Fig. 4: Strain heterogeneity in the transcriptional response to the disease-relevant condition of growth at 37°C.

A Temperature-dependent (30 °C vs 37 °C) differential expression of 5715 genes (x-axis) in each of 15 strains of A. fischeri (y-axis). The differential expression profiles of strains are clustered hierarchically (left) and their clustering is compared to the strain phylogeny using a tanglegram (right). Strains showed very diverse transcriptional profiles in response to growth at elevated temperatures. Heatmap intensities reflect the log2 fold changes of each gene over all replicates between the two treatment conditions. B Distribution of 204 virulence-associated genes (x-axis) in each of 15 A. fischeri strains (y-axis); the strain phylogeny is shown at the far left. Virulence associated genes are shown as being present and expressed (blue), present and not expressed (black), or not present (white). Heatmap (red) reflects the number of virulence-associated genes expressed in each strain. Gene content clustering is compared to the strain phylogeny using a tanglegram (right). All 204 genes were expressed in at least one strain, and more than half (108) were expressed in all strains. Among the strains, DTO13 showed the most (186) virulence-associated genes expressed and DTO8 the least (162). Expression presence was assessed by the presence of at least ten reads that uniquely align to the gene in at least one sample. Note: strain DTO7 was excluded from transcriptome profiling because of poor growth at 37 °C.