Fig. 4

ieb35 peptide induced a weaker plant immune response than that of BcIEB1. a A chart showing the ieb35 motif in BcIEB1 protein. b ieb35 induced a lower level of NbPTI5 expression than BcIEB1. The 5-week old N. benthamiana plants were infiltrated with ieb35 and BcIEB1 at the concentration of 1 µM. Total RNA was extracted and subjected to qPCR assay to analyze the expression of NbPTI5 (mean ± SD, Student’s t-test; ***, P < 0.001). c BcIEB1 induced a stronger hypocotyl growth inhibition effect than ieb35 on Arabidopsis seedlings. Wild-type Col-0 plants were vertically grown on 1/2 MS agar plates in the dark with addition of different concentrations of BcIEB1 or ieb35, and hypocotyl length were photographed 6–7 days later. Scale bars: 1 cm. d BcIEB1 induced a stronger plant growth inhibition than ieb35. Wild-type Col-0 plants were germinated on 1/2 MS agar plates and transfered to liquid 1/2 MS medium with the addition of different concentrations of BcIEB1 or ieb35. Fresh weight was measured and calculated 5 d later (mean ± SD, n ≥ 6, different letters indicate significant difference at P < 0.05, one-way ANOVA followed by Tukey's post hoc test). e BcIEB1 induced stronger resistance to P. capsici than ieb35 in N. benthamiana. Leaves of N. benthamiana were infiltrated with different concentrations of ieb35 or BcIEB1-His (1 μM) for 1 d. The treated leaves were inoculated by P. capsici strain LT263 and photographed under UV light 36–48 h later. Scale bars: 1 cm. The experiments were performed three times with similar results