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Some GM questions answered
1st July, 2003
Why are GM crops being grown, how are plants genetically modified, where is it being cultivated, who’s in control and what is being researched and developed?Why is GM grown?
Ninety-nine per cent of commercially grown GM crops have been engineered to exhibit just two traits – herbicide tolerance and insect resistance.
The most common commercial GM crops are those that have been engineered to be tolerant to chemical weedkillers; they are referred to as being herbicide-tolerant (HT). These crops are created by introducing genes from bacteria that either allow plants to tolerate the effects of the weedkiller or which break it down into a non-toxic form. Herbicide tolerance is intended to make weed control easier for the farmer. It encourages the use of so-called broad-spectrum herbicides like glyphosate, which can kill the majority of green plants without damaging the GM crop. HT crops made up 75 per cent of the global area under GM cultivation in 2002.
The second most common GM crops are those that are resistant to insect pests. These make use of a set of insecticidal toxins produced by the soil micro-organism Bacillus thuringiensis (Bt) and which act by binding to the gut of the insect that ingests them. In Bt crops the toxin gene from the bacterium has been inserted into the plant. When an insect pest feeds on the plant, the pest ingests a dose of the toxin and dies. Pest-resistant crops made up 17 per cent of the global GM cultivated area in 2002.
Transgenic Million hectares % crop worldwide of total
HT soya bean 36.5 62
Bt maize 7.7 13
HT canola 3 5
HT maize 2.5 4
Bt cotton 2.4 4
HT cotton 2.2 4
Bt/HT cotton 2.2 4
Bt/HT maize 2.2 4
Total 58.7 100
Source: James C. 200212
1 A biochemical process is used to cut up strings of DNA and select the required genes.
2 The selected genes are then inserted into circular pieces of DNA (known as plasmids) found in bacteria. Because the bacteria reproduce rapidly, thousands of identical copies of the ‘new’ gene are manufactured in a very short time.
3 The ‘new’ gene is then inserted into the DNA of the plant that is to be engineered. Two principal methods are used to insert the gene:
a) a ‘ferry’ or ‘vector’ is made out of a piece of genetic material taken from a virus or a bacterium; this is then used to infect the plant and the new gene is thus ‘smuggled’ into the plant’s DNA; or
b) the genes are coated onto a large number of tiny gold or tungsten pellets, which are then fired with a special gun into a layer of cells taken from the recipient plant; some of these pellets will pass through the nucleus of a cell and deposit their package of genes, which in certain cases will be integrated into the DNA of the plant’s cells.
4 As the success rates for both these methods is extremely low, the scientists have to find out which – if any – of the plant’s cells have taken up the new DNA. So, before a gene is transferred a ‘marker’ gene is attached that is resistant to an antibiotic. The genetically-engineered plant cells are then grown in a medium containing this antibiotic, and the only ones able to survive are those that have taken up the new genes with the antibiotic-resistant marker attached.
5 Finally, a piece of DNA taken from a virus or bacterium (called a ‘promoter’) is inserted with the new gene in order to ‘switch’ the gene on in its new host.
• As it is not possible to transfer genes with any accuracy, gene transfer can disrupt an organism’s tightly controlled network of DNA.
• Promoters often force the new genes to express their traits very aggressively. Not only does this have the potential to influence neighbouring genes, but it can also stimulate plants to produce higher levels of substances that may be harmless at low levels but which can become toxic in higher concentrations. The new gene could, for example, alter chemical reactions within the cell or it could disturb cell functions. This could lead to instability, the creation of new toxins or allergens and changes in nutritional value.
• Current understanding is extremely limited, and any change to the DNA of an organism at any point may well have knock-on effects that are impossible to predict or control.
A tiny sample of unexpected results to date:
• A gene coding for red pigment was taken from a maize plant and transferred into petunia flowers.
Apart from turning red, the flowers also had more leaves and shoots, a higher resistance to fungi and lowered fertility.
• In trials used to assess the safety of herbicide-resistant soya beans made by Monsanto, 36 cows were divided into different groups. For four weeks some were fed GM soya beans, and some were fed ordinary beans. When the data from the trials was examined, it was found that the cows that were fed the normal soya beans produced 1.19 kilograms of milk fat a day; whereas those fed with GM soya produced 1.29 kilograms – an increase of more than 8 per cent. This shows that a genetic change that was only intended to make a soya bean resistant to herbicide had unexplained side effects. No further tests were conducted to explore these changes, and the GM soya beans were passed by regulatory authorities as safe for consumption.
• In a trial of genetically-engineered insect-resistant maize, there was a yield reduction of 27 per cent and significantly lower levels of copper in the leaves, stalks and grain compared to the conventional plants;
• In 1997 Oxford University scientists investigating the metabolism of potatoes unexpectedly found out how to use genetic engineering to increase the vegetable’s starch content. The scientists were working on what
they believed to be quite a different aspect of potato metabolism when they discovered that suppressing the activity of a particular enzyme dramatically affected the levels of starch produced within the potatoes. ‘We were as surprised as anyone,’ said professor Chris Leaver. ‘Nothing in our current understanding of the metabolic pathways of plants would have suggested that our enzyme would have such a profound influence on starch production.’
• A yeast that was genetically engineered for increased fermentation purposes produced a toxin in concentrations 30 times higher than in non-GM strains.
(Adapted from Genetic Engineering, Food and our Environment by Luke Anderson [Green Books, 1999])
The US, Canada, Argentina and China grew 99 per cent of the world’s GM crops in 2002. South Africa and Australia accounted for most of the remaining 1 per cent, while a further 12 countries grew less than 50,000 hectares each (see map). In total, GM crops covered 58 million hectares of the world in 2002; that’s an area two and a half times the size of the UK. The global market value for GM seeds in 2002 was estimated to be $4.25 billion; that’s 13 per cent of the global seed market.
The agricultural biotech industry is dominated by four multinational corporations: Syngenta, Bayer CropScience, Monsanto and DuPont. In 2001 these firms had a combined turnover from seeds and agrochemicals of $21.6 billion.
Company Agrochemical Seeds/biotech Total
sales ($ million) ($ million) sales ($ million)
Syngenta 5,385 938 6,323
Bayer Aventis 6,086 192 6,278
Monsanto 3,505 1,707 5,212
DuPont 1,922 1,920 3,842
BASF 3,114 0 3,114
Dow 2,627 215 2,842
Total 22,639 4,972 27,611
Source: AgriFutura (29), the newsletter of Phillips McDougall AgriService
After a decade of consolidation in the 1990s the pesticide industry has a chemical, seed and technology empire that gives it access to farmers and markets around the world; and that gives farmers far less choice about their seed supplier and their seeds. By linking their chemicals to seeds via GM technologies, corporations have been able to protect and extend their markets for their herbicides and pesticides – many of the patents on which were previously due to expire.
• Six corporations based in the US and Europe controlled 98 per cent of the market for GM crops and 70 per cent of the world’s pesticide market in 2000.
• Six firms own 54 per cent of US plant biotech patents.
• Ten supply 33 per cent of the global seed market; 20 years ago there were thousands of seed companies.
• Ninety-one per cent of all GM crops grown worldwide in 2001 were from Monsanto seeds.
• In Africa just three corporations – Syngenta, Monsanto and DuPont – now dominate the formal sector seed markets.
• In South Africa Monsanto has total control of the market for GM seed, 60 per cent of the hybrid maize market and 90 per cent of the wheat market.
Dozens of new GM crops are being developed or researched. These include crops genetically modified to produce pharmaceuticals. Open-field trials have taken place in California of GM rice containing human genes for drug production. Pharmaceutical wheat, corn and barley are also being developed in the US, France and Canada.
Disease-resistant crops and crops designed to tolerate drought or high salinity are also being researched. The biotech industry also promises nutritionally improved crops such as pro-Vitamin A enhanced rice (called ‘Golden Rice’) and oils that could, for example, lower cholesterol levels.
• It can cost anything from $50m to $300m to develop a GM crop from the laboratory to the market, and can take up to 12 years.
• Most research and development (R&D) in GM agriculture is conducted by the private sector. Six corporations account for almost 65 per cent of the world’s total agricultural biotech R&D; they spent over $1 billion on GM crop R&D in 1998.
• GM crops are planted almost exclusively by large commercial growers in rich and middle-income countries; less than 1 per cent of all GM R&D is estimated to be directed at resource-poor farmers.
GM applications appear to offer hope to the world’s poor and hungry. Yet it is doubtful whether any of these applications will make it into the fields of farmers in the developing world – for two simple reasons:
1 The science of GM is young and complex, and each gene or trait explored in the discovery stage has odds of about one in 250 of making it to market
2 The commercial strategy of the biotech corporations is to increase the kinds of Bt and HT crops (GM wheat is next on the horizon) and to extend cultivation of these crops and traits to developing countries. Quite simply, GM crops that would ‘benefit’ the poor are not a commercial priority.
Crop trait Proportion of approved crops (%)
Pest resistance 21.4
Herbicide resistance 48.2
Bacteria-virus resistance 8.9
Fat content/type 3.6
Starch content 0
Fungus resistance 0
Plant growth 0
Environmental stress 0
Antibiotic resistance 0
Source: Harhoff D, Regibeau P & Rockett K, 2001
This article first appeared in the Ecologist July 2003
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