Figure 9.

P. syringae–Induced MeSA Formation but Not SAR Is Dependent on Bacterial Production of the Phytotoxin Coronatine.

(A) MeSA emission from Col-0 leaves after inoculation with coronatine-producing Pst, coronatine-deficient Pst cor⁻, and MgCl₂ infiltration. Volatiles were sampled from 0 to 24 HAI, and mean values of ng emitted substance g⁻¹ leaf FW h⁻¹ (±sd, n = 7) are given. Different letters symbolize statistically significant differences between treatments (P < 0.002).

(B) SAR induction by Pst and Pst cor⁻ in Col-0 plants. 1° leaves were infiltrated with MgCl₂, Pst, or Pst cor⁻ (OD 0.01 each), 2° leaves were challenge-infected 2 d later with Psm (OD 0.002), and quantities of Psm in 2° leaves were determined another 3 d later (see Figure 5C for details). Bars represent means (±sd) of cfu per cm² from at least six parallel samples. Different characters symbolize statistically significant differences between treatments (P < 0.01).