A Comparative Metabolomics Study of Glucosinolates in Four Watercress (Nasturtium officinale R. Br.) Samples from Different Origins Using Ultra-High-Performance Liquid Chromatography–Electrospray Ionization–Tandem Mass Spectrometry

Glucosinolates are important plant secondary metabolites that are involved in plant defense responses and have beneficial effects on human life and health. Watercress (Nasturtium officinale R. Br.) is an aquatic vegetable rich in glucosinolates. This study utilized ultra-high-performance liquid chromatography–electrospray ionization–tandem mass spectrometry (UHPLC-ESI-MS/MS) to compare and analyze four watercress samples from different origins. A total of 35 glucosinolates were identified, including 33 differential glucosinolates, and their relative content in different samples was determined. Differential metabolite screening revealed significant differences in the watercress from Guangdong, China (GD), compared with other samples. It contained two specific glucosinolates: 2(R)-Hydroxy-2-Phenylethyl glucosinolate and 4-Benzoyloxybutyl glucosinolate. The watercress from the United States of America (MG) had the highest total glucosinolate content. Genes involved in glucosinolate biosynthesis, such as NoCYP83A1 and NoSUR1, were also expressed differently in the four samples. This study provides a reference for further investigation of glucosinolate metabolites in the four watercress samples and the utilization of glucosinolates in watercress.