FIG. 4.

P. syringae pv. tomato DC3000 harpin mutants divide into three classes based on reduced abilities to elicit the HR in tobacco. Strains were infiltrated into panels of tobacco leaves at the indicated concentrations, which represent a ca. 1.5-fold dilution series. HR was scored and photographed ca. 24 h after infiltration. Boxed panels indicate the collapse of at least half of the infiltrated tissue and therefore a positive HR. Phenotypic classes: I, no detectable difference from the wild type; II, mild HR reduction; III, moderate HR reduction. This experiment was repeated six times with similar results.