Search Results (139)

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

To explore the effects of various zinc (Zn) fertilizer application methods and concentrations on foxtail millet quality and flavonoid biosynthesis, we used Zhangzagu 13 as the experimental material. The transcriptome and metabolome were used to examine variations in flavonoid biosynthesis and metabolism in foxtail millet under different Zn application methods. The results showed that different Zn application methods significantly increased the total polyphenol, carotenoid, total flavonoid, and Zn contents in the grains of foxtail millet. Under the basal soil application (S3) and foliar spray (F2) treatments, the total flavonoid content significantly increased by 45.87% and 64.40%, respectively, compared with that of CK. Basal soil Zn fertilization increased the flavonoid content of foxtail millet by up-regulating genes related to flavonoid metabolism and biosynthesis, including flavanone-3-hydroxylase, chalcone isomerase, and leucoanthocyanidin reductase. Foliar Zn application enhanced flavonoid content by up-regulating genes involved in flavonoid metabolic and biosynthetic processes and chalcone isomerase. In conclusion, using Zn fertilizer can improve the synthesis and metabolism of foxtail millet flavonoids, effectively increase the content of functional substances in grains, and realize the biofortification of foxtail millet grains. 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

Peach is a typical ethylene-sensitive fruit, and low levels of ethylene can accelerate softening during storage. In this study, we used an ethylene absorbent (EA) and 1-methylcyclopropene (1-MCP) to minimize the detrimental impact of ethylene on the quality of peaches in modified atmosphere packaging (MAP), and analyzed fruit firmness, color change, anthocyanin content, and the expression patterns of cell wall metabolism-related genes and anthocyanin synthesis-related genes during storage. The results showed that ethylene in the MAP package decreased the firmness and total anthocyanin content of the peaches, while MAP combined with EA (MAP+EA) treatment effectively maintained the firmness of the peaches and counteracted the inhibition of anthocyanin accumulation in the peach skin by ethylene. In addition, the peaches treated with MAP+EA exhibited higher a* values, lower weight loss, and lower activities of cell-wall-modifying enzymes. Meanwhile, MAP+EA treatment also significantly increased the expression of color-related genes such as flavonoid 3′-hydroxylase gene (F3′H), dihydroflavonol 4-reductase (DFR), anthocyanidin synthase (ANS), and UDP-flavonoid 3-O-glucosyltransferase (UFGT). Furthermore, a good synergistic effect was observed between 1-MCP and EA in delaying softening and promoting coloring of peach fruit in the MAP package. The combination of 1-MCP and EA treatment may have the potential to alleviate softening and improve the color and quality of post-harvest fruit during storage. Full article

This study explores the metabolite diversity and potential medicinal value of three Paphiopedilum species—P. dianthum, P. micranthum, and P. barbigerum—using widely targeted metabolomics via HPLC-MS/MS in conjunction with in vitro antioxidant assays. A total of 2201 metabolites were detected across the three species, with flavonoids emerging as the dominant class (480 compounds, accounting for 21.8% of total metabolites). Comparative metabolomic analysis showed that flavonoid levels varied most prominently among the species. Notably, the metabolic profile of P. barbigerum (PB) diverged substantially from those of P. dianthum (PD) and P. micranthum (PM), which shared a higher degree of similarity with each other. Quantitative evaluation of antioxidant-associated metabolites revealed that PB exhibited the greatest enrichment in compounds with antioxidant potential, particularly flavonoids and phenolic acids, followed by PM and PD. These results were corroborated by antioxidant assays, in which PB demonstrated the highest free radical scavenging activity, with PM and PD displaying progressively lower effects. Differences in flavonoid content likely underpin these variations in antioxidant capacity. KEGG pathway enrichment analysis indicated that differentially expressed metabolites were primarily involved in flavonoid-associated biosynthetic routes, notably flavonoid biosynthesis (ko00941) and isoflavonoid biosynthesis (ko00943), with ko00941 being the most enriched. Within this pathway, PB showed eight significantly upregulated flavonoid metabolites, while PM and PD had seven and five, respectively. The observed differences may stem from species-specific expression of key biosynthetic enzymes such as flavonoid 3′-hydroxylase (F3′H) in PM and flavonoid 3′,5′-hydroxylase (F3′5′H) in PB, which influence both flavonoid composition and antioxidant potential. 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

Flavonoids play a crucial role in plant development, resistance, and the pigmentation of fruits and flowers. This study aimed to uncover the mechanism of flavonoid biosynthesis and fruit coloring in muscadine grapes. Two muscadine genotypes (Paulk and Supreme) were investigated via metabolomic and transcriptomic analysis during three developmental stages (bunch closure, veraison stage, and ripening stage). A total of 314 flavonoids were identified, with flavones and flavonols being the primary constituents. The contents of many differentially accumulated metabolites (DAMs) were higher at the veraison stage. The total anthocyanin content was upregulated during berry development, with the dominant type of anthocyanidin-3,5-O-diglucoside. Proanthocyanins accumulated higher levels in the ripening stage of Paulk than Supreme. Transcriptomic analyses revealed that over 46% of the DEGs exhibited higher expression levels in the bunch closure stage. Moreover, phenylalanine ammonia-lyase (PAL), cinnamyl 4-hydroxylase (C4H), and coumaryl CoA ligase (4CL) genes were upregulated during berry development, suggesting they promote second metabolites biosynthesis. The upregulation of dihydroflavonol 4-reductase (DFR) and leucoanthocyanin reductase (LAR) may related to the higher levels of PA in Paulk. Anthocyanidin synthase (ANS) and UDP-glucose:flavonoid-3-O-glucosyltransferase (UFGT) showed higher expression levels in the ripening stage, which may relate to the accumulation of anthocyanidins. This study provides comprehensive insights into flavonoid metabolism and berry coloration in Vitis rotundifolia. 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

The occurrence of anthocyanins in rice (Oryza sativa) and barley (Hordeum vulgare) varies among cultivars, with pigmented varieties (e.g., black rice and purple barley) accumulating higher concentrations due to genetic and environmental factors. The biosynthesis of anthocyanins is regulated by a complex network of structural and regulatory genes. Key enzymes in the pathway include chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), anthocyanidin synthase (ANS), and UDP-glucose flavonoid 3-O-glucosyltransferase (UFGT). These genes are tightly controlled by transcription factors (TFs) from the MYB, bHLH (basic helix–loop–helix), and WD40 repeat families, which form the MBW (MYB-bHLH-WD40) regulatory complex. In rice, OsMYB transcription factors such as OsMYB3, OsC1, and OsPL (Purple Leaf) interact with OsbHLH partners (e.g., OsB1, OsB2) to activate anthocyanin biosynthesis. Similarly, in barley, HvMYB genes (e.g., HvMYB10) coordinate with HvbHLH TFs to regulate pigment accumulation. Environmental cues, such as light, temperature, and nutrient availability, further modulate these TFs, influencing the production of anthocyanin. Understanding the genetic and molecular mechanisms behind the biosynthesis of anthocyanins in rice and barley provides opportunities for the development of biofortification strategies that enhance their nutritional value. Full article

Nekemias grossedentata (Hand.-Mazz.) J. Wen & Z. L. Nie is a medicinal and edible plant with a high dihydromyricetin (DHM) content in its bud tips. Vine tea made from its bud tips has served as a health tea and Chinese herbal medicine for nearly 700 years. However, the molecular mechanisms underlying the high DHM content in N. grossedentata bud tips remain inadequately elucidated. This study conducted qualitative and quantitative analyses of bud tip flavonoids utilizing HPLC and targeted metabolomics. Core genes influencing the substantial synthesis of DHM in N. grossedentata were identified through integrated transcriptome and metabolome analyses. The results revealed that 65 flavonoid metabolites were detected in bud tips, with DHM as the predominant flavonoid (37.5%), followed by myricetin (0.144%) and taxifolin (0.141%). Correlation analysis revealed a significant positive correlation between NgF3′5′H3 expression and DHM content. Co-expression analysis and qRT-PCR validation demonstrated a significant positive correlation between NgMYB71 and NgF3′5′H3, with consistent expression trends across three periods and four tissues. Consequently, NgF3′5′H3 and NgMYB71 were identified as core genes influencing the substantial synthesis of DHM in N. grossedentata. Elevated NgMYB71 expression in bud tips induced high NgF3′5′H3 expression, facilitating extensive DHM synthesis in bud tips. Molecular docking analysis revealed that NgF3′5′H3 had a strong binding affinity for taxifolin. NgF3′5′H3 was the pivotal core node gene in the dihydromyricetin biosynthesis pathway in N. grossedentata and was highly expressed in bud tips. The strong specific binding of NgF3′5′H3 to dihydromyricetin precursor metabolites catalyzed their conversion into DHM, resulting in higher DHM contents in bud tips than in other tissues or plants. This study aimed to elucidate the molecular mechanisms underlying the substantial synthesis of DHM in N. grossedentata, providing a theoretical foundation for enhancing DHM production and developing N. grossedentata resources. Full article

Melatonin (MT) is an elicitor that stimulates phenolic compounds biosynthesis and accumulation in fruits and vegetables. However, its role in regulating phenolic compounds and the phenylpropane metabolism during pepper ripening is unclear. To investigate how exogenous MT regulates phenolic compounds biosynthesis during pepper ripening, pepper plant surfaces were sprayed with different MT concentrations (0 and 100 µmol·L⁻¹) 10 days after anthesis. MT treatment improved pepper fruits quality. In particular, total phenolics and flavonoids compounds levels were elevated, indicating that MT affected phenolic compounds metabolism. Furthermore, metabolomics identified 15 substances exhibiting high fold-change values after MT treatment, including chlorogenic acid, gallic acid, ferulic acid, caffeic acid, cynarin, p-coumaric acid, cinnamic acid, gentianic acid, benzoic acid, sinapic acid, p-hydroxybenzoic acid, protocatechuic acid, rutin, quercetin, and kaempferol. Shikimate dehydrogenase, phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, 4-coumarate-Coa ligase, chalcone synthase, and chalcone isomerase activities were also evaluated. MT upregulated the expression of genes involved in phenolic compounds synthesis during pepper ripening and that of corresponding genes involved in the endogenous MT anabolic pathway, promoting endogenous. The polyphenolics and carbohydrates are indicators of the botanical and geographical origin of Serbian autochthonous clones of red spice MT synthesis throughout pepper ripening. In summary, exogenous MT accelerates phenolic compounds synthesis in pepper fruits by activating phenylpropane metabolism and modulating endogenous hormone signaling networks. This is expected to offer a revolutionary strategy to reinforce pepper plants resistance and quality. Full article

Plant cell suspension cultures offer a sustainable method for producing valuable secondary metabolites, such as bioactive pentacyclic triterpenes. This study established a high-triterpene-yielding cell suspension culture from the apple cultivar “Cox Orange Pippin”. Through transcriptomic analysis and triterpene profiling across growth phases, we uncovered complex regulatory networks that govern biomass production and triterpene biosynthesis. Key biological processes, including cell cycle regulation, cell wall biosynthesis, lipid metabolism, and stress response mechanisms, play pivotal roles in culture dynamics. Differential gene expression linked to these processes revealed how the culture adapts to growth conditions and nutrient availability at each growth phase. Methyl jasmonate elicitation enhanced phenylpropanoid and flavonoid biosynthesis, along with specific triterpene production pathways, highlighting its potential for optimizing secondary metabolite production. Key enzymes, such as oxidosqualene cyclase 4 and a putative C-2α hydroxylase, were identified as promising targets for future metabolic engineering efforts. This study represents the first in-depth report on the molecular mechanisms underlying plant cell growth in bioreactors, specially focusing on a cell suspension culture derived from a semi-russeted apple cultivar. The findings reveal key regulatory pathways in biomass accumulation and triterpene production, offering valuable insights for optimizing bioreactor cultures for industrial applications. Full article

The diversity in anthocyanin flower pigmentation is vital in the ornamental plant market. To understand the regulation of the corona filament pigmentation of the Passiflora flower, we investigated the anthocyanin profiles of five distinct species (P. violacea, P. caerulea, P. edulis, P. incarnata, and P. coccinea) using HPLC-MS. A total of 14 anthocyanins, differentially distributed in the analyzed species, were identified as responsible for the differences in corona color, which can be attributed to different ratios of pelargonidin, cyanidin, and delphinidin. Additionally, we evaluated the expression of some biosynthetic genes, including dehydroflavonol reductase (DFR), flavonoid 3′-hydroxylase (F3′H), and flavonoid 3′,5′-hydroxylase (F3′5′H). F3′H seems to regulate the accumulation of cyanidins, F3′5′H determines blue pigmentation, and DFR enhances the biosynthesis of pelargonidins. Furthermore, three genes coding for key transcription factors, Myeloblastosis (MYB), basic helix-loop-helix (bHLH), and WD repeat protein (WD40), were examined using qPCR. The results confirm that such genes regulate anthocyanin biosynthesis and provide insight into the molecular mechanisms that underlie pigment biosynthesis for application in biotechnologies. Full article

Background: Scientific and rational fertilizer management can not only improve the yield and quality of hazelnut (Corylus heterophylla × Corylus avellana) but also reduce the negative impact on the environment. Methods: Liquid Chromatography–tandem Mass Spectrometry (LC-MS/MS) technology was used to reveal the contents of various metabolites in hazelnut seedlings, and differential metabolites were screened by principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). Results: The results showed that a total of 178 up-regulated differential metabolites (Fold change > 1) and 175 down-regulated differential metabolites (Fold change < 1) were detected in 6 comparison groups (DWF0 vs. DWF4, DWF0 vs. DWF5, DWF0 vs. DWF6, DWF4 vs. DWF5, DWF4 vs. DWF6, DWF5 vs. DWF6). Interestingly, the flavonoid metabolic pathway was dramatically enriched, and it was involved in each fertilization combination. The metabolites of the flavonoid pathway in different fertilized and unfertilized groups were compared and analyzed, which displayed that metabolites tricetin, eriodictyol, garbanzol, apigenin, and biochanin A were significantly up-regulated, while garbanzol and astraglin were significantly down-regulated. More interestingly, the determination of flavonoid content and real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) displayed that the application of trace element water-soluble fertilizer could significantly enhance the flavonoid content and the expression of genes related to the flavonoid biosynthesis pathway, such as phenylalanine ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H), with the DWF4 treatment displaying the most significant values. Conclusions: Overall, the application of trace element water-soluble fertilizer (especially the DWF4 treatment) markedly affected the changes in key metabolites of the flavonoid pathway and the expression levels of key genes, thus promoting the growth and development of the hazelnut, which offers an important starting point for future analysis through genetic engineering. Full article

Drought stress significantly impairs the output of tea plants and the quality of tea products. Although Serendipita indica has demonstrated the ability to enhance drought tolerance in host plants, its impact on tea plants (Camellia sinensis) experiencing drought stress is unknown. This study assessed the response of tea plants by inoculating S. indica under drought conditions. Phenotypic and physiological analyses demonstrated that S. indica mitigated drought damage in tea plants by regulating osmotic equilibrium and antioxidant enzyme activity. Metabolome analysis showed that S. indica promoted the accumulation of flavonoid metabolites, including naringin, (-)-epiafzelechin, naringenin chalcone, and dihydromyricetin, while inhibiting the content of amino acids and derivatives, such as homoarginine, L-arginine, N6-acetyl-L-lysine, and N-palmitoylglycine, during water deficit. The expression patterns of S. indica-stimulated genes were investigated using transcriptome analysis. S. indica-induced drought-responsive genes involved in osmotic regulation, antioxidant protection, transcription factors, and signaling were identified and recognized as possibly significant in S. indica-mediated drought tolerance in tea plants. Particularly, the flavonoid biosynthesis pathway was identified from the metabolomic and transcriptomic analysis using Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Moreover, flavonoid biosynthesis-related genes were identified. S. indica-inoculation significantly upregulated the expression of cinnamate 4-hydroxylase (C4H), chalcone synthase (CHS), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), anthocyanidin reductase (ANR), and leucoanthocyanidin reductase (LAR) genes compared to uninoculated plants subjected to water stress. Consequently, we concluded that S. indica inoculation primarily alleviates drought stress in tea plants by modulating the flavonoid biosynthesis pathway. These results will provide insights into the mechanisms of S. indica-enhanced drought tolerance in tea plants and establish a solid foundation for its application as a microbial agent in the management of drought in tea plants cultivation. Full article