Figure 7
Clustering and qPCR analysis of the marker genes. (A) The expression of eight O3-inducible genes and the qPCR normalization gene Actin-2 were analyzed in public array data from biotic and abiotic stress and hormone treatments. Red and green indicate increased or decreased expression compared to untreated plants, respectively. The intensity of the colours is proportional to the absolute value of the fold difference. (B) Markers genes for O3 responses were analyzed by qPCR in Col-0 and sid2, npr1, dnd1, ein2 and fad3/7/8 exposed to 250 ppb O3 for 6 h. Samples were harvested at 1 or 8 h (6 h plus 2 h recovery under clean air conditions) after the onset of the O3 treatment. Transcript levels were calculated by comparison of O3-exposed plants with corresponding control plants grown under clean air conditions. An expression level of one indicates no change of expression, increased expression is indicated by values larger than one while decreased expression is shown by values smaller than one. Increase of expression by 2-fold or higher is high-lighted in red and decrease in expression by 2-fold or more in green. NR - no reproducible data could be obtained for this gene. The experiment was repeated four times; fold change was calculated from the average normalized cycle difference of all biological repeats. Statistically significance (Benjamini-Hochberg FDR corrected p-value ≤ 0.1) is indicated with asterisks (see additional file 1).