Extracts, as prepared for GC-MS analysis (described above), were dried and resolved in 50 μL HCl (0.1 M). Aliquots of 10 μL were derivatized with AccQ-Tag Ultra Reagent Powder (Waters, Milford, CT, United States) according to the manufacturer’s instructions. Derivatized samples were separated by liquid chromatography and amino acids were detected at 260 nm, using a 1290 UHPLC system coupled to a diode array detector (Agilent, Santa Clara, CA, United States) according to Rademacher et al. (2016). Peaks were integrated using the Chemstation software from Agilent and quantified by external standards after normalization to the internal standard norvaline, added prior to derivatization and the amount of extracted plant material.
