Figure 3.

Effects of pretreatment of the defense-related phytohormones, salicylic acid (SA), jasmonic acid (JA), and ethylene (ET), on disease resistance of Arabidopsis thaliana leaves against Rhizoctonia solani Japanese isolates. Four-week-old Arabidopsis plants were sprayed with SA, JA, or ET (1 mM each; final concentration of DMSO was 0.1%). After 48 h, the rosette leaves were detached and put in Petri dishes. Then, mycelium plugs prepared from R. solani grown in PDA medium were inoculated. The left and middle columns were weak or nonvirulent isolates, and the right column was strong virulent isolates, determined by the assay in Figure 1. Photographs were taken at 0, 3, and 5 days post-inoculation (dpi). Plain PDA plugs without fungus were used as a control. The assay was replicated three times.