Phenolic Biosynthesis Research Articles

LED light improves shoot multiplication, steviol glycosides and phenolic compounds biosynthesis in Stevia rebaudiana Bertoni in vitro culture

Light-emitting diode (LED) lamps are efficient elicitors of secondary metabolites. To investigate the influence of LED light on steviol glycosides (SGs) and phenolic compounds biosynthesis, stevia shoots were cultured under the following LED lights: white–WL, blue–B, red–R, 70% red and 30% blue–RB, 50% UV, 35% red and 15% blue–RBUV, 50% green, 35% red and 15% blue–RBG, 50% yellow, 35% red and 15% blue–RBY, 50% far-red, 35% red and 15% blue–RBFR and white fluorescent light (WFl, control). RBG light stimulated shoots’ biomass production. RBFR had a beneficial impact on stevioside biosynthesis (1.62 mg/g dry weight, DW), while RBUV favoured the production of rebaudioside A (3.15 mg/g DW). Neochlorogenic, chlorogenic, caffeic, 4-feruloylquinic, isochlorogenic A, rosmarinic acids and the flavonoid quercitrin were identified in the obtained material. A stimulatory effect of RBFR and RBUV on the biosynthesis of phenolic compounds was noted. LED light also influenced stomata appearance, stomata density, photosynthetic pigments, soluble sugar content and antioxidant enzyme activities in stevia shoots. This is the first report to provide evidence of the stimulating effect of LED light on biomass yield, SGs production and phenolic compounds in stevia shoot cultures.

Phenolic compounds of Rumex acetosella L. collected from two different regions of Iğdır province (Türkiye)

This investigation examines the phenolic profile of Rumex acetosella L. harvested from two disparate locales within Iğdır Province, Türkiye, aimed at evaluating the impact of different locations on phenolic compounds. Employing High-Performance Liquid Chromatography (HPLC), a total of 19 phenolic constituents, including chlorogenic acid, caffeic acid, rutin, and naringin, were both identified and quantified. Crucial regional variations were identified, with Hoşhaber presenting higher levels of chlorogenic acid, rutin, and naringin in comparison to Karakuyu. However, caffeic acid was found to be more prevalent in the Karakuyu region. Certain compounds, notably vanillin and p-coumaric acid, were exclusively identified in Hoşhaber. These results substantiate the premise that environmental determinants, encompassing soil composition and climatic conditions, significantly influence phenolic biosynthesis.

Foliar Nutrition Strategies for Enhancing Phenolic and Amino Acid Content in Olive Leaves.

Studies on selenium (Se) and silicon (Si) foliar biostimulation of different plants have been shown to affect concentrations of phenolic compounds. However, their effects on olive (Olea europaea L.) primary and secondary metabolites have not been fully investigated. Therefore, the effects of foliar sprayed Si and Se and their combination on the concentration of phenols, selected metabolites involved in the phenol biosynthesis, and mineral elements concentrations were determined in olive leaves of the field-grown cultivar Leccino. During the summer period, leaves were foliar sprayed three times, after which were sampled 30 days after the corresponding application. In general, foliar treatment of Si or Se increased the concentrations of several predominant phenolic compounds, such as oleuropein, oleacein, and specific flavonoids. The effects were especially pronounced after the third application in the harvest time sampling time. Amino acids and other phenol precursors were also significantly affected. The effects were phenol-specific and depended on the treatment, sampling time, and treatment × sampling time interaction. The response of verbascoside to the applied treatments appeared to be closely linked to corresponding changes in its amino acid precursors, such as tyrosine, while its connection with tryptophan and IAA has to be cautiously considered. In contrast, for other phenolic compounds like secoiridoids, a clear interdependence with their precursors was not identified, likely due to the more complex nature of their biosynthesis. The effects on the concentrations of elements other than Se and Si were milder.

Influencia de nanopartículas de potasio en el rendimiento y compuestos bioactivos de frutos de melón

Potassium is known as a quality element due to its key role in sugar transport, metabolite biosynthesis, and enzyme activation. This study aimed to determine the optimal dose of potassium nanoparticles (K NPs) in melon plants and evaluate their impact on yield, nutraceutical quality, and K content in the fruits. A field experiment was conducted with melon cv Cruiser, applying four foliar doses of K NPs (100, 200, 300, and 400 mg L⁻¹) and a control treatment (distilled water). The results indicated that foliar application of K NPs significantly affected the nutraceutical quality and K content in melon fruits without impacting crop yield. Melon fruits from plants treated with the intermediate dose (200 mg L⁻¹) showed the highest levels of total soluble solids and firmness. The low dose (100 mg L⁻¹) increased the biosynthesis of flavonoids, total phenols, and antioxidant capacity, while higher doses (300 and 400 mg L⁻¹) reduced bioactive compounds, although they increased the potassium content in the fruits. Foliar application of K NPs is a viable strategy that, when integrated with agronomic practices, can improve the nutraceutical quality of melons without compromising crop yield. However, it is essential to determine the appropriate doses, as low and intermediate doses enhance the fruit's biophysical and nutraceutical quality, while higher doses may have adverse effects on bioactive compounds.

Gibberellin-Induced Transcription Factor SmMYB71 Negatively Regulates Salvianolic Acid Biosynthesis in Salvia miltiorrhiza.

Salvia miltiorrhiza, the valuable traditional Chinese medicinal plant, has been used in clinics for thousands of years. The water-soluble salvianolic acid compounds are bioactive substances used in treating many diseases. Gibberellins (GAs) are growth-promoting phytohormones that regulate plant growth and development. Previous studies have demonstrated that GAs can promote salvianolic acid accumulation in S. miltiorrhiza; however, the underlying mechanism requires further investigation. Here, we identified a GA-induced R2R3MYB transcription factor (TF), SmMYB71, from a transcriptome library of GA-treated S. miltiorrhiza. SmMYB71 was highly expressed in the root of S. miltiorrhiza and localized to the nucleus. SmMYB71-knockout hairy roots showed higher salvianolic acid accumulation compared to wild lines. Overexpressing SmMYB71 in S. miltiorrhiza hairy roots significantly decreased the content of salvianolic acid by downregulating key salvianolic acid biosynthesis enzymes such as SmRAS and SmCYP98A14. The GCC box in the promoter of SmMYB71 can bind with SmERF115, suggesting that SmMYB71 is regulated by SmERF115 in salvianolic acid biosynthesis. These findings demonstrate a novel regulatory role of SmMYB71 in GA-mediated phenolic acid biosynthesis. With the development of CRISPR/Cas9-based genome editing technology, the SmMYB71 regulation mechanism of salvianolic acid biosynthesis provides a potential target gene for metabolic engineering to increase the quality of S. miltiorrhiza.

Strigolactone modulates phenolic acid accumulation and thereby improves tolerance to UV-B stress in Rhododendron chrysanthum Pall.

Multi-omics studies have shown that strigolactone modulates phenolic acid accumulation in the leaves of R. chrysanthum and can enable it to cope with UV-B stress. UV-B stress is an abiotic stress that plants will inevitably suffer during growth and can seriously affect the normal physiological state of plants. Strigolactone, a phytohormone, has been less studied and it is important to investigate its regulation of plant growth under UV-B radiation. In the present study, we investigated the changes in leaves of Rhododendron chrysanthum Pall. (R. chrysanthum) under UV-B radiation. The leaves of R. chrysanthum were collected for widely targeted metabolomics, hormonomics, transcriptomics, proteomics and acetylated proteomics assays. The results showed that the leaves of R. chrysanthum were able to produce a large amount of differential phenolic acids with antioxidant effects under UV-B stress, the content of strigolactone was significantly elevated, and the genes and proteins involved in phenolic acid biosynthesis and strigolactone biosynthesis were significantly altered, and some of the proteins (ASP1, 4CLL7, and CCD1) underwent acetylation modification. Meanwhile, correlation analysis showed that strigolactone was strongly correlated with differential phenolic acids, which might regulate the adaptive responses of the R. chrysanthum under UV-B stress. In this paper, we investigated the effects of strigolactone on the accumulation of phenolic acid compounds and found a strong correlation between strigolactone and elevated phenolic acid levels, which provided insights into the molecular mechanism of plant regulation of phenolic acid accumulation, and facilitated the adoption of measures to mitigate the adverse effects of UV-B stress on plant growth, and to achieve the purpose of protecting plant germplasm resources.

Investigating the action model of the resistance enhancement induced by bacterial volatile organic compounds against Botrytis cinerea in tomato fruit.

Inducing natural resistance against pathogen infection in postharvest tomatoes is a sustainable strategy for reducing postharvest losses. The action model underlying the resistance enhancement of tomatoes induced by bacterial volatile organic compounds (VOCs) against Botrytis cinerea, however, have not been explored. In this study, RNA-seq, metabolomics and physiological analysis were used to evaluate global change of defense response induced by VOCs in tomatoes. The application of VOCs inhibited the damage to tomatoes caused by B.cinerea. VOCs treatment had remarkable beneficial effects on the activities of the main defence-related enzymes, including chitinases, glucanases, peroxidases, ascorbate peroxidases, polyphenol oxidases, and phenylalanine ammonia-lyases. The expression of response genes involved in salicylic acid and jasmonic acid biosynthesis and signalling pathways was enhanced upon VOCs treatment. Metabolomics data demonstrated that VOC treatment triggered the accumulation of phenolic acids, including substrates in phenolic acid biosynthesis pathways, hydroxycinnamic acid, hydroxybenzoic acid, and their derivatives. Transcriptomics analysis and qRT-PCR verification revealed that VOCs treatment significantly upregulates the expression of core genes related to phenolic acid biosynthesis, specifically in shikimate pathway (SlDAHPS, SlSDH, SlCS, and SlADT3) and phenylalanine metabolic pathway (SlPAL, Sl4CL, SlBAHD1, SlCYP98A2 and SlCAP84A1). Results confirmed that VOCs enhanced tomatoes postharvest resistance against B. cinerea by regulating defence enzyme activity, SA/JA signalling, and phenolic acid biosynthesis pathway. This study provides new insights into the mechanisms by which VOCs fumigation manages postharvest grey mould in tomatoes.

Effect of elevated ammonium on biotic and abiotic stress defense responses and expression of related genes in cucumber (Cucumis sativus L.) plants

Ammonium (NH4+) enhances plant defense mechanisms but can be phytotoxic as the sole nitrogen source. To investigate the impact of a balanced NH4+ and NO3− ratio on plant defense parameters without adverse effects, cucumber plants (Cucumis sativus L.) were grown under control (14 mM NO3− + 2 mM NH4+) and elevated level of NH4+ (eNH4+, 8 mM NO3−+ 8 mM NH4+). Plants subjected to eNH4+ showed significantly increased shoot and root biomass by about 41% and 47%, respectively. Among the antioxidant enzymes studied, ascorbate peroxidase (EC 1.11.1.11) activity was increased up to 3.3 fold in eNH4+ compared with control plants, which was associated with enhanced resistance to paraquat. Upregulation of PATHOGENESIS RELATED PROTEIN 4 (PR4) and LIPOXYGENASE 1 (LOX1), accompanied by increased concentrations of salicylic acid and nitric oxide, conferred more excellent resistance of eNH4+ plants to powdery mildew infection. However, the expression levels of ACC OXIDASE 1 (ACO1) and RESPIRATORY BURST OXIDASE HOMOLOGS B (RBOHB) were lower in eNH4+ plants, which was consistent with decreased NADPH oxidase activity and lower leaf H2O2 levels. The biosynthesis of phenolics was enhanced, whereas the activities of polymerizing enzymes and lignin deposition were reduced by half in eNH4+ plants. Besides, a significant effect on plant biomass under salt or drought stress has not been observed between control and eNH4+ plants. These results showed that different defense pathways are distinctively affected by eNH4+ treatment, and the NH4+ to NO3− ratio may play a role in fine-tuning the plant defense response.

Metabolomic and transcriptomic analyses reveal the regulation mechanism of postharvest light-induced phenolics accumulation in mango peel

Phenolics are important secondary metabolites and antioxidants in plants. Mango fruit accumulate abundant phenolic compounds, while the effect of light on the accumulation of different phenolic components in mango peel and the relevant molecular mechanism are still unknown. In this study, mature ‘Guifei’ mango fruit was subjected to postharvest UV-B/white light treatment, fruit peel was sampled for metabolomic and transcriptomic analyses. The results showed that light induced the accumulation of anthocyanins, flavonoids, and phenolics, thus increasing the antioxidant capacity in mango peel. A total of 1223 phenolic metabolites were detected in mango peel, 36 phenolic compounds were defined as key differentially accumulated metabolites (DAMs) regulated by light. Among the DAMs, the accumulation of 33 compounds was promoted by light, and 30 of these were flavonoids. Light up-regulated most phenolics biosynthesis and light signaling pathway genes and also regulated expression of plant hormone signaling pathway genes. Transcription factors (TFs) such as MYB, C2H2 and HSF were identified as candidates regulating phenolics biosynthesis in mango. Our findings not only provide information for commercial application of light in promoting mango fruit appearance and increasing phenolics content and antioxidant capacity, but also reveal important aspects of the molecular regulation of light-induced phenolics accumulation in mango peel.

Effect of Ag+ and Cd2+ Elicitation on Polyphenol Production in Shoot Culture of Dracocephalum ruyschiana L.

Abiotic elicitation with heavy metals has demonstrated considerable potential to stimulate the production of industrially important secondary metabolites in plant in vitro cultures. The present study investigates the effect of exogenous silver nitrate and cadmium chloride supplementation on flavonoid and phenolic acid production, as well as other indicators of oxidative stress, in shoot cultures of Dracocephalum ruyschiana L. Owing to the presence of bioactive polyphenolic compounds, this Mongolian medicinal plant is traditionally used as an anti-inflammatory, antibacterial and antipyretic agent. The shoots were cultured for three weeks, and then, cadmium (Cd2+) and silver (Ag+) ions (50 or 100 µM) were added to the medium. The maximum proliferation rate was observed in the presence of 100 µM Ag+ (almost 5), the highest chlorophyll content in the presence of 100 µM Cd2+ (0.6 mg/g FW) and the highest biomass was observed with both these treatments (73.4-75.7 g FW and 7.53-7.72 g DW). UPLC-PDA-ESI-MS analysis revealed four phenolic acids and five flavonoid derivatives in the hydromethanolic extract of D. ruyschiana shoots. All treatments stimulated the production of rosmarinic acid (RA), which was the dominant compound in the analyzed culture; the highest level of RA, i.e., about three times higher than the control, was noted in shoots exposed to 50 µM Cd2+ (14.72 mg/g DW), whereas the level of most flavonoids in the culture increased most significantly when exposed to Cd2+ at a concentration of 100 µM. Moreover, the shoots grown in the presence of 100 µM Cd2+ exhibited significantly higher antioxidant potential in comparison to the control. Our findings indicate that heavy metals are able to stimulate phenolic compound biosynthesis in Dracocephalum shoots without any negative impact on their growth. These results could be of significant importance for the medical, nutraceutical and agronomic industries.

Heterologous Expression of MYB Gene (Rosea1) or bHLH Gene (Delila) from Antirrhinum Increases the Phenolics Pools in Salvia miltiorrhiza.

Phenolic acids have health-promoting properties, however, but their low concentrations in Salvia miltiorrhiza limit broader medicinal applications. MYB and bHLH transcription factors activate multiple target genes involved in phenylpropanoid metabolism, thereby enhancing the production of various secondary metabolites. We introduced the MYB transcription factor Antirrhinum Rosea1 (AmROS1) or Delila (AmDEL) into S. miltiorrhiza and observed that antioxidant activity in transgenic plants increased by 1.40 to 1.80-fold. The total content was significantly higher in transformants compared to the controls. Furthermore, heterologous expression of AmROS1 or AmDEL triggered moderate accumulations of rosmarinic acid and salvianolic acid at various growth stages. Levels of total phenolics, total flavonoids, and anthocyanins were significantly elevated. These biological and phytochemical alterations were correlated with the upregulated expression of genes involved in phenolic acid biosynthesis. Our findings demonstrate that AmROS1 and AmDEL function as a transcriptional activator in phenolic acids biosynthesis. This study offers further insights into the heterologous or homologous regulation of phenolics production, potentially enabling its engineering in S. miltiorrhiza.

Biomass and Phenolic Acid Accumulation in Salvia austriaca Hairy Roots Grown in Temporary Immersion and Mist-Trickling Bioreactors

Transformed roots of Salvia austriaca were cultivated for 45 days in various systems, including Erlenmeyer flasks, a temporary immersion system (TIS) bioreactor, and a mist-trickling bioreactor, under controlled light conditions. The mist-trickling bioreactor yielded the highest biomass, with fresh and dry weights of 155.4 g/L and 10.2 g/L, respectively. Quantitative UHPLC analysis of hydromethanolic extracts revealed the biosynthesis of significant phenolic acids: caffeic acid, rosmarinic acid, and salvianolic acid A. Among these, rosmarinic acid was the most abundant, with its concentration varying based on the cultivation system. The highest total phenolic acid content, 165 mg/L, was obtained in the mist-trickling bioreactor, demonstrating its superiority in both biomass production and phenolic acid biosynthesis. This study highlights the potential of mist-trickling bioreactors for optimizing growth and metabolite production in S. austriaca transformed root cultures.

Genome-Wide Identification of UGT Genes and Analysis of Their Expression Profiles During Fruit Development in Walnut (Juglans regia L.)

Walnut (Juglans regia L.) possesses the ability to prevent coronary heart disease and promote cardiovascular health. This ability can be attributed to their rich content of polyphenols, particularly flavonoids. The biosynthesis of flavonoids is reliant on the catalytic activity of uridine diphosphate glycosyltransferase (UGT). However, the identification of UGTs in walnut has not been reported. In the current study, a total of 124 UGT genes containing the PSPG box were identified from the walnut genome. Based on phylogenetic analysis, the 124 UGTs could be classified into 16 distinct groups, which exhibited an uneven distribution across the 16 chromosomes. Subcellular localization prediction analysis revealed that approximately 78.23% of walnut UGT proteins were predominantly localized in the cytoplasmic compartment. Furthermore, motif annotation confirmed that motifs 1, 2, and 3 represented conserved structural features within UGT proteins, while interestingly, around 56.5% of walnut UGT members lacked introns. Through the analysis of promoter cis-regulatory elements, it was revealed that JrUGTs are involved in photoresponse, hormonal regulation, and other physiological responses. In conjunction with transcriptome analysis and quantitative expression, approximately 39% of UGT genes in walnut exhibited high expression levels during early fruit development. Correlation analysis between UGT genes’ expression and phenolic content in walnut indicated that JrUGT6, JrUGT38, JrUGT39, JrUGT58, JrUGT69, JrUGT75, and JrUGT82 might be involved in phenolic biosynthesis in walnut. This comprehensive study provides an overview of the UGT genes in walnut, serving as a valuable reference and theoretical foundation for further investigations into the biological functions of JrUGTs in flavonoid biosynthesis.

NaCl Stress Stimulates Phenolics Biosynthesis and Antioxidant System Enhancement of Quinoa Germinated after Magnetic Field Pretreatment.

Our previous study showed that magnetic field pretreatment promoted germination and phenolic enrichment in quinoa. In this study, we further investigated the effects of NaCl stress on the growth and phenolic synthesis of germinated quinoa after magnetic field pretreatment (MGQ). The results showed that NaCl stress inhibited the growth of MGQ, reduced the moisture content and weight of a single plant, but increased the fresh/dry weight. The higher the NaCl concentration, the more obvious the inhibition effect. In addition, NaCl stress inhibited the hydrolysis of MGQ starch, protein, and fat but increased the ash content. Moreover, lower concentrations (50 and 100 mM) of NaCl stress increased the content of MGQ flavonoids and other phenolic compounds. This was due to the fact that NaCl stress further increased the enzyme activities of PAL, C4H, 4CL, CHS, CHI, and CHR and up-regulated the gene expression of the above enzymes. NaCl stress at 50 and 100 mM increased the DPPH and ABTS scavenging capacity of MGQ and increased the activities of antioxidant enzymes, including SOD, POD, CAT, APX, and GSH-Px, further enhancing the antioxidant system. Furthermore, principal component analysis showed that NaCl stress at 100 mM had the greatest combined effect on MGQ. Taken together, NaCl stress inhibited the growth of MGQ, but appropriate concentrations of NaCl stress, especially 100 mM, helped to further increase the phenolic content of MGQ and enhance its antioxidant system.

Exogenous p-coumaric acid treatment improves phenolic compounds biosynthesis of postharvest cherry tomatoes by regulating physiological metabolism.

To investigate the effect of p-coumaric acid (p-CA) on postharvest cherry tomatoes, breaker stage fruits were treated with p-CA to analyze the physiological metabolism during storage. The results showed that exogenous p-CA treatment improved the sensory quality of tomato fruits. Transcriptomics results indicated that 782 genes (339 up-regulated and 443 down-regulated) were differentially expressed between p-CA treated and control fruits. Results suggested that p-CA treatment regulated the synthesis of phenolic compounds and inhibited the fruit ripening through the pathways of mangiferic acid biosynthesis and phenylalanine metabolism. Key enzymes activities of the phenylpropane metabolic pathway of tomato fruits were increased, including phenylalanine ammonia lyase (PAL), cinnamic acid 4-hydroxylase (C4H), and 4-coumarate-CoA ligase (4CL). In addition, the total phenols content, flavonoids content and antioxidant capacities of tomato fruits were improved with p-CA treatment. Overall, these findings showed that p-CA treatment could be a potential strategy for fruit and vegetable preservation.

Integrated transcriptomic and metabolomic analyses reveal transcriptional regulatory network for phenolic acid biosynthesis in potato tubers

The phenolic acid profile and concentration in potatoes signify their nutritional significance and functional value. In this study, a total of 398 metabolites, including 52 phenolic acids, were identified from three colored potato clones at three developmental stages using widely targeted metabolomics. Red and purple-fleshed potatoes exhibit higher levels of most phenolic acids compared to yellow-fleshed potatoes, particularly notable in their chlorogenic acid content. We concentrated on the distribution of differentially expressed transcription factors (TFs) among these clones, pinpointing the ERF (ethylene response factor), bHLH (basic helix-loop-helix), and MYB (myeloblastosis) as the predominant TFs via RNA-Seq analysis. Based on integrated transcriptomic and widely targeted metabolomic analysis, 23 pathway genes that might be involved in the biosynthesis of phenolic acid were identified. Furthermore, three central modules and several hub genes, encompassing 7 TFs, were identified. Notably, bHLH1 was identified as a key transcriptional regulator within this network, specifically activating the transcription of StCCoAOMT, a key enzyme catalyzing the methylation of caffeoyl-CoA to feruloyl-CoA. This study may provide new insights into the molecular mechanisms of phenolic acid biosynthesis in potatoes and potentially advances the development of functional food products derived from these potatoes.

Salicylic acid functionalized chitosan nanocomposite increases bioactive components and insect resistance of Agastache rugosa

The abundance of monoterpenoids and phenolic compounds determines the medicinal quality and anti-insect properties of Agastache rugosa, which can be compromised by biotic stress such as herbivore attacks. The traditional use of chemical pesticides to mitigate herbivore interference is increasingly incompatible with sustainable agriculture. In response, nanotechnology-based biostimulants, which can activate metabolic processes to enhance plant growth and stress resistance, offer a more cost-effective and environmentally-friendly alternative. However, to date, it remains unknown how nano-biostimulants improve the therapeutic value and insect resistance of medicinal plants simultaneously. This study investigates the effect of 0–1000 mg/L of a nano-biostimulant salicylic acid functionalized chitosan nanocomposite (SCN) on the pharmacological and anti-herbivore properties of medicinal plant A. rugosa. Results showed that 100 mg/L SCN significantly inhibited Spodoptera litura growth by 62.9 %, and increased plant shoot and root biomass by 107.2 % and 77.6 %, respectively. Moreover, 100 mg/L SCN significantly upregulated the expression of the key genes (e.g., LS, L3OH, and CHS) involved in monoterpene and phenolic compounds biosynthesis by 1.4–10.1 folds, thus boosting the production of active compounds such as pulegone, β-myrcene, and chlorogenic acid by 1.5–24.4 folds. These enhancements were superior to salicylic acid or chitosan alone. Altogether, our findings promote the sustainable and eco-friendly application of nano-biostimulant in improving the quality of medicinal plants and green pest control in agroecosystems.

The ERF transcription factor SlERF7 promotes UV-C-induced biosynthesis of phenolic compounds in tomato

In this study, the molecular pathways of SlERF7 in regulating the synthesis and accumulation of phenolic compounds induced by postharvest UV-C in tomato fruit was deeply investigated by constructing transgenic plants. The findings revealed a pronounced induction of phenolic compounds accumulation following UV-C irradiation, coupled with heightened activities of PAL, 4CL, C4H, CHS, and CHI enzymes, alongside upregulated expression levels of SlPAL5, SlC4H, Sl4CL, SlCHS2, and SlCHI within SlERF7 overexpressed fruit. Conversely, SlERF7 knockout fruit exhibited diminished levels of phenolic compounds, enzyme activities, and gene expression after UV-C irradiation. Furthermore, subcellular localization analysis showed that SlERF7 was localized in the nucleus. Dual luciferase assay and electrophoretic mobility shift assay (EMSA) indicated that SlERF7 directly bound to the GCC-box in the SlPAL5 promoter and activated its transcriptional activity. Therefore, it was confirmed that SlERF7 might positively promote UV-C-induced phenolic biosynthesis in postharvest tomato fruit by targeting the promoter of SlPAL5.

Production of High-Quality Wheat Sprouts of Strong Antioxidant Capacity: Process Optimization and Regulation Mechanism of Red Light Treatment.

Light treatment is an innovative method to enhance the synthesis of secondary metabolites in plants and improve the quality of plant-based food ingredients. This study investigated the effects of red light treatment on the physiological and biochemical changes during wheat germination, aiming to produce high-quality wheat sprouts with strong antioxidant capacity. Using response surface methodology, the study optimized the conditions for phenolic accumulation in wheat sprouts under red light treatment and explored the molecular mechanisms behind the enhancement of total phenolic content (TPC) and quality. The results indicated that red light treatment significantly increased the TPC in wheat sprouts. The highest TPC, reaching 186.61 μg GAE/sprout, was observed when wheat sprouts were exposed to red light at an intensity of 412 μmol/m²/s for 18.2 h/d over four days. Compared to no light, red light treatment significantly increased the content of photosynthetic pigments (chlorophyll and carotenoids). Red light treatment notably heightened the levels of both free and bound phenolic in the germinating wheat. Red light treatment markedly boosted the activities and relative gene expression levels of enzymes related to phenolic biosynthesis, including phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, and 4-coumarate-CoA ligase. Additionally, red light treatment enhanced the antioxidant capacity of wheat sprouts by improving the activity and gene expression of four key antioxidant enzymes, thereby promoting growth and germination. This research suggested that red light treatment is an effective strategy for stimulating total phenolic biosynthesis, enhancing antioxidant capacity, and producing highly nutritious wheat sprouts, thus laying the groundwork for developing total phenolic-enriched wheat sprouts as valuable food ingredients in the future.

Alteration of nutrient uptake and secondary metabolism connection by foliar application of citrus flavonoids to broccoli plants

The nutritional value of broccoli is largely attributed to its abundant secondary metabolites such as phenolic compounds and glucosinolates (GSLs). However, the dynamic relationship between these compounds, including potential synergistic or antagonistic interactions that influence plant physiology and metabolism, remains unclear. In this study, we aimed to elucidate the intricate interplay between phenolic compounds and GSLs in broccoli plants and their consequent effects on primary metabolism and regulatory mechanisms governing water and nutrient uptake. To investigate this, we externally supplied citric phenolic compounds to broccoli plants, and then measured the levels of GSLs and phenolic compounds, along with assessing physiological parameters such as biomass, gas exchange, and nutrient content. Additionally, the expression of genes related to GSLs and phenolics biosynthesis, as well as genes involved in water transport were measured. Our results revealed a complex interrelation between phenolic compounds and GSLs, with phenolic compounds significantly modulating the response of GSLs and influencing the expression of aquaporin genes. This modulation had notable effects on nutrient regulation mechanisms in broccoli plants. Overall, our findings shed light on the regulatory mechanisms underlying the interaction between phenolic compounds, GSLs and growth, providing insights into their roles in plant physiology and metabolism.