Figure 3.

Hpa1 enhances Xanthomonas axonopodis pv. citri (Xac) virulence in citrus leaves. (A) Xac wild‐type, XacΔhpa1 and XacΔhpa1c strains were inoculated at 10⁷ colony‐forming units (CFU)/mL, diluted in 10 mm MgCl₂, into the intercellular spaces of fully expanded citrus leaves. The representative photograph was taken at 7 days post‐inoculation. (B) Bacterial growth of Xac, XacΔhpa1 and XacΔhpa1c in citrus leaves inoculated as described in (A). Values represent the means of three independent experiments. Error bars are standard deviations. (C) Serial dilutions of Xac and XacΔhpa1 were inoculated at the concentrations stated in citrus leaves. (D) Quantification of canker number in citrus leaves inoculated as described in (C). Bars are the means of 10 leaves assayed and error bars are standard deviations. The results are representative of three independent experiments. (E) Co‐infiltrations with Hpa1 enhance bacterial virulence. Xac wild‐type was co‐infiltrated with 5 μm Hpa1 in the right halves of citrus leaves at the bacterial concentrations indicated. (F) Quantification of canker number in leaves inoculated as described in (E).