Abstract Many studies ask how aluminum (Al) reduces the root growth, but as Al is mostly retained in the root system, physiological explanations for the also expected Al-induced decrease in stomatal conductance (gs) are unclear, mainly in well-watered conditions. We exposed tomato plants (Solanum lycopersicum) to 0, 25, 50 and 100 μM Al in nutrient solution to investigate whether Al impairs root hydraulic conductance (Lpr), affecting leaf water potential (Ψleaf) and possibly inducing abscisic acid (ABA) accumulation in roots and/or leaves. We also measured ABA delivery rate, xylem sap pH and the root/leaf area ratio in order to explain the low gs in plants exposed to Al. Declines in Lpr and gs were proportional to the increase in Al concentration, and all Al treatments similarly decreased Ψleaf, indicating the plant’s attempt to reduce water loss through transpiration while accumulating more ABA. Despite Al-induced increases in root ABA, the root-to-shoot delivery of ABA did not enhance, but Al caused root xylem sap alkalization. Despite the stability of root/leaf area ratio across a range of Al concentrations (0, 25 and 50 μM Al), the leaf hydration and stomatal opening was not conserved. Here we provide the first evidence that decreases in Lpr and increases in ABA might explain Al-induced stomatal closure.

中文翻译：

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铝诱导气孔关闭与低根系水力导度和高 ABA 积累有关

摘要 许多研究询问铝 (Al) 如何减少根系生长，但由于铝主要保留在根系中，因此铝引起的气孔导度 (gs) 降低的生理学解释尚不清楚，主要是在浇水充足的条件下. 我们将番茄植株 (Solanum lycopersicum) 暴露于营养液中的 0、25、50 和 100 μM 铝中，以研究铝是否会损害根部水力传导率 (Lpr)、影响叶水势 (Ψleaf) 并可能诱导脱落酸 (ABA) 在根和/或叶。我们还测量了 ABA 传递率、木质部汁液 pH 值和根/叶面积比，以解释暴露于铝的植物的低 gs。Lpr 和 gs 的下降与 Al 浓度的增加成正比，所有 Al 处理类似地降低了 Ψleaf，表明植物试图通过蒸腾作用减少水分流失，同时积累更多的 ABA。尽管铝诱导了根 ABA 的增加，但根到地上部的 ABA 传递并未增强，但铝导致根木质部汁液碱化。尽管根/叶面积比在一系列铝浓度（0、25 和 50 μM 铝）中保持稳定，但叶水合作用和气孔开放不守恒。在这里，我们提供了第一个证据，即 Lpr 的减少和 ABA 的增加可能解释了铝诱导的气孔关闭。叶片水合作用和气孔开放不守恒。在这里，我们提供了第一个证据，即 Lpr 的减少和 ABA 的增加可能解释了铝诱导的气孔关闭。叶片水合作用和气孔开放不守恒。在这里，我们提供了第一个证据，即 Lpr 的减少和 ABA 的增加可能解释了铝诱导的气孔关闭。