FIG. 3.

hrpG and hrpX are essential for the expression of hpaR in the infected tissue. 8004pG28, 8004GpG28, and 8004XpG28 were inoculated into the cabbage (Brassaca oleracae cultivar Jingfeng no. 1) leaves by leaf clipping. Because the cells of the hrpG and hrpX mutants grow very poorly but the wild-type cells grow quite well inside the host plant (61, 62), to ensure that the cell numbers of 8004pG28, 8004GpG28, and 8004XpG28 were similar inside the inoculated leaves at the time of GUS staining, the cell concentrations of 8004pG28, 8004GpG28, and 8004XpG28 were adjusted to OD₆₀₀s of 0.1, 1.3, and 1.3, respectively. At 2 days postinoculation, the infected leaves were stained using an in situ GUS staining method to measure the β-glucuronidase activity, and the cell numbers inside the infected leaves were measured in a parallel experiment. Twenty leaves were inoculated (three leaves were chosen for GUS staining and five leaves for measurement of the cell number) in each experiment, and each experiment was repeated twice. The average bacterial numbers inside the tested leaves are indicated.