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Figure 3 | BMC Plant Biology

Figure 3

From: Phenotypic and histochemical traits of the interaction between Plasmopara viticolaand resistant or susceptible grapevine varieties

Figure 3

Localization of peroxidase acitivity in infected leaf tissues. POX (blue) have been visualized by transmission light microscopy following TMB staining (a, c, e, g, h). The corresponding P. viticola vegetative structures (red) inside the leaf tissues (green) have been visualized in epifluorescence after aniline blue staining (b, d, f). (a) Stoma of the susceptible hybrid 18048 showing POX at 2 dai. (b) P. viticola mycelium (m) with haustoria (arrowhead) close to the stoma visualized in (a). Autofluorescent red chloroplasts inside the stomata are visible. The picture was obtained by overlapping a surface section (epidermal cells) and a lower section (mesophyll). (c) Epidermal cells of the resistant cv Bianca showing POX on the plasma membrane, that is detached from the wall, and browning under the stoma at 3 dai. (d) Lower section of (c) showing an altered mycelium (m1) intensely coloured, probably due to callose deposition (asterisk), and no haustoria immediately under the browning area and regular vegetative structures of the pathogen (m2) in a surrounding area showing no peroxidase activity. Asterisk indicates callose, S callose in a closed stoma. (e) Leaf tissues of cv 18048 lacking POX at 5 dai. (f) Regular mycelium (m) with haustoria (arrowheads) in the same area. (g) POX in the epidermal walls of the cells surrounding the stomata with sporangiophores (arrows). Hybrid 18100, 5 dai. (h) Detail of a sporangiophore with POX at the exit point. Scale bar = 50 μm.

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