It appears very likely that DNA marker-assisted breeding for a range of traits—particularly to control diseases and pests, and overcome abiotic stresses—is the second most important application of agrobiotechnology in the mid-term in Africa. Once biosafety laws and appropriate regulatory frameworks and systems are enacted in order to ensure food safety and minimise human health risks and environmental hazards, transgenic crops can be added to the tool-kit of plant breeders working in that region.
The International Center for Agricultural Research in Dry Areas (ICARDA) began operations in Aleppo, Syria, in 1977. The ICARDA mandate covered dry areas in West Asia and North Africa (WANA). The WANA region includes the primary centres of diversity of the ICARDA-mandated crop species: barley, lentils and broad beans (global mandate), and wheat, chickpea and a number of forage species [regional mandate, in collaboration with the International Maize and Wheat Improvement Center (CIMMYT) for wheat and the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) for chickpea].
In the ICARDA Medium-Term Plan for 1990–94, it was stated that, although food self-sufficiency would prove impossible during the 20th century in the WANA region, self-reliance for food should be enhanced through a combination of new technology, better farm practices, more favourable government policies and a more rational land-use pattern. While acknowledging that major increase in food production would come from lowlands with over 350 mm of rainfall annually, ICARDA focused its work on the highlands and driest areas.
A strategy has been developed for integrating biotechnologies into the ICARDA crop-enhancement activities, with a view of providing the National Agricultural Research Systems with well-targeted biotic and abiotic stress-tolerant cultivars and genetic stocks, through the evaluation, adaptation and application of novel genome analysis techniques (DNA marker technology). This approach is applied to crops as well as to the corresponding pathogens, viruses and pests, and should ultimately lead to a more efficient and effective use of existing genetic variability in the ICARDA-mandated crops. Genome analysis also allows for a better estimation of the diversity in these crops, and helps to improve management of the germplasm collections. In cases where insufficient genetic variability exists in the cultivated gene pool, wide crossing with the help of tissue-culture techniques is being explored to bridge species barriers. Double haploid techniques are used to achieve, in a short time, the homozygous state of segregants for fast trait evaluation and selection. Double haploid lines are also considered a useful material for DNA-marker linkage analysis. This strategy was incorporated within ICARDA's Medium-Term Plan for 1994–98 (Sasson, 2000).
While genetic transformation of broad bean (Vicia faba) is difficult to achieve, producing herbicide-resistant broad bean would allow the farmers to better control the invasion of their fields by the Orobanchae weeds (Baum et al., 2002).
With respect to chickpea (Cicer arietinum), genetic transformation aims at producing lines resistant to the blight caused by Ascochyta. Chickpea is cultivated on 11 247 723 ha (FAO Statistics, 1998) worldwide and its production reaches 8 829 095 tons, the average yield being 785 kg/ha. The yield range is 500 kg/ha (Algeria) to 1 800 kg/ha (Egypt). The Ascochyta blight is the most devastating disease of chickpea; the fungal pathogen is highly variable, at least three to six races have been identified; there are limited genetic resources for resistance in the chickpea gene-pool. Fertile transgenic Kabuli-/desi-type chickpea lines have been obtained by the ICARDA scientists, using Agrobacterium-mediated transformation of decapitated zygotic embryos and npt-II/pat as selectable markers. Other genetic constructs will be introduced, followed by the assessment of the resistance to the blight by the GM lines (Baum et al., 2002).
Fertile transgenic lentil (Lens culinaris) lines have also been obtained at ICARDA, using a transformation system developed at the Cooperative Research Centre (CRC) for Mediterranean Agriculture (CLIMA, based in Western Australia) and transferred to the WANA region (Baum et al., 2002).
Wide crossing in wheat and barley has been carried out in collaboration with the University of Cordoba, Spain. The transfer of desirable genes from wild species of Aegilops was carried out at ICARDA as well as in collaboration with the University of Tuscia, Viterbo. Interspecific and intergeneric hybridisation in winter cereals aims to transfer genes of abiotic stress tolerance such as drought, cold, heat and salinity from wild types to cultivated forms by expanding the genetic base against diseases, improving the quality and total biomass of Triticum and Hordeum in moisture-stressed areas and providing specific genetic stocks to national programmes for use in their breeding programmes (Sasson, 2000).
In the case of barley and wheat, following anther culture, inter-specific crosses and embryo rescue, the first double haploid lines were tested under field conditions by the early 1990s. The bulbosum technique was used for this purpose. Hordeum bulbosum is a wild barley species found throughout WANA; it can be crossed with wheat and barley (for barley only in the diploid form); however, after crossing, the bulbosum chromosomes are eliminated and the young embryo is cultured to produce haploids. After selection against biotic and abiotic stresses, double haploids are produced. These techniques could skip a number of intermediary breeding generations (Sasson, 2000).
An ovule-embryo rescue technique has been developed in order to cross the cultivated lentil species, Lens culinaris, with Lens nigricans, a wild species adapted to dry environments (Sasson, 2000).
With cooperation of the institutions involved in the North American Barley Genome Mapping Network Project, ICARDA is developing RFLP markers for barley breeding in low-rainfall environments. This would allow a more efficient and accurate selection of drought-tolerant barley germplasm. Drought tolerance is not a single trait, but the collective result of many traits of a plant which interact with each other positively or negatively. RFLP markers could be used for the identification and selection of single-gene traits associated with drought tolerance (such as osmotic adjustment, photoperiodic response in wheat, water-use efficiency). These were the main findings of a technical study carried out at the request of the Dutch Government's Directorate General for International Cooperation. Another project supported by the German Agency for Technical Cooperation (GTZ) aims to develop molecular markers (RFLP and RAPD/PCR) for barley breeding, in order to effectively select disease-resistant barley germplasm (Sasson, 2000).
The Centre d'étude regional pour l'amélioration de l'adaptation à la sécheresse (CERAAS, Regional Centre for Studies on the Improvement of Plant Adaptation to Drought) was set up in 1982 as a partnership between the Institut sénégalais de recherches agricoles (ISRA, Senegalese Institute for Agricultural Research, Dakar, Senegal), the French CIRAD and Universities of Paris VII and XII, with a view of improving and/or stabilising groundnut production in Senegal. In 1987, the Conference of African Agricultural Research Executives for West and Central Africa (CORAF/WECARD) made CERAAS a regional centre under its umbrella. Nowadays, CERAAS receives funds from the European Commission, other development investors and staff secondment from CIRAD.
CERAAS' general objective is to develop crop cultivars adapted to drought and provide methods of analysis and decision-making tools which will improve agricultural production in arid and semi-arid zones. CERAAS researchers are investigating the mechanisms which allow cowpea (Vigna unguiculata) to adapt to drought and they are trying to map the genes associated with this trait. They are also in the process of mapping cowpea population segregating for drought tolerance with the aim of identifying genetic markers associated with this trait. Micro-satellite markers are being used for this research (Ortiz, 2002).
Among CERAAS' development products, it is worth citing the following:
Creation, in collaboration with the Senegalese Institute for Agricultural Research (ISRA), of a new groundnut variety with a very short life cycle, GC 8-35; this variety will eventually replace the oil-producing variety 55-437, and cultivated in Senegal on about 130 000 ha; the increase in yield estimated for one growing season will reimburse the investments made in research work conducted over 15 years for creating the new variety.
Selection, in collaboration with ISRA, of about 30 groundnut varieties potentially more interesting than varieties GC 8-35 and 55-437 in terms of their production and their drought-resistance capacity; from this improved germplasm, several countries (Burkina Faso, Botswana and Brazil) have selected lines whose agronomic and physiological response to drought are superior to those of local varieties.
Creation and registration of eight sorghum varieties of agricultural importance in Mali, which often cover up to 95% of the area cultivated with sorghum; one of them, Migsor 86-30-03, is particularly resistant to drought and beating down by the wind; it is also used as a genitor in Africa and the USA.
Development of a plant model (AraBHy), coupled with a geographic information system (GIS), that allows the estimation of groundnut production 1 month before harvest; initially developed for groundnut, this model can be adapted to pearl millet, cowpea and soybean, and to other environments, as has been done in Argentina. At the country level, this tool can considerably reduce the costs of identifying agricultural calamity zones and, therefore, contribute to a more effective management of food security.
The IITA (Ibadan, Nigeria), a CGIAR Future Harvest Center, through its Strategic Plan (2001–10), aims at targeting donors' investments to stimulate innovations (e.g., agrobiotechnology) needed to alleviate rural poverty, protect the environment and other natural resources, empower rural peoples and promote economic growth. More specifically, IITA conducts biotechnological research to address the food and income needs of sub-Saharan African countries. Priority is given to genetic transformation of cowpea and plantains/bananas; cassava and maize are a second priority. Molecular mapping of important genes associated with conventional breeding aims at enhancing tolerance or resistance to stresses, e.g. cassava mosaic disease, plant parasitic nematodes or the witchweed Striga. Priority is also given to DNA marker-assisted selection of plantain/banana, cassava and cowpea, whereas cocoa, maize and yams, in which DNA maps are also available, are second tier crops. IITA may also benefit from research advances in the genomics of soybeans, a major legume, also a model crop system. Gene discovery and cloning of functional DNA elements such as promoters will provide non-proprietary tools needed for genetic transformation.
IITA transfers, where appropriate and in collaboration with overseas partners and within the continent, biotechnological products from the laboratory to the market. One well-known example is micropropagation and clonal multiplication of vegetatively propagated crops. Another example is the assistance provided to the emerging private sector to use DNA fingerprinting of cultivars to protect proprietary rights, or to use molecular mapping for identifying new genes relevant to end-user needs.
IITA serves as a platform for technology transfer between overseas advanced research institutes and sub-Saharan African countries. By the end of 2002, 10 internationally-recruited staff were working on biotechnology at IITA laboratories in Cotonou (Benin), Ibadan (Nigeria), Namulonge (Uganda) and Yaounde (Cameroon), as well as at the high throughput genomics laboratory of the International Livestock Research Institute (ILRI) in Nairobi.
Finally, IITA enhances the capacity of national selected partners in order to apply and monitor biotechnology, e.g. IITA, together with research-for-development partners and development investors, is working towards the approval of biosafety guidelines concerning GMOs, as has been achieved in Nigeria (Ortiz, 2001).
Partnerships with African researchers are reinforced through group and individual training. For instance, with funding from the USDA and USAID, IITA initiated a project for developing and updating skills of biotechnologists from Nigeria and Ghana to address farmers' needs. This project deals with biotechnological capacity building and research, adapts available approaches for developing or strengthening bioinformatics databases; and conducts research on potential risks associated with the introduction of transgenic crops into Africa (Ortiz, 2002b).
In 2002, a visiting scientist assessed the status of, and needs for agrobiotechnology in West and Central Africa (thanks to a USAID grant given to IITA). This assessment will lead to the design of a regional agrobiotechnology programme for West and Central Africa. In the last quarter of 2002, IITA initiated, as implementing agency, the Nigerian Biotechnology Programme with an agenda driven by the Nigerian stakeholders and funding from the USAID and the Nigerian Government. This programme includes capacity building on genetic transformation—including testing biosafety guidelines, crop genomics and livestock biotechnology, as well as creating unbiased public awareness of biotechnology in Nigeria (Ortiz, 2002b).