A plasmid sequence from Rhizobium leguminosarum 300 contains homology to sequences near the octopine TL-DNA right border

Abstract

The DNA sequence from a Rhizobium leguminosarum 300 (RL300) plasmid that contains homology to the Tc-DNA of Agrobacterium tumefaciens is described. The RL300 sequence has 78% homology to a 359 bp sequence in the Tc-DNA of pTi15955. The RL300 homology starts approximately 100 bp from the 24 bp border sequence of the TL-DNA and ends approximately 3 bp from an IS66 homolog in the Tc-DNA. An unusual feature of the RL300 homology is the presence of 81 bp direct repeats with Tc-DNA homology, separated by 201 bp. One end of each direct repeat has a 12 bp palindrome. Four cloned sequences of RL300 with homology to the T DNA region were hybridized to plasmid lysates of RL300 derivatives to determine the source of each plasmid. The sequenced homolog, originally on pRH228, was isolated from pRL7JI; the other 3 homologs were isolated from the transmissable plasmids pRL7JI (pRH235) and pRL8JI (pRH235 and pRH236).