title: Characterization of transposon Tn5-facilitated donor strains and development of a chromosomal linkage map for Agrobacterium tumefaciens.
abstract: We have further characterized the transposon Tn5-facilitated chromosomal gene transfer system developed for Agrobacterium tumefaciens 15955. Using a strain whose chromosome contained Tn5, we compared the chromosome-mobilizing ability of plasmid pDP37 (containing Tn5) with that of its parent plasmid R68.45. For R68.45, we observed nonpolar transmission from multiple origins. For pDP37 we found polarized transmission from a single origin near ilv. When we examined the transmission gradients of a number of pDP37-containing donor strains each differing at the site of the chromosomal insertion we found just two classes. One set of donors transmitted markers with a gradient of Ilv+ greater than Rifr greater than His+ greater than Met+, whereas the second set transferred His+ greater than Rifr greater than Ilv+ greater than Met+. Using representatives from each transmission class of donor strains, we conducted matings to measure the degree of linkage between pairs of adjacent donor markers. From this information we developed a map of the A. tumefaciens 15955 chromosome. Attempts to isolate R-prime plasmids or Hfr-like donors were unsuccessful.
mesh_terms: D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial / Q000502:physiology*; D004251:DNA Transposable Elements; D004352:Drug Resistance, Microbial; D005798:Genes, Bacterial; D008040:Genetic Linkage; D007700:Kinetics; D010957:Plasmids; D012231:Rhizobium / Q000187:drug effects / Q000235:genetics*; D012293:Rifampin / Q000633:toxicity; D013045:Species Specificity
chemical_list: D004251:DNA Transposable Elements; D012293:Rifampin