Genetic Diversity in a Core Collection Established from the Main Bean Genebank in Spain

Common bean (Phaseolus vulgaris L.) is a traditional crop in many Spanish regions. A major collection of Spanish common bean landraces is maintained at the National Genebank in the Center for Plant Genetic Resources (CRF), Alcala de Henares, Madrid, Spain. A core collection including 200 common bean accessions was established from the CRF collection. We sought to analyze the genetic diversity of this CRF core collection using morpho-agronomic traits, phaseolin seed protein, and a set of 11 molecular markers. Accessions were classified in 65 groups according to their seed phenotype. Seventy-one accessions have appropriate qualities for culinary use as green or snap beans. The four bean growth habits were present among the accessions included in the CRF core collection, with the indeterminate climbing habit (Type IV; 113 accessions) being the most common. Five different phaseolin patterns were found, the most common being type C (86 accessions), followed by types T (59 accessions) and S (42 accessions). With the set of molecular markers used, an average number of 6.18 alleles marker(-1) and an average polymorphism information content marker(-1) of 0.66 were found. The dendrogram and the principal components analysis developed using the molecular marker data revealed the existence of two main groups of accessions corresponding to the Middle American and the Andean gene pools, respectively, and suggested the existence of some intermediate forms. The possible origin of these putative intermediate forms is discussed. Knowledge of the genetic diversity in the CRF core collection will contribute to improved use and conservation of Spanish bean genetic resources.