Molecular analysis of genetic variation among alfalfa (Medicago sativa L.) and Medicago ruthenica clones

Medicago ruthenica (L.) Ledebour is an allogamous diproid (2n = 2x = 16) perennial indigenous to Siberia, Mongolia and Manchuria with a remarkable ability to survive mechanical and physiological stress. The possibility of hybridizing alfalfa (Medicago sativa L.) and M. ruthenica is being investigated. The objective of the current research was to conduct a molecular assessment of genetic relatedness and inter- and intra-specific genetic variation in cultivated alfalfa (2n = 4x = 32) and M. ruthenica. Seventeen alfalfa clones, selected randomly from the broad-based population W10- AC3, and 17 agronomically superior M. ruthenica clones, tracing to 17 collection sites in Inner Mongolia, were studied using Random Amplified Polymorphic DNA (RAPD), Anchored Microsatellite Priming (AMSP), and Simple Sequence Repeat (SSR) analyses of genomic DNA. Mean genetic distances (GD) within M. ruthenica and alfalfa clones were 0.5 and 0.56, respectively, based on RAPD/AMSP data, and 0.29 and 0.40, respectively, based on SSR data. Alfalfa and M. ruthenica were genetically distant (RAPD/AMSP GD = 0.73); however, this difference does not necessarily preclude the possibility of interspecific hybridization, although the use of techniques such as bridge crossing, embryo culture rescue and/or protoplast fusion may be necessary.