ABA Quantification in Sugarcane Samples

ABA and ABA catabolites detection and quantification were performed as reported in Diretto et al. (2020) (link) and Barja et al. (2021) (link). Briefly, 50 mg freeze-dried grounded cane samples were extracted using unbuffered Tris-ethyl acetate as reported before (Welsch et al., 2008 (link)). LC-HRMS was carried out using an Ultimate UHPLC system with a photodiode array detector (Dionex), and a Q-exactive quadrupole Orbitrap mass spectrometry system (Thermo Fisher Scientific; LC-HRMS) equipped with an electrospray ionization (HESI) source, operating in negative ion mode, as previously described (Di Meo et al., 2019 (link)) with the following modifications: with nitrogen as sheath and auxiliary gas set at 35 and 25 units, respectively. The vaporizer and capillary temperatures were set at 280 and 320°C, respectively. The discharge current was set to 4.0 μA and S-lens RF level set at 50. Internal standard-based quantification was carried out using the MS data, while retention times and MS2 fragmentation patterns were used for ABA identification by using authentic reference standards (trans-ABA from OlChemIm and ()-ABA from Sigma, St. Louis, MO, United States).