Figure 5Fungal species are the main drivers ofS. meliloti core genome transcriptional response . Principal Component Analysis (PCA) of the expression profiles from stimulons of strains grown in the presence of the four fungal spent media. The clustering is based on a) up-regulated and b) down-regulated DEGs (2-fold change in expression and padj < 0.01) belonging to the core sets. The first two components explain respectively the 55.45% and 53.05% of the total variance.