Acc Deaminase And The Reduction Of Plant Ethylene

In higher plants, ethylene is produced from L-methionine via the intermediates, S-adenosyl-L-methionine (SAM) and 1-aminocyclopropane-1-carboxylic acid (ACC) 12 . The enzymes involved in this metabolic sequence are SAM synthetase, which catalyzes the conversion of methionine to SAM 13 ACC synthase, which is responsible for the hydrolysis of SAM to ACC and 5-methylthioadenosine 14 and ACC oxidase, which metabolizes ACC to ethylene, carbon dioxide and cyanide 15 . In 1978, an enzyme capable of...

Anaerobic Dechlorination

The observation that PCB contaminated sediments display a higher content of low chlorinated congeners than the mixture at the origin of the contamination was the first clue that anaerobic bacteria are able to degrade PCBs by a reductive dechlorination process. This process has been well documented for several aquatic sediments 30, 31, 32 . Anaerobic enrichment cultures able to dechlorinate PCBs were maintained in laboratory conditions, with and without sediment 33, 34, 35, 36, 37 . The...

Containing Gene Flow

Several molecular mechanisms have been suggested for containing gene flow (i.e., to prevent gene flow between the phytoremediating species and relatives), especially by pollen, ignoring the other routes of sporophyte propagule (seeds and asexual parts) movement, especially transgenes within the phytoremediating species (i.e., to prevent outflow to related species), or to mitigate the effects of transgene flow once it has occurred 20, 22, 26, 29 . It is more important to prevent gene flow from...

Decision Trees For Assessing The Level Of Risk

Here we combine the different factors through the use of decision trees. We want to state clearly that a decision tree is not a quantitative tool producing a quantified risk. It is an aid in risk evaluation providing unbiased guidance in indicating hazards attached to a certain species. When a hazard is indicated, more detailed and quantified data acquisition will often be necessary. Different levels of certainty apply to the various factors used. For instance invasiveness is highly...

Field scale contaminant fate and hydraulic control

Full-scale phytoremediation of VOCs has been active at contaminated sites since 1995 and 1996. In the decade since then, findings at the field sites have varied. In part the results are sketchy as some processes that are important were not previously considered and data collection is limited and largely unpublished. The full-scale phytoremediation site at the APG J-field site in Maryland is among the best characterized and analysed. Sampling at the site provided some of the first clear...

Forensic Field Studies

While conventional wisdom may dictate a progression from bench to greenhouse to field-testing of remedial technologies, there are distinct advantages to starting directly in the field to examine the rhizoremediation capabilities of natural vegetation. This approach affords a view of the long-term impacts of a diverse array of plant species, including mature trees, on microbial communities and or contaminant disappearance otherwise inaccessible due to the practical time limitations of most...

Info

In vitro culture and micropropagation Developing cell culture and micropropagation protocols for a diverse group of wetland monocot species was facilitated by the availability of a universal cell culture initiation medium, which had successfully been used for a great number of species 8, 10, 15 . The method comprised using immature inflorescences as explants and cultivating the tissue on a primary medium to produce totipotent embryogenic tissue culture, cultivating the embryogenic tissue on a...

KM

Alternatively, empirical relations exist. The TSCF is related to the KOW 11 by a bell-shaped (Gaussian) curve For poplar trees, a similar relation was found by 12 (corrected by authors) It is recommended to use Briggs' equation (4b) 11 for herbal plants and the green vegetables model (experiments were done with the grass barley), and Burken & Schnoors equation (4c) 12 for woody plants and the fruit tree model (experiments were done on poplars). The calculated TSCF (4a) is equivalent to the...

Materials And Methods

Immature inflorescences of Poaceae and Typhaceae were harvested while unemerged and still covered by leaf sheaths. For Cyperaceae and Juncaceae, inflorescences were gathered while the flowers were small early in their development. The explants were surface sterilized by dilute bleach solution then cultured on primary explant medium DM-8 in the dark at 26-28oC. DM-8 medium 10 contained (in mg l-1, unless indicated otherwise) Murashige and Skoog (MS) salts 11 , Sigma Fine Chemicals) 4,300...

Metabolism And Genetic Engineering Studies For Herbicide Phytoremediation

SCHNOOR2 biochemistry and Cell Biology, Rice University, Houston, Texas, USA 2Civil and Environmental Engineering, University of Iowa, Iowa City, IA, 52242, USA - Fax 01 319 3355660 E-mail jerald-schnoor uiowa.edu Herbicides are extensively used for the purpose of crop cultivation and still remain as an important strategy for the commercial agriculture. However, the widespread use of herbicides has resulted in both point source and non-point source...

Mineralization

Factors affecting the formation of metabolites and mineralization of pesticides in soil, plant and rhizosphere. Widespread and large-scale use of pesticides during the last decades has led to a global problem of pollution of soils and water resources. Heavy environmental contamination by pesticides may arise from industrial point sources such as accidental spillage during production, wastewater from pesticide production plants, leakage from old stockpiles, storage and transport of...

Molecular Ecological Methods

Molecular microbial ecology methods bypass culture-bias to provide direct measures of a variety of microbial community parameters. This section highlights some methods that are of particular value to bioremediation studies because of their ability to directly detect the presence, activity, diversity and abundance of degradative organisms. 4.2.1 DNA and RNA extraction methods Many molecular ecological analyses require bacterial DNA and or RNA to be extracted from soil. Depending on both the soil...

Planted Studies

Rhizoremediation experiments conducted by planting and monitoring microbial populations and or contaminant levels over time are powerful approaches since they can be constructed and operated with replication, randomisation and controlled conditions. Perhaps the major limitation of planted studies is time, since for reasons of practicality planted studies are typically only run for 1-3 years. Because roots are estimated to occupy less than 1 of soil 16 , it is reasonable to anticipate that many...

Removal Of Pollutants Via Plants

Phytoextraction refers to the removal of pollutants from soils or water through plant uptake 66 . In this approach, the pollutants are not simply recycled back into the wetland, as is the case in phytostabilisation, but they are removed from the system by harvesting the plants or by volatilisation through the plants. The latter only applies to substances that can form gaseous compounds, such as Se 22, 67 and Hg 28 . For phytoextraction through uptake and harvest to be effective, uptake by the...

Table Of Contents

The Chemical Ecology of Pollutant Biodegradation Bioremediation and Phytoremediation from Mechanistic and Ecological Perspectives 5 3. Dendroremediation The Use of Trees in Cleaning up Polluted Soils 23 4. Methods for Rhizoremediation Research Approaches to Experimental Design and Microbial Analysis 33 5. Constructed Wetlands for Phytoremediation Rhizofiltration, Phytostabilisation and 6. Influence of Helophytes on Redox Reactions in their Rhizosphere 69 A. Wiessner, P. Kuschk, U....

Preventing Establishment By Transgenic Mitigation

If a transgene confers even a small fitness disadvantage, the less fit transgenic volunteers and their own or hybrid progeny should only be able to exist as a very small proportion of the population. Therefore, it should be possible to mitigate volunteer establishment and gene flow by lowering the fitness of transgene recipients below the fitness of competitors, so that the volunteer or hybrid offspring will reproduce with considerably less success than its non-transgenic competitors. A concept...

Days

Time course experiment of lindane disappearance in solution with chilli and coriander. Controls (white columns), chilli (black columns), coriander (grey columns). Data points represent the means of 5 replicates determinations. Bar SD. the effect of the rhizosphere on these compounds. Five plant species were harvested and separated into roots, stems and leaves Chenopodium vulgare, Solanum nigrum, Cytisus striatus, Vicia sativa and Avena sativa. Concentrations of total HCH in plant...

Oxygen Release By Roots Into Rhizosphere Of Helophytes

Oxygen reaching the root aerenchyma is respired by the root tissues and diffuses towards to the root apex and radially to the rhizosphere, to be consumed in the surrounding soil 54 . The oxygen flux from the root aerenchyma to the rhizosphere, known as radial oxygen loss (ROL), is determined by the concentration gradient, the consumption of oxygen by the cells along the radial path, and the physical resistance to oxygen diffusion 54, 56 . As a result, 30-40 of the oxygen supplied via the...

Rhizosphere Ecology

Yu et al., reported the recovery, by three to four orders of magnitude, of more resin acid degraders (tricyclic terpenoids originating from softwood trees) in hydrocarbon-contaminated soils than in pristine Arctic tundra soil 60 . Notably, the soil samples were collected thousands of kilometres from the nearest source of resin acids (conifer forest) and contained no native resin acids. The bacteria isolated in the study, Pseudomonas and Sphingomonas, are hydrocarbons degraders, which suggested...

Organic Compounds

It was shown that dissipation of condensed PAHs might be enhanced in the presence of AM fungi in the soil spiked with a mixture of different PAHs 127 . These results were consecutively verified in pot experiments conducted in two different industrially polluted soils 128 . In general, following explanations were suggested by the authors to elucidate the contribution of AM to PAH degradation i) mycorrhiza modifies root enzyme activity, exudation and architecture in a manner that stimulates PAH...

Sage

Serial analysis of gene expression (SAGE) is a method that allows the quantitative and simultaneous analysis of a large number of transcripts 42 . The first application of this technique in higher plants was used for profiling expressed genes in rice (Oryza sativa L.) seedlings 43 . Recent applications of SAGE technique in plants consist of wood formation in loblolly pine 44 gene expression pattern in the crop plant cassava (Manihot esculenta) from viral disease resistance and susceptible...

Phytoremediation

The uptake of pesticides by plants depends on the physicochemical properties of the compound, mode of application, soil type, climatic factors and plant species. Once in the roots, the chemical may be translocated to shoot via xylem. The permeation from plant roots to xylem is optimal for moderately hydrophobic molecules, with a log Kow between 0.5 and 3.5. More hydrophobic chemicals tend to bind with lipid membranes or oil possibly present in plant roots. Translocation of non-ionic pesticides...