PHAGE SENSITIVITY AND HOST-RANGE OF RHIZOBIUM STRAINS ISOLATED FROM ROOT-NODULES OF TEMPERATE LEGUMES

Twenty-five Rhizobium strains were isolated from root nodules of Astra galus spp. (10), Hedysarum alpinum (7), Glycyrrhiza pallidiflora (3) a nd Ononis arvensis (5). The sensitivity of these strains to bacterioph ages of Rhizobium loti, R. meliloti, R. galegae and R. leguminosarum w as studied. Phages specific to R. loti strains were shown to induce th e phage lysis of several Astragalus, Hedysarum and Ononis rhizobia. Te n R. loti strains tested for nodulation abilities on the plant hosts u nder investigation were able to develop nitrogen-fixing nodules on the Ononis arvensis roots. On the other hand, rhizobia from Ononis and Gl ycyrrhiza could form an effective symbiosis with Lotus corniculatus pl ants, so these bacteria are considered to belong to the Rhizobium loti taxon. Bacterial strains isolated from Astragalus and Hedysarum were observed to cross-nodulate their plant hosts as well as Oxytropis camp estris. Glycyrrhiza uralensis and Ononis arvensis plants, whereas they could not nodulate Lotus plants. It is concluded that these Rhizobium strains comprise a cross-inoculation group related to Rhizobium loti.