Heavy metals and woody plants - biotechnologies for phytoremediation

Soil contamination by heavy metals is among the most serious danger for the environment, and the new methods for its containment and removal are claimed, in particular for agricultural soils. Phytoremediation is an emerging, potentially effective technology applicable for remediation of contaminated soils and waters. Besides hyperaccumulator herbaceous plants, several woody species are now considered of interest for this purpose. Many woody plants are fast growing, have deep roots, produce high biomass, are easy to harvest, and some of them have shown some capacity to tolerate and accumulate heavy metals. Biotechnologies are now available for investigating this potential and enlarge the possibilities of exploitation of trees for remediation. The use of in vitro cultures, yhe role of bacteria and mychorrhizas, the powerful tool of genetic engineering, are some of the aspects focused in this paper that open prospects of global relevance for a better understanding of the processes related to the uptake of heavy metals by woody plants. In recent years significant progress has been made in identifying native plants and developing genetically modified tree plants for the remediation of heavy-metal polluted environment. Despite the intensive research developed in the last years, few field trials demonstrated the feasibility of the approach described, therefore much efforts should be addressed to this goal.