A. The anionic channels inhibitor glibenclamide (Gli, 200 μM) blocked the plasma membrane depolarization triggered by PS3 in grapevine cell suspensions revealed by the DIBAC₄ probe fluorescence. B. Sporulating areas indicate that Gli blocked the PS3-IR to P. viticola in grapevine leaf discs. Leaf discs were treated during 24 h with Gli (200 μM), washed and then treated with 2.5 g l⁻¹ PS3 during 24 h, washed and, finally inoculated with P. viticola. Leaf sporulating area evaluated at 8 dpi. Different letters indicate statistically significant differences (P<0.05; ANOVA followed by LSD test). Data are representative of three independent experiments (n = 3). C. Microscopic analyses on the same grapevine leaf discs show that Gli inhibits the primed H₂O₂ production (black arrows) and callose deposition (white arrows) during PS3-IR, leading to P. viticola spreading. Aniline blue and DAB staining were realized to detect callose and H₂O₂, respectively. Pictures are representative of three independent experiments. Bar = 100 μm.

https://doi.org/10.1371/journal.pone.0194327.g001