Figure 1.

Effect of thiamine application on disease progression in Arabidopsis. A, Arabidopsis ecotype Col-0 plants were inoculated with virulent P. syringae pv tomato strain DC3000 (1 × 10⁸ CFU mL⁻¹ in 250 μg mL⁻¹ Tween 20 [mock]) at 4 h after spraying mock or thiamine (10 mm in mock) solutions. Col-0 was also inoculated with DC3000 expressing avrRpm1 [DC3000 (avrRpm1)] as a resistance control. Samples were collected from 25 plants at 4 dpi. The necrotic lesion on Arabidopsis ecotype Col-0 caused by DC3000 was suppressed in thiamine-treated plants. B, DC3000 growth in the leaves of Arabidopsis ecotype Col-0 treated with increasing concentrations of thiamine prior to DC3000 inoculation. Samples (±1 g fresh weight) were collected from five plants 3 dpi. Each bar represents the mean ± se. Different letters indicate statistically significant differences between treatments (Duncan's multiple range test; P < 0.05). C, Inhibitory effects of thiamine on bacterial growth in Arabidopsis. Arabidopsis ecotype Col-0 was inoculated with DC3000 1 and 5 d after 10 mm thiamine treatment. Samples (±1 g fresh weight) were collected from five plants at 6, 12, 24, and 48 h after inoculation. Each point represents the mean ± se of bacterial count. dpt, Days posttreatment.