Empowering Biotechnology in Africa through Effective Technology Transfer: the Success Story of Cassava Biotechnology
Hervé Vanderschuren, Plant Biotechnology Laboratory, Biology Department, ETH Zurich, 8092 Zürich, Switzerland. E-mail: hvanderschuren [at] ethz [dot] ch
Over the last decade, cassava has gained increasing importance in tropical countries because of a growing demand for food, feed and industrial starch, as well as biofuel production (Jansson et al., 2009; Sriroth et al., 2010). Cassava is attractive for farmers because it is considered to be amongst the most resilient crops in the tropics given its capacity to thrive in harsh environments and produce good yields with limited input. However, average cassava yields in the tropics reach barely 20% of the yields obtained under optimal crop management (El-Sharkawy, 2004; FAOSTAT, 2012). Average yield on the African continent is estimated to be around 10 tons per ha, while recent reports have demonstrated that 50-60 tons per ha can be achieved using appropriate crop management practices, fertilization and improved germplasm (Fermont et al., 2009).
Besides the necessity to optimize and promote good agronomical practices for cassava, development of improved accessions is also key to increasing cassava yield. In recent decades, cassava improvement has relied heavily on classical breeding performed by international and national research centres in countries where cassava is a major staple crop. Despite generation of good cassava cultivars and elite lines, introgression of improved traits in cassava has remained a tedious and time-consuming task, because of its high heterozygosity and its long life-cycle (Ceballos et al., 2004). For some traits, the availability of molecular markers can partially circumvent the limitations associated with classical breeding and facilitate stacking of multiple desired traits (Rudi et al., 2010). In this context, genetic transformation has emerged as a powerful tool to produce improved cassava in a time-efficient manner, to generate new traits not available in the cassava germplasm as well as to combine multiple improved traits easily in selected farmer-preferred cassava cultivars.
The Emergence of Cassava Biotechnology
Following the development of the first transgenic plants in the 1980s, the cassava community has initiated the implementation of procedures for cassava genetic transformation. Cassava was considered as recalcitrant to transformation and therefore the coordinated efforts of scientists from several teams in Europe, USA and the International Centre for Tropical Agriculture (CIAT) were necessary to establish the production of the first transgenic cassava. Successful cassava transformation procedures were simultaneously published by two Western laboratories for the first time in 1996 (Li et al., 1996, Schopke et al., 1996). Production of transgenic cassava, being recalcitrant to transformation, was achieved at low rates of efficiency and only with a cassava cultivar amenable to genetic transformation in well-equipped laboratories. It was wisely pointed out in an editorial published in Nature Biotechnology that transfer of the technology to countries where transgenic cassava will be of practical interest would represent a challenging and important objective for the cassava biotechnology community (Vasil, 2010).
Development of Cassava Biotechnology in Africa
To make transgenic cassava available for Africa, two options, not mutually exclusive, are possible: (a) the production of transgenic cassava in laboratories outside Africa and importation of transgenic lines into African countries where legislation for genetically modified crops has been implemented, (b) the implementation of the cassava transformation technology in African laboratories. The first confined field trials of transgenic cassava in Africa have been performed with transgenics produced in Western laboratories (Sayre et al., 2011). The initial transfer and field trial of these lines in Africa contributes to build local expertise in the handling and assessment of transgenic cassava. However, recent opinion studies reveal that promotion and acceptance of transgenic crops in Africa will also require local capacity to develop transgenic crops (Ezezika et al., 2012). The latter is essential for self-determination of the African continent, a theme long defended by African leaders (Sankhara, 1987; Mbeki, 1998).
Transfer of cassava genetic transformation technology to African laboratories faces several challenges. Firstly, protocols for genetic transformation of cassava have been developed in laboratories under optimal conditions. Because many transformation procedures have low efficiencies, their implementation in laboratories with suboptimal conditions and equipment can make them inadequate for stable and efficient cassava genetic transformation. Secondly, procedures have been mostly developed for model cassava cultivars amenable to genetic transformation. The use of model cultivars has been particularly instrumental for proof-of-concept research (Liu et al., 2011). However, African laboratories are equally interested in establishing cassava transformation for both proof-of-concept research and product development. Therefore, protocols also need to be adapted to allow efficient transformation of farmer-preferred cassava cultivars.
Development of robust transformation protocols has been key for technology transfer to African laboratories (Bull et al., 2011). Because genetic transformation of cassava necessitates production of substantial amounts of in vitro tissues suitable for transformation, procedures limiting sterile handling of cassava tissue such as that developed at ETH Zurich (Bull et al., 2009; Niklaus et al., 2011) have helped to reduce rates of fungal and bacterial contamination. The latter is particularly relevant for implementation in laboratory environments prone to high contamination rates of plant tissue cultures. Other parameters such as water quality, power cuts and consumable supplies can further reduce transformation efficiencies and regeneration rates. Robust transformation protocols with high transformation and regeneration efficiency rates under optimal conditions are also more suitable for implementation in suboptimal conditions because any reduction in those rates is less likely to annihilate the regeneration of transgenic cassava. The use of a model cassava accession, which displays higher transformation efficiencies over other cultivars, represents a valuable implementation tool. It allows training of local scientists with a well-characterized cultivar routinely used in other laboratories, which eases troubleshooting at each step of the transformation procedure. Robust protocols are also more suitable for adaptation to transformation of farmer-preferred cassava accessions (Zainuddin, I., Schlegel, K., Gruissem, W. and Vanderschuren, H. ‘Transformation procedure for the production of transgenic farmer-preferred cassava cultivars’, manuscript in revision). Following establishment and stabilization of genetic transformation platforms in their institutions, African scientists must identify cassava cultivars that are the most relevant for their agrosystems and adapt the model cultivar transformation procedure to these cultivars (Chetty et al., 2012).
Strategies for Technology Transfer and Maintenance
Importantly, the implementation of genetic transformation technologies needs to be coupled to capacity-building strategies in order to make these newly transferred technologies sustainable. At least two distinct strategies can be elaborated for capacity building: (a) training of local scientists in Africa based around the organization of regular hands-on workshops with experts in the field; (b) education and training of African scientists in laboratories where cassava transformation is routinely performed. Both strategies facilitate technology transfer through building local expertise. However, training primarily organized in African laboratories helps identify on-site limitations and problems, and is therefore sometimes more appropriate for rapid troubleshooting (Chetty et al., 2012). Both capacity-building strategies have been used to establish cassava genetic transformation platforms at Biosciences eastern and central Africa (BecA, Nairobi), University of Witwatersrand (Johannesburg) and Mikocheni Agricultural Research Institute (MARI, Dar es Salaam) using transformation technologies developed at ETH Zurich (Bull et al., 2009; Chetty et al., 2012). The success of technology transfer also depended on other parameters such as laboratory and project management, as well as resource availability to maintain the established technology.
Figure 1. Cassava genetic transformation using robust transformation procedure in Dar es Salaam (Photo: H. Vanderschuren)
Technology transfer cannot be a goal per se. The underlying objective of technology transfer to Africa is to enable local scientists to perform high quality research and to develop agbiotech products that meet local needs. Therefore, it is essential that technology transfer projects build on lasting interest and demand from local institutions. Competent technical and management staff need to be actively associated with transfer activities. Importantly, local staff should also elaborate research and development projects driving the need for long-term maintenance of the technology in African laboratories where it has been established.
Future Challenges for Production and Adoption of Transgenic Cassava in Africa
In order to be supported and maintained, technologies eventually need to have a positive impact on African society. This renders agbiotech technologies heavily dependent on the development of a national biosafety framework to test and implement agbiotech products in African countries (Paarlberg, 2010). Local product development, tangible benefits for farmers, distrust of the private sector and legal framework are key parameters influencing agbiotech adoption and development in sub-Saharan Africa (Ezezika et al., 2012). Therefore, sustainable development and adoption of transgenic cassava in Africa cannot occur if those parameters are neglected. It will imply: (a) genuine cassava technology transfer enabling African scientists to develop local products and solutions, (b) development of transgenic farmer-preferred cassava with improved traits beneficial for farmers and local communities, (c) careful selection of public-private R&D partnerships associated with positive perception of the technology in society, and (d) development of a legal biosafety framework and genetically modified (GM) crop regulation by African officials. The simultaneous combination of these activities should be the modus operandi to overcome opposition to GM crops and exploit the full potential of GM cassava for Africa. The first production of a transgenic industry-preferred cassava cultivar by an African laboratory (Chetty et al., 2012) should pave the way for African self-determination in cassava biotechnology research.
Figure 2. Virus resistance evaluation of locally produced transgenic cassava in Johannesburg (Photo: H. Vanderschuren)
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