Journal Article

Characterization of Oxalate Oxidase and Cell Death in Al-Sensitive and Tolerant Wheat Roots

Georges Delisle, Marie Champoux and Mario Houde

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 42, issue 3, pages 324-333
Published in print March 2001 | ISSN: 0032-0781
Published online March 2001 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pce041
Characterization of Oxalate Oxidase and Cell Death in Al-Sensitive and Tolerant Wheat Roots

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Several genes including oxalate oxidase (Oxo) are up-regulated in Triticum aestivum L. root tips exposed to Al. To better understand the function of Oxo during Al exposure, the protein level and enzyme activity were measured. The data indicate that both Oxo protein and activity are increased proportionally to the level of root growth inhibition (RGI). A high level of Oxo expression may result in excess H2O2 production which could become toxic and induce cell death. However, the timing of H2O2 production (observed after 24 h) indicates that it cannot be the primary cause of cell death first observed after 8 h. Moreover, at Al concentrations resulting in 50% RGI, we did not observe any cell death in the sensitive cultivar while a punctated pattern of death involving small groups of cells was found in the tolerant cultivar. This pattern was maintained for several days in the tolerant cultivar, suggesting the involvement of a cell death mechanism aimed at replacing epidermal cells intoxicated with Al while root growth is maintained. The accelerated epidermal cell turnover may represent a new detoxification mechanism helping to protect deeper cell layers of the meristematic and elongation zone essential for root growth.

Keywords: Key words: Aluminum toxicity — Cell death — Detoxification — H2O2 — Oxalate oxidase — Wheat.; Abbreviations: Oxo, oxalate oxidase; PR, pathogenesis-related; RGI, root growth inhibition.

Journal Article.  7034 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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