Figure 1.
A Critical Role for IOS1 in Arabidopsis Resistance to Hemibiotrophic Bacteria.
(A) Disease symptoms in ios1 mutants. Five-week-old Arabidopsis were dip-inoculated in a bacterial solution of 106 cfu/mL Pst DC3000 or 5 × 105 cfu/mL Psm ES4326. Symptoms were evaluated at 3 dpi. These experiments were repeated at least twice with similar results.
(B) Bacterial growth in ios1 mutants. Five-week-old Arabidopsis were dip-inoculated as in (A) and bacterial titers were evaluated at 2 dpi. Values are means ± se of two independent experiments each consisting of three plants (n = 6). Asterisks indicate a significant difference to the respective wild-type control based on a paired two-tailed t test (P < 0.01).
(C) Growth of Pst DC3000 in lines overexpressing IOS1. Bacterial titers in 5-week-old Col-0 and IOS1 overexpression lines OE1 and OE3 were determined at 3 dpi with 106 cfu/mL Pst DC3000. Values are means ± se of three independent biological replicates each with three plants (n = 9). Asterisks indicate a significant difference to Col-0 wild-type based on a paired two-tailed t test (*P < 0.01).
(D) Stomatal innate immunity in lines overexpressing IOS1. Stomatal apertures in leaf epidermal peels from 5-week-old Col-0 and IOS1 overexpression lines OE1 and OE3 were analyzed after 1.5 or 3 h exposure to MgSO4 (Mock) or 108 cfu/mL Pst DC3000. Values are shown as means ± se of three independent experiments each consisting of at least 60 stomata (n > 180). Asterisks indicate a significant difference to respective mock controls based on a paired two-tailed t test analysis (P < 0.001).