FIG. 5.

Systemic protection against B. cinerea B05 infection by ultrashort peptides in cucumber and Arabidopsis seedlings. (A) The first leaf of cucumber plants (white arrows) was infiltrated with 100 μl of water (MOCK) or 100 μl of a 12.5 μM solution of P1 24 h before inoculation of the second and third leaves with B. cinerea mycelium. Symptoms were assessed 3 to 4 days after infection. (B) Arabidopsis rosette leaves 3 to 4 days after infection with B. cinerea spores. Four leaves from each plant rosette were treated with 100 μl of water (MOCK) or 100 μl of 12.5 μM peptides. Pathogen inoculation was done on nontreated leaves. Three to 4 days later, infected leaves were detached and analyzed. (C) Arabidopsis disease indexes, ranging from 0 (no symptoms) to 3 (severe lesions), were assessed according to the disease symptoms of 48 leaves in three independent experiments. Bars indicate standard deviations. *, significantly different from the other treatments. G-test-based analysis revealed the dependence of the observed disease index and the peptide tested (P ≪ 0.001).