Figure 10
Scanning Electron Microscopy (SEM) images of leaf disks infected with Plasmopara viticola zoospores in presence/absence of NoPv1. (a–c) Grapevine leaf disks infected with a P. viticola sporangial suspension (1 × 105 sporangia ml−1) were incubated for 6 h in the dark at 22 °C, (f, flagellum). (d–f) Identical grapevine leaf disks were infected with a P. viticola sporangial suspension (1 × 105 sporangia ml−1) in presence of 200 μM NoPv1 and incubated for 6 h in the dark at 22 °C. All leaf disks were then fixed, covered with gold and observed with a LEO 1430 scanning electron microscope. NoPv1-treated zoospores were unable to develop a proper germ tube and to penetrate the stomatal cavity of grapevine leaf disks. In (f), the black arrow indicates a germ tube primordium that points in the opposite direction with respect to the nearest stomata (asterisk), suggesting that NoPv1-treated zoospores are also unable to sense stomata proximity. In total, about 250 zoospores with and without NoPv1 were observed. The analysis was carried out twice, using 12 independent leaf disks.
