Genome Wide Association Studies and Genetic Diversity in Andean, Mesoamerican and Combined Genepool Collections of Dry Beans (Phaseolus vulgaris L.) for Control of Biotic and Abiotic Stresses
Abstract
Dry beans of the species common bean (Phaseolus vulgaris), one of the world’s most important grain legumes for human diets, are produced on marginal lands in many geographic regions where biotic and abiotic stressors constrain yield potential. Among the biotic stresses, diseases like common bacterial blight (CBB) and charcoal rot (CR) are major problems associated with climate change, which creates conducive conditions for the survival of pathogens. Aluminum (Al) toxicity is among the important abiotic stresses limiting common bean production in the world. The production of common beans is constrained by Aluminum toxicity in areas where acidic soils with pH below 4.3 are prevalent. The goals of this study were to assess and quantify the phenotypic and genetic variation for resistance to the two diseases and tolerance to one of the abiotic stresses (Al toxicity in three panels of Andean, Mesoamerican, and combined dry bean gene pools, identify genotypes that could serve as parents, detect genotype x phenotype associations and identify candidate genes through a field and greenhouse evaluation using randomized designs. Different statistical methods including analysis of variance, multivariate analysis (principal component analysis and hierarchical clustering), and genome-wide association studies were used for associating phenotypic and genotypic information for the panels. The study indicated the presence of high genetic and trait level diversity as well as high amounts of linkage disequilibrium in the panels. Genetic distance was proportional to the genetic variation. The Mesoamerican panel showed the presence of dual resistance for CBB and CR. The Andean panel showed sources of tolerance to Al toxicity in a rapid hydroponic screening assay. GWAS detected significant markers - trait associations (MTAs) for traits measured. Candidate resistance genes to CBB and aluminum toxicity were proposed to explain the MTAs in the two panels. Utilization of a combined panel based on a freely available reference collection with a well-characterized population structure was suggested for validation of the genes and trait associations we discovered in the individual gene pools across the species as a whole.
Subject Area
Biology|Genetics
Recommended Citation
Daniel Ambachew Demissie,
"Genome Wide Association Studies and Genetic Diversity in Andean, Mesoamerican and Combined Genepool Collections of Dry Beans (Phaseolus vulgaris L.) for Control of Biotic and Abiotic Stresses"
(2020).
ETD Collection for Tennessee State University.
Paper AAI28153193.
https://digitalscholarship.tnstate.edu/dissertations/AAI28153193