12-21-2012, 09:27 AM
The Goal
Application of genetic engineering in manipulation with plants has opened great perspectives for using plants in the future. The main goal of molecular plant biotechnology is the construction of new varieties of cultivated plants (Transgenic plants), and the development of new plant varieties that give better yield or nutrient power.
Therefore, genetically modified plants which possess resistance to insects, pathogens (primarily on viruses), herbicides, certain stressful environmental conditions, whose fruits rot slowly or plants with altered quality of oil or protein are already designed. In the year 2000, the total area sown with transgenic plants was 44.2 million hectares, and increase comparing to 1999 was 11%.
The transgenic plants are grown in 13 countries worldwide: in the United States (30.3 million hectares), Argentina (10 million hectares), Canada (3 million hectares), China (0.5 million hectares), South Africa, Australia, Bulgaria, France, Germany, Mexico, Romania, Spain and Uruguay. In the year 2000 it is the most planted were transgenic soybeans (25.8 million ha), maize (10.3 million hectares) and cotton (5.3 million hectares).
Transgenic plants tolerant to herbicides were represented with 74%. Transgenic plants resistant to insects were constructed by inserting the Bt gene responsible for synthesis of the protein toxic for insects (Bt toxin), which originates from the bacterium Bacillus thuringiensis. This plant was presented with the 19% of sown land. Data from 2004. are saying that the transgenic plants are grown in 16 countries around the world and cover more than 200 million hectares, and that the majority of transgenic plants are resistant to herbicides.
Impact on The Environment
Since the transgenic plants and the product of human activitiy, and could not be found naturally, studies on following the possible effects of using transgenic plants on the environment where grown. In many countries growing transgenic plants is regulated by rules defined in legislation. That way, it is detected that Bt insecticidal toxin excreted from the roots of transgenic maize after 40 days of cultivation in laboratory conditions, but around the roots of mature corn in the field too, while Bt toxin is not found in the ground on which the transgenic plants of corn were not grown.
Bt Toxin Toxicity
The presence of Bt toxin in the soil can cause the development of harmful insects that are resistant to the Bt toxin. Such cases initiated development of a system for quantitative detection of genetic modifications in corn. But, results of research that followed the breakdown of Bt toxins in different seasons and lasted for 200 days, showed that Bt toxin does not decompose completely in the soil. Far more extensive, 4-year studies of Bt toxin decomposition in corn leftovers in the field, showed that Bt toxin is extremely unstable in those remaining and that a small percent may exist even in firm parts of plants. There are results that when applied in the fields, Bt toxin product in the form of spray, can exist and is active in the soil for 28 months.
Agrobacterium tumefaciens is a soil bacteria, which causes the formation of tumors in infected plant by transferring genes located on the plasmid (genes for virulence) in the plant genome, using the information contained in part of plasmids called the T-DNA. Transferred DNA incorporates anywhere in chromosome of the plants. This property A. tumefaciens is used for construction of vectors for plant transformation by genes for virulence being replaced with genes that determine resistance to antibiotics, and with a gene that carries useful properties (eg. herbicide tolerance).
For gene expression, a promoter of cauliflower mosaic virus (CaMV
35S) is most commonly used. But, A. tumefaciens can enter the body of insects or animals, that feed on infected plants. Therefore, the question arises whether the T-DNA of Agrobacterium can infect animal cells. Experiments in laboratory have shown that this bacterium binds to and can steadily transformed HeLa, neurons, and kidney cells n the culture. It is even noted that the installation of T-DNA in the human cell chromosomes is done by the same mechanism by which this occurs in plant cells. Integrated T-DNA may have a mutagenic effect when incorporated into a chromosome. It is also stated that the viral CaMV 35S promoter is active in human HeLa cells.
Therefore, nowadays, the question of security of using transgenic plants for preparation of food for humans is frequently asked.
Application of genetic engineering in manipulation with plants has opened great perspectives for using plants in the future. The main goal of molecular plant biotechnology is the construction of new varieties of cultivated plants (Transgenic plants), and the development of new plant varieties that give better yield or nutrient power.
Therefore, genetically modified plants which possess resistance to insects, pathogens (primarily on viruses), herbicides, certain stressful environmental conditions, whose fruits rot slowly or plants with altered quality of oil or protein are already designed. In the year 2000, the total area sown with transgenic plants was 44.2 million hectares, and increase comparing to 1999 was 11%.
The transgenic plants are grown in 13 countries worldwide: in the United States (30.3 million hectares), Argentina (10 million hectares), Canada (3 million hectares), China (0.5 million hectares), South Africa, Australia, Bulgaria, France, Germany, Mexico, Romania, Spain and Uruguay. In the year 2000 it is the most planted were transgenic soybeans (25.8 million ha), maize (10.3 million hectares) and cotton (5.3 million hectares).
Transgenic plants tolerant to herbicides were represented with 74%. Transgenic plants resistant to insects were constructed by inserting the Bt gene responsible for synthesis of the protein toxic for insects (Bt toxin), which originates from the bacterium Bacillus thuringiensis. This plant was presented with the 19% of sown land. Data from 2004. are saying that the transgenic plants are grown in 16 countries around the world and cover more than 200 million hectares, and that the majority of transgenic plants are resistant to herbicides.
Impact on The Environment
Since the transgenic plants and the product of human activitiy, and could not be found naturally, studies on following the possible effects of using transgenic plants on the environment where grown. In many countries growing transgenic plants is regulated by rules defined in legislation. That way, it is detected that Bt insecticidal toxin excreted from the roots of transgenic maize after 40 days of cultivation in laboratory conditions, but around the roots of mature corn in the field too, while Bt toxin is not found in the ground on which the transgenic plants of corn were not grown.
Bt Toxin Toxicity
The presence of Bt toxin in the soil can cause the development of harmful insects that are resistant to the Bt toxin. Such cases initiated development of a system for quantitative detection of genetic modifications in corn. But, results of research that followed the breakdown of Bt toxins in different seasons and lasted for 200 days, showed that Bt toxin does not decompose completely in the soil. Far more extensive, 4-year studies of Bt toxin decomposition in corn leftovers in the field, showed that Bt toxin is extremely unstable in those remaining and that a small percent may exist even in firm parts of plants. There are results that when applied in the fields, Bt toxin product in the form of spray, can exist and is active in the soil for 28 months.
Agrobacterium tumefaciens is a soil bacteria, which causes the formation of tumors in infected plant by transferring genes located on the plasmid (genes for virulence) in the plant genome, using the information contained in part of plasmids called the T-DNA. Transferred DNA incorporates anywhere in chromosome of the plants. This property A. tumefaciens is used for construction of vectors for plant transformation by genes for virulence being replaced with genes that determine resistance to antibiotics, and with a gene that carries useful properties (eg. herbicide tolerance).
For gene expression, a promoter of cauliflower mosaic virus (CaMV
35S) is most commonly used. But, A. tumefaciens can enter the body of insects or animals, that feed on infected plants. Therefore, the question arises whether the T-DNA of Agrobacterium can infect animal cells. Experiments in laboratory have shown that this bacterium binds to and can steadily transformed HeLa, neurons, and kidney cells n the culture. It is even noted that the installation of T-DNA in the human cell chromosomes is done by the same mechanism by which this occurs in plant cells. Integrated T-DNA may have a mutagenic effect when incorporated into a chromosome. It is also stated that the viral CaMV 35S promoter is active in human HeLa cells.
Therefore, nowadays, the question of security of using transgenic plants for preparation of food for humans is frequently asked.
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