Screening and Identification of Potential Abscisic Acid Catabolites by Chemical Labeling-Assisted Ultrahigh-Performance Liquid Chromatography Coupled with High-Resolution Mass Spectrometry

In this study, a screening strategy was established based on ultrahigh-performance liquid chromatography coupled with high-resolution mass spectrometry assisted by chemical isotope labeling (CIL-UPLC-HRMS) for screening and identifying abscisic acid (ABA) catabolites. Based on the structures of known ABA catabolites, this strategy first proposed the structures of catabolites to be discovered. Afterward, a pair of isotope reagents N,N-2-dimethylaminoethylamine (DMED) and d(4)-DMED were used as labeling reagents to label the carboxyl groups in ABA and its catabolites. Then, the mass-to-charge ratio (m/z) of DMEDand d(4)-DMED-labeled ABA catabolites was calculated based on the labeling schema. In light of the characteristic fragmentation patterns of the DMED-labeled standards of ABA and its catabolites, screening criteria were formulated. Using our strategy, ABA, tABA, and 18 ABA catabolites were identified from seven plant samples. Of the identified catabolites, 16 were known, and to our knowledge, 2 were previously unidentified. Our findings contribute to ABA catabolic network improvement.

Automated summary

In this study, a screening strategy was established based on CIL-UPLC-HRMS for screening and identifying ABA catabolites. By proposing the structures of catabolites to be discovered and using chemical isotope labeling, ABA and its catabolites were successfully identified, including two previously unidentified catabolites.