Genetic diversity of a natural population of Rhizobium leguminosarum biovar trifolii analysed from field nodules and by a plant infection technique

We compared trapping of Rhizobium leguminosarum biovar trifolii isolates under field soil and non-soil environmental conditions. Isolates were obtained from white clover (Trifolium repens L.) and red clover (T. pratense L.) grown directly in the field and from plants inoculated with soil from the same site using a plant infection technique. Isolates were identified by genomic polymerase chain reaction (PCR) fingerprinting using primers derived from the enterobacterial repetitive intergenic consensus (ERIC) sequences. The isolates trapped from soil dilutions in the laboratory included a number of major ERIC types that were not found in the field trapped nodules, suggesting that sampling of clover Rhizobium strains from soil dilutions may not be representative of the field nodulating population.