Search Results (117)

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

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

Drought stress significantly hinders the cultivation of medicinal plants such as licorice (Glycyrrhiza uralensis), valued for its bioactive compounds, glycyrrhizin, and liquiritin. This study aims to investigate how co-inoculation with arbuscular mycorrhizal fungus Rhizophagus irregularis and Trichoderma harzianum can enhance licorice drought tolerance and secondary metabolite production, providing insights for sustainable agriculture in arid regions. The results demonstrate that inoculation with R. irregularis significantly improved biomass, drought stress tolerance, and increased glycyrrhizin and liquiritin concentrations by 29.9% and 3.3-fold, respectively, particularly under drought conditions. Co-inoculation with T. harzianum further boosted glycyrrhizin yield by 93.7%, indicating a synergistic relationship between the two microbes. The expression of key biosynthetic genes, including squalene synthase (SQS1) for glycyrrhizin and chalcone synthase (CHS) for liquiritin, was significantly upregulated, enhancing water use efficiency and the biosynthesis of secondary metabolites. Nutrient analysis showed improved phosphorus uptake, alongside reduced root carbon and nitrogen concentrations, leading to greater nutrient utilization efficiency. These findings suggest that co-inoculating R. irregularis and T. harzianum is a promising approach to improving licorice growth and medicinal quality under drought stress, with broad applications for sustainable crop management. Full article

Small RNAs (sRNAs) are pivotal in regulating gene expression and are involved in a diverse array of biological processes. Among these, microRNAs (miRNAs) and phased small interfering RNAs (phasiRNAs) have been extensively investigated over the past decades. We conducted an in-depth analysis of deep sequencing data from the gymnosperm Ginkgo biloba, encompassing sRNA, transcriptome, and degradome libraries. Our analysis identified a total of 746 miRNAs and 654 phasiRNA precursor (PHAS) loci, with 526 (80%) of the PHAS loci predicted to be triggered by 515 miRNAs (69%). Several miRNA-PHAS modules, particularly the miR159/miR319-PHAS module, were found to potentially regulate reproductive development by targeting GAMYB genes and triggering phasiRNA biogenesis. The miR390-PHAS module appears to be involved in flavonoid biosynthesis by targeting key enzyme genes such as chalcone synthase (CHS) and anthocyanin synthase (ANS). Through target gene identification and coexpression analysis, we uncovered two distinct models of complex regulatory networks: growth-related factors like ARF and GRF seem to be regulated exclusively by miRNAs (Model 1), while certain disease resistance-related genes are predicted to be regulated by both miRNAs and phasiRNAs (Model 2), indicating diverse regulatory mechanisms across different biological processes. Overall, our study provides a comprehensive annotation of miRNA and PHAS loci in G. biloba and elucidates a post-transcriptional regulatory network, offering novel insights into sRNA research in gymnosperms. Full article

Iris dichotoma Pall., renowned for its high ornamental value, is frequently cultivated in flowerbeds and courtyards, endowing garden landscapes with unique allure. Dark-hued flowers are widely regarded as more aesthetically appealing. This study utilized the petals of two distinct Iris dichotoma Pall. phenotypes as research materials to investigate the underlying mechanism of flower color formation. The purple-flowered Iris dichotoma Pall. was designated as Group P, and the white-flowered one as Group W. A comprehensive integrative analysis of the transcriptome and metabolome of the two petal types was carried out. Metabolomic analysis revealed that the contents of several anthocyanin derivatives, including delphinidin, petunidin, malvidin, peonidin, and procyanidin, were significantly higher in purple petals compared to white petals, with delphinidin exhibiting the highest content. The transcriptomic analysis detected 6731 differentially expressed genes (DEGs) between the white and purple petal types. Specifically, 3596 genes showed higher expression levels in purple petals, while 3135 genes exhibited lower expression levels in purple petals compared to white petals. Ten phenylalanine ammonia-lyase (PAL) genes, two chalcone synthase (CHS) genes, one anthocyanidin reductase (ANR) gene, one 4-coumarate-CoA ligase (4CL) gene, one dihydroflavonol 4-reductase (DFR) gene, one flavanone 3′-hydroxylase (F3′H) gene, and one flavonol synthase (FLS) gene were identified; they all had purple petals displaying higher expression levels than white petals. This research uncovers the potential formation mechanism of anthocyanins in the two Iris dichotoma Pall. types, thereby furnishing a theoretical foundation for floral breeding endeavors. Full article

Background: Chalcone synthase (CHS) functions as a pivotal and initiating enzyme in the flavonoid biosynthesis pathway within plants, playing a crucial role in the accumulation and metabolic processes of flavonoids. Despite its importance, there has been no comprehensive analysis or detailed description of the CHS gene family members specifically in Tartary buckwheat. Methods: Based on a comprehensive analysis using multiple bioinformatics approaches and quantitative real−time PCR (qRT−PCR) technology, this study systematically identified and characterized the CHS gene family members from the complete genome sequence of Tartary buckwheat. Results: In this study, we identified a total of 14 FtCHS genes (FtCHS1−FtCHS14) in Tartary buckwheat. Analysis of gene structure and protein motifs showed that most FtCHS genes consist of two exons and a single intron, featuring conserved Chal−sti−synt_N and Chal−sti−synt_C domains. Phylogenetic studies suggested that FtCHS genes can be categorized into four primary groups: Groups I, II, III, and IV. Further analysis of the promoter regions revealed that the FtCHS family genes contain multiple cis−acting elements that respond to light, plant hormones, stress, and developmental cues. By combining phylogenetic analysis with gene expression data, we found that the genes in Group II (FtCHS3, FtCHS4, FtCHS5, and FtCHS6) exhibit significantly elevated expression levels specifically in flowers. Conclusions: Our study indicated that FtCHS is a gene superfamily comprising at least four functional members. The expression patterns of these FtCHS genes suggest their probable involvement in flower−related biological processes in Tartary buckwheat. This work provides fundamental insights into the comprehensive understanding of the functional roles of the CHS gene family in Tartary buckwheat. Full article

The seed-coat color and seed size have an impact on both the evolutionary fitness and the grain yield of crops. Soybean is a major oil crop, and the seed-coat color and seed size exhibit natural diversity among the different soybean varieties. Here, we found an R2R3-MYB transcription factor of GmMYB62, which shows a significant increase in expression as the seed-coat color changes from yellow to black in different soybean varieties. The GmMYB62 was specifically highly expressed in reproductive organs, especially in floral organs in soybeans. The GmMYB62 encodes a nuclear protein that contains two MYB domains. In the phylogenetic analysis, the GmMYB62 was relatively conserved after the divergence of the monocots and dicots, and it also grouped with transcriptional repressors of MYBs in anthocyanin synthesis. The GmMYB62 was overexpressed in Arabidopsis and the seeds displayed a pale-brown coat in GmMYB62 overexpression lines, in contrast to the dark-brown seed coat observed in wild-type of Col-0. The anthocyanin content in the GmMYB62 overexpression lines was dramatically reduced when compared to Col-0. Additionally, the seeds in overexpression lines showed shorter lengths, larger widths, and lower thousand-seed weights than those in Col-0. Furthermore, the genes related to anthocyanin synthesis and seed size regulation were investigated, and expression of eight genes that involved in anthocyanin synthesis pathway, like chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), and anthocyanidin synthase (ANS) were severely inhibited in the GmMYB62 overexpression lines when compared to Col-0. In addition, the ARGOS-LIKE (ARL), B-Type Cyclin 1 (CYCB1), and enhancer of DA1-1 (EOD3), which govern cell expansion and proliferation, were highly expressed in GmMYB62 overexpression lines when compared to Col-0. Overall, this study sheds new light on the control of seed-coat color and seed size by GmMYB62 and provides potentially valuable targets for improving crop seed quality. Full article

High-salinity stress induces severe oxidative damage in plants, leading to growth inhibition through cellular redox imbalance. Chalcone synthase (CHS), a pivotal enzyme in the flavonoid biosynthesis pathway, plays critical roles in plant stress adaptation. However, the molecular mechanisms underlying CHS-mediated salt tolerance remain uncharacterized in Areca catechu L., a tropical crop of high economic and ecological significance. Here, we systematically identified the CHS gene family in A. catechu and revealed tissue-specific and salt-stress-responsive expression patterns, with AcCHS5 exhibiting the most pronounced induction under salinity. Transgenic Arabidopsis overexpressing AcCHS5 displayed enhanced salt tolerance compared to wild-type plants, characterized by elevated activities of antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), increased flavonoid accumulation, and reduced reactive oxygen species (ROS) accumulation. Furthermore, we identified the transcription factor AcMYB176 as a direct activator of AcCHS5 through binding to its promoter. Our findings demonstrate that the AcMYB176-AcCHS5 regulatory module enhances salt tolerance by orchestrating flavonoid biosynthesis and ROS scavenging. This study provides functional evidence of CHS-mediated salt adaptation in A. catechu and highlights its potential for improving stress resilience in tropical crops. 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

Controlled-environment crop production often weakens plants’ defense mechanisms, reducing the accumulation of protective phytochemicals essential to human health. Our previous studies demonstrated that short-term supplementation of low-dose ultraviolet (UV) light to the red–green–blue (RGB) spectrum effectively boosts secondary metabolite (SM) synthesis and antioxidant capacity in lettuce. This study explored whether similar effects occur in basil cultivars by supplementing the RGB spectrum with ultraviolet B (UV-B, 311 nm) or ultraviolet C (UV-C, 254 nm) light shortly before harvest. Molecular analyses focused on UV-induced polyphenol synthesis, particularly chalcone synthase (CHS) level, and UV light perception via the UVR8 receptor. The impact of high-energy UV radiation on the photosynthetic apparatus (PA) was also monitored. The results showed that UV-B supplementation did not harm the PA, while UV-C significantly impaired photosynthesis and restricted plant growth and biomass accumulation. In green-leaf (Sweet Large, SL) basil, UV-B enhanced total antioxidant capacity (TAC), increasing polyphenolic secondary metabolites and ascorbic acid (AsA) levels. UV-C also stimulated phenolic compound accumulation in SL basil but had no positive effects in the purple-leaf (Dark Opal, DO) cultivar. Interestingly, while the UV-B treatment promoted UVR8 monomerization in both cultivars, the enhanced CHS level and concomitant SM synthesis were noted only for SL basil. In addition, UV-C also induced CHS activity and SM synthesis in SL basil but clearly in a UVR8-independeted manner. These findings underscore the potential of UV light supplementation for enhancing plant functional properties, highlighting species- and cultivar-specific effects without compromising photosynthetic performance. Full article

Djulis (Chenopodium formosanum Koidz.), a member of the Amaranthaceae family plant, is noted for its vibrant appearance and significant ornamental value. However, the mechanisms underlying color variation in its spikes remain unexplored. This research initially detected the anthocyanin content at different developmental stages of the spike and subsequently utilized an integrative approach, combining targeted metabolomics, transcriptomics, and untargeted metabolomics analyses, to elucidate the mechanisms of anthocyanin biosynthesis in the spikes of djulis. The results of the combined multi-omics analysis showed that the metabolites associated with anthocyanin synthesis were mainly enriched in the flavonoid biosynthesis pathway (ko00941) and the anthocyanin biosynthesis pathway (ko00942). With the maturation of djulis spikes, a total of 28 differentially expressed genes and 17 differentially expressed metabolites were screened during the transition of spike color from green (G) to red (R) or orange (O). Twenty differentially expressed genes were selected for qRT-PCR validation, and the results are consistent with transcriptome sequencing. The upregulation of seven genes, including chalcone synthase (CfCHS3_1, CfCHS3_2, CfCHS3_3), flavanone 3-hydroxylase (CfF3H_3), flavonoid 3′5′-hydroxylase (CfCYP75A6_1), dihydroflavonol reductase (CfDFRA), and glucosyltransferase (Cf3GGT), promotes the formation and accumulation of delphinidin 3-sambubioside and peonidin 3-galactoside. The research results also showed that anthocyanins and betalains can coexist in the spike of djulis, and the reason for the change in spike color during development may be the result of the combined action of the two pigments. A possible regulatory pathway for anthocyanin biosynthesis during the spike maturation was constructed based on the analysis results. The results provide a reference and theoretical basis for further studying the molecular mechanism of anthocyanin regulation of color changes in Amaranthaceae plants. Full article

Chalcone synthase (CHS), the first key structural enzyme in the flavonoid biosynthesis pathway, plays a crucial role in regulating plant responses to abiotic stresses and hormone signaling. However, its molecular functions remain largely unknown in Phyllostachys edulis, which is one of the most economically and ecologically important bamboo species and the most widely distributed one in China. This study identified 17 CHS genes in Phyllostachys edulis and classified them into seven subgroups, showing a closer evolutionary relationship to CHS genes from rice. Further analysis of PeCHS genes across nine scaffolds revealed that most expansion occurred through tandem duplications. Collinearity analysis indicated strong evolutionary conservation among CHS genes. Motif and gene structure analyses confirmed high structural similarity, suggesting shared functional characteristics. Additionally, cis-acting element analysis demonstrated that PeCHS genes are involved in hormonal regulation and abiotic stress responses. RNA-Seq expression profiles in different bamboo shoot tissues and heights, under various hormone treatments (gibberellin (GA), naphthaleneacetic acid (NAA), abscisic acid (ABA), and salicylic acid (SA)), as well as salinity and drought stress, revealed diverse response patterns among PeCHS genes, with significant differential expression, particularly under hormone treatments. Notably, PeCHS14 consistently maintained high expression levels, suggesting its key role in stress response mechanisms. qRT-PCR analysis further validated the expression differences in five PeCHS genes under GA and ABA treatments. Subcellular localization analysis demonstrated that PeCHS14 and PeCHS15 proteins are localized in the nucleus. This study provides a foundation for investigating the potential functions of PeCHS genes and identifies candidate genes for future research on the responses of Phyllostachys edulis to abiotic stresses and hormone signaling. Full article

White clover (Trifolium repens) is vulnerable to drought stress. In response to abiotic stress, plants are regulated by NAC transcription factors. The NAC in white clover has not been thoroughly documented until recently. We have identified one white clover NAC transcription factor called TrNAC002. TrNAC002’s coding sequence is localized to specific regions on the 3P and 5O chromosomes of white clover and is part of a single-copy nuclear gene. Subcellular localization demonstrates that TrNAC002 is located in the nucleus, while the transcriptional activity assay indicates its transcriptional activity. Arabidopsis plants overexpressing TrNAC002 (OE) exhibit enlarged leaves and increased lateral root growth compared to the wild type (WT). Additionally, the expression levels of the shoot apical meristem (SAM), WUSCHEL (WUS), DNA-binding protein (DBP), and auxin-induced in root cultures3 (AIR3) genes are significantly higher in OE as compared to WT. These findings imply that TrNAC002 could promote vegetative growth by increasing the expression of these genes. Under natural drought stress, OE can survive in dry soil for a longer period of time than WT. Furthermore, OE exhibits a lower level of reactive oxygen species (ROS) level and a higher content of flavonoids than WT. This is also positively correlated with an increased flavonoid content. In white clover, the expression of TrNAC002, chalcone synthase (CHS), and chalcone isomerase (CHI) in leaves demonstrates significant upregulation after drought stress and ABA treatment, as does the flavonoid content. However, the pTRV-VIGS experiment suggests that pTRV2-TrNAC002 white clover shrinks compared to the Mock and Water controls. Additionally, pTRV2-TrNAC002 white clover displays a statistically higher malondialdehyde (MDA) content than the Mock and Water controls, and a significantly lower level of total antioxidant activities, flavonoid content, CHS and CHI relative expression than that of the Mock and Water controls. These findings indicate that TrNAC002 responds to drought and modulates flavonoid biosynthesis in white clover. This study is the first to suggest that TrNAC002 likely responds to drought via ABA and enhances plant drought resistance by synthesizing flavonoids. Full article

Dendrobium devonianum is an important medicinal plant, rich in flavonoid, with various pharmacological activities such as stomachic and antioxidant properties. In this study, we integrated metabolome and transcriptome analyses to reveal metabolite and gene expression profiles of D. devonianum, both green (GDd) and purple-red (RDd) of semi-annual and annual stems. A total of 244 flavonoid metabolites, mainly flavones and flavonols, were identified and annotated. Cyanidin and delphinidin were the major anthocyanidins, with cyanidin-3-O-(6″-O-p-Coumaroyl) glucoside and delphinidin-3-O-(6″-O-p-coumaroyl) glucoside being the highest relative content in the RDd. Differential metabolites were significantly enriched, mainly in flavonoid biosynthesis, anthocyanin biosynthesis, and flavone and flavonol biosynthesis pathways. Transcriptomic analysis revealed that high expression levels of structural genes for flavonoid and anthocyanin biosynthesis were the main reasons for color changes in D. devonianum stems. Based on correlation analysis and weighted gene co-expression network analysis (WGCNA) analysis, CHS2 (chalcone synthase) and UGT77B2 (anthocyanidin 3-O-glucosyltransferase) were identified as important candidate genes involved in stem pigmentation. In addition, key transcription factors (TFs), including three bHLH (bHLH3, bHLH4, bHLH5) and two MYB (MYB1, MYB2), which may be involved in the regulation of flavonoid biosynthesis, were identified. This study provides new perspectives on D. devonianum efficacy components and the Dendrobium flavonoids and stem color regulation. Full article

The color variation of the leaves in autumn is a significant ornamental feature of Acer truncatum Bunge, especially when the leaves gradually become redder. Many studies focused on leaf color changes; however, less research has been conducted on the mechanism by which A. truncatum’s autumn leaves turn red. Red, middle and green leaves of Acer truncatum were used as the study materials to evaluate their flavonoid-related metabolites and infer gene and metabolite expression patterns in conjunction with transcriptome expression. For a start, phenotypic and leaf color parameters analyses showed that red leaves had the highest color redness and greenness (a*). In addition, a total of 23 flavonoid-related metabolites were identified through the metabolome, including five anthocyanins. Of them, cyanidin 3-O-β-D-sambubioside, cyanidin 3-O rutinoside, pelargonidin 3-O-3″,6″-O-dimalonylglucoside, delphinidin 3,7-di-O-β-D-glucoside and 3-O-β-D-sambubioside would help the leaves turn red in A. truncatum. Similarly, combined transcriptomics and metabolomics analyses showed that most genes in the flavonoid and anthocyanin biosynthetic pathways were differentially expressed in both types of leaves. Chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR) and anthocyanin synthase (ANS) could affect flavonoid synthesis during leaf color change. This study could provide data for the genetic improvement of maple plants by exploring valuable metabolites and genes in flavonoid synthesis, and enhance the understanding of different developmental stages. Full article