Functional characterization of sesquiterpene synthase in Mongolian medicine Syringa oblata in heartwood formation.

Lilac (Syringa oblata) is a well-known horticultural plant, and its aromatic heartwood is widely utilized in Traditional Mongolian Medicine for treating angina. However, limited research on the dynamic changes and mechanisms of aromatic substance formation during heartwood development hinders the analysis and utilization of its medicinal components. In this study, volatile metabolome analysis revealed that sesquiterpenes are the primary metabolites responsible for the aroma in heartwood, with cadinane and eremophilane types being the most prevalent. Among the identified sesquiterpene synthases, SoSTPS1-5 exhibited significantly increased expression in heartwood formation and was selected for further investigation. Molecular docking simulations predicted multiple amino acid binding sites and confirmed its ability to catalyze the formation of eremophilane, copaene, cadinane, germacrane, and elemane-type sesquiterpenes from FPP (farnesyl pyrophosphate). Co-expression and promoter analysis suggested a transcriptional regulatory network primarily involving WRKY transcription factors. Additionally, aiotic and biotic stress inducers, such as Ag+, Fusarium oxysporum, and especially MeJA, were found to activate the expression of SoSTPS1-5 and promote sesquiterpene accumulation. This study provides insights into the basis of medicinal substance formation and the potential mechanisms of sesquiterpene accumulation in lilac heartwood, laying a foundation for future research on the biosynthesis and utilization of its medicinal components.

[A new sesquiterpene from Syringa oblata].

In this study, the chemical components of ethanol extract from the aromatic parts of Syringa oblata were systematically separated and purified by silica gel column chromatography, thin layer plate preparation and liquid phase preparation. Combined with ultraviolet analyzer(UV), infrared analyzer(IR), nuclear magnetic resonance analyzer(NMR), high resolution mass spectrometer(HR-ESI-MS), X-ray diffraction and other spectrum technology as well as literature physicochemical data comparison methods for structural identification, a total of 10 compounds were identified. They were identified as oblatanoid D(1),(-)-T-muurolol(2), oblatanoid E-G(3-5), 14-noreudesma-3-hydroxy-3-en-2,9-dione(6), 1-isopropyl-2,7-dimethylnaphthalene(7), isocoradiol(8), α-calacorene(9), cadin-4-en-1-ß-ol(10). Compound 1 is a new sesquiterpene compound that has not been reported, and the other 9 compounds are isolated from S. oblata for the first time. The compound 1 has a significant protective effect on the LPS-induced inflammatory injury model of RAW264.7 cells.

The complete chloroplast genome sequence of Syringa oblata Lindl. var. alba Hort. ex Rehd. 1763 (Oleaceae).

Syringa oblata var. alba is a shrub or a small tree from China with high ornamental, medicinal, and edible value. Here, we present its first complete chloroplast genome. The entire circular genome is 155,648 bp in length, with large single-copy (LSC) length of 86,247, small single-copy (SSC) length of 17,937, inverted repeat (IR) length of 25,732, and GC content of 37.9%. One hundred and thirty-two genes, including 88 protein-coding, 36 tRNA, and eight rRNA genes were predicted. A phylogenetic tree of 25 plant species was constructed based on the maximum-likelihood method, indicating that S. oblata var. alba, S. vulgaris, and S. oblata form a sister group. This study will provide valuable basic information for phylogeny, species identification, and varieties breeding of this species.

Potential antioxidative components from Syringa oblata Lindl stems revealed by affinity ultrafiltration with multiple drug targets.

Traditional Chinese medicine is the main source of natural products due to its remarkable clinical efficacy. Syringa oblata Lindl (S. oblata) was widely used because of its extensive biological activities. However, to explore the antioxidant components of S. oblata against tyrosinase, the experiments of antioxidation in vitro were employed. At the same time, the determination of TPC was also use to assess the antioxidant ability of CE, MC, EA and WA fractions and the liver protective activity of the EA fraction was evaluated by mice in vivo. Next, UF-LC-MS technology was performed to screen and identify the efficient tyrosinase inhibitors in S. oblata. The results showed that alashinol (G), dihydrocubebin, syripinin E and secoisolariciresinol were characterized as potential tyrosinase ligands and their RBA values were 2.35, 1.97, 1.91 and 1.61, respectively. Moreover, these four ligands can effectively dock with tyrosinase molecules, with binding energies (BEs) ranging from 0.74 to -0.73 kcal/mol. In addition, tyrosinase inhibition experiment was employed to evaluate the tyrosinase inhibition activities of four potential ligands, the result showed that compound 12 (alashinol G, IC50 = 0.91 ± 0.20 mM) showed the strongest activity to tyrosinase, followed by secoisolariciresinol (IC50 = 0.99 ± 0.07 mM), dihydrocubebin (IC50 = 1.04 ± 0.30 mM) and syripinin E (IC50 = 1.28 ± 0.23 mM), respectively. The results demonstrate that S. oblata might have excellent antioxidant activity, and UF-LC-MS technique is a effective means to filter out tyrosinase inhibitors from natural products.

The Ethanol Extract of Syringa oblata Heartwood, a Mongolian Folk Medicine Containing Major Lignans, Exerts Analgesic and Sedative Effects on Mice.

The heartwood of Syringa oblata Lindl. (SO) is one of Mongolian folk medicines to treat insomnia and pain, while its pharmacological evaluation and underlying mechanism remain unclear. In this study, the sedative effect of ethanol extract of SO (ESO) was evaluated with the locomotor activity test and the threshold dose of pentobarbital sodium-induced sleep test in mice, and the hot plate test, acetic acid-induced writhing test, and formalin test in mice were used to evaluate its analgesic effect. The underlying mechanism of ESO analgesia was explored by RT-PCR and western blot analysis, which is associated with the regulation of the NF-κB signaling pathway. Besides, the main constituents of ESO were characterized by LC/MS data analysis and comparison with isolated pure compounds. The current findings brought evidence for clinical application and further pharmacological and phytochemical studies on SO.

Phytochemical and pharmacological progress on Syringa oblata, a traditional Mongolian medicine.

Syringa oblata is a traditional Mongolian medicine mainly distributed in the Helan Mountains (the boundaries of Inner Mongolia and Ningxia, China) and the north of Yan Mountains (Aohan Qi, Inner Mongolia, China). It is clinically used to treat diseases caused by Heyi, such as heartache and heat pathogen in the heart. Phytochemical studies on S. oblata revealed the presence of iridoids, lignans, triterpenes, phenylpropanoids, phenylethanoids, and volatile components. Pharmacological investigations revealed a broad spectrum of bioactivities, such as antimicrobial, antioxidant, antiproliferative, and hepatoprotective effects. This article summarized the chemical components and pharmacological activities of S. oblata, providing a scientific rationale for its bioactive constituents, quality control, and utilization as an important medicine.

Active components and molecular mechanism of Syringa oblata Lindl. in the treatment of endometritis based on pharmacology network prediction.

Antibiotic treatment of endometritis was limited by the inevitable antibiotic residues and risk of bacterial resistance. Therefore, the development of safe and effective strategies for endometritis treatment is urgently needed. Syringa oblata Lindl. (SOL) showed great pharmacological potential against endometritis. However, the active components and underlying mechanism of SOL for endometritis treatment remain indeterminate. In our study, the active components and possible molecular mechanism of SOL against endometritis were predicted through computer data mining and biological networks construction. It was predicted that the main active components of SOL were luteolin, kaempferol, oleanolic acid, and rutin, and their anti-endometritis effect was mainly attributed to the TLRs/NF-κB signaling pathway. Furthermore, a green and efficient deep eutectic solvent combined with ultrasound-assisted extraction (DES-UAE) was performed and optimized to obtain high contents of total flavonoid, rutin, and luteolin. The four predicted active components in the SOL extracts were qualitatively and quantitatively analyzed by LC/MS and HPLC. Finally, the pharmacological effects of SOL and active components have been verified by Staphylococcus aureus-endometritis models in mice. H&E staining and bacterial load in uterus tissues assays initially validated the pharmacodynamic effects of SOL, and quantitative real-time PCR (RT-qPCR) and ELISA results confirmed that SOL and four active components could ameliorate the uterus injury caused by Staphylococcus aureus, the mechanism of action is related to the TLRs/NF-κB signaling pathway.

Effect of clove on improving running ability in aging mice.

In this study, a D-galactose-induced aging mouse model was established, and Syringa oblata Lindl. extract (SOLE) was administered orally to observe the effect and mechanism of SOLE on the running ability of aging mice. The role of SOLE was evaluated by H&E histopathological observation, detection of serum biochemical indices, and detection of mRNA expression levels by qPCR experiments. The experimental results showed that SOLE could increase the exhaustive running time of aging mice and reduce the oxidative aging of the liver and kidney. At the same time, the levels of BUN, lactic acid, GOT, GPT, MDA, iNOS, and TNF-α in the serum of the mice were decreased, and the relative mRNA expression levels of nNOS, iNOS, TNF-α and syncytin-1 in the liver tissue and skeletal muscle tissue of the mice were downregulated. In addition, it increased the levels of CAT, GSH-Px, and T-SOD in mouse serum and upregulated the relative mRNA expression of Cu/Zn-SOD, Mn-SOD, and CAT in mouse liver tissue and muscle tissue. The analysis results showed that SOLE mainly contained rutin, isoquercitrin, ferulic acid, dihydroquercetin, and quercitrin. In summary, SOLE can enhance the running ability and exercise ability of aging mice and slow down aging. PRACTICAL APPLICATIONS: Clove is used as health tea or traditional Chinese medicine in China, but there is no relevant research and application on the improvement of human exercise ability. This study found this new function of clove, which accumulated a theoretical basis for further popularizing its application.

Eremophilane and Cadinene Sesquiterpenes from Syringa oblata and Their Protective Effects against Hypoxia-Induced Injury on H9c2 Cells.

Seven sesquiterpenes including four eremophilanes (1-4) and three cadinenes (5-7), were isolated from the heartwood of Syringa oblata Lindl. Among them, three new eremophilane-type sesquiterpenes were identified and named oblatanoids A-C (1-3), respectively. Their structures were established by extensive analyses of spectroscopic methods, and their absolute configurations were determined by electronic circular dichroism (ECD) calculations. All these new compounds were evaluated for protective effects against hypoxia-induced injury on H9c2 cells, and 1-3 exhibited significantly protective activities toward H9c2 cells in vitro.

[Mechanism of Syringa oblata in treating angina pectoris based on GC-MS and network pharmacology].

The chemical constituents in the volatile oil of Syringa oblata were identified using GC-MS and NIST database. TCMSP and SwissTargetPrediction were employed to predict the potential targets of the active components in S. oblata. Through Online Mendelian Inheritance in Man(OMIM), GeneCards, and Kyoto Encyclopedia of Genes and Genomes(KEGG), we screened out the targets related to the prevention or treatment of angina pectoris by the volatile oil of S. oblata, and then used DAVID 6.8 to annotate the gene ontology(GO) terms and KEGG pathways. The "active components-targets-pathways" network was constructed in Cytoscape 3.6.0, and the key active components and targets of S. oblata were verified by Discovery Studio 2016. Forty-six chemical constituents were identified from the volatile oil of S. oblata; 198 potential targets of the active components and 1 138 targets associated with angina pectoris were predicted. A total of 71 common targets were shared by the active components and the disease, including cytochrome P450 19 A1(CYP19 A1) and prostaglandin G/H synthase 2(PTGS2). The KEGG pathways involved include PPAR, JAK-STAT, TNF, Toll-like receptor and NOD-like receptor signaling pathways. The active components in the volatile oil of S. oblata may play anti-inflammatory and anti-apoptosis roles. This study provides a reliable clue for further explanation of the effective components and the functioning mechanism of S. oblata in the treatment of angina pectoris.

Syringa oblata genome provides new insights into molecular mechanism of flower color differences among individuals and biosynthesis of its flower volatiles.

Syringa oblata is a high ornamental value tree owing to its elegant colors, unique aromas and wide adaptability, however, studies on the molecular mechanism underlying the formation of its ornamental traits are still lacking. Here, we presented a chromosome-scale genome assembly of S. oblata and the final genome size was 1.11 Gb with a contig N50 of 4.75 Mb, anchored on 23 chromosomes and was a better reference for S. oblata transcriptome assembly. Further by integrating transcriptomic and metabolic data, it was concluded that F3H, F3'H, 4CL and PAL, especially the F3'H, were important candidates involved in the formation of floral color differences among S. oblata individuals. Genome-wide identification and analysis revealed that the TPS-b subfamily was the most abundant subfamily of TPS family in S. oblata, which together with the CYP76 family genes determined the formation of the major floral volatiles of S. oblata. Overall, our results provide an important reference for mechanistic studies on the main ornamental traits and molecular breeding in S. oblata.

Mechanism of Syringa oblata in treating angina pectoris based on GC-MS and network pharmacology / 中国中药杂志

The chemical constituents in the volatile oil of Syringa oblata were identified using GC-MS and NIST database. TCMSP and SwissTargetPrediction were employed to predict the potential targets of the active components in S. oblata. Through Online Mendelian Inheritance in Man(OMIM), GeneCards, and Kyoto Encyclopedia of Genes and Genomes(KEGG), we screened out the targets related to the prevention or treatment of angina pectoris by the volatile oil of S. oblata, and then used DAVID 6.8 to annotate the gene ontology(GO) terms and KEGG pathways. The "active components-targets-pathways" network was constructed in Cytoscape 3.6.0, and the key active components and targets of S. oblata were verified by Discovery Studio 2016. Forty-six chemical constituents were identified from the volatile oil of S. oblata; 198 potential targets of the active components and 1 138 targets associated with angina pectoris were predicted. A total of 71 common targets were shared by the active components and the disease, including cytochrome P450 19 A1(CYP19 A1) and prostaglandin G/H synthase 2(PTGS2). The KEGG pathways involved include PPAR, JAK-STAT, TNF, Toll-like receptor and NOD-like receptor signaling pathways. The active components in the volatile oil of S. oblata may play anti-inflammatory and anti-apoptosis roles. This study provides a reliable clue for further explanation of the effective components and the functioning mechanism of S. oblata in the treatment of angina pectoris.

Phytochemical and pharmacological progress on Syringa oblata, a traditional Mongolian medicine / 中草药·英文版

Syringa oblata is a traditional Mongolian medicine mainly distributed in the Helan Mountains (the boundaries of Inner Mongolia and Ningxia, China) and the north of Yan Mountains (Aohan Qi, Inner Mongolia, China). It is clinically used to treat diseases caused by Heyi, such as heartache and heat pathogen in the heart. Phytochemical studies on S. oblata revealed the presence of iridoids, lignans, triterpenes, phenylpropanoids, phenylethanoids, and volatile components. Pharmacological investigations revealed a broad spectrum of bioactivities, such as antimicrobial, antioxidant, antiproliferative, and hepatoprotective effects. This article summarized the chemical components and pharmacological activities of S. oblata, providing a scientific rationale for its bioactive constituents, quality control, and utilization as an important medicine.

The implication of leaf anatomical structure for the selective breeding of lilacs.

The cultivars of the common lilac (Syringa vulgaris) grown in the south of the Russian Far East are not always winter-hardy and are often damaged by fungal diseases due to a very humid climate. A promising trend in the selective breeding of lilacs in Russia is the creation of new breeding material based on the gene pool of the broadleaf lilac (S. oblata) and its hybrids in order to introduce valuable adaptive traits into cultivars. The present work aimed to identify the traits of leaf anatomy in species and cultivars of Syringa resistant and susceptible to Pseudocercospora lilacis, the causative agent of brown leaf spot disease. The study was carried out on the living collection of the Botanical Garden-Institute, Far Eastern Branch, Russian Academy of Sciences (Vladivostok). The leaf anatomical structure of two Syringa species showing different degrees of resistance to P. lilacis in the monsoon climate of the Far East (resistant S. oblata and weakly resistant S. vulgaris, and also their hybrid cultivars) has been analyzed. The differences between species, subspecies, and cultivars are quantitative: they differ in the number of spongy mesophyll layers, the cell height in the f irst layer of palisade mesophyll, the cell height in the upper and lower epidermises, and the thickness of both mesophylls. The interspecif ic hybrids resistant or weakly resistant to P. lilacis (brown leaf spot disease) mainly retain the leaf anatomy structure of the maternal plant. One of the traits determining the resistance of hybrid lilac cultivars is an increased number of spongy mesophyll layers in the leaf blade. The study of leaf anatomy has shown that the four-layered spongy mesophyll leaf parenchyma correlates with the resistance of lilacs from the subsection Euvulgaris to P. lilacis. In S. oblata, this trait is inherited down the maternal line. To establish lilac cultivars resistant to fungal diseases, it is advisable to cross the two species (S. oblata and S. vulgaris) or their cultivars using one of S. oblata subspecies as a maternal plant.

Inhibitory Effect of LGS and ODE Isolated from the Twigs of Syringa oblata subsp. dilatata on RANKL-Induced Osteoclastogenesis in Macrophage Cells.

Osteoblasts and osteoclasts play a pivotal role in maintaining bone homeostasis, of which excessive bone resorption by osteoclasts can cause osteoporosis and various bone diseases. However, current osteoporosis treatments have many side effects, and research on new treatments that can replace these treatments is ongoing. Therefore, in this study, the roles of ligustroside (LGS) and oleoside dimethylester (ODE), a natural product-derived compound isolated from Syringa oblata subsp. dilatata as a novel, natural product-derived osteoporosis treatments were investigated. In the results of this study, LGS and ODE inhibited the differentiation of receptor activator of nuclear factor kappa-Β ligand (RANKL)-induced RAW264.7 cells into osteoclasts without cytotoxicity, and down-regulated the activity of TRAP, a specific biomarker of osteoclasts. In addition, it inhibited bone resorption and actin ring formation, which are important functions and features of osteoclasts. Also, the effects of LGS and ODE on the mitogen-activated protein kinase (MAPK) and nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) and phosphoinositide 3-kinases (PI3K)/ protein kinase B (Akt)/mechanistic target of rapamycin (mTOR) signaling pathways that play important roles in osteoclast differentiation were evaluated. In the results, LGS and ODE downregulated the phosphorylation of RANKL-induced MAPK and PI3K/Akt/mTOR proteins in a concentration-dependent manner, translocation of NF-κB into the nucleus was inhibited. As a result, the compounds LGS and ODE isolated from S. oblate subsp. dilatata effectively regulated the differentiation of RANKL-induced osteoclasts and inhibited the phosphorylation of signaling pathways that play a pivotal role in osteoclast differentiation. Therefore, these results suggest the possibility of LGS and ODE as new natural product treatments for bone diseases caused by excessive osteoclasts.

Dual Functional Eudragit® S100/L30D-55 and PLGA Colon-Targeted Nanoparticles of Iridoid Glycoside for Improved Treatment of Induced Ulcerative Colitis.

AIM: Iridoid glycosides (IG) as the major active fraction of Syringa oblata Lindl. has a proven anti-inflammatory effect for ulcerative colitis (UC). However, its current commercial formulations are hampered by low bioavailability and unable to reach inflamed colon. To overcome the limitation, dual functional IG-loaded nanoparticles (DFNPs) were prepared to increase the residence time of IG in colon. The protective mechanism of DFNPs on DSS-induced colonic injury was evaluated in rats. MATERIALS AND METHODS: We prepared DFNPs using the oil-in-water emulsion method. PLGA was selected as sustained-release polymer, and ES100 and EL30D-55 as pH-responsive polymers. The morphology and size distribution of NPs were measured by SEM and DLS technique. To evaluate colon targeting of DFNPs, DiR, was encapsulated as a fluorescent probe into NPs. Fluorescent distribution of NPs were investigated. The therapeutic potential and in vivo transportation of NPs in gastrointestinal tract were evaluated in a colitis model. RESULTS: SEM images and zeta data indicated the successful preparation of DFNPs. This formulation exhibited high loading capacity. Drug release results suggested DFNPs released less than 20% at the first 6 h in simulated gastric fluid (pH1.2) and simulated small intestine fluid (pH6.8). A high amount of 84.7% sustained release from NPs in simulated colonic fluid (pH7.4) was beyond 24 h. DiR-loaded NPs demonstrated a much higher colon accumulation, suggesting effective targeting due to functionalization with pH and time-dependent polymers. DFNPs could significantly ameliorate the colonic damage by reducing DAI, macroscopic score, histological damage and cell apoptosis. Our results also proved that the potent anti-inflammatory effect of DFNPs is contributed by decrease of NADPH, gene expression of COX-2 and MMP-9 and the production of TNF-α, IL-17, IL-23 and PGE2. CONCLUSION: We confirm that DFNPs exert protective effects through inhibiting the inflammatory response, which could be developed as a potential colon-targeted system.

Effect of Syringopicroside Extracted from Syringa oblata Lindl on the Biofilm Formation of Streptococcus suis.

Syringopicroside is a natural drug with antibacterial activity, which is the main ingredient of Syringa oblata Lindl (S. oblata). In order to further develop the application of S. oblata and evaluate the ability of syringopicroside against Streptococcus suis (S. suis), this investigation first applied an ultrasonic-assisted method to extract syringopicroside, and then response surface methodology (RSM) was performed to get the optimum condition. Based on RSM analysis, a second-order polynomial equation about the syringopicroside yield and four variables, including ultrasonic power, time, temperature, and liquid-to-solid ratio, was purposed. Through RSM prediction and model verification experiments, the optimum conditions were determined, as follows: ultrasonic time was 63 min, temperature was 60 °C, a liquid-to-solid ratio was set to 63 mL/g, and ultrasonic power was 835 W. Under this condition, a high syringopicroside yield was obtained (3.07 ± 0.13 mg/g), which was not significantly different with a predicated value. After separation and purification by HPD 500 microporous resin, then mass spectrum was applied to identify the main ingredient in aqueous extract. A minimal inhibitory concentration (MIC) assay revealed the value against S. suis of syringopicroside was 2.56 µg/µL and syringopicroside with sub-inhibitory concentrations that could effectively inhibit biofilm formation of S. suis. Besides, scanning electron microscopy analysis indicated syringopicroside could destroy the multi-layered aggregation structure of S. suis. Finally, molecular docking analysis confirmed that syringopicroside was combined with Orfy protein of S. suis through hydrogen bonds, hydrophobic interaction, and π-π stacking.

The complete chloroplast genome of Syringa oblata (Oleaceae).

Syringa oblata Lindl. is a popular ornamental shrub with aroma compounds. Here, we sequenced and assembled the complete chloroplast genome of S. oblata. The complete chloroplast genome of S. oblata is 155,648 bp in length, containing a pair of inverted repeated (IRa and IRb) region of 25,732 bp that are separated by a large single copy (LSC) region of 86,247 bp, and a small single copy (SSC) region of 17,937 bp. A total of 132 functional genes were annotated, including 88 protein-coding genes, 36 tRNA genes, and eight rRNA genes. The Neighbour-joining phylogenetic tree based on complete chloroplast genomes suggested that S. oblata is most closely related to S. vulgaris.

Development of EST-SSR markers and association mapping with floral traits in Syringa oblata.

BACKGROUND: Lilac (Syringa oblata) is an important woody plant with high ornamental value. However, very limited genetic marker resources are currently available, and little is known about the genetic architecture of important ornamental traits for S. oblata, which is hindering its genetic studies. Therefore, it is of great significance to develop effective molecular markers and understand the genetic architecture of complex floral traits for the genetic research of S. oblata. RESULTS: In this study, a total of 10,988 SSRs were obtained from 9864 unigene sequences with an average of one SSR per 8.13 kb, of which di-nucleotide repeats were the dominant type (32.86%, 3611). A set of 2042 primer pairs were validated, out of which 932 (45.7%) exhibited successful amplifications, and 248 (12.1%) were polymorphic in eight S. oblata individuals. In addition, 30 polymorphic EST-SSR markers were further used to assess the genetic diversity and the population structure of 192 cultivated S. oblata individuals. Two hundred thirty-four alleles were detected, and the PIC values ranged from 0.23 to 0.88 with an average of 0.51, indicating a high level of genetic diversity within this cultivated population. The analysis of population structure showed two major subgroups in the association population. Finally, 20 significant associations were identified involving 17 markers with nine floral traits using the mixed linear model. Moreover, marker SO104, SO695 and SO790 had significant relationship with more than one trait. CONCLUSION: The results showed newly developed markers were valuable resource and provided powerful tools for genetic breeding of lilac. Beyond that, our study could serve an efficient foundation for further facilitate genetic improvement of floral traits for lilac.

Transcriptomic analysis reveals flavonoid biosynthesis of Syringa oblata Lindl. in response to different light intensity.

BACKGROUND: Hazy weather significantly increase air pollution and affect light intensity which may also affect medicinal plants growth. Syringa oblata Lindl. (S. oblata), an effective anti-biofilm medicinal plants, is also vulnerable to changes in plant photoperiods and other abiotic stress responses. Rutin, one of the flavonoids, is the main bioactive ingredient in S. oblata that inhibits Streptococcus suis biofilm formation. Thus, the present study aims to explore the biosynthesis and molecular basis of flavonoids in S. oblata in response to different light intensity. RESULTS: In this study, it was shown that compared with natural (Z0) and 25% ~ 35% (Z2) light intensities, the rutin content of S. oblata under 50% ~ 60% (Z1) light intensity increased significantly. In addition, an integrated analysis of metabolome and transcriptome was performed using light intensity stress conditions from two kinds of light intensities which S. oblata was subjected to: Z0 and Z1. The results revealed that differential metabolites and genes were mainly related to the flavonoid biosynthetic pathway. We found out that 13 putative structural genes and a transcription factor bHLH were significantly up-regulated in Z1. Among them, integration analysis showed that 3 putative structural genes including 4CL1, CYP73A and CYP75B1 significantly up-regulated the rutin biosynthesis, suggesting that these putative genes may be involved in regulating the flavonoid biosynthetic pathway, thereby making them key target genes in the whole metabolic process. CONCLUSIONS: The present study provided helpful information to search for the novel putative genes that are potential targets for S. oblata in response to light intensity.