Genetic diversity and dissemination pathways of common bean in central Europe

Abstract

Common bean (Phaseolus vulgaris L.) was introduced in Europe from both Mesoamerican and Andean centers of origin and has been cultivated in central Europe for centuries. The first objective of this study was to evaluate genetic diversity and the population structure of 167 accessions divided into four groups according to geographical origin (Slovenia and Austria) and time periods (historical and present) using 14 simple sequence repeat (SSR) markers. The second objective was to improve our understanding of the pathways of dissemination and the evolution of this species in central Europe. Great allelic polymorphism was detected in all four groups of examined accessions, indicating that Slovene and Austrian bean germplasm in the past possessed significant variation that has been well preserved until today. In factorial correspondence analysis, accessions from different groups clustered together indicating potential gene flow between countries. The uncovered diversity corresponded very well to the two recognized gene pools (Andean and Mesoamerican). The majority of accessions in every single group belonged to the Andean gene pool. Strong predominance of Andean genotypes classifies Slovenia among other Mediterranean countries, like Spain and Italy. The latter appears as a most probable source of first beans in Slovenia and Austria. We assume that in the beginning of the previous century after very tight relationships between Slovenia and Austria loosened, introgression of genotypes from western and northern European countries took place in Austria, which resulted in a very high proportion of Mesoamerican genotypes that we found in the present Austrian germplasm (44%). Several putative hybrids between the Andean and Mesoamerican gene pools were detected in this study. Evolutionary significance, origin, and breeding potential of these recombinants are discussed here.