Genetically Modified Foods
Hunger and malnutrition of the rapidly growing human population is one of the major problem faced by the present world. Genetically modified food (GM Food) is the solution offered by our scientific community to cope with this problem.
The food produced on a massive scale, by direct or indirect involvement of genetically manipulated organisms is called genetically modified food.
Genetic modification is an inherent event in nature driven by the sexual reproduction in living organisms. It is the excellence of man who invented conventional methods of selective and mutational breeding to yield desirable and beneficial genetic modifications in both plants and animals.
Advancement of Biotechnology resulted in a novel method of artificial genetic manipulation called Genetic engineering. It is primarily based on recombinant DNA technology. It is this technology which is utilized in the production of genetically manipulated organisms (GMO's) that could be involved directly or indirectly in the production of GM food.
GM foods are associated with many controversial issues; primarily these are addressed by conflicts over the relative pros and cons of GM foods.
Major biotech companies like ‘Monsanto' and ‘Cargill' are promoting GM foods by focusing only on their beneficial aspects, giving least importance to their negative effects on safety, environment and biodiversity. On the other hand, governmental regulators and nongovernmental organizations, along with some scientists, are strictly opposing this type of blind promotion of GM food by enlightening the people on their negative effects.
The controversies associated with GM foods include issues such as safety, environmental benefits and risks, biodiversity, and ethical and social considerations.
GM foods are implicated for adverse human health risks like allergencity, unintentional harm to other organisms resulting in abnormal biodiversity, environmental hazards such as development of super weeds, and pesticide and antibiotic resistance in disease causing organisms. On the other hand, GM foods are also responsible for advantages such as improvement of nutrition and development of economically beneficial agricultural crop plants with pest resistance, herbicide tolerance, and cold and drought tolerance. They are also responsible for the development of eco-friendly organisms that help in cleaning the polluted environment.
It is the public's concern about GM food that decides either their promotion or hindrance. In regions like Europe the promotion of GM foods is strictly opposed, whereas in the U.S. 2/3 of the population has already started using GM food in their daily diet.
Many products of GM foods such as Flavr Savr tomatoes, Bt corn, Bt cotton, soybeans, Hawaiian papaya, etc., are introduced into the market and are successful over their conventional alternatives. To date, there has been no substantial evidence proving the disadvantages implicated with these foods.
Methods involved in the production of GM foods
As we know, genetically modified foods are derived from either the direct or indirect involvement of genetically modified organisms (GMOs); Genetic modification is the key process for the production of GM foods.
Genetic modification of organisms can be obtained in two ways
1) Conventional methods
2) Genetic engineering
Traditionally farmers have been using conventional methods like selective and mutational breeding in both animals and plants to obtain novel and beneficial varieties with desirable characteristics, such as high crop yield, resistance to disease, high growth rate, etc.,
Genetic engineering is the recent advancement of Biotechnology through which specific genes responsible for desirable characteristics can be exchanged between the genomes of source and target organisms.
The word “Genetic Engineering” was coined by Jack Williamson in his science fiction novel Dragon's Island published in 1951(Morgan, Sally, 2003). Later scientific contributions, such as the discovery of DNA structure by Watson & Crick and the isolation of restriction endonucleases by Daniel Nathans & Hamilton Smith, led to this new technique of artificial genetic manipulation (British Medical Association, 1999).
Synthetic human insulin was the first genetically engineered drug produced and approved by the FDA in the U.S. in the year 1982. Flavr Savr tomatoes were the first GM food produced and commercialized (Lemaux, 2008).
Genetic engineering is otherwise known as Recombinant DNA technology and can be done in the following the steps:
Isolation of the gene responsible for desirable characteristics in the source organism and its amplification;
Insertion of the gene into a vector;
Transfer of the recombinant vector to the target organism; and,
Selection of genetically modified organism.
The genes responsible for desirable characteristics are isolated from the genome of the source organism by using specific restriction endonucleases that cut at specific sites on the source organism's DNA to isolate the desired gene with sticky ends. This isolated gene has to be amplified either by using cloning vectors or by the advanced method like Polymerase chain reaction (PCR).
The isolated gene has to be incorporated into the genome of the transfer vector, which is expected to transfer the gene of interest to the target organism. There are three methods available based on the target organism to be transformed: Plasmid vector method; Viral vector method; and Biolistic method (Tester M, 2002).
Extra chromosomal material called plasmid in prokaryotes like bacteria is utilized as vector in plasmid vector method. It was the first discovered and most popular out of the three methods for artificial gene transfer. In this method, first the isolated gene of interest has to be incorporated into the plasmid DNA using the same restriction enzymes that were used to isolate the gene of interest. And the DNA ligase is used to join the sticky ends generated in the gene of interest and the plasmid DNA both resulting from restrictive digestion, which ultimately results in recombinant vectors. The selection of recombinant vectors from non-recombinant vectors is done by exploiting the antibiotic resistant characteristic inherent in the plasmid. The recombinant plasmid vectors are transferred to the target organism by a transformation process, consequently resulting in the expression of the gene of interest in the target organism. This method is mostly used to produce genetically modified bacteria that can produce commercially valuable proteins.
The controversy associated with this method is that it can allow the transfer of the gene of interest to organisms other than the target organisms, which may allow unwanted expression of gene product in those organisms. But usually the bacteria produced by this method in the laboratory will not come into contact with natural bacteria.
The viral vector method also uses a similar strategy as the previous method, using viral DNA instead of plasmid DNA as transfer vector. This method is mostly used to produce genetically modified animals and plants.
The controversy associated with this method is that it may allow unpredictable insertion of genes of interest in target genomes, which might interfere with an essential gene function in the target organism. Moreover, people are much concerned about the GM food derived from GMOs produced by this method, as it involves deliberate infection with a virus even though it is a disabled one.
Biolistic method is a direct method of gene insertion, otherwise called the gene gun method. It involves high velocity bombardment of metal beads coated with the gene of interest onto the target organism. Generally it is used to engineer plants. This method also faces similar criticism, as it also involves the possible interruption of working genes in target plant.
Advantages of rDNA technology over conventional methods
Genetic modification through conventional methods involves modification of a vast number of genes at one time, which may include additional undesirable modifications. Whereas with rDNA technology, we can modify a single specific gene of interest without disturbing other genes.
In conventional methods, exchange of genetic material is limited to closely related species within a genera; in contrast, rDNA technology allows exchange of genetic material across kingdoms, i.e., genes can be exchanged between organisms belonging to the bacterial or animal kingdoms to organisms in the plant kingdom.
Through genetic modification involving rDNA technology, one can precisely control the production of gene product at a specific place and in a specified time, which is not possible with the conventional methods (Lemaux, 2008).
Non-Biotechnological alternative method
Marker assisted selection (MAS), the non-biotechnological method available for conventional breeders as a substitute to rDNA technology, can offer similar precision and specificity in identifying desirable or deleterious genes for the purpose of genetic modification in organisms (Lemaux, 2008).
Markers are additional traits that are closely linked to the desirable traits, and they can help in indirect selection of desirable traits in the organisms. MAS is a valuable method for organic farmers, which have allowed them to produce hybrid varieties of food crops with desirable characteristics from wild varieties, using the conventional method of selective crossing. As these hybrid crops and their food products are produced in non biotechnological methods without involving rDNA technology, they are known as “Super Organics,” and they are devoid of risks that are expected with the genetically engineered food crops and their food products.
But this method is limited to sexually compatible organisms. It cannot help in cases of combining desirable characteristics from two different sexually incompatible organisms, which can be achieved only through genetic engineering.
Applications of the technology
Development of economically beneficial crops with pest resistance, herbicide tolerance, and disease resistance that can help farmers avoid using pesticides, and protect field crops from both herbicides used to destroy field weeds and from disease causing organisms, such as viruses and bacteria respectively.
Development of GM plants that can tolerate extreme weather, such as cold, drought, and salinity. Cold resistance genes like antifreeze genes incorporated in plants, avoid unexpected frost destruction of seedlings.
Genetic manipulation of foods to have additional nutrients, for instance genetic manipulation of rice to increase beta carotene (vitamin A) content thus avoiding vitamin A deficiency in populations using rice as their staple food(Deborah B. Whitman, 2000).
Production of edible vaccines and medicines as ingredients in daily usage products like vegetables, milk, meat, etc.
Risks of the technology
Development of allergenic reactions in people from consuming GM foods, which sometimes may lead to risk of death.
Pest resistant varieties of agro plants may increase the mortality rate of certain organisms, thus interrupting the food chain in the ecosystem. There is a chance of developing pesticide resistant insects and pests, which will reduce the efficiency of pesticides.
Cross breeding of herbicide tolerant crop plants with weeds may lead to development of herbicide resistant weeds called super weeds (Deborah B. Whitman, 2000).
Ethical and Societal considerations
Ethically it is inappropriate to engineer plants with “suicidal genes” to introduce male sterility. Even though it prevents the risk of spreading transgenes through pollen, it promotes male sterility in natural plants. Some large biotech companies like Monsanto have introduced methods, such as issuing licenses to breed genetically modified seeds and developing GMOs that produce sterile seeds, to secure genetically modified seeds from deliberate theft by farmers. But these methods disable the farmers from propagating seeds from their previous crop for their next crop, and it forces them to buy seeds for every crop. This is unethical, as it results in loss of farmers' intellectual property right to benefit from their traditional breeding work (Xenia K. Morin, 2008). Artificial manipulation of genes in organisms is religiously considered as tampering with nature, which is unethical. Genetic engineering of animals for human benefits results in considerable stress to them, which is ethically inappropriate.
Some people in society consider the genetic manipulation of organisms for the purpose of GM food as the transformation of nature into industry. A few think that GM food production is expensive and will promote only the rich countries, whereas poor countries will remain poor as they cannot afford such expensive technology. Most people think that Genetic engineering is an invaluable technology for the welfare of mankind, and GM food is a promising solution for the increasing population problem.
GM foods are invaluable resources offered to mankind by the scientific community. People should be enlightened about its vast advantages over the few disadvantages. GM foods must be thoroughly tested and labeled, they must be approved by governmental organizations like the FDA, and they should be made available to consumers at the least possible cost. The background technology, i.e., genetic engineering, is an invaluable technology to the scientific community to solve many scientific mysteries. Using this technology we can solve major world problems such as pollution, drought, animal and plant diseases, and hunger and malnutrition. This technology should be made available to all nations in the world; so that most of the developing and under developed countries can utilize it to produce adequate amounts of food that can fulfill the increasing food demands of their exploding population. Regarding the risks that are expected with GM foods, until now no GM food released to the market has been proven to be harmful in any respect.
1. Peggy G. Lemaux. 2008. Genetically Engineered Plants and Foods: A Scientist's Analysis of the issues (Part I). Annu. Rev. Plant Biol. 59:771-812.
2. Deborah B. Whitman. 2000. Genetically Modified Foods: Harmful or Helpful. CSA Discovery guides.
3. Tester, M., 2002, Some GM facts (book review), Science 298: 1341-1342
5. Morgan, Sally. 2003. Super foods: Genetic Modification of foods (Science at the edge). Heinemann ISBN 1-4034-4123-5
6. British Medical Association (1999). The impact of Genetic modification on Agriculture, Food and Health. BMJ Books. ISBN 0-7279-1431-6.
7. Xenia K. Morin., 2008. Genetically modified food from crops: progress, Pawns and possibilities. Anal Bioanal Chem. 392:333–340.