Figure 1. Triple mutant lym1/lym2/lym3 normally responds to chitin oligosaccharide and generates reactive oxygen species. The leaf discs from 7-wk-old Arabidopsis plant were pre-incubated overnight in fresh MGRL medium containing 1% sucrose in a 48-well microtiter plate.¹¹ The medium was replaced with fresh MGRL medium at 2 h before the (GlcNAc)₇ or water treatment. After the elicitor treatments, the ROS released by Arabidopsis leaves were quantified by chemiluminescence method with luminol. ROS generation was represented as accumulation for 30 min (left) and 60 min (right) after the treatment of water or 50 μg/ml (GlcNAc)₇. Data are shown as means of six leaf discs ± SD. The asterisks indicate statistical significance from the water controls by Student’s t test (p < 0.01). The experiment was repeated twice with the similar results.