Malate-permeable channels and cation channels activated by aluminum in the apical cells of wheat roots

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dc.contributor.authorZhang, W.
dc.contributor.authorRyan, P.
dc.contributor.authorTyerman, S.
dc.date.issued2001
dc.description.abstractAluminum (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.
dc.description.statementofresponsibilityWen-Hao Zhang, Peter R. Ryan, and Stephen D. Tyerman
dc.identifier.citationPlant Physiology, 2001; 125(3):1459-1472
dc.identifier.doi10.1104/pp.125.3.1459
dc.identifier.issn0032-0889
dc.identifier.issn1532-2548
dc.identifier.orcidTyerman, S. [0000-0003-2455-1643]
dc.identifier.urihttp://hdl.handle.net/2440/34565
dc.language.isoen
dc.publisherAmer Soc Plant Physiologists
dc.source.urihttp://www.plantphysiol.org/cgi/content/abstract/125/3/1459
dc.subjectTriticum
dc.subjectPlant Roots
dc.subjectAluminum
dc.subjectMalates
dc.subjectNiflumic Acid
dc.subjectIon Channels
dc.subjectCyclic AMP
dc.subjectBiological Transport
dc.subjectPermeability
dc.subjectortho-Aminobenzoates
dc.titleMalate-permeable channels and cation channels activated by aluminum in the apical cells of wheat roots
dc.typeJournal article
pubs.publication-statusPublished

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