flg22-dependent enhancement of AtPep-triggered ROS is independent of the abundance of PEPR1 or PEPR2 and the added AtPep peptide. A, B, E, and F, ROS production. Leaf discs of the indicated genotypes (A, E, and F) or Col-0 (B) were either pretreated with 1 µm flg22 or without any peptide (control) for 16 h and then treated with 1 µm of the indicated peptide or without any peptide (control). Columns represent averages of the peak values of ROS production of 12 biological replicates. Error bars show se of the mean. C and D, Ethylene production. Leaf discs of Col-0 and two independent transgenic lines expressing either 35S::PEPR1::yellow fluorescent protein (P1-Ox-A.II and P1-Ox-F.II) or 35S::PEPR2::yellow fluorescent protein (P2-Ox-c.2 and P2-Ox-f.2) were floated on water for 16 h, then treated with the indicated elicitors and incubated for 4 h before measurement. Columns represent the mean of six independent replicates. Error bars show se of the mean. Asterisks represent Student’s t test results (*P < 0.05, **P < 0.01, ***P < 0.001). RLU, Relative light units.