With the ever growing population to feed and diminishing land, water and other natural resources, there is great stress on scientists and researchers to develop techniques to improve food and crop production on currently available cultivable land and also develop means to grow them on non cultivable land, to improve food processing and preservation techniques and to improve food quality and nutrition. One of the solutions to this inevitable problem could be the utilization of recent advancement in recombinant technology or biotechnology.
Earlier, if we wanted to improve a breed, or crop we used natural breeding methods. However, the process is slow and there is little or no guarantee of any particular gene combination from the million of crosses generated. Since, genetic modification or genetic engineering techniques allows the direct transfer of one or just a few genes, between either closely or distantly related organisms, the desired results can be achieved more quickly with enhanced efficiency and predictability.
Genetic modification or genetic engineering or bioengineering or recombinant DNA technology or molecular cloning refers to new methods of breeding plants, animals, or microorganisms, by introducing a copy of gene for a specific trait. The genes can be copied from any organism. In fact, genes from one organism to another unrelated organism can be transferred, producing what is now known as “genetically modified organism (GMOs)” or “transgenic animal/plant”. Any food produced this way is called “genetically modified food” or “GM food”. The first GM plant was produced in 1983, using an antibiotic-resistant tobacco plant. Genetically modified microbial enzymes were the first application of GMO in food production and were approved in 1988 by the US Food and Drug Administration. The first GM food approved for release was the Flavr Savr tomato in 1994.
The genetic modification techniques involve various steps such as identification and isolation of desirable gene responsible for desired traits or feature, modification of the parent (original) gene (breakage of DNA, linkage of DNA segment into vector DNA, transformation of recombinant DNA into host plant, addition of promoter and terminator sequence, incorporation of a marker gene), multiplication of implanted gene and expression of traits.
Gene transfer or transformation can be accomplished by using DNA-based or micro-organisms-based (Agrobacterium tumifaciens) or physical methods-based (biolistics: particle bombardment technique using microparticle gun, electroporation, sonication) or chemical methods-based (use of polyethyleneglycol (PEG) or CaCl2 to facilitate the entrance of foreign DNA) techniques.
Every transgenic plant must be verified for the incorporation of the transgene. Assays can be done to determine the activity of the transgene, whether this gene is passed stably from one generation to the next, and whether there are unforeseen effects on plant growth, yield, and quality. If a plant passes these tests, it is rarely directly used for crop production; instead it will be crossed with an improved line of the crop.
Some Examples of GM Foods
1) Flavr Savr tomato - reduced ripening time crops
Commercial sale of GM foods began in 1994, when Calgene first marketed its Flavr Savr delayed-ripening tomatoes (transgene - antisense gene for polygalacturonase). It reduced ripening time and tomatoes remained firm for a long time even after harvesting thus making transportation easier (less use of ethylene gas for ripening) and increased the shelf life of the tomato.
2) Roundup Ready and Liberty Link – herbicide resistant crops
Unwanted weeds are removed using herbicides such as Roundup (chemical name: glyphosate) and Liberty (glufosinate) - broad-spectrum and have the advantage of breaking down easily (transgene - Enolpyruvinylshikimate-3-phosphate synthase, EPSP synthase). Commercial varieties now available are soybean, corn and canola. Coming in the future are sugarbeet, lettuce, strawberry, alfalfa, potato and wheat.
3) Maximizer – insect resistant crops
Insect resistance crops mostly make use of the Cry gene in the bacteria Bacillus thuringiensis (Bt); this gene directs the production of a protein that causes paralysis and death to many insects. Some commercial varieties are Maximizer, Natureguard (transgene - Cry gene)
4) Golden Rice - enhanced nutrient crops
Transgenic technology produced a type of rice that accumulates beta-carotene in rice grains. Once inside the body, beta-carotene is converted to vitamin A (transgene - three pathway enzymes). More than 120 million children in the world suffer from vitamin A deficiency. Golden Rice has the potential to help prevent the 1 to 2 million deaths each year caused by a deficiency of this vitamin.
5) Optimum - modified soybean oil - high oleic acid
The genetic modification of soybean was achieved by sense suppression of gene, which encodes a desaturase enzymes resulting in high (>76%) oleic acid in oil.
6) Recombinant chymosin - enzyme
It made possible availability of pure and cheap recombinant Calf chymosin - Escherichia coli - first genetically modified product approved by FDA in 1990 (transgene - genetically engineered enzyme). Also studies on recombinant Prochymosin - Saccharomyces cerevisiae, Kluyveromyces marxianus var. lactis, Aspergillus niger, Trichoderma reesei have also been done.
7) Processing Aids
GMOs can be used in various processing techniques such as in fermentation process, enhance quality of finished products, use of amylolytic yeast for producing low carbohydrate beer, modified baker’s yeast to speed up leavening process in breads, etc.
8) Edible Vaccines
Vaccine of hepatitis B, a virus responsible for causing chronic liver disease can be engineered in tobacco and potatoes. Also vaccines against E. coli toxin and measles virus have been successfully expressed in plants and delivered orally. There is hope to produce edible vaccines in bananas, which are grown extensively throughout the developing world.
9) Freedom II Squash - virus resistant crops
The Freedom II squash confer resistance to zucchini yellows mosaic virus and watermelon mosaic virus II. Scientists are now trying to develop crops with as many as five virus resistance genes (transgene - virus coat protein).
10) Genetic Modification in Dairy
Genetic engineering can be utilized for modification in milk composition, produce transgenic cow or make GM bovine somatotropin which could increase yield, growth rate, protein to fat ratio (transgene - genetically engineered hormone) or use recombinant coagulating enzyme, recombinant chymosin (transgene - genetically engineered enzyme) or use modified starter cultures such as modified Lactococcus, Lactobacillus and Streptococcus species for manufacture of cheese and yoghurt, develop phage resistant culture or organisms with probiotic activity or production of therapeutic components such as production of human lactalbumin and lactoferrin to make cow milk more like human milk and thus could be an obvious choice for infant formulae and other nutraceutical products.
11) Biodegradable Plastics
Conventionally, plastics polymers are made via petroleum-based processes. Because of the growing concerns over the environmental impact of petroleum-derived polymers, alternative methods to synthesize the polymers are under investigation. Many microorganisms naturally produce polyhydroxyalkanoates (PHAs) in the form of granules that the organisms use as an energy storage material. PHAs are genuine polyester thermoplastics with properties similar to the petroleum-derived polymers. In addition, PHAs are degradable by depolymerase, an enzyme family widely distributed among bacteria and fungi.
Advantages of GM Food
It includes increased yield, reduced maturation time, increased nutritional value, e.g. increased protein content of rice, improved sensory attributes of food, e.g. flavor, texture, resistance to pests and reduced use of pesticides, increased tolerance to adverse growing conditions, e.g. cold/heat/drought, selectively reduced allergy-causing properties of some foods.
Scenario of GM Foods
A report by the International Service for the Acquisition of Agri-biotech Applications (ISAAA) named, ‘Global Status of Commercialized Biotech/GM Crops: 2016’, stated that GM Crop cultivation has touched a new peak showcasing 110-fold increase in adoption rate of GM/biotech crops globally from 1.7 million hectares in 1996 to 185.1 million hectares in 2016. The most planted GM crops in 2016 were soybean, maize, cotton and canola.
India, too, is seen adopting GM crops at a rapid pace. India landed on the fifth spot, with 10.8 million hectares production, while USA remained as top producer of GM crops globally, which planted 72.9 million hectares in 2016. The year, 2016 was the turning point for GM crops in India as it transcended from the shadows of the moratorium on Bt Brinjal imposed in 2010 towards commercial release of GM mustard. India has completed the process of inviting public comments on the biosafety dossier of GM mustard, seeking permission for environmental release of transgenic mustard hybrid DMH-11 and parental lines expressing barnase, barstar and bar genes. These have been developed by the Centre for Genetic Manipulation of Crop Plants (CGMCP) of the University of Delhi. Also, India received approval of field trials of insect resistant (IR) chickpea and IR pigeon pea developed by ICAR-Indian Institute of Pulses Research. India retained the title as the number one cotton producing country in the world with cotton production surpassing 35 million bales despite the slowed down global cotton market. The major states growing IR cotton in 2016 include Maharashtra, Gujarat, Andhra Pradesh and Telangana, Madhya Pradesh, Punjab, Haryana, Rajasthan, Karnataka, Tamil Nadu and Odisha.
Future Prospects and Conclusion
There are various concerns and controversies related to GM Food. However, it is to be noted that they have been used in many countries for decades e.g. United States and to date no adverse health effects have been caused by products approved for sale. Most feeding trials have observed no toxic effects. However, they are still not accepted in many countries like in Europe. Some products failed initial safety testing and were discontinued, due to allergic reactions. Few reports attribute physiological changes to GM food. Greenpeace and World Wildlife Fund consider that the available data inadequate and call for additional and more rigorous testing. Also there are concerns over environmental issues such as evolution of super pests and super weeds, spread of genes from modified plants to unmodified relatives, which might produce species of weeds resistant to herbicides, harm to other organisms, etc.
However, still various GM crops have been commercialized and new innovations are expected in the future. This is manifested by the increasing use of stacked traits, the new generation of GM crops that does not only address farmers’ concerns but also consumers’ preference and nutritional needs, and the amplified use of gene discovery in crop improvement and development of new varieties.
Thus, together with conducive and harmonized regulations, crop biotechnology innovations can help double food production to address the needs of the growing global population, especially those in the developing countries.
Source: www.isaaa.org/resources/publications/briefs/52/download/isaaa-brief-52-2016.pdf, www.isaaa.org/resources/publications/pocketk/16, www.thehindubusinessline.com/economy/agri-business/globally-acreage-under-gm-crops-at-a-new-high-of-1851-m-hectares/article9682984.ece, en.wikipedia.org/wiki/Genetically_modified_food,www.huffingtonpost.com/builtlean/diet-and-nutrition_b_4323937.html