Toxins and their phytoremediation

The agricultural and industrial revolutions in the last few decades have resulted in increased concentration of toxins in our environment that are now-a-days a major cause of toxicity in plants and animals. Among different toxins, increasing levels of salts, heavy metal, pesticides and other chemicals are posing a threat to agricultural as well as natural ecosystems of the world. These contaminants result in soil, air and water pollution, and loss of arable lands as well as crop productivity. They also cause changes in species composition and loss of biodiversity by bringing about changes in the structure of natural communities and ecosystems. In this situation, different approaches are being adopted to reclaim polluted environments. Among these, phytoremediation has a potential in removing these toxins from the environment. This approach is based on the use of natural hyperaccumulator plant species that can tolerate relatively high levels of pollutants in the environment. Pollutants accumulated in stems and leaves of high biomass producing and tolerant plants can be harvested and removed from the site. Therefore, this approach has a potential to remove large amounts of toxins by harvesting the above-ground biomass. However, the effectiveness of phytoremediation approach can be increased if we have better knowledge of physiological, biochemical, molecular and genetic bases of plant resistance to natural and anthropogenic induced toxins. All these aspects of toxicity mechanisms and their removal techniques are comprehensively reviewed in this book. © Springer Science+Business Media B.V. 2010

Assessment of successful experiments and limitations of phytotechnologies : contaminant uptake, detoxification and sequestration, and consequences for food safety

PURPOSE: The term "phytotechnologies" refers to the application of science and engineering to provide solutions involving plants, including phytoremediation options using plants and associated microbes to remediate environmental compartments contaminated by trace elements (TE) and organic xenobiotics (OX). An extended knowledge of the uptake, translocation, storage, and detoxification mechanisms in plants, of the interactions with microorganisms, and of the use of "omic" technologies (functional genomics, proteomics, and metabolomics), combined with genetic analysis and plant improvement, is essential to understand the fate of contaminants in plants and food, nonfood and technical crops. The integration of physicochemical and biological understanding allows the optimization of these properties of plants, making phytotechnologies more economically and socially attractive, decreasing the level and transfer of contaminants along the food chain and augmenting the content of essential minerals in food crops. This review will disseminate experience gained between 2004 and 2009 by three working groups of COST Action 859 on the uptake, detoxification, and sequestration of pollutants by plants and consequences for food safety. Gaps between scientific approaches and lack of understanding are examined to suggest further research and to clarify the current state-of-the-art for potential end-users of such green options. CONCLUSION AND PERSPECTIVES: Phytotechnologies potentially offer efficient and environmentally friendly solutions for cleanup of contaminated soil and water, improvement of food safety, carbon sequestration, and development of renewable energy sources, all of which contribute to sustainable land use management. Information has been gained at more realistic exposure levels mainly on Cd, Zn, Ni, As, polycyclic aromatic hydrocarbons, and herbicides with less on other contaminants. A main goal is a better understanding, at the physiological, biochemical, and molecular levels, of mechanisms and their regulation related to uptake-exclusion, apoplastic barriers, xylem loading, efflux-influx of contaminants, root-to-shoot transfer, concentration and chemical speciation in xylem/phloem, storage, detoxification, and stress tolerance for plants and associated microbes exposed to contaminants (TE and OX). All remain insufficiently understood especially in the case of multiple-element and mixed-mode pollution. Research must extend from model species to plants of economic importance and include interactions between plants and microorganisms. It remains a major challenge to create, develop, and scale up phytotechnologies to market level and to successfully deploy these to ameliorate the environment and human healt