This study aimed to comprehensively examine the interface between primary and secondary metabolites in oval- and rectangular-shaped Chinese cabbage (Brassica rapa ssp. pekinensis) using gas chromatography coupled with time-of-flight mass spectrometry (GC-TOFMS) and high-performance liquid chromatography (HPLC). In addition to differences in shape, there was significant morphological variation between the two cultivars. The rectangular variety had greater height and deeper green color, whereas the oval variety had more leaves and greater width. A total of 42 primary metabolites identified by GC-TOFMS were subjected to partial least-squares discriminant, which indicated significant differences in the primary and secondary metabolisms of the two cultivars. Furthermore, total glucosinolate and phenolic contents were higher in the oval cultivar, whereas the rectangular cultivar contained a higher level of total carotenoids. This metabolome study comprehensively describes the relationship between primary and secondary metabolites in the oval and rectangular cultivars of Chinese cabbage and provides information useful for developing strategies to enhance the biosynthesis of glucosinolates, phenolics, and carotenoids in Chinese cabbage. Additionally, this work highlights that HPLC and GC-TOFMS-based metabolite profiling is suitable techniques to determine metabolic differences in Chinese cabbage.
Keywords: Brassica rapa ssp. pekinensis; Chinese cabbage; carotenoid; glucosinolate; phenolics; primary metabolite; secondary metabolite.