Search Results (72)

Peach (Prunus persica) fruit pigmentation is largely associated with anthocyanin accumulation, whereas colorless flavonols such as kaempferol glycosides may reflect alternative use of shared flavonoid precursors. To examine the relationship between anthocyanin and selected kaempferol glycoside accumulation, we analyzed 15 peach accessions classified by red, white, or yellow flesh pigmentation. Skin color was quantified using the a*/b* ratio, where a* represents redness/greenness and b* represents yellowness/blueness. Red-fleshed accessions showed higher skin a*/b* values and accumulated higher levels of total anthocyanins, particularly cyanidin-3-glucoside, than white and yellow accessions. In contrast, kaempferol-3-rhamnoside preferentially accumulated in white-fleshed accessions. Expression analysis of flavonoid pathway genes showed that dihydroflavonol 4-reductase (PpDFR) was more highly expressed in red accessions, whereas flavonol synthase (PpFLS) was more highly expressed in white accessions; chalcone synthase (PpCHS), flavanone 3-hydroxylase (PpF3H), flavonoid 3′-hydroxylase (PpF3′H), and anthocyanidin synthase (PpANS) showed no significant differences among color groups. Heterologous overexpression of PpF3′H in Arabidopsis thaliana, a well-characterized model plant for flavonoid biosynthesis, was associated with increased seed anthocyanin accumulation and a lower kaempferol-to-quercetin ratio, supporting its catalytic capacity to influence flavonoid composition in an exogenous system. Overall, these results indicate that differential anthocyanin and selected kaempferol glycoside accumulation in peach is associated with the relative expression patterns of branch-related flavonoid genes, particularly PpDFR and PpFLS. This study provides targeted metabolic and transcriptional evidence for understanding peach flesh and skin pigmentation and provides mechanistic insight into flavonoid branch competition linking gene expression patterns with metabolite allocation, and identifies candidate genes for improving fruit color and flavonoid-related nutritional quality. Full article

Flavonoids play critical roles in plant adaptation to abiotic stress by acting as potent antioxidants that regulate reactive oxygen species (ROS) homeostasis. In Atriplex canescens (Pursh) Nutt., a halophytic shrub well-adapted to saline and arid environments, transcriptomic analyses revealed that salt stress induces strong upregulation of flavanone 3-hydroxylase (F3H), a key enzyme in the flavonoid biosynthetic pathway. However, the functional role of AcF3H in stress adaptation remains poorly understood. Here, we cloned the AcF3H gene from A. canescens and generated transgenic Arabidopsis thaliana (L.) Heynh. lines constitutively overexpressing this gene. Overexpression of AcF3H significantly enhanced flavonoid accumulation, as confirmed by DPBA staining and total flavonoid quantification, and selectively upregulated the expression of downstream biosynthetic genes AcDFR and AcANS, which encode the dihydroflavonol 4-reductase (DFR) and anthocyanidin synthase (ANS), respectively. Under salt and drought stress, transgenic lines exhibited improved root elongation, increased shoot and root biomass, and higher relative water content compared to wild-type plants. Mechanistic investigations revealed that AcF3H overexpression led to reduced H₂O₂ accumulation and lower plasma membrane permeability under stress conditions, indicating enhanced antioxidative capacity and cellular membrane stability. These results suggest that AcF3H confers enhanced tolerance to abiotic stresses by promoting flavonoid-mediated ROS homeostasis. Our findings highlight AcF3H as a promising genetic target for engineering salt- and drought-tolerant crops. Full article

Background: Nymphaea atrans exhibits a gradual flower color transition from nearly white to rose-red during anthesis, yet the molecular mechanisms of this phenomenon remain unclear. In the present study, transcriptomic and metabolomic analyses were performed to systematically investigate anthocyanin accumulation patterns and regulatory mechanisms during the color transition of N. atrans. Methods: Petals were collected at three flowering stages: day 1 (D1), day 3 (D3), and day 5 (D5). Targeted metabolomics was performed using UPLC-ESI-MS/MS to profile anthocyanin and other flavonoid metabolites. Transcriptome analysis was conducted via RNA-seq. Differentially accumulated metabolites (DAMs) and differentially expressed genes (DEGs) were identified, followed by functional enrichment and integration analysis. Results: The results revealed significant accumulation of seven anthocyanins, including cyanidin-3-O-arabinoside, cyanidin-3-O-glucoside, cyanidin-3-O-galactoside, cyanidin-3-O-(6″-O-acetyl)-glucoside, at stages D3 (day 3 after flowering, light pink petals) and D5 (day 5 after flowering, deep pink petals), accompanied by the upregulation of key enzyme-encoding genes, chalcone synthase, chalcone isomerase, flavanone 3-hydroxylase, di-hydroflavonol 4-reductase, and anthocyanidin synthase in the anthocyanin biosynthetic pathway. Genes involved in JA biosynthesis and key regulatory genes in the JA signaling pathway were significantly up-regulated, indicating that the JA signaling pathway may play an important regulatory role in the synthesis of anthocyanins in N. atrans. Conclusions: This study unravels the metabolic and molecular underpinnings of flower color transition in N. atrans, thereby establishing a theoretical basis for the targeted regulation of floral pigmentation and molecular breeding of ornamental water lilies. Full article

Proanthocyanidins (PAs) display antioxidant properties and can partially delay pericarp browning in postharvested litchi (Litchi chinensis Sonn.) fruits. In this study, litchi fruit was treated with 3 g/L PA and then stored at 25 °C for 10 days. Differential metabolites and differentially expressed genes were comprehensively analyzed in litchi pericarp across four stages of browning progression. A total of 630 metabolites were identified through untargeted metabolomic analysis, with 237 of them being annotated in the kyoto encyclopedia of genes and genomes (KEGG) database. The abundance of flavonoids (kaempferol), six types of anthocyanins, cyanidins, (−)-epicatechin, and (+)-catechin in the PA biosynthetic pathway was notably reduced in PA-treated pericarp compared to that of the control fruit. Transcriptomic analysis also revealed that five genes in the phenylpropanoid biosynthesis pathways and seven genes of phenoloxidase were significantly downregulated. In addition, correlation analysis revealed significant positive correlations between the browning index and genes like LcFLS (flavonol synthase), LcANS (anthocyanidin synthase), LcUFGT (UDP-glucose:anthocyanidin 3-O-glucosyltransferase), LcPPO (polyphenol oxidase), and LcLAC7 (laccase), and a significant negative correlation with PAs and (−)-epicatechin. In conclusion, PA treatment can efficiently delay pericarp browning, mainly by reducing brown substrate accumulation and oxidation, and decreasing PA oxidation and polymerization. This study delves into the regulatory mechanisms through which PA delays litchi pericarp browning. 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

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

In this study, red–blue light (7R3B) was used as the control (CK), while far-red (FR) and ultraviolet-A (UVA) light were supplemented to evaluate their effects on basil growth. The results showed that the FR treatment promoted plant height, stem diameter, and biomass, but reduced chlorophyll and carotenoid content, while the UVA treatment increased stem diameter and chlorophyll b content. Meanwhile, transcriptomic and metabolomic analyses were employed to examine changes in gene expression and metabolite accumulation in basil. The FR treatment reduced the levels of differentially accumulated metabolites (DAMs) in the carotenoid biosynthesis pathway, potentially contributing to the observed decrease in chlorophyll. The FR treatment upregulated the levels of five DAMs (gibberellin, cytokinin, brassinosteroid, jasmonic acid, and salicylic acid) and altered the differentially expressed genes (DEGs) such as gibberellin receptor (GID1) and jasmonate ZIM domain-containing protein (JAZ) in the plant hormone signal transduction pathway, thereby promoting plant growth and shade avoidance responses. The UVA treatment upregulated the 9-cis-epoxycarotenoid dioxygenase (NCED) expression in the carotenoid biosynthesis pathway, possibly indirectly promoting flavonoid synthesis. In the flavonoid biosynthesis pathway, the UVA treatment also promoted flavonoid accumulation by upregulating DEGs including flavonol synthase (FLS), anthocyanidin synthase (ANS), 5-O-(4-coumaroyl)-D-quinate 3′-monooxygenase (CYP98A), and flavanone 7-O-glucoside 2″-O-beta-L-rhamnosyltransferase (C12RT1), as well as increasing the levels of DAMs such as kaempferol, luteolin, apigenin, and leucopelargonidin. The accumulation of flavonoids improved antioxidant capacity and nutritional value in basil. Through a Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, this study provided valuable insights into the molecular and metabolic mechanisms of the FR and UVA regulation of basil growth, providing guidance for optimizing supplementary lighting strategies in plant factories. 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

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

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

Elevated levels of reactive oxygen species (ROS) are caused by ultraviolet B radiation (UV-B) stress. In response, plants strengthen their cell membranes, impeding photosynthesis. Additionally, UV-B stress initiates oxidative stress within the antioxidant defense system and alters secondary metabolism, particularly by increasing the quantity of UV-absorbing compounds such as flavonoids. The v-myb avian myeloblastosis viral oncogene homolog (MYB) transcription factor (TF) may participate in a plant’s response to UV-B damage through its regulation of flavonoid biosynthesis. In this study, we discovered that the photosynthetic activity of Rhododendron chrysanthum Pall. (R. chrysanthum) decreased when assessing parameters of chlorophyll (PSII) fluorescence parameters under UV-B stress. Concurrently, antioxidant system enzyme expression increased under UV-B exposure. A multi-omics data analysis revealed that acetylation at the K68 site of the RcTRP5 (telomeric repeat binding protein of Rhododendron chrysanthum Pall.) transcription factor was upregulated. This acetylation modification of RcTRP5 activates the antioxidant enzyme system, leading to elevated expression levels of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT). Upregulation is also observed at the K95 site of the chalcone isomerase (CHI) enzyme and the K178 site of the anthocyanidin synthase (ANS) enzyme. We hypothesize that RcTRP5 influences acetylation modifications of CHI and ANS in flavonoid biosynthesis, thereby indirectly regulating flavonoid production. This study demonstrates that R. chrysanthum can be protected from UV-B stress by accumulating flavonoids. This could serve as a useful strategy for enhancing the plant’s flavonoid content and provide a valuable reference for research on the metabolic regulation mechanisms of other secondary substances. Full article

Blueberries (Vaccinium spp.) are extremely sensitive to drought stress. Flavonoids are crucial secondary metabolites that possess the ability to withstand drought stress. Therefore, improving the drought resistance of blueberries by increasing the flavonoid content is crucial for the development of the blueberry industry. To explore the underlying molecular mechanism of blueberry in adaptation to drought stress, we performed an integrated analysis of the metabolome and transcriptome of blueberry leaves under drought stress. We found that the most enriched drought-responsive genes are mainly involved in flavonoid biosynthesis and plant hormone signal transduction pathways based on transcriptome data and the main drought-responsive metabolites come from the flavonoid class based on metabolome data. The UDP-glucose flavonoid 3-O-glucosyl transferase (UFGT), flavonol synthase (FLS), and anthocyanidin reductase (ANR-2) genes may be the key genes for the accumulation of anthocyanins, flavonols, and flavans in response to drought stress in blueberry leaves, respectively. Delphinidin 3-glucoside and delphinidin-3-O-glucoside chloride may be the most important drought-responsive flavonoid metabolites. VcMYB1, VcMYBPA1, MYBPA1.2, and MYBPA2.1 might be responsible for drought-induced flavonoid biosynthesis and VcMYB14, MYB14, MYB102, and MYB108 may be responsible for blueberry leaf drought tolerance. ABA responsive elements binding factor (ABF) genes, MYB genes, bHLH genes, and flavonoid biosynthetic genes might form a regulatory network to regulate drought-induced accumulation of flavonoid metabolites in blueberry leaves. Our study provides a useful reference for breeding drought-resistant blueberry varieties. Full article

Waxy corn is a special type of maize primarily consumed as a fresh vegetable by humans. Nitrogen (N) plays an essential role in regulating the growth progression, maturation, yield, and quality of waxy maize. A reasonable N application rate is vital for boosting the accumulation of both N and carbon (C) in the grains, thereby synergistically enhancing the grain quality. However, the impact of varying N levels on the dynamic changes in N metabolism, carbohydrate formation, and anthocyanin synthesis in purple waxy corn kernels, as well as the regulatory relationships among these processes, remains unclear. To explore the effects of varying N application rates on the N metabolism, carbohydrate formation, and anthocyanin synthesis in kernels during grain filling, a two-year field experiment was carried out using the purple waxy maize variety Jinnuo20 (JN20). This study examined the different N levels, specifically 0 (N0), 120 (N1), 240 (N2), and 360 (N3) kg N ha⁻¹. The results of the analysis revealed that, for nearly all traits measured, the N application rate of N2 was the most suitable. Compared to the N0 treatment, the accumulation and content of anthocyanins, total nitrogen, soluble sugars, amylopectin, and C/N ratio in grains increased by an average of 35.62%, 11.49%, 12.84%, 23.74%, 13.00%, and 1.87% under N2 treatment over five filling stages within two years, respectively, while the harmful compound nitrite content only increased by an average of 30.2%. Correspondingly, the activities of related enzymes also significantly increased and were maintained under N2 treatment compared to N0 treatment. Regression and correlation analysis results revealed that the amount of anthocyanin accumulation was highly positively correlated with the activities of phenylalanine ammonia-lyase (PAL) and flavanone 3-hydroxylase (F3H), but negatively correlated with anthocyanidin synthase (ANS) and UDP-glycose: flavonoid-3-O-glycosyltransferase (UFGT) activity, nitrate reductase (NR), and glutamine synthetase (GS) showed significant positive correlations with the total nitrogen content and lysine content, and a significant negative correlation with nitrite, while soluble sugars were negatively with ADP-glucose pyrophosphorylase (AGPase) activity, and amylopectin content was positively correlated with the activities of soluble starch synthase (SSS), starch branching enzyme (SBE), and starch debranching enzyme (SDBE), respectively. Furthermore, there were positive or negative correlations among the detected traits. Hence, a reasonable N application rate improves purple waxy corn kernel nutritional quality by regulating N metabolism, as well as carbohydrate and anthocyanin biosynthesis. Full article