CHARACTERIZATION OF RHIZOBIUM-HEDYSARI BY RFLP ANALYSIS OF PCR AMPLIFIED RDNA AND BY GENOMIC PCR FINGERPRINTING

The taxonomic and discriminatory power of RFLP analysis of PCR amplifi ed parts of rhizobial rrn operons was compared to those of genomic PCR fingerprinting with arbitrary and repetitive primers. For this purpos e, the two methods were applied for characterization of a group of bac terial isolates referred to as Rhizobium 'hedysari'. As outgroups, rep resentatives of the family Rhizobiaceae, belonging to the Rhizobium ga legae, Rhizobium meliloti, Rhizobium leguminosarum and Agrobacterium t umefaciens species were used. By the RFLP analysis of the PCR products corresponding to the variable 5'-half of the 23S rRNA gene and of the amplified spacer region between the 16S and 23S rRNA genes all Rh. 'h edysari' strains studied were tightly clustered together while the out groups were placed in an outer position. The PCR products of the 3' en d parts of the 23S rDNA did not show significant RFL polymorphism and no species differentiation on their basis was possible. In parallel, a nalysis of the same strains was performed by PCR amplification of thei r total DNA with 19, 18 and 10 bp long arbitrary primers (AP-PCR) as w ell as with single primers corresponding to several bacterial repetiti ve sequences (rep-PCR). By both AP and rep-PCR an identification of ev ery particular strain was achieved. In general, all primers provided t axonomic results that are in agreement with the species and group assi gnments based on the RFLP analysis of the mt operons. On the basis of the results presented here it can be concluded that AP and rep-PCR are more informative and discriminative than rDNA and RFLP analysis of th e rhizobial strains studied.