An example of extract specific changes in gene expression. A heat map of expression values of 55 significantly regulated genes (p < 0.05 after Bonferroni correction) in a contrast between control (n = 4) and the USA samples (n = 4) but not in the contrast between control (n = 4) and all other Equisetum samples (n = 12). Samples were averaged to yield 3 groups according to the clustering in Figure 6A. The expression values (log2 transformed) were scaled to the row mean. The color key relates the heat map colors to the standard score (z-score), i.e. the deviation from row mean in units of standard deviations above or below the mean. The gene symbols or (for transcripts without gene symbol) Ensembl identifiers  are listed.