ISOLATION AND CHARACTERIZATION OF A PSYM LOCUS OF RHIZOBIUM SP BR816 THAT EXTENDS NODULATION ABILITY OF NARROW HOST-RANGE PHASEOLUS-VULGARIS SYMBIONTS TO LEUCAENA-LEUCOCEPHALA

Introduction of a cosmid library of megaplasmid DNA of Rhizobium sp. B R816, a broad host range Rhizobium strain, into R, etli CE3, a narrow host range bean symbiont, resulted in the isolation of a transconjugan t that could effectively nodulate Leucaena leucocephala, Analysis of t he corresponding cosmid, pBRF2, revealed the presence of genes require d for eliciting nitrogen-fixing nodules on L. leucocephala. Subcloning and Tn5 tagging identified a locus responsible for the host range ext ension, Sequence analysis of this locus revealed an ORF that shows sig nificant identity with NodO of R, leguminosarum by. vicine.