Phylogenetic study on wild allies of Lima bean, Phaseolus lunatus (Fabaceae), and implications on its origin

An investigation was made of the phylogenetic relationships among wild acce ssions of Lima bean (Phaseolus lunatus) and wild allies of Mesoamerican and Andean origins, using electrophoresis of seed storage proteins and isozyme s. Mesoamerican wild species are phylogenetically more distant from P. luna tus than Andean species, and apparently belong to the tertiary gene pool of Lima bean. The Andean wild species, which are investigated for the first t ime, reveal a high similarity to the Lima bean, and particularly with its M esoamerican gene Fool. These Andean species probably constitute a secondary gene pool of Lima bean, and are thus of considerable interest in the conte xt of genetic improvement of the crop. Based on these observations, an Ande an origin is suggested for the Andean wild species and for P. lunatus. Thes e results point out the importance of collecting and conserving Andean Phas eolus germplasm.