Hierarchical clustering of the expression profiles of VviMAPKKK genes obtained by quantitative RT-PCR analysis in grapevine leaves in response to different biotic and abiotic stimuli. E. necator: powdery mildew infection; SA: treatments with salicylic acid; ETH: treatments with ethylene, H2O2: treatments with hydrogen peroxide; Drought: drought treatments. The heat-map reports the fold-change of relative expression for all VviMAPKKK genes in response to the different treatments, in comparison to their respective controls. Red and green colors represent increased or decreased expression levels, respectively, in comparison to controls, as reported by the scale. Genes were clustered (A, B and C) according to similarities in expression profiles. Details of the treatments are reported in Materials and Methods. Relative expression values for each gene and each treatment are provided in Figures 5, 6, 7, 8, 9 and Additional file 8.