Phytoremediation is a new, promising, quickly developing technique for environmental clean-up. Some plants have the ability to accumulate contaminants by building them into the structure of their own cells, others can collect and metabolize toxins as a result of the natural process of adaptation to difficult life conditions in contaminated environment. The idea of introducing plant systems for environmental cleaning has many advantages, including significantly lower remediation costs compared to traditional methods, convenience of use, favourable effect on soil, and stimulation of the growth of microbial populations. Additionally, the technology is friendly to the environment and improves its aesthetic features.
In order to increase remediation potential of the plants used for recultivation of contaminated environment, attempts are being made to increase their tolerance, accumulation and degradation of particular pollutants. The plants are modified by conventional methods of reproduction, hybridization, formation of interspecies hybrids, as well as by genetic modification. Owing to the introduction of foreign genes, the produced plants show increased or decreased activity of the desired metabolic pathways, higher biomass and growth, and increased activity of the enzymes limiting phytoremediation of particular xenobiotics or the presence of relatively new biochemical properties. The paper discusses the latest results of plant modification at the level of natural metabolic pathways, transgenic plants with new properties, genetic modifications of endophytes and application of immunonodulation that increases protection against xenobiotics
Extensive industrial and agricultural development of the 20th century is one of the causes of wide-spread contamination of the environment by organic pollutants such as polyaromatic hydrocarbons, pesticides and explosive compounds. Nowadays, apart from traditional remediation techniques involving mechanical treatment, we are facing new opportunities of utilizing microorganisms (bioremediation) and plants (phytoremediation) to contain, transform or remove toxic elements present in soils, water and, to some point, in atmosphere. Great diversity of living organisms and application of genetic engineering make bio- and phytoremediation even more attractive.
The influence of a xenobiotic, a substrate and elicitors on glutathione S-transferase, peroxidase activities and glutathione concentration was studied in reed cannarygrass. The induction of both enzymes? activities and glutathione concentrations by 4-chlorophenol (xenobiotic), benzyl isothiocyanate (substrate), salicylic acid and 3-aminobutyric acid (substrate) was shown. Salicylic acid treatment increased glutathione level, but did not decrease GSH/GSSG ratio. The ability of reed cannarygrass to adsorb 4-chlorophenol in the hydroponic culture was demonstrated. The obtained results suggest that the reed cannarygrass has significant potential to conjugate xenobiotics with glutathione and it may be useful for phytoremediation.
Phytoremediation is a field of science and technology that uses plants to clean up polluted soil and water. Metal hyperaccumulator plants are naturally capable of accumulating trace elements, primarily Ni, Zn, Cd, As or Se in their above-ground tissues, without developing any toxicity symptoms. Although these plants appear to have ideal properties for phytoextraction, most of them produce little biomass and grow only in ecosystems that are characteristic for them. The introduction of novel traits into high biomass plants using a transgenic approach is a promising strategy for the development of effective phytoremediation technologies. A number of transgenic plants have been generated in an attempt to modify: (a) trace element uptake from environment, (b) transport to organelles, (c) allocation within the plants, (d) synthesis of metal complexing ligands present in the cell or exported to the apoplast and/or environment, (e) metabolism of the metal containing a compound. Many experimental results demonstrate that a single-gene plant transformation rarely leads to intended phenotypes. In this paper, we present some selected results dealing with suitability of genetically modified plants for phytoremediation.
Heavy metals have been increasing in the environment as a result of either natural processes or human industrial activities. Many of the heavy metals affect and damage various developmental and biochemical processes causing reduction in growth, inhibition of photosynthesis and respiration and degeneration of main cell organelles. It is mostly due to the promoting effect of heavy metals on the formation of harmful reactive oxygen species (ROS) which disturb the whole cellular machinery. There is a requirement for a balance between the uptake of essential metal ions and the ability of plants to protect sensitive cellular structures and activities from excessive level of metals. The resistance of plants to heavy metals depends on the reduction of uptake and translocation from the root to the shoot, binding by appropriate ligands and, finally, transferring to the vacuole. The phytotoxic effect of heavy metals is effectively counteracted by the metal-binding proteins and peptides like metalothioneins, chaperones and phytochelatins as well as some organic acids. Another very important aspect of the heavy metal detoxication is the presence of an efficient ROS scavenging system consisting of low molecular antioxidants and antioxidant enzymes. Some plants can hyperaccumulate metal ions that are toxic for other species. Such plants can serve as donors of traits that could be used to clean up the environment. Several methods can be applied to create plants able to remove the xenobiotics from the environment: sexual or somatic hybridization, mutagenesis, in vitro selection of metal-resistant cell lines and engineering of metal-accumulating transgenic plants. The use of specially selected and engineered metal-accumulating plants for environmental clean-up is a novel technology called phytoremediation. This rapidly emerging biotechnology consists of some branches suitable to toxic metals remediation: 1) phytoextraction ? the use of plants to remove heavy metals from the soil, 2) phytostabilization ? the use of plants to complex and eliminate the availability of toxic metals in soils, 3) rhizofiltration ? the use of plant roots to remove heavy metals from polluted waters. Some new approaches concerning the use of transgenic plants as sensitive bioindicators of toxic heavy metals and soils contaminated with radionuclides are presented.
This review summarises the mechanisms of heavy metal tolerance in plants. Plants have many endogenous genetic, biochemical, and physiological properties that make them ideal agents for soil and water remediation. Phytoremediation is widely viewed as an ecological alternative to the environmentally destructive physical remediation methods currently in use.
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.