GENET archive


AGRICULTURE & DEVELOPMENT: South Africa: Genetically Modified Foods

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SOURCE:  Science in Africa

AUTHOR:  Jennifer Thomson


DATE:    12.11.2013

SUMMARY: "Humans have been meddling with nature since time immemorial. A chihuahua would hardly compete with the wolves from which dogs were bred. Maize would not be recognized by the ancient middle Americans who began breeding from its progenitor, teosinte, some 7,500 years ago. And wheat would probably not be passed by food regulatory authorities if it were introduced today because of the numbers of people who are allergic to it.  "

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Breeding programmes that have given us nearly all the food we eat today are inherently hit or miss affairs. It takes two different varieties of a plant which have individual characteristics that make each attractive. One might have a high yield and the other might be resistant to an insect pest. 

Breeders will cross-pollinate these two varieties, obtain seeds and plant these. The plants that grow will be a complete and random mix of the genes from the parental plants. The breeders will then select those plants that have high yields and insect resistance. Unfortunately, due to the randomness of the process, those plants might be sensitive to a virus that was not a problem in either parental strain but, when their genes were mixed, it became a problem. 

Therefore those plants will have to be discarded and others selected. This is an extremely inexact process and very time consuming. However, it works in time - witness the abundance of crops that have been developed in the past thousands of years. 

Genetic engineering can be used to speed up this process. It will certainly never displace breeding - indeed genetic engineers are heavily dependent on plant breeders to ensure any introduced gene exists and operates in concert with the other genes of the plant. What genetic engineering of plants enables scientists to do is to take any gene from any living being and introduce it into a plant. 

The resulting transformed, or transgenic, plant is referred to as a genetically modified (GM) plant. The genes that are introduced are very carefully characterised - their entire DNA sequences will have been determined. 

Therefore this part of the process is, unlike breeding, extremely precise. What is not precise is where the gene is introduced into the plant. Although scientists are working on improving this aspect, at present genes are largely inserted into plant DNA in a random fashion. 

Therefore, once the genes have been introduced a great deal of work is required to ensure that the inserted genes and the plant's own genes work harmoniously together. 

Critics of GM plants often cite this randomness of insertion as being totally unacceptable. However, they omit to explain that in nature genes jump all over the place within living organisms. Indeed some of the plants in your garden, especially those with variegated leaves, may well be the result of jumping genes. 

Potatoes genetically modified to be resistant to the Colorado Potato Beetle Most traits that have been introduced into plants to date involve herbicide tolerance and resistance to insects. These are the so-called "input traits" of the 1st generation of GM crops. 

They are traits that improve the productivity of a crop and decrease dependency on chemical pesticides and herbicides. They are mainly of benefit to seed companies and farmers, and this has led to much of the antagonism against GM crops - people see the big corporations making fat profits and they see no gain for themselves, the consumers. 

A potato field decimated by the Colorado Potato Beetle However,  let us not lose sight of the fact that in Africa farmers are often also the consumers. 

But the 2nd generation of GM crops are in the pipeline. These contain the so-called "ouput traits" which will have more obvious advantages to consumers. These include "golden rice" which contains a compound that is converted by the body into vitamin A and hence prevents millions of poor Asian children from going blind. 

They include potatoes with a higher starch content that absorb less oil during the frying process; tomatoes that taste better and rot less, and oils with more healthy unsaturated fats. 

So why do newspaper headlines scream "Are you eating Frankenstein foods?', "Beware of genetic pollution!" and "Genetically modified foods reap a harvest of fears". Why don't we read headlines such as "Genetically modified rice saves millions of Asian children from blindness?' or "Genetically modified sweet potatoes save East African crops from virus plague"? Certainly bad news sells better than good news. 

Let us look at safety of foods derived from GM crops for human and animal consumption. First of all it is important to realize that there is no such thing as safe food - there is only the safe use of food. 

You or I could probably die, or at least become very ill, if we ate nothing but eggs. However, GM plants are treated as if they were toxins - the only plants (or foods derived from them) to be treated in this way. 

They are subjected to a battery of toxicological tests, including ones that can detect potential long-term effects on humans or animals. Only then are they declared safe. By comparison, when a new food is introduced into the market, not derived by genetic modification, no such tests are required. 

Take for example one of my very favourite foods, the peppadew. How long has that been on the market and who has checked that it might not have any long-term adverse effects on humans? Please don't misunderstand me - I am quite sure peppadews are perfectly safe for human consumption - but the fact is they haven't been tested in the way GM plants are. 

Let us now look at how safe GM crops are for the environment. As most GM crops are either resistant or tolerant to insects and herbicides, I will concentrate on these. Can animals die from eating an insect resistant plant? No, the toxic protein produced by the plant is specific to certain groups of insects and not to animals. Can non-targeted insects be killed by insect resistant crops? 

Insect resistant crops produce one extra protein that causes the death of insects that feed on that plant. However, insects that eat the pollen produced by the insect resistant crops could be killed. There was an outcry in the media when a study showed that pollen from insect resistant maize could kill Monarch butterfly larvae. "GM pollen that can mean a cloud of death for butterflies" was one such headline. What wasn't disclosed was that this was a laboratory study in which Monarch butterfly larvae were force fed leaves covered with the pollen. 

The press omitted to comment on the fact that subsequently 20 or so field trials had shown that not only was there no effect on Monarch butterfly larvae but that the larvae preferentially choose not to eat leaves that contain pollen - whether genetically modified or not. In fact, since the widespread acceptance of insect resistant crops in the USA, populations of Monarch butterflies have increased, possibly due to the decrease in the use of insecticides. 

What about herbicide resistance? Cynics say that this is a ploy by chemical companies to force farmers to buy their herbicide. Certainly chemical companies wish to make profits - that's what their shareholders require - but in the case of the herbicide Roundup it is less harmful than many other weed killers as it is readily biodegradable. 

Certainly the introduction of herbicide resistant crops has caused a decrease in the number of times crops are sprayed, and as many sprayings are from airplanes which spread the chemicals far and wide, that is clearly beneficial to the environment, and to the health of people on neighbouring lands. 

However, I am not saying that all GM crops are safe in all environments. Each must be looked at carefully on a case by case basis. For instance, it would be foolhardy to allow the release of a herbicide resistant plant if it could cross-pollinate a potential weed. Although such herbicide resistant weeds could potentially be eliminated by other weed killers, it is still not a good idea. 

In South Africa we have a Genetically Modified Organisms Act which is administered by the Department of Agriculture. They have the responsibility of considering each application for a field trial or commercial release on a case-by-case basis. 

I am also not saying the GM crops are the only answer to food shortages in, amongst other places, sub-Saharan Africa. It has been calculated that if we continue with current agricultural practices Africa south of the Sahara will have a grain shortage of 88.7 million tons by the year 2025. 

Clearly something has to be done. Certainly there is enough food produced in the world to feed everyone - but the problem is how to get it to the people in need? Certainly we should stop wars, eliminate corruption so that food gets to the right people, build roads and rails to transport the food, but how long will that take? 

In the meantime, GM crops, that give increased yields, are just one of the ways in which we can tackle the problem. Because Europe has enough food and don't want GM foods should we allow them to dictate to us as to what is best for Africa?