Metabolite Profiling and Comparative Analysis of Secondary Metabolites in Chinese Cabbage, Radish, and Hybrid xBrassicoraphanus

Metabolomics comparison of four varieties apple with different browning characters in response to pretreatment during pulp processing

Browning commonly appeared in apple processing, which varied in different apple varieties. Present work investigated the metabolomics of four varieties apple of Yataka, Gala, Sansa, and Fuji, which possessed different browning characteristics and related enzymes. Sansa as browning insensitive apple variety, exhibited the least chroma change with the lowest PPO activity and the highest SOD activity among the four apple varieties. Browning inhibition pretreatment increased the activity of SOD and PAL and decreased PPO and POD activity. In addition, metabolomic variances among the four apple varieties (FC), their browning pulp (BR) and browning inhibition pulp (CM) were compared. And the key metabolites were in-depth analyzed to match the relevant KEGG pathways and speculated metabolic networks. There were 487, 644, and 494 significant differential metabolites detected in FC, BR and CM, which were consisted of lipids, benzenoids, phenylpropanoids, organheterocyclic compounds, organic acids, nucleosides, accounting for 23 %, 11 %, 15 %, 16 %, 11 % of the total metabolites. The differential metabolites were matched with 39, 49, and 36 KEGG pathways in FC, BR, and CM, respectively, in which other secondary metabolites biosynthesis metabolism was the most significant in FC, lipid metabolism was the most significant in BR and CM, and energy metabolism was markedly annotated in CM. Notably, Sansa displayed the highest number of differential metabolites in both its BR (484) and CM (342). The BR of Sansa was characterized by flavonoid biosynthesis, while the other three apple varieties were associated with α-linolenic acid metabolism. Furthermore, in browning sensitive apple varieties, the flavonoid and phenylpropanoid biosynthesis pathway was significantly activated by browning inhibition pretreatment. Phenolic compounds, lipids, sugars, organic acids, nucleotides, and adenosine were regulated differently in the four apple varieties, potentially serving as key regulatory sites. Overall, this work provides novel insight for browning prevention in different apple varieties.

Volatile/semi-volatile metabolites profiling in living vegetables via a novel covalent triazine framework based solid-phase microextraction fiber coupled with GC-QTOF-MS

An in vivo solid-phase microextraction (SPME) fiber with high-coverage capture capacity of plant endogenous substances based on the porous covalent triazine framework (CTF) material was developed. The CTF fiber coupled with gas chromatographic quadrupole time-of-flight mass spectrometer (GC-QTOF-MS) analysis was used for monitoring untargeted endogenous metabolites in living Chinese cabbage plants (Brassica campestris L. ssp. chinensis Makino (var. communis Tsen et Lee)). A total of 100 endogenous substances were identified, mainly including aldehydes, ketones, acids, alcohols, phenols, alkanes, alkenes, esters, isorhodanates, nitriles, as well as indole and its derivatives. Using the in vivo metabolites analysis method, Chinese cabbage plants at different growing stages demonstrated significantly statistical differences in plant metabolism. In addition, metabolic dysregulation of Chinese cabbage plants under fipronil pesticide contamination was observed. To summarize, the proposed approach provides a feasible method to capture metabolic information in living vegetables and for risk assessment of pesticide use during agricultural production.

Evidence for Criterion-Related Validity of Pressure-Mediated Reflection Spectroscopy for Approximating Fruit and Vegetable Consumption among Preschool Children

BACKGROUND

Skin carotenoids are a valid biomarker for approximating fruit and vegetable consumption (FVC). Veggie Meter® (VM®, Longevity Link Corp.) is a pressure-mediated reflection spectroscopy (RS)-based device that allows for noninvasive and rapid assessment of skin-carotenoid score (SCS) in adults and children. Although VM® is established as a valid tool to measure FVC in adults, there is limited research supporting the validity evidence of the VM® to approximate FVC among preschool children.

OBJECTIVE

The current study aims to assess evidence supporting the criterion-related validity of RS-based SCS for approximating FVC among preschool children (3-5-y old).

METHODS

We collected cross-sectional data from typically developing preschool children (n = 136) attending the Child and Adult Care Food Program-participating family child care home settings (FCCHs) (n = 46) in Nebraska. Research team members collected children's height and weight to calculate body mass index; and measured children's SCS using the VM®. Children's FVC in FCCHs were collected using dietary observation. In addition, parents (n = 89) completed a shortened food frequency questionnaire to report children's FVC at home. Kendall's Tau (τ) correlation tests were conducted to measure the association between children's SCS with FVC in FCCHs and with parent-reported total fruit and vegetable (FV) frequency scores.

RESULTS

Children's SCS were significantly correlated with their mean FVC in FCCHs, τ = 0.14 (P = 0.02), total provitamin A carotenoids intake in FCCHs, τ = 0.19 (P < 0.001), and with parent-reported total FV frequency score, τ = 0.16 (P = 0.04).

CONCLUSION

The correlation coefficients in this study are comparable with results from a meta-analysis examining associations between FVC and SCS in 7-10-y-old children (r = 0.20). Thus, evidence suggests that RS offers a potentially valid, objective, and feasible method to assess preschool children's total FVC in multiple settings, especially in conjunction with other dietary assessment tools.

Metabolite profiles and biological activities of different phenotypes of Chinese cabbage (Brassica rapa ssp. Pekinensis)

Chinese cabbage is considered as one of the most important cruciferous vegetables in South Korea because of its use in salads, kimchi, and Korean cuisine. Secondary metabolites were quantified in three Chinese cabbage varieties: 65065, interspecific hybrid of Chinese cabbage × red cabbage exhibiting a deep purple color; 85772, interspecific hybrid of Chinese cabbage × red mustard exhibiting a reddish-purple color; and a typical Chinese green cabbage cultivar "CR Carotene" (Brassica rapa subsp. pekinensis cv. CR Carotene). A total of 54 metabolites (2 amines, 2 sugar alcohols, 2 sugar phosphates, 6 carbohydrates, 18 amino acids, 13 organic acids, 8 phenolic compounds, and 3 carotenoids) were detected in 85772. Of them, 52 metabolites excluding β-carotene and 9-cis-β-carotene, and 51 metabolites excluding leucine, β-carotene, and 9-cis-β-carotene, were detected in 65065 and CR Carotene, respectively. Amino acid content was the highest in 85772, followed by 65065 and CR Carotene. The cultivars 65065 and 85772 contained high levels of phenolic compounds and total anthocyanins. Cyanidin-, pelargonidin-, and petunidin-type anthocyanins were detected in 65065 and 85772. However, delphinidin-type anthocyanins which typically impart a deep purple color were identified only in the deep purple phenotype 65065. Furthermore, the total anthocyanin content was the highest in 85772 (4.38 ± 0.65 mg g -1 dry weight) followed by that in 65065 (3.72 ± 0.52 mg g-1 dry weight). Antibacterial and antioxidant analyses revealed remarkable antibacterial effects of the purple cultivars against pathogens Vibrio parahaemolyticus (KCTC 2471), Bacillus cereus (KCTC 3624), Pseudomonas aeruginosa (KCCM 11803), Staphylococcus aureus (KCTC 3881), Chryseobacterium gleum (KCTC 2094), and Proteus mirabilis (KCTC 2510)] and methicillin-resistant pathogenic strains of Pseudomonas aeruginosa (0826, 0225, 0254, 1113, 1378, 1731, p01827, and p01828) compared with the antibacterial effects of CR Carotene. Furthermore, 65065 and 85772 exhibited significantly higher antioxidant activity than that of the CR Carotene. Therefore, the novel purple Chinese cabbages (65065 and 85772), derived from interspecific hybridization, are potentially favorable alternatives to the typical green Chinese cabbage, given the higher content of amino acids, phenolic compounds, anthocyanins, and carotenoids, as well as an increased ability to scavenge free radicals and inhibit pathogen growth.

LED Lights Influenced Phytochemical Contents and Biological Activities in Kale (Brassica oleracea L. var. acephala) Microgreens

Light-emitting diodes (LEDs) are regarded as an effective artificial light source for producing sprouts, microgreens, and baby leaves. Thus, this study aimed to investigate the influence of different LED lights (white, red, and blue) on the biosynthesis of secondary metabolites (glucosinolates, carotenoids, and phenolics) and the biological effects on kale microgreens. Microgreens irradiated with white LEDs showed higher levels of carotenoids, including lutein, 13-cis-β-carotene, α-carotene, β-carotene, and 9-cis-β-carotene, than those irradiated with red or blue LEDs. These findings were consistent with higher expression levels of carotenoid biosynthetic genes (BoPDS and BoZDS) in white-irradiated kale microgreens. Similarly, microgreens irradiated with white and blue LEDs showed slightly higher levels of glucosinolates, including glucoiberin, progoitrin, sinigrin, and glucobrassicanapin, than those irradiated with red LEDs. These results agree with the high expression levels of BoMYB28-2, BoMYB28-3, and BoMYB29 in white- and blue-irradiated kale microgreens. In contrast, kale microgreens irradiated with blue LEDs contained higher levels of phenolic compounds (gallic acid, catechin, ferulic acid, sinapic acid, and quercetin). According to the total phenolic content (TPC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition assays, the extracts of kale microgreens irradiated with blue LEDs had slightly higher antioxidant activities, and the DPPH inhibition percentage had a positive correlation with TPC in the microgreens. Furthermore, the extracts of kale microgreens irradiated with blue LEDs exhibited stronger antibacterial properties against normal pathogens and multidrug-resistant pathogens than those irradiated with white and red LEDs. These results indicate that white-LED lights are suitable for carotenoid production, whereas blue-LED lights are efficient in increasing the accumulation of phenolics and their biological activities in kale microgreens.

Chemical Profile of Turnip According to the Plant Part and the Cultivar: A Multivariate Approach

Turnip (Brassica rapa subsp. rapa) is a cruciferous plant cultivated worldwide that serves as a source of nutrients and bioactive compounds. Most turnip studies have focused on a few compounds or on part of the plant. The establishment of a complete chemical profile of different plant parts would facilitate its use for nutritional and medicinal purposes. In the current study, mineral elements, soluble sugars, free amino acids (FAA), total phenols (TP), total flavonoids (TF), and glucosinolates (GS) were quantified in the leaves, stems, and roots. Results were compared for 20 strains of turnip. The outcomes showed significant differences between parts of the plant and strains. The leaves exhibited the highest TF, TP, indispensable FAA, and microelement levels, and they showed a higher GS. Moreover, the stems had a high content of GS and macroelements. Furthermore, the roots showed high levels of free sugars and total FAA. The findings of this work provide the basis for utilizing each part of the turnip plant based on its chemical composition.

Improvement of physicochemical characteristics, flavor profiles and functional properties in Chinese radishes via spontaneous fermentation after drying

Spontaneously dried-fermented radishes have been consumed in China for hundreds of years and are usually fermented for a long time to acquire high quality. In this study, the spontaneously dried-fermented radishes with short-term manufacturing periods were made from five different varieties of radishes that grew in the same environment. In addition, the physicochemical characteristics (i.e., moisture content, soluble solid, and pH value), flavor profiles (i.e., free amino acids, organic acids, and volatile compounds), and functional properties (i.e., total phenolics content, total flavonoids content, sulforaphane content, and γ-aminobutyric acid [GABA] content) of these five raw radishes and spontaneously dried-fermented radishes were analyzed and compared. In detail, the content of volatile and nonvolatile compounds increased, especially in oxalic acid, succinic acid, and umami free amino acids. Furthermore, functional components, such as sulforaphane and GABA, were also enriched via spontaneous fermentation after drying. In addition, the results of principal component analysis, hierarchical clustering analysis, and redundancy analysis showed that there were significant discrepancies appeared when raw radishes were processed via spontaneous fermentation or not. These results suggested that the process of spontaneous fermentation after drying may contribute to improving the quality of fresh radishes. Notably, radishes with red skin and flesh were regarded as exceptional varieties for processing, because of the preferable flavor profiles and affluent functional substances via spontaneous fermentation after drying. Therefore, these findings could deliver a systematical insight into developing processed radishes with high quality. PRACTICAL APPLICATION: The spontaneously dried-fermented radishes were manufactured through the process of spontaneous fermentation after drying, which acquired tasty and healthy characteristics by accumulating the volatile and nonvolatile compounds as well as the functional components, like total phenolics, total flavonoids, sulforaphane, and γ-aminobutyric acid. Importantly, because of the excellent processing properties, the radishes with red skin and flesh could be more appropriate to produce spontaneously dried-fermented radishes. Our findings may provide a practical strategy for developing vegetable relishes with superb flavor profiles and good functional properties in pickled vegetables.

Effects of Chilling Treatment on Baicalin, Baicalein, and Wogonin Biosynthesis in Scutellaria baicalensis Plantlets

When plants are exposed to stressful conditions, they modulate their nutrient balance by regulating their primary and secondary metabolisms to adapt. In this study, changes in primary and secondary metabolites elicited by chilling stress treatment and the effects of treatment duration were examined in roots of Scutellaria baicalensis (S. baicalensis) plantlets. The concentrations of most sugars (maltose, glucose, sucrose, and fructose) and of several amino acids (proline and GABA), which are crucial regarding plant defense mechanisms, increased with increasing duration of chilling stress. Furthermore, salicylic acid levels increased after two-day chilling treatments, which may enhance plant tolerance to cold temperatures. The concentrations of flavones (baicalin, baicalein, and wogonin) increased during chilling stress, and those of phenolic acids (ferulic acid and sinapic acid) increased after two-day chilling treatments. The concentrations of these flavones were positively correlated with sucrose levels which acted as energy sources.

Metabolic Analyses and Evaluation of Antioxidant Activity in Purple Kohlrabi Sprouts after Exposed to UVB Radiation

Various metabolites act as plant defense molecules due to their antioxidant abilities. This study aimed to investigate the influence of UVB irradiation on the accumulation of metabolites, including primary metabolites (sugar, sugar alcohols, amino acids, organic acids, and an amine) and secondary metabolites (anthocyanins, fatty acids, and phenolic acids), and its synergistic antioxidant ability, in purple kohlrabi sprouts. Metabolite analyses revealed a total of 92 metabolites in the sprouts. Specifically, the levels of most amino acids increased after 24 h of UVB treatment, and then slightly decreased in the kohlrabi sprouts. The levels of most sugars and sugar alcohols increased after 24 h of UVB treatment and then decreased. The levels of TCA cycle intermediates and phenolic acids gradually increased during the UVB treatment. Furthermore, the levels of some fatty acids gradually increased during the UVB treatment, and the levels of the other fatty acids increased after 6 h of UVB treatment and then decreased. In particular, the levels of most anthocyanins, known to be strong antioxidants, gradually increased after 24 h of UVB treatment. In the in vitro ABTS scavenging assay, UVB-treated purple kohlrabi sprouts showed increased scavenging ability. This may be attributed to the increased accumulation of metabolites acting as antioxidants, in response to UVB treatment. This study confirmed that UVB irradiation induced the alteration of primary and secondary metabolism in the kohlrabi sprouts.

Gene Expression and Metabolic Analyses of Nontransgenic and AtPAP1 Transgenic Tobacco Infected with Potato Virus X (PVX)

Potato virus X (PVX), a species of the genus Potexvirus, is a plant pathogenic virus that causes severe symptoms such as mild mosaic, crinkling, necrosis, and mottling on leaves. The objectives of the present study were to investigate the effect of PVX virus infection on the metabolic system in nontransgenic and Arabidopsis thaliana production of anthocyanin pigment 1 (AtPAP1) transgenic tobacco using transcript expression analysis and metabolic profiling. Potato virus X inoculation increased the gene expression of phenylpropanoid and flavonoid biosynthesis and the production of chlorogenic acid, p-coumaric acid, benzoic acid, rutin, quercetin, and kaempferol in nontransgenic tobacco leaves. However, in the AtPAP1 transgenic tobacco leaves, PVX inoculation decreased the expression of AtPAP1 and phenylpropanoid and flavonoid biosynthesis genes, and the production of phenolics and anthocyanin also declined. In contrast, the levels of amino acids and tricarboxylic acid (TCA) cycle intermediates increased after infection in the AtPAP1 transgenic plant leaves. To date, these results have not been reported previously. We suggest that PVX infection decreases AtPAP1 expression, leading to the downregulation of phenylpropanoid and flavonoid biosynthesis in transgenic plants.

Metabolic Profiling of White and Green Radish Cultivars (Raphanus sativus)

Radish (Raphanus sativus) is a Brassica vegetable important for human nutrition and health because it is rich in diverse metabolites. Although previous studies have evaluated various metabolites, few studies have comprehensively profiled the primary and secondary metabolites in the roots of white- and green-colored radishes. Thus, this study aimed to provide information about the contents of metabolites beneficial for human health in both cultivars and to investigate the relationships between the various metabolites detected. In particular, among the 55 metabolites detected in radish roots, the levels of most amino acids and phenolic acids, vital to nutrition and health, were higher in green radish roots, while slightly higher levels of glucosinolates were observed in white radish roots—information which can be used to develop an effective strategy to promote vegetable consumption. Furthermore, glutamic acid, as a metabolic precursor of amino acids and chlorophylls, was positively correlated with other amino acids (cysteine, tryptophan, asparagine, alanine, serine, phenylalanine, valine, isoleucine, proline, leucine, beta-alanine, lysine, and GABA), and chlorophylls (chlorophyll a and chlorophyll b) detected in radish roots and phenylalanine, a metabolic precursor of phenolic compounds, were positively correlated with kaempferol, 4-hydroxybenzoate, and catechin. In addition, strong positive correlations between carbohydrates (sucrose and glucose) and phenolics were observed in this study, indicating that sucrose and glucose function as energy sources for phenolic compounds.

Identifying Key Metabolites Associated with Glucosinolate Biosynthesis in Response to Nitrogen Management Strategies in Two Rapeseed (Brassica napus) Varieties

A high glucosinolate (GSL) concentration, an undesirable substance, has severely restricted rapeseed (Brassica species) development. We performed widely targeted metabolomics analysis based on the ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) technology to analyze the metabolic profiles and identify the differential metabolites and GSL components in response to different nitrogen (N) levels in two rapeseed varieties. A total of 341 metabolites and 38 GSL components were detected in the seeds. A total of 188 differential metabolites, including 34 GSL components, were identified in response to different treatments, which were mapped into 2-oxocarboxylic acid metabolism, tryptophan metabolism, and GSL biosynthesis. Key indicators of GSL components highly responsible for different N levels under two contrasting varieties were recognized, i.e., 1-methylpropyl GSL and 4-methylthiobutyl GSL. This study suggests that the efficient N management and variety selection are important strategies for developing rapeseed with low GSLs.

Tissue-specific distribution of primary and secondary metabolites of Baemoochae (×Brassicoraphanus) and its changes as a function of developmental stages

The distribution and changes in the primary and secondary metabolite profiles of Baemoochae, an inter-generic hybrid of Chinese cabbage and radish, during the plant's developmental stages were investigated. Metabolites were analyzed using gas chromatography-mass spectrometry (GC-MS) and ultra-high-performance liquid chromatography-electrospray ionization-quadrupole time-of-flight (UHPLC-ESI-qTOF MS). Free sugar, organic acid, and amino acid composition depended on the tissue type and developmental stage of Baemoochae. For example, glucose and alanine levels were higher in mature leaves than in young leaves; citric acid content in mature roots was lower than that in young roots. Several glucosinolates were identified for the first time in Baemoochae. Glucoraphasatin was predominant in both leaves and roots, regardless of plant maturity. Total glucosinolate content was significantly higher in roots than in leaves and in mature than in young plants. The roots of mature Baemoochae could be used as a rich source of glucosinolates, with several potential health-promoting effects.

Proteomic insights into protostane triterpene biosynthesis regulatory mechanism after MeJA treatment in Alisma orientale (Sam.) Juz

Protostane triterpenes in Alisma orientale (Sam.) Juz. have unique structural features with distinct pharmacological activities. Previously we have demonstrated that protostane triterpene biosynthesis could be regulated by methyl jasmonate (MeJA) induction in A. orientale. Here, proteomic investigation reveals the MeJA mediated regulation of protostane triterpene biosynthesis. In our study, 281 differentially abundant proteins were identified from MeJA-treated compared to control groups, while they were mainly associated with triterpene biosynthesis, α-linolenic acid metabolism, carbohydrate metabolism and response to stress/defense. Key enzymes 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), squalene epoxidase (SE), oxidosqualene cyclase (OSC) and cytochrome P450s which potentially involved in protostane triterpene biosynthesis were significantly enriched in MeJA-treated group. Basic Helix-loop-helix (bHLH), MYB, and GRAS transcription factors were enhanced after MeJA treatment, and they also improved the expressions of key enzymes in Mevalonate pathway and protostane triterpene. Then, MeJA also could increase the expression of α-galactosidase (α-GAL), thereby promoting carbohydrate decomposition, and providing energy and carbon skeletons for protostane triterpene precursor biosynthesis. As well, exogenous MeJA treatment upregulated 13-lipoxygenase (13-LOX), allene oxide synthase (AOS) and allene oxide cyclase (AOC) involved in α-linolenic acid metabolism, leading to the accumulation of endogenous MeJA and activation of the protostane triterpene biosynthesis transduction. Finally, MeJA upregulated stress/defence-related proteins, as to enhance the defence responses activity of plants. These results were further verified by quantitative real-time PCR analysis of 19 selected genes and content analysis of protostane triterpene. The results provide some new insights into the role of MeJA in protostane triterpene biosynthesis.

Metabolic Analysis of Root, Stem, and Leaf of Scutellaria baicalensis Plantlets Treated with Different LED Lights

Light emitting diodes (LEDs) have recently been considered an efficient artificial light source in plant factories for enhancing plant growth and nutritional quality. Accordingly, this study aimed to review blue, red, and white LED light sources for efficiency and length of the growing period to produce seedlings of Scutellaria baicalensis with high nutritional value. The roots, stems, and leaves of S. baicalensis seedlings were grown under different LED lights and harvested after two and four weeks, and analyzed using high-performance liquid chromatography and gas chromatography time-of-flight mass spectrometry to identify and quantify primary and secondary metabolites. Roots, particularly in the seedlings treated with white LEDs were determined to contain the greatest concentrations of the representative compounds present in S. baicalensis: baicalin, baicalein, and wogonin, which show highly strong biological properties compared to the other plant organs. A total of 50 metabolites (amino acids, sugars, sugar alcohols, organic acids, phenolic acids, and amines) were detected in the roots, stems, and leaves of S. baicalensis seedlings, and the concentrations of primary and secondary metabolites were generally decreased with the increasing duration of LED illumination. Therefore, this study suggests that white LED light and a 2-week growing period are the most efficient conditions for the production of baicalin, baicalein, and wogonin.

Metabolic profiling and antioxidant activity during flower development in Agastache rugosa

Our previous study showed that flowers of Agastache rugosa had higher phenolic levels and higher antibacterial and antioxidant capacity compared to those of the leaves and stems. The aim of this study was to provide information on the variation in primary and secondary metabolites during flower development in A. rugosa by using high performance liquid chromatography (HPLC) and assays of total anthocyanin (TAC), flavonoid (TFC), and phenolic content (TPC), as well as gas chromatography time-of-flight mass spectrometry (GC-TOFMS) analysis. Assays of TPC, TAC, and TFC showed that the floral bud (stage I) contained higher TPC than did the partially open flower (stage II) and fully open flower (stage III). However, the TFC was the highest at stage II, and the highest TAC was observed at stage III. Furthermore, HPLC analysis revealed that the level of total phenylpropanoids, including rosmarinic acid, tilianin, acacetin, 4-hydroxybenzoic acid, caffeic acid, chlorogenic acid, trans-cinnamic acid, rutin, (-)-epicatechin, quercetin, and kaempferol, was higher in stages I and II, but the concentrations of rutin and rosmarinic acid were highest in stage III. A total of 43 compounds, including amino acids, organic acids, phenolic compounds, sugars, photorespiration-related compounds, and intermediates of the tricarboxylic acid cycle, were identified through GC-TOFMS analysis. Of these compounds, most amino acids decreased during flower development. In contrast, the increase in concentrations of glucose and sucrose were observed from stages I to III. In this study, health-beneficial compounds were identified and quantified in flowers of A. rugosa. Accordingly, our results suggests that A. rugosa flowers can potentially be used as biomaterials for pharmaceuticals, cosmetics, food, and related industries.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at (10.1007/s12298-021-00945-z).

Profiles of Secondary Metabolites (Phenolic Acids, Carotenoids, Anthocyanins, and Galantamine) and Primary Metabolites (Carbohydrates, Amino Acids, and Organic Acids) during Flower Development in Lycoris radiata

This study aimed to elucidate the variations in primary and secondary metabolites during Lycorisradiata flower development using high performance liquid chromatography (HPLC) and gas chromatography time-of-flight mass spectrometry (GC-TOFMS). The result showed that seven carotenoids, seven phenolic acids, three anthocyanins, and galantamine were identified in the L. radiata flowers. Most secondary metabolite levels gradually decreased according to the flower developmental stages. A total of 51 metabolites, including amines, sugars, sugar intermediates, sugar alcohols, amino acids, organic acids, phenolic acids, and tricarboxylic acid (TCA) cycle intermediates, were identified and quantified using GC-TOFMS. Among the hydrophilic compounds, most amino acids increased during flower development; in contrast, TCA cycle intermediates and sugars decreased. In particular, glutamine, asparagine, glutamic acid, and aspartic acid, which represent the main inter- and intracellular nitrogen carriers, were positively correlated with the other amino acids and were negatively correlated with the TCA cycle intermediates. Furthermore, quantitation data of the 51 hydrophilic compounds were subjected to partial least-squares discriminant analyses (PLS-DA) to assess significant differences in the metabolites of L. radiata flowers from stages 1 to 4. Therefore, this study will serve as the foundation for a biochemical approach to understand both primary and secondary metabolism in L. radiata flower development.