GENETIC DIVERSITY OF RHIZOBIAL SYMBIONTS ISOLATED FROM LEGUME SPECIESWITHIN THE GENERA ASTRAGALUS, OXYTROPIS, AND ONOBRYCHIS

The genetic diversity of 44 rhizobial isolates from Astragalus, Oxytro pis, and Onobrychis spp. originating from different geographic locatio ns was evaluated by mapped restriction site polymorphism (MRSP) analys is of 16S rRNA genes and by PCR DNA fingerprinting with repetitive seq uences (REP-PCR). A comparison of tree topologies of reference strains constructed with data obtained by MRSP and by 16S rRNA gene sequence analyses showed that the topologies were in good agreement, indicating that the MSRP approach results in reasonable estimates of rhizobial p hylogeny. The isolates were distributed into 14 distinct 16S rRNA gene types clustering into three major groups which corresponded with thre e of the genera within the legume symbionts. Most of the isolates were within the genus Mesorhizobium. Five were identified with different g enomic species nodulating Lotus spp. and Cicer arietinum. Three Astrag alus isolates were classified as Bradyrhizobium, one being similar to Bradyrhizobium elkanii and another being similar to Bradyrhizobium jap onicum. Six of the isolates were related to species within the genus R hizobium. Two were similar to Rhizobium leguminosarum, and the remaind er were identified as Rhizobium gallicum. DNA fingerprinting by REP-PC R revealed a high level of diversity within single 16S ribosomal DNA t ypes. The 44 isolates mere distributed into 34 REP groups. Rhizobial c lassification at the genus and probably also the species levels was in dependent of geographic origin and host plant affinity.