V. Nagesh Babu Pendem
National Institute of Miners’ Health (NIMH)
JNARDDC Campus, Amarawati Road, Wadi
Nagpur-440023, State of Maharashtra, The Indian Union (INDIA)
Tel: 07104-224121, 224494, 224495, Fax: 07104-224121
The world population* is growing at an alarming rate and consequently the demands of the population. The challenge of future global food security can be met by increasing food production on the same or existing available land. Biotechnology steps in at this juncture in the form of Genetically Modified Foods (GMF) to overcome the demand of food production, processing and safety. Dr. Norman Borlaug, Nobel laureate (1970) and father of green revolution noted that “Biotechnology is a new revolution providing feed, food and industrial products to support a global population increasing at the rate of 100 million per year”.
Genetic Engineering/Biotechnology can be defined as “manipulation of plant/animal/microbial genomes via introduction of a characterized DNA segment”. The basic principle of genetic engineering is that genetic material (DNA) can be transferred from a cell of one species to another unrelated species and made to express itself in the recipient cells. This technique is also commonly known as “Recombinant DNA Technology” used to develop new plant/animal varieties known as Transgenic plants/Transgenic animals.
The tools of Biotechnology/Genetic Engineering can be used to improve texture, colour, flavour, growing season, stress tolerance, yield , geographic distribution, disease resistance, shelf life etc.,
Steps in Genetic Engineering:
1) Isolation of gene of interest
2) Cloning with Bacterial DNA
3) Multiplication of Bacterial Recombinant DNA
4) Introduction of Recombinant DNA into plant/animal/microorganisms
5) Selection of seedlings synthesizing the introduced gene trait
Results of Genetic Engineering in Plants:
a) Higher crop yields
b) Improved resistance to diseases
c) Improved resistances to drought, frost, temp.
d) Altered product composition (oil/fat/protein)
e) Delayed ripening of fruit
f) Removal of undesired components
g) Introduction of new genes (ex. Nitrogen fixing system)
Advantages of Genetically Modified Foods:
There are number of reasons why GM technology is preferred to traditional breeding techniques. Not only it is much faster but also allows greater precision in selecting desirable characteristics. During the past 15-20 years the new genetic engineering approach improved the following aspects.
i) Pest resistance:
A gene that naturally occurring in the soil bacterium, Bacillus thuringiensis (Bt) produces an insecticidal protein which interferes with the ion transport system disrupting an insect ability to feed. Plants carrying an inserted Bt gene are able to produce the Bt protein, protecting themselves against certain targeted pests.
ii) Herbicide tolerance:
Approximately one third of all biotechnologically developed plant products approved under regulatory review, prior to commercial use are tolerant to broad spectrum of herbicide. These new crops provide farmers greater flexibility in herbicide use and reduce (or) eliminate the need for pre emergent soil application.
iii) Virus resistance:
Plant viruses cause major losses in the yield and adversely affect the crop quality. By using genetic engineering technology virus resistant plants may be produced. China was the first country to commercialize virus resistance transgenic crops with the introduction of virus resistant tobacco in 1992.
iv) Controlled ripening:
The enzyme, 1-amino cyclopropane 1-carboxylase synthase is responsible for ethylene synthesis, which in turn causes ripening in Tomatoes. By using genetic engineering technology sense copies of this gene can be introduced by transformation that results in the failure of the above resident gene so that there will be a controlled ripening in tomatoes.
v) Nutritional improvement:
By using GM technology, attempts to incorporate special oils, carbohydrates, proteins and other value added ingredients into common crops have also been carried out with a mixture of success.
vi) Adaptation to harsh growing conditions:
Plants produced by genetic engineering technology are expected to adapt for harsh growing conditions such as drought, temperature extremes and soils with high salt content.
vii) Phytase production:
By using GM technology, a gene from bacterium, Aspergillus niger encoding for phytase enzyme was introduced in crops. The phytase added to soil increases the bioavailability of phosphorous to the plant roots. Phytase, an effective chelator of divalent cations like Zn+2 and Fe+2, causes decrease mineral availability to plants. With the application of genetic engineering technology, Phytate level can be reduced with the help of Phytase in soybean and other vegetable products that may play a role in human nutrition.
viii) Edible vaccines (Antigen expression):
Researchers have already shown by using GM technology, that it is possible to insert certain genes encoding for Hepatitis, Chlorella into certain crops there by the inserted genes expresses the proteins that are antigenically similar to human serum.
Meson et al (1992) showed that tobacco that was transformed with a gene encoding Hepatitis B surface antigen expresses this proteins in leaves in a from that was antigenically similar to human serum. In the same way Chlorella toxin B subunit (CTB) was introduced in potatoes and it was found that transgenic food plants have the ability to generate protective immunity.
ix) Hypo allergenic rice:
Rice grains contain a 16 KD globulin protein which caused Ectopic Dermatitis in sensitive Japanese children. By GM technology this allergen had been characterized and the gene that encodes for the said protein was sequenced. So it is theoretically possible to produce Transgenic rice with an anti sense gene or a co suppressing construct that would be hypoallergenic (Ijuumi et al 1992).
ix) Genetically improved oils:
Genetic modification of oil seeds (Geeta Sehgal and GS Chauhan, 2000) resulted in high oleic acid, low linolenic acid, increased lauric acid content in oils that helps in human nutrition.
Disadvantages (Risks) of Genetically Modified Foods
There have been various concerns highlighted in recent years regarding the safety of Genetically Modified Foods (GMF). The main concerns include antibiotic resistance, allergenicity, environmental issues etc.
i) Antibiotic resistance:
All genetically engineered products have antibiotic marker genes. Once GM food is absorbed into the human digestive tract, these antibiotic marker genes could move into blood stream or the bacteria of intestines. Such transfers might alter our health directly or change beneficial symbiosis (between intestinal bacteria and human beings). This might further cause spur resistance to antibiotic pharmaceuticals.
Another concern over human consumption of GMFs is that some percentage of the public may be allergic to a protein coded by the gene introduced into GMF. Allergic reactions can be extremely mild or deadly. Exposure to new foods can reveal new allergies and the combination of genetic material can lead to ‘cross allergenicity’, where people allergic to one thing may be allergic to genetic material that has been added to an item, which once they have eaten safely. Therefore the possibility of introducing or amplifying the allergenicity of food by gene transfer is of serious concern. Research by US Company, Pioneer Hi-Bred demonstrated that the allergenicity associated with Brazil nuts was transferable to soybeans. This was achieved during an attempt to increase the level of sulphur rich amino acid, Methionine in soybeans using gene transfer. The soybean was intended for animal feed but as a result of these findings and associated difficulties of preventing them from entering human food chain, the project was discontinued (Noodle et al, 1996). This example demonstrates that a known allergen can be transferred from one source to another, but there is no evidence suggesting that GM Foods are any more or less toxic than traditional foods.
Although antibiotic resistance and allergenicity are serious concerns of Genetically Modified Foods, the other issues like Environmental effects (Biodiversity, alteration of soil microbial flora, herbicide tolerant foods), Economic issues (high investment, monopoly of multinationals), social religious and ethical issues (labor displacement, introduction of animal genes into plants, e.g., fish protein genes into tomato) have to be considered very seriously.
Acknowledgements: The author is thankful to Dr. S. K. Dave, Director, NIMH for his kind permission to publish this article.
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2) Andrew Tingey, International Food Ingredients No:3 1999.
3) Britt E. Erickson –Analytical Chemistry, July1, 2000 (455-459A)
4) Dean Della Penna-Science, July 1999, Vol. 285
5) Geeta Sehgal and GS Chauhan, Genetically Modified Foods-Biotechnological achievement-Indian food Industry-Jan-Feb, 2000 Vol. 19(1)
6) H.C. Sharma and Rodomino Ortiz-Current Science, Vol.79, No.4 125 Aug 2000, 421-436.
7) John Hodgson-Nature Biotechnology, Sep 2000 Vol.18
8) Norman Borlaug-JADA supplement, fall 2000.
9) Pedro A. Prieto etal-J. Nutritional Biochemistry, 1999, 682-695.
10) Dr. P. Suresh-Safety evaluation of GM foods-Preclinical Toxicology workshop at NIN, Hyderabad.
11) Samuel B. Lehren. W.Elliot Horner and Gerald Reese-Critical Reviews in FoodScience
12) Special article edited in Food Digest 2000(23), July-Sep 2000
* Although the population growth seems alarming even today when you look at the population clock, annual world population growth reached its peak in 1960s to around 2% and started to decline. The estimated growth in 2003 is only 1.16%. It is estimated that it declines further to reach 0.43% in 2049 (see Total Midyear Population for the World: 1950-2050). As a matter of fact, the decline in population growth will be a matter of serious concern soon, as the large aging population lives longer without enough support from youth.
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