REPEATED SEQUENCE RS-ALPHA IS DIAGNOSTIC FOR BRADYRHIZOBIUM-JAPONICUMAND BRADYRHIZOBIUM-ELKANII

The genome of Bradyrhizobium japonicum and B. elkanii contains multipl e copies of the repeated DNA sequence RS alpha. A collection of 18 B. japonicum, 4 B. elkanii and 72 other bacterial strains was screened by polymerase chain reaction (PCR) using a pair of primers specific for RS alpha. Only strains of B. japonicum and B. elkanii gave the predict ed amplification product. Restriction analysis of PCR products obtaine d from different strains of B. japonicum showed that the RS alpha sequ ence was generally conserved, The usefulness of RS alpha as a specific probe for Bradyrhizobium strains capable of nodulating soybean was al so demonstrated.