GENETIC-STRUCTURE OF WILD BEAN POPULATIONS IN THEIR SOUTH-ANDEAN CENTER OF ORIGIN

The genetic structure of wild common bean populations was studied in t he South-Andean centre of origin of the species. Plants were collected from 21 populations in Argentina and genetic variability was assessed for molecular and resistance markers. Polymorphism was weak for phase olin, the major seed-storage protein, and for RAPD markers, while a hi gh level of polymorphism was observed for resistance to anthracnose, o ne of the most important diseases of common bean. For the three traits , within-population variability was important and represented between 43.6% and 67.5% of the total variation. Although among-population diff erentiation was significant for all the traits, no correlation was fou nd between the population distances calculated from RAPDs and resistan ce. These results indicate that pathogen selection pressure may be an important factor influencing the distribution of variability within an d among host plant populations.