Tn 5 -Induced Mutations in the Enterobacterial Phytopathogen Erwinia chrysanthemi

Abstract

Escherichia coli (2492/pJB4JI) matings with Erwinia chrysanthemi produced kanamycin resistant (Km r ) transconjugants, a majority of which were gentamicin sensitive (Gm s ). A small proportion (about 0.8%) of the Km r Gm s clones were either auxotrophic or failed to catabolize galacturonate (Gtu − ). The R plasmid (pJB4JI) DNA was detected in the parent E. coli strain and in a Km r Gm r transconjugant, but not in Km r Gm s E. chrysanthemi strains carrying Tn 5 -induced mutations. In Hfr crosses, Km r (Tn 5 ) was found linked with most mutations. A majority (>95%) of prototrophic recombinants were Km s , except for Leu + and Arg + recombinants which were 30 to 50% Km s . Spontaneous revertants were obtained for all markers except car, gtu, lys, thr , and trp. Prototrophic revertants, with the exception of Met + , Leu + , or His + clones, were Km s . We conclude from both genetic and physical data that Tn 5 transposed from pJB4JI into different sites on the chromosome of E. chrysanthemi.