Effect of CYP96B22 -silencing in the barley- Bgh interaction. Inoculation of plants with BSMV and grouping into two pools of plants with different expression level of CYP96B22 was done as described for Figure 4. In this case the average silencing efficiency was 79%. Plants of both pools were inoculated with Blumeria graminis f. sp. hordei (Bgh) in a detached leaf assay. Infection sites were categorized according to defense responses associated with the deposition of autofluorescent material. For each leaf 100 infection sites were evaluated at 48 h after inoculation and the mean and standard error of four leaves are presented. Attacked epidermal cells were further investigated for the presence of mature haustoria (see schematic drawing in the lower right corner) and the frequencies are displayed by shading of bars. Cells found with haustoria were summed up as shown in a separate diagram in the upper right corner. Each category of plant defense responses was tested for significant differences between plants with and without silencing using t-test (P < 0.05) and this revealed no significant differences. It was confirmed in an independent experiment that CYP96B22 silencing had no effect on the frequency of haustoria.