Micronutrient malnutrition, particularly iron and zinc affects millions of people around the world. Biofortification (nutrient enhancement in staple crops) has a potential to address micronutrient malnutrition especially for vegetarians and people who heavily rely on plant-based diets. Common bean (Phaseolus vulgaris L.) is the most important food legume crop grown worldwide. It is also an important component of production systems and a major source of protein, fiber, and minerals to millions of people. However, the full genetic potential of common bean to supply iron and zinc to humans is not well understood. Also, genotype x environment interactions and growers’ priority traits for biofortified crops are not adequately studied. Three research objectives were designed to address these knowledge gaps. Chapter 1 details the efforts made to uncover genomic loci underlying traits of nutritional importance (protein, zinc, calcium, and iron bioavailability) using genome-wide association study (GWAS). The GWAS panel was evaluated for two seasons (2012 and 2013) under field conditions in Michigan. The GWAS experiment identified several SNP markers, candidate genes, and superior germplasm that can be deployed for marker assisted breeding and selection. Phenotypic screening of the GWAS panel revealed large variability for mineral concentration (up-to 3-fold variation) and iron bioavailability (over 5-fold variation). Candidate genes and marker-trait associations for seed zinc, calcium, and iron bioavailability were discovered on chromosomes Pv07, Pv04, and Pv11 respectively. In chapter 2 a subset of 15 ADP genotypes selected for micronutrient composition, cooking time, and iron bioavailability were evaluated on farmers’ fields at nine locations across three agro-ecological zones in Uganda for two years (2015 and 2016). A GGE biplot analysis was used to investigate genotype by environment interactions for traits of interest. Seed yield was largely controlled by location (21.5 %) and the interaction between location and season (48.6 %). Cooking time was mostly controlled by genotype (40.6 %). Seed Fe concentration was largely controlled by genotype (27 %) and location (15 %). Seed Zn concentration was also mostly controlled by genotype and location effects at 23.1 and 25.5 % respectively. Chapter 3 describes a survey of farmers’ priority traits for biofortified beans and sensory analyses of five farmer selected genotypes using participatory variety selection. The most important bean variety attributes according to growers and consumers were early maturing, high yielding, fast cooking, and flavorful. Sensory panelists preferred flavorful beans with soft texture. The GWAS, G x E, and on-farm participatory variety selection and sensory evaluation research objectives generated novel germplasm for high seed Fe and Zn concentration, fast cooking, and candidate SNPs and genes that can be used to improve common bean for nutritional quality traits.
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