FIG. 1.

Colonization of bean by wild-type strains X. fuscans subsp. fuscans (CFBP4834-R), X. campestris pv. campestris (ATCC 33913), and E. coli C600; by strains with mutations in hrp genes (33913HRCU and 33913HRPX); and by indigenous bacterial flora (IBF). Bacterial population densities were determined on bean leaves sampled at 3 h and 1, 4, and 11 days after spray inoculation (1 × 10⁶ CFU ml⁻¹). Means and SEMs were calculated for five leaves per sampling date. Mean population densities followed by different letters are significantly (P < 0.05) different on the basis of the Mann-Whitney test.