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 accessions of Lima bean (Phaseolus lunatus) and wild allies of Mesoamerican and Andean origins, using electrophoresis of seed storage proteins and isozymes. Mesoamerican wild species are phylogenetically more distant fromP. lunatus than Andean species, and apparently belong to the tertiary gene pool of Lima bean. The Andean wild species, which are investigated for the first time, reveal a high similarity to the Lima bean, and particularly with its Mesoamerican gene pool. These Andean species probably constitute a secondary gene pool of Lima bean, and are thus of considerable interest in the context of genetic improvement of the crop. Based on these observations, an Andean origin is suggested for the Andean wild species and forP. lunatus. These results point out the importance of collecting and conserving AndeanPhaseolus germplasm.