Dispelling 'Frankenfear'
The case for genetically modified food
Email
us
Back to Pro Global
Established 7 July 2000.
Last modified 17 July 2000.
http://www.oocities.org/socialism_2000/pages/genetic.html
Genetic engineering involves the modification of genes in plants and animals in order to give them new attributes. This can involve the introduction of a gene from either the same or another specie or the modification of the expression of one or more of a given plant's own genes. It is also called recombinant DNA technology.
Genetic engineering is part of biotechnology which in the case of plants also includes the application of plant tissue culture and molecular marker technologies.
The application of recombinant DNA technology to facilitate genetic exchange in crops has several advantages over traditional breeding methods. The exchange is far more precise because only a single (or at most, a few), specific gene that has been identified as providing a useful trait is being transferred to the recipient plant. As a result, there is no inclusion of ancillary, unwanted traits that need to be eliminated in subsequent generations, as often happens with traditional plant breeding. Application of recombinant DNA technology to plant breeding also allows more rapid development of varieties containing new and desirable traits. Further, the specific gene being transferred is known so the genetic change taking place to bring about the desired trait also is known, which often is not the case with traditional breeding methods where the fundamental basis of the trait being introduced may not be known at all. Finally, the ability to transfer genes from any other plant or other organism into a chosen recipient means that the entire span of genetic capabilities available among all biological organisms has the potential to be genetically transferred or used in any other organism. This markedly expands the range of useful traits that ultimately can be applied to the development of new crop varieties. As a hypothetical example, if the genes that allow certain bacteria to tolerate high external levels of salt can serve the same purpose when transferred into crops such as potatoes, wheat, or rice, then the production of such improved food crops on marginally saline lands may be possible. REF
In the next few decades there needs to be enough food to feed a couple of billion more people and in the majority of cases they need to to be fed a lot better than they are at the moment. Furthermore, this needs to be achieved with natural resources that have been diminished both in quantity and quality. In other words we need to be producing more with less. Essentially this means vastly improving the way we produce food.
GE can play an important role in this. It is not the total solution but it is a necessary and major part of it. It’s importance will, however, increase with time. GE is only in its infancy and in developing countries there is still considerable room for simply catching up with the better farming methods of developed countries.
Pressing food needs
There is wide agreement that the population will increase by 2 billion over the next 20 to 25 years. With population now at around 6 billion that would represent a one third increase in the number of mouths to feed. If the population increases to around 10 billion before reaching an expected plateau in the middle of the century, there will eventually be a two third increase over current levels.
Even production for existing needs is inadequate. At the moment about 2 billion people are undernourished. This is a third of the world’s population. About half of these suffer serious malnutrition while the other half have various micro-nutritional deficiencies in their diet.
As well as eliminating malnutrition, there is also a need to bring everybody up to the level of an affluent but sensible eater. This means a diversity of diet that allows food to meet all nutritional needs and also be pleasant to eat. With existing technologies this would place far more demand on natural resources than a staple grain crop and a small selection of vegetables.
Resource problems
Not only do we need to produce more. We need to do it with less. Resources at their limit or being degraded or reduced.
At the same time the ability of conventional breeding methods to produce higher yielding and more robust plant varieties has fallen off significantly in the last decade or so as the potential of these methods is exhausted.
The situation may be further aggravated by changing weather patterns that will affect growing conditions and require the development of new methods and new plant varieties.
GE solutions
There are numerous ways in which GE can help to increase food supply with the same or less resources. Here is a far from exhaustive list:
Better yield:
More robust plants:
Saving on resources
Post farm improvements
Improvement in food quality
Opponents of genetic engineering often claim that food security is a distribution problem rather than a production problem. If the world’s food supply were equally distributed everyone could have an adequate diet. As it is, average calorie intake varies from under 2000 in some really poor countries to around 3500 in developed countries. In the developed world many people eat to excess and prefer types of food that use lots of agricultural resources for a given level of nourishment. For example, the grain that goes into producing meat, would have fed more people if consumed directly. In developing countries, the poor are hungry because they have small and infertile land holdings or because they are unemployed and don’t have the income to buy food. And part of the reason for the lack of good land for the poor to produce food on is the fact that a significant proportion of the land is devoted to producing cash crops for export to developed countries.
The first point to make is that even if mere redistribution were a feasible solution at present, it certainly won’t be in the future. Firstly, over the next 20-25 years there will be another 2 billion mouths to feed. Secondly, given the depletion of agricultural resources such as land and aquifers, even maintaining current output will require major improvements in agricultural methods. In other words we will have to produce more with less.
The second point to make is that a serious redistribution simply is not going to happen. This is plain to see in the case of a major part of such a redistribution, namely that from the richest to the poorest countries.
This would require convincing about a billion people to change their eating habits. Then you would have to ensure that the food they are no longer consuming continues to be produced and is distributed to its new consumers. This would require the government paying farmers from increased taxes equivalent to the amount that people are no longer spending on food. The food would then be shipped to where it is needed and distributed freely or at below cost prices. In some cases this would require building distribution infrastructure such as roads, rail, port facilities and airports. In other words, you would not only have to get people to spend less on food but also convince them to hand over the money saved to the government. Simply describing what would be involved, is enough to show how unrealistic the notion is!
Besides, the ‘problem’ of increased food consumption by the better off is expected to grow as people in middle income countries continue to demand increasingly varied diets including ever greater amounts of meat. For example, meat consumption in Latin America, the Middle East and China is far higher than in Africa and India and still rising.
This distribution view of the food problem is part of a cargo cult explanation of poverty generally. Developing countries are not poor because of a limited ability to produce things, due to a lack of capital accumulation, but rather because they have less than their ‘share’ of a given quantity of goodies. It is a bit like saying that poor countries have poor sewerage systems because they have less than their share of the stock of sewerage pipes - or to be only slightly less ridiculous, because they have less than their share of the stock of sewerage pipe factories.
What about distribution within developing countries? In some places the small farmers may be politically strong enough to force a distribution that improves their food security. However, there is no sign of a general move in that direction. Furthermore, small scale agriculture is not the road to take if these countries are to develop economically and socially.
Of course, the last thing that anti-biotech greenies want is economic development in Third World countries. They want us all to return to some agrarian golden age and for subsistence farmers to remain that way and for their relatives in the cities to return home.
Around half the world's population live in rural areas in developing countries, and poor farming families from these regions make up a majority of those currently suffering from malnutrition. Genetic engineering could significantly assist these people. Whether it will or not will depend mainly on sufficient increases in government funding for the kind of research and development that would meet their needs.
Also important will be the establishment of property right regimes that ensure that the results achieved by life science companies are not kept from the poor. The active good will of these companies will also be important and would depend mainly on heavy social and political pressure.
Extension services would also have to be vastly improved to ensure that farmers are able to make effective use of the new plant varieties.
In some cases GE is the only solution to a particular problem. In other cases it is just one of a number, with GE being the most appropriate solution in some cases but not others. Opponents of GMOs, however, argue that it is never the appropriate option.
Information provided here is not comprehensive, but is simply suggestive of what is possible.
To serve poor farmers, genetic engineering research has to be directed at the staple crops they grow and which are their main source of nutrients. These include white maize, cassava, sorghum, millet, sweat potato and plantains. And the plants improvements would need to better adapt them to the adverse environments the farmers face, be suitable for small farms and not require expensive inputs they cannot afford.
There are a number of ways in which genetic engineering could help poor farmers and we discuss them in turn:
Increase effective yield
Effective yield can be increased by increasing biological yield, improving the ability of crops to deal with difficult conditions, extending post-harvest life and by developing asexual reproduction.
Biological yield Scientists have had some preliminary success in transferring the greater photosynthesis efficiency of maize to rice. REF It needs to be adapted to the major varieties and is expected to be readily available in five years. The new rice is expected to increase yields by over 20 per cent. Similar improvements could also be made to barley and wheat which share rice’s lower photosynthesis efficiency.
Another promising development is the identification and isolation of a dwarfing gene that could bring yield improvements in a number of crops comparable to those in wheat and rice in the Green Revolution. REF Poor farmers could also benefit from improvements in aquaculture yields.
Ability to deal with difficult conditions Poor farmers often farm under the worst conditions. These include infertile soil, inadequate water, flooding, excessive heat and extreme and variable weather. Genetic engineering could help in all of these areas.
In India, scientists are developing a transgenic rice to help plants survive when submerged for long periods, a problem common in Asia. REF
Research on ocean algae could lead to drought, freeze and salt tolerant crops.REF And the transfer of genes from mangrove tree species also promises greater salt tolerance. REF
Genetic engineering should also be able to deal with the problems of sub-tropical and tropical soils. These tend to be acidic and have high levels of aluminum and manganese. Work is presently being done on sugar beet plants with an elevated expression of a gene that enhances tolerance to aluminum, and also increased up-take of phosphate in the acidic soil.REF And researchers in Mexico have added two genes to rice and maize that appear to increase tolerance to aluminum. REF
Other promising areas for transgenics include improving the nitrogen-fixing capacity of crops and controlling water loss from leaves.
Eliminating disease Agriculture in developing countries is wracked by disease. Researchers are currently working on a genetically modified rice plant that is resistant to the yellow mottle virus (RYMV), which is endemic to Africa. It can devastate rice harvests and contribute to famine in areas where the cereal is an important food staple.REF Other work in progress includes pearl millet resistant to downy mildew REF, disease-resistant bananas and virus resistant sweat potato REF
"Africa's crop production per unit area of land is the lowest in the world. For example the production of sweet potato, a staple crop, is 6 tonnes per hectare compared to the global average of 14 tonnes per hectare. China produces on average 18 tonnes per hectare, three times the African average. There is the potential to double African production if viral diseases are controlled using transgenic technology.
"The average maize yield in Africa is about 1.7 tonnes per hectare compared to a global average of 4 tonnes per hectare. Some bio-technology applications can be used to reduce this gap, for example in the case of the maize streak virus (MSV), which causes losses of 100 per cent of the crop in many parts of the continent. A biotechnology-transfer project is under way to develop MSV-resistant varieties. …
"An opportunity to work in the private biotechnology sector abroad resulted in the development of a transgenic variety that is resistant to sweet-potato feathery mottle virus, which can reduce yields by 20-80 per cent. Control of this disease will improve household food security for millions. … Similar projects are under way for bananas, sugar cane and tropical fruits." REF
According to Norman Borlaug, the father of the ‘Green Revolution’:
If we could get a gene from rice - because rice does not suffer from rust - and then use it to protect other crops that suffer from rust like wheat, that would be a big revolution, and that will not be dangerous to human health in any way.REF
Combinations of traits and crops presently being field-tested in developing countries include virus- resistant melon, papaya, potato, squash, tomato, and sweet pepper; disease-resistant potato; and delayed-ripening chili pepper. REF
Desease is one of the main reasons for poor livestock productivity in developing countries. This is particularly true for Sub-Saharan Africa, where animal losses due to disease are estimated to be $4 billion annually, approximately a quarter of the value of live stock production. Tse tse fly - transmitted trypanosomosi sandtick-born diseases are the most important livestock disease problems in this region. REF For some illnesses existing counter-measures have proven unsatisfactory, with vaccines created by genetic engineering seeming to be the only answer. The Livestock Research Institute ( ILRI) is currently developing a vaccine against Theileria parva the parasite that causes East Coast Fever in cattle.
There is good reason to believe that vaccines will be produced against some or all of the major animal diseases, given the necessary scientific and financial resources. However, the complexity of the problems that are being addressed should not be underestimated. The opportunities presented by advances in biotechnology can only be exploited effectively if there is a thorough understanding of the biology of the target pathogens and the diseases they produce. Such an approach requires substantial investment in strategic research. REF
Scientists have also developed an experimental potato hybrid that contains genes to resist a new, more virulent strain of the so-called "late blight," the disease that caused the Irish potato famine in the 1840s. REF
Insects Insects can do damage either in their own right or as vectors (carriers) for diseases. Current work in progress in developing countries includes insect resistant cowpeas REF, rice, soybean and tomato REF
Weeds Weeds in developing countries cause serious output losses and weeding consumes an appalling amount of human labor.
While dangerous pesticides have been over-used in many developing countries, herbicide use has been very low even thought most herbicides are far less toxic than pesticides. Yet weed control is a major time, labour and resource consuming task for most farmers, and in particular for resource poor farmers with limited access to inputs such as affordable herbicides etc. It is estimated that more than 60% of developing country farmers time is spent in weeding. Much of this weeding is often done by women and children and is often unpaid work. There is a very convincing case to be made that herbicide resistant crops could in the near term offer significant, economically accessible, advantages to many farmers in developing countries, in particular poorer farmers with limited labour availability.
In particular, there are many weed problems faced by farmers in developing countries for which no effective control measures have been developed, with or without herbicides. These include the parasitic broomrapes and witchweeds (Striga spp). The areas infested with such weeds are vast and expanding. For example, a survey of 180,00 square kilometres in Nigeria found that 70% of fields were infested with witchweed seeds. In the seven agro-ecological zones of sub-Saharan Africa witchweeds are generally listed as the worst pests affecting agriculture. Witchweeds infest the grain crops of more than 100 million people in sub-Saharan Africa and Asia, reducing yields by 50%, and by more in drought years. Labour intensive weeding is largely ineffective against such weeds. Crop yields could potentially be doubled if such weeds could be controlled. In addition labour spent in weeding could be released for other more productive activities, such as increasing literacy and schooling for children.
It was recently found that it is possible to control Striga spp using imadizoline resistant maize. One such strategy of potential utility to developing country farmers is being developed whereby only the transgenic seed is treated with high levels of a systemic imadizoline with a resultant excellent control of Striga.. Using $5 of herbicide gave $100 of increased maize yield per hectare in Striga - infested areas in Kenya. Such strategies would require resistance management measures to ensure that Striga resistance to the herbicide would not evolve. Herbicide resistant crops could form part of integrated weed management systems, where resistance management strategies are used to ensure that herbicide tolerance does not develop in the weed flora. However it would seem that current biosafety regulations will limit African farmers access to herbicide tolerant crops in the near term, even for crops such as maize which have no weedy wild relatives in Africa. The FAO held a workshop on regulating herbicide tolerant crops in 1998 and is reported to be in the process of publishing Guidelines for the Regulation of Herbicide Tolerant Crops. REF
As well as developing herbicide resistant crops, genetically modified plants have also been trialled with lower leaves that create a shade which is unwelcoming to weeds.
Post harvest Increased shelf life through delayed ripening can be very important where refrigerated storage and transport facilities are limited. Work is currently being done on a delayed-ripening chili pepper. REF
Apomixis Gene Apomixis gives plants the ability to reproduce asexually. If farmers had apomictic versions of maize and other hybrids, they could then replant seeds from their own harvests instead of purchasing fresh seed each year. The need to purchase fresh seed has prevented many small farmers from using improved hybrid varieties. They could save seed of their best plants for use the following cycle. Selection of superior, locally-adapted varieties would be enhanced. Apomixis would also allow propagation through seed of crops that are currently vegetatively propagated such as cassava, potato, sweet potato and yams. REF
Improve nutritional value of staples crops
The diet of poor farmers often consist primarily of a few staples such as cassava, wheat, rice and corn (maize) that are poor sources of some macronutrients and many essential micronutrients. Genetic modification offers the possibility of enhancing the nutrient value of these crops.
Hidden hunger, such as protein and micronutrient deficiencies, is a widespread and endemic problem for the worlds poorest people, especially women and children. A range of transgenic approaches have now been developed to nutritionally improve the amino acid profile of crop protein, either by transferring genes encoding more nutritious proteins from other species, or by manipulation of crop biosynthetic pathways to increase the nutritional profile of endogenous proteins. Where transformation protocols have been developed, many important legumes (whether landraces or modern varieties) such as peanut, beans, clover etc could feasibly be nutritionally improved through the transfer of methionine-rich protein genes from species such as sunflower. Sunflower was chosen as the gene source because, unlike Brazil nut, the seed is not known to cause any allergic reactions.
Insufficient intake of dietary vitamin A is implicated in the death of approximately 1-2 million children annually. In South-East Asia, every year an estimated 5 million children develop the eye disease xerothalmia. Unfortunately, many staple crops such as rice are deficient in dietary vitamin A. In addition, the vitamin A containing tissues of rice (embryo, aleurone layer) are removed during milling of rice. Genetic engineering have now developed milled rice which accumulates vitamin A to provide one means of facilitating increased dietary intake of vitamin A from staple foods. If technology transfer of such vitamin A rich crops can reach its intended clients, it is likely that the transgenes used to increase vitamin A production could be applied to other crop species or varieties in locations where vitamin A deficiency is a medical problem. Similar approaches to combating micronutrient deficiencies by increasing both the content and availability of iron in transgenic rice are showing much promise. REF
Diggle, a mutant pea plant with a suicidal love for iron, may someday offer scientists a biotechnology approach for reducing anaemia. Anaemia, or iron-poor blood, affects 2 billion people: about one-third of the world’s population, according to World Health Organization statistics. Inadequate iron in the diet is the leading cause.
Plant physiologist Michael Grusak at the Agricultural Research Service would like to understand and modify Diggle’s "stupid plant trick." ARS is the USDA's chief scientific agency. Grusak's major aim: improve the iron content of staple crops such as rice. This would especially benefit people in developing countries, who mostly eat vegetarian diets. Only 5% of the iron in plants is bioavailable: usable by the body as a nutrient. By contrast, 30 to 50% of iron in meat is usable. REF
Of course in the long term most nutrient deficiencies should be corrected by a more varied diet. Even in the short term, there may be many cases where efforts at diversifying food production would be a more efficient use of limited resources than genetically modifying some local staple crop. A report released by Christian Aid expresses a blanket opposition to the Vitamin-A enabling gene on the basis that there are always better alternatives. REF Unfortunately, it does not provide readers with the empirical evidence they would need to reach such a conclusion.
Medical benefits
Vaccines in food These would be easy to preserve, store and dispense.
Human disease is a major constraining factor to labour availability in many agricultural projects and to socio-economic development in general in developing countries. Lack of effective cold storage facilities limits the efficacy of linear supply chains for many vaccines. Production of effective oral vaccines against major tropical diseases in transgenic plants may be an extremely appropriate and low technology means of decentralizing both vaccine production and distribution in developing countries. The potential feasibility of producing oral vaccines in transgenic plants has now been demonstrated for diseases such as cholera - toxin B 113 and hepatitis B 114 . If they are made widely accessible, such transgenic plants may be of major utility to hospitals and medical centres in providing a reliable and cost effective supply of heat-stable vaccines and other protein based pharmaceuticals. REF
The National Health and Medical Research Council (NH&MRC) has granted $180,000 to researchers in Adelaide and Melbourne to use biotechnology with traditional plants to develop a vaccine against lethal diseases such as measles and cholera. The project will use bananas, potatoes, peas and other common fruits or vegetables as vaccine agents. ….
"Existing vaccines are expensive and there are also significant problems with the delivery strategies for vaccines in developing countries," says Dr Dry. "Vaccines are living organisms, which must be correctly stored and transported at the right temperature - and that’s often difficult in the Third World. As well, you need a semi-skilled person to give the injection."
Dry, Wesselingh and Strugnell, like fellow researchers in other parts of the world, believe that development of oral vaccines derived from crops easily grown in local regions may improve vaccine delivery and, in the case of diseases which attack the gut, may prove superior to injectible vaccines. …
The researchers anticipate that the next stage could yield a safe, effective measles vaccine for babies within five years. REF
There are no known hazards from the simple act of transferring genes from one organism to another. Hazards that we are aware of are in the specific application – the particular plant and the environment in which it is grown. In this way it is very much like any other knowledge or technology.
Safe use basically comes down to a regulatory regime that specifies how new GMOs are to be tested for hazards and the conditions of use.
Whether a particular risk is considered acceptable will depend in part on the perceived benefits - in other words what you give up by not taking the risk.
There can also be risks in not developing particular GMOs. Elsewhere, we discuss genetic engineering’s potential contribution to food security and assisting poor farmers. Failure to use it in these areas could increase the possibility of very undesirable outcomes.
Most of the risks from specific genetic engineering applications about which opponents have raised alarmist concerns are proving to be minimal risks and/or easily eliminated. The more renowned cases are discussed below.
Monarch butterfly caterpillars
A study performed at Cornell University examined what happened when Monarch butterfly larvae were fed milkweed with large amounts of pollen from Bt corn. As stated by Dr. John Losey, the lead researcher of the study, "…our study was conducted in the laboratory…it would be inappropriate to draw any conclusions about the risk to monarch populations in the field based solely on these initial results." REF
Toxicity
From a toxicity standpoint, a Cornell University study showed that if monarch caterpillars were fed Bt corn pollen, about half would die. That particular study made a lot of headlines. However, only one type of Bt corn pollen was tested. Not all Bt pollen are alike and there are many types of commercially available Bt corn. Recent studies indicate that a few types of Bt corn pollen may kill or slow the growth of monarch caterpillars, while other types of Bt pollen have no impact. In fact, monarch larvae that fed on one type of Bt corn pollen actually weighed more than those fed conventional corn pollen. REF
Different from wild conditions
In response to [the Cornell] study, leading researchers, entomologists and weed scientists headed to cornfields in the summer of 1999 to assess the risk of Monarch butterfly exposure to Bt corn pollen under natural conditions. The studies show that the concentration of Bt pollen adhering to milkweeds within just a few meters of cornfields is typically too low to cause mortality of even small Monarch caterpillars that might be present during pollen shed. These latest findings provide reassurance for the safety of the Monarch butterfly in a real world situation. REF
... [T]he Cornell laboratory study was a "no-choice" study, meaning that the caterpillars had no choice but to eat only the pollen-dusted milkweed leaves. Other studies have shown that monarch caterpillars may avoid leaves covered with pollen either by feeding on other leaves with little or no pollen or feeding on the bottom of leaves, which reduces their chance of exposure to the pollen.
Because monarch caterpillars feed only on milkweed plants and most farmers try and keep their corn fields free of weeds, there is little chance that milkweeds or monarch larvae are present in a corn field. In addition, corn pollen is relatively heavy and does not drift more than 30 feet from the edge of a corn field, so any milkweed plants outside of 30 feet of the field will essentially have no corn pollen on their leaves.
Given all of this evidence, the risk of Bt corn to monarch populations is probably low. Reducing the frequency of mowing right of ways and protecting the monarch butterfly over-wintering sites in California and Mexico will have a more impact on monarch population density than the planting of Bt corn. REF
There are a number of reasons that the effect of Bt corn pollen on monarchs is likely small. Corn pollen is produced for only a short time during the growing season. Corn pollen is heavy and is not blown far from corn fields by the wind. Farmers control the monarch's primary host plant, milkweed, in and around their fields, just as they control other weeds. Finally, it is not known whether monarch butterflies will choose to feed on milkweed plants with Bt pollen when given the opportunity to choose other plants in the field. REF
Existing practices are more hazardous
Indeed, the Bt in those corn plants was chosen in order to protect against damage from insects closely related to the monarch butterfly. And, the pesticides used on traditional crops to kill insects are known to harm butterflies, as well. REF
Despite popular belief, Losey, et al. (1999) demonstrated nothing new other than that force feeding monarch caterpillars is still not as hazardous as using chemical insecticides. REF
Further research
However, USDA and EPA scientists have had discussions with the study's researchers to learn more about ongoing experiments. And USDA scientists in Iowa are currently conducting follow-up studies. We are also working to identify follow-up information and research that would be useful to refine our understanding of how monarchs and corn pollen interact in the field. USDA is committed to further research on the potential impacts of new technologies in agriculture. REF
Countermeasures
Strategies to minimize impact on non-target insects are also being developed. For example, the current generation of Bt corn is aimed at reducing crop losses to an imported pest from Europe, the European corn borer. This pest eats corn stalks. Varieties of corn are already under development that could express Bt or other genes of similar effect only in corn stalks, and not in other parts of the crop (e.g., leafs, pollen). Likewise chloroplast transformation described above will eliminate expression in pollen. Such corn varieties would also eliminate entirely any risks to non-target organisms that might come from Bt containing pollen. REF
There is a concern that pesticide or pest resistant genetically modified crops may out-cross with weedy relatives to create super weeds.
Assertions that cultivation of herbicide resistant plants will result in "superweeds" through gene flow are misleading and alarmist. Gene flow is the exchange of genetic information between crops and wild relatives. The movement of genes via pollen dispersal provides, in principle, a mechanism for foreign genes to "escape" from a genetically engineered crop and spread to weedy relatives growing nearby. Gene flow becomes an environmental issue when the associated trait confers some kind of ecological advantage. This is a particular concern in the case of herbicide resistance genes, for example, where transfer of the resistance trait to weedy relatives that are more difficult to control. REF
Out-crossing unlikely
It is important to remember that for any transgene to spread (nuclear or plastomic), there must be successful hybrid formation between a sexually compatible crop plant and recipient species. The two species must flower at the same time, share the same insect pollinator (if insect-pollinated), and be close enough in space to allow for the transfer of viable pollen. Thus, the transfer of transgenes will depend on the sexual fertility of the hybrid progeny, their vigor and sexual fertility in subsequent generations, and the selection pressure on the host of the resident transgene. REF
Outcrossing from domesticated crops to weedy and indigenous wild relatives is possible, but the frequency of such events is extremely low. These issues are considered by regulatory authorities in assessing the risks that might flow from the general release of genetically modified organisms. REF
Are there weedy relatives in the region?
The presence of weedy relatives will depend on where the crop is planted. For example, crops like corn, soybean, cotton, or potato have no weedy relatives in the United States.
In Africa or Asia, there would be little likelihood of herbicide resistance jumping from corn to a wild relative; corn is not native to these regions, so there are no wild relatives. In Mexico and Central America, however, the threat would be much greater, since the wild relatives from which corn was originally domesticated are still present. REF
Resistance would be to a very specific control measure, for example Round Up herbicide. Could use other measures. Although may have to adopt alternative control measures that are desirable for other reasons including environmental impact. For example, more powerful herbicides.
Would it be more weedy?
Any long term effects will be contingent on whether the transgene can confer a selective advantage and on the likelihood of persistence and spread of the transgene in weedy of natural populations. REF
What about a domesticated plant itself becoming a weed?
..., very few domesticated plants naturalise, and almost none are weeds in natural ecosystems. It is difficult to see how the traits that are currently being introduced into genetically modified organisms will improve their fitness in ways that allow these plants to pose a threat to the environment. REF
Risk reduction/elimination measures
There are also strategies to reduce the, however small, risk of gene flow from transgenic crops. One possibility is the use of male sterile plants, which works well but is limited to a few species. For the many crops in which chloroplasts are strictly maternally inherited, which is to say not transmitted through pollen, transformation of the chloroplast genome should provide an effective way to contain foreign genes. Henry Daniell and colleagues at Auburn University introduced a gene for herbicide resistance into tobacco, showed that it was stably integrated into the chloroplast genome, and demonstrated that transgenic plants contained only transformed chloroplasts. This result advances the potential for chloroplast transformation to be an effective strategy to manage the risk of gene flow (Daniel et al., 1998).
To test the theory of gene flow for herbicide tolerant genes introduced through chloroplast transformation, Scott and Wilkinson (1999) studied a 34-km region near the Thames River, United Kingdom where oilseed rape is cultivated in the vicinity of a native weed, wild rapeseed. Oilseed rape, the cultivated form of Brassica napus, and the wild rapeseed (B. rapa) are capable of exchanging pollen to produce viable hybrids. The study was designed to determine whether oilseed chloroplasts could be transferred to wild rapeseed, and how long the hybrids and maternal oilseed plants would survive in the wild. To identify chloroplasts, the authors created primers specific to chloroplast DNA non-coding regions. In PCR experiments, oilseed chloroplasts produced a single amplification product of 600 bp, whereas wild rapeseed produced a 650 bp product. In all cases, the chloroplasts from hybrid plants contained the PCR product of the maternal line demonstrating that they are not transferred in pollen.
The authors studied the frequency of hybrid formation and viability of oilseed and hybrids in non-cultivated areas over a three-year period. Their studies show that oilseed has a very low survival rate outside cultivated fields. On average, only 12-19% of oilseed survived each growing season. At the same time, a very low level of natural hybridization was observed (0.4-1.5%). Taken together, the results indicate that there is a very low possibility of transgene movement into feral populations of maternal lineage. However, the persistence of the maternal line in the wild will be of limited duration. REF
The infamous potato study
A study performed by Arpad Pusztai, formerly of the Rowett Research Institute in Scotland, reported that rats developed intestinal problems after being fed raw genetically modified potatoes. This study was highly criticized by independent experts including the Rowett Institute itself, which discredited the study entirely after performing an audit of the research.
Pusztai had to retract most of his original claims. The study was however later accepted and published in The Lancet, one of Britain's leading medical journals, although the same journal commented that the study proved no link between biotech potatoes and intestinal problems in the rats. The Lancet seems to have published the paper for fear of being accused of suppression rather than on its merits. Normally papers on laboratory research are not published in academic journals if referees detect major flaws in the testing methodology. One of the independent referees said that all the study proved was that "raw potatoes are not very nutritious."
Allergic reactions
Another potential risk posed by GMOs is the introduction of genes from organisms that cause allergic reactions in some people. This would pose a problem for people with allergies if they are unaware of the allergy danger or if the GMO is a widely used ingredient.
The actual risk is quite low and there is no evidence of anyone suffering an allergic reaction to GM food.REF Very few genes have the ability to cause allergic reactions and would be easily identified well before the possibility of release.
Actually, the fact that genetic engineering involves the transfer of a single or only a very few genes makes it even easier to test the allergenicity of the introduced new traits. Each gene encodes a single protein product, which can be readily tested for its allergenic effects.REF
Internationally, the evaluation of allergenic potential is an integral part of a regulatory approval process. Labelling is mandatory if a known allergen is transferred to a food source not normally associated with that allergen. Again, no products developed using biotechnology that are currently on the market fall into this category.REF
Using genetic engineering to remove allergens from existing food.
Instead of GMOs posing an allergy danger, the exact opposite may prove to be the case. Genetic research is underway that could lead to the removal of allergens and toxins from existing food.
Antibiotic resistance
A frequently mentioned concern is that widespread human consumption of genetically modified foods might lead to an increase in diseases resistant to several types of broad-spectrum antibiotics. This concern arose because the plasmid vectors on which foreign genes are inserted frequently also contain antibiotic resistance genes (although these genes were not expressed). Some health specialists worried that if these genes were present in transgenic foods in excessively high levels, they would build up in the bodies of consumers and lead to an increase in diseases resistant to antibiotics. More recently these concerns have been allayed in that researchers have devised transformation techniques which avoid the use of plasmid vectors containing antibiotic resistance genes. REF
There has been concern that the natural predators of insects targeted by pest resistant Bt crops would also be harmed. Bt crops contain a gene that makes them lethal to certain insect pests.
The following comments are taken from the GMO FAQ page at The College of Food, Agricultural and Environmental Science (Ohio State University).
Q. What about other insects? Some are beneficial—could they be harmed by Bt crops?
A. There is a concern that Bt crops could harm insects that are natural enemies of pests that we want to get rid of. Several side-by-side field studies have been conducted, comparing pests’ natural enemy populations in Bt crops (cotton, potatoes, corn) to their populations in conventional crops. Most of these studies have shown that natural enemy populations are either the same or larger in the transgenic crops than conventional crops.
However, two studies did demonstrate that if the pests (in this case, caterpillars and aphids) were reared on Bt crops and are eaten by their natural enemies—lacewings or ladybird beetles—the natural enemies did not grow as fast or reproduce as well as those that fed on pests who ate conventional crops. However, it’s unclear if this lack of fitness was due to the natural enemies eating sick, weak prey, or if the Bt toxin actually affected the natural enemies. The latter is more of a concern.
Right now, however, it looks like the impact of these transgenic crops on natural enemy populations will be minimal and much less than the spraying of broad-spectrum insecticides, which is currently practiced.
Resistance is always a problem with pesticides.
Insects have almost always become resistant when they are constantly exposed to a given pesticide. This could easily happen with Bt crops, especially since most Bt crops produce the pesticide all of the time in all parts of the plant. REF
Threat to organic farming
Another risk linked to the potential emergence of resistance in insects is that Bt might lose its effectiveness as a topical pesticide. Bt-based pesticides are used to control pests in a number of fruit and vegetable crops. Since Bt is naturally occurring, these pesticides are especially popular among organic farmers. If the widespread planting of transgenic Bt crops were to foster the emergence of Bt-resistant insects, farmers who currently rely on Bt-based topical pesticides could suffer important losses. The emergence of Bt-resistant insects could of course also occur from overuse of Bt sprays, although this possibility is considered less likely, since with Bt sprays the exposure to the toxins is less continuous.REF
Counter measures
To avoid or at least slow down the evolution of resistant insects, growers are required to plant refuges of non-Bt plants within the crop. The non-Bt plants should help sustain populations of insects that remain susceptible to the Bt toxin. REF
Also Bt gene ‘recycling’ strategies are being established whereby a range of transgenic varieties each containing a different type of BT protein are released over time or geography to combat the potential ability of the insect pest to overcome any particular Bt resistance gene, and hence minimize the conventional ‘boom-bust’ cycles in variety-pathogen co-evolution." REF
Whether incorporated directly into transgenic plants or applied as a topical pesticide, in order to maintain its usefulness over the long term Bt will have to be used as part of an integrated pest management (IPM) strategy. One strategy for slowing the emergence of Bt resistance is to increase the toxicity of transgenic plants, either by increasing the dosage of toxin present in the plant or by pyramiding several different types of Bt genes to produce a cocktail of natural toxins. Another strategy involves the use of insect refugia, areas free from transgenic crops in which normal non-resistant insects can continue to live. These non-resistant insects can continue to mate with those exposed to the Bt crops, ensuring that susceptibility is maintained in the overall population. In the US, the companies that sell Bt crops now recommend that farmers maintain 20% of their cropped area as refugia and use conventional insect control in these refugia to ensure the survival of non-resistant insects. As of today, the jury is still out as to whether or not the refugia strategy will work. Farmer compliance could potentially become a problem, because if transgenic crops are significantly more profitable, there will be strong incentives for farmers to cheat by not planting refugia. REF
Once selection pressure is applied on a population, that population is effectively enriched for resistant organisms. That is why it is imperative to develop a multi-pronged approach. Integrating crop rotation and ecology with biotechnology is not only feasible but also the logical way to progress. Indeed biotechnology companies like Ecogen and AgraQuest use biotechnology to identify and enrich natural predators of damaging pests.
However, biotechnology supplies yet one more mode of defense. For instance, many variations and combinations of Bt genes are currently being produced to minimize pest selection pressure. … Biotechnology is striving for a "one pest-many genes" paradigm. Molecular biologists recognize the need to study and apply multiple and diverse mechanisms for controlling pests and pathogens to reduce selection pressure. Simultaneous or sequential deployment of different resistance genes has the same rationale as crop rotation. Pathogen evolution is less able to overcome a changing environment or an environment made inhospitable by an array of resistance genes.
There are many sources of resistance genes in addition to those found in nature. Combinations and re-combinations of genes may be used or completely synthetic genes can be developed. By having a range of gene products with subtle variations produced for example through directed evolution (a technology that mimics the natural process of evolution and brings together advances in molecular biology and classical breeding), or, by creating suites of synthetic genes which the target pest would never encounter in nature, the selection for resistance is greatly reduced. Diverse mechanisms of action of gene products can also be employed to reduce selection pressure through a technique called gene pyramiding whereby genes with very different modes of action such as chitinases, feeding inhibitors, maturation inhibitors, and so on, are used in combination. The probability of any single organism overcoming all of these diverse strategies is vanishingly small. REF
To the extent that genetic engineering is helping to increase effective output on existing farmland it is helping to reduce encroachment on environmentally sensitive areas such as forests and mangrove swamps. Most species of flora and fauna are to be found in these areas. Tropical forests are particularly important.
GM plants with pest resistance mean less use of pesticides that effect a wider range of insects.
Herbicide resistant GM plants. In areas where virtually all land is farmland, the targeted weeds may be an important part of the ecosystem. For example, in Britain, over 70 percent of land is farmed, and much of the natural flora and fauna depends on this farm-land. Herbicide would have to be used wisely in these situations. At the same time the use of herbicide with herbicide resistant crops would allow the use of conservation tillage which assists biodiversity.
Unlike conventional tillage, which controls weed growth by plowing and cultivating, no-till agriculture depends on selective herbicides to kill weeds. The resulting vegetation detritus protects seedlings when they are most vulnerable. Soil erosion is reduced. Beneficial insects in the debris are protected. And the till-less technique reduces equipment, fuel, and fertilizer needs and, significantly, the time required for tending crops. It also improves soil-aggregate formation, microbial activity in the soil, and water infiltration and storage. REF
Is the risk to biodiversity posed by the use of a GM crop more or less than the risk posed by non-transgenic options?
In general, any risks of transgenic crops to biodiversity should ideally be assessed relative to other non-transgenic related factors, such as urbanisation, agriculture and land use changes, exotic plant introductions, conventional weeds etc which are more likely to more drastically reduce the geographic ranges of useful crop wild relatives or biodiversity in general. Many risk assessment studies regarding GMOs fail to do comparative studies to assess each particular risk comparative to the levels of risk from other factors. REF
Pesticide resistance could assist biodiversity
Indeed, the use of Bt-crops may have a positive impact on biodiversity. Ongoing monitoring by companies of Bt-corn fields since their introduction shows that insect biodiversity and population densities in Bt-corn fields is significantly higher than in fields treated with chemical pesticide sprays. Bt-corn may help enhance beneficial insect populations that would otherwise be threatened by the use of pesticidal sprays. This could lead to benefits for, among others, insect eating birds and small mammals. REF
GMO’s do not increase any tendency to monoculture and genetic uniformity
There is also the potential loss of biodiversity, for example, resulting from the displacement of traditional cultivars by a small number of genetically modified cultivars, and the potential for increased crop vulnerability resulting from the possible widespread adoption of varieties with simple, monogeneic, disease resistance mechanisms. However, in principle, these latter effects are no different from those that may result from many conventional approaches to plant breeding.
The recent advances in agricultural genomics, marker assisted breeding and transgenesis suggest that useful genetic diversity is actually becoming more accessible to crop researchers with the potential that aggregate increases in genetic diversity within crop genepools could now practically be achieved through increased use of genes from wild relatives and other species. REF
[The use of genetic engineering] very well could tend to decrease the diversity in crop genetic bases, because breeders and molecular geneticists will be inclined to stick with the germplasm they’re already using (and have already invested a lot in). This is not the only factor operating, however, and one can argue that bringing in genes from other species enhances diversity. REF
It is also worth considering that the wild relatives of crops, although a major genetic resource, are actually rarely used in the breeding of plant varieties, because of practical difficulties in using such exotic germplasm in breeding programmes. With modern biotechnological methods the use of such resources may increase.REF
The argument that adoption of biotechnology crops is "creating genetic uniformity" inducing vulnerability to new matching strains of pathogens is incorrect. Transgenes are added to existing locally adopted germplasm and have no inherent influence on the genetic variation of the varieties planted. For example, there are over one thousand Roundup Ready varieties of soybeans cultivated in the United States alone. Hence, adoption of biotechnology has not increased the vulnerability of germplasm to homogeneous or other strains of pathogens and has not led to genetic erosion. Quite the opposite. Biotechnology tools are allowing traditional varieties to be revived and safeguarded (see for example Woodward et al., in this issue) or develop new genetic variation. REF
Apomixis Gene Apomixis gives plants the ability to reproduce asexually. If farmers had apomictic versions of maize and other hybrids, they could then replant seeds from their own harvests instead of purchasing fresh seed each year. The need to purchase fresh seed has prevented many small farmers from using improved hybrid varieties. They could save seed of their best plants for use the following cycle. Selection of superior, locally-adapted varieties would be enhanced. Apomixis would also allow propagation through seed of crops that are currently vegetatively propagated such as cassava, potato, sweet potato and yams. REF