FIGURE 4.

Calcium and ROS signaling in response to DAMPs. A, cytoplasmic calcium levels rise following stimulation with AtPep1 and flg22. Leaf pieces of apoaequorin-transformed Arabidopsis Col-0 plants were preincubated with coelenterazine and then stimulated with different doses of flg22 and AtPep1. Luminescence was continuously monitored. The traces are the mean of at least 5 individual assays (see supplemental Table S1). Error bars represent S.D. B and C, MAMP- or DAMP-triggered membrane depolarization is independent of ROS production. When mesophyll cells of WT plants (Col-0) were examined in the presence of diphenyleneiodonium (B), a plasma membrane response to indicated elicitors (10 nm) was an elicitor-triggered depolarization. Accordingly, wild type plants, rbohD single mutant and rbohD/F double mutant defected in plasma membrane NADPH oxidase subunit(s) showed wild type membrane responses to 10 nm flg22, 10 nm elf18, and 10 nm AtPep1 (C). In the latter depiction of the amplitudes the error bars represent S.D. calculated from 3 to 6 independent repetitions.