Genetic Diversity of the Guatemalan Climbing Bean Collection

Common bean (Phaseolus vulgaris L.) is the most important legume crop for human consumption in the world and is the primary source of protein in the daily diet in Central America. In Guatemala, it occupies 184,000 hectares or 17.8% of available production acreage where 8 of 10 native children suffer from chronic malnutrition, the highest level in Latin America. For this reason, food security plays a key role in the development of a healthy country. At this point, bean breeders are challenged to increase seed yield and maintain seed quality while breeding for resistance to several diseases whose incidence has increased due to climate change. Race Guatemala of common bean includes climbing beans from the highlands of Guatemala where poverty is the highest, and it is a resource of new alleles for bean improvement. The objectives of this research are to evaluate and describe the population structure, genetic diversity, and genetic differentiation of a Guatemalan climbing bean collection of 377 landraces using SNP markers, and to perform a genome-wide association study (GWAS) to map important agronomic traits such as disease resistance. The population structure was characterized using fastSTRUCTURE and performing a maximum likelihood tree and principal components analyses. In the GWAS study, the peak SNP in rust (Uromyces appendiculatus) resistance was found inside a gene that codifies for a leucine-rich repeat transmembrane protein kinase at the beginning of chromosome 2. In general, the results are promising for the use of this collection as a source of alleles in common bean breeding.