Advances in common bean improvement: Some case histories with broader applications

Scientists in developing countries and the U.S. have made significant advances in breeding and genetics for multiple disease and stress resistance, and increased yield in common bean (Phaseolus vulgaris L.). It is an important commercial crop in many areas of the world, as well as a staple food crop for the poor in Latin American and East Africa. This paper will, through specific case histories, review some highlights of the work that led to these advances in the U.S. and other countries. Implications for bean breeders of the domestication genetic syndrome, two major gene pools, and breeding pyramid will be first outlined. Four case histories will be examined: 1) architype breeding to improve yield per se or to provide a canopy avoidance mechanism to reduce losses due to white mold disease; 2) classical and molecular pyramiding of major genes for resistance to anthracnose, bean common mosaic virus, rust, and QTL for resistance to common bacterial blight to provide for enhanced durability of resistance; 3) the mapping of anthracnose and rust resistance gene clusters, and associations with the co-evolution of both pathogens in the two gene pools; and 4) approaches to alleviate biotic and abiotic stresses that limit bean production in Latin America. Some major challenges in bean improvement for the future will be presented.