15n 2 tryptophan

High-performance liquid chromatography (HPLC) grade acetonitrile, methanol and water were purchased from Burdick & Jackson, NJ. Mass spectrometry grade formic acid was purchased from Sigma- Aldrich, (St Louis, MO). Internal standards namely, [15N]2-Tryptophan, Glutamic acid –d5, Gibberellic acid, Jasmonic acid, Thymine-d4, and Zeatine, were purchased from Sigma- Aldrich, (St Louis, MO). Another internal standard, [15N] Anthranilic acid was purchased from Cambridge Isotope, (Tewksbury, MA). The calibration solution containing multiple calibrants in acetonitrile/trifluroacetic acid/water was purchased from Agilent Technologies, (Santa Clara, CA). The metabolomic analyses of all samples were executed using the protocol described previously [21 (link), 27 (link)–31 (link)]. The raw data (LC-MS output) was normalized using internal standards.

Reagents such as acetonitrile, methanol and water for high-performance liquid chromatography were purchased from Burdick and Jackson. Formic acid and internal standards, which included a mixture of Jasmonic acid, [¹⁵N]₂-Tryptophan, Thymine-d4, Glutamic acid-d5, Gibberellic acid, Trans-Zeatin, [¹⁵N]-Anthranilic acid and Testosterone-d3, were purchased from Sigma-Aldrich. For UDP-N-Acetyl glucosamine quantification, [¹³C]₆ N-acetyl glucosamine was used as an internal standard and the calibration curve for quantification was generated using the purified metabolite purchased from Sigma-Aldrich.