Genetically modified plants genetic modification

A still lower-cost route to PHAs is genetic modification of plants to directly produce the final polymer. Monsanto (and others) pursued this approach and is currently being cofunded by the US Department of Energy (DOE) in a collaborative research project led by Metabolix. Switchgrass will be modified to produce PHAs, which can then be extracted from the plant material and processed to obtain a consistent composition and the desired material properties. The plant material remaining after PHA extraction can be used to produce fuels, power, or other products, creating the opportunity for a "plants as factories" biorefinery. Applications for polymers with properties similar to those of PHAs consume on the order of 13.6 million metric t annually, and it is possible that in the future PHAs will figure prominently in the plastics market. 

Advanced genetic engineering techniques are being used to improve existing renewable feedstocks for the production of industrial bioproducts. In some cases, the feedstock composition is modified to increase the content of a desired component and/or decrease the content of an undesired component, whereas in others, a new metabolic pathway is inserted into the plant genes so that the modified plant produces an entirely new component. These research efforts are recent, and very little, if any, published information is currently available. However, we provide brief descriptions of the research activities to give perspective on the opportunities for new industrial bioproducts that may emerge from feedstock modification. 

There is much controversy, at least in Europe, concerning genetic modification of plants. The three major crops affected so far are maize, soyabean and rapeseed. All of these, in addition to their other uses, are sources of oil. The reasons for modification in all these cases are related to herbicide tolerance and resistance to insects. For the varieties generally available at present, there is no known difference from non-modified strains with respect to fatty acid composition, oil yield, tocopherol level, or the level of any other minor oil constituent. 

Many consumers also wish to be made aware of any genetic modification to the crop. Genetic modification might be beneficial for cocoa butter production as the characteristics of the butter could be modified in the growing bean, and also resistance to pests and diseases might be introduced to the plant. Analytical methods are required to detect such modification, in both the raw materials and the processed product. 

Finally, genes required for particular aspects of fatty acid and triacylglycerol biosynthesis can be identified in appropriate sources, cloned, and transferred to other plants. Rapeseed has proved to be particularly flexible in this respect, and its fatty acid composition has been modified in several ways, some of which have now reached or are very close to commercial application (Section 9.4). Genetic modification procedures are also applied to soybean and other oilseed crops. 

Gunstone, ED. and Pollard, M.R. (2001) Vegetable oils with fatty acid composition changed by plant breeding or by genetic modification, in Structured and Modified Lipids (ed ED. Gunstone), Marcel Dekker, Inc., New York, NY, pp. 155-184. 

Animal and Plant Health Inspection Service, United States Department of Agriculture. Updated information on field test notifications and modifications of genetically modified plants can be obtained from several Internet addresses via gopher, ftp, telnet, or WWW (http //) including "ftp.nbiap.vt.edu,... 

Vegetable oil modification involves not only the FA qualitative and quantitative manipulations, but also the manipulation of components such as tocopherols and phytosterols. To fully characterize oils from genetically modified plants, these oils must be analyzed for their stereochemical stracture, which determines several oil properties and the suitability of the oil for various purposes. 

The most successful, in terms of application, has been herbicide resistance, where reduced utilization of herbicides has been claimed. Resistance against diseases (pests) has been one of the priorities in designing genetically modified (GM) plants. This also implies a decrease in the dependence on chemical pesticides. Genetic modification has been shown to provide an additional and less time-consuming tool, and to be a useful means of creating novel resistance, compared to classic breeding. 

With some specific exceptions, research and the development of genetically engineered animals has proven to be less straightforward than the genetic modification of plants and certainly more ethically problematic. In addition, although the public definitely shows some resistance to the idea of introducing genetically modified plants into the human... 

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