高等植物金属抗性中有机酸的作用及其机理

植物的金属抗性可通过避性和耐性途径获得。具有螯合能力的有机酸在植物的金属外部排斥(避性)机制和内部耐受(耐性)机制中均具有重要作用。在金属的外部排斥过程中,植物根系分泌有机酸,与金属离子形成稳定的复合体,降低土壤金属的移动性,达到体外解毒的目的。超积累型植物的内部耐受机制主要体现在,有机酸可与金属元素发生螯合作用,将离子态的金属转变成低毒或无毒的螯合态,从而降低细胞内金属离子的毒害效应。有机酸的种类受植物种类、金属类型等因素的影响。

Action and mechanisms of organic acids in higher plants resisting to metals

The resistance of plants to metals includes avoidance and tolerance,while the organic acids with chelating ability in plants play an important role in the detoxification of metals both externally and internally. In the external metal detoxification,plant roots excrete organic acids into rhizosphere,and the metal pollutants are detained outside the roots by the formation of metal-organic acid complex. In the internal metal detoxification,the metal pollutants in cytosol are chelated with the organic acids,and their toxicity is reduced. The formed organic acids in plants are differed with plant species and metal pollutants.