Figure 1.

Summary of the pipeline to feed, detect, and positively identify metabolites derived from an isotopically labeled precursor. A, [¹³C₆]-Phe and [¹²C]-Phe are fed to biologically equivalent stem tissue. B, Metabolites are extracted and separated on LC–MS and peaks are identified with XCMS. All peaks are scanned for MS features consistent with an incorporated [¹³C₆]-Phe. C, Peak-pairs are identified. M301T200 (named as such because it has a [M-H]⁻  m/z of 301 and retention time of 200 s) is a Phe-derived feature because: (1) At 200 s, a peak 6 Da larger than M301 (red color and named M307T200) is detected in [¹³C₆]-Phe-fed tissue. (2) M307T200 in [¹³C₆]-Phe-fed tissue is significantly more abundant than M307T200 in [¹²C]-Phe-fed tissue. Sketch of Arabidopsis stem was downloaded from FigShare (Bouché, Frédéric [2018]: https://doi.org/10.6084/m9.figshare.7159949.v1).