Figure 10.
BABA Action Is Defective in ios1 Mutants.
(A) BABA-induced resistance. Bacterial titers in 5-week-old Ler-0, ios1-1, Col-0, and ios1-2 were determined at 2 dpi with 106 cfu/mL Pst DC3000 or 5 × 105 cfu/mL Psm ES4326. Two days before bacterial inoculation, plants were soil-drenched with water as a control or 225 µM BABA. Values are means ± se of three independent experiments each with three plants (n = 9). Asterisks indicate a significant difference to respective water-treated control based on a paired two-tailed t test (P < 0.01).
(B) BABA priming of PTI-mediated callose deposition. Leaves of water- or BABA-pretreated (225 µM) Ler-0 and ios1-1 or Col-0 and ios1-2 were syringe-infiltrated with 1 µM flg22 and samples were collected 6 h later for aniline blue staining. Values are average ± sd from three independent experiments each consisting of nine plants (n = 27). Asterisks indicate a significant difference to water-treated respective controls based on a paired two-tailed t test (P < 0.01).
(C) BABA priming of PTI-mediated FRK1 expression. Ten-day-old Ler-0 and ios1-1 or Col-0 and ios1-2 seedlings grown on 0.5× MS medium supplemented with 30 µM BABA (BABA) or not (Water) were submerged with water (Mock) or 1 µM flg22, and FRK1 expression levels were analyzed 60 min later by RT-qPCR. UBQ10 was used for normalization. Relative gene expression levels were compared with respective water + mock-treated wild type (defined value of 1). Values are means ± sd of two independent experiments each with three plants (n = 6). Asterisks indicate a significant difference to water-treated respective controls based on a paired two-tailed t test (P < 0.01).
(D) BABA inhibition of bacteria-mediated stomatal reopening. Stomatal apertures in epidermal peels from water- (W) or BABA-treated (225 µM) (B) Ler-0 and ios1-1 or Col-0 and ios1-2 were analyzed after 1.5 and 6 h exposure to MgSO4 (Mock) or 108 Pst DC3000. Results are shown as mean ± 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).