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Genetic Modification ~ The 'Pro' Position

Author: Emeritus Professor Jennifer A Thomson - Department of Molecular and Cell Biology, UCT

( Article Type: Opinion )

Genetically modified (GM) crops are those in which genes from another species have been inserted to express a particular trait, which the original crop lacked. Genetic modification differs from traditional breeding in that GM crops may contain genes from a completely different organism. The major GM crops currently in commercial use worldwide are herbicide tolerant soybean, insect resistant maize and cotton, with smaller amounts of cotton and maize carrying both herbicide tolerance and insect resistance. In 2009 China approved the commercialization of insect resistant rice and phytase maize. The latter allows the degradation of the phytic acid normally locked into maize and releases it in an edible form which improves animal nutrition. Papayas (pawpaws) resistant to Papaya ringspot virus virtually saved this crop in Hawaii.

GM crops in development and field testing stages include:
• Vitamin enriched rice and sorghum
• Insect resistant cowpeas, mainly for use in west Africa
• Drought tolerant maize
• Insect resistant potatoes
• Maize resistant to the African-endemic Maize streak virus

The year 2010 marked the 15th anniversary of the commercialization of GM crops. In 2009 a record 14 million small and large scale farmers in 25 countries planted 134 million hectares (330 million acres), an increase of 7% or 9 million hectares over 2008. In South Africa approximately 79% of the 2009 white maize crop and 77% of the yellow maize crop was GM, predominantly insect resistant varieties. Herbicide tolerant soybean accounted for 85% of the total crop. Cotton production is generally down in the country due to a variety of factors but of the planted crop more than 95% were insect resistant GM varieties. South Africa is estimated to have benefited by US$507 million over the period 1998 to 2008 due to a combination of decreased use of insecticides, increased yields and more effective use of herbicides. Some of the ‘knock-on’ advantages of GM crops are with both herbicide tolerant and insect resistant plants. As spraying of herbicide can now be at the discretion of the farmer and does not have to occur before the crop is planted, there has been a marked decrease in the use of tilling. This ‘low till’ farming practice results in a decrease in the loss of topsoil and resultant soil erosion. Moreover, the herbicide glyphosate, which is now used, is less toxic to the environment than many of the previously used weed killers. In addition, because insect-resistant maize does not suffer from insect damage, it is more resistant to post-harvest fungal infection. Many of these highly toxic compounds, known as mycotoxins, can result in diseases such as toxic hepatitis and oesophageal cancer.

Concerns have been raised that herbicide tolerant crops could result in the formation of superweeds and that insect resistant crops could lead to the development of insect resistance. Although to date no evidence of this has been found, it is still important to use sound agricultural practices to mitigate against this happening. For instance, farmers must plant a certain percentage of non-GM crops among their insect resistant varieties to decrease the chances that insects will develop resistance. Concerns have also been raised that the use of GM crops will result in a decrease in biodiversity. However, the opposite may well be true. It is much easier for plant breeders to introduce a single gene, giving a desired trait, into many different crop varieties than it is with traits resulting from conventional breeding.## Another concern is that foods derived from GM crops may not be safe for human and animal consumption. No evidence, derived from years of rigorous testing, has been found for the lack of food safety. In fact, while conventional foods are not tested for food safety, only GM foods are. Thus we actually know more about the safety of foods derived from GM crops than about any other food we eat. All countries wishing to test or commercialise GM crops are required to have in place biosafety regulations to ensure the correct use of such crops. In South Africa the GMO (Genetically Modified Organisms) Act was passed in 1997 and modified in 2010. It is administered by the National Department of Agriculture and has on its Executive Council members of all the government departments involved, e.g. Health, Environment, Science and Technology, Trade and Industry. All applications for imports, field trials and commercial releases have to be subjected to scrutiny by panels of experts before permission is given or withheld. In Africa commercial releases have only been approved in South Africa, Burkina Faso and Egypt. Countries where field trials are allowed include Kenya, Malawi, Nigeria, Tanzania and Uganda

Despite opposition to GM crops, most notably in Europe, developing countries are adopting the technology as part of the answer to sustainable food production. It will be important to monitor the use of GM crops on a case-by-case basis, but in most resource-poor countries the benefits are likely to outweigh any possible risks.