A–C, Analysis of the role of loliolide in HR cell death using Arabidopsis. Concentrations of loliolide (A), SA (B), and JA (C) in Col-0 leaves before (0 h) or after the infiltration with P. syringae pv. tabaci 6605 or 10 mM MgSO4 as a control. D, Conductivity in wild-type and szl1-1 leaves after the infiltration with P. syringae pv. tabaci 6605 in the presence or absence of 300 μM loliolide. E, Bacterial population in wild-type and szl1-1 leaves 3 d after the inoculation with P. syringae pv. tabaci 6605. Values for (A) to (C) are the mean ± sd (n = three replicates), values for (D) are the mean ± sd (n = 12 leaf discs), and values for (E) are the mean ± sd (n = six replicates, t test). Different letters indicate significant differences among treatments (for A–D, P < 0.05, Tukey-Kramer HSD test; for E, P > 0.05, t test). WT, wild type.