Use of Molecular Markers in Alfalfa for Construction of a Genetic Map and Studying Genetic Rearrangements in Non-Sexually Derived Hybrids

Two genomic libraries have been constructed from Medicago saliva DNA reslfictcd with both Pstl and EcoRT. The libraries have been screened and compared for the presence of highly repeated DNA sequences. Restriction fragment length polymorphism among 3 varieties of M. saliva (Rangelander, Adriana, CADL) and 3 species of the genus Medicago (M. coerulea, M. falcata, M. arborea) has been investigated using a large number of probe-enzyme combinations .. Four-and 6-base cutter restriction enzymes have been used. DNA electrophoresis has been performed with· 2 substrates (agarose and polyacrylamide) in order to detect polymorphism at a higher range of fragment lengths. About 80% of the probes analysed gave polymorphism for at least one pair of accessions. The nature of polymorphism is due to insertion-deletion mutations. Intrapopulation polymorphism was very poor for CADL and higher for the other populations. Genotypes of 3 diploid accessions were intercrossed in order to construct the segregating population to be used for mapping. Polymorphic probe-enzyme combinations were used for the analysis of the somatic hybrids obtained from the protoplasl electrofusion of M. saliva x M. coerulea.