An Integrated Metabolomics Study of Glucosinolate Metabolism in Different Brassicaceae Genera

Abstract

Glucosinolates are a group of plant secondary metabolites that can be hydrolyzed into a variety of breakdown products such as isothiocyanates, thiocyanates, and nitriles. These breakdown products can facilitate plant defense and function as attractants to natural enemies of insect pests. As part of the diet, some of these compounds have shown cancer-preventing activities, and the levels of these metabolites in the edible parts of the plants are of interest. In this study, we systematically examined variations in glucosinolates, their precursors, and their breakdown products in 12 commonly consumed vegetables of the Brassicaceae family with gas chromatography—quadrupole time-of-flight mass spectrometer (GC-Q-TOF/MS), liquid chromatography–quadrupole time-of-flight mass spectrometer (LC-Q-TOF/MS), and liquid chromatography—triple quadrupole mass spectrometer (LC-QQQ/MS), using both untargeted and targeted approaches. The findings were integrated with data from literature to provide a comprehensive map of pathways for biosynthesis of glucosinolates and isothiocyanates. The levels of precursor glucosinolates are found to correlate well with their downstream breakdown products. Further, the types and abundances of glucosinolates among different genera are significantly different, and these data allow the classification of plants based on morphological taxonomy. Further validation on three genera, which are grown underground, in damp soil, and above ground, suggests that each genus has its specific biosynthetic pathways and that there are variations in some common glucosinolate biosynthesis pathways. Our methods and results provide a good starting point for further investigations into specific aspects of glucosinolate metabolism in the Brassica vegetables.

Identification of distinctive physiological and molecular responses to salt stress among tolerant and sensitive cultivars of broccoli (Brassica oleracea var. Italica)

“…2 A and B). Methionine (Met) is a precursor of aliphatic glucosinolates [ 34 ]. The salt sensitive cultivars showed increased amounts of Met under salt stress, but the level was stable for the tolerant cultivars (Fig.…”

Potential Arabidopsis thaliana glucosinolate genes identified from the co-expression modules using graph clustering approach

“…The GSL regulatory network would affect several GSL biosynthetic pathways that can be grouped into side-chain elongation, core structure synthesis, co-substrate pathways, and side chain modification ( Harun et al, 2020 ). GSL degradation refers to the formation of activated GSL products that are known to confer protection in plants against the biotic, and abiotic stresses ( Halkier & Gershenzon, 2006 ; Liu et al, 2020 ). There are also five known GSL transporters in the gene network: BAT5, SULTR1;1, SULTR1;2, GTR1, and GTR2.…”

“…The myrosinase enzymes (TGG, EC 3.2.1.147) facilitates the production of active GSLs (bioactive isothiocyanates, nitriles, thiocyanates, and epithionitriles) in damaged plant cells during pest attacks or food preparation. Such activated GSL products have protective roles in plants against the biotic and abiotic stresses ( Halkier & Gershenzon, 2006 ; Liu et al, 2020 ). The variations of the products are based on the GSLs side chain composition and the involvement of the myrosinase interacting proteins in the GSL-myrosinase system ( Wittstock et al, 2016 ; Chhajed et al, 2019 ).…”

Light Intensity Plays Contrasting Roles in Regulating Metabolite Compositions in Choy Sum (Brassica rapa var. parachinensis)

“…PC3 (13.0%) could only stand for the generation of 4-MGBS from GBS, based on all of the loading directions (Figure 6E,F). 50 Moreover, the ellipse at 95% confidence displayed that choy sum on Days 14 and 16 under 400 μmol/ (m 2 •s) tended to synthesize more GTP, NGBS, and 4-OHGBS. However, choy sum on Day 28 under 200 μmol/(m 2 • s) tended to synthesize more aromatic GLS compared with that on Day 30, which accumulated more 4-OHGBS instead (Table 1) (Figures 5D and 6F).…”