EXTENT OF RFLP VARIABILITY IN TETRAPLOID POPULATIONS OF ALFALFA, MEDICAGO-SATIVA

Seven widely-cultivated alfalfa varieties and three ecotypes adapted t o Central Italy were used to evaluate the extent of polymorphism in th at species. Twenty plants per accession were analysed with 16 RFLP pro bes combined with three restriction enzymes (48 probe/enzyme combinati on in total) and the data were used to compute the Nei's similarity in dex taken as a measure of inter- and intra-population RFLP variability . The varieties were, in general, more homogeneous than the ecotypes a nd the cultivars 'Adriana and 'Florida' could be differentiated more e asily than the others. Few accession-specific hybridizing fragments we re scored and seven populations could be distinguished from the others on the basis of significant differences in the frequencies of specifi c fragments. The DNA of plant populations of several sizes was bulked and the ability to detect a given fragment in pooled samples was relat ed to the fraction of plants having that fragment among the plants for ming the bulk. The results are discussed with special emphasis on the practical utilization of RFLPs for varietal identification.