Figure 4.

Effects of pretreatment of the defense-related phytohormones, salicylic acid (SA), jasmonic acid (JA), and ethylene (ET), on disease resistance of Arabidopsis thaliana plants to Rhizoctonia solani Japanese isolates inoculated into soil. Ten-day-old Arabidopsis seedlings grown on ½ MS medium were sprayed with SA, JA, or ET (1 mM each; final concentration of DMSO was 0.1%). Spraying of 0.1% DMSO was used as a control. After 48 h, the seedlings were transplanted into R. solani-inoculated soil. Soil inoculated with plain PDA plugs without fungus was used as a negative control. The R. solani isolates that exhibited strong virulence in this inoculation method as demonstrated in Figure 2 were tested. Photographs were taken at 14 days post-inoculation (dpi). Plain PDA plugs without fungus were used as a control. The assay was replicated three times.