|Van Berkum, Peter|
Submitted to: Nitrogen Fixation International Congress
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/1997
Publication Date: N/A
Technical Abstract: We have improved PCR-RFLP analysis of rhizobial 16S rDNA by constructing a database of mapped restriction sites in this gene of bacteria in the family Rhizobiaceae. The method was applied to the analysis of 44 rhizobial isolates from Astragalus, Oxytropis and Onobrychis spp. which originated from different geographic locations. The isolates were distributed into 14 16S rDNA types and were clustered into three major groups corresponding to three genera. Most of the isolates were classified within the genus of which R. loti is the type species. Five of these types were associated with different genomic species nodulating Lotus spp. and Cicer arietinum. Three Astragalus strains were classified as Bradyrhizobium, one similar to B. elkanii and the other to B. japonicum. Six isolates were classified within the genus Rhizobium. PCR DNA fingerprinting (rep-PCR) revealed a high level of diversity within single 16S rDNA types. Rhizobial classification was independent of geographic origin and host plant affinity.