Myths and realities about transgenic foods
Hunger is the biggest crime and to a man with an empty stomach FOOD is God.
Posted by: Dunichand
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 inIndiaalone (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 transgeneic 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
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:
- Producing an enzyme which detoxified the enzyme
- Producing an altered target enzyme which is not affected by the herbicide
- 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)
|Butricil||Cotton, potato, tobacco|
|Phosphoinothiricin||Alfalfa, Arabidopsis, barley, beet, corn, creeping bentgrass, melon, peanut, poplar, rapeseed, rice, soybean, sugar cane, sweet potato, tobacco, tomato, wheat|
|Sulfonylurea||Corn, cotton, grape, rapeseed, tobacco, tomato|
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.
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 andSouth Americause GM crops, mainly soybean, maize, canola and sugar-beet. Over half of the world’s total area under GM crops is in theUnited States. InEurope, only seven countries have allowed GM crops. The EU has imposed a ban on their unregulated cultivation. InAfrica, only three countries use GM crops. In Asia, too, three countries includingIndiaandChinahave allowed certain GM crops but under tightly-regulated conditions.
InIndia, about 9.2 million mha is under GM crops, mostly under Bt cotton. Bt cotton inIndiahas 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)
|Rank||Country||Area (mh)||GM Crops|
|1||USA||67.0||Soybean, Maize, Cotton, Canola, Squash, Papaya, Alfalfa, Sugarbeet|
|2||Brazil||21.9||Soybean, Maize, Cotton|
|3||Argentina||21.8||Soybean, Maize, Cotton|
|5||Canada||8.3||Canola, Soybean, Maize, Sugarbeet|
|6||China||4.1||Cotton, Tomato, Popular, Papaya, Sweet Pepper|
|8||South Africa||2.4||Soybean, Maize, Cotton|
|17||Chile||0.1||Soybean, Maize, Canola|
|23||Costa Rica||0.1||Cotton, Soybean|
mh: Million Hectares
GM Foods and the properties of the genetically modified variety
|Food||Properties of the genetically modified variety||Modification|
|Soybeans||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|
|Alfalfa||Resistant to glyphosate or glufosinate herbicides||New genes added/transferred into plant genome.|
|Hawaiian papaya||Variety is resistant to the papaya ringsport virus.||New gene added/transferred into plant genome|
|Tomatoes||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|
|Rice||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.
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.Indiais 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.||Crop||Organization (s)||Traits/Gene|
|1||Brinjal||TNAU Coimbatore; IVRI Varanasi; UAS, Dharwad; IARI, New Delhi; Sungro Seeds Ltd., New Delhi||Insect resistance/ cry1Ac, cry1Aa and cry1abc|
|2||Cabbage||Nunhems India Pvt. Ltd.||Insect resistance/ cry1Ba abd cry1 CA|
|3||Cauliflower||Sungro Seeds Ltd.,New Delhi
Nunhems India Pvt. Ltd
|Insect resistance/ cry1Ac, cry1Ba and cry1Ca|
|4||Cotton||Mahyco, Monsanto, Rasi, Nuziveedu, Ankur, JK Seed, CICR, UAS-D||Insect resistance / herbicide tolerance/ cry1Ac|
|5||Groundnut||ICRISAT,Hyderabad||Virus resistance / Chitinase gene|
|6||Maize||Monsanto, Mumbai||Shoot borer/ cry1Ab|
|7||Chickpea||ICRISAT,Hyderabad||Insect resistance / Pod borer, cry1Ac|
|8||Mustard||UniversityofDelhi,New Delhi||Hybrid seed, barnase / barstar gene|
|9||Okra||MAHYCO, Mumbai||Borer cry1Ac, cry12Ab|
|10||Pigeon pea||ICRISAT, MAHYCO||Pod borer and Fungal pathogen, cry1Ac and chitinase|
|11||Potato||CPRI, Shimla; NIPGR,New Delhi||Ama1 and Rb gene derived from Solanum bulbocastanum|
|12||Rice||MAHYCO, Mumbai, TNAU,Coimbatore||cry1B- cry1Aa fusion gene, cry1Ac, cry12Ab, Rice chitinase (chi11) or tobacco osmotin gene|
|13||Sorghum||NRCS,Hyderabad||Insect resistance, Shoot borer|
|14||Tomato||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 misconceptions about GM Crops general public as under:
1. GM Crops are unsafe and harmful: The most common misconception is that GM Crops very unsafe to grow and also GM Foods are very unsafe to consume and harmful for human beings, animals and environment. It needs to be understood that GM crops and Foods are rigorously evaluated and analyzed for any risk they may pose to human beings, animals and environment. Only when it is confirmed safe through a standard set of investigations and protocols, a GM crop is released in environment for cultivation.
2. GM crops destroy natural genetic diversity: Gene transfer from crops to other plants is now called “gene flow”: The environmental concern is about the inserted gene “going wild”, that is, getting transferred to other plants in nature.
It is often stated that GM crops erode natural genetic diversity of the crop. This myth is based on the ability of the GM crops themselves to become invasive or pass the invasiveness to wild relatives or native varieties through “gene flow”. While it may so happen that a highly successful GM variety may get so popular that it may end up replacing other varieties like many traditional varieties have done in the course history, it does not mean that this will cause erosion of genetic diversity. It only ends up into the pattern of “monoculture” as may also happen in the case of a popular single non-GM variety for a crop. However this not likely to happen in India where large number of private and public plant breeders and seed producers invariably keep developing and releasing GM, or non-GM varieties. Moreover there are no possibilities of a gene like insect resistance, salt tolerance or disease resistance enabling a GM crop to be invasive, or spread into varieties in the wild.
As such, inIndia, multiple crops are grown each year in almost all parts and there are wild relatives of few crops which occupy large areas. Even if herbicide tolerance genes are developed and they do move into wild types, these plants are not provided with extra fitness for them to produce more seeds. It makes the variety of wild relative possibly gain herbicide tolerance, only to the targeted herbicide. Neither it becomes fitter nor invasive by producing more seeds than usual.
3. GM crops contains foreign bacterial or animal genes: Even if the transgene is taken out from a bacterium, animal or other plant species, the GM plant does not becomes a bacterium, animal or another plant species. It only produces the protein and not the tissue or organ that belongs to the source organism. There are thousands of genes that are common between crops and animals and the transgene is only a chemical entity made up of common components existing in human beings and plants or bacteria.
4. GM crops increase yield and reduce soil fertility: No GM crops has any additional yielding ability over and above its original traditional counterpart variety or hybrid. If the transgene makes the GM crop resistant to diseases, pests and draught and heat stresses, it helps to achieve its full productivity potential without any yield loss due to the stresses. Thus, the GM crop variety or hybrid only responds to the genetic potential of the non-GM traditional counterpart and does not reduce soil fertility additionally. Unless the transgene itself is for yield increase, the GM crop does not yield more than the yield potential of the original crop variety.
Role of molecular methods in plant improvement:
- Insect resistant plants
- Herbicide-tolerant plants
- Virus resistant plants
- Vitamin A- and iron-enriched rice (Swiss Federal Institute of Technology for Plant Sciences have created a strain of “golden rice” containing an unusually high content of beta-carotene (vitamin A)
- Nutritionally enhanced crops
- Anti-cancer substances
- Edible vaccines
- Antibodies from plants
- Biodegradable plastics
- New biomaterials
- Disease-resistant plants
- Cold tolerance
- Spoilage-resistant seeds and tubers
- Stress-resistant crops (Drought/salinity tolerance)
- High-yielding cereals e.g. rice
- Phytoremediation (Popular trees)
Possible benefits of GM Foods
The world population is predicted to 14 billions in the next 50 years and ensuring an adequate food supply for this booming population is going to be a major challenge in the years to come. GM foods promise to meet this need in a number of ways:
1. Pest resistance Crop losses from insect pests can be staggering, resulting in devastating financial loss for farmers and starvation in developing countries. Farmers typically use many tons of chemical pesticides annually. Consumers do not wish to eat food that has been treated with pesticides because of potential health hazards, and run-off of agricultural wastes from excessive use of pesticides and fertilizers can poison the water supply and cause harm to the environment. Growing GM foods such as B.t. corn can help eliminate the application of chemical pesticides and reduce the cost of bringing a crop to market.
2. Herbicide tolerance For some crops, it is not cost-effective to remove weeds by physical means such as tilling, so farmers will often spray large quantities of different herbicides (weed-killer) to destroy weeds, a time-consuming and expensive process, which requires care so that the herbicide doesn’t harm the crop plant or the environment. Crop plants genetically-engineered to be resistant to one very powerful herbicide could help prevent environmental damage by reducing the amount of herbicides needed. For example, Monsanto has created a strain of soybeans genetically modified to be not affected by their herbicide product Roundup®. A farmer grows these soybeans which then only require one application of weed-killer instead of multiple applications, reducing production cost and limiting the dangers of agricultural waste run-off.
3. Disease resistance There are many viruses, fungi and bacteria that cause plant diseases. Plant biologists are working to create plants with genetically-engineered resistance to these diseases.
4. Cold tolerance Unexpected frost can destroy sensitive seedlings. An antifreeze gene from cold water fish has been introduced into plants such as tobacco and potato. With this antifreeze gene, these plants are able to tolerate cold temperatures that normally would kill unmodified seedlings.
5. Drought tolerance/salinity tolerance As the world population grows and more land is utilized for housing instead of food production, farmers will need to grow crops in locations previously unsuited for plant cultivation. Creating plants that can withstand long periods of drought or high salt content in soil and groundwater will help people to grow crops in formerly inhospitable places.
6. Nutrition Malnutrition is common in third world countries where impoverished peoples rely on a single crop such as rice for the main staple of their diet. However, rice does not contain adequate amounts of all necessary nutrients to prevent malnutrition. If rice could be genetically engineered to contain additional vitamins and minerals, nutrient deficiencies could be alleviated. For example, blindness due to vitamin A deficiency is a common problem in third world countries. Researchers at the Swiss Federal Institute of Technology Institute for Plant Sciences have created a strain of “golden” rice containing an unusually high content of beta-carotene (vitamin A). Since this rice was funded by the Rockefeller Foundation, a non-profit organization, the Institute hopes to offer the golden rice seed free to any third world country that requests it.
7. Pharmaceuticals Medicines and vaccines often are costly to produce and sometimes require special storage conditions not readily available in third world countries. Researchers are working to develop edible vaccines in tomatoes and potatoes. These vaccines will be much easier to ship, store and administer than traditional injectable vaccines.
8. Phytoremediation Not all GM plants are grown as crops. Soil and groundwater pollution continues to be a problem in all parts of the world. Plants such as poplar trees have been genetically engineered to clean up heavy metal pollution from contaminated soil.
Genetically modified food in your supermarket?
Most supermarket processed food items now test positive for the presence of genetically modified ingredients. In addition, several dozen more genetically engineered crops are in the final stages of development and will soon be released into the environment and sold in the marketplace. According to the biotechnology industry, the majority of food and fiber will be genetically engineered within the next 5 to 10 years.
The most widely grown genetically engineered crops, accounting for over 90% of all the genetically engineered crop acreage in America, are corn, cotton, soy and canola. Potatoes and tomatoes in processed foods may also come from genetically engineered seed.
Genetically-modified foods have the potential to solve many of the world’s hunger and malnutrition problems, and to help protect and preserve the environment by increasing yield and reducing reliance upon chemical pesticides and herbicides. Yet there are many challenges ahead for governments, especially in the areas of safety testing, regulation, international policy and food labeling. Many people feel that genetic engineering is the inevitable wave of the future and that we cannot afford to ignore a technology that has such enormous potential benefits. However, we must proceed with caution to avoid causing unintended harm to human health and the environment as a result of our enthusiasm for this powerful technology.
Nothing has driven more species to extinction or caused more instability in the world’s ecological systems than the development of agriculture sufficient to feed 6.5 billion people. To assert that GM techniques are a threat to biodiversity is to state the exact opposite of the truth. The less focused and productive this agriculture is, the more destructive its effects will be.
Hence, farming must fully embrace genetically modified (GM) crops to meet the dual challenges of population growth and global warming in the 21st century.