Search Results (90)

Anthocyanins can enhance the nutritional and market value of Dioscorea alata L. They are synthesized in a tissue-specific manner in the peel and flesh of tubers in some Dioscorea alata L. varieties, yet the regulatory mechanisms behind this remain unclear. In order to identify the genes involved in anthocyanin synthesis between the skin and flesh of D. alata, three varieties exhibiting distinct anthocyanin phenotypes were studied. A comprehensive analysis of the skin and flesh was conducted to identify the presence of anthocyanins. Three identical anthocyanins were identified in both the skin and the flesh: Alatanin C, Cya-3-O(2-O-glucosyl) glu, and Cya-3-O(6-O-sinapoyl) sop-5-O-glu. To investigate the anthocyanin biosynthesis pathways in purple D. alata skin and flesh, transcriptome sequencing was performed on both tissues. This analysis identified eight anthocyanins in the skin and fifteen in the flesh. Cyanidin-type anthocyanins were found to be the most abundant type of anthocyanin in both skin and flesh. Subsequent identification of 30 key genes associated with anthocyanin biosynthesis revealed 4CL (4-coumarate CoA ligase) and DFR (dihydroflavonol 4-reductase) as potential key regulators of anthocyanin variation between skin and flesh. This study is of considerable theoretical and practical significance for the genetic enhancement of anthocyanin traits in D. alata. Full article

Anthocyanins are key antioxidants that play a significant role in plant responses to adverse stresses, including nitrogen deficiency. However, research on the metabolic and transcriptional regulation of anthocyanins in black soybean seed coats under low-nitrogen conditions remains limited. Here, we report that low-nitrogen treatment significantly alters the accumulation of anthocyanin metabolites and the gene expression profiles in black soybeans. Specifically, a greater number of differential anthocyanin metabolites are induced under low-nitrogen conditions, which contributes to the accumulation of anthocyanins in the seed coat. GO and KEGG enrichment analyses revealed that the differentially expressed genes (DEGs) are mainly enriched in multiple antioxidant pathways involved in responding to low-nitrogen stress; in flavonoid and phenylalanine metabolic pathways, as well as protein processing in endoplasmic reticulum, which are associated with anthocyanin biosynthesis; and in plant hormone signal transduction pathways involved in the regulation of anthocyanin accumulation. The expressions of genes encoding key enzymes in anthocyanin biosynthesis, such as dihydroflavonol 4-reductase (DFR) and O-methyltransferase (OMT), as well as genes encoding the blue light photoreceptor cryptochrome (CRY) and proteins related to cellular autophagy, were upregulated under low-nitrogen treatment. This suggests that these genes may play a key role in low-nitrogen-induced anthocyanin accumulation. This study provides a theoretical basis and novel perspective for understanding the regulatory mechanism underlying low-nitrogen-induced anthocyanin accumulation in black soybeans. Full article

The Northeast region in China is a major maize-producing area; however, low-temperature stress (TS) limits maize (Zea mays L.) seed germination, affecting population establishment and yield. In order to systematically explore the regulation mechanism of maize radicle which is highly sensitive to low-temperature environment response to TS, seeds of ZD958 and DMY1 were used to investigate germination responses under 15 °C (control) and 5 °C (TS) conditions. Phenotypic, physiological, transcriptomic, and metabolomic analyses were conducted on the radicles after 48 h of TS treatment. TS caused reactive oxygen species (ROS) imbalance and oxidative damage in radicle cells, inhibiting growth and triggering antioxidant defenses. Integrated transcriptomic and metabolomic analyses revealed that flavonoid metabolism may play a pivotal role in radicle responses to TS. Compared with the control treatment, ZD958 and DMY1 under TS treatment significantly increased (p < 0.01) the total flavonoid content, total antioxidant capacity, 4-coumarate-CoA ligase activity, and dihydroflavonol 4-reductase activity by 15.99% and 16.01%, 18.41% and 18.54%, 63.54% and 31.16%, and 5.09% and 7.68%, respectively. Despite genotypic differences, both followed a shared regulatory logic of “low-temperature signal-driven—antioxidant redirection—functional synergy.” This enabled ROS scavenging, redox balance, and antioxidant barrier formation, ensuring basal metabolism and radicle development. 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

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

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 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

Bamboo orchid (Arundina graminifolia), a fast-growing evergreen terrestrial orchid with year-round flowering capacity, exhibits limited germplasm resources for white floral variants despite its ornamental significance. This study investigates the molecular basis of natural white flower formation through comparative analysis of purple- and white-flowered variants across bud, post-bud, and blooming stages. Histological examination revealed anthocyanin accumulation restricted to two to three upper epidermal cell layers in purple petals, while white petals showed complete pigment absence. Transcriptome profiling coupled with RT-qPCR validation identified eleven differentially expressed structural genes in anthocyanin biosynthesis. Notably, AgDFR expression remained undetectable across all white-flower developmental stages. Sequence analysis demonstrated identical 3030 bp promoter regions of AgDFR between two variants, while white-flower AgDFR coding sequences contained over 107 bp insertion after the 330th nucleotide, causing premature translation termination. Molecular marker validation confirmed the presence of a diagnostic 472 bp fragment in all colored variants (13 purple/pink lines) and its absence in white phenotypes. This study establishes that insertional mutagenesis in AgDFR’s coding region underlies natural white flower in A. graminifolia. The developed molecular marker enables reliable differentiation of white-flowered variants from pigmented counterparts, providing valuable tools for germplasm management and breeding programs. Full article

Dihydroflavonol 4-reductase (DFR) genes contribute greatly to anthocyanin biosynthesis in plants. Up to now, however, research on the DFR gene family and the key anthocyanin-related DFR members in blueberries (Vaccinium corymbosum) has been limited. In this study, we performed a genome-wide identification of the blueberry DFR gene family, identifying 36 VcDFR genes categorized into five subfamilies. Gene expression analysis showed that three Subfamily III members (VcDFR11/29/34) and four Subfamily V members (VcDFR4/7/30/33) are highly expressed in blueberry fruits, particularly at late ripening stages. Transient overexpression analysis in apple fruits verified the contributions of VcDFR11 and VcDFR30 to anthocyanin biosynthesis, with VcDFR11 showing better promoting effects. Blueberry fruit-based transient overexpression further confirmed the promoting effects of VcDFR11 on anthocyanin accumulation and the expression of anthocyanin-related structural genes (especially its downstream anthocyanindin synthase (ANS) and UDP-glucose: flavonoid 3-O-glycosyltransferase (UFGT) genes). The VcDFR11 promoter contains binding sites for both bHLH and MYB transcription factors (TFs). Consistently, yeast one-hybrid and dual-luciferase assays confirmed that anthocyanin-related VcMYB-1 and VcbHLHs can bind to and activate the VcDFR11 promoter. Furthermore, co-overexpressing VcMYB-1/VcbHLHs with VcDFR11 led to much higher anthocyanin accumulation than overexpressing VcDFR11 alone, indicating that these TFs positively regulate anthocyanin biosynthesis by upregulating VcDFR11. In summary, our study characterized the blueberry DFR gene family and demonstrated the role of VcDFR11 in anthocyanin biosynthesis. 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

The formation of flower color is closely related to anthocyanin synthesis. In this study, flowers of Bletilla striata (Orchidaceae) exhibiting distinct color morphs were collected and analyzed. The HPLC results showed significantly higher total flavonoid and anthocyanin contents in purple flowers compared to pink counterparts, with increases of 2.20-fold (p < 0.01) and 15.22-fold (p < 0.01), respectively. Cyanidin was the predominant anthocyanin in B. striata. Resequencing analyses highlighted SNP as the primary variation associated with color divergence. A comprehensive screen identified 61 genes encoding enzymes critical to the flavonoid and anthocyanin biosynthesis pathways in B. striata. Among these, 16 flower-specific genes exhibited high expression levels and harbored SNP variations. Notably, a premature stop codon was identified in a gene encoding dihydroflavonol 4-reductase (DFR), leading to truncated protein synthesis and potential disruption of anthocyanin production. Further, the heterologous overexpression of BsDFR4 in Phalaenopsis aphrodite changed petal color from white to yellow-green, demonstrating that it indeed played a regulatory role in the formation of flower color. Furthermore, yeast one-hybrid assays confirmed that transcription factors BsMYB36 and BsMYB51 could directly bind to the BsDFR4 promoter, suggesting their synergistic regulation of anthocyanin biosynthesis. These results provided a conceptual basis for insights into the formation of different flower colors in Orchidaceae. Full article

Hydroxytyrosol is a natural phenolic compound found in olives. Phenylacetaldehyde reductase (PAR) is a key enzyme in the final step of the hydroxytyrosol biosynthesis pathway in olives. However, genome-wide studies on the PAR gene family in olives have not been reported. In this study, 21 genes were identified through a genome-wide analysis. Phylogenetic analysis classified these genes into three subgroups: PAR, CCR (Cinnamoyl-CoA reductase), and DFR (Dihydroflavonol 4-reductase). Expression pattern analysis suggested that genes within these subfamilies may play crucial roles in the biosynthesis of polyphenols, lignin, and anthocyanins, respectively. Three-dimensional structural modeling and molecular docking of the OePAR1 revealed that hydrogen bonds, hydrophobic interactions, and π–π stacking interactions collectively influence the affinity between PAR and its substrates. Residues at the active site form hydrogen bonds, with variations contributing to substrate specificity. The substrate with the strongest affinity for OePAR1 was identified as 3,4-dihydroxyphenylacetaldehyde (3, 4-DHPAA), with a binding energy of −4.98 kcal/mol, in agreement with previous enzymatic activity validation. Subcellular localization studies revealed that OePAR1 is localized to the chloroplast. This study provides essential insights into the biological functions of OePARs in olives and lays the groundwork for enhancing olive oil quality through genetic engineering. Full article

Background: Dihydroflavonol 4-reductase (DFR) is a key enzyme in the flavonoid biosynthetic pathway that regulates anthocyanin and proanthocyanidin accumulation in plants. Although DFR genes have been studied in various species, their origin of the DFR gene family, its distribution across the plant kingdom, and the reasons behind the emergence of different DFR subtypes Methods: This study performed a whole-genome analysis of DFR genes in 237 plant species, including algae, mosses, ferns, gymnosperms, and angiosperms, integrating phylogeny, conserved motifs, duplication mechanisms, positive selection, and expression pattern analyses. Results: These results indicate that the DFR gene family originated from the common ancestor of extant ferns and seed plants, and the emergence of asparagine (Asn)-type and aspartic (Asp)-type DFRs is associated with gymnosperms. Notably, we report for the first time the presence of Asn-type, Asp-type, and arginine (Arg)-type DFRs in some species, which breaks the previous notion that Arg-type DFRs are exclusive to ferns. Tandem duplication is considered the primary driving force behind the expansion of the DFR family and is associated with the formation of different DFR subtypes. Furthermore, Asn-type DFRs were highly expressed during the early stages of seed development, suggesting their important role in seed development. Conclusions: Overall, this study revealed the dynamic evolutionary trajectory of the DFR gene family in plants, providing a theoretical foundation for future research on DFR genes. 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

Waxy maize (Zea mays L. sinensis kulesh) contains a lot of nutrients, and has a long history of cultivation and extensive consumption. In this study, six waxy maize varieties of white (J18 and W2000), yellow (J41 and J7), and black (J10 and J20) were selected as experimental materials, and the functional nutrients and the differences in anthocyanin anabolic pathways in maize kernels at 14, 18, 22, and 26 days after pollination were determined. The result show that the varieties and kernel development stages had significant effect on the carotenoid, soluble sugar, vitamin C, anthocyanin, and mineral element content. The black waxy maize varieties had a higher anthocyanin content, which plays an important role in maize kernel coloration, whereas the yellow and black waxy maize varieties exhibit a greater abundance of mineral elements. Furthermore, the phenylalanine content, as well as the activities of phenylalanine ammonia lyase (PAL), chalcone isomerase (CHI), dihydroflavonol reductase (DFR), and flavonoid 3-glucosyltransferase (UFGT), played a significant role in the anthocyanin biosynthetic pathway. In conclusion, the comprehensive functional quality of waxy maize decreased with the delay of kernel development stage, and the black waxy maize varieties demonstrated superior functional quality. The PAL and CHI played a primary role in the initial phase of anthocyanin accumulation, while UFGT gradually assumed control in the subsequent stages. Full article