The PCR amplification and characterization of entire Pseudomonas syringae hrp/hrc clusters

SUMMARY We describe the use of degenerate primers to amplify the core hrp/hrc region of P. syringae pv. phaseolicola NPS3121. 18 826 bp were amplified using long-range PCR, digested and shotgun sequenced. Sequence analysis finds a hypervariable region between the hrpU and hrpC operons, and indications of positive selection on the hrpE locus. The primers were also shown to work on four other, widely divergent P. syringae strains. These primers should be of great utility for the characterization of hrp/hrc clusters from any P. syringae strain.