内外生菌根真菌对重金属的耐受性及机理

本文从内外生菌根真菌对重金属的耐受性和耐受机理,以及将菌根真菌作为重金属污染程度的生物指示剂和重金属生物修复等方面对菌根真菌和重金属的相互作用作了较全面的论述。重金属对生物圈的污染是一个严重的环境和健康问题。某些内外生菌根真菌对重金属具有耐受性。菌根真菌菌丝能与金属相结合而限制它们向菌根植物地上部迁移,从而可达到植物稳定和保护植物免遭重金属毒害的目的。内外生菌根真菌对重金属的耐受性因菌种、重金属种类和浓度、与宿主植物共生与否以及所生长的土壤条件等而异,同时种内菌株之间也有差异。菌根真菌通过离子交换,络合物的形成,沉淀或结晶化作用等方式获得对重金属的耐受性,其子实体内重金属含量,繁殖体密度和侵染势可作为重金属污染程度的生物指示剂。

TOLERANCE OF MYCORRHIZAL FUNGI TO HEAVY METALS AND MECHANISMS

Pollution of the biosphere with heavy metals poses a major environmental and human health problem. Phytoremediation methods (including phytoextraction, rhizofiltration and phytostabilization) have recently attracted much attention. Mycorrhizal infection exists in most heavy-metal-polluted environment, suggesting that heavy metal tolerance or other beneficial effects are conferred by the mycorrhizal symbiosis. Mycorrhizae can bind metals and limit their translocation to shoot, and provide a new way for phytostabilization and protect plants against the toxicity of heavy metals. Ectomycorrhizal and endomycorrhizal fungi can accumulate high metal contents in their fruiting bodies, and that metal accumulation varies between species and strains. Mycorrhizal fungi tolerate the toxicity of heavy metals by ion exchange, formation of complexes, precipitation or crystallization. Heavy metals content in the fruitbodies of mycorrhizal fungi, propagule density and infectivity can be used as bioindicators of soil contamination.