Genetic And Phenotypic Architecture Of Root Phenotypes In Common Bean

Phaseolus species are globally important food security crops. Common bean production is limited by abiotic and biotic stresses such as drought, low soil fertility, and disease. Several root phenotypes promote topsoil foraging and therefore phosphorus capture, while others improve rooting depth and water capture. In this work, I compared root phenotypes of wild and domesticated taxa. I found that wild and domesticated taxa differ in architectural and anatomical phenotypes. Wild Phaseolus taxa displayed greater metaxylem vessel number and root cross-sectional area and greater variation for root hair length and density which may be exploited in breeding programs to improve drought and phosphorus acquisition. I extended the work to explore the root phenotypes of the Andean and Mesoamerican gene pools. In this study, I assess the value of hybridization between gene pools to optimize root phenotypes for edaphic stress tolerance. I found transgressive segregation for root phenotypes, including basal root whorl number, basal root number, root hair density, root hair length, yield and biomass under low P in progeny. These results demonstrate the potential value of hybridization between gene pools to develop improved varieties with root phenotypes conferring enhanced stress tolerance. However, studying the root system is essential to know the difference in root phenotypes between gene pools and among and within the diversity panels. In my study, I phenotyped root system of three diversity panels, the Andean, Mesoamerican and Durango. I found genetic and phenotypic and variation among the three diversity panels. A locus was discovered that is associated with three important root phenotypes in all diversity panels. I found that genome-wide association analysis revealed contrasting control for root hair length and density among diversity panels and some variation associated with the experimental system. The genomic regions identified could be used by breeders in marker-assisted selection for root phenotypes to develop better stress tolerance genotypes. To sum up, improving root phenotypes for abiotic stress tolerance can be a solution for enhancing bean production in poor soils.