OsPIP2;2 links PAMP-induced apoplastic H2O2 to the PTI pathway. A, Chronological changes in the H2O2-probing AR fluorescence densities in leaves of 2-week-old rice seedlings after flg22 treatment (means ± SEM, n = 8). OE#1, OsPIP2;2OE#1; OE#2, OsPIP2;2OE#2; KO#41, Ospip2;2#41; KO#279, Ospip2;2#279. B, Cell imaging of the DCF fluorescence by laser confocal microscopy. Leaves were preloaded with H2DCF-DA 45 min before treatment with 300 μM H2O2. C, flg22-induced callose deposition in rice. The leaves of 2-week-old rice seedlings were treated with 10 μM flg22 for 16 h and then stained by aniline blue. B and C, The scale bar representing 100 μm applies to all the images. D, Quantification of callose deposition in leaves in C by ImageJ. Data were shown as means ± SEM (n = 3). E, MAPK activation was detected after flg22 treatment by western blot. The expected identities of the respective bands are marked on the right. The experiment was performed twice with similar results. F–H, Expression levels of pathogenesis-related genes OsPR1a and OsPR10 expression levels in plants with PXO99A, RS105, or HB3 24 h postinoculation. Data are shown as means ± SEM (n = 4). Lowercase letters indicate significant differences by one-way ANOVA and Duncan’s multiple range tests (at P ≤ 0.01).