Fig. 5: P. viticola development and H2O2 production at inoculation sites in leaf discs of WT and VvPR4b knockout lines as revealed by staining with aniline blue and DAB.

a–d and e–f represent 24 hpi and 72 hpi, respectively. a1–h1 show infected stomata stained with aniline blue under epifluorescence UV-microscopy. a2–h2 show the tissues stained with DAB under bright-field illumination in the field of vision corresponding to (a1–h1). Arrowhead, H2O2 accumulation; gt germ tube, st stomata, sv substomatal vesicle, ph primary hyphae, hy hyphae, sph sporangiophores, sp sporangia