A Filamentous Hemagglutinin-Like Protein of Xanthomonas axonopodis pv. citri, the Phytopathogen Responsible for Citrus Canker, Is Involved in Bacterial Virulence
Figure 2
Expression of XacFhaB and effects of XacFhaB and XacFhaC mutations on pathogenicity.
(A) RT-PCR of XacFhaB with RNA obtained from X. axonopodis pv. citri cultivated in SB or XVM2 medium (left gels) or recovered from inoculated orange at 0 or 4 days post-infection (right gels). As constitutive controls a fragment of 16S rRNA was amplified using the same RT-PCR conditions (bottom gels). (B) X. axonopodis pv. citri wild-type (XacWT) and knocked out strains ΔXacFhaB and ΔXacFhaC, were inoculated at 105 cfu/ml (left leaf) or 104 cfu/ml (right leaf) into the intercellular spaces of fully expanded orange leaves. A representative leaf is shown 7 days after inoculation. Dashed lines indicate the infiltrated area. (C) Bacterial growth of XacWT, ΔXacFhaB and ΔXacFhaC in orange leaves inoculated as described in A at 105 cfu/ml, values represent means of three samples and are representative of three independent experiments. Error bars are standard deviations. (D) Quantification of canker number in orange leaves after one month of spray inoculation with XacWT, ΔXacFhaB and ΔXacFhaC strains at 109 cfu/ml. Bars are the means of 20 leaves assayed and error bars are standard deviations, the results are representative of three independent experiments. (E) Epiphytic populations of XacWT, ΔXacFhaB and ΔXacFhaC strains on orange leaves. Each data point is the mean of four leaves assayed and error bars are standard deviations, the results are representative of five independent experiments.
doi: https://doi.org/10.1371/journal.pone.0004358.g002