Appalachian Soil and Water Conservation Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beckley, West Virginia 25802-0867.
Plant Physiol. 1992 Aug;99(4):1461-8. doi: 10.1104/pp.99.4.1461.
The rhizotoxicities of Al(3+) and of La(3+) to wheat (Triticum aestivum L.) were similarly ameliorated by cations in the following order of effectiveness: H(+) approximately C(3+) > C(2+) > C(1+). Among tested cations of a given charge, ameliorative effectiveness was similar except that Ca(2+) was slightly more effective than other divalent cations and H(+) was much more effective than other monovalent cations. H(+) rhizotoxicity was also ameliorated by cations in the order C(3+) > C(2+) > C(1+). These results suggest a role for cell-surface electrical potential in the rhizotoxicity of Al(3+), La(3+), H(+), and other toxic cations: negatively charged cell surfaces of the root accumulate the toxic cations, and amelioration is effected by treatments that reduce the negativity of the cell-surface electrical potential by charge screening or cation binding. Membrane-surface activities of free Al(3+) or La(3+) computed according to a Gouy-Chapman-Stern model correlated well with growth inhibition, which correlated only poorly with Al(3+) or La(3+) activities in the external medium. The similar responses of Al-intoxicated and La-intoxicated roots to ameliorative treatments provide evidence that Al(3+), rather than AlOH(2+) or Al(OH)(2) (+), is the principal toxic species of mononuclear Al. Comparisons of the responses of Al-sensitive and Al-tolerant wheats to Al(3+) and to La(3+) did not support the hypothesis that varietal sensitivity to Al(3+) is based upon differences in cell-surface electrical potential.
Al(3+) 和 La(3+) 对小麦（Triticum aestivum L.）的根毒性受到以下阳离子的有效性的类似缓解：H(+) 近似于 C(3+) > C(2+) > C(1+)。在所测试的具有相同电荷的阳离子中，除了 Ca(2+) 比其他二价阳离子略有效，而 H(+) 比其他一价阳离子更有效外，缓解效果相似。H(+) 的根毒性也按照 C(3+) > C(2+) > C(1+)的顺序被阳离子缓解。这些结果表明，细胞表面电势能在 Al(3+)、La(3+)、H(+)和其他毒性阳离子的根毒性中起作用：带负电荷的根表面积累毒性阳离子，通过电荷屏蔽或阳离子结合来降低细胞表面电势能的处理可以缓解毒性。根据 Gouy-Chapman-Stern 模型计算的游离 Al(3+)或 La(3+)的膜表面活性与生长抑制密切相关，而与外部介质中 Al(3+)或 La(3+)的活性相关性较差。受 Al 毒害和 La 毒害的根对缓解处理的类似反应提供了证据，表明 Al(3+)而不是 AlOH(2+)或 Al(OH)(2)+是单核 Al 的主要毒性物种。对 Al 敏感和 Al 耐受小麦对 Al(3+)和 La(3+)的反应的比较并不支持 Al(3+)敏感性基于细胞表面电势能差异的假说。
