有机酸在植物解铝毒中的作用及生理机制

酸性土壤上铝毒是限制作物产量的一个重要障碍因子。具有螯合能力的有机酸在植物铝的外部排斥机制和内部耐受机制均具有重要作用。在铝的外部排斥解毒过程中，植物通过根系分泌有机酸进入根际，如柠檬酸、草酸、苹果酸等与铝形成稳定的复合体，阻止铝进入共质体，从而达到植物体外解除铝毒害效应的目的，且分泌的有机酸对铝的胁迫诱导表现出高度的专一性，分泌的关键点位于根尖。不同的物种间分泌的有机酸种类、分泌的模式及生理机理存在差异。在铝积累型植物的内部解毒过程中，有机酸与铝形成稳定的化合物，降低植物体内铝离子的生理活性,从而降低细胞内铝离子的毒害效应,如绣球花中铝与柠檬酸形成1:1的复合体，荞麦内铝与草酸形成1:3的复合体。本文就有机酸在植物忍耐和积累铝中的作用及生理机制作一简要综述。

Role of Organic Acid in Detoxification of Aluminum in Higher Plants and Its Mechanisms

Phytotoxicity of aluminum ion (Al3+) is a serious problem limiting crop production in acidic soils. Organic acids with Al_chelating ability play an important role in the detoxification of Al both externally and internally. Aluminum is detoxified externally by the secretion of organic acids such as citric, oxalic, and /or malic acid from the roots. The secretion of organic acids is highly specific to Al and the site of secretion is localized to the root apex. The kinds of organic acids secreted as well as secretion patterns differ among plant species. Internal detoxification of Al_accumulating plants is achieved by the formation of Al_organic acid complex. For instance, the complex of Al_citric（1:1)in hydrangea and Al_oxalate(1:3) in buckwheat has been identified. In the paper the role of organic acid in detoxification of aluminum in higher plants and its mechanisms are reviewed.