An Integrated Program to Accelerate Breeding of Resilient, More Productive Beans for Smallholder Farmers

Goals / Objectives
Common bean (Phaseolus vulgaris) provides essential nutrients and ecosystem services to developing regions of Latin America and of Eastern and Southern Africa. Bean yields in these regions are severely reduced by abiotic stresses, especially drought, heat, and low soil fertility. These constraints are intensifying over time because of soil degradation, population pressure and climate change. Past breeding for stress-tolerant beans has relied primarily on yield trials, which are imprecise and costly and which only sample a limited range of environments and management options in a given season. Recent developments in crop physiology, phenotyping platforms, and genomic tools present opportunities to greatly accelerate breeding progress by targeting specific traits and integrating them into conventional breeding efforts via marker-assisted breeding, trait phenotyping, and trait-based selection. This project seeks to integrate these new tools and develop new bean lines with greater tolerance to drought and heat stress in Central America and in Eastern and Southern Africa. The project integrates multiple mutually supportive efforts to accelerate bean breeding.

Project Methods
Phenomics: Novel phenotyping platforms will be used to characterize bean germplasm for resistance traits, identify new sources of tolerance, and guide recurrent selection programs. For drought tolerance, we will focus on root traits that improve water uptake from drying soil, grain filling under stress and optimize phenology for drought avoidance. For heat tolerance, we will emphasize stress affecting reproductive processes. Genomics: Next generation genomics tools will be deployed to identify major genes conferring greater drought and heat tolerance. The tools include the recently completed sequence of the bean genome, highly saturated marker chips, genotype-by-sequencing methods, and association mapping of specific tolerance traits identified by the phenomics module. Breeding: A coordinated network of Bean Abiotic Stress Evaluation (BASE) trials will be initiated at sites in the USA, Mozambique, Malawi, Zambia, Colombia and Honduras to screen Andean and Mesoamerican bean germplasm. Heat and drought tolerance of Tepary bean (Phaseolus acutifolius) will be leveraged through interspecific crosses. Germplasm will include supportive traits of root rot resistance, tolerance to low soil P, excellent BNF, and high seed Fe content. The breeding strategy will focus on specific tolerance traits and markers for them.