Genome-wide characterization of the bHLH gene family in Gynostemma pentaphyllum reveals its potential role in the regulation of gypenoside biosynthesis.

BACKGROUND: Gynostemma pentaphyllum, an ancient Chinese herbal medicine, serves as a natural source of gypenosides with significant medicinal properties. Basic helix-loop-helix (bHLH) transcription factors play pivotal roles in numerous biological processes, especially in the regulation of secondary metabolism in plants. However, the characteristics and functions of the bHLH genes in G. pentaphyllum remain unexplored, and their regulatory role in gypenoside biosynthesis remains poorly elucidated. RESULTS: This study identified a total of 111 bHLH members in G. pentaphyllum (GpbHLHs), categorizing them into 26 subgroups based on shared conserved motif compositions and gene structures. Collinearity analysis illustrated that segmental duplications predominately lead to the evolution of GpbHLHs, with most duplicated GpbHLH gene pairs undergoing purifying selection. Among the nine gypenoside-related GpbHLH genes, two GpbHLHs (GpbHLH15 and GpbHLH58) were selected for further investigation based on co-expression analysis and functional prediction. The expression of these two selected GpbHLHs was dramatically induced by methyl jasmonate, and their nuclear localization was confirmed. Furthermore, yeast one-hybrid and dual-luciferase assays demonstrated that GpbHLH15 and GpbHLH58 could bind to the promoters of the gypenoside biosynthesis pathway genes, such as GpFPS1, GpSS1, and GpOSC1, and activate their promoter activity to varying degrees. CONCLUSIONS: In conclusion, our findings provide a detailed analysis of the bHLH family and valuable insights into the potential use of GpbHLHs to enhance the accumulation of gypenosides in G. pentaphyllum.

Mesenchymal Stem Cell-Derived Exosomes as Drug Delivery Vehicles in Disease Therapy.

Exosomes are small vesicles containing proteins, nucleic acids, and biological lipids, which are responsible for intercellular communication. Studies have shown that exosomes can be utilized as effective drug delivery vehicles to accurately deliver therapeutic substances to target tissues, enhancing therapeutic effects and reducing side effects. Mesenchymal stem cells (MSCs) are a class of stem cells widely used for tissue engineering, regenerative medicine, and immunotherapy. Exosomes derived from MSCs have special immunomodulatory functions, low immunogenicity, the ability to penetrate tumor tissues, and high yield, which are expected to be engineered into efficient drug delivery systems. Despite the promising promise of MSC-derived exosomes, exploring their optimal preparation methods, drug-loading modalities, and therapeutic potential remains challenging. Therefore, this article reviews the related characteristics, preparation methods, application, and potential risks of MSC-derived exosomes as drug delivery systems in order to find potential therapeutic breakthroughs.

Metabolomics analysis reveals the differences between Abrus cantoniensis Hance and Abrus mollis Hance.

BACKGROUND: Abrus cantoniensis Hance. (Ac) and Abrus mollis (Am), two edible and medicinal plants with economic value in southern China, belong to the Abrus genus. Due to its growth characteristics, Am often replaces Ac in folk medicine. However, the latest National Pharmacopeia of China only recommends Ac. The differences in the metabolite composition of the plants are directly related to the differences in their clinical efficacy. RESULTS: The difference in metabolites were analyzed using an untargeted metabolomic approach based on ultrahigh-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC‒ESI‒MS/MS). The roots (R), stems (S) and leaves (L) of the two varieties were examined, and 635 metabolites belonging to 8 classes were detected. A comparative study revealed clear variations in the metabolic profiles of the two plants, and the AmR group had more active ingredients (flavonoids and terpenoids) than the AcR group. The metabolites classified as flavonoids and triterpene saponins showed considerable variations among the various samples. Both Ac and Am had unique metabolites. Two metabolites (isovitexin-2''-xyloside and soyasaponin V) specifically belong to Ac, and nine metabolites (vitexin-2"-O-galactoside, ethyl salicylate, 6-acetamidohexanoic acid, rhein-8-O-glucoside, hederagenin-3-O-glucuronide-28-O-glucosyl(1,2)-glucoside, methyl dioxindole-3-acetate, veratric acid, isorhamnetin-3-O-sophoroside-7-O-rhamnoside, and isorhamnetin-3-O-sophoroside) specifically belong to Am. CONCLUSIONS: The metabolite differences between Ac and Am cause the differences in their clinical efficacy. Our findings serve as a foundation for further investigation of biosynthesis pathways and associated bioactivities and provide guidance for the clinical application of traditional Chinese medicine.

Matrine-producing endophytic fungus Galactomyces candidum TRP-7: screening, identification, and fermentation conditions optimization for Matrine production.

Matrine (MA) is an alkaloid extracted from the root of genus Sophora with various pharmacological activities. Production of MA by endophytic fungi offers an alternative challenge to reduce the massive consumption to meet the increasing demand of MA. In the current study, the positive strains with MA producing ability were screened from endophytic fungal isolated from the root of Sophora tonkinensis Gagnep. Chromatographic analyses verified the identity of the produced MA. Among these fungi, Galactomyces candidum strain TRP-7 was the most valuable strain for MA production with the initial yield 8.26 mg L-1. The MA production was efficiently maximized up to 17.57 mg L-1 of fermentation broth, after optimization of eight process parameters using Plackett-Burman and Box-Behnken designs. The statistical optimization resulted in a 1.127 times increase in MA production as compared to the initial yield of TRP-7. This is the first report to isolate endophytic fungi with MA-producing activity from S. tonkinensis Gagnep., and to identify an endophytic fungus G. candidum TRP-7 as a new promising start strain for a higher MA yield.

Prediction of 5-year overall survival of tongue cancer based machine learning.

OBJECTIVE: We aimed to develop a 5-year overall survival prediction model for patients with oral tongue squamous cell carcinoma based on machine learning methods. SUBJECTS AND METHODS: The data were obtained from electronic medical records of 224 OTSCC patients at the PLA General Hospital. A five-year overall survival prediction model was constructed using logistic regression, Support Vector Machines, Decision Tree, Random Forest, Extreme Gradient Boosting, and Light Gradient Boosting Machine. Model performance was evaluated according to the area under the curve (AUC) of the receiver operating characteristic curve. The output of the optimal model was explained using the Python package (SHapley Additive exPlanations, SHAP). RESULTS: After passing through the grid search and secondary modeling, the Light Gradient Boosting Machine was the best prediction model (AUC = 0.860). As explained by SHapley Additive exPlanations, N-stage, age, systemic inflammation response index, positive lymph nodes, plasma fibrinogen, lymphocyte-to-monocyte ratio, neutrophil percentage, and T-stage could perform a 5-year overall survival prediction for OTSCC. The 5-year survival rate was 42%. CONCLUSION: The Light Gradient Boosting Machine prediction model predicted 5-year overall survival in OTSCC patients, and this predictive tool has potential prognostic implications for patients with OTSCC.

Hybrid integrated ultralow-linewidth and fast-chirped laser for FMCW LiDAR.

Narrow linewidth and fast-chirped frequency are essential in frequency-modulated continuous-wave lasers. We introduce a laser that meets these requirements by coupling a distributed feedback laser with an external high-Q microring resonator, where a bulky stacked piezoelectric chip is attached to the resonator for fast tuning. The laser demonstrates an ultranarrow intrinsic linewidth of 22 Hz in the self-injection-locked state. Actuated by the bulky piezoelectric chip, the maximum triangular actuation bandwidth can reach 100 kHz. The driving voltage is filtered to avoid a resonant mechanical mode, obtaining the minimum residual linearity error at 10 kHz with a 4.2 GHz tuning range. A light detection and ranging system was set up for a proof-of-concept experiment, demonstrating a high detection precision with standard deviations of 2.7 and 4.0 cm for targets at 15 and 30 m, respectively.

Predictive value of systemic inflammatory response-related indices for survival in tongue cancer.

OBJECTIVES: We assessed the potential prognostic significance of the preoperative systemic inflammation index, platelet-to-lymphocyte ratio, and neutrophil-to-lymphocyte ratio in patients who underwent surgical resection. SUBJECTS AND METHODS: This retrospective study included 224 patients with clinicopathologically confirmed squamous carcinoma of the tongue who underwent surgery between August 2009 and December 2017. The optimal cut-off values for the indices were determined by receiver operating characteristic curves. Correlations between the indices and clinicopathological variables were determined by Pearson chi-square or Fisher exact tests. The Kaplan-Meier test was used to compare overall survival between groups (high and low values); the log-rank or Breslow test was used to assess differences in survival. Univariate and multivariate Cox regression models were used to analyze predictive values of the indices as independent indicators of overall survival. Bilateral p values of <0.05 were considered statistically significant. RESULTS: Significant association was found between the indices and sex, tissue grade, tumor location, and lymph nodes metastases (p < 0.05). On Kaplan-Meier analysis, patients with lower values of the indices had longer overall survival (p < 0.05). Univariate and multivariate Cox regression models identified age, lymph node metastases, and neutrophil-to-lymphocyte ratio as independent predictors of overall survival. CONCLUSION: The studied indices have potential prognostic significance in patients with squamous tongue cancer.

Characterization of Volatile Organic Compounds Emitted from Endophytic Burkholderia cenocepacia ETR-B22 by SPME-GC-MS and Their Inhibitory Activity against Various Plant Fungal Pathogens.

The use of antagonistic microorganisms and their volatile organic compounds (VOCs) to control plant fungal pathogens is an eco-friendly and promising substitute for chemical fungicides. In this work, endophytic bacterium ETR-B22, isolated from the root of Sophora tonkinensis Gagnep., was found to exhibit strong antagonistic activity against 12 fungal pathogens found in agriculture. Strain ETR-B22 was identified as Burkholderia cenocepacia based on 16S rRNA and recA sequences. We evaluated the antifungal activity of VOCs emitted by ETR-B22. The VOCs from strain ETR-B22 also showed broad-spectrum antifungal activity against 12 fungal pathogens. The composition of the volatile profiles was analyzed based on headspace solid phase microextraction (HS-SPME) gas chromatography coupled to mass spectrometry (GC-MS). Different extraction strategies for the SPME process significantly affected the extraction efficiency of the VOCs. Thirty-two different VOCs were identified. Among the VOC of ETR-B22, dimethyl trisulfide, indole, methyl anthranilate, methyl salicylate, methyl benzoate, benzyl propionate, benzyl acetate, 3,5-di-tert-butylphenol, allyl benzyl ether and nonanoic acid showed broad-spectrum antifungal activity, and are key inhibitory compounds produced by strain ETR-B22 against various fungal pathogens. Our results suggest that the endophytic strain ETR-B22 and its VOCs have high potential for use as biological controls of plant fungal pathogens.

Novel Substituted Thiophenes and Sulf-Polyacetylene Ester from Echinops ritro L.

Three new substituted bithiophenes (1⁻3), and one new sulf-polyacetylene ester, ritroyne A (16) were isolated from the whole plant of Echinops ritro together with twelve known substituted thiophenes. The structures were elucidated on the basis of extensive spectroscopic analysis including 1D and 2D NMR as well as MS. Furthermore, the absolute configuration of ritroyne A (16) was established by computational methods. In bioscreening experiments, four compounds (2, 4, 12, 14) showed similar antibacterial activity against Staphylococcus aureus ATCC 2592 with levofloxacin (8 µg/mL). Five compounds (2, 4, 9, 12, 14) exhibited antibacterial activities against Escherichia coli ATCC 25922, with minimum inhibitory concentration (MIC) values of 32⁻64 µg/mL. Three compounds (2, 4, 12) exhibited antifungal activities against Candida albicans ATCC 2002 with MIC values of 32⁻64 µg/mL. However, compound 16 did not exhibit antimicrobial activities against three microorganisms.

[Clinical analysis of using hyperbaric oxygen comprehensive therapy for the treatment of 110 cases noise induced deafness].

OBJECTIVE: To observe the clinical effects of using hyperbaric oxygen comprehensive therapy for the treatment of noise induced deafness. METHODS: From May 2009 to April 2012 in our hospital 220 cases of noise induced deafness patients were chosen and they were all construction workers; According to different treatments all patients were divided into the control group (110 cases) only having hyperbaric oxygen treatment and the treatment group (110 cases) using hyperbaric oxygen comprehensive therapy, including control group simply by. Hearing improvements of the two groups were recorded and compared. RESULTS: The cure rate of the comprehensive therapy group was 53.6%which was higher than that of the control group 38.2% (χ(2) = 5.290, P < 5.290), while the total effective rate of the comprehensive therapy group was 79.1%which was also significantly higher than that of the control group 67.3% (χ(2) = 3.914, P < 0.05). After two courses of comprehensive treatment the cure rate and total effective rate were 47.3%and 73.6%respectively, while after four courses of comprehensive treatment group the cure rate and total effective rate turned to be 60.9% and 84.5% respectively, which had significant difference (χ(2) values were 4.118 and 3.958, P < 0.05). CONCLUSIONS: The cure rate and total effective rate of the comprehensive therapy group are higher than the simple hyperbaric oxygen treatment group, which is worthy of clinical application and promotion in the future.

Bacteria from nodules of Abrus mollis Hance: genetic diversity and screening of highly efficient growth-promoting strains.

Introduction: Abrus mollis Hance. (AM) is an important species used in southern Chinese medicine. It is mainly found in Guangdong and Guangxi provinces in China, and it is effective in the treatment of hepatitis. Endophytic bacteria are known to affect the growth and quality of medicinal plants. However, there are limited reports describing endophytic bacteria related to AM. Methods: In the present study, Illumina-based 16S rRNA gene sequencing was used to investigate the endophytic bacterial communities of root nodules of AM at five sampling sites in Guangxi. In addition, 179 strains of endophytic bacteria were isolated and categorized into 13 haplotypes based on recA sequence analysis. Results: The phylogeny of the 16S rRNA gene sequences revealed a predominance of nonrhizobial endophytes. Microbial diversity analysis showed that Proteobacteria was the dominant phylum in all samples, while Bradyrhizobium was the dominant genus in different samples. An efficient strain, Rhizobium tropici FM-19, was screened and obtained through greenhouse experiments. The AM plants inoculated with this strain showed the best growth performance and high nitrogen fixation and nodulation capacity. Notably, total phenols and total flavonoids, important active components in AM, increased by 30.9 and 42.7%, respectively, after inoculation with Rhizobium tropici FM-19. Discussion: This study provides insights into the complex microbial diversity of AM nodules and provides strain information for the efficient cultivation of AM.

Prognostic prediction of patients having classical papillary thyroid carcinoma with a 4 mRNA-based risk model.

The dysregulation of protein-coding genes involved in various biological functions is closely associated with the progression of thyroid cancer. This study aimed to investigate the effects of dysregulated gene expressions on the prognosis of classical papillary thyroid carcinoma (cPTC). Using expression profiling datasets from the Cancer Genome Atlas (TCGA) database, we performed differential expression analysis to identify differentially expressed genes (DEGs). Cox regression and Kaplan-Meier analysis were used to identify DEGs, which were used to construct a risk model to predict the prognosis of cPTC patients. Functional enrichment analysis unveiled the potential significance of co-expressed protein-encoding genes in tumors. We identified 4 DEGs (SALL3, PPBP, MYH1, and SYNDIG1), which were used to construct a risk model to predict the prognosis of cPTC patients. These 4 genes were independent of clinical parameters and could be functional in cPTC carcinogenesis. Furthermore, PPBP exhibited a strong correlation with poorer overall survival (OS) in the advanced stage of the disease. This study suggests that the 4-gene signature could be an independent prognostic biomarker to improve prognosis prediction in cPTC patients older than 46.

Genome-wide identification and characterization of the JAZ gene family in Gynostemma pentaphyllum reveals the COI1/JAZ/MYC2 complex potential involved in the regulation of the MeJA-induced gypenoside biosynthesis.

The Jasmonate ZIM domain (JAZ) proteins, functioning as critical suppressors for jasmonic acid (JA) signal transduction in plants, occupy crucial roles in multiple biological processes, particularly in the orchestration of secondary metabolic pathways. However, the mechanism underlying the JA-induced gypenosides accumulation in Gynostemma pentaphyllum remains poorly elucidated. Our research led to the identification of 11 distinct JAZ members in G. pentaphyllum (GpJAZs). According to the classification approach of AtJAZ, we allocated these members into five subgroups that shared similar conserved motif compositions. Subsequently, we identified the presence of various cis-acting elements associated with light stimuli, hormone responses, and stress signals within the promoter regions of the GpJAZ gene family. The expression levels of GpJAZ genes in different tissues were quite different, and the majority of GpJAZ genes exhibited varying degrees of response to methyl jasmonate (MeJA) induction. Yeast two-hybrid (Y2H) assays revealed interactions between GpJAZ1/2/4/5/7/9/10 and GpMYC2, whereas GpCOI1 protein was found to interact with GpJAZ1/2/4/5, thereby forming the COI1/JAZ/MYC2 complex. Furthermore, as an activator of gypenoside metabolic pathway, GpMYC2 could activate the promoter activity of the gypenoside metabolism-related genes to varying degrees by binding to their promoters, indicating that the COI1/JAZ/MYC2 module involved in the MeJA-induced regulation of gypenosides. In summary, our findings present an exhaustive examination of the JAZ gene family, furnishing a significant lead for delving deeper into the molecular mechanisms that drive the MeJA-induced enhancement of gypenosides accumulation in G. pentaphyllum.

Alkaloid variations within the genus Stephania (Menispermaceae) in China.

The genus Stephania, which is rich in alkaloids, has been used as a traditional medicine or folklore herb against numerous ailments in China. However, the understanding of the variation within the genus Stephania is obscure, which limits the optimal utilization of the genus. An evaluation of the variation within the genus Stephania would help screen the ideal Stephania genotypes for drug utilization. In the present study, alkaloids in the tubers of four commonly cultivated Stephania species in China, i.e., the genotype Stephania kwangsiensis Lo. (SK-guangxi) from Guangxi Province and three Stephania yunnanensis H.S. Lo. genotypes (SY-xueteng, SY-hongteng, and SY-lvteng) sourced from Yunnan Province, were investigated, and the genus variations were compared. The results revealed significant variations in the abundance of alkaloids in tubers within the genus Stephania. The Stephania genotypes SY-xueteng and SY-hongteng showed a relatively high abundance of total alkaloids compared with the Stephania genotypes SK-guangxi and SY-lvteng. Specifically, the Stephania genotype SY-xueteng had a relatively high abundance of palmatine in tubers, and the Stephania genotype SY-hongteng exhibited a high abundance of stephanine in tubers. Our study provides foundations for further utilization of ideal Stephania genotypes by clarifying the variations in the alkaloid contents within the genus in China.

Predicting cervical lymph node metastasis in OSCC based on computed tomography imaging genomics.

BACKGROUND: To investigate the correlation between computed tomography (CT) radiomic characteristics and key genes for cervical lymph node metastasis (LNM) in oral squamous cell carcinoma (OSCC). METHODS: The region of interest was annotated at the edge of the primary tumor on enhanced CT images from 140 patients with OSCC and obtained radiomic features. Ribonucleic acid (RNA) sequencing was performed on pathological sections from 20 patients. the DESeq software package was used to compare differential gene expression between groups. Weighted gene co-expression network analysis was used to construct co-expressed gene modules, and the KEGG and GO databases were used for pathway enrichment analysis of key gene modules. Finally, Pearson correlation coefficients were calculated between key genes of enriched pathways and radiomic features. RESULTS: Four hundred and eighty radiomic features were extracted from enhanced CT images of 140 patients; seven of these correlated significantly with cervical LNM in OSCC (p < 0.01). A total of 3527 differentially expressed RNAs were screened from RNA sequencing data of 20 cases. original_glrlm_RunVariance showed significant positive correlation with most long noncoding RNAs. CONCLUSIONS: OSCC cervical LNM is related to the salivary hair bump signaling pathway and biological process. Original_glrlm_RunVariance correlated with LNM and most differentially expressed long noncoding RNAs.

Variation in flavonoid and antioxidant activities of Pyrrosia petiolosa (Christ) Ching from different geographic origins.

Pyrrosia petiolosa (Christ) Ching has both medicinal and health benefits in China. The potential antioxidant activities of P. petiolosa, which are mainly attributed to its flavonoids, have attracted much attention in recent years. The present study aimed to determine the concentration of flavonoid components and evaluate the relative antioxidant activities of P. petiolosa from different geographic origins using a UPLC-MRM-MS-based metabolomics approach. In total, 97 flavonoid components were identified, and their concentrations in the samples from different geographic locations showed significant variation. Thirteen flavonoid components were identified as potential biomarkers for distinguishing between the two major regions, Guizhou (GZ) and Guangxi (GX). The GZ group showed higher total flavonoid content, free radical scavenging activities, and ferric reducing antioxidant power. The well positive correlations were found between the antioxidant capacities and some flavonoid markers. The ecogeographic factors, namely altitude and longitude, play a crucial role in the difference of antioxidant activities and flavonoids concentration. These results indicate that P. petiolosa is rich in flavonoid compounds and is a promising source of natural antioxidants, providing a basis for the quality control of P. petiolosa.

Autotoxicity in Panax notoginseng of root exudatesand their allelochemicals.

The growth of Panax notoginseng (Burk.) F. H. Chen is frequently hindered due to replanting failure. In the present study, the objective is to determine whether root exudates from P. notoginseng have autotoxicity and identification of allelochemicals from root exudates or rhizosphere soil. We investigated autotoxicity in P. notoginseng using seedling emergence bioassays and hydroponic culture. The allelochemicals in the soils and root exudates were identified with GC-MS, and the autotoxicity of the identified key allelochemicals was investigated by bioassay. The results showed that the root exudates, and extracts from consecutively cultivated soils also showed significant autotoxicity against seedling emergence and growth. In the non-renewed culture solution without activated charcoal (AC), the fresh and dry mass of P. notoginseng tubers of roots was reduced by about half compared to the addition with AC. A total of 44 different components from all samples were defined by GC-MS analyses. Furthermore, the results of multiple statistical analysis showed a t the difference among cultivated soil, uncultivated soil and root exudates. Bioassay of the identified allelochemicals revealed that benzoic acid, phthalic acid, palmitic acid, and stearic acid significantly affected the root growth of P. notoginseng. These substances at 100 µM more significantly decreased the number of lateral roots. Our results demonstrated that autotoxicity results in replant failure of P. notoginseng.

A Simple Optical Aerosol Sensing Method of Sauter Mean Diameter for Particulate Matter Monitoring.

Mass concentration is a commonly used but insufficient metric to evaluate the particulate matter (PM) exposure hazard. Recent studies have declared that small particles have more serious impacts on human health than big particles given the same mass concentration. However, state-of-the-art PM sensors cannot provide explicit information of the particle size for further analysis. In this work, we adopt Sauter mean diameter (SMD) as a key metric to reflect the particle size besides the mass concentration. To measure SMD, an effective optical sensing method and a proof-of-concept prototype sensor are proposed by using dual wavelengths technology. In the proposed method, a non-linear conversion model is developed to improve the SMD measurement accuracy for aerosol samples of different particle size distributions and reflective indices based on multiple scattering channels. In the experiment of Di-Ethyl-Hexyl-Sebacate (DEHS) aerosols, the outputs of our prototype sensor demonstrated a good agreement with existing laboratory reference instruments with maximum SMD measurement error down to 7.04%. Furthermore, the simplicity, feasibility and low-cost features of this new method present great potential for distributed PM monitoring, to support sophisticated human exposure hazard assessment.

Integration of transcriptome and targeted metabolome profiling reveals hormone related genes involved in the growth of Bletilla striata.

Bletilla striata (Thunb.) Reichb.f. (BS) is a traditional Chinese medicine with numerous beneficial effects. In our previous study, Aspergillus flavus was isolated from B. striata. To explore the physiological and molecular mechanisms of Aspergillus flavus elicitor (1-G4) that promoted Bletilla striata growth, in this study, we performed the determination of growth indexes and transcriptomics and metabolomics analysis under 5% and 10% 1-G4 conditions. Results showed that 1-G4 elicitor could significantly promote the growth and development of B. striata. With the increasing concentration of 1-G4 elicitor, the contents of SA, ICAld, and ME-IAA significantly increased while the IP and ACC contents decreased dramatically. A total of 1657 DEGs (763 up-regulated and 894 down-regulated) between the control (CK) and 5% elicitor (CK vs G5) and 2415 DEGs (1208 up-regulated and 1207 down-regulated) between the control and 10% elicitor (CK vs G10) were identified. Further, we found that 22, 38, and 2 unigenes were involved in ME-IAA, IP, and ACC, respectively. It was indicated that these unigenes might be involved in B. striata growth. Overall, the current study laid a theoretical foundation for the effective utilization of endophytic fungi and the optimization of germplasm resources of B. striata.

Genome-Wide Identification of R2R3-MYB Transcription Factors: Discovery of a "Dual-Function" Regulator of Gypenoside and Flavonol Biosynthesis in Gynostemma pentaphyllum.

The R2R3-MYB gene family participates in several plant physiological processes, especially the regulation of the biosynthesis of secondary metabolites. However, little is known about the functions of R2R3-MYB genes in Gynostemma pentaphyllum (G. pentaphyllum), a traditional Chinese medicinal herb that is an excellent source of gypenosides (a class of triterpenoid saponins) and flavonoids. In this study, a systematic genome-wide analysis of the R2R3-MYB gene family was performed using the recently sequenced G. pentaphyllum genome. In total, 87 R2R3-GpMYB genes were identified and subsequently divided into 32 subgroups based on phylogenetic analysis. The analysis was based on conserved exon-intron structures and motif compositions within the same subgroup. Collinearity analysis demonstrated that segmental duplication events were majorly responsible for the expansion of the R2R3-GpMYB gene family, and Ka/Ks analysis indicated that the majority of the duplicated R2R3-GpMYB genes underwent purifying selection. A combination of transcriptome analysis and quantitative reverse transcriptase-PCR (qRT-PCR) confirmed that Gynostemma pentaphyllum myeloblastosis 81 (GpMYB81) along with genes encoding gypenoside and flavonol biosynthetic enzymes exhibited similar expression patterns in different tissues and responses to methyl jasmonate (MeJA). Moreover, GpMYB81 could bind to the promoters of Gynostemma pentaphyllum farnesyl pyrophosphate synthase 1 (GpFPS1) and Gynostemma pentaphyllum chalcone synthase (GpCHS), the key structural genes of gypenoside and flavonol biosynthesis, respectively, and activate their expression. Altogether, this study highlights a novel transcriptional regulatory mechanism that suggests that GpMYB81 acts as a "dual-function" regulator of gypenoside and flavonol biosynthesis in G. pentaphyllum.