TABLE 3.

Frequency of single-crossover recombinants is dependent upon the orientation of Placa

ConstructOrientation relative to PlacNo. of recombinants
S. melilotiS. medicae
pBP91Same direction1.8 × 10−41.7 × 10−4
pBP92Opposite direction<10−8<10−8
  • a Plasmid pBP91 or pBP92 were conjugated from E. coli into either S. meliloti or S. medicae and recombinants were selected on the basis of antibiotic resistance. Data presented are the mean of one experiment with three independent replicates where the standard deviation is less than 10%. The experiment was also replicated on three separate occasions with comparable data.