Flavonoid Metabolism Research Articles

Selenium improves the flavor-promoting substances of summer tea (Camellia sinensis) by altering the expression of flavonoid and amino acids metabolic genes

Summer tea (Camellia sinensis) is less favored due to its inferior taste compared to spring tea. The application of selenium (Se) has proven effective in enhancing tea flavor. However, the specific mechanisms underlying the Se-mediated improvement of summer tea quality remain unclear. This study examines the alteration of trace elements, the metabolome, and the transcriptome in tea plants subjected to Se treatment. Se application increased the concentrations of B, Fe, Zn, and Se in the summer tea shoots of certain cultivars. Metabolomic analysis revealed that exogenous Se elevated the levels of theanine and flavonoids while reducing the catechin bitterness taste index in most of the selected cultivars. Transcriptomic analysis further demonstrated that Se treatment modulated the expression of CsSULTRs, CsPHTs, CsIRTs, CsZIPs, and CsBOTs, indicating a potential link between the accumulation of these elements and the corresponding transporter genes. Based on qRT-PCR results, CsSULTR1.1, 1.2, and 4.1 are likely involved in Se transport. Additionally, differentially expressed genes (DEGs) were predominantly enriched in the flavonoid and amino acid biosynthesis pathways following Se treatment. In conclusion, the addition of Se enhances the flavor profile of summer tea by modulating genes participating in flavonoid and amino acid metabolism, underpinning its potential for improving summer tea quality.

Flavonoids and anthocyanins in seagrasses: implications for climate change adaptation and resilience

Seagrasses are a paraphyletic group of marine angiosperms and retain certain adaptations from the ancestors of all embryophytes in the transition to terrestrial environments. Among these adaptations is the production of flavonoids, versatile phenylpropanoid secondary metabolites that participate in a variety of stress responses. Certain features, such as catalytic promiscuity and metabolon interactions, allow flavonoid metabolism to expand to produce novel compounds and respond to a variety of stimuli. As marine environments expose seagrasses to a unique set of stresses, these plants display interesting flavonoid profiles, the functions of which are often not completely clear. Flavonoids will likely prove to be effective and versatile agents in combating the new host of stress conditions introduced to marine environments by anthropogenic climate change, which affects marine environments differently from terrestrial ones. These new stresses include increased sulfate levels, changes in salt concentration, changes in herbivore distributions, and ocean acidification, which all involve flavonoids as stress response mechanisms, though the role of flavonoids in combatting these climate change stresses is seldom discussed directly in the literature. Flavonoids can also be used to assess the health of seagrass meadows through an interplay between flavonoid and simple phenolic levels, which may prove to be useful in monitoring the response of seagrasses to climate change. Studies focusing on the genetics of flavonoid metabolism are limited for this group, but the large chalcone synthase gene families in some species may provide an interesting topic of research. Anthocyanins are typically studied separately from other flavonoids. The phenomenon of reddening in certain seagrass species typically focuses on the importance of anthocyanins as a UV-screening mechanism, while the role of anthocyanins in cold stress is discussed less often. Both of these stress response functions would be useful for adaptation to climate change-induced deviations in tidal patterns and emersion. However, ocean warming will likely lead to a decrease in anthocyanin content, which may impact the performance of intertidal seagrasses. This review highlights the importance of flavonoids in angiosperm stress response and adaptation, examines research on flavonoids in seagrasses, and hypothesizes on the importance of flavonoids in these organisms under climate change.

Loss of flavonoids homeostasis leads to pistillody in sua-CMS of Nicotiana tabacum

The homeotic transformation of stamens into pistil-like structures (pistillody) causes cytoplasmic male sterility (CMS). This phenomenon is widely present in plants, and might be induced by intracellular communication (mitochondrial retrograde signaling), but its systemic regulating mechanism is still unclear. In this study, morphological observation showed that the stamens transformed into pistil-like structures, leading to flat and dehiscent pistils, and fruit set decrease in sua-CMS (MS K326, somatic fusion between Nicotiana. tabacum L. K326 and Nicotiana suaveolens). Transcriptome data analysis presented that the expression levels of B-class MADS genes, including pMADS1, GLO1, GLO2, pMADS2.1, pMADS2.2, significantly reduced in the pistil-like structure of sua-CMS. DEGs were enriched in flavonoid and phenylpropanoid biosynthesis pathways. Transcriptome and metabolomics analysis revealed that the expression levels of CHI/CHS (key enzymes regulating flavonoid synthesis), and the contents of flavonoids reduced significantly in the pistil-like structures of sua-CMS. Chemical fluorescence staining assay showed that reactive oxygen species (ROS) levels were higher in the pistil-like structure of sua-CMS. Application of external flavonoids (hesperetin) reduced the frequency of pistillody and ROS levels. These results suggested that the metabolism of flavonoids played important roles in regulating pistillody through ROS in sua-CMS. Our study provides new insights into the regulatory mechanism of pistillody in plants.

Integrated Metabolome, Transcriptome, and Physiological Analysis of the Flavonoid and Phenylethanol Glycosides Accumulation in Wild Phlomoides rotata Roots from Different Habitats.

Phlomoides rotata, a traditional medicinal plant, is commonly found on the Tibetan Plateau at altitudes of 3100-5200 m. Its primary active medicinal compounds, flavonoids and phenylethanol glycosides (PhGs), exhibit various pharmacological effects, including hemostatic, anti-inflammatory, antitumor, immunomodulatory, and antioxidant activities. This study analyzed flavonoid and PhG metabolites in the roots of P. rotata collected from Henan County (HN), Guoluo County (GL), Yushu County (YS), and Chengduo County (CD) in Qinghai Province. A total of differentially abundant metabolites (DAMs) including 38 flavonoids and 21 PhGs were identified. Six genes (UFGT1, CHS1, COMT2, C4H3, C4H8, and C4H5) and four enzymes (4CL, C4H, PPO, and ALDH) were found to play key roles in regulating flavonoid and PhG biosynthesis in P. rotata roots. With increasing altitude, the relative content of 15 metabolites, the expression of seven genes, and the activity of four enzymes associated with flavonoid and PhG metabolism increased. These findings enhance our understanding of the regulatory mechanisms of flavonoid and PhG metabolism in P. rotata and provide insights into the potential pharmaceutical applications of its bioactive compounds.

Combined transcriptomic and metabolomic analyses reveal the pharmacognostic mechanism of the metabolism of flavonoids in different parts of Polygonum capitatum.

The plant Polygonum capitatum (P. capitatum) contains a variety of flavonoids that are distributed differently among different parts. Nevertheless, differentially expressed genes (DEGs) associated with this heterogeneous distribution have not been identified. In this study, combined with transcriptomic and metabonomic analysis, we identified significant DEGs related to variations in flavonoid composition among different parts of P. capitatum. Subsequently, transcriptomic and nontargeted metabolomic analyses revealed that flavonoids and phenolic acids in different parts of P. capitatum were significantly enriched in the phenylpropanoid biosynthesis, shikimic acid biosynthesis, and flavonoid biosynthesis pathways. The expression levels of genes encoding enzymes, including shikimate O-hydroxycinnamoyltransferase (HCT), chalcone synthase (CHS), flavonoid 3',5'-hydroxylase (CYP75A), flavones 3-hydroxylase (F3H), flavonol synthase (FLS), leucoanthocyanidin reductase (LAR), trans-cinnamate 4-monooxygenase (CYP73A), and shikimate kinase (SK), were found to be the lowest in the leaves of P. capitatum via quantitative PCR. Interestingly, these genes are involved in the biosynthesis of quality markers such as gallic acid, quercetin, and quercitrin in P. capitatum. Finally, the targeted metabolomic results reconfirmed that the gallic acid, quercetin, and quercitrin contents were the highest in the leaves of P. capitatum. This research provides a theoretical basis for further understanding the differential regulatory mechanism of flavonoid metabolism in different parts of P. capitatum, providing novel insights into the pharmacognostic basis of P. capitatum.

Rice glycosyltransferase OsDUGT1 is involved in heat stress tolerance by glycosylating flavonoids and regulating flavonoid metabolism.

One significant environmental element influencing the growth and yield of rice (Oryza sativa L.) is high temperature. Nevertheless, the mechanism by which rice responds to high temperature is not fully understood. A rice glycosyltransferase gene, OsDUGT1, was identified as a heat-responsive gene in this investigation. Its function was studied by overexpression and knockout methods. The results showed that under heat stress, OsDUGT1 overexpression lines (OsDUGT1-OE) increased the survival rate of rice, while Osdugt1 knockout lines (Osdugt1-ko) decreased the survival rate compared to wild type (ZH11). In addition to rice, heat stress tolerance was also improved by ectopic expression of OsDUGT1 in transgenic Arabidopsis thaliana plants. We observed that ROS scavenging ability, malondialdehyde accumulation, and the ion leakage are relevant to the expression level of OsDUGT1. Through enzyme activity analysis, we found that OsDUGT1 could glycosylate flavonoid compounds. Correspondingly, the loss of OsDUGT1 function caused a significant decrease in endogenous flavonoid accumulation in rice, which was demonstrated by our metabolomics analysis. Additionally, our transcriptomic analysis of Osdugt1 mutant lines under heat stress condition indicated that mutation of OsDUGT1 can reduce the transcriptional activity of heat response related genes, antioxidant enzyme genes and other genes involved in the flavonoid biosynthetic pathway. In summary, our work revealed that OsDUGT1 plays a crucial role in adjusting and balancing the overall plant metabolism and transcription under heat stress through glycosylation of flavonoids, and offers a key prospect gene for breeding efforts to enhance crop heat tolerance under the trend of climate warming all over the globe.

Gut microbes modulate the effects of the flavonoid quercetin on atherosclerosis

Gut bacterial metabolism of dietary flavonoids results in the production of a variety of phenolic acids, whose contributions to health remain poorly understood. Here, we show that supplementation with the commonly consumed flavonoid quercetin impacted gut microbiome composition and resulted in a significant reduction in atherosclerosis burden in conventionally raised (ConvR) Apolipoprotein E (ApoE) knockout (KO) mice but not in germ-free (GF) ApoE KO mice. Metabolomic analysis revealed that consumption of quercetin significantly increased plasma levels of benzoylglutamic acid, 3,4 dihydroxybenzoic acid (3,4-DHBA) and its sulfate-conjugated form in ConvR mice, but not in GF mice supplemented with the flavonoid. Levels of these metabolites were negatively associated with atherosclerosis burden. Furthermore, we show that 3,4-DHBA prevented lipopolysaccharide (LPS)-induced decrease in transendothelial electrical resistance (TEER). These results suggest that the effects of quercetin on atherosclerosis are influenced by gut microbes and are potentially mediated by bacterial metabolites derived from the flavonoid.

Combination transcriptomic and metabolomic reveal deterioration of the blue honeysuckle (Lonicera caerulea L.) fruit and candidate genes regulating metabolism in the post-harvest stage

Blue honeysuckle, a new berry with high nutritional value, possesses typical berry postharvest properties, including extreme perishability, rapid quality loss, and high sensitivity to microbial infections. At present, the underlying mechanisms of postharvest quality deterioration, senescence, and low-temperature regulation remain largely unknown. This study aimed to elucidate the metabolic shifts and genetic regulation underlying the preservation or deterioration of blue honeysuckle during storage at room temperature (25 °C) and low temperature (4 °C). Storage at 4 °C inhibited fruit decay and preserved better visual quality, weight, firmness, and total soluble solid and acid contents. We identified 24 key differentially accumulated metabolites that specifically changed during the qualitative shift at room temperature and were effectively regulated by 4 °C. Commonly associated metabolites, sorbitol, succinic acid, malic acid, naringenin, pinobanksin, and taxifolin, characterize the deterioration of blue honeysuckle. These metabolites were integrated with transcriptomic data for weighted correlation network analysis (WGCNA). Regulatory networks were used for the identification of key genes and transcription factors (TFs) influencing sugar, organic acid, flavonoid, and phenolic acid metabolism during storage. The findings provide insight into metabolic regulation and the improvement of flavor in postharvest blue honeysuckle fruit.

Bixa orellana (Bixaceae) seeds as a potential source of bioactive compounds for modulating postprandial hyperglycemia.

α-Amylase (α-AMY) and α-glucosidase (α-GLU) inhibitors are important for controlling postprandial hyperglycemia (PHG). Bixa orellana (annatto) reported inhibitory activity against these enzymes because of its bioactive compound content. However, an understanding of its inhibitory mechanisms and metabolic profile is necessary to establish its therapeutic potential. The present study aimed to elucidate the inhibitory mechanisms of B. orellana extract (BOE) on α-AMY and α-GLU, identify and quantify its bioactive compounds using metabolomics (untargeted and targeted) analyses, and evaluate their interactions through in silico approaches. BOE exhibited IC50 values of 37.75 and 47.06 mg mL-1 for α-AMY and α-GLU, respectively, indicating mixed and competitive inhibition types. Thirty-six putative compounds were identified by untargeted metabolomics, mainly fatty acids (dethiobiotin, occidentalol, palmitic acid, norbixin, among others). The most significant biosynthetic pathways included secondary metabolites (unclassified), unsaturated fatty acids, phenylpropanoids and flavonoid metabolism. Eighteen compounds were identified and quantified by the targeted analysis, such as l-phenylalanine, gallic acid, protocatechuic acid and naringenin. In silico studies highlighted xanthoangelol, norbixin, myricetin and 26-hydroxybrassinolide as key compounds with the highest binding affinities to enzyme active sites. BOE effectively inhibited α-AMY and α-GLU, with gallic acid, naringenin, xanthoangelol, norbixin and 26-hydroxybrassinolide identified as key bioactive contributors. These findings provide molecular evidence of the inhibitory mechanisms of BOE and support its potential for PHG management and diabetes control. © 2024 Society of Chemical Industry.

Integrative analyses of the transcriptome and metabolome reveal comprehensive mechanisms of monolignol biosynthesis in response to bioclimatic factors in Magnolia officinalis

BackgroundMagnolia officinalis (M. officinalis) thrives in temperate, elevated regions, and its desiccated bark comprises medicinal monolignol. Both abiotic and biotic factors can influence the pharmacodynamic compounds of M. officinalis, which display a variety of capabilities. It was the goal of this study to find the main bioclimatic factors that impact the amount of helpful compounds in M. officinalis and to show how these bioclimatic factors influence the metabolic pathways of magnolol and honokiol through actions on transcripts and molecules. We assessed the amounts of medicinal compounds in M. officinalis from Baoxing (BX), Nanjiang (NJ), Xuanhan (XH), and Beichuan (BC) in Sichuan Province. After that, the bioclimatic factors were gathered and put together that affected the growth and used the transcriptome and metabolome to label the M. officinalis data. The associated metabolic pathways were analyzed based on significant alterations in bioclimatic factors.ResultsTemperature and precipitation influence the accumulation of bioactive compounds in M. officinalis, as well as the metabolism of monolignol, amino acids, flavonoids, α-linolenic acid, and arachidonic acids. Moreover, temperature was negatively related to the mounts of phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase (4CL), and cinnamoyl-CoA reductase (CCR) in the monolignol biosynthetic pathway, as well as to the amounts of cinnamyl alcohol and 4-coumaryl alcohol that were made.ConclusionsModerate temperatures and appropriate precipitation enhanced the metabolism of monolignols in M. officinalis, ascribed to elevated levels of effective enzyme that correlated with the temperature and precipitation modulation of PAL, 4CL, and CCR activity. Furthermore, this study discovered that cinnamonyl alcohol and 4-coumaryl alcohol were critical precursors for the production of magnolol and honokiol, indicating potential strategies for improving M. officinalis' pharmacodynamic characteristics.

SlNAC12, a novel NAC-type transcription factor, confers salt stress tolerance in tomato.

SlNAC12 enhances salt stress tolerance of transgenic tomato by regulating ion homeostasis, antioxidant activity and flavonoids biosynthesis Soil salinization is a major environmental factor that adversely affects plant growth and development. NAC (NAM, ATAF1/2, and CUC2) is a large family of plant-specific transcription factors that play crucial roles in stress response. Here, we investigated the role of a novel NAC transcription factor, SlNAC12, in conferring salt stress tolerance in tomato (Solanum lycopersicum). Subcellular localization and yeast assays studies revealed that SlNAC12 is localized in the nucleus with weak transcriptional activity. SlNAC12 transcript was induced by salt stress in the leaves and roots of tomato seedlings. Overexpression of SlNAC12 in tomato led to significantly reduced plant height and root length. Transgenic tomato lines overexpressing of SlNAC12 (OE#1 and OE#3) exhibited enhanced tolerance to salinity, as evidenced by reduced the inhibitory effect of growth parameters under salt stress compared to wild type (WT). Overexpression of SlNAC12 in tomato affected Na+ and K+ homeostasis, leading to reduced Na+/K+ ratio, enhanced activity of antioxidant enzymes and decreased reactive oxygen species (ROS) accumulation under salt stress. Furthermore, the transcript levels of several genes involved in flavonoids metabolism and the levels of flavonoids accumulation were increased in SlNAC12-overexpressing tomato lines. Collectively, this study suggests that SlNAC12 transcription factor enhances salt stress tolerance in tomato is correlated with ion homeostasis, antioxidant enzyme systems, and flavonoids accumulation.

Proteomic Insights into the Regulatory Mechanisms of the Freezing Response in the Alpine Subnivale Plant Chorispora bungeana.

Freezing temperatures impose significant constraints on plant growth and productivity. While cold tolerance mechanisms have been extensively studied in model species, the molecular basis of freezing tolerance in naturally adapted plants remains underexplored. Chorispora bungeana, an alpine plant with a strong freezing tolerance, provides a valuable model for investigating these adaptive mechanisms. In this study, we used Tandem Mass Tag (TMT)-based quantitative proteomics to analyze C. bungeana seedlings subjected to freezing stress (-6 °C) at 6 and 30 h, identifying 302 differentially expressed proteins (DEPs) compared with controls. Our findings capture the dynamic proteomic landscape of C. bungeana under freezing stress, revealing distinct early and prolonged responses. Early responses featured upregulated proteins involved in signaling and stress protection, with no clear involvement of the ICE1-CBF pathway (ICE1: Inducer of CBF Expression 1; CBF: C-repeat Binding Factor) found in cold-acclimating plants, while calcium signaling and epigenetic modifications enabled a rapid response. Extended exposure involved DEPs in RNA modification, glutamine metabolism, and biosynthesis of polysaccharides and flavonoids, highlighting metabolic adjustments crucial for long-term adaptation. By combining protein-protein interaction (PPI) networks and functional analysis, we identified 54 key proteins validated by qRT-PCR. These findings provide comprehensive insight into freezing tolerance mechanisms, identifying candidate proteins for enhancing cold resilience in crops and mitigating agricultural cold stress impacts.

Rare Earth Elements Induce Drought Tolerance in Dicranopteris pedata from Ion-Adsorbed Rare Earth Mining Area in Southern China

The ion adsorption rare earth (IARE) mining areas in southern China frequently experience severe seasonal drought, posing significant challenges to plant growth. This study investigates the hypothesis that rare earth elements (REEs) present in these mining areas induce drought resistance in Dicranopteris pedata (D. pedata). An experiment was designed with three drought stress intensities (0%, 5%, and 10% PEG6000) and three levels of rare earth element (REE) addition (none, low, and high). After 72 h of drought stress, physiological indices and metabolomic profiles of D. pedata were examined. The results showed that under drought conditions, the REE additions increased the catalase and peroxidase activities of D. pedata by 99.04% and 81.25%, respectively, and the contents of proline, soluble proteins, and soluble sugars by 97.52%, 71.24%, and 61.81%, respectively. Metabolomic analysis revealed up-regulation of lipid and lipid-like molecules, as well as flavonoid metabolism, which contribute to improved drought resistance in D. pedata under stress. Furthermore, REE addition further up-regulated flavonoid and anthocyanin synthesis compared to drought stress alone, enhancing the plant’s resilience to drought. These findings suggest that D. pedata responds to drought stress by modulating enzyme activities, osmoregulatory substances, and metabolic pathways upon REE exposure. This study underscores the dual role of REEs in enhancing both the drought tolerance and enrichment capacity of D. pedata in IARE mining areas, which is crucial for sustaining plant growth amidst drought stress, and provides new ideas for the ecological restoration and sustainable development of IARE mining areas.

Tissue-specific transcriptome analyses unveils candidate genes for flavonoid biosynthesis, regulation and transport in the medicinal plant Ilex asprella

It is not clear that the genes involved with flavonoids synthesis, regulation and transport in Ilex asprella. Transcriptome analysis of leaf, stem and root has uncovered 28,478 differentially expressed genes (DEGs) that are involved in various biological processes. Among these, the expression of 31 candidate synthetase genes, 19 transcription factors, and 5 transporters associated with flavonoid biosynthesis varies across tissues, encompassing seven complete biosynthetic pathways (stilbene, aurone, flavone, isoflavone, flavonol, phlobaphene, and anthocyanin) and one partial pathway (proanthocyanidin). Tissue-specific expression patterns suggest that the stilbenes, aurones, flavones and anthocyanin branches are more prominent in roots, as indicated by key genes such as STS(Ilex_044726), CH4ʹGT(Ilex_047989), FNS(Ilex_043640) and UFGT(Ilex_014720). In leaves, the phlobaphenes and flavonols branches are dominant, determined by CHI(Ilex_005941), FNR(Ilex_039777) and FLS(Ilex_046424). The isoflavone pathway appears to be more active in stems due to the presence of IFS(Ilex_029360), mirroring the accumulation of the intermediate metabolite chalcone, which is regulated by CHS(Ilex_047537). The absence of LAR genes implies that gallocatechin, and catechin liked proanthocyanidins cannot be synthesized in I. asprella. Meanwhile, the general phenylpropanoid pathway is more active in roots, stems than in leaves, as evidenced by the expression of PAL(Ilex_042231, Ilex_014816), C4H(Ilex_017598), and 4CL(Ilex_042033). Flavanone, dihydroflavonol and leucoanthocyanidin, key intermediates, accumulate more rapidly in stem, stem and root, respectively, regulated by CHI(Ilex_005941), F3H(Ilex_004635) and DFR(Ilex_004771). Correlation and network analyses reveal that candidate regulators and transporters are closely associated with the synthesis genes. The study provides profound snoop into flavonoids metabolism in I. asprella and offers valuable refer for medicinal plant.

Hydroxylase-oriented mining and functional characterization of camptothecin 10-hydroxylase from Camptotheca acuminata Decne

The regiospecific C-10 hydroxylation of camptothecin (CPT) is challenging from a chemical perspective. This step bridges the natural-sourced CPT to an important industrial material, 10-hydroxycamptothecin (10HCPT). 10HCPT is naturally generated in a medicinal plant, Camptotheca acuminata Decne. Functionally active hydroxylase responsible for regiospecific C-10 hydroxylation of CPT is undoubtedly existed in this plant. Therefore, the multi-omics database of C. acuminata was utilized to perform hydroxylase-oriented mining and screening. Three CYP81 genes were identified and two of them, including CYP81BQ18 and CYP81B256 catalyzed hydroxylation of CPT at the C-10 position. CYP81B256 and CYP81BN24 displayed quercetin C-5’ hydroxylase activity. CYP81B256 exhibited better catalytic performance for CPT than CYP81BQ18 and CPT10H in vitro. Furthermore, CYP81BQ18 and CYP81B256 displayed CPT 10-hydroxylase activity in tobacco. Functional verification in planta suggested that the newly observed CYP81BQ18 and CYP81B256 were involved in 10HCPT biosynthesis in C. acuminata. Subcellular localization analysis revealed that these CYP81 genes were located on the endoplasmic reticulum. Evolutionary analysis indicated that CYP81B256 and CYP81BN24 probably evolved from a same ancestral gene via gene duplication, while CYP81BQ18 evolved independently and acted as a specie-specific hydroxylase. CYP81B256 acted as an evolutionary intermediate gene bridging the alkaloid and flavonoid metabolism in C. acuminata. This research provides valuable insights into the function and evolutionary origin of CYP81s in the regiospecific hydroxylation step for 10HCPT biosynthesis.

A freezing responsive UDP-glycosyltransferase improves potato freezing tolerance via modifying flavonoid metabolism

A freezing responsive UDP-glycosyltransferase improves potato freezing tolerance via modifying flavonoid metabolism

Physiology and Metabolism Alterations in Flavonoid Accumulation During Buckwheat (Fagopyrum esculentum Moench.) Sprouting.

In this research, we investigated the physiological modifications, flavonoid metabolism, and antioxidant systems of two buckwheat (Fagopyrum esculentum Moench.) cultivars, Pintian and Suqiao, during germination. The results demonstrated an initial increase followed by a subsequent decline in the flavonoid content of the buckwheat sprouts throughout germination. On the third day of germination, the highest flavonoid concentrations were observed, with the Pintian and Suqiao varieties reaching 996.75 and 833.98 μg/g fresh weight, respectively. Both the activity and relative gene expression level of the flavonoid metabolizing enzyme showed a significant rise in 3-day-old buckwheat sprouts, which was strongly correlated with the flavonoid content. The correlation analysis revealed that the buckwheat sprouts accumulated flavonoids by enhancing the activities and gene expression levels of flavonoid synthases. The antioxidant capacity and the activities and gene expression profiles of the antioxidant enzymes in both buckwheat cultivars notably increased after three days of germination. The correlation analysis indicated a significant positive link between antioxidant capacity and the activity and gene expression levels of the antioxidant enzymes, flavonoid content, and total phenol content. This research demonstrated that germination treatment can significantly boost the accumulation of flavonoids and total phenols, thereby enhancing the antioxidant properties of buckwheat sprouts, despite variations among different buckwheat varieties.

Integrated Transcriptomic and Metabolomic Analysis Reveals Possible Molecular Mechanisms of Leaf Growth and Development in Disanthus cercidifolius var. longipes.

Background:Disanthus cercidifolius var. longipes is an ancient relic plant unique to China. However, the typical shade-loving plant is largely exposed to the sun, which poses a major challenge to its conservation. Methods: This study explored dynamic changes in primary and secondary metabolites in D. cercidifolius leaves at different stages of development, combining metabolomics and transcriptome analysis to discuss the differentially accumulated metabolites (DAMs) and differentially expressed genes (DEGs). Results: The DAMs and DEGs were enriched in pathways related to photosynthesis, carbon (C) metabolism, anthocyanin synthesis, plant hormone signal transduction, and flavonoid synthesis. At the initial stage of leaf development, many primary metabolites were synthesized in the leaves. Before leaf maturity, many primary metabolites were converted into secondary metabolites. Combined transcriptome and metabolome analysis showed that the metabolites and genes related to anthocyanin synthesis and flavonoid metabolism were upregulated. In contrast, the genes related to C metabolism and C fixation were downregulated. After leaf maturity, photosynthetic capacity increased, total flavonoid content peaked (implying the strongest photoprotection capacity), and the transformation of anthocyanins and flavonoids was weakened. Conclusions: Light intensity indirectly affects the accumulation of the primary and secondary metabolism of D. cercidifolius. With the enhancement of photoprotection, the photosynthetic energy capacity decreases. It is, therefore, inferable that D. cercidifolius has shading properties and achieves a stable nutrient supply during growth and development through these strategies. Thus, D. cercidifolius protection requires a shaded environment.

Metabolomic changes in Citrus reticulata peel after conventional and ultrasound-assisted solid-state fermentation with Aspergillus niger: A focus on flavonoid metabolism

This study explored the changes in nutrients, metabolites, and enzyme activity in Citrus reticulata peel powders (CRPP) under conventional or ultrasound-assisted solid-state fermentation (SSF) using Aspergillus niger CGMCC 3.6189. Compared to nonfermented CRPP (NF-CRPP), ultrasound-assisted fermented CRPP (UIS-CRPP) significantly increased total protein and carotenoid levels by 85.26 % and 179.68 %, respectively, surpassing conventionally-fermented CRPP (FO-CRPP). Among the 521 identified differential metabolites, organic acids, lipids, and flavonoids were predominant. Flavonoid accumulation was primarily driven by the flavone and flavonol biosynthesis pathway, with 90.47 % and 90.00 % of differential flavonoids upregulated in FO-CRPP and UIS-CRPP, respectively. SSF significantly increased phenylalanine, tyrosine, and methionine levels, and tyrosine ammonia-lyase and β-D-glucosidase activities, with higher levels in UIS-CRPP. These findings suggest that conventional and ultrasound-assisted fermentation enhances flavonoid levels in CRPP by modulating key enzyme activities in flavonoid biosynthesis and biotransformation. Our study offers a feasible approach for producing value-added products from citrus peel waste.

Transcriptome sequencing and SSR prediction of Clematis calyx based on SMRT sequencing platform

Clematis is an excellent vertical greening plant for garden viewing vines, with great ornamental and high medicinal value. To obtain transcriptome information and functional gene data for the Clematis calyx, this study utilized three biological replicates of the calyx from each of the three Clematis varieties: ‘Henryi’, ‘Polish spirit’, and ‘Mme Julia Correvon’ Single-molecule real-time sequencing technology was employed for full-length transcriptome sequencing. The study revealed that 21,673,173 non-chimeric sequences were identified through full-length transcriptome sequencing. After clustering, correction, and redundancy removal, 40,465 high-quality, full-length transcripts were obtained. Among these transcripts, there were 15,488 long non-coding RNA (lncRNA), 9,212 simple sequence repeats (SSR) sites, 1,247 transcription factors (TFs), 1,228 alternative splicing events, and 7,189 selectively polyadenylation sites predicted. In addition, 7,442 primer pairs were designed based on the SSR sites, covering 80.76% of the total SSR. 15 primer pairs were randomly selected for amplification, and 73.3% of them were successfully amplified. Transcript annotation results showed that 38,439, 38,094, 26,815, and 33,407 transcripts were annotated to the Nr, KEGG, KOG, and SwissProt databases, respectively. Among these, the KEGG database identified 137 metabolic pathways, including biosynthesis of secondary metabolites, carbon metabolism, and amino acid biosynthesis. 104 and 7 transcripts are involved in the flavonoid and anthocyanin metabolism pathways, respectively. The above results provide initial insights into the transcriptome information and functional characteristics of Clematis calyx. This critical data supports future research on marker primers for the color mechanism of Clematis calyx, the pathways and regulatory mechanisms of flavonoids and other products, as well as specific trait genes.