The Use of GM Crops in Developing Countries
GM crops relevant to developing countries
3.18 Most commonly, the improvement of plants aims to increase the yield or quality of crops. Yield is influenced by many factors including pests, diseases, soil conditions, or abiotic stresses15 which stem from unfavourable climatic conditions. Significant improvements can often be achieved by means of irrigation, the application of insecticides or pesticides and the addition of fertiliser. However, most of these interventions are expensive, particularly for small-scale farmers in developing countries.16 The use of genetic modification provides plant breeders with new opportunities to produce crops that are protected from environmental stresses and attacks from pathogens and insects. The following list gives examples of traits that researchers aim to develop by means of genetic modification. Some of these are still in early stages of development, while others have been achieved more recently in the laboratory setting. A few are in field trials, or can already be found in crops used by farmers.
In some cases the traits can be arrived at by conventional breeding, while others are achievable only by genetic modification (see also Appendix 3).
- Herbicide tolerance A transgene confers tolerance to a specific herbicide. This trait allows farmers to apply a herbicide which acts on a wide range of weeds while not affecting the modified crop. Herbicide tolerance is currently the most commonly used GM trait worldwide, for example in soybean, maize, cotton and oil seed rape (see case study 7). Herbicide tolerant crops are mainly grown in developed countries with the primary aim of reducing applications of herbicides. The trait has also been achieved using other methods, particularly mutation breeding and gene transfer from wild relatives.
- Insect/pest resistance A transgene produces toxins to specific insects that feed on the crop. Such genes have been widely used and are already leading to substantial reductions in the use of pesticides and insecticides. Insect-resistant cotton, maize and potato varieties are being grown in both developed and developing countries (see case study 1 on Bt cotton).
- Bacterial, fungal and viral resistance Here a transgene makes crops resistant to biotic stresses such as plant pathogens which often reduce yields substantially. Examples of crops in which these traits are being introduced include coffee, bananas, cassava, potato, sweet potato, beans, wheat, papaya, squash and melon (see case Studies 5 and 6 on sweet potatoes and bananas). In some cases the transgenes used are genes which occur naturally in the same species.
- Abiotic stress resistance The ability of some plants to survive in harsh climatic or soil conditions is sometimes associated with specific groups of genes. These genes can be isolated and introduced into crops. Such applications promise to be particularly valuable for developing countries, where abiotic stresses such as drought, heat, frost and acidic or salty soils are common. Research on crops such as cotton, coffee, rice, wheat, potato, Brassica, tomato and barley varieties is currently in different stages of completion (see case study 2 on rice that is resistant to moisture-stress).
- Micronutrient enrichment In aiming to prevent malnutrition, transgenes could play a vital role in the provision of vitamins or minerals. GM crops could help to provide people with essential micronutrients through consumption of their main staple crop. Research in this area is currently being undertaken in rice, cassava, millet and potato (see case study 4 on Golden Rice).
3.19 Another application of genetic modification includes the controversial gene use restriction technology (GURT), also known as ‘terminator technology’, which leads to seed sterility (see paragraph 4.18 of this Discussion Paper and paragraphs 2.26 and 4.75 of the 1999 Report).17 Other applications which are either in advanced stages of development or already used in agricultural practice include improved shelf-life of fruit and vegetables, and the use of plants for the production of biopharmaceuticals, such as vaccines (see case study 8).18 There is also a range of traits which are still in relatively early stages of development, but which are nonetheless promising and potentially important. This includes research to enable the transfer of genes conferring apomixis, which is the capacity to produce seeds in the absence of normal sexual reproduction, to crops.19 This application could enable outstanding traits to be perpetuated over generations without farmers needing to buy new seed (see paragraphs 2.23, 2.39 and 3.39 of our 1999 Report). Other research aims to produce GM crops that can be used for the production of bioplastics or biofuels, as substitutes for fossil fuels and their products. It may also be possible to develop nitrogen-fixing cereals; glutenproducing sorghum for bread-making in Africa (currently dependent on imported wheat); and crops with such high tolerance to salinity that salty marsh water can be used for irrigation.20
3.20 We provide in the next section a brief survey on the kinds of GM crops that were grown worldwide in 2002. This is followed by eight case studies which illustrate current and potential benefits and risks associated with the use of GM crops in developing countries.
Footnotes15 Stresses upon a crop may be either biotic or abiotic. Biotic stresses refer to the influence or impact which other living organisms have on a crop. Abiotic stresses usually refer to physical and chemical components of a crop’s environment.
16 For example, the price of urea, a commonly used fertiliser, is US$400 per metric tonne in Western Kenya, US$770 in Malawi and only US$90 in Europe. See Sanchez PA (2002) Soil fertility and hunger in Africa, Science 295: 2019–20. See also Conway G (2003) From the Green Revolution to the Biotechnology Revolution: Food for Poor People in the 21st Century. Speech at the Woodrow Wilson International Center for Scholars Director’s Forum. 12 March 2003. Available: http://www.rockfound.org/documents/566/Conway.pdf, p8. Accessed on: 10 Oct 2003.
17 Companies developing this technology emphasise that its purpose is to allow the control of gene flow, whereas critics claim that the purpose is the control of seed markets, by making the saving of harvested seed for re-sowing in the next season unfeasible.
18 Agriculture and Environment Biotechnology Commission (AEBC) (2002) Looking Ahead - An AEBC Horizon Scan (London: Department of Trade and Industry); GeneWatch (2003) Briefing No. 21 Genetic Modification: The Need for Special Regulation (Derbyshire, UK: GeneWatch).
19 For a review see Chaudhury AM et al. (2001) Control of early seed development, Annu Rev Cell Dev Biol 17: 677–99.
20 See, for example, Mazur B, Krebbers E and Tingey S (1999) Gene discovery and product development for grain quality traits, Science 285: 372–5; AEBC (2002) Looking Ahead - An AEBC Horizon Scan (London: Department of Trade and Industry); Fitzgerald P (2003) Salt-Tolerant GM Wheat, Ground Cover 44 (Grains Research & Development Corporation). Available: http://www.grdc.com.au/growers/gc/gc44/gene_scene.htm. Accessed on: 14 Oct 2003; James C (1999) Global Review of Commercialized Transgenic Crops: 1999 ISAAA Brief No. 12 (Ithaca, NY: ISAAA).