| Among the abiotic stresses that limit plant growth and productivity, drought is the most complex and devastating on a global scale. With expected frequent, severe, and widespread droughts, crops with greater ability to adapt to reduced water use are needed to cope with the changing environment and more severe drought conditions.;Studies were designed to evaluate an inter-gene pool recombinant inbred line (RIL) bean population from a cross of SEA5 and CAL96 for drought resistance and identify quantitative trait loci (QTL) linked to drought resistance in the field, identify shoot traits associated with drought resistance in bean seedlings, and identify factors influencing regeneration and Agrobacterium tumefaciens-mediated transformation of common bean.;In the field, the SEA5/CAL96 population was evaluated for drought tolerance under rainfed and irrigated conditions in Rwanda and Colombia. Drought adaptation variables such as phenology, partitioning indices, seed yield, and yield components were evaluated. Based on a combination of partitioning indices, seed yield, and seed size, lines combining higher drought resistance than the susceptible parent with medium seed size were identified. These lines will be used to facilitate future enhancement of drought tolerance in Andean beans in Rwanda.;A genetic map of the SEA5/CAL96 population spanning 1031 cM was constructed using 92 SSR and 12 InDel markers. QTL analysis identified 41 QTL across environments. Some of these QTL mapped near previously reported QTL in different studies while others were specific to this study. A major QTL for yield and yield per day accounting for 37% of phenotypic variation was identified on chromosome Pv11. This QTL is linked to QTL associated with 100-seed weight which would facilitate to select simultaneously for yield and seed size.;Ten bean genotypes were evaluated for shoot traits related to drought resistance at seedling stage under restricted root growth conditions in the greenhouse. After withholding watering, plants were scored for wilting, unifoliate senescence, maintenance of stem greenness, recovery, and the capacity to set pods. Stem greenness and reduced wilting were found to enhance recovery from an extended period of drought in common bean seedlings.;Various factors including media, genotypes, explants, A. tumefaciens strains, and transformation methods were assessed in regeneration and transformation studies of common bean. Bean embryo axes were more regenerable than other explants and there was no medium capable of inducing regeneration of non meristematic bean cells. Three strains of A. tumefaciens were efficient in gene delivery depending on co-cultivation time, explant type, and bean genotype. Agro-infiltration seemed to enhance gene delivery in common bean. |
