Fig. 4.

Initial Empoasca sp. feeding induces jasmonate accumulation and is triggered by JA signaling capacities. (A and B) Twenty-five Empoasca sp. were caged on N. attenuata WT leaves, and jasmonate accumulation was measured. OPDA and JA levels were measured in control and attacked leaves 24 h after Empoasca sp. feeding. Bars represent average ± SE; n = 4. Asterisks represent significant differences compared with control plants. **P < 0.01; ***P < 0.001; Student’s t test. (C and D) In glasshouse bioassays, MeJA treatment of leaves enhances the resistance to Empoasca sp. attack of WT (control) and ir-lox3 plants but not of ir-coi1 and 35S-jmt1 plants. Leaves of WT, ir-lox3, ir-coi1, and 35S-jmt1 plants were treated with lanolin or with lanolin containing MeJA. (C) Two days after the treatment, plants were challenged with 150 Empoasca sp. adults, and damage was recorded after 7 d. Damage is shown as the percentage of canopy area; data shown are average ± SE; n = 15–18. Different letters indicate statistically significant differences. P < 0.05; Student’s t test. (D) Levels of MeJA, JA, JA-Ile, and OPDA were quantified in MeJA-treated leaves of WT, ir-lox3, ir-coi1, and 35S-jmt1 plants 3 d after the treatment (Table S4). Data shown are average ± SE; n = 4–9. Different letters indicate statistical significance among lines and within analytes. P < 0.05; Student’s t test. nd, not detected. (E) To analyze JA signaling capacities, we determined the levels of trypsin PI activity in lanolin- and MeJA-treated leaves 3 d after the treatment (average ± SE; n = 6). Different letters indicate statistically significant differences. P < 0.05; Student’s t test. nd, not detected.