Arbuscular mycorrhizal fungi and heavy metal contaminated soils

Arbuscular mycorrhizal fungi (AMF) associations are integral, functioning parts of plant roots and are widely recognized as enhancing plant growth on severely disturbed sites, including those contaminated with heavy metals (HMs). They are reported to be present on the roots of plants growing on HM-contaminated soils and play an important role in metal tolerance and accumulation. Isolation of the indigenous and presumably stress-adapted AMF can be a potential biotechnological tool for inoculation of plants for successful restoration of degraded ecosystems. Plants grown in metal contaminated sites harbour unique metal tolerant and resistant microbial communities in their rhizosphere. These rhizo-microflora secrete plant growth-promoting substances, siderophores, phytochelators to alleviate metal toxicity, enhance the bioavailability of metals (phytoremediation) and complexation of metals (phytostabilisation). Most studies of HM toxicity to soil microorganisms have concentrated on effect where loss of microbial function can be observed and the effects on biodiversity within microbial populations and communities have not significantly been evaluated. This review highlights the interaction between HM-contaminated soils and AMF.