SEGREGATION OF MOLECULAR MARKERS SUPPORTS AN ALLOTETRAPLOID STRUCTURE FOR MEDICAGO-SATIVA X MEDICAGO-PAPILLOSA INTERSPECIFIC HYBRID

Cytogenetic analysis has indicated there is little genomic affinity between the genome of Medicago sativa L. and Medicago Papillosa Boiss. The objective of this study was to determine whether disomic segregation of alleles at isozyme and restriction fragment length polymorphism (RFLP) loci occurs in F1 hybrids of M. sativa x M. papillosa. We examined segregation of alleles at seven isozyme loci and 13 RFLP loci. Of the 20 loci analyzed, 11 exhibited a disomic pattern of inheritance, indicative of strict species-specific chromosome pairing in the M. sativa x M. papillosa hybrids. The other nine loci generally followed disomic inheritance, with exceptions. The results provide significant evidence in support of the concept that M. sativa x M. papillosa hybrids are basically allotetraploids with limited genomic affinity between the genomes. This report also represents the first documentation of the utility of RFLP markers in genetic analysis of alfalfa, a species with an essentially nonexistent genetic map.