Aromatic and medicinal plants for phytoremediation: A sustainable approach

Abstract

Soil and water contamination with heavy metal and organic pollutants has become a worldwide environmental health issue that has attracted considerable public attention. Heavy metal pollution poses a great threat to the health and well-being of human and other organisms due to accumulation through the food chain. One of the greenest and sustainable approaches for reclamation of heavy metal contaminated sites is by phytoremediation with aromatic and medicinal plants. Cultivation of aromatic and medicinal plants instead of edible food plants in polluted areas has been proposed by a number of researchers as it fulfils the purpose of remediation alongside monetary benefits. In this chapter, research done on remediation by aromatic and medicinal plants and major scientific progress in understanding the physiological mechanism of this process has been described. In this context, the knowledge on the applicability of aromatic and medicinal plants for remediation has been gathered to date from both in vitro studies and field trials using real environmental conditions. Plants adopted for phytoremediation are reported to have this specific property due to the presence of the special genes coding for it. These specific genes are isolated and expressed in wide variety of transgenic plants so that they can be made resistant as well. Certain plants are reported to show increased resistance under the presence of certain microbes. Biotechnology makes it possible to isolate such microbes and enrich the soil so as to enhance the phytoremediation by respective plants. To increase the number of plant species for phytoremediation, chloroplast engineering allows for the transfer of bacterial operons into transgenic plants for high expression of enzymes involved in phytoremediation. This chapter also reviews the biotechnological approaches to improve phytoremediation efficiency of aromatic and medicinal plants and highlights future challenges. We recommend that more research should be performed on the selection of potential aromatic and medicinal plant taxa for various sets of environmental conditions and for economic aspects.