Phytoremediation of Heavy Metals: An Overview and New Insight on Green Approaches

Abstract

Phytoremediation is a cost-effective, eco-friendly green technology exploiting plants with their natural uptake capabilities through root organization, along with the translocation, bioaggregation or detoxifying abilities to decontaminate the soil, water and groundwater from toxic pollutants. The plant approaches to cope with several xenobiotics include phytostabilization, phytoextraction, phytovolatilization, rhizofiltration, phytodegradation and phytostimulation. Some plants can survive under severe metal stress, and higher metal tolerance can be achieved either by reduced uptake or improved plant internal sequestration of metals, an outcome of interaction between specific plant genotype and its environment. Molecular genetics have led to better understanding of mechanisms of heavy metal tolerance or accumulation in plants, and genetic engineering has unlocked new gateways in phytoremediation strategies by producing elite plants with enhanced metal remediation capabilities. This article reviews the recent developments in phytoremediation of heavy metals addressing the genetic basis of metal hyperaccumulation and tolerance and a discussion on the likelihood of transgenic plants in phytoremediation of heavy metals.