Comparison of two Xanthomonas campestris pathovar campestris genomes revealed differences in their gene composition.

For the Xanthomonas campestris pathovar campestris wild-type strain B100 a plasmid-based clone library was constructed. The plasmids carried chromosomal fragments of 3-4 kb in size that were tagged in vitro with the artificial transposon KAN-2. More than 3000 of the transposon target sites were characterized by DNA sequencing. The sequences obtained were compared to the recently published genome of Xanthomonas campestris pathovar campestris strain ATCC 33913. Most of the sequenced clones derived from strain B100 matched the chromosomal sequence of strain ATCC 33913. An alignment to the circular map of this chromosome revealed that the similarities were statistically distributed over the entire genome of strain ATCC 33913. The similarity was obvious for protein coding sequences, as well as for mobile genetic elements. However, four regions in the genome of Xanthomonas campestris pathovar campestris strain ATCC 33913, ranging in size from 11 to 37 kb, were not represented in the sequenced clone library of Xanthomonas campestris pathovar campestris strain B100. On the other hand, 1.2% of the sequenced clones originating from Xanthomonas campestris pathovar campestris strain B100 showed no or insignificant similarities to the genome of strain ATCC 33913.