Arabidopsis parp mutants are compromised in basal resistance.
(A) Bacterial population sizes of Pst within leaves. Pst DC3000 strains with or without avrRpt2 were syringe infiltrated into leaf mesophyll at 1×105 cfu/ml and bacterial populations were measured 3 d post-inoculation. Mean ± standard error of mean for one experiment shown. Experiments were performed three times with similar results; * indicates significant difference from Col-0 across the three experiments (ANOVA, Tukey pairwise comparisons, P < 0.05). (B) Flg22-induced callose deposition. Seedlings exposed to 1 μM flg22 for 24 h were fixed and stained with aniline blue to highlight callose deposition. Left panel: representative images of the four genotypes; right panel: data summary for all tested leaves (n = 24 per genotype). * indicates significant difference from Col-0 across the three experiments (ANOVA, Tukey pairwise comparisons, P < 0.05). (C) Seedling growth inhibition due to chronic flg22-induced defense activation. Ratio is weight of individual seedlings grown for 14 d in liquid MS media + 1 μM flg22, divided by mean of seedlings of same genotype grown without flg22 within same experiment (mean ± standard error of mean). * indicates significant difference from Col-0 across the three experiments (ANOVA, Tukey pairwise comparisons, P < 0.05). (D) Flg22-triggered oxidative burst. Reactive oxygen species from leaf discs of the indicated genotype were measured for 30 min after treatment with 1 μM flg22. RLU: relative luminescence units. (E) Pst-induced γ-H2AX accumulation. Arabidopsis plants of the indicated genotype were vacuum-infiltrated with the indicated Pst strain at 1×107 cfu/ml. The level of γ-H2AX in leaf samples from the indicated time points after inoculation was assessed by immunoblot using anti-γ-H2AX antibody. Equivalent loading of lanes was verified using Ponceau S stain. Upper and lower blots are from separate experiments. Similar results obtained in two separate experiments.
