plants of both age groups. Protective effect of exogenous proline was most profound in the case of paraquat treatment. Exogenous proline decreased the rate of lipid peroxidation, the content of superoxide radical and, consequently, SOD activity (almost fivefold), and increased the content of chlorophylls (a and b) in leaves of adult plants. The obtained data suggest that stress-induced accumulation of proline in the common ice plant has both osmoprotectory and antioxidant functions. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Russian Journal of Plant Physiology Springer Journals

Proline antioxidant role in the common ice plant subjected to salinity and paraquat treatment inducing oxidative stress

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Publisher
Springer Journals
Copyright
Copyright © 2009 by Pleiades Publishing, Ltd.
Subject
Life Sciences; Plant Sciences ; Plant Physiology
ISSN
1021-4437
eISSN
1608-3407
D.O.I.
10.1134/S1021443709050124
Publisher site
See Article on Publisher Site

Abstract

Leaves of 4-week-old (juvenile) and 9-week-old (adult) plants of the halophyte Mesembryanthemum crystallinum L. (the common ice plant), cultured under controlled conditions in the phytotron, were treated with paraquat (0.1 μM), which produces superoxide radical, and (or) paraquat combined with introduction of NaCl (100 mM) or proline (5 mM) into nutrient medium. After a 20-h dark period (23°C), plants were transferred into light (4 h at 54.1 W/m2 of photosynthetically active radiation) for stimulation of O° 2 − formation in plastids. Activities of antioxidant enzymes, the contents of MDA, H2O2, chlorophyll, and free proline were measured in leaves. Plant responses in two age groups, which differed in the type of photosynthesis (juvenile plants had C3 type of photosynthesis, whereas adult plants were at the transition stage to Crassulacean Acid Metabolism (CAM) photosynthesis), differed in the levels of constitutive proline and proline, induced by NaCl and paraquat, as well as in activities of superoxide dismutase (SOD) and catalase. Changes in SOD activity and proline accumulation in response to paraquat treatment combined with NaCl revealed opposite dependence to accumulation of proline: the more proline accumulated in leaves, the lower activity of the enzyme. In response to paraquat treatment, the content of chlorophylls a and b most drastically declined in juvenile plants. Negative effect of salinity on the content of chlorophylls was lower than that of paraquat and was almost the same in plants of both age groups. Protective effect of exogenous proline was most profound in the case of paraquat treatment. Exogenous proline decreased the rate of lipid peroxidation, the content of superoxide radical and, consequently, SOD activity (almost fivefold), and increased the content of chlorophylls (a and b) in leaves of adult plants. The obtained data suggest that stress-induced accumulation of proline in the common ice plant has both osmoprotectory and antioxidant functions.

Journal

Russian Journal of Plant PhysiologySpringer Journals

Published: Sep 8, 2009

References

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