CHARACTERIZATION OF RHIZOBIA HOMOLOGS OF SINORHIZOBIUM-MELILOTI INSERTION SEQUENCES ISRM3 AND ISRM4

Homologues to Sinorhizobium meliloti insertion sequences ISRm3 and ISR m4 were found within Rhizobium leguminosarum by. viciae field populati ons. Similarly, homologous sequences to S. meliloti ISRm4 were found i n S. fredii strains. Based on the polymerase chain reaction, we cloned and partially sequenced some of these putative insertion sequence ele ments. DNA sequence comparisons indicate that S. meliloti and R. legum inosarum ISRm3-type elements are closely related whereas the ISRm4 hom ologues show distinct relationships. In addition, specific primers for PCR recognition of ISRm3 and ISRm4 elements in rhizobia species and S . meliloti ISRm6 were designed. (C) 1998 Federation of European Microb iological Societies. Published by Elsevier Science B.V.