Search Results (106)

Finger millet (Eleusine coracana L.) is rich in bioactive compounds, including flavonoids. Following exogenous substance regulation, its sprouts can achieve efficient flavonoid enrichment. This study investigates the regulatory effects of exogenous salicylic acid (SA) and γ-aminobutyric acid (GABA) on the physiological metabolism, oxidative stress response, and flavonoid biosynthesis of finger millet sprouts subjected to 5 mM zinc sulfate (ZnSO₄) stress. Compared to treatment solely with ZnSO₄, the application of both 50 μM salicylic acid (SA) and 1 mM gamma-aminobutyric acid (GABA) markedly enhanced flavonoid biosynthesis, with respective yields of 8.53 μg/sprout and 8.85 μg/sprout observed by 6 days post-germination. Concurrently, SA and GABA attenuated ZnSO₄-induced oxidative damage. During days 4 and 6 post-germination, malondialdehyde and hydrogen peroxide levels in sprouts were significantly reduced, with levels at 6 days showing a particularly notable decrease. Moreover, the catalytic activities of catalase, peroxidase, superoxide dismutase, and ascorbate peroxidase were significantly upregulated. Further analysis revealed that both treatments significantly activated the phenylpropanoid biosynthesis pathway. The activities of key rate-limiting enzymes, phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, and 4-coumarate-CoA ligase, along with the expression levels of their corresponding genes, were markedly upregulated. Concurrently, the expression of genes and transcription factors, specifically myeloblastosis and NAC transcription factors, involved in regulating reactive oxygen species homeostasis also increased. These findings suggest that exogenous SA, GABA, and ZnSO₄ cotreatment can effectively enhance the accumulation of flavonoids and the nutritional quality of finger millet sprouts by bolstering antioxidant capacity and modulating the flavonoid biosynthesis pathway. This investigation establishes a theoretical framework for the production of superior, bioactive finger millet sprout ingredients. Full article

Spatholobus suberectus is a traditional edible, ornamental, and medicinal vine with an abundant flavonoid content in its dried stems. An integrated metabolomic and transcriptomic analysis was conducted on its vegetative organs to identify flavonoid biosynthesis pathways. The results showed that: (1) a total of 268 flavonoids could be identified among all the vegetative organs, and stems accumulated most of them; (2) a total of 449,569,220 clean reads were retained from all the vegetative organs (many genes related to key enzymes of flavonoid biosynthesis and transcription factors were found in all the compared groups between different organs; among them, 77 genes showed high correlations with key flavonoids in different pathways); and (3) PAL (encoding phenylalanine ammonia-lyase), 4CL (encoding 4-coumarate: CoA ligase), C4H (encoding cinnamate-4-hydroxylase), CHS (encoding chalcone synthase), DFR (encoding dihydroflavonol 4-reductase) and others showed positive correlations with L-phenylalanine and various flavonoids, while FLS (encoding flavonol synthase) showed negative correlations with many flavonols and flavonoids, as revealed through integrated analysis. This study reveals the flavonoid biosynthesis characteristics in S. suberectus and provides new insights into the utilization of its biological resources. Full article

Exposure to abiotic stresses commonly stimulates the production of secondary metabolites in plants, and flavonoids represent a major class of these bioactive compounds. NaCl effects on antioxidant system treatment and flavonoid production in buckwheat sprouts was examined in this study using buckwheat as the raw material. In order to clarify the regulatory function of NaCl in these physiological processes, the changes in pertinent indices of buckwheat sprouts exposed to the control and NaCl treatments were studied. The results indicated that at three days old, the sprouts subjected to 80 mM NaCl treatment exhibited the highest total flavonoid content. The significant increase in enzyme activity (cinnamate 4-hydroxylase and 4-coumaroyl-CoA ligase, etc.) responsible for flavonoid biosynthesis provides strong evidence for this conclusion. The antioxidant system in buckwheat was activated by NaCl treatment, as evidenced by the dramatically increased antioxidant enzyme activities and the relative levels of expression of their respective genes compared to the control group. Levels of malondialdehyde and hydrogen peroxide were markedly higher than those in the control group, indicating that NaCl treatment inhibited the growth of buckwheat sprouts. This study not only reveals the mechanisms underlying buckwheat’s response to NaCl stress but also lays a theoretical foundation for developing functional foods enriched with flavonoid-rich buckwheat sprouts. Full article

Cibotium barometz (L.) J. Sm., a medicinally significant fern in traditional Chinese medicine, is little explored at the genomic level regarding its bioactive compounds. Using an integrated approach combining Illumina and PacBio sequencing technologies, we profiled its root, rachis, and pinna transcriptomes, identifying 12,718, 21,341, and 11,441 unigenes, respectively. Our analysis systematically characterized the transcriptional features of transcription factors (TFs), simple sequence repeats (SSRs), long non-coding RNAs (lncRNAs), and differentially expressed genes (DEGs). Enrichment analyses highlighted the roles of highly expressed unigenes in secondary metabolism. Seventeen key enzymes involved in polysaccharide biosynthesis showed tissue-specific expression patterns. Notably, total polysaccharide content correlated positively with UDP-arabinose 4-epimerase (UXE) expression but negatively with phosphoglucomutase (PGM) and 3,5-epimerase/4-reductase (UER1). Flavonoid accumulation inversely correlated with chalcone synthase (CHS) expression. Two lignin pathways (H-lignin and G-lignin) were characterized, with phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), and cinnamyl alcohol dehydrogenase (CAD) as key genes. The absence of ferulate-5-hydroxylase (F5H) explains the undetected S-lignin pathway. Regulatory network analysis revealed positive correlations between PAL expression and NAC72/NAC78/WRKY35 and C4H expression and WRKY65/WRKY69/WRKY71, while a negative correlation was revealed between flavonoid 3′,5′-hydroxylase (F3′5′H) and MYB3R4. This study provides comprehensive transcriptomic insights into C. barometz bioactive compound biosynthesis, serving as a foundation for mechanistic research. Full article

Fragrance lotus (Nymphaea hybrid) is a tropical interspecific cultivar characterized by large flowers and high scent intensity, offering dual potential for ornamental commerce and natural fragrance extraction. Floral scent determines both economic value and pollinator attraction, yet the biosynthetic organs and metabolic routes remain undocumented. To fill this gap, single flowers of the high-aroma cultivar ‘Eldorado’ at full anthesis were dissected into petal (PE), stamen (ST) and pistil (PI); each organ was subjected to untargeted LC-MS/MS metabolomics and Illumina RNA-seq. Organ-specific gene–metabolite co-expression networks were constructed by pairwise integration of transcript and metabolite matrices. All three organs formed distinct clusters in principal-component space. Compared with PE, 6221, 3352 and 5891 differentially expressed genes (DEGs) together with 30, 24 and 39 differentially accumulated metabolites (DAMs) were identified in ST, PI and PE, respectively. The phenylpropanoid biosynthesis pathway (map00940) was the only route simultaneously enriched at both transcript and metabolite levels; 59 DEGs mapped to this pathway co-linearly with three scent-related DAMs. ST contained the highest concentration of scent-active volatiles; phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL) and benzaldehyde reductase (BAR) were all significantly up-regulated in this organ, driving the accumulation of p-coumaric acid that is subsequently channeled into benzyl alcohol via side-chain cleavage and BAR-mediated reduction, thereby generating the characteristic fragrance of Nymphaea. This study provides the first organ-level resolution of scent biosynthesis and metabolic flux partitioning in fragrance lotus, furnishing molecular targets for directed aroma improvement and efficient natural fragrance extraction. Full article

Passion fruit deteriorates rapidly after harvest owing to fungal decay and quality loss. This study examined whether acidic electrolyzed water (AEW, pH 2.5) could strengthen host defense responses and thereby prolong the marketable storage period of passion fruit. Freshly harvested yellow passion fruits (without any prior storage) were immersed for 20 min in AEW containing 0 (control), 30, 60 or 90 mg/L available chlorine concentration (ACC) and then packaged in polyethylene film bags and stored at 25 °C for 15 days to simulate typical ambient handling/marketing conditions, where polyethylene packaging is commonly used to maintain a high-humidity microenvironment and reduce moisture loss; physicochemical attributes, decay parameters and disease-resistance-related enzyme activities were then monitored. AEW—particularly at 60 mg/L ACC—significantly lowered decay incidence, disease index and cell membrane permeability while preserving pericarp color (hue angle h, L*) and pulp titratable acidity, vitamin C, total soluble solids, and total soluble sugars. The same treatment elevated the concentrations of disease-resistant metabolites (total polyphenolics, flavonoids and lignin) and up-regulated the activities of peroxidase, cinnamate-4-hydroxylase, 4-coumarate CoA ligase, phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase, chitinase, and β-1,3-glucanase. These findings demonstrate that AEW mitigates postharvest deterioration of passion fruit by activating the metabolism of disease-resistant substances, highlighting its potential as an eco-friendly technology for maintaining quality during ambient handling/marketing conditions. Full article

Bamboo shoots represent a traditional food in China, with most varieties exhibiting a bitter taste; however, understanding of the compounds responsible for this bitterness remains limited. In this study, shoots of a special-germplasm bitter-tasting Dendrocalamus brandisii (Dbs) were investigated, using sweet-tasting Dendrocalamus brandisii (Db) shoots as a control. Electronic tongue analysis, broad-target metabolomics, targeted metabolomics, and transcriptomics were employed to identify the metabolites and key genes associated with bitterness in Dbs shoots. Electronic tongue measurements revealed a significant difference in bitterness between the two groups. Human sensory evaluation confirmed that Dbs was perceived as significantly more bitter and less sweet than Db (p < 0.01). Nontargeted metabolomics screening identified 43 differential metabolites, 19 of which were upregulated in Dbs. Targeted analysis of these differential metabolites, combined with the BitterDB database and previously reported bitter compounds, suggested that 4-Hydroxybenzoate, gallic acid, epicatechin, tryptophan, histidine, and apigenin may contribute to the bitterness of Dbs. Among these, 4-Hydroxybenzoate showed an approximately 92-fold higher content in Dbs compared to Db. The taste activity values (TAVs) of the identified bitter compounds were calculated; only 4-Hydroxybenzoate exhibited a TAV greater than 1 (14.581), while the TAV of the other compounds were all below 1. Integrating broad-target metabolomics, targeted metabolomics, and TAV analysis, 4-Hydroxybenzoate was inferred to be one of the primary bitter substances. Transcriptomic analysis indicated significant upregulation of key genes in the biosynthetic pathway of 4-Hydroxybenzoate, including PAL, 4CL, and C4H. Enzyme activity assays further demonstrated that phenylalanine ammonia-lyase, 4-coumarate-CoA ligase, and cinnamate 4-hydroxylase activities were markedly higher in Dbs than in Db. RT-qPCR validation confirmed that the expression levels of 4CL3, 4CL4, PAL1, PAL2, PAL3, PAL4, and PTAL were significantly elevated in Dbs, consistent with the transcriptomic data. In conclusion, 4-Hydroxybenzoate is proposed as the most likely key compound responsible for the bitterness in Dbs shoots. This study provides valuable insights into the bitterness formation mechanism in this Dbs and offers important information for the improvement of its edible quality. Full article

In this study, we aimed to elucidate the mechanism through which treatment with slight water loss combined with methyl jasmonate (MeJA) regulates gray mold development in Actinidia arguta, focusing on reactive oxygen species (ROS) and phenylpropanoid metabolism. The results showed that water loss alone, MeJA alone, and their combination each reduced the incidence of disease, with the combined treatment showing the greatest efficacy. At the end of the storage period, the combined treatment enhanced the activities of superoxide dismutase (SOD), polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumarate-CoA ligase (4CL). It also increased the accumulation of defense-related substances (total phenol and lignin contents) and up-regulated AaPAL, Aa4CL, AaC4H, and AaC3′H gene expression. Furthermore, the combined treatment reduced the disease severity index from 60% to 16% and delayed onset by 2 d. In conclusion, slight water loss combined with MeJA treatment effectively suppressed gray mold. This effect may be attributed to activation of ROS metabolism, induction of phenylpropanoid metabolism, and up-regulation of related genes, which enhanced the resistance of the fruit to gray mold. Full article

Objectives: Angelica sinensis is a type of traditional Chinese medicine (TCM) used primarily as a blood tonic. The chemical components that exert their efficacy are mainly bioactive metabolites, such as ferulic acid, flavonoids, and volatile oils. The resources of wild Angelica sinensis (WA) are very scarce, and almost all the market circulation of TCM formulations relies on cultivated Angelica sinensis (CA). Some studies have shown that WA and CA differ in morphological features and chemical composition, but the reasons and mechanisms behind the differences have not been studied deeply. Methods: Herein, metabolomics analysis (MA) and transcriptomics analysis (TA) were used to reveal the differences in bioactive metabolites and genes between WA and CA. Expression of key genes was verified by real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Results: Results showed that 12,580 differential metabolites (DMs) and 1837 differentially expressed genes (DEGs) were identified between WA and CA. Fourteen DMs (e.g., cinnamic acid, caffeic acid, ferulic acid, p-coumaroylquinic acid, and phlorizin) and 27 DEGs (e.g., cinnamic acid 4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), shikimate O-hydroxycinnamoyltransferase (HCT), caffeic acid-O-methyltransferase (COMT), cinnamyl-alcohol dehydrogenase (CAD), flavonol synthase (FLS)) were screened in phenylpropanoid biosynthesis and flavonoid biosynthesis. A combined analysis of MA and TA was performed, and a network map of DMs regulated by DEGs was plotted. The results of real-time RT-qPCR showed that the transcriptome data were reliable. Conclusions: These findings provide a reference for further optimization of the development of WA cultivation and breeding of CA varieties. Full article

Under light exposure, certain pepper cultivars synthesize large amounts of anthocyanins in their pericarps, with the illuminated areas exhibiting black coloration. However, research on light-induced anthocyanin formation in pepper fruit, particularly the related metabolites and genetic changes, remains limited. To identify the key genes involved in localized anthocyanin synthesis under light conditions, we investigated the black pericarps (light-exposed) and green pericarps of pepper variety MSCJ1 under illumination. Metabolomics analysis identified 579 metabolites in the black and green pepper pericarps, with 50 differentially accumulated metabolites. Petunidin-3-(6″-p-coumaroyl-glucoside) and delphinidin-3-p-coumaroyl-rutinoid accumulation represented the main factor underlying light-induced blackening of the pericarp. RNA-seq identified 121 differentially expressed genes that were significantly enriched in the flavonoid biosynthesis pathway. The genes for phenylalanine ammonia lyase (Capana09g002200, Capna09g002190), cinnamic acid hydroxylase (Capana06g000273), chalcone synthase (Capana05g002274), flavonoid 3-hydroxylase (Capana02g002586), flavonoid 3′-hydroxylase (MSTRG.15987), dihydroflavonol 4-reductase (Capana02g002763), anthocyanin synthase (Capana01g000365), UDP glucosyltransferase (Capana03g000135), and glutathione S-transferase (Capana02g002285) were key genes for anthocyanin synthesis and transport. Transcription factors bHLH (Capana09g001426, Capana09g001427), HSFB3 (Capana05g000086), and TCP4 (Capana07g002142) participated in the regulation of anthocyanin synthesis. These results broaden our understanding of the mechanism of light-induced anthocyanin synthesis in pepper peel. Full article

Verticillium wilt (VW), caused by Verticillium dahliae, poses a significant threat to global cotton production. Through analysis of public transcriptome databases, this study identified GhSTZ, a C2H2 zinc finger protein transcription factor gene, which was significantly induced by V. dahliae. Suppressing GhSTZ expression via virus-induced gene silencing significantly enhanced cotton resistance to VW. This resistance manifested as a 1.2-fold increase in lignin deposition, optimized ROS (reactive oxygen species) homeostasis, and a 1.3-fold elevation in glucose levels. Transcriptome analysis revealed 338 differentially expressed genes in GhSTZ-silenced plants, with 97 upregulated and 241 downregulated. Key downregulated genes included PME (pectin methylesterase) and PG1-pec (polygalacturonase) in the pentose phosphate pathway, while the key upregulated genes comprised C4H (cinnamate 4-hydroxylase) and C3H (p-coumarate 3-hydroxylase) in the phenylpropanoid biosynthesis pathway. Notably, in the plant–pathogen interaction signaling pathway, approximately half of the genes exhibited upregulated expression while the other half showed downregulation. Protein–protein interaction network analysis further revealed cooperative interaction between PME and the secoisolariciresinol dehydrogenase SIRD. This study is the first to elucidate GhSTZ as a negative regulator that compromises cotton disease resistance through a tripartite mechanism. These findings offer a novel approach to enhancing crop disease resistance by targeting the negative regulatory genes. Full article

Flavonoids serve as crucial plant antioxidants in drought tolerance, yet their antioxidant regulatory mechanisms within mycorrhizal plants remain unclear. In this study, using a two-factor design, trifoliate orange (Poncirus trifoliata (L.) Raf.) seedlings in the four-to-five-leaf stage were either inoculated with Funneliformis mosseae or not, and subjected to well-watered (70–75% of field maximum water-holding capacity) or drought stress (50–55% field maximum water-holding capacity) conditions for 10 weeks. Plant growth performance, photosynthetic physiology, leaf flavonoid content and their antioxidant capacity, reactive oxygen species levels, and activities and gene expression of key flavonoid biosynthesis enzymes were analyzed. Although drought stress significantly reduced root colonization and soil hyphal length, inoculation with F. mosseae consistently enhanced the biomass of leaves, stems, and roots, as well as root surface area and diameter, irrespective of soil moisture. Despite drought suppressing photosynthesis in mycorrhizal plants, F. mosseae substantially improved photosynthetic capacity (measured via gas exchange) and optimized photochemical efficiency (assessed by chlorophyll fluorescence) while reducing non-photochemical quenching (heat dissipation). Inoculation with F. mosseae elevated the total flavonoid content in leaves by 46.67% (well-watered) and 14.04% (drought), accompanied by significantly enhanced activities of key synthases such as phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), 4-coumarate:coA ligase (4CL), and cinnamate 4-hydroxylase (C4H), with increases ranging from 16.90 to 117.42% under drought. Quantitative real-time PCR revealed that both mycorrhization and drought upregulated the expression of PtPAL1, PtCHI, and Pt4CL genes, with soil moisture critically modulating mycorrhizal regulatory effects. In vitro assays showed that flavonoid extracts scavenged radicals at rates of 30.07–41.60% in hydroxyl radical (•OH), 71.89–78.06% in superoxide radical anion (O₂^•−), and 49.97–74.75% in 2,2-diphenyl-1-picrylhydrazyl (DPPH). Mycorrhizal symbiosis enhanced the antioxidant capacity of flavonoids, resulting in higher scavenging rates of •OH (19.07%), O₂^•− (5.00%), and DPPH (31.81%) under drought. Inoculated plants displayed reduced hydrogen peroxide (19.77%), O₂^•− (23.90%), and malondialdehyde (17.36%) levels. This study concludes that mycorrhizae promote the level of total flavonoids in trifoliate orange by accelerating the flavonoid biosynthesis pathway, hence reducing oxidative damage under drought. Full article

Finger millet (Eleusine coracana L.) is a nutrient-dense cereal with high flavonoid content, yet the mechanisms regulating its secondary metabolite biosynthesis remain underexplored. Various exogenous stimuli can readily activate the enzymatic pathways and gene expression associated with flavonoid biosynthesis in plants, which are regulated by developmental cues. Research has established that methyl jasmonate (MeJA) application enhances secondary metabolite production in plant systems. This investigation examined MeJA’s influence on flavonoid accumulation and physiological responses in finger millet sprouts to elucidate the molecular mechanisms underlying MeJA-mediated flavonoid accumulation. The findings revealed that MeJA treatment significantly suppressed sprout elongation while enhancing the biosynthesis of total flavonoids and phenolic compounds. MeJA treatment triggered oxidative stress responses, with hydrogen peroxide and superoxide anion concentrations increasing 1.84-fold and 1.70-fold compared to control levels at 4 days post-germination. Furthermore, the antioxidant defense mechanisms in finger millet were upregulated following treatment, resulting in significant enhancement of catalase and peroxidase enzymatic activities and corresponding transcript abundance. MeJA application augmented the activities of key phenylpropanoid pathway enzymes—phenylalanine ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H)—and upregulated their respective gene expression. At 4 days post-germination, EcPAL and EcC4H transcript levels were elevated 3.67-fold and 2.61-fold, respectively, compared to untreated controls. MeJA treatment significantly induced the expression of downstream structural genes and transcriptional regulators. This study provides a deeper understanding of the mechanism of flavonoid accumulation in foxtail millet induced by MeJA, and lays a foundation for exogenous conditions to promote flavonoid biosynthesis in plants. Full article

Colletotrichum capsici is an important pathogen causing anthracnose in postharvest peppers in parts of Asia, seriously compromising quality and storage life. Unveiling the pathogenic mechanism can better prevent postharvest disease in pepper. This study investigated the impacts of C. capsici infection on cell wall and phenylpropanoid metabolism in postharvest pepper. Compared to the non-inoculated peppers, C. capsici infection notably increased the disease index, damaged visual quality, and reduced the firmness. Morphological observations showed that C. capsici infection contributed to the collapse of epidermal cell structure. During the early stage, C. capsici triggered pepper’s defensive responses, including lignin deposition around the wounds, increased cellulose and hemicellulose content, and boosted disease-resistance enzymes, including phenylalanine ammonia-lyase (PAL), cinnamic acid 4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), cinnamyl alcohol dehydrogenase (CAD), laccase (LAC), β-1,3-glucanase (β-1,3-Glu), and chitinase (CHI), alongside elevated total phenolics and flavonoids. However, as storage time progressed, the activities of carboxymethy cellulase (Cx), polygalacturonase (PG), pectin methylesterase (PME), and β-glucosidase (β-Glu) remained at a high level, leading to a reduction in cell wall components, a decline in the activities of disease-resistance enzymes, and a decrease in phenylpropanoid metabolite, resulting from disease progression in pepper. These insights highlight the need for early intervention strategies to mitigate postharvest losses by targeting pathogen-induced stress responses and cell wall integrity preservation. Full article

The market value of litchi fruit is declining quickly due to its susceptibility to disease and rapid pericarp browning. Slightly acidic electrolyzed water (SAEW) treatment is recognized as a safe disinfection technology that not only preserves the quality of postharvest produce, but also enhances disease resistance. This study assessed the efficacy of SAEW in preserving litchi fruit and boosting its resistance to disease. Litchi fruit underwent treatment with SAEW at various available chlorine concentrations (ACC) (10, 25, 50, and 75 mg/L) and subsequently stored at 25 °C for a duration of six days. The results revealed that SAEW with an ACC of 25 mg/L markedly improved the postharvest quality of litchi fruits, reduced disease incidence, and enhanced the appearance of the pericarp and nutrient levels in the arils. Additionally, this treatment enhanced the levels of disease resistance-related compounds, including lignin, flavonoids, and total phenolics, in the pericarp of litchis during the later storage stages (p < 0.05). Furthermore, in the final three days of storage, there were also noticeable increases (p < 0.01) in the activities of pericarp disease resistance enzymes (DREs), such as phenylalanine ammonialyase, cinnamate-4-hydroxylase, 4-coumarate CoA ligase, cinnamyl alcohol dehydrogenase, peroxidase, polyphenol oxidase, chitinase, and β-1,3-glucanase. Based on these results, it was concluded that SAEW triggered DRE activities and increased the accumulation of disease resistance-related compounds by regulating the phenylpropane pathway to suppress disease development, and elevated the storage quality of harvested litchi fruit. Consequently, SAEW has proven to be an effective and safe method for enhancing the storability of litchi fruit. Full article