Role of genetically modified crops in agriculture
Genetically Modified crops are those plants, whose DNA has been altered using genetic engineering techniques. Mostly the aim is to introduce a new trait to the plant which does not occur naturally in the species. For examples resistance to pests, diseases, environmental conditions, resistance to chemical treatments the production of a certain nutrient and pharmaceutical agent.
METHOD OF PRODUCING GENETICALLY MODIFIED ORGANISM:
Genetically engineered plants are generated in a laboratory by altering their genetic makeup. This is usually done by adding one or more genes to a plants genome using genetic engineering techniques. Most genetically modified plants are generated by the biolistic method (particle gun) or by Agrobacterium tumefaciens mediated transformation. Plant scientists, backed by results of modern comprehensive profiling of crop composition, point out that crops modified using GM techniques are less likely to have unintended changes than are conventionally bred crops. Tobacco is the most genetically modified plant, due to well-developed transformation methods, easy propagation and well-studied genomes. They serve as model organisms for other plant species.
In the biolistic method, DNA is bound to tiny particles of gold or tungsten which are subsequently shot into plant tissue or single plant cells under high pressure. The accelerated particles penetrate both the cell wall and membranes. The DNA separates from the metal and is integrated into plant genome inside the nucleus. This method has been applied successfully for many cultivated crops, especially monocots like wheat or maize, for which transformation using Agrobacterium tumefaciens has been less successful. The major disadvantage of this procedure is that serious damage can be done to the cellular tissue.
Agrobacteria are natural plant parasites, and their natural ability to transfer genes provides another method for the development of genetically engineered plants. To create a suitable environment for them, these Agrobacteria insert their genes into plant hosts, resulting in a proliferation of plant cells near the soil level. The genetic information for tumour growth is encoded on a mobile, circular DNA fragment. When Agrobacterium infects a plant, it transfers this T-DNA to a random site in the plant genome. When used in genetic engineering the bacterial T-DNA is removed from the bacterial plasmid and replaced with the desired foreign gene. The bacterium is a vector, enabling transportation of foreign genes into plants. This method works especially well for dicotyledonous plants like potatoes, tomatoes, and tobacco. Agrobacteria infection is less successful in crops like wheat and maize.
Introducing new genes into plants requires a promoter specific to the area where the gene is to be expressed. For instance, if we want the gene to be expressed only in rice grains and not in leaves, then an endosperm-specific promoter would be used. The codons of the gene must also be optimized for the organism due to codon usage bias. The transgenic gene products should also be able to be denatured by heat so that they are destroyed during cooking.
WHERE IS GM FOOD PRODUCED?
In 2011 a total of 29 countries were officially growing one or more GM crops.
• Argentina: GM soy, corn, cotton.
• Australia: GM cotton, canola, wheat.
• Bolivia: GM soy.
• Brazil: GM soy, corn, cotton.
• Canada: GM corn, soy, canola, sugar beet.
• China: GM cotton, papaya, poplar, tomato, sweet pepper.
• India: GM cotton.
• Pakistan: GM cotton.
• Paraguay: GM soy.
• South Africa: GM corn, cotton.
• Uruguay: GM soy, corn.
• USA: The worlds biggest producer of genetically modified foods. GM food is widely used. 80-90% of all corn, soybeans and cotton are GM. Canola, squash, papaya, alfalfa and sugar beet also have a large portion of GM.
ROLE OF GM CROPS IN AGRICULTURE:
Transgenic plants have a lot of advantages both for producers, farmers, industry, consumers, environment and the human future. Due to high regulatory and research costs, the majority of genetically modified crops in agriculture consist of commodity crops, such as soybean, maize, cotton and rapeseed.
THE PRODUCTION OF THE NEW VARIETIES:
A high efficiency in plants amelioration is obtained. The techniques of gene transfer are more precise because they allow the insulation and the propagation of the interest gene, while the classical hybridization techniques use the entire parental genomes and for this reason are needed back crossings to emphasize the manifestation of a parental gene or to eliminate some secondary unwanted effects determined by the action of the gene in the genome.
ROLE OF GM CROPS IN CROP PRODUCTIVITY:
First of all the process of pests destroying is simplified due to the elimination of Herbicides in the pre-emergent period and in the vegetation period. For the GMO only one total herbicide is necessary. On the other hand, the production output is increasing as well as the profit of the transgenic cultures; even the obtaining cost of the GMO is rather high.
a) Role of GM crops in industrial processes:
Due to the new properties of the transgenic plants, their processing could be also improved, as is the case of the modified starch, of low lignin content wood (in this case the paper manufacturing is less pollutant), of bio-plastics, of some human protein production (easier and in higher quantities, for therapeutic aim).
b) Advantages of GM crops for consumer:
Nowadays the fruits and the vegetables with delayed maturation are easier stored, with minimum losses. The maturation moment can be controlled according to the demands of the marked. In the future it is considered that the transgenic plants can determine an improved human health due to the higher content of vitamins, minerals, essential amino acids, by using the vaccine plants, the rice enriched in pro-vitamin A, etc.
c) Role of GM crops for environment protection and human future
First of all, transgenic plants imply a lower pollution due to lower quantities of pesticides. Then, higher agricultural productions are obtained and people hope to eliminate the starving in the world (by extension of the areas cultivated with GMO resistant against salted soils, acid soils, lower temperatures, etc.)
d) Role of GM crops in Production of bio fuels:
Algae, both hybrid and GM, is under development by several companies for the production of biofuels. Jatropha has also been modified to improve its qualities for fuel product. Swiss-based Syngenta has received USDA approval to market a maize seed trademarked Enogen, which has been genetically modified to convert its own starch to sugar to speed the process of making ethanol for biofuel. In 2013, the Flemish Institute for Biotechnology was investigating poplar trees genetically engineered to contain less lignin so that they would be more suitable for conversion into biofuels. Lignin is the critical limiting factor when using wood to make bio-ethanol because lignin limits the accessibility of cellulose micro fibrils to DE polymerization by enzymes.
Genetically modified plants have also been used for bioremediation of contaminated soils. Mercury, selenium and organic pollutants such as polychlorinated biphenyls (PCBs), TNT and RDX explosive contaminants have been removed from soils by transgenic plants containing genes for bacterial enzymes.
The authors are associated with the Department of Agronomy University of Agriculture, Faisalabad, Pakistan.
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