Figure 6.

Pre‐inoculation with Xanthomonas citri ssp. citri (X. citri) strain A^T protects Citrus limon from canker disease. (a) Phenotypic response of lemon leaves pre‐inoculated with X. citri A^T tagged with green fluorescent protein (GFP) or mock‐inoculated by cotton swab. At 48 h post‐inoculation, the leaves were subsequently challenged, via spraying, with the pathogenic X. citri T‐GFP strain. Sections from the left panels are shown magnified in the right panels. Leaves were photographed under white and UV light. Scale bar, 10 mm. (b) Number of canker lesions per square centimetre in pre‐inoculated leaves at 20 days post‐inoculation (dpi). Values are expressed as means ± standard deviation (SD) from three independent biological replicates, each involving three different plants and five different leaves per plant. The dataset marked with an asterisk is significantly different as assessed by Student's t‐test (P < 0.05). (c) Canker symptoms, developed at 20 dpi, of lemon leaves co‐inoculated with equal amounts of both bacterial strains by cotton swab. Scale bar, 10 mm.