Figure 1.

Schematic overview of combining global metabolome- and the two tracer labeling experiments. Example isotope patterns for three truly wheat-derived metabolites are shown. Deoxy-(methylthio) adenosine is a plant metabolite and is therefore detected in the GML experiment. As it is neither a compound of the Phe- or Trp-pathways it is only present as the native isotopic form (shown in green) but not as the tracer-derived isotopically labeled form. On the contrary, feruloylquinic acid is derived from Phe and is subsequently detected as the native and labeled form in the Phe-TL approach as well as in the GML approach. Similar to this, glutamyltryptophan is a metabolite derived from Trp and therefore present as both forms in the Trp-TL and the GML approach. In contrast, diisobutylphtalate is a plasticizer that is frequently detected as a contaminant but is not a plant metabolite and therefore not detected in the SIL-assisted setup.