Heavy metals and mycorrhizal symbiosis:: Phytoremediation strategies

Anthropogenic sources of heavy metal contamination include industrial manufacturing, energy and fuel production, gas exhaust and also excessive fertilizer use in intensive agricultural practices. Unlike other organic contaminants most metals cannot be eliminated of the environment by chemical or biological transformation making heavy metal polluted soils a major environmental concern and a health hazard. The various conventional remediation technologies that can be used to clean metal polluted soils are complex and expensive processes both from an economic and environmental standpoint. A variety of biological resources, including plants and microorganisms are being considered for the remediation of metal contaminated ecosystems and are emerging as an important area of research in the field of environmental biotechnology. In this context the use of heavy metal tolerant plants is being studied as a system to clean up contaminated soils and to immobilize toxic elements. Mycorrhiza are soil organisms that provide a unique link between the soil system and the plant, and can therefore be of importance in the heavy metal availability and toxicity to plants. Different aspects of these symbioses and their implication in phytoreclamation processes are discussed.