Figure 10
A possible role for stilbenes in the restriction of P . viticola development by thiamine treatment. Vitis vinifera cv. Chardonnay plants were treated with water or thiamine for 24 h and inoculated by spraying P. viticola sporangia suspension (104 sporangia/ml). (A) Presence of fluorescent material (discontinued arrows) under autofluorescence corresponding to stilbenes [6], surrounding unbranched and degenerated hyphae (discontinued arrows) of P. viticola in the mesophyll of thiamine-treated plant leaves. (B) Absence of stilbenes accumulation and extensive branching of P. viticola hyphae in the intercellular space of the mesophyll of water-treated plant leaves. (C) Development of necrotic zones (HR) and suppression of P. viticola sporulation in thiamine-treated plants. (D) Development of P. viticola sporulation symptoms in water-treated plants. Bars = 40 μM for (A, B) and 1 cm for (C, D).