United States Salinity Laboratory, Soil and Water Conservation Research Division, Agricultural Research Service, United States Department of Agriculture, Riverside, California 92502.
Plant Physiol. 1971 Mar;47(3):357-60. doi: 10.1104/pp.47.3.357.
Absorption characteristics of Mg(2+) and Cl(-) were investigated with 5-day-old excised corn (Zea mays) roots. Uptake from both 0.5 and 10 milliequivalents per liter MgCl(2) solutions occurred at steady state rates for the first 6 hours. Inhibition by dinitrophenol and low temperatures established that absorption during this period was metabolically mediated in the absence and presence of Ca(2+). Absorption isotherms indicated dual mechanisms of Mg(2+) and Cl(-) absorption from solutions above 1 milliequivalent per liter. The effect of H(+) on absorption of Mg(2+) and Cl(-) was typical of that generally reported for other plant roots and other ions. In the physiological pH range, Ca(2+) greatly suppressed the rate of Mg(2+) absorption but had little effect on Cl(-). The influence of Ca(2+) on Mg(2+) appeared to be noncompetitive and independent of its effect on membrane permeability.
用 5 天龄的离体玉米（Zea mays）根研究了 Mg(2+)和 Cl(-)的吸收特性。从 0.5 和 10 毫当量/升 MgCl(2)溶液中摄取的 Mg(2+)在最初 6 小时内以稳定的速率发生。二硝基苯酚和低温的抑制作用表明，在不存在和存在 Ca(2+)的情况下，这一时期的吸收是代谢介导的。吸收等温线表明，在 1 毫当量/升以上的溶液中，Mg(2+)和 Cl(-)的吸收存在双重机制。H(+)对 Mg(2+)和 Cl(-)吸收的影响与通常报道的其他植物根和其他离子的影响相似。在生理 pH 范围内，Ca(2+)极大地抑制了 Mg(2+)的吸收速率，但对 Cl(-)几乎没有影响。Ca(2+)对 Mg(2+)的影响似乎是非竞争性的，与其对膜通透性的影响无关。
