Accumulation Of Chlorogenic Acid Research Articles

Analysis of varietal advantages of leaf form <i>Apium graveolens</i> L. according to chlorogenic acid content

Introduction. Special studies on the benefits of agricultural crops – current research regarding the prospects for the development of their products based on functional and specialized nutrition. Substances with a phenolic profile carry out various types of pharmacological activity aimed at treating metabolic and other socially significant phenomena, which allows them to be positioned as generally accepted main ingredients. The leafy botanical form of celery is a rich source of phenolic compounds.Aim. Development and validation of a method for the quantitative analysis of chlorogenic acid to assess the varietal advantages of Apium graveolens L. raw materials using HPLC.Materials and methods. For the analysis, we used leaf celery grass of different varieties grown at two sites (the village of Lembolovo and SNT "Ruchey"). Sample preparation of raw materials was carried out by extraction in an ultrasonic bath. Chromatography conditions: column Luna 5 μm C 18(100) Å LC Column 250 × 4.6 mm, thermostat temperature 40 °C, detection wavelength 327 nm. PF A 0.05 % TFA, PF B acetonitrile. Elution mode: 0 min 12 % B, 20 min 30 % PF B, 23 min 12 % PF B.Results and discussion. According to the data obtained, the accumulation of chlorogenic acid in celery raw materials depends on both the plant variety and the cultivation conditions. However, the difference in the quantitative content of the target component correlates between varieties grown on different sites. The highest content of chlorogenic acid was noted in the variety Nezhny (SNT "Ruchey") and amounted to 0.464 ± 0.012. The variety Summer Boom can be distinguished as the best variety.Conclusion. The results of the study can be used in the development and quality control of functional and specialized nutrition based on the leafy botanical form of odorous celery due to the high content of phenolic substances.

Integrated transcriptomic and CGAs analysis revealed IbGLK1 is a key transcription factor for chlorogenic acid accumulation in sweetpotato (Ipomoea batatas [L.] Lam.) blades

Sweetpotato blades are rich in the functional secondary metabolite chlorogenic acid (CGA), which deepen potential for effective utilization of the blade in industry. In this study, we evaluated the type and content of CGA in the blades of 16 sweetpotato genotypes and analyzed the correlation between CGA content and antioxidant capacity. Then we isolated and characterized IbGLK1, a GARP-type transcription factor, by comparative transcriptome analysis. A subcellular localization assay indicated that IbGLK1 is located in the nucleus. Overexpression and silencing of IbGLK1 in sweetpotato blade resulted in a 0.90-fold increase and 1.84-fold decrease, respectively, in CGA content compared to the control. Yeast one-hybrid and dual-luciferase assays showed that IbGLK1 binds and activates the promoters of IbHCT, IbHQT, IbC4H, and IbUGCT, resulting in the promotion of CGA biosynthesis. In conclusion, our study provides insights into a high-quality gene for the regulation of CGA metabolism and germplasm resources for breeding sweetpotato.

Salicylic acid positively regulates maize defenses against lepidopteran insects

In response to insect attack, plants use intricate signaling pathways, including phytohormones, such as jasmonate (JA), ethylene (ET), and salicylic acid (SA), to activate defenses. Maize (Zea mays) is one of the most important staple food crops around the world. Previous studies have shown that the JA and ET signaling play important roles in maize defense against insects, but little is known about whether and how SA regulates maize resistance to insect herbivores. In this study, we ectopically expressed the NahG (salicylate hydroxylase) gene in maize plants (NahG maize) to block the accumulation of SA. It was found that compared with the wild-type (WT) maize, the NahG maize exhibited decreased resistance to the generalist insects Spodopteralitura and Spodoptera frugiperda and the specialist Mythimna separata, and the compromised resistance in the NahG maize was associated with decreased levels of defensive metabolites benzoxazinoids (Bxs) and chlorogenic acid (CA). Quantification of simulated S. litura feeding-induced JA, JA-isoleucine conjugate (JA-Ile), and ET in the WT and NahG maize indicated that SA does not regulate JA or JA-Ile, but positively controls ET. We provide evidence suggesting that the SA pathway does not crosstalk with the JA or the ET signaling in regulating the accumulation of Bxs and CA. Transcriptome analysis revealed that the bHLH, ERF, and WRKY transcription factors might be involved in SA-regulated defenses. This study uncovers a novel and important phytohormone pathway in maize defense against lepidopterous larvae.

Uncovering the Role of Hydroxycinnamoyl Transferase in Boosting Chlorogenic Acid Accumulation in Carthamus tinctorius Cells under Methyl Jasmonate Elicitation.

Chlorogenic acids (CGAs) are bioactive compounds widely used in the food, pharmaceutical, and cosmetic industries. Carthamus tinctorius is an important economic crop, and its suspension cells are rich in CGAs. However, little is known about the biosynthesis and regulation of CGAs in Carthamus tinctorius cells. This study first elucidated the regulatory mechanism of CGA biosynthesis in methyl jasmonate (MeJA)-treated Carthamus tinctorius cells and the role of the MeJA-responsive hydroxycinnamoyl transferase (HCT) gene in enhancing their CGA accumulation. Firstly, temporal changes in intracellular metabolites showed that MeJA increased the intracellular CGA content up to 1.61-fold to 100.23 mg·g-1. Meanwhile, 31 primary metabolites showed significant differences, with 6 precursors related to increasing CGA biosynthesis. Secondly, the transcriptome data revealed 3637 new genes previously unannotated in the Carthamus tinctorius genome and 3653 differentially expressed genes. The genes involved in the plant signaling pathway and the biosynthesis of CGAs and their precursors showed a general up-regulation, especially the HCT gene family, which ultimately promoted CGA biosynthesis. Thirdly, the expression of a newly annotated and MeJA-responsive HCT gene (CtHCT, CtNewGene_3476) was demonstrated to be positively correlated with CGA accumulation in the cells, and transient overexpression of CtHCT enhanced CGA accumulation in tobacco. Finally, in vitro catalysis kinetics and molecular docking simulations revealed the ability and mechanism of the CtHCT protein to bind to various substrates and catalyze the formation of four hydroxycinnamic esters, including CGAs. These findings strengthened our understanding of the regulatory mechanism of CGA biosynthesis, thereby providing theoretical support for the efficient production of CGAs.

Integrated metabolomics and transcriptomics analysis highlight key pathways involved in the somatic embryogenesis of Darjeeling tea.

Darjeeling tea is a globally renowned beverage, which faces numerous obstacles in sexual reproduction, such as self-incompatibility, poor seed germination, and viability, as well as issues with vegetative propagation. Somatic embryogenesis (SE) is a valuable method for rapid clonal propagation of Darjeeling tea. However, the metabolic regulatory mechanisms underlying SE in Darjeeling tea remain largely unknown. To address this, we conducted an integrated metabolomics and transcriptomics analysis of embryogenic callus (EC), globular embryo (GE), and heart-shaped embryo (HE). The integrated analyses showed that various genes and metabolites involved in the phenylpropanoid pathway, auxin biosynthesis pathway, gibberellin, brassinosteroid and amino acids biosynthesis pathways were differentially enriched in EC, GE, and HE. Our results revealed that despite highly up-regulated auxin biosynthesis genes YUC1, TAR1 and AAO1 in EC, endogenous indole-3-acetic acid (IAA) was significantly lower in EC than GE and HE. However, bioactive Gibberellin A4 displayed higher accumulation in EC. We also found higher BABY BOOM (BBM) and Leafy cotyledon1 (LEC1) gene expression in GE along with high accumulation of castasterone, a brassinosteroid. Total flavonoids and phenolics levels were elevated in GE and HE compared to EC, especially the phenolic compound chlorogenic acid was highly accumulated in GE. Integrated metabolome and transcriptome analysis revealed enriched metabolic pathways, including auxin biosynthesis and signal transduction, brassinosteroid, gibberellin, phenylpropanoid biosynthesis, amino acids metabolism, and transcription factors (TFs) during SE in Darjeeling tea. Notably, EC displayed lower endogenous IAA levels, conducive to maintaining differentiation, while higher IAA concentration in GE and HE was crucial for preserving embryo identity. Additionally, a negative correlation between bioactive gibberellin A4 (GA4) and IAA was observed, impacting callus growth in EC. The high accumulation of chlorogenic acid, a phenolic compound, might contribute to the low success rate in GE and HE formation in Darjeeling tea. TFs such as BBM1, LEC1, FUS3, LEA, WOX3, and WOX11 appeared to regulate gene expression, influencing SE in Darjeeling tea.

HPLC-MS/MS Profiles, Antioxidant, Neuroprotective, Antidiabetic and Skin Protective Effects of Different Extracts of Vicia peregrina L. Collected from the Eastern Region of Turkey.

Many Vicia species (Fabaceae) were proven to possess bioactive compounds with potential health beneficial properties. The present study was designed to determine the phenolic constituents, antioxidant and enzyme inhibition activities of aerial parts and seed of V. peregrina. Hexane, ethyl acetate and methanol extracts were prepared by maceration and aqueous extract by infusion. The chemical compositions of the extracts were determined using HPLC-MS/MS technology. The antioxidant activities were examined using various assays including free radical scavenging (ABTS and DPPH), reducing ability (CUPRAC and FRAP), metal chelation, and phosphomolybdenum. The enzyme inhibitory effects were investigated against cholinesterase, tyrosinase, amylase and glucosidase. The highest total phenolics and flavonoids contents were recorded in the methanol extracts of the seed (45.42 mg GAE/g) and aerial parts (40.33 mg RE/g) respectively. The aerial parts were characterized by higher accumulation of chlorogenic acid (9893.86 μg g-1 ), isoquercitrin (9400.33 μg g-1 ), delphindin 3,5 diglucoside (9113.28 μg g-1 ), hyperoside (6337.09 μg g-1 ), rutin (3489.83 μg g-1 ) and kaempferol-3-glucoside (2872.84 μg g-1 ). Generally, the methanol and aqueous extracts of the two studied parts exerted the best antioxidant activity with highest anti-DPPH (61.99 mg TE/g), anti-ABTS (101.80 mg TE/g) and Cu++ (16169 mg TE/g) and Fe+++ (172,36 mg TE/g) reducing capacity were recorded from the seed methanol extract. Methanol extract of the seed showed the best anti-tyrosinase activity (75.86 mg KAE/g). These results indicated that V. peregrina is rich with bioactive phenolics suggesting their use in different health promoting applications.

NtERF4 promotes the biosynthesis of chlorogenic acid and flavonoids by targeting PAL genes in Nicotiana tabacum.

Chlorogenic acid (CGA) and flavonoids are important secondary metabolites, which modulate plant growth and development, and contribute to plant resistance to various environmental stresses. ERF4 has been shown to be a repressor of anthocyanin accumulation in grape, but its full roles in regulating the biosynthesis of other phenylpropanoid compounds still needs to be further studied. In the present study, two NtERF4 genes were identified from N. tabacum genome. The expression level of NtERF4a was higher than that of NtERF4b in all the tobacco tissues examined. Over-expression of NtERF4a significantly promoted the accumulation of CGA and flavonoids in tobacco leaves, while silencing of NtERF4a significantly repressed the biosynthesis of CGA and flavonoids. RNA-seq analysis of NtERF4a-OE and WT plants revealed 8 phenylpropanoids-related differentially expressed genes (DEGs), including 4 NtPAL genes that encode key enzymes in the phenylpropanoid pathway. Activation of NtERF4a-GR fusion protein in tobacco significantly induced the transcription of NtPAL1 and NtPAL2 in the presence of protein synthesis inhibitor. Chromatin immunoprecipitation and Dual-Luc assays further indicated that NtERF4a could bind to the GCC box presented in the promoters of NtPAL1 and NtPAL2, thereby activating their transcription. Moreover, ectopic expression of NtERF4a induced the transcription of NtGSK1, NtMYC2, and NtJAZ3 genes, and enhanced the resistance of tobacco seedlings to salt and drought stresses, indicating multiple roles of NtERF4a in plants. Our findings revealed new roles of NtERF4a in modulating the accumulation of phenylpropanoid compounds in tobacco, and provided a putative target for improving phenylpropanoids synthesis and stress resistance in plants.

Comparative Study on the Chemical Profile, Antioxidant Activity, and Enzyme Inhibition Capacity of Red and White Hibiscus sabdariffa Variety Calyces.

Hibiscus sabdariffa L. (Family: Malvaceae) is believed to be domesticated by the people of western Sudan sometime before 4000 BC for their nutritional and medicinal properties. This study aimed to investigate the chemical profile, antioxidant activity, and enzyme inhibition property of extracts from red roselle (RR) and white roselle (WR) varieties grown in Sudan. Three aqueous extracts obtained by maceration, infusion, and decoction, in addition to the methanolic one, were prepared from the two roselle varieties. Results showed that the highest total phenolic and flavonoid contents of RR were obtained from the extracts prepared by infusion (28.40 mg GAE/g) and decoction (7.94 mg RE/g) respectively, while those from the WR were recorded from the methanolic extract (49.59 mg GAE/g and 5.81 mg RE/g respectively). Extracts of RR were mainly characterized by high accumulation of chlorogenic acid (6502.34-9634.96 mg kg-1), neochlorogenic acid (937.57-8949.61 mg kg-1), and gallic acid (190-4573.55 mg kg-1). On the other hand, neochlorogenic acid (1777.05-6946.39 mg kg-1) and rutin (439.29-2806.01 mg kg-1) were the dominant compounds in WR. All extracts from RR had significant (p < 0.05) higher antioxidant activity than their respective WR except in their metal chelating power, where the methanolic extract of the latter showed the highest activity (3.87 mg EDTAE/g). RR extracts prepared by infusion recorded the highest antioxidant values (35.09, 52.17, 65.62, and 44.92 mg TE/g) in the DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), CUPRAC (cupric ion reducing antioxidant capacity), and FRAP (ferric reducing antioxidant power) assays, respectively. All aqueous extracts from the WR exerted significant (p < 0.05) acetylcholinesterase (AChE) inhibitory activity (3.42-4.77 mg GALAE/g; GALAE = galantamine equivalents), while only one extract, obtained by maceration, from RR exerted AChE inhibitory activity (4.79 mg GALAE/g). All extracts of the RR showed relatively higher BChE (butyrylcholinesterase) inhibitory activity (3.71-4.23 mg GALAE/g) than the WR ones. Methanolic extracts of the two roselle varieties displayed the highest Tyr (tyrosinase) inhibitory activity (RR = 48.25 mg KAE/g; WR = 42.71 mg KAE/g). The methanolic extract of RR exhibited the highest amylase (0.59 mmol ACAE/g) and glucosidase (1.46 mmol ACAE/g) inhibitory activity. Molecular docking analysis showed that delphinidin 3,5-diglucoside, rutin, isoquercitrin, hyperoside, and chlorogenic acid exerted the most promising enzyme inhibitory effect. In conclusion, these findings indicated that the chemical profiles and biological activity of roselle varied according to the variety, extraction solvent, and technique used. These two roselle varieties can serve as a valuable source for the development of multiple formulations in food, pharmaceutical, and cosmetic industries.

Effect of mixed light emitting diode spectrum on antioxidants content and antioxidant activity of red lettuce grown in a closed soilless system

BackgroundLight spectra have been demonstrated to result in different levels of comfort or stress, which affect plant growth and the availability of health-promoting compounds in ways that sometimes contradict one another. To determine the optimal light conditions, it is necessary to weigh the vegetable’s mass against the amount of nutrients it contains, as vegetables tend to grow poorly in environments where nutrient synthesis is optimal. This study investigates the effects of varying light conditions on the growth of red lettuce and its occurring nutrients in terms of productivities, which were determined by multiplying the total weight of the harvested vegetables by their nutrient content, particularly phenolics. Three different light-emitting diode (LED) spectral mixes, including blue, green, and red, which were all supplemented by white, denoted as BW, GW, and RW, respectively, as well as the standard white as the control, were equipped in grow tents with soilless cultivation systems for such purposes.ResultsResults demonstrated that the biomass and fiber content did not differ substantially across treatments. This could be due to the use of a modest amount of broad-spectrum white LEDs, which could help retain the lettuce’s core qualities. However, the concentrations of total phenolics and antioxidant capacity in lettuce grown with the BW treatment were the highest (1.3 and 1.4-fold higher than those obtained from the control, respectively), with chlorogenic acid accumulation (8.4 ± 1.5 mg g− 1 DW) being particularly notable. Meanwhile, the study observed a high glutathione reductase (GR) activity in the plant achieved from the RW treatment, which in this study was deemed the poorest treatment in terms of phenolics accumulation.ConclusionIn this study, the BW treatment provided the most efficient mixed light spectrum to stimulate phenolics productivity in red lettuce without a significant detrimental effect on other key properties.

High-resolution genome mapping and functional dissection of chlorogenic acid production in Lonicera maackii.

Amur honeysuckle (Lonicera maackii) is a widely used medicinal plant of the Caprifoliaceae family that produces chlorogenic acid. Research on this plant mainly focuses on its ornamental value and medicinal compounds, but a reference genome sequence and molecular resources for accelerated breeding are currently lacking. Herein, Nanopore sequencing and high-throughput chromosome conformation capture (Hi-C) allowed a chromosome-level genome assembly of Lonicera maackii (2n = 18). A global view of the gene regulatory network involved in the biosynthesis of chlorogenic acid and the dynamics of fruit coloration in L. maackii was established through metabolite profiling and transcriptome analyses. Moreover, we identified the genes encoding hydroxycinnamoyl-CoA quinate transferase (LmHQT) and hydroxycinnamoyl-CoA shikimic/quinate transferase (LmHCT), which localized to the cytosol and nucleus. Heterologous overexpression of these genes in Nicotiana benthamiana leaves resulted in elevated chlorogenic acid contents. Importantly, HPLC analyses revealed that LmHCT and LmHQTs recombinant proteins modulate the accumulation of chlorogenic acid (CGA) using quinic acid and caffeoyl CoA as substrates, highlighting the importance of LmHQT and LmHCT in chlorogenic acid biosynthesis. These results confirmed that LmHQTs and LmHCT catalyze the biosynthesis of CGA in vitro. The genomic data presented in this study will offer a valuable resource for the elucidation of CGA biosynthesis and facilitating selective molecular breeding.

Full-length transcriptome sequencing and transgenic tobacco revealed the key genes in the chlorogenic acid synthesis pathway of Sambucus chinensis L.

Chlorogenic acid is a key chemical in antioxidation and antisepsis. Sambucus chinensis L. is a herbaceous plant rich in chlorogenic acid and a potential genetic resource for breeding high-chlorogenic acid plants. However, there are few studies on the synthesis pathway of chlorogenic acid in S. chinensis. Our study found chlorogenic acid accumulation in S. chinensis to be organ-specific, higher in leaves and buds but lower in roots, stems and fruits. A total number of 546,844 CCS (Circular Consensus Sequence), including 402,767 full-length non-chimeric (FLNC) and 39 annotated sequences related to the synthesis of chlorogenic acid, was obtained by single-molecule real-time sequencing technology (SMRT). qRT-PCR showed that a number of key genes involved in chlorogenic acid synthesis were differentially expressed in various tissues of S. chinensis. Transgenic tobacco revealed that ectopic expression of the HCT homologous gene HCT-45178 increased the content of chlorogenic acid. Our results should be the first report of full-length transcriptome data of S. chinensis, which help to understand the basis of chlorogenic acid synthesis and provide a novel strategy for breeding tobacco cultivars with higher levels of chlorogenic acid. This article is protected by copyright. All rights reserved.

Light plays a critical role in the accumulation of chlorogenic acid in Lonicera macranthoides Hand.-Mazz

Light has important effects on plant metabolism. However, the relationship between the chlorogenic acid (CGA) content and light in plants remains unclear. Here, we investigated the effects of shading treatment on gene expression and CGA content in Lonicera macranthoides Hand.-Mazz. (LM), a widely used medicinal plant. A total of 1891 differentially expressed genes (DEGs) were obtained in flower buds and 819 in leaves in response to light in shading treatment compared to the control sample by RNA-Seq. After shading treatment, the content of CGA in LM leaves decreased significantly by 1.78-fold, the carotenoid content increased, and the soluble sugar and starch contents significantly decreased. WGCNA and the expression of related genes verified by qRT‒PCR revealed that CGA synthesis pathway enzyme genes form a co-expression network with genes for carbohydrate synthesis, photosynthesis, light signalling elements, and transcription factor genes (TFs) that affect the accumulation of CGA. Through a virus-induced gene silencing (VIGS) system and CGA assay in Nicotiana benthamiana (NB), we determined that downregulation of NbHY5 expression decreased the CGA content in NB leaves. In this study, we found that light provides energy and material for the accumulation of CGA in LM, and light affects the expression of CGA accumulation-related genes. Our results show that different light intensities have multiple effects on leaves and flower buds in LM and are able to coregulate LmHY5 expression and CGA synthesis.

Differential metabolites and their transcriptional regulation in seven major tea cultivars (Camellia sinensis) in China

Various genetic and biochemical characteristics exist in tea plant cultivars, and they largely determine production suitability and tea quality. Here, we performed transcriptomic and metabolomic analyses of young shoots of seven tea cultivars and identified major regulatory transcription factors (TFs) for the characteristic metabolites in different cultivars based on weighted gene co-expression network analysis (WGCNA). Phenotypically, we found that ‘Tieguanyin’ (TGY) and ‘Fujian Shuixian’ (FJSX), which are suitable for oolong tea, had higher catechin contents. The metabolites of ‘Jinxuan’ (JX) were more prominent, especially the contents of phenolic acids, flavonoids, terpenes, and tannins, which were higher than those of the other six cultivars. Moreover, ‘Fudingdabai’ (FDDB), which is suitable for white tea, was rich in amino acids, linolenic acid, and saccharides. At the molecular level, hydroxycinnamoyl CoA quinate hydroxycinnamoyl transferase (HCT) (CsTGY12G0001876, and CsTGY06G0003042) led to the accumulation of chlorogenic acid in TGY. The main reason for the higher l-ascorbic acid content in FJSX was the high expression levels of L-galactono-1,4-lactone hydrogenase (GalLDH) (CsTGY13G0000389) and Myo-inositol oxygenase (MIOX) (CsTGY14G0001769, and CsTGY14G0001770), which were regulated by WRKY (CsTGY11G0001197). Furthermore, FDDB, ‘Longjing 43’ (LJ43), ‘Shuchazao’ (SCZ) and ‘Baihaozao’ (BHZ) had higher free fatty acid contents, among which MYB (CsTGY14G0002344) may be a hub gene for the regulation of palmitoleic acid accumulation. More importantly, we found that the shoots of TGY were green with purple, mainly due to the accumulation of anthocyanins and the downregulation of the Mg-protoporphyrin IX nonomethyl ester cyclase (MPEC) (CsTGY10G0001989) gene that affects chlorophyll synthesis. These results will provide a theoretical reference for tea cultivar breeding and suitability.

Transcriptome Analysis Identifies Genes Associated with Chlorogenic Acid Biosynthesis during Apple Fruit Development

As a predominant phenolic compound in apple fruits, chlorogenic acid (CGA) benefits human health due to its various antioxidant properties. However, little has been known regarding the molecular mechanism underlying the CGA accumulation in apple fruits. In this study, we measured the CGA content and relative enzymes’ activities during fruit development in two different flesh-colored cultivars ‘Huashuo’ and ‘Red Love’. The CGA content in both cultivars decreased sharply from 30 days after full bloom (DAFB) to 60 DAFB. Notably, the CGA content in fruit flesh was relatively higher than that in the peel. Further, the activities of C3H and HCT enzymes downstream of the CGA biosynthesis showed the similar changing trend as CGA content. Based on the transcriptome data of ‘Huashuo’ fruit at 30 DAFB and 60 DAFB, 23 differentially expressed CGA synthesis-related genes were screened. Gene expression analyses further showed that MdHCT1/2/4/5/6 and MdC3H1/2/3 were positively correlated to the variation of CGA content in two cultivars. These findings establish a theoretical foundation for further mechanism study on CGA biosynthesis and provide guidance for nutrient improvement in apple breeding programs.

Effect of Wide-Spectrum Monochromatic Lights on Growth, Phytochemistry, Nutraceuticals, and Antioxidant Potential of In Vitro Callus Cultures of Moringa oleifera.

Moringa oleifera, also called miracle tree, is a pharmaceutically important plant with a multitude of nutritional, medicinal, and therapeutic attributes. In the current study, an in-vitro-based elicitation approach was used to enhance the commercially viable bioactive compounds in an in vitro callus culture of M. oleifera. The callus culture was established and exposed to different monochromatic lights to assess the potentially interactive effects on biomass productions, biosynthesis of pharmaceutically valuable secondary metabolites, and antioxidant activity. Optimum biomass production (16.7 g/L dry weight), total phenolic contents (TPC: 18.03 mg/g), and flavonoid contents (TFC: 15.02 mg/g) were recorded in callus cultures placed under continuous white light (24 h), and of other light treatments. The highest antioxidant activity, i.e., ABTS (550.69 TEAC µM) and FRAP (365.37 TEAC µM), were also noted under white light (24 h). The analysis of phytochemicals confirmed the significant impact of white light exposures on the enhanced biosynthesis of plant secondary metabolites. The enhanced levels of secondary metabolites, i.e., kaempferol (1016.04 µg/g DW), neochlorogenic acid (998.38 µg/g DW), quercetin (959.92 µg/g DW), and minor compounds including luteolin, apigenin, and p-coumaric acid were observed as being highest in continuous white light (24 h with respect to the control (photoperiod). Similarly, blue light enhanced the chlorogenic acid accumulation. This study shows that differential spectral lights demonstrate a good approach for the enhancement of nutraceuticals along with novel pharmacologically important metabolites and antioxidants in the in vitro callus culture of M. oleifera.

Identification and expression analysis of chlorogenic acid biosynthesis key gene PpHCT in peach

Shikimic acid/quinic acid hydroxy cinnamyl transferase (HCT) is one of the key enzymes in the phenylpropanoid pathway. However, the role of the HCT gene in chlorogenic acid (CGA) biosynthesis in peach fruit remains unclear. For this, we identified the accumulation pattern of CGA in four peach cultivars, cloned and characterized 11 PpHCT gene members, and further analyzed the expression patterns of these PpHCT genes during fruit development. The contents of CGAs in the four peach cultivars all exhibited a trend of increasing and then decreasing during the fruit growth and development. Moreover, the contents of CGAs in the peel and flesh were tissue-specific. Gene structure analysis indicated that the PpHCT genes were highly conserved, containing two exons and one intron. The protein structure analysis demonstrated that the PpHCT proteins contained two conserved motifs (HXXXD, DFGWG) and a transferase domain (PF02458), which belonged to the BAHD acyltransferase family. The cis-acting element analysis suggested that the promoters of PpHCT genes contained many light-related, hormone-related, stress-related, tissue-specific, and circadian-related elements, and they could participate in a variety of biological processes. Phylogenetic analysis showed that the HCT proteins of peach were closely related to the HCT proteins of plum and had a close evolutionary relationship. The qRT-PCR analysis indicated that the expression levels of PpHCT1 and PpHCT2 showed an opposite trend to the accumulation of CGA, whereas the expression levels of PpHCT4, PpHCT5, PpHCT7, PpHCT8, and PpHCT11 demonstrated the same trend as CGA accumulation. It was worth noting that only PpHCT4 and PpHCT5 were highly expressed in the two high-CGA cultivars but showed low levels of expression in the two low-CGA cultivars. Therefore, it was hypothesized that these two genes might be key genes to the synthesis of CGA in peach fruit. Those findings provide a theoretical basis for further study on the biological functions of the HCT gene and help to reveal the molecular mechanism of CGA.

Explore the interaction between root metabolism and rhizosphere microbiota during the growth of Angelica sinensis.

Angelica sinensis is a medicinal plant widely used to treat multiple diseases in Asia and Europe, which contains numerous active components with therapeutic value. The interaction between root and rhizosphere microorganisms is crucial for the growth and quality formation of medicinal plants. But the micro-plant-metabolite regulation patterns for A. sinensis remain largely undetermined. Here, we collected roots and rhizosphere soils fromA. sinensisin seedling stage (M) and picking stage (G), respectively cultivated for one year and two years, generated metabolite for roots, microbiota data for rhizospheres, and conducted a comprehensive analysis. Changes in metabolic and microbial communities ofA.sinensisover growth were distinct. The composition of rhizosphere microbes in G was dominated by proteobacteria, which had a strong correlation with the synthesis of organic acids, while in M was dominated by Actinobacteria, which had a strong correlation with the synthesis of phthalide and other organoheterocyclic compounds, flavonoids, amines, and fatty acid. Additionally, co-occurrence network analysis identified thatArthrobacterwas found to be strongly correlated with the accumulation of senkyunolide A and n-butylidenephthalide.JGI 0001001.H03was found to be strongly correlated with the accumulation of chlorogenic acid. Based on rhizosphere microorganisms, this study investigated the correlation between root metabolism and rhizosphere microbiota of A. sinensis at different growth stages in traditional geoherb region, which could provide references for exploring the quality formation mechanism of A. sinensis in the future.

Changes in Phenolic Compounds and Antioxidant Activity during Development of ‘Qiangcuili’ and ‘Cuihongli’ Fruit

Plums are widely consumed, contain high levels of phenolic compounds, and have strong antioxidant activity. In this study, the main Sichuan cultivars ‘Qiangcuili’ and ‘Cuihongli’ were used to study the changes in the appearance, internal quality, phenolic compounds, and antioxidant activities during fruit development and the expression of phenolic-compound-related structural genes. The results showed that, during development of the two plums, the total soluble solid and soluble sugar contents were highest at the mature stage. The phenolic contents (total phenol content (TPC), total flavonoid content (TFC), and total flavanol content (TFAC)) trended gradually downward as the fruits of the two cultivars matured, while the total anthocyanin content gradually increased in ‘Cuihongli’. The main phenolic components were neochlorogenic acid, chlorogenic acid, ferulic acid, benzoic acid, rutin, and proanthocyanidin B1. The changes in the DPPH and FRAP scavenging activities decreased with fruit ripening. The antioxidant capacity was positively correlated with the TPC, TFC, and TFAC. In the two cultivars, the total phenols, phenolic components, and antioxidant capacity were higher in the peel than in the pulp. CHS, PAL3, and HCT1 may be the regulatory genes related to the accumulation of phenolic substances in the pericarp and pulp of ‘Qiangcuili’ and ‘Cuihongli’. HCT1 may be an important regulator involved in the accumulation of chlorogenic acid in plums. The changes in the quality of the phenols, phenolic components, and antioxidant activity were elucidated during the development of the main plum cultivars in Sichuan, particularly the changes that provided a theoretical basis for the development of bioactive substances in local plum cultivars.

Comparative Transcriptome Analysis to Identify Candidate Genes Related to Chlorogenic Acid and Flavonoids Biosynthesis in Iridaceae

Iris (Iridaceae) is one of the most widely admired ornamental plants. It has been used mainly in medicine due to the high concentration of chlorogenic acid (CGA), flavonoids, isoflavones, lignans, and other compounds in its rhizomes. In iris, the gene functions related to CGA and flavonoids biosynthesis are still unclear. In this study, we compared the I. germanica rhizome with a high accumulation level of CGA but a low accumulation level of flavonoids, and the I. pallida rhizome with a low accumulation level of CGA but a high accumulation level of flavonoids at the transcriptome and metabolome levels. A total of 761 metabolites were detected, including 202 flavonoids and 106 phenolic acids based on metabolome profiling. In total, 135 flavonoids were highly accumulated in I. pallida, including three flavanols, 51 flavonoids, 12 flavonoid carbonosides, 31 flavonols, and 21 isoflavones. Based on single-molecule long-read sequencing technology, 94,461 transcripts were identified in iris. Expression analysis indicated that the high accumulation level of C4H and 4CL in I. germanica were essential for CGA accumulation, while CHS, DFR, ANS, ANR, LAR, and 3GT were essential for flavonoids biosynthesis in I. pallida. Many transcription factors such as transcript_83288 (MYB), transcript_57970 (WRKY), and transcript_77465 (WRKY) act as regulators, playing important roles in these biological processes. Our findings provide new insights into the molecular mechanisms associated with the biosynthesis and regulation of flavonoids and CGA in the iris rhizome, and highlight the usefulness of an integrated approach for understanding this process.

Effects of light quality, photoperiod, CO2 concentration, and air temperature on chlorogenic acid and rutin accumulation in young lettuce plants

Environmental stimuli modulate plant metabolite accumulation, facilitating adaptation to stressful conditions. In this study, the effects of blue and red light, photoperiod, CO2 concentration, and air temperature on the chlorogenic acid (CGA) and rutin contents of lettuce (Lactuca sativa L.) were evaluated. Under continuous blue light and a high CO2 concentration (1000 ppm), the CGA level increased. The increased expression of phenylalanine ammonia-lyase (PAL) and activity of its product were correlated with high expression of cinnamate 4-hydroxylase (C4H) and coumarate 3-hydroxylase (C3H). Furthermore, changes in PAL activity altered the CGA content in lettuce exposed to the three environmental factors, blue light, continuous lighting and high CO2 concentration. In addition, the expression levels of genes related to flavonoid biosynthesis increased in accordance with the promotion of CGA accumulation by the environmental factors. Under continuous blue light, 400 ppm CO2 promoted rutin accumulation to a greater degree compared to 1000 ppm CO2, by downregulating DFR expression. Low air temperature induced CGA accumulation in lettuce grown under continuous blue light and 1000 ppm CO2. Therefore, light quality, photoperiod, CO2 concentration, and air temperature exert synergistic effects on the CGA and rutin contents of lettuce by modulating activity in the corresponding biosynthesis pathways.