Fig. 7.

Callose deposition induced by different strains of Xcc. (A) N. benthamiana leaves were infiltrated with a 1×10⁶ cfu ml^–1 suspension of different Xcc strains; Xcc8004 (wild type), gumD (xanthan-deficient mutant), ΔrpfF (DSF-deficient rpfF deletion mutant), and the ΔrpfF-gumD double mutant. Callose deposition was visualized by staining with aniline blue and examined using a stereo fluorescence microscope 24h post-inoculation. White dots in these pictures are indicative of callose deposition. Scale bars=500 μm. (B) Average number of callose deposits per 0.5mm² area. Error bars represent SD values from three leaves of each plant and three independent experiments. Six microscopic fields from each leaf were analysed. * indicates (P<0.001) significantly different callose deposits induced by the Xcc gumD mutant compared with either the wild-type Xcc8004 strain or the ΔrpfF-gumD double mutant as determined by two-tailed Student’s t-test.