Case studies on breeding systems and its consequences for germplasm conservation: 3. Electrophoretic mobility of phaseolins in wild populations of Lima beans (Phaseolus lunatus L.) in the Central Valley of Costa Rica

We studied the variation in the electrophoretic mobility of phaseolins of 2 02 individual seeds from thirty-eight wild populations of Lima beans ( Phas eolus lunatus) in the Central Valley of Costa Rica. We found four main poly peptides or banding regions with molecular weights which ranged from 21.5 t o 31 kDaltons. Two of these peptides were polymorphic, and their combinatio n resulted in four distinct genotypes. The frequency of the different genot ypes varies among populations, but two of them, namely (BC11)-C-11, (BC22)- C-22, were found in most of the populations studied (37 out of 38 populatio ns examined). Overall, there was a lack of heterozygotes among the individu als examined, which strongly suggests that there is gametic disequilibrium for the encoding regions involved in the synthesis of these polypeptides. W hen we arranged the populations into eight groups according to their proxim ity and phenology, we found that the distribution of the peptides was also variable among them. The possible association between the distribution of t he patterns of electrophoretic mobility observed and climatic factors, such as mean annual rainfall, mean annual temperature and mean annual relative humidity is discussed.