Figure 7. Number of colony-forming units (CFU) of Xac strains per cm² of leaf tissue during the first twelve days after inoculation.

The abaxial surface of young leaves was pricked by using insect pins whose tips were previously immersed in the bacterial suspension for Xac hrcU mutant strains (A) or by infiltration into leaves with needleless syringes for Xac hrpB2 mutant strains (B). Discs of infected leaves were excised, homogenized and cultured quantitatively by incubation on agar plates. The assays were performed in triplicate and error bars represent the standard deviation of the data. Differences in the initial bacterial populations are due to differences in the inoculation protocols. (A) Xac wild-type (diamonds), ΔhrcU (squares), ΔhrcU+pUFR047_hrcU (triangles), ΔhrcU+pUFR047_hrcU_AAAH (crosses). (B) Xac wild-type (diamonds), ΔhrpB2 (squares), ΔhrpB2+pUFR047_hrpB2 (triangles).