Figure 6.

Experimental design. (A) Tests on treated grapevine plants. Elicitors or water (control) were sprayed onto the whole plants, at time D0, and then the plants were separated into three sets for further analysis. a) A first set of plants was placed into containments 1, 3, and 5 days after treatment (D1, D3, D5) for VOC sampling. At each of these time points, stir bars were installed in the foliage for 4 h. At the end of the experiment (D5), leaves were picked up to measure leaf area. b) A second set of plants served for stilbene quantification; leaves were detached on D1, D2, D4, D6, and D8. c) A third set was used to assess elicitor-induced resistance against downy mildew. The lower side of the leaves was inoculated with a suspension of Plasmopara viticola (Pv) sporangia on D2, and the sporulating leaf area was measured on D7. (B) Photographs of containment devices used for VOC collection. Plants were either bagged individually (1 plant/bag) or gathered under a sealed tent (six plants/tent) in the presence of VOC sensors.