Figure 2.

The Fd2‐knockout mutant (Fd2‐KO) is defective in pathogen‐associated molecular pattern (PAMP)‐triggered immunity (PTI)‐induced reactive oxygen species (ROS) accumulation. (a) To detect ROS, leaf strips of Nossen and Fd2‐KO plants were treated with 100 nm flg22 (left) or 200 μg/mL chitin (right) in buffer containing luminol and horseradish peroxidase. Luminescence was recorded at the indicated times. fls2 and cerk1 mutants were used as negative controls for flg22 and chitin treatment, respectively. Error bars represent the standard error (SE) (n = 8). (b) The relative transcriptional levels of RbohD (left) and RbohF (right) in 4‐week‐old non‐treated Nossen and Fd2‐KO plants as determined by quantitative real‐time polymerase chain reaction (qRT‐PCR). (c) The induction of FRK1 as indicated by qRT‐PCR in Nossen and Fd2‐KO plants before and after Pseudomonas syringae pv. tomato (Pst) DC3000 [optical density at 600 nm (OD₆₀₀) = 0.0002] inoculation. In (b) and (c), Actin was used as the endogenous control; significance was determined at **P < 0.01 with Student's t‐test, and error bars represent SE (n = 3). Experiments were conducted in triplicate with similar results. dpi, days post‐infection.