Induction of the tryptophan pathway during the interaction between B. distachyon and F. graminearum . A: Reconstructed tryptophan pathway in B. distachyon. The accession numbers of B. distachyon genes encoding enzymes potentially involved in the metabolic pathway and exhibiting a differential expression between the conditions used for transcriptome analyses are indicated over or next to each arrow (for more information see Additional file 4). B: Metabolic profiling of soluble secondary metabolites from B. distachyon spikelets 96 h after infection by the F. graminearum Fg don+ strain. HPLC profiles were obtained from aqueous methanolic extracts. Chromatograms were analysed by UV detection at 280 nm. For a correspondence of peak numbers, see Additional file 5. C: Relative quantification of metabolites derived from the tryptophan pathway (different letters indicate significance of the difference between conditions; t-test p-value ≤ 0.02).