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Sci Tech
Why so hot on Bt cotton?
THE GENETIC engineering Advisory Committee (GEAC) of the Government has at long last approved the marketing of Bt cotton in the country. With this step, India has made a tentative entry into the age of agricultural biotechnology in a significant way. The entry has not met with any rousing rounds of applause, but then which step of the Government in the recent past has? What are the issues involved?
From Green Revolution to Gene Revolution
The gene revolution that was ushered in the 1970's has turned traditional crop practice on its head. One no longer needs to select, breed and propagate the desired character (high yield, dwarf size) over a period of years, as was done to usher in the Green Revolution. It is easy now to identify the gene that imparts the desired trait (drought tolerance, pest resistance) and insert it into the plant. More often than not, this gene comes from elsewhere, so that its insertion or transfer is from one organism to another. Such gene transfer is done in the lab in a matter of weeks, the effect on the plant monitored and confirmed and, once satisfied, the so genetically modified (GM) plant or its seeds is made available to the farmer. This is a short- cut and sure-fire way over the classical selective breeding technology.
This is what has happened with Bt cotton. In the soil of Thuringea in South East Germany, scientists found in the year 1929 a bacterium, which defends itself valiantly against insects - butterflies, moths and mosquitoes. This microbe, called Bacterium thuringiensis or Bt, contains a protein called the Bt toxin. When the foraging insect eats Bt, the bacterial toxin paralyses the gut of the insect and causes it to die of starvation and tissue damage. Once this special property of Bt was discovered, scientists began culturing it in large quantities, store it as a dry mass and use it to wipe out mosquito larvae in water pools. Then in the early 1980s, scientists analysed the genetic endowment of Bt, and isolated the gene that instructs the bacterium to make the toxin protein. From there to cut this gene from Bt and paste to a plant like corn was but natural; the transgenic plant now not only makes its repertoire of proteins but also the Bt toxin. A pest that lands on this corn plant to feast on it, also gets its fill of Bt toxin and suffers the consequences.
The advantage to the farmer is clear. He no longer has to douse the plantation with loads of chemical pesticides, which are known to be toxic and unsafe for human health. Unlike these, which affect all life forms as a crude bludgeon, Bt toxin is remarkably selective - it affects only insects.
It is not toxic to animals because their digestive systems are fundamentally different from those of insects. The digestive system of most animals, particularly mammals (including humans), includes a stomach that has a strongly acidic juice. Most proteins, including Bt toxin, lose their structural architecture or shape under this condition, and therefore their function or biological activity as well. This is why the Bt toxin cannot affect us the way it does an insect.
It is with this idea that the Bt gene has been introduced into plants such as cotton, potato, corn and soybean. The effect is that the amount of chemical pesticides to be applied on them is dramatically reduced to very low levels. The result is two fold - higher yield (the loss due to the pest is saved) and safer produce (little pesticide residue).
One would thus have expected that the Bt technology would have been greeted with open arms. Indeed this has happened in the US, Argentina and China. Between 1990 and now, the area across the world growing GM crops has shot up from a few acres to over 100 million acres. We in India have now opened the doors to this exciting and useful technology. Yet, the approval by the GEAC for Bt cotton has been greeted with mixed response. Why is this?
Affect the neighbour
Criticism of transgenic or GM crops has come about based on three major scientific concerns. The first is `contamination'of the neighbour. When you plant a field of GM crop right next to a field of its unmodified or traditional relative, chances are that pollen from the former can be carried across by wind or by insects to the latter. When this occurs, the traditional plant can become genetically modified in course of time, Of course, GM crops are of course not the only culprits of such contamination. If you were to plant a selectively- bred high-yield dwarf variety next to a traditional cousin, contamination can occur in exactly the same manner. One way out of this is to keep a safe distance between the two plantations; some say this cordon could be about 100 feet while others think it should be larger so that airborne pollen contamination can be reduced or avoided.
But such a luxury is possible only in very large acreage farms. Small landholdings, common in India, simply cannot afford this. One way out is for farmers to get together and plan their GM cropping on a cooperative basis, just as dairy farmers have done and brought forth the White Revolution.
At the scientific level, this problem is being addressed by some through a different strategy. Do not put in the desired gene in the plant in a manner that it can be spread by pollen. Instead, confine the gene in compartments such as the choloroplast, which are not carried by the wind or insects.
It is clear that such a confinement mode is important and welcome. In other words - go back to the lab for new strategies.
The problem can be solved, and work is already on in several labs on this score.
Bt resistant super-pests?
The second criticism has to do with the point that as Bt toxin is introduced, killing off pests, there will arise in course of time mutant varieties of pests that are tolerant or resistant to the toxin. Being unaffected by Bt, they will merrily chomp off the GM plant and grow in numbers. In other words, in having attempted to overcome the pest we actually start breeding superpests. This is a repeat run of what has been seen with antibiotic drugs or some chemical pesticides, which have actually generated superbugs. As it turns out this is a survival game played in the arena of nature - regardless of whether we follow traditional practices or GM - and needs to be addressed through clever strategies of science. Basic research is of importance here, just as it is in the case of traditional antibiotics.
Allergy to an occasional eater?
The recent review by Drs. D.E. Beeven and C.F. Kemp in Nutrition Abstracts and Reviews Series B: Livestock Feeds and Feeding concludes: "Additionally there is a growing body of scientifically valid information available that indicates no significant risk associated with the consumption of DNA or the the resulting proteins from the GM crops that are registered in any of these countries. Based on the safety analyses required for each crop, consumption of milk, meat and eggs produced from animals fed GM crops should be considered as safe as traditional practices". Yet, there can be allergenic reactions that some humans may suffer from, if they were to take GM crops directly or through the animals fed on them. This possibility cannot be dismissed, since humans (and animals) occasionally do display allergies to foreign proteins and biological material. The frequency of such reactions is, however, low-perhaps one in several hundred thousand individuals. But this is no consolation to that one individual who does suffer. What then should be done? If the material obtained form a GM organism is so labelled, it would offer the choice of use to the susceptible individual. As expected, this is an issue that is contested by the companies that produce and market GM materials, with arguments that are far from convincing. We need to ignore them and insist on a national policy of labelling GM food and crops so that the choice of use is left to the user.
The politics of it
In the final analysis, a major part of the objection to GM crops and food comes not from the above three issues, which are answerable and can be taken care of, but from a sociological or ideological angle. It turns out that agriculture has, over the last three generations or so, moved from being a family affair into an industry. Since the time of the hybrid seeds, industry has captured the steering wheel, promoting the purchase of seeds, fertilizers, pesticides and so forth, buying out small farms, small scale dealers, and acquiring and merging one another.
When the biotechnology door opened, chemical companies such as Monsanto, Dupont, ICI, Bayer and BASF jumped into the fray. They invested largely into research in GM, merged and remorphed themselves to an extent that their names changed by the year - ICI split to Zeneca, then Astra Zeneca, and after a merger with Novartis (itself born out of Ciba, Geigy and Sandoz) to become Syngenta. Today, the entire GM crop and food market around the world is in hands of less than 10 companies. Agriculture has remorphed into Agribusiness. It is this aspect that worries people. Appropriate national strategies to counter it will be needed, and not a day too soon. With arable land dwindling and the population exploding, we have no alternative but to turn to GM crops for food security. Wisdom lies in understanding what the costs and the benefits are, and minimising the former while maximising the latter. That way bathwater is thrown out and the baby kept so the future is secure.
D. Balasubramanian
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