Fig. 4
Primary and secondary metabolites with significant differential accumulation in the apoplastic wash fluid collected from the lettuce genotypes Green Towers (GT), Lollo Rossa (LR), and Red Tide (RT) at 1- and 7-days post inoculation with Escherichia coli O157:H7 (Ec) or Salmonella enterica ser. Typhimurium 14028s (Se). Raw peak heights were normalized with the Log10 transformation and auto-scaling functions and subjected to Student´s t-test pair-wise comparisons (bacterium vs. mock) to identify differentially accumulated metabolites (DAMs) through the MetaboAnalyst5.0 software. DAMs were determined as those having a p-value < 0.05 and a Log2 fold change (FC) ≤ − 1 or ≥ 1. White boxes represent not significant net accumulation. Heatmap was created with the heatmap.2 R package using default settings