Arbuscular mycorrhizal fungi: an ecological accelerator of phytoremediation of metal contaminated soils

In recent decades, contamination of soil with toxic metals has become a severe environmental problem. Although phytoremediation has emerged as a promising environment-friendly remediation technology, an exclusively derived process by plants alone is time-consuming and is restricted by their limited metal tolerance and accumulation capacity. As a natural bio-accelerator, arbuscular mycorrhizal fungi (AMF) are considered as a significant component of phytoremediation systems, due to their intrinsic ability to mitigate metal toxicity (bioalleviation), stimulate plant growth (biofertilization) as well as alter the nutrients and heavy metals (HMs) bioavailability in soil ecosystem. In the present review, considerable efforts have been made to elucidate the role of AMF in phytoremediation and the mechanisms used by AMF to change plant metal uptake through various biogeochemical processes, like metal detoxification, metal mobilization or immobilization, accumulation, transformation, and translocation. Moreover, we present a summary of the findings of various studies showing the benefits of AMF for metal phytoremediation.