Transferred to plants

Shillito, R.D., Paszowski, J. Potrykus, I. (1985). High efficiency gene transfer to plants. BiolTechnology, 3,1099-103. 

Chemical separation of technetium in soils is not easy, but it is fairly well-known that under aerobic conditions pertechnetate Tc(YII) is readily transferred to plants while under anaerobic conditions insoluble TcCh (or its hydrate) is not transferred to them. Even under aerobic conditions, however, the transfer rate decreases with time [28], indicating that soluble pertechnetate changes to insoluble forms by the action of microorganisms which produce a local anaerobic condition around themselves [29,30]. Insoluble technetium species may be TcOz, sulfide or complexes of organic material such as humic acid. 

Irrigation water used in crop production represents one of the most significant sources of contamination in fresh produce production. Contamination from manure heaps can readily be transferred to the water course via run off and subsequently disseminated over large distances via streams or rivers. When contaminated, water is used to irrigate crops, human pathogens can be directly transferred to plant tissue and persist through to harvest. 

Implemented by 37 C.F.R. 401, http //www.access.gpo.gov/nara/cfr/waisidx 02/37cfr401 02. html. Broothaerts, Wim, Heidi J. Mitchell, Brian Weir, Sarah Kaines, Leon M. A. Smith, Wei Yang, Jorge E. Mayer, Carolina Roa-Rodrfguez, and Richard A. Jefferson. 2005. Gene transfer to plants by diverse species of bacteria. Nature (Letters) 433(February 10) 629—633. http //www.bios.net/daisy/bios/393/version/live/part/4Zdata (accessed June 9, 2006). 

I. Potrykus and G. Spangenberg (eds.). Gene Transfer to Plants, Springer, Berlin, 1995. 

Soil contaminants in both the rooting zone and the surface-soil layer can be transferred to edible parts of vegetation by a number of processes. Contaminants in the rooting zone are transferred to plants through root uptake. The partitioning of contaminants between soil and root tends to increase with increasing... 

Soil contamination can contribute to human toxic exposure via a number of routes. These include plant uptakes of soil pollutants, including fertilizers and pesticides, that are either eaten by people directly or passed up the food chain, absorption onto the skin and subsequently into the bodies of grazing animals to be passed up through the food chain by animals, and via contaminated airborne soil particles that are ultimately inhaled by humans. Soils contain large lipophilic components that absorb lipophilic chemicals which are subsequently transferred to plants, animals, and to the air. Water distributed in soil dissolves hydrophilic chemicals and acts as a conduit for ultimate human absorption, through plants and thus up the food chain from whence they ultimately impact humans. 

Performance of field trials over extended periods to stndy persistence and biodegradation nnder conditions of agricnltmal practice and to stndy possible transfer to plants nnder normal and extreme conditions. 

Since the second edition appeared, much of the interest in soil chemistry has been on the fate of so-called toxic chemicals and elements in soils. This edition points out that (1) all of the chemical elements—toxic and beneficial—were always in the soil, (2) the soil is the safest part of the environment in which to deposit our wastes, (3) there are wise and unwise ways to utilize soil for waste disposal, (4) soil chemistry degrades wastes and converts them into benign or useful substances, (5) environmental activists and the popular media usually ignore the dose-response concept that is central to toxicology and to soil fertility, and (6) how much is in the soil, how fast it is changing, and how easily it transfers to plants and water are more important than what is there. Soil chemistry can answer those important questions. A goal for the future is to answer them better. 

Fig. 1. A widely used method for DNA transfer to plants makes use of the natural DNA transfer system of Agrobacterium tumefaciens. Virulence genes located on the Ti plasmid (vir-region) are part of the machinery by which the T-DNA-protein complex (T-complex) is transferred from agrobacterium to the plant cell nucleus. Here the T-DNA is inserted into the plant genome.

In plants, [2Fe-2S] ferredoxins are involved in conjunction with ferredoxin-reductase in photosynthesis reactions and the transfer of electrons from photosystem I to NADP . However, evidence for involvement of ferredoxins in electron transfer to plant P450s awaits a more detailed characterization of the multiple P450 systems present in the biotechnologically important plant species. 

Effect of arbuscular mycorrhizal (AM) fungi on heavy metal and radionuclide transfer to plants... 

Heavy metal and radionuclide concentrations in soils increase due to man-made pollution. One of the first entry points of such elements into plant ecosystems is the rhizosphere, defined as the soil under the biological, physical and chemical influence of roots. Arbuscular mycorrhizal (AM) fungi, symbiotic microorganisms associated with the roots of many plant species, provide a direct link between soil and roots and affect metal transfer to plants. The present chapter includes recent laboratory work and some research aspects stiU to be adressed on the contribution of AM fungi to plant metal uptake. The necessity to develop new and adapted approaches, such as compartment devices and root-organ cultures, to separate AM to root contribution to metal uptake is emphasized. Available data may be difficult to compare because they were obtained under different experimental conditions. However, they suggest that the transfer of heavy metals from AM fungi to plants may be metal specific. Further research should focus on the mechanisms involved in reduced or improved uptake of metals by mycorrhizal plants, on AM tolerance to metals and radionuclides and on AM functional diversity in polluted soils. AM contribution to metal uptake should also be quantified to include data in models of plant uptake. 

Tibazarwa C., Corbisier R, Mench M., Bossus A., Solda R, Mergeay M., Wyns L., and van der Lelie D., A microbial biosensor to predict bioavailable nickel in soil and its transfer to plants. Environ. Pollut., 113, 19-26, 2001. 

The mobility and scal-to-plant transfer of Sr, Cs and ii Ag in two Mediterranean sandy and sandy-loam soils have been studied . The relative transfer to plants of Cs and Sr follows the predictions but radiosilver was found to be less mobile than expected. Silver complexation and reduction may play a certain role in its behaviour . The behaviour of radionuclides in the Chernobyl area should be compared with theoretical schemes concerning the behaviour of accidentally released radionuclides in agricultural systems. In a study , silica gel bearing chemically immobilized humic acid was used to model the uptake of i Ag+ and I by humic matter. The absorptive properties of humic acid, as judged by the uptake of these radionuclides, are quite distinct from those of the parent silica gel. 

Duarte-Davidson R, Jones KC (1996) Screening the environmental fate of organic contaminants in sewage sludge applied to agricultural soUs. 11. The potential for transfers to plants and grazing animals. Sci Total Environ 185 59-70... 

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