Fig. 4.

Root-mediated signal transmission of systemic acquired resistance against the foliar pathogen P. syringae pv. tabaci (Pta) (A) Schematic representation of the experimental design. (B) Number of bacterial spots measured at 7 d after challenge with 10⁸ cfu mL^–1 Pta in plants pre-treated with 0·33 mM BTH. (C) The bacterial cell count was measured 3 and 6 d after pathogen inoculation. Bars represent the mean ± s.e.m. (sample size, n = 5 replications per treatment). Different letters indicate significant differences between treatments (P = 0·05 according to least significant difference). The experiment was repeated three times with similar results.