FIG. 4.

Competitive index virulence analysis of the ΔhopW1-1 or ΔhopW1-2 single mutant, the ΔhopW1-1 ΔhopW1-2 double mutant, or the ΔhopW1-1 ΔhopW1-2 double mutant carrying a plasmid expressing the hopW1-1/2 ORF from a P_lac promoter in mixed infections with Pph1448a. Eight-day-old bean plants were inoculated with 200 μl of a 5 × 10⁴-CFU/ml mixed bacterial suspension, containing equal numbers of CFU of wild-type and mutant bacteria, and leaves were sampled at 4, 7, and 14 days postinoculation (dpi). For virulence assays, the CI is defined as the mutant-to-wt output ratio divided by the mutant-to-wt input ratio. CI values correspond to the means for three samples. A dashed line, corresponding to a CI of 0.5, is included for reference. Error bars represent the standard errors. Asterisks indicate results significantly different from 1 as established by Student's t test (P < 0.05). Mean values marked with the same letter (a, b, or c) indicate results not significantly different from each other, as established by Student's t test (P < 0.05). Mean values marked with 1 indicate results significantly different from the CI for Pph1448a carrying the empty vector (pAMEX), as established by Student's t test (P < 0.05). Mean values marked with 2 indicate a result not significantly different from the CI for Pph1448a carrying the empty vector (pAMEX), as established by a Mann-Whitney test (P < 0.05). A different test was used for this value in accordance with the specific recommendation provided by the statistics software program used.