HvWRKY gene expression upon infection with Blumeria graminis (Bgh). Normalized signal intensities of 23 probesets representing HvWRKY genes are displayed for microarray experiments BB4 and BB7 (according to BarleyBase [27, 28]). Experimental samples and timepoints are indicated on the x-axis. Mlo, mlo5 and Mla1 represent different barley genotypes, Bgh_5874 represents a particular strain of powdery mildew (see BarleyBase [27, 28] for experimental details). Fold changes compared to the control (BB7) or timepoint zero (BB4) are color coded as indicated. HvWRKY gene probesets are arranged according to WRKY groups 1 to 3. Several probesets representing the same gene are named _a to _c.