The Use of GM Crops in Developing Countries
Case study 3: Increasing yield in rice by dwarfing
3.43 Another method of increasing crop yields is by the production of dwarf varieties. Shorter plants can make more nutrients available for grain production. The introduction of semidwarfing genes into wheat was one of the primary technical achievements of the Green Revolution in the 1960s and 1970s, contributing to the doubling of wheat yields
worldwide.
The development of the dwarf rice variety IR-8 in 1963 was equally important.61 However, the genes used to reduce height in the two crops were very different. In both cases the farmer could use the improved strength of straw to gain yield because he was able to apply more fertiliser (where he could afford to do so). The wheat variety also had the advantage of increasing yield directly through a greater number of grains in the ear.
3.44 In 1999, a team at the John Innes Centre (JIC) isolated a gene from a common weed (Arabidopsis thaliana) which codes for the same type of dwarfism found in the semi-dwarf wheat varieties used in the Green Revolution. When the gene was introduced into rice, dwarf plants were obtained.62
3.45 Together with their Indian collaborator, researchers at the JIC have introduced the Arabidopsis gene into basmati rice to produce the first dwarf variety. Basmati is commonly grown on the Indian subcontinent, but the plants are usually tall, have weak stems and are highly susceptible to damage by wind and rain. These features frequently lead to considerable yield losses. Previous attempts to reduce the height of the basmati variety while retaining its desirable qualities using conventional breeding methods have resulted in loss of the very characteristics for which it is valued. Field trials will eventually reveal whether the dwarfed basmati rice varieties have higher yields, as is the case with semi dwarf wheat varieties. An important feature of this application of genetic modification is that it contributes both to the improvement of traits and the conservation of biodiversity. The single gene can be inserted with minimal disturbance to the rest of the genetic complement and a multitude of locally well-adapted varieties can simultaneously be conserved and improved.63
Footnotes60 At the International Maize and Wheat Improvement Centre (CIMMYT) in Mexico, trials on moisture-stress resistant wheat plants are currently taking place in experimental greenhouses. See Pellegrineschi A (2003) Drought-resistant GM crops: a
promising future, SciDev.Net 30 Jan 2003. Available:
http://www.scidev.net/dossiers/index.cfm?fuseaction=dossierReadItem&type=3&itemid=5&language=1&dossier=6. Accessed
on: 20 Oct 2003. Other crops resistant to abiotic stress, which are currently at the stage of field trials include frost tolerant potatoes in Bolivia, cold tolerant tomatoes in China, salt tolerant wheat in Egypt, moisture-stress resistant Brassica in India,
and salt and moisture-stress resistant rice in Thailand. See FAO Electronic Forum on Biotechnology in Food and Agriculture
(2002) Background Document to the Conference 8, 13 Nov - 11 Dec 2002 What should be the role and focus of
biotechnology in the agricultural research agendas of developing countries? (FAO UN). Available:
http://www.fao.org/biotech/C8doc.htm. Accessed on: 20 Oct 2003.
61 Dalrymple D (1976) Development and Spread of High Yielding Wheat and Rice in the Less Developed Nations US Dept of Agriculture, Foreign Development Division, Economic Research Service: Foreign Economic Agricultural Report No. 95, p120.
62 Peng J et al. (1999) ‘Green revolution’ genes encode mutant gibberellin response modulators, Nature 400: 256–61.
63 Peng J et al. (1999) ‘Green revolution’ genes encode mutant gibberellin response modulators, Nature 400: 256–61.