Fig 5. H₂O₂ in PPA-pretreated leaves infected with bacteria.

Twenty-day-old leaves pretreated with 0.3% acetone (Mock, the solvent for BTH), 100 μM BTH for 3 days, or 40 μM PPA for 2 days, then infiltrated with P. syringae (DG3, OD₆₀₀ = 0.005) for the indicated times. The infiltrated leaves were collected and incubated in CeCl₃ as described in the Methods. A, Cell morphology of mock-treated leaves at 36 h post bacterial inoculation. Note the cerium-free bacteria. B–D, TEM images of BTH-treated leaves after DG3 inoculation for 12 h (B), 24 h (C), 36 h (D). E–G, TEM images of PPA-treated leaves after DG3 inoculation for 12 h (E), 24 h (F), 36 h (G). Arrowheads indicate cerium deposits. Ch, chloroplast; CW, Cell wall; M, Mitochondrion; PM, Plasma membrane; b, bacterium. Bar = 500 nm. This experiment was repeated at least two times and at least 6 different leaves were used in each time course.