Figure 1.

PARP inhibitor 3AB blocks MAMP-induced callose but not wound- or mekk1-associated callose; PARP inhibitor also does not block MAMP-induced ROS or gene expression responses. A, Callose deposition in 10-d-old Arabidopsis seedlings 24 h after the indicated treatment, except mekk1 mutants were germinated in 3AB and visualized for callose 1 week later. Five-day-old mekk1 seedlings treated with 3AB for 24 h also produce callose (data not shown). B, ROS production in Arabidopsis leaf discs that were treated with 3AB 30 min prior to exposure to 1 μm flg22 (F, left graph) or 1 μm elf18 (E, right graph). ROS production was measured for 30 min immediately after MAMP exposure, using a luminol-based assay, and area under the curve is presented, normalized to the average area for MAMP-treated samples from the same experiment (means ± se are shown for 36 samples from three biological replicates). C, MAMP-induced gene expression, as monitored by semiquantitative RT-PCR for Arabidopsis seedlings treated with or without 2.5 μm flg22 and PARP inhibitor for the indicated time intervals. Similar results were obtained in two biological replicates. untr, Untreated. D, Callose deposition in Arabidopsis seedlings 24.1 h after exposure to 1.0 μm flg22. Some seedlings were also treated with 2.5 mm 3AB at 5 or 24 h after exposure to flg22. Experiment was repeated twice with similar results.