We are searching data for your request:
Upon completion, a link will appear to access the found materials.
By National University of Quilmes
Everything we need and want to know about transgenic food and seeds
Humanity has cultivated and harvested plants for ten or fifteen thousand years. However, most of the technological innovations in agriculture have taken place during the last two hundred years. These include both mechanization and hybridization, agrochemicals (herbicides and pesticides), and chemical fertilizers.
All these advances have been related to the changes that took place in societies: transition from nomadic life to sedentary life, population growth in cities and, fundamentally, demographic growth.
The need to feed more and more people and the need to have food with higher nutritional values, have been two of the great challenges of Humanity.
Breeders and growers used family similarity - "likeness" - to improve the productivity of animals and plants. For example, they chose to grow the largest plants, or the strongest, or the least prone to disease; Thus, agricultural producers were selecting, choosing, those that it was convenient for them to maintain and use in food production. They didn't know it but they were making use of genetic selection.
The laws governing the transmission of genetic characteristics remained a mystery until the late 19th century when the monk Gregor Mendel began studying heredity in garden plants (peas). Through very well planned experiments and calculations of probabilities (since he was an experienced mathematician), he was able to conclude that some invisible particles carried the hereditary characteristics and that these characteristics were passed from generation to generation. As we know, these laws were "rediscovered" in the first decades of the 20th century.
Towards the 50s - more precisely in 1953 - a fundamental change took place in the biological sciences with the determination of the structure of DNA (deoxyribonucleic acid). The theoretical model, developed by James Watson and Francis Crick, allowed scientists to understand how genetic information is stored in cells, how that information is duplicated, and how it is passed from generation to generation.
A revolutionary technological leap occurred in the 70s when genetic information began to be handled, that is, to know how to place a gene (DNA fragment that has the information for a certain protein) of one species in another or from one individual of a species into another individual of the same species.
This, known as genetic engineering or recombinant ADINI technology, led us to begin to produce human drugs (such as insulin, growth hormone or erythropoietin) in quantities and qualities previously impossible to produce.
For this, it was necessary to manufacture the first transgenic bacteria, that is, to place other genes inside the cell of microorganisms to produce, for example, human insulin.
Later it was possible to introduce genes with specific characteristics in animal cells, in insect cells, in yeasts (such as those used in breweries and bakeries), in animals and, mainly, in plants.
Biotechnology is a new information technology, which is closely linked to the advancement of Science, in which today there is practically no clear separation between research and application.
For centuries agricultural producers have improved crops through selection and hybridization, the controlled pollination of plants. Biotechnology in plants is an extension of these techniques but with the important difference that it allows transmitting a greater variety of genetic information with greater precision and control.
Traditional plant cultivation involves the crossing of hundreds of genes, while biotechnology allows the transfer of only one or a few of the desirable genes. In this way, this technology makes it possible to obtain and develop cultivars with certain specific beneficial characteristics and eliminating or controlling those that may be undesirable.
Thus arose the first transgenic plants that have characteristics of resistance to herbicides, insects and diseases; then followed those that have the possibility of incorporating genes to produce amino acids (bases for the construction of proteins), vitamins, fatty acids beneficial for our diet, etc., but also those that lead to improving the industry: cotton plants with new characteristics of their fibers or those that produce biodegradable plastics.
Finally, the production of drugs (vaccines, antibodies or anticoagulant proteins) has already begun to be developed in plants and animals, what has been called molecular pharming (something like ', molecular agropharmaceuticals ") in what refers to the production and nutraceuticals (or "nutritional drugs") to products.
This great change has already started and transgenic herbicide resistant plants are its first manifestation.
What is a transgenic plant?
A transgenic plant is nothing more and nothing less than a plant to which an extra gene has been introduced (that is, a portion of DNA that has the necessary information for the synthesis of a protein to occur) from another organism, be it from another plant, a bacterium, or even an animal. That is why it is called transgenic, because a new gene has been added to the more than 100,000 that it already naturally had.
Why is a new gene added to a plant?
Generally to provide it with some special characteristic that is useful for the producer, such as, for example, resistance to herbicides, insect pests, viruses or extreme conditions. In short, improved crops are sought.
In Argentina, transgenic cultivars are in full use; the most widespread is RR soy, with resistance to glyphosate, although there are also other cultivars, such as corn with resistance to attack by insects of the Lepidopteran family.
How do you make a transgenic plant?
The first transgenic laboratory plants were developed during the 1980s. Scientists took advantage of gadgets made by a naturally occurring bacterium, which infects plants, producing very characteristic tumors. This bacterium is called Agrobacteríum tumefacíens (At) and, in order to survive, it dedicates itself to introducing foreign genes to the plants that then provide it with nutrients. In short, it has manufactured transgenic plants for thousands of years and in a natural way.
The way that At works is as follows: a plant stem or leaf that has a small superficial wound is infected by the bacteria, which colonizes the tissue, as in any infection. The next step & # 8209; unlike other bacterial infections & # 8209; At this he manages to introduce into the plant cells of plant tissue a portion of DNA, which contains several genes. The portion of DNA introduced is delimited by well-recognizable ends and (in some way not yet determined) it integrates with the rest of the genes of the plant cells. These introduced genes, generically called 'tumor genes', produce proteins like any other gene, but, unlike natural plant proteins, these proteins are used to synthesize compounds that provide nutrients to the bacteria and that, in addition, cause the uncontrolled growth of plant tissue that produces the characteristic tumor of infection with At.
By unraveling this mechanism of action of the bacteria, scientists intuited the first procedures to obtain genetically modified plants in the laboratory & # 8209 ;. If the tumor genes of the portion of DNA that At introduces into the plant are replaced and, in their place, other genes are inserted that make proteins that can give the plant some desired characteristic, we will obtain a transgenic plant, improved for agriculture .
The first transgenic plants were developed with these techniques and the genes that were used to give new characteristics to the modified plants were genes of bacteria that, for example, provide resistance to lepidopteran insects. This is the case of the genes called cry, possessed by the bacterium Bacillus thuringíensís, which manufacture a set of proteins that destroy the stomach epithelium of the insects that consume them. When these genes were isolated, they were introduced by means of Agrobacterium tumefaciens in different cultivars, thus achieving the control of some pests.