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https://hdl.handle.net/2440/34565
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Type: | Journal article |
Title: | Malate-permeable channels and cation channels activated by aluminum in the apical cells of wheat roots |
Author: | Zhang, W. Ryan, P. Tyerman, S. |
Citation: | Plant Physiology, 2001; 125(3):1459-1472 |
Publisher: | Amer Soc Plant Physiologists |
Issue Date: | 2001 |
ISSN: | 0032-0889 1532-2548 |
Statement of Responsibility: | Wen-Hao Zhang, Peter R. Ryan, and Stephen D. Tyerman |
Abstract: | Aluminum (Al³⁺)-dependent efflux of malate from root apices is a mechanism for Al³⁺ tolerance in wheat (Triticum aestivum). The malate anions protect the sensitive root tips by chelating the toxic Al³⁺ cations in the rhizosphere to form non-toxic complexes. Activation of malate-permeable channels in the plasma membrane could be critical in regulating this malate efflux. We examined this by investigating Al³⁺-activated channels in protoplasts from root apices of near-isogenic wheat differing in Al³⁺ tolerance at a single locus. Using whole-cell patch clamp we found that Al³⁺ stimulated an electrical current carried by anion efflux across the plasma membrane in the Al³⁺-tolerant (ET8) and Al³⁺-sensitive (ES8) genotypes. This current occurred more frequently, had a greater current density, and remained active for longer in ET8 protoplasts than for ES8 protoplasts. The Al³⁺-activated current exhibited higher permeability to malate²⁻ than to Cl⁻ (Pmal/PCl ≥ 2.6) and was inhibited by anion channel antagonists, niflumate and diphenylamine-2-carboxylic acid. In ET8, but not ES8, protoplasts an outward-rectifying K⁺ current was activated in the presence of Al³⁺ when cAMP was included in the pipette solution. These findings provide evidence that the difference in Al³⁺-induced malate efflux between Al³⁺-tolerant and Al³⁺-sensitive genotypes lies in the differing capacity for Al³⁺ to activate malate permeable channels and cation channels for sustained malate release. |
Keywords: | Triticum Plant Roots Aluminum Malates Niflumic Acid Ion Channels Cyclic AMP Biological Transport Permeability ortho-Aminobenzoates |
DOI: | 10.1104/pp.125.3.1459 |
Published version: | http://www.plantphysiol.org/cgi/content/abstract/125/3/1459 |
Appears in Collections: | Agriculture, Food and Wine publications Aurora harvest 6 |
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