title: Aluminum-induced oxidative stress and changes in antioxidant defenses in the roots of rice varieties differing in Al tolerance.
abstract: The effects of aluminum (Al) on root elongation, lipid peroxidation, hydrogen peroxide (H(2)O(2)) accumulation, antioxidant levels, antioxidant enzymatic activity, and lignin content in the roots of the Al-tolerant rice variety azucena and the Al-sensitive variety IR64 were investigated. Treatment with Al induced a greater decrease in root elongation and a greater increase in H(2)O(2) and lipid peroxidation as determined by the total thiobarbituric acid-reactive substance (TBARS) level in IR64 than in azucena. Azucena had significantly higher levels of superoxide dismutase, ascorbate peroxidase, glutathione reductase, and glutathione peroxidase GSH POD activity compared with IR64. The concentrations of reduced glutathione (GSH) and ascorbic acid, and the GSH/GSSG ratio (reduced vs. oxidized glutathione) were also higher in azucena than in IR64 in the presence of Al. The addition of 1 mg/L GSH improved root elongation in both varieties and decreased H(2)O(2) production under Al stress. By contrast, treatment with buthionine sulfoximine, a specific inhibitor of GSH synthesis, decreased root elongation in azucena and stimulated H(2)O(2) production in both varieties. Moreover, Al treatment significantly increased the cytoplasmic activity of peroxidase (POD) as well as the levels of POD bound ionically and covalently to cell walls in the Al-sensitive variety. The lignin content was also increased. Treatment with exogenous H(2)O(2) also increased the lignin content and decreased root elongation in IR64. These results suggest that Al induces lignification in the roots of Al-sensitive rice varieties, probably through an increase in H(2)O(2) accumulation.
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Baohui
authors.initials: B
authors.lastname: Ma
authors.forename: Lu
authors.initials: L
authors.lastname: Gao
authors.forename: Hongxiao
authors.initials: H
authors.lastname: Zhang
authors.forename: Jin
authors.initials: J
authors.lastname: Cui
authors.forename: Zhenguo
authors.initials: Z
authors.lastname: Shen
mesh_terms: D000535:Aluminum / Q000494:pharmacology / Q000633:toxicity*; D000975:Antioxidants / Q000032:analysis / Q000378:metabolism*; D060387:Ascorbate Peroxidases / Q000187:drug effects / Q000378:metabolism; D001205:Ascorbic Acid / Q000032:analysis / Q000378:metabolism; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002374:Catalase / Q000187:drug effects / Q000378:metabolism; D005978:Glutathione / Q000187:drug effects / Q000378:metabolism; D005980:Glutathione Reductase / Q000187:drug effects / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000032:analysis / Q000378:metabolism*; D008031:Lignin / Q000032:analysis / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D012275:Oryza / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development / Q000502:physiology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D013482:Superoxide Dismutase / Q000187:drug effects / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis / Q000378:metabolism
chemical_list: D000975:Antioxidants; D017392:Thiobarbituric Acid Reactive Substances; D019328:Buthionine Sulfoximine; D008031:Lignin; D006861:Hydrogen Peroxide; D000535:Aluminum; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D005978:Glutathione; D001205:Ascorbic Acid
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