Stephen Beebe

Stephen Beebe received his B.Sc. degree in horticulture in 1974 from Iowa State University, and M.Sc. and Ph.D. degrees in Plant Breeding-Plant Genetics from the University of Wisconsin in 1976 and 1978, respectively. He has spent his career in the International Center for Tropical Agriculture (CIAT) in Cali, Colombia as a breeder of common bean (Phaseolus vulgaris), initiating in 1977 as a PhD student, and serving both Latin America and East and southern Africa.

He has worked on disease and pest resistance, with emphasis early in his career on Xanthomonas bacterial blight, bean golden yellow mosaic virus, and bean pod weevil (Apion godmani), later adding angular leaf spot, anthracnose, and a range of other insect pests. His experience in nutritional quality focused on biofortification of beans, initiating with an exploratory workshop in 1994 that eventually led to the establishment of the HarvestPlus program. Common bean was chosen as a target for raising concentrations of iron and zinc in grain. Initial sources of high iron emerged from a core collection of common bean, where high mineral sources proved to be inter-gene pool accessions. Much later interspecific crosses with the tertiary gene pool offered sources for much higher levels, given their evolution in iron-poor alkaline soils in Mexico and southwestern United States. He has worked more intensively in the past decade on abiotic stress: tolerance to drought, aluminum, and low soil phosphorus, in particular seeking tolerance to combined stresses as a key to improving bean yields in the tropics.

A key to breeding efforts has been an understanding of the physiology of the Phaseolus genus, which has species originating in environments ranging from tropical rain forests to arid deserts. Across such a range of origins, issues of partitioning emerge as critical for adaptation of wild species and ancestors, whereby vegetative vigor and climbing habits assure survival in moist, competitive environments, while rapid partitioning to seed development is required in arid or semi-arid environments. Interspecific crosses with the tertiary gene pool (P. acutifolius and other species) have been facilitated by the discovery of bridging genotypes that permit introgression of traits to common bean on a much wider scale. The unique evolutionary history of these species offers opportunities for improvement of bean for climate resilience, pest resistance, and yield potential.