Similarities Between Highly Transmissable Plasmids of Rhizobium and Agrobacterium

Abstract

Most of the fast-growing Rhizobium strains produce a similar small molecular weight bacteriocin (Hirsch, 1979). R. leguminosarum strain 248, containing the highly self-transmissable plasmid pRL1JI, Is non-small bacteriocin producing strain and is sensitive to small bacteriocin. By introducing pRL1JI in a small bacteriocin producing strain the production of small bacteriocin is stopped by a function located on this plasmid that represses small bacteriocin synthesis (Brewin et al., 1980). We investigated 50 independent field isolates of R. leguminosarum, two R. trifolium strains, and two R. phaseoli strains on their ability to produce small bacteriocin and on the presence of a self-transmissable plasmid. Most of these strains produced small bacteriocin. Four strains did not and only in these four strains the presence of a self-transmissable plasmid could be demonstrated. The strains were R. leguminosarum RBL4 and RBL16, R. trifolii RCR5 and R. phaseoli RBL822. The presence of a self-transmissable plasmid in the strains was confirmed by gelelectrophoresis of transconjugant strains.