Abstract
The role of Al interactions with root-cell plasma membrane (PM) Ca2+ channels in Al toxicity and resistance was studied. The experimental approach involved the imposition of a transmembrane electrical potential (via K+ diffusion) in right-side-out PM vesicles derived from roots of two wheat (Triticum aestivum L.) cultivars (Al-sensitive Scout 66 and Al-resistant Atlas 66). We previously used this technique to characterize a voltage-dependent Ca2+ channel in the wheat root PM (J.W. Huang, D.L. Grunes, L.V. Kochian [1994] Proc Natl Acad Sci USA 91: 3473-3477). We found that Al3+ effectively blocked this PM Ca2+ channel; however, Al3+ blocked this Ca2+ channel equally well in both the Al-sensitive and -resistant cultivars. It was found that the differential genotypic sensitivity of this Ca2+ transport system to Al in intact roots versus isolated PM vesicles was due to Al-induced malate exudation localized to the root apex in Al-resistant Atlas but not in Al-sensitive Scout. Because malate can effectively chelate Al3+ in the rhizosphere and exclude it from the root apex, the differential sensitivity of Ca2+ influx to Al in intact roots of Al-resistant versus Al-sensitive wheat cultivars is probably due to the maintenance of lower Al3+ activities in the root apical rhizosphere of the resistant cultivar.
Full Text
The Full Text of this article is available as a PDF (977.1 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bradford M. M. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976 May 7;72:248–254. doi: 10.1016/0003-2697(76)90527-3. [DOI] [PubMed] [Google Scholar]
- Caldwell C. R. Analysis of aluminum and divalent cation binding to wheat root plasma membrane proteins using terbium phosphorescence. Plant Physiol. 1989 Sep;91(1):233–241. doi: 10.1104/pp.91.1.233. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cosgrove D. J., Hedrich R. Stretch-activated chloride, potassium, and calcium channels coexisting in plasma membranes of guard cells of Vicia faba L. Planta. 1991 Dec;186(1):143–153. doi: 10.1007/BF00201510. [DOI] [PubMed] [Google Scholar]
- Delhaize E., Ryan P. R., Randall P. J. Aluminum Tolerance in Wheat (Triticum aestivum L.) (II. Aluminum-Stimulated Excretion of Malic Acid from Root Apices). Plant Physiol. 1993 Nov;103(3):695–702. doi: 10.1104/pp.103.3.695. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ding J. P., Pickard B. G. Mechanosensory calcium-selective cation channels in epidermal cells. Plant J. 1993 Jan;3(1):83–110. [PubMed] [Google Scholar]
- Gelli A., Blumwald E. Calcium Retrieval from Vacuolar Pools (Characterization of a Vacuolar Calcium Channel). Plant Physiol. 1993 Aug;102(4):1139–1146. doi: 10.1104/pp.102.4.1139. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Huang J. W., Grunes D. L., Kochian L. V. Aluminum Effects on Calcium (45Ca2+) Translocation in Aluminum-Tolerant and Aluminum-Sensitive Wheat (Triticum aestivum L.) Cultivars (Differential Responses of the Root Apex versus Mature Root Regions). Plant Physiol. 1993 May;102(1):85–93. doi: 10.1104/pp.102.1.85. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Huang J. W., Grunes D. L., Kochian L. V. Voltage-dependent Ca2+ influx into right-side-out plasma membrane vesicles isolated from wheat roots: characterization of a putative Ca2+ channel. Proc Natl Acad Sci U S A. 1994 Apr 12;91(8):3473–3477. doi: 10.1073/pnas.91.8.3473. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Huang J. W., Shaff J. E., Grunes D. L., Kochian L. V. Aluminum effects on calcium fluxes at the root apex of aluminum-tolerant and aluminum-sensitive wheat cultivars. Plant Physiol. 1992 Jan;98(1):230–237. doi: 10.1104/pp.98.1.230. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kinraide T. B., Ryan P. R., Kochian L. V. Interactive effects of Al, h, and other cations on root elongation considered in terms of cell-surface electrical potential. Plant Physiol. 1992 Aug;99(4):1461–1468. doi: 10.1104/pp.99.4.1461. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Poovaiah B. W., Reddy A. S. Calcium messenger system in plants. CRC Crit Rev Plant Sci. 1987;6(1):47–103. doi: 10.1080/07352688709382247. [DOI] [PubMed] [Google Scholar]
- Shi B., Haug A. Aluminium interferes with signal transduction in neuroblastoma cells. Pharmacol Toxicol. 1992 Oct;71(4):308–313. doi: 10.1111/j.1600-0773.1992.tb00990.x. [DOI] [PubMed] [Google Scholar]
- Thuleau P., Graziana A., Ranjeva R., Schroeder J. I. Solubilized proteins from carrot (Daucus carota L.) membranes bind calcium channel blockers and form calcium-permeable ion channels. Proc Natl Acad Sci U S A. 1993 Jan 15;90(2):765–769. doi: 10.1073/pnas.90.2.765. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thuleau P., Ward J. M., Ranjeva R., Schroeder J. I. Voltage-dependent calcium-permeable channels in the plasma membrane of a higher plant cell. EMBO J. 1994 Jul 1;13(13):2970–2975. doi: 10.1002/j.1460-2075.1994.tb06595.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Williamson R. E., Ashley C. C. Free Ca2+ and cytoplasmic streaming in the alga Chara. Nature. 1982 Apr 15;296(5858):647–650. doi: 10.1038/296647a0. [DOI] [PubMed] [Google Scholar]
