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Biotechnology and Society---Part
20
Genetically-modified crops
Many ideas grow better when transplanted into another mind than in the one they sprung up. - Oliver Wendell Holmes Jr. (1841-1935), US Supreme Court Justice
We mentioned in the previous article how life-saving
therapeutic drugs can be manufactured in transgenic plants. Transgenic plants are not limited to making pharmaceuticals alone. They can be manipulated to increase yield in food crops, make better quality food crops, increase yield in cash crops and avoid plant diseases. All of these measures can be economically advantageous as well as start a new revolution superior to the ‘Green Revolution’ of the last century. Before anyone thinks of transgenic plants as some Frankenstein monsters, it must be mentioned that they are the same as the original from which they were modified except that they contain one or two new desirable traits very similar to conventional breeding and in many ways the process is better and quicker.
Food crops: Plant breeding by conventional means involved selection of seeds from the best plants for replanting the following season. This selection process changed the genetic make-up of the plants creating permanent improvements that are desired in plants. Agronomics, the science of combining agriculture with plant management and economics, was used to predict which parent plants possessed the best traits to produce high yields.
However, the environment on plant performance is also a major factor. A genetically superior plant growing under not-so-ideal conditions is likely to produce inferior results because genetics typically determine only about 20 per cent of a plant’s yield performance while the environment determines the rest. Biotechnology, in conjunction with genomics and
bioinformatics, is speeding up the identification of genes that control valuable traits which help the commercial potential of agricultural biotechnology. Let us look at some of the recent developments in food crops.
 Corn
and soybeans: The damage caused to crops by insects is significant. The insect known as corn borer causes the maximum damage to corn in many countries. It was known that the bacterium,
Bacillus thuringiensis, makes a protein which when ingested by the corn borer, makes it sick and eventually die. The early application of this biopesticide was to spray the product on corn plants during the time the insects are active. But this procedure involved repetitive activity year after year. Monsanto Corporation isolated the gene for the protein and incorporated it into the corn seed which when planted protected itself against the corn borer. It was called Bt corn. The trade name for the seed is YieldGard. It is claimed that YieldGard gene is active in all parts of the corn plant and a two-to-three bushels per acre yield advantage has been noticed over the same hybrid without the new gene.
Next only to insect damage, weeds also cause damage to food crops yield by competing for the soil nutrient resources.
Roundup, is an herbicide developed by Monsanto to curtail weed growth in corn fields. However, in order to minimise the damage by Roundup to corn, the company developed a Roundup Ready Corn. This process involved inserting a gene whose product will neutralise the chemical (glyphosate) in the herbicide used. There has been some concern among the critics of the company that this new seed development was a ruse to increase the use of their herbicide by the farmers. We will discuss this and other environmental issues in the next article.
Soybeans are another vital crop which has been genetically modified to be resistant to the herbicide Roundup. The herbicide-resistant variety was planted on over 59 million acres of land worldwide in 1999 and its usage is growing every year. The growers cited better weed control for less money and lower herbicide costs as important benefits.
Research efforts also continue to focus on ways to improve soybean varieties for yield, disease and insect resistance. Work is also continuing on developing disease-resistant wheat and rice. While more countries are approving these genetically-modified crops for usage, there is also some resistance, especially in Europe.
 Golden rice: The Rockefeller Foundation is helping a project to develop a “golden rice” which would be of immense benefit to developing nations. The project involves the development of vitamin A - and iron-enriched rice species spearheaded by Ingo Potrykus and his team at the Swiss Federal Institute of Technology. The team is transferring a ferritin (iron storage protein) gene into rice and another gene to introduce phytase, an enzyme that will facilitate breakdown of phytate (an organic phosphate) for better utilisation of the mineral. In addition, a gene for cysteine-rich metalloprotein from A. Oryza is also being transferred. The transgenic rice thus created has a two-fold increase in iron, a 25 per cent increase in cysteine content, and high phytase activity. The genes to produce provitamin A are also being transferred from the daffodil plant into another rice species.
The increased provitamin A content would provide the necessary daily dose of vitamin A in a typical Asian rice diet. The crossing of the two species should contain all the essential nutrients in one species.
 Cash crops: Among non-food crops, cotton and tobacco have gained the most attention. Cotton plant is attacked by an insect called boll weevil causing extensive damage to the yield. Bollgard cotton, a genetically-modified variety developed by Monsanto, has been quite successful in containing the insect damage. The usage of the Bollgard seed has resulted in an average yield increase of 20 per cent and an average profit advantage of $ 49 per hectare. Next to the United States, India stands to gain most by using the Bollgard cotton. The Indian government was reviewing the application a year ago and it appears the regulatory authorities are looking favourably at the results.
Developing nations produce more than two-thirds of the world’s cotton on which they use chemical insecticides to the tune of $ 1 billion per annum. Use of the insect-resistant cotton would help reduce the chemical usage while correspondingly increasing the yield.
 Tobacco, once a status symbol in the world by virtue of its being rolled inside a paper and puffed up as smoke, is losing its ground steadily all over the world. However, several companies are using the tobacco plant to make therapeutic proteins and also other important nutrients such as lactoferrin and lysozyme (important antibacterial proteins). In addition, some companies are developing technology to produce industrial enzymes such as alpha-amylase (to break down starch) in tobacco. These developments have the dual benefit of helping the tobacco farmers hurt by the reduced consumption of tobacco while developing an alternative, inexpensive source for valuable industrial enzymes.
Some researchers have created a tobacco plant that can detoxify soil contaminated with the explosive trinitrotoluene (TNT). The plant sucks out TNT from the soil and transforms it and traps it within the plant. Similar projects to decontaminate soils from other contaminants are also in progress. The relatively new discipline of phytoremediation - a process to manage the ecosystem contaminated with toxic pollutants - has great potential in the coming years.
A whole variety of plants are ripe targets for genetic modification: tomatoes which can ripen in the plant for a wholesome taste without rotting in the plant, protecting several other plants from various fungal diseases, creating drought-resistant plants so that they can grow in rain-starved areas and developing saline-tolerant plants in regions where the water has high salt content are some of the possibilities awaiting the next biotech revolution.
Some definitions (to lighten up!)
1 phone: 1 million microphones
1 microfiche: 1 millionth of a fish
3.333 tridents (submarine): 1 decadent submarine
1 decoration card: 10 ration cards
1 centipede: 10 millipedes
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