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Seasonal Patterns of Glutathione and Ascorbate Metabolism in Field‐Grown Cotton under Water Stress
Author(s) -
Mahan James R.,
Wanjura Don F.
Publication year - 2005
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci2005.0193
Subject(s) - glutathione reductase , malondialdehyde , antioxidant , glutathione , oxidative stress , metabolism , glutathione peroxidase , biochemistry , biology , peroxidase , chemistry , catalase , enzyme
The goal of this study was to identify water‐stress‐related limitations in the antioxidant protection in cotton ( Gossypium hirsutum L.) in the field. Cotton was grown under full irrigation and severe‐to‐moderate water deficits in both years of the study. The amount and form of glutathione (5‐L‐glutamyl‐L‐cysteinylglycine) were monitored in both years, while the antioxidant enzymes ascorbate peroxidase and glutathione reductase, the amount of ascorbate, and the amount of malondialdehyde (MDA) were monitored in the second year of the study. The amount of glutathione varied (> 2×) during the sampling interval, though there was no effect of water treatment on the variation. The ratio of reduced/oxidized glutathione varied seasonally, but not in response to water deficits. Gluthione reductase activity varied (≈ 5×) seasonally, but again not in response to water deficits. The amount of ascorbate and the activity of ascorbate peroxidase were increased under water stress (≈ 5× and 1.5×, respectively). The amount of MDA (an indicator of oxidative damage) varied seasonally (≈ 2×), though not in response to water stress. While glutathione metabolism appears sufficient for oxidative stresses resulting from field‐water deficits, altered ascorbate metabolism may be a response to water deficits in the field. Malondialdehyde amount did not increase with water stress, suggesting that antioxidant metabolism was sufficient for the oxidative stresses. It is apparent that antioxidant metabolism in these plants exposed to water deficits under production conditions was sufficient to protect against oxidative damage.