Progress and Challenges for Improvement of African Crops.

The development of new varieties of wheat and rice having enhanced resistance to disease and lodging and good response to fertilizers was key to the success of the first Green Revolution in Asia.  While Africa did not share in that success, since the 1980s there has been some slow and steady success in development and uptake of improved varieties of crops that are most suited to the complex agroecologies and preferences of its inhabitants.    Yet these successes have not kept pace with demand, and the African continent remains the one area where crop yield per capita has not significantly increased.   Significant advances in inbred line development for tropical maize has gone hand-in-hand with strengthening of the private sector seed businesses and enhanced uptake of newer, better adapted and higher yielding hybrid varieties.   Recent work developing hybrid guinea sorghum in western Africa and hybrid pigeon pea in India seems promising, yet Africa lags behind the rest of the world in development and uptake of hybrid crops beyond maize.   Breeding successes for legumes include development of a number of climbing bean varieties and creation of new large-seeded, wilt resistant varieties of pigeon pea. Development of early-maturing varieties of several crops is contributing to ability to double crop and resist drought.    Distribution of cassava resistant to mosaic virus disease has had significant impact but is being threatened by emergence of resistance-breaking DNA satellites and the spread of brown streak virus. One critical weakness remains the lack of inbred lines for critical crops like cassava and sweetpotato that remain highly heterozygous and recalcitrant to conventional breeding approaches.  Breeders trained in classic approaches will always be critical for intensive phenotyping and interaction on the ground to understand the needs of farmers.   However, the incredible increase in speed and decrease in cost of DNA sequencing has already changed the face of breeding in the developed world.  For this to occur in Africa will require a whole new cadre of breeders trained and committed to use of such technologies, centralized facilities for marker development and analysis, an intensive commitment to correlate a broad range of phenotypic data with genomic information, and, most challenging of all, provision of adequate resources to make the transition.   Finally, development and deployment of GM crops is at a critical tipping point in Africa where success will most likely depend upon the involvement and support for local scientists in the process.