Myths And Realities About Transgenic Foods


2015-12-24 10:31:35



Hunger is the biggest crime and to a man with an empty stomach FOOD is God.

                                                                                                                                            ....... Mahatma Gandhi.

Any substance or material eaten to provide nutritional support for the body or for pleasure and usually consists of plant or animal origin, that contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals, and is ingested and assimilated by an organism to produce energy, stimulate growth, and maintain life is known as Food.

In the present century the world is facing acute shortage of food to feed the population of 6.5 billion peoples due to less agricultural land and productivity. Over 5.6 million children die each year as a result of malnutrition and hunger and 146 million children are underweight, many to a life-threatening degree. This figure represents 27 percent of children in developing countries. 146 million under-fives who are underweight, 57 million are found in India alone (Report, UNICEF). Fifty-six percent of deaths among pre-school children in the developing world are due to hunger and   malnutrition (WHO, Dec, 2010). Hence, we need every reasonable tool known to man to assure adequate nutrition for Earth's residents. GM foods, property utilized, can help meet these needs in a number of ways: pest resistance, herbicide tolerance, disease resistance, cold tolerance, drought tolerance and salinity tolerance, among others.

What’s a GMO and GM foods?

A GMO is a “genetically modified organism”: GM stands for genetically modified. The terms genetically-modified (GM) or genetically-engineered (GE) foods and genetically-modified organisms (GMOs) refer to crop plants created for human or animal consumption using the latest molecular biology techniques. These techniques of modern genetics have made possible the direct manipulation of the genetic makeup of organisms. Combining genes from different organisms is known as recombinant DNA technology and the resulting organism is said to be "genetically modified," "genetically engineered," or "transgenic." Plants of certain crops like soyabean, corn, cotton, sugar-beet and many others can be tweaked by scientists so that they develop desired properties like pest resistance or higher nutritional content. This tweaking is done through small changes in their genetic code - the DNA. Hence, they are called genetically modified (or engineered) crops. Food products made from such GM crops, like cornflakes from GM maize, are called GM foods.

GM foods were first put on the market in the early 1990s. Typically, genetically modified foods are transgenic plant products: soybean, corn, canola, and cotton seed oil. But animal products have also been developed. In 2006 a pig was controversially engineered to produce omega-3 fatty acids through the expression of a roundworm gene. Researchers have also developed a genetically-modified breed of pigs that are able to absorb plant phosphorus more efficiently, and as a consequence the phosphorus content of their manure is reduced by as much as 60%. Critics have objected to GM foods on several grounds, including perceived safety issues, ecological concerns, and economic concerns raised by the fact that these organisms are subject to intellectual property law.

The first commercially grown genetically modified whole food crop was a tomato (called FlavrSavr), which was modified to ripen without softening, by Calgene, later a subsidiary of Monsanto.


Types of genetically modified crops

Herbicide Tolerant

Producing plants that are tolerant to specific herbicides is one of the largest uses of plant genetic engineering. Herbicide tolerant crops "will allow nonpersistent herbicides (e.g. glyphosphate) to be more widely used and will permit postemergence spraying of herbicide-resistant crops." Herbicides work by effecting a single enzyme, which causes a metabolic change in the plant. There are three methods by which a plant can convey herbicide resistance:

  1. Producing an enzyme which detoxified the enzyme
  2. Producing an altered target enzyme which is not affected by the herbicide
  3. Producing physical or physiological barriers to the uptake of the herbicide

Plants have been genetically engineered to be tolerant of a wide variety of herbicides. For the simplicity of this paper, glyphosphate-tolerant plants will be used as an example. Glyphosphate is a synthetic herbicide and is the active ingredient in Monsanto’s herbicide Roundup®. Glyphosphate works by inhibiting the enzyme 5-enolpyruvyl-3-phosphoshikimic acid synthase (EPSPS), resulting in a disruption of the plants’ biosynthesis and ultimately death. A two-fold method has been used to produce crops that are glyphosphate-resistant. One part of the method uses recombinant DNA techniques to introduce plants that encode a glyphosphate-resistant EPSPS enzyme and the other introduces an enzyme that inactivates glyphosphate, glyphosphate oxidoreductase (GOX). Since crops are highly sensitive to glyphosphate, it was normally used as a pre-crop emergence herbicide. These new resistant cultivars will allow application both before and after crops emerge, with little to no crop damage.

Plants that have been field-tested include beets, corn, cotton, lettuce, poplar, potato, rapeseed, soybean, tobacco, tomato, and wheat.

There is a variety of other herbicide tolerant plants that exist or are currently being developed for similar use or for use as selectable markers to identify transformed plants. Other types of herbicide tolerance that has reached field-testing stages are listed below in Table.


Herbicides and herbicide-tolerant cultivars(Snow et. al, 1997)


Herbicide-tolerant plant


Cotton, potato, tobacco


Alfalfa, Arabidopsis, barley, beet, corn, creeping bentgrass, melon, peanut, poplar, rapeseed, rice, soybean, sugar cane, sweet potato, tobacco, tomato, wheat


Corn, cotton, grape, rapeseed, tobacco, tomato


Insect resistance

Devastation to crops by pests has been dealt with historically by the use of chemical pesticides. However, many of these chemicals have proven to be either ineffective or toxic. Therefore, a new strategy was needed and the miracle of recombinant technology answered the call. Plants have been produced that contain natural plant toxins that kill pests. The most common type of genetically engineered plant, the Bt plant, will be used here as an example for explanation purposes. Bt plants are created by inserting into a host plant’s genome the gene for Bacillus thuringiensis, a soil bacterium known to be a natural endotoxin. Bt toxins work by damaging the membrane or the pest’s midgut, then causing massive water uptake and eventually death. Bt toxin, however, is not harmful to humans or other invertebrates. It has been used naturally as an external pesticide, but breaks down quickly, especially in water. Transgenic Bt plants provide constant doses of the toxin and can kill pests in a single feeding. Monsanto Corporation has recently developed a Bt corn plant to combat infestations by corn rootworms. A more widely known Bt corn exists that aids in resistance to corn borers. Monsanto also produces a Bt tomato and potato, while Ciba-Geigy, Mycogen Corporation, Northrup King, and Genetique SARL have their own Bt corn products. Other insect-resistant plants have been made to produce lectins, which disrupt midgut epithelial cells, and inhibitors of certain digestive enzymes. However, none are as effective as transgenic Bt crops.

Disease resistance

Crops are susceptible to a variety of viral, bacterial, and fungal diseases. For example, a major invader of corn is Aspergillus flavus, which can be a threat to farm animals that eat contaminated feed. A. flavus gives off a carcinogenic by-product called aflatoxin, known the cause hepatitis, cirrhosis, and death in many countries. For this reason as well as many others, recombinant technology has developed genetically engineered plants with disease resistance. By inserting genes that code for viral coat proteins into a host cultivar, plants have been shown to have immunity to certain viral pathogens. Consequently, a variety of constructs are needed to provide resistance against a broad spectrum of viral diseases since one type of coat protein will only provide resistance to one virus or very close relatives. Fungal diseases, such as rust, mildew, and wilts, have been difficult to combat in the past. Transgenic plants carrying genes for chitinases or glucanases have been produced, which can break down chitins and carbohydrates found in fungal cell walls. This method has been introduced into tobacco, corn, potato, lettuce, squash, melon, and petunias.

Other transgenic traits of value

There are a handful of other genetically engineered cultivars out that have helped with environmental stress tolerance or improved product quality. Some genes have been found to increase cold tolerance or drought tolerance in plants that suffer physiological stress from these factors. In addition, plants have been produced that provide better tasting or better looking product, products with increase shelf lives, altered nutritional value, or easier harvesting methods. Some transgenic plants may even be used to produce pharmaceuticals and marketable compounds.


How are GM crops produced?

            All the properties of a living entity are encoded in its DNA, which is contained in the nuclei of its cells. The DNA is a long, double-stranded molecule with its constituents arranged in a particular order. Segments of this DNA, called genes, perform specific functions like making a protein or regulating a chemical process.

A GM crop is produced principally by introducing a gene sourced from any foreign organism that does not naturally hybridize with the crop species being genetically engineered. The foreign gene can also synthesized DNA sequence for a product and the receiving crop is known either not to produce it, or produce it in insufficient quantity. The introduced gene also includes elements such as promoters, termination sequences and some times selection markers, all of which are required for making the gene express the protein it codes for and enables the its detection in the process of genetic transformation. The whole composition is known as a “gene construct or transgene”. The GM plant is produced either by the direct transfer of transgene into its genome through ballistic bombardment or through a bacterium Agrobaterium tumefaciens (commonly referred to as Nature’s Genetic Engineer) which has the capacity to transfer the gene construct into the recipient plant through infection. For example, Bacillus thuringiensis, a naturally occurring bacterium has a gene that directs the production of crystal proteins which is toxic to certain larvae (bugs). These bugs called bollworms and fruit & shoot borers are the main destroyers of cotton, brinjal and a variety of crops. This gene was taken out of the bacteria and introduced into the cotton or brinjal plant's DNA. This genetically modified cell is allowed to grow into a plant and its seeds contain the code for pest resistance. When bollworms start eating plants grown from these seeds they die, saving the crop. Similar changes can make a plant resistant to weedicides so that spraying doesn't damage the crop even as weeds are killed. All kinds of other changes have been tried including making sweet potatoes more sweet, increasing vitamin A in rice and so on.


Global status of commercialized GM Crops

Since the introduction of the first GM seeds in 1996, their use has spread to 25 countries in the world, covering about 141 million hectares (mha: see Table below) of land - about 9 per cent of the world's 1.5 billion hectares of total cultivated land. More than half of the GM crop area is under herbicide-tolerant soybean (67.8 mha) and a quarter is under various types of maize (35.6 mha). Bt cotton (15 mha) and canola (7 mha) are the other major GM crops in use.

Most of the countries in North and South America use GM crops, mainly soybean, maize, canola and sugar-beet. Over half of the world's total area under GM crops is in the United States. In Europe, only seven countries have allowed GM crops. The EU has imposed a ban on their unregulated cultivation. In Africa, only three countries use GM crops. In Asia, too, three countries including India and China have allowed certain GM crops but under tightly-regulated conditions.

In India, about 9.2 million mha is under GM crops, mostly under Bt cotton. Bt cotton in India has revolutionized cotton production in the country with 5.8 million farmers planting 9.2 million hectares in 2009, equivalent to a record 89% adoption rate.


Global area of GM crops: By Country (October, 2010)



Area (mh)

GM Crops




Soybean, Maize, Cotton, Canola, Squash, Papaya, Alfalfa, Sugarbeet




Soybean, Maize, Cotton




Soybean, Maize, Cotton








Canola, Soybean, Maize, Sugarbeet




Cotton, Tomato, Popular, Papaya, Sweet Pepper






South Africa


Soybean, Maize, Cotton




Soybean, Maize












Cotton, Canola








Soybean, Cotton


Burkina Faso










Soybean, Maize, Canola






Czech Republic
















Costa Rica


Cotton, Soybean










mh: Million Hectares


GM Foods and the properties of the genetically modified variety


Properties of the genetically modified variety



Resistant to glyphosate or glufosinate herbicides

Herbicide resistant gene taken from bacteria inserted into soybean

Corn, field

Resistant to glyphosate or glufosinate herbicides. Insect resistance via producing Bt proteins, some previously used as pesticides in organic crop production. Vitamin-enriched corn derived from South African white corn variety M37W has bright orange kernels, with 169x increase in beta carotene, 6x the vitamin C and 2x folate.

New genes, some from the bacterium Bacillus thuringiensis, added/transferred into plant genome.

Cotton (cottonseed oil)

Pest-resistant cotton

Bt crystal protein gene added/transferred into plant genome


Resistant to glyphosate or glufosinate herbicides

New genes added/transferred into plant genome.

Hawaiian papaya

Variety is resistant to the papaya ringspot virus.

New gene added/transferred into plant genome


Variety in which the production of the enzyme polygalacturonase (PG) is suppressed, retarding fruit softening after harvesting.

A reverse copy (an antisense gene) of the gene responsible for the production of PG enzyme added into plant genome

Rapeseed (Canola)

Resistance to herbicides (glyphosate or glufosinate), high laurate canola

New genes added/transferred into plant genome

Sugar cane

Resistance to certain pesticides, high sucrose content.

New genes added/transferred into plant genome

Sugar beet

Resistance to glyphosate, glufosinate herbicides

New genes added/transferred into plant genome


Genetically modified to contain high amounts of Vitamin A (beta-carotene)

"Golden rice" Three new genes implanted: two from daffodils and the third from a bacterium

Squash (Zucchini)

Resistance to watermelon, cucumber and zucchini yellow mosaic viruses

Contains coat protein genes of viruses.

Sweet Peppers

Resistance to virus

Contains coat protein genes of the virus.



What is Bt.?

To prevent the loss (30-70%) in agricultural production by various insect pests we have to use chemical and most of chemicals used so far as insecticides are Priority Pollutants which are mutagenic, carcinogenic, teratogenic and shows suspected or acute toxicity. Moreover, chemical pesticides are recalcitrant, non-biodegradable and are not target specific and also poses serious threat to human health and environment.

Hence, there is an urgent need to reduce the dependence on chemical pesticide by using safer alternatives to manage insect pests.

Bacillus thuringiensis: The most prevalent non-pathogenic borne bacterium in nature which produces Bt crystal proteins (lethal only to insect pests which infects most of our agricultural crops). Bt proteins are packed in the form a crystals and when ingested by the insect pest larvae are processes to an active form in the highly alkaline larvae gut. The active protein binds to a compatible receptor protein present in the gut cell membranes resulting in perforations of the membranes and cell lysis leading to the death of the larvae. No harmful effects have been observed on human beings, other mammals and non-target organisms including beneficial insects due to absence of receptors to Bt proteins.

Bacillus thuringiensis

Three Bt transgenic crops viz. cotton, corn and potato have been already commercialized with substantial benefits to farmers. In a short span of seven years the area under Bt cotton cultivation has increased from 0.02 million hectares to 9.2 million hectares. India is occupying the second position in terms of global cotton production.

The benefits of Bt includes lesser level of pesticide contamination in environment, reduced farmers exposure to toxic priority pollutants and improvement of human health, increase in the populations of beneficial insects, reduced risk for wildlife, reduced fuel and raw material consumption and biopesticides are eco-friendly and cost effective.


Bt crops under development in India

Sr. No.


Organization (s)




TNAU Coimbatore; IVRI Varanasi; UAS, Dharwad; IARI, New Delhi; Sungro Seeds Ltd., New Delhi

Insect resistance/ cry1Ac, cry1Aa and cry1abc



Nunhems India Pvt. Ltd.

Insect resistance/ cry1Ba abd cry1 CA



Sungro Seeds Ltd., New Delhi

Nunhems India Pvt. Ltd

Insect resistance/ cry1Ac, cry1Ba and cry1Ca



Mahyco, Monsanto, Rasi, Nuziveedu, Ankur, JK Seed, CICR, UAS-D

Insect resistance / herbicide tolerance/ cry1Ac



ICRISAT, Hyderabad

Virus resistance / Chitinase gene



Monsanto, Mumbai

Shoot borer/ cry1Ab



ICRISAT, Hyderabad

Insect resistance / Pod borer, cry1Ac



University of Delhi, New Delhi

Hybrid seed, barnase / barstar gene



MAHYCO, Mumbai

Borer cry1Ac, cry12Ab


Pigeon pea


Pod borer and Fungal pathogen, cry1Ac and chitinase



CPRI, Shimla; NIPGR, New Delhi

Ama1 and Rb gene derived from Solanum bulbocastanum



MAHYCO, Mumbai, TNAU, Coimbatore

cry1B- cry1Aa fusion gene, cry1Ac, cry12Ab, Rice chitinase (chi11) or tobacco osmotin gene



NRCS, Hyderabad

Insect resistance, Shoot borer



IARI, New Delhi; MAHYCO, Mumbai; NIPGR, New Delhi

Antisense replicase gene of tomato leaf curl virus, cry1Ac


Misconceptions about GM Crops (Prabhu, 2010)

            There are some mi