The Use of GM Crops in Developing Countries
Current and potential uses of GM crops in developing countries
3.1 In the following section we provide a brief introduction to the concept of genetic modification in the context of contemporary plant breeding.1 We then describe the traits which researchers are hoping to achieve by means of genetic modification and give an overview of the types of GM crops that are currently grown in commercial agriculture worldwide. Finally, we present eight case studies, which describe in more detail current and potential uses of GM crops in commercial and subsistence agriculture in developing countries. Research on GM crops in the context of conventional plant breeding 3.2 Following the rediscovery of Mendel’s Laws in 1900, selective plant breeding has made dramatic progress. Together with new agricultural methods, the application of this knowledge has contributed to a doubling of global food production over the past 50 years. In parallel, plant breeders have assimilated a variety of new technologies which have been used in both developed and developing countries. Many of these are aided by applications of biotechnology. Examples include:
- double haploids, where pure breeding lines can be made in a single step;
- mutation breeding, where new variations can be generated by irradiation or by chemical treatments;
- F1 hybrids, where farmers can benefit from the expression of hybrid vigour (plants grow faster, have higher yields and are more resistant to environmental stresses as a result of selecting parental varieties with specific genetic differences); and
- tissue culture, a process which has been particularly beneficial to tens of thousands of small-scale farmers in developing countries (it allows whole, often virus free, plants to grow from a single cell in an artificial medium).2
3.3 Marker-aided selection (MAS) enables plant breeders to select a piece of DNA that is associated with a particular trait, thereby avoiding time-consuming and expensive tests to select the ideal parent or offspring. MAS can significantly speed up the plant breeding process and a new variety can be produced in approximately four to six generations, rather than in ten. MAS is particularly useful for breeding crops with resistance to moisture-stress for environments with an irregular supply of water. To achieve this characteristic, a variety of different traits would have to be selected and MAS allows plants that express these different traits to be rapidly identified. The technique is also useful in research which aims to interbreed maize varieties that are already resistant to moisture-stress with African varieties of the crop, which are otherwise well adapted.3
Footnotes1 Further information can be found in Chapter 2 of the 1999 Report.
2 Successful applications of this technique include, for example, the production of improved and disease-free banana seedlings which have been made available to small-scale farmers in Kenya, see Wambugu FM and Kiome RM (2001) The Benefits of Biotechnology for Small-Scale Banana Producers in Kenya International Service for the Acquisition of Agri-biotech Applications (ISAAA) Brief No. 22 (Ithaca, NY: ISAAA). Another major application of tissue culture is the embryo rescue technique which allowed researchers to cross the particularly high-yielding Asian rice Oryza sativa with an African rice variety that was exceptionally competitive with weeds, resistant to moisture-stress and disease resistant, see Jones MP (1999) Basic breeding strategies for high yield rice varieties at WARDA, Jpn J Crop Sci 67: 133–6.
3 Ribaut J-M et al. (2002) Use of molecular markers in plant breeding: drought tolerance improvement in tropical maize, in Quantitative Genetics, Genomics and Plant Breeding, Kang MS, Editor (Wallingford, UK: CABI Publishing), pp85–99.