Aluminum effects on calcium fluxes at the root apex of aluminum-tolerant and aluminum-sensitive wheat cultivars |
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| Authors: | Huang J W Shaff J E Grunes D L Kochian L V |
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| Affiliation: | Department of Soil, Crop and Atmospheric Sciences, Cornell University, Ithaca, New York 14853. |
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| Abstract: | The role of Ca2+ transport in the mechanism of Al toxicity was investigated, using a Ca2+-selective microelectrode system to study Al effects on root apical Ca2+ fluxes in two wheat (Triticum aestivum L.) cultivars: Al-tolerant Atlas 66 and Al-sensitive Scout 66. Intact 3-day-old low-salt-grown (100 micromolar CaCl2, pH 4.5) wheat seedlings were used, and it was found that both cultivars maintained similar rates of net Ca2+ uptake in the absence of Al. Addition of Al concentrations that were toxic to Scout (5-20 micromolar AlCl3) immediately and dramatically inhibited Ca2+ uptake in Scout, whereas Ca2+ transport in Atlas was relatively unaffected. The Al-induced inhibition of Ca2+ uptake in Scout 66 was rapidly reversed following removal of Al from the solution bathing the roots. Similar studies with morphologically intact root cell wall preparations indicated that the Al effects did not involve Al-Ca interactions in the cell wall. These results suggest that Al inhibits Ca2+ influx across the root plasmalemma, possibly via blockage of calcium channels. The differential effect of Al on Ca2+ transport in Al-sensitive Scout and Al-tolerant Atlas suggests that Al blockage of Ca2+ channels could play a role in the cellular mechanism of Al toxicity in higher plants. |
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