Aluminum interactions with voltage-dependent calcium transport in plasma membrane vesicles isolated from roots of aluminum-sensitive and -resistant wheat cultivars

• Published in: Plant physiology (Bethesda) 1996-02, Vol.110 (2), p.561-569
• Main Authors: Huang, J.W. (DuPont Central Research and Development, Newark, DE.), Pellet, D.M, Papernik, L.A, Kochian, L.V
• Format: Article
• Language: English
• Subjects: ACIDE MALIQUE; ACIDO MALICO; Agronomy. Soil science and plant productions; ALUMINIO; ALUMINIUM; Aluminum; Biological and medical sciences; CALCIO; CALCIUM; Cell membranes; Cell physiology; CHELATEUR; Economic plant physiology; ESTRUCTURA CELULAR; Exudation; FITOTOXICIDAD; Fundamental and applied biological sciences. Psychology; Guard cells; ION; IONES; Mineral nutrition; Nutrition. Photosynthesis. Respiration. Metabolism; PHYTOTOXICITE; Plant cells; Plant physiology and development; Plant roots; Plants; Plasma membrane and permeation; POTENCIAL ELECTRICO; POTENTIEL ELECTRIQUE; QUELATOS; RACINE; RAICES; STRUCTURE CELLULAIRE; TRITICUM AESTIVUM; VARIACION GENETICA; VARIATION GENETIQUE; VARIEDADES; VARIETE; Wheat; Whole Plant, Environmental, and Stress Physiology
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.110.2.561

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