Regulatory Effects of Chlormequat Chloride on the Yield and Chemical Composition of Angelica sinensis Radix.

Chlormequat chloride (CCC), as a commonly used plant growth regulator in the production of rhizomatous medicinal herbs, can effectively control the bolting phenomenon in Angelica sinensis, significantly increasing the yield of underground rhizomes (medicinal part). However, its specific effects on the intrinsic quality of Angelica sinensis, especially medicinal components, require further investigation. The objective of this study is to conduct a thorough examination of CCC residue and its influence on the yield and medicinal components of Angelica sinensis. By spraying different concentrations of CCC on Angelica sinensis, we systematically monitored the final yield of Angelica sinensis Radix (ASR) in each treatment group and the residual concentration of CCC in ASR. Using UPLC-QTOF-MS technology, we conducted an in-depth analysis of the metabolic profile of ASR. Subsequently, UFLC-MS/MS was employed to accurately quantify the changes in the content of nine key active components in ASR. The results of this study indicate that the application of CCC significantly improves the yield of ASR, with the best effect observed at 0.1 g/L, resulting in a yield increase of 24.8%. Meanwhile, the residual amount of CCC in ASR is positively correlated with the application concentration, with the residual levels as high as 7.12 mg/kg in the high-concentration treatment group. Metabolomic analysis preliminarily identified 21 chemical components in ASR, including four organic acids and 13 phthalides. It is worth noting that the quantitative analysis results indicate significant changes in active components such as butylphthalide, Z-ligustilide, and ferulic acid after the application of CCC. Specifically, high-concentration CCC significantly increased the content of butylphthalide and levistolide A, while low-concentration CCC significantly promoted the accumulation of coniferyl ferulate and senkyunolide A, accompanied by a significant decrease in Z-ligustilide and ferulic acidy. In conclusion, while CCC use can increase yield, the associated increase in residues and imbalanced composition ratios may threaten the quality and safety of ASR. Therefore, it is crucial to control the amount of CCC used rationally to balance yield enhancement and quality assurance.

Selection of Reference Genes in Siraitia siamensis and Expression Patterns of Genes Involved in Mogrosides Biosynthesis.

Siraitia siamensis is a traditional Chinese medicinal herb. In this study, using S. siamensis cultivated in vitro, twelve candidate reference genes under various treatments were analyzed for their expression stability by using algorithms such as GeNorm, NormFinder, BestKeeper, Delta CT, and RefFinder. The selected reference genes were then used to characterize the gene expression of cucurbitadienol synthase, which is a rate-limiting enzyme for mogroside biosynthesis. The results showed that CDC6 and NCBP2 expression was the most stable across all treatments and are the best reference genes under the tested conditions. Utilizing the validated reference genes, we analyzed the expression profiles of genes related to the synthesis pathway of mogroside in S. siamensis in response to a range of abiotic stresses. The findings of this study provide clear standards for gene expression normalization in Siraitia plants and exploring the rationale behind differential gene expression related to mogroside synthesis pathways.

Structural insights into the catalytic selectivity of glycosyltransferase SgUGT94-289-3 towards mogrosides.

Mogrosides constitute a series of natural sweeteners extracted from Siraitia grosvenorii fruits. These mogrosides are glucosylated to different degrees, with mogroside V (M5) and siamenoside I (SIA) being two mogrosides with high intensities of sweetness. SgUGT94-289-3 constitutes a uridine diphosphate (UDP)-dependent glycosyltransferase (UGT) responsible for the biosynthesis of M5 and SIA, by continuously catalyzing glucosylation on mogroside IIe (M2E) and on the subsequent intermediate mogroside products. However, the mechanism of its promiscuous substrate recognition and multiple catalytic modes remains unclear. Here, we report multiple complex structures and the enzymatic characterization of the glycosyltransferase SgUGT94-289-3. We show that SgUGT94-289-3 adopts a dual-pocket organization in its active site, which allows the two structurally distinct reactive ends of mogrosides to be presented from different pockets to the active site for glucosylation reaction, thus enabling both substrate promiscuity and catalytic regioselectivity. We further identified a structural motif that is essential to catalytic activity and regioselectivity, and generated SgUGT94-289-3 mutants with greatly improved M5/SIA production from M2E in an in vitro one-pot setup.

Unveiling the Contamination Patterns of Neonicotinoid Insecticides: Detection, Distribution, and Risk Assessment in Panax notoginseng across Plant Parts.

This study analyzed neonicotinoid insecticides (NEOs) and metabolite (m-NEOs) residues in 136 Panax notoginseng samples via ultra-performance liquid chromatography-tandem mass spectrometry. Imidacloprid was the most detected NEO (88.24% of samples), ranging from 1.50 to 2850 µg/kg. To the best of our knowledge, some novel NEOs were detected in P. notoginseng for the first time. NEO clustering patterns varied among plant parts, with higher contamination in leaves and flowers. Fourteen NEO/m-NEOs, including cycloxaprid and acetamiprid, showed site-specific behavior, indicating the possibility of using multiple NEOs simultaneously during planting, resulting in formation of distinct metabolites in different plant parts. Transfer rates in decoction and infusion ranged from 10.06 to 32.33%, reducing residues postprocessing. Dietary risk assessment showed low hazard quotients (HQa: 7.05 × 10-7 to 2.09 × 10-2; HQc: 3.74 × 10-7 to 2.38 × 10-3), but risk-ranking scores indicated potential hazards with imidacloprid and acetamiprid in flowers and leaves. The findings are expected to promote safety assessment and distribution research of NEOs in plants.

Residue of Chlormequat and Regulatory Effects on the Specialized Metabolites of Astragali Radix.

Presently, the utilization of chlormequat in Astragalus mongholicus Bunge (Leguminosae) cultivation is prevalent for augmenting rhizome (Astragali Radix) yield. However, indiscriminate and excessive chlormequat employment can detrimentally influence Astragali Radix quality and safety. This research aimed to comprehensively comprehend chlormequat risks and its influence on Astragali Radix metabolites. Diverse chlormequat concentrations were employed in Astragalus mongholicus cultivation, with subsequent analysis of residual chlormequat levels in Astragali Radix across treatment groups. Astragali Radix metabolic profiling was conducted through UPLC-QTOF-MS, and thirteen principal active components were quantified via UFLC-MS/MS. Findings revealed a direct correlation between chlormequat residue levels in Astragali Radix and application concentration, with high-dose residue surpassing 5.0 mg/kg. Metabolomics analysis identified twenty-six distinct saponin and flavonoid metabolites. Notably, the application of chlormequat led to the upregulation of seven saponins (e.g., astragaloside I and II) and downregulation of six flavonoids (e.g., methylnissolin-3-O-glucoside and astraisoflavan-7-O-ß-d-glucoside). Quantitative analysis demonstrated variable contents of active ingredients due to differing chlormequat concentrations, leading to astragaloside I increase (14.59-62.55%) and isoastragaloside II increase (4.8-55.63%), while methylnissolin-3-O-glucoside decreased (22.18-41.69%), as did astraisoflavan-7-O-ß-d-glucoside (21.09-47.78%). In conclusion, chlormequat application influenced multiple active components in Astragali Radix, causing constituent proportion variations. Elevated chlormequat concentrations led to increased active components alongside heightened chlormequat residues in Astragali Radix. Consequently, prudent chlormequat application during Astragali Radix production is imperative to avert potential detriments to its quality and safety.

Synthesis of Crocin I and Crocin II by Multigene Stacking in Nicotiana benthamiana.

Crocins are a group of highly valuable water-soluble carotenoids that are reported to have many pharmacological activities, such as anticancer properties, and the potential for treating neurodegenerative diseases including Alzheimer's disease. Crocins are mainly biosynthesized in the stigmas of food-medicine herbs Crocus sativus L. and Gardenia jasminoides fruits. The distribution is narrow in nature and deficient in resources, which are scarce and expensive. Recently, the synthesis of metabolites in the heterologous host has opened up the potential for large-scale and sustainable production of crocins, especially for the main active compounds crocin I and crocin II. In this study, GjCCD4a, GjALDH2C3, GjUGT74F8, and GjUGT94E13 from G. jasminoides fruits were expressed in Nicotiana benthamiana. The highest total content of crocins in T1 generation tobacco can reach 78,362 ng/g FW (fresh weight) and the dry weight is expected to reach 1,058,945 ng/g DW (dry weight). Surprisingly, the primary effective constituents crocin I and crocin II can account for 99% of the total crocins in transgenic plants. The strategy mentioned here provides an alternative platform for the scale-up production of crocin I and crocin II in tobacco.

Advances in DNA methylation and demethylation in medicinal plants: a review.

DNA methylation and demethylation are widely acknowledged epigenetic phenomena which can cause heritable and phenotypic changes in functional genes without changing the DNA sequence. They can thus affect phenotype formation in medicinal plants. However, a comprehensive review of the literature summarizing current research trends in this field is lacking. Thus, this review aims to provide an up-to-date summary of current methods for the detection of 5-mC DNA methylation, identification and analysis of DNA methyltransferases and demethyltransferases, and regulation of DNA methylation in medicinal plants. The data showed that polyploidy and environmental changes can affect DNA methylation levels in medicinal plants. Changes in DNA methylation can thus regulate plant morphogenesis, growth and development, and formation of secondary metabolites. Future research is required to explore the mechanisms by which DNA methylation regulates the accumulation of secondary metabolites in medicinal plants.

Post-Ripening and Key Glycosyltransferase Catalysis to Promote Sweet Mogrosides Accumulation of Siraitia grosvenorii Fruits.

Sweet mogrosides are not only the primary bioactive ingredient in Siraitia grosvenorii fruits that exhibit anti-tussive properties and expectorate phlegm, but they are also responsible for the fruit's sweetness. Increasing the content or proportion of sweet mogrosides in Siraitia grosvenorii fruits is significant for improving their quality and industrial production. Post-ripening is an essential step in the post-harvest processing of Siraitia grosvenorii fruits, but the underlying mechanism and condition of post-ripening on Siraitia grosvenorii quality improvement need to be studied systematically. Therefore, this study analyzed the mogroside metabolism in Siraitia grosvenorii fruits under different post-ripening conditions. We further examined the catalytic activity of glycosyltransferase UGT94-289-3 in vitro. The results showed that the post-ripening process of fruits could catalyze the glycosylation of bitter-tasting mogroside IIE and III to form sweet mogrosides containing four to six glucose units. After ripening at 35 °C for two weeks, the content of mogroside V changed significantly, with a maximum increase of 80%, while the increase in mogroside VI was over twice its initial amount. Furthermore, under the suitable catalytic condition, UGT94-289-3 could efficiently convert the mogrosides with less than three glucose units into structurally diverse sweet mogrosides, i.e., with mogroside III as the substrate, 95% of it can converted into sweet mogrosides. These findings suggest that controlling the temperature and related catalytic conditions may activate UGT94-289-3 and promote the accumulation of sweet mogrosides. This study provides an effective method for improving the quality of Siraitia grosvenorii fruits and the accumulation of sweet mogrosides, as well as a new economical, green, and efficient method for producing sweet mogrosides.

Heterologous mogrosides biosynthesis in cucumber and tomato by genetic manipulation.

Mogrosides are widely used as high-value natural zero-calorie sweeteners that exhibit an array of biological activities and allow for vegetable flavour breeding by modern molecular biotechnology. In this study, we developed an In-fusion based gene stacking strategy for transgene stacking and a multi-gene vector harbouring 6 mogrosides biosynthesis genes and transformed it into Cucumis sativus and Lycopersicon esculentum. Here we show that transgenic cucumber can produce mogroside V and siamenoside I at 587 ng/g FW and 113 ng/g FW, respectively, and cultivated transgenic tomato with mogroside III. This study provides a strategy for vegetable flavour improvement, paving the way for heterologous biosynthesis of mogrosides.

Genome-Wide Identification and Expression Analysis of WRKY Transcription Factors in Siraitia siamensis.

WRKY transcription factors, as the largest gene family in higher plants, play an important role in various biological processes including growth and development, regulation of secondary metabolites, and stress response. In this study, we performed genome-wide identification and analysis of WRKY transcription factors in S. siamensis. A total of 59 SsWRKY genes were identified that were distributed on all 14 chromosomes, and these were classified into three major groups based on phylogenetic relationships. Each of these groups had similar conserved motifs and gene structures. We compared all the S. siamensis SsWRKY genes with WRKY genes identified from three diverse plant species, and the results implied that segmental duplication and tandem duplication play an important roles in the evolution processes of the WRKY gene family. Promoter region analysis revealed that SsWRKY genes included many cis-acting elements related to plant growth and development, phytohormone response, and both abiotic and biotic stress. Expression profiles originating from the transcriptome database showed expression patterns of these SsWRKY genes in four different tissues and revealed that most genes are expressed in plant roots. Fifteen SsWRKY genes with low-temperature response motifs were surveyed for their gene expression under cold stress, showing that most genes displayed continuous up-regulation during cold treatment. Our study provides a foundation for further study on the function and regulatory mechanism of the SsWRKY gene family.

Plant Metabolic Engineering by Multigene Stacking: Synthesis of Diverse Mogrosides.

Mogrosides are a group of health-promoting natural products that extracted from Siraitia grosvenorii fruit (Luo-han-guo or monk fruit), which exhibited a promising practical application in natural sweeteners and pharmaceutical development. However, the production of mogrosides is inadequate to meet the need worldwide, and uneconomical synthetic chemistry methods are not generally recommended for structural complexity. To address this issue, an in-fusion based gene stacking strategy (IGS) for multigene stacking has been developed to assemble 6 mogrosides synthase genes in pCAMBIA1300. Metabolic engineering of Nicotiana benthamiana and Arabidopsis thaliana to produce mogrosides from 2,3-oxidosqualene was carried out. Moreover, a validated HPLC-MS/MS method was used for the quantitative analysis of mogrosides in transgenic plants. Herein, engineered Arabidopsis thaliana produced siamenoside I ranging from 29.65 to 1036.96 ng/g FW, and the content of mogroside III at 202.75 ng/g FW, respectively. The production of mogroside III was from 148.30 to 252.73 ng/g FW, and mogroside II-E with concentration between 339.27 and 5663.55 ng/g FW in the engineered tobacco, respectively. This study provides information potentially applicable to develop a powerful and green toolkit for the production of mogrosides.

The spatiotemporal regulations of epicatechin biosynthesis under normal flowering and the continuous inflorescence removal treatment in Fagopyrum dibotrys.

BACKGROUND: Flowering is a critical physiological change that interferes with not only biomass yield but also secondary metabolism, such as the biosynthesis of flavonoids, in rhizome/root plants. The continuous inflorescence removal (CIR) treatment is frequently conducted to weaken this effect. Fagopyrum dibotrys (D.Don) H.Hara (Golden buckwheat) is a kind of rhizome medicinal plant rich in flavonoids and is widely used for the treatment of lung diseases. The CIR treatment is usually conducted in F. dibotrys because of its excessive reproductive growth. To uncover the molecular mechanisms, comprehensive analysis was performed using metabolome and transcriptome data obtained from normally bloomed and the CIR treated plants. RESULTS: Metabolome results demonstrated that in the rhizomes of F. dibotrys, its bioactive compound called epicatechin has higher amount than most of the detected precursors. Compared with the normally bloomed plants, the level of epicatechin in the rhizomes of the CIR group increased by 25% at the withering stage. Based on 96 samples of the control and the CIR groups at 4 flowering stages for 4 tissues, RNA-Seq results revealed a 3 ~ 5 times upregulations of all the key enzyme genes involved in the biosynthesis of epicatechin in both time (from the bud stage to the withering stage) and spatial dimensions (from the top of branch to rhizome) under the CIR treatment compared to normal flowering. Integrated analysis of LC-MS/MS and transcriptome revealed the key roles of several key enzyme genes besides anthocyanidin reductase (ANR). A total of 93 transcription factors were identified to co-expressed with the genes in epicatechin biosynthetic pathway. The flowering activator SQUAMOSA promoter-binding protein like (SPLs) exhibited opposite spatiotemporal expression patterns to that of the epicatechin pathway genes; SPL3 could significantly co-express with all the key enzyme genes rather than the flowering repressor DELLA. Weighted gene co-expression network analysis (WGCNA) further confirmed the correlations among chalcone synthases (CHSs), chalcone isomerases (CHIs), ANRs, SPLs and other transcription factors. CONCLUSIONS: SPL3 might dominantly mediate the effect of normal flowering and the CIR treatment on the biosynthesis of epicatechin in rhizomes mainly through the negative regulations of its key enzyme genes including CHS, CHI and ANR.

Heterologous Biosynthesis of Health-Promoting Baicalein in Lycopersicon esculentum.

Baicalein is a valuable flavonoid isolated from the medicinal plant Scutellaria baicalensis Georgi, which exhibits intensive biological activities, such as anticancer and antiviral activities. However, its production is limited in the root with low yield. In this study, In-Fusion and 2A peptide linker were developed to assemble SbCLL-7, SbCHI, SbCHS-2, SbFNSII-2 and SbCYP82D1.1 genes driven by the AtPD7, CaMV 35S and AtUBQ10 promoters with HSP, E9 and NOS terminators, and were used to engineer baicalein biosynthesis in transgenic tomato plants. The genetically modified tomato plants with this construct synthesized baicalein, ranging from 150 ng/g to 558 ng/g FW (fresh weight). Baicalein-fortified tomatoes have the potential to be health-promoting fresh vegetables and provide an alternative source of baicalein production, with great prospects for market application.

Genome-scale transcriptomic insights into the gene co-expression network of seed abortion in triploid Siraitia grosvenorii.

BACKGROUND: Siraitia grosvenorii (Swingle) C. Jeffrey, also known as Luohanguo or monk fruit, is a famous traditional Chinese medicine ingredient with important medicinal value and broad development prospects. Diploid S. grosvenorii has too many seeds, which will increase the utilization cost of active ingredients. Thus, studying the molecular mechanism of seed abortion in triploid S. grosvenorii, identifying the abortion-related genes, and regulating their expression will be a new direction to obtain seedless S. grosvenorii. Herein, we examined the submicroscopic structure of triploid S. grosvenorii seeds during abortion. RESULTS: Upon measuring the endogenous hormone content, we found that abscisic acid (ABA) and trans-zeatin (ZR) levels were significantly downregulated after days 15 and 20 of flowering. RNA sequencing of triploid seeds at different developmental stages was performed to identify key genes regulating abortion in triploid S. grosvenorii seeds. Multiple genes with differential expression between adjacent stages were identified; seven genes were differentially expressed across all stages. Weight gene co-expression network analysis revealed that the enhancement of monoterpene and terpene metabolic processes might lead to seed abortion by reducing the substrate flow to ABA and ZR. CONCLUSIONS: These findings provide insights into the gene-regulatory network of seed abortion in triploid S. grosvenorii from different perspectives, thereby facilitating the innovation of the breeding technology of S. grosvenorii.

Development of an efficient transient expression system for Siraitia grosvenorii fruit and functional characterization of two NADPH-cytochrome P450 reductases.

Siraitia grosvenorii (Luo hanguo or monk fruit) is a valuable medicinal herb for which the market demand has increased dramatically worldwide. As promising natural sweeteners, mogrosides have received much attention from researchers because of their extremely high sweetness and lack of calories. Nevertheless, owing to the absence of genetic transformation methods, the molecular mechanisms underlying the regulation of mogroside biosynthesis have not yet been fully elucidated. Therefore, an effective method for gene function analysis needs to be developed for S. grosvenorii fruit. As a powerful approach, transient expression has become a versatile method to elucidate the biological functions of genes and proteins in various plant species. In this study, PBI121 with a ß-glucuronidase (GUS) marker and tobacco rattle virus (TRV) were used as vectors for overexpression and silencing, respectively, of the SgCPR1 and SgCPR2 genes in S. grosvenorii fruit. The effectiveness of transient expression was validated by GUS staining in S. grosvenorii fruit, and the expression levels of SgCPR1 and SgCPR2 increased significantly after infiltration for 36 h. In addition, TRV-induced gene silencing suppressed the expression of SgCPR1 and SgCPR2 in S. grosvenorii fruit. More importantly, the production of the major secondary metabolites mogrol, mogroside IIE (MIIE) and mogroside III (MIII) was activated by the overexpression of SgCPR1 and SgCPR2 in S. grosvenorii fruit, with levels 1-2 times those in the control group. Moreover, the accumulation of mogrol, MIIE and MIII was decreased in the SgCPR1 and SgCPR2 gene silencing assays. Therefore, this transient expression approach was available for S. grosvenorii fruit, providing insight into the expression of the SgCPR1 and SgCPR2 genes involved in the mogroside biosynthesis pathway. Our study also suggests that this method has potential applications in the exploration of the molecular mechanisms, biochemical hypotheses and functional characteristics of S. grosvenorii genes.

An integrated strategy for evaluation of sulfur-fumigated edible herb Astragali Radix based on UPLC-MS/MS platforms and pharmacological analysis.

Astragali Radix is an edible herb that has been employed in Traditional Chinese medicine (TCM) and has recently been recognized by various countries; however, it is also one of the most extensively sulfur-fumigated TCM components. This study designed a UPLC-QTOF-MS/MS-guided isolation approach to generate sulfur-containing derivatives, and a novel sulfur-containing marker, namely, astragaloside sulfate, was characterized based on 1D and 2D NMR, which were derived from the main component of Astragali Radix, namely, astragaloside. Pharmacological experiments also showed that the activity of astragaloside decreased after it was converted into sulfate. Moreover, a rapid assay for the determination of astragaloside sulfate content by UPLC-QTRAP-MS/MS was established to evaluate samples that were non-fumigated and sulfur-fumigated at different levels. The method was applied to determine the content of JGS in the different batches of commercial samples. This research reveals that the practical procedure-based typical sulfur-containing indicator can be utilized for quality assurance of sulfur-fumigated and non-fumigated Astragali Radix.

[Application and safety evaluation of plant growth regulators in traditional Chinese medicine].

Plant growth regulator is a kind of synthetic pesticide with similar physiological activity to plant hormones. It has been widely used in grain, vegetables, fruits, flowers and other crops, and become an important technical guarantee for high yield, stable yield, high quality and efficient production of crops. In recent years, plant growth regulator is widely used in Chinese herbal medicine production for regulating the growth and development and increasing production of traditional. However the crop is different from general Chinese medicinal materials, the use of plant growth regulator should not only consider the effect of Chinese herbal medicine production, and also pay special attention to the influence of Chinese traditional medicine efficacy and safety. This paper reviewed the application of plant growth regulator in the traditional Chinese medicine, the impact on the quality and safety of Chinese medicinal materials, as well as plant growth regulator of residue limits standards and testing technology, so as to the scientific use of plant growth regulator, to promote Chinese standardization planting, provide the scientific basis to protect the safety of herbal medicine. At present, the indiscriminate use and abuse of plant growth regulators such as Zhuanggenling and bulking element are common in the production of Chinese crude drugs, which has led to a significant decline in the quality of some Chinese crude drugs, and resulted in the dual residual harm to the Chinese crude drugs and the cultivation environment, causing serious safety risks to human health. In the future, it is necessary to strengthen the registration management, use norms and limit standards of plant growth regulators in traditional Chinese medicinal materials, and strengthen the supervision and regulations on the use of fertilizer instead of medicine to avoid pesticide registration and other disorders, so as to provide a basis for the quality and safety monitoring of traditional Chinese medicinal materials. Simultaneously, it is encouraged to reduction or non-application of plant growth regulators in the production of Chinese medicinal materials, especially for traditional Chinese medicine which contains a variety of active ingredients. Therefore, it is actively advocated to cultivate Chinese medicinal materials through organic or ecological method.

Effects of Forchlorfenuron on the Morphology, Metabolite Accumulation, and Transcriptional Responses of Siraitia grosvenorii Fruit.

Siraitia grosvenorii fruit, called luo-han-guo (LHG), have been used as a traditional Chinese medicine (TCM) and dietary supplements for many years. Mogrosides, the main bioactive ingredients in LHG, are commercially available worldwide as a non-sugar-based and noncaloric sweetener. However, the production cannot meet the increasing market demand because of the low content of mogrosides and the small size of LHG. Therefore, some advanced technologies have been applied for improving the quality of LHG. Forchlorfenuron (CPPU), a plant growth regulator, is widely applied to promote plant yield and the secondary metabolite synthesis. Here, the content of nine mogrosides and three intermediates in LHG that were treated with three different concentrations of CPPU were determined by LC-MS/MS and GC-MS, respectively. The total content of mogrosides in LHG treated with CPPU was not enhanced, and the proportion of some main bioactive ingredients, including mogroside V (MV), were decreased relative to that of the control treatment. Morphological and cytological observations showed CPPU could make an early lignification in fruit epidermal cells, and 5 or 25 mg L-1 CPPU could inhibit LHG growth. The expression levels of 24 key genes in the mogroside biosynthesis pathway were measured and revealed that genes downregulated in upstream, and different expressions of SgUGTs would affect the accumulations and proportions of mogrosides in LHG induced by CPPU. This was the first study that applied CPPU individually on LHG, and assessed effects of CPPU on the morphology, the accumulation of metabolites, and expression profiles of 24 structural genes. The CPPU effects on LHG were undesirable, including development inhibition and the decrease of main mogroside content. These will provide guidance for the rational application of CPPU.

Residue of Paclobutrazol and Its Regulatory Effects on the Secondary Metabolites of Ophiopogon japonicas.

Currently, paclobutrazol is excessively used in the planting process of Ophiopogon japonicus (O. japonicus) due to its important role in regulating the growth of tuber roots, ultimately increasing the yield and shortening the growth cycle of Ophiopogonis Radix. For insight into this process and the potential risks of paclobutrazol and its mediated consequences on the secondary metabolites in Ophiopogonis Radix, corresponding high performance liquid chromatography-tandem mass spectrometric methods (HPLC-MS/MS) were developed in this study and then applied to Ophiopogonis Radix, soil, and water samples. The results demonstrated the detection of different levels of paclobutrazol residue were in Ophiopogonis Radix, soil, and water samples. In addition, the quantitative results of the secondary metabolites showed that paclobutrazol significantly decreased four steroidal saponins in Ophiopogonis Radix, especially ophiopogonin D, where the content was decreased from 824.87 to 172.50 mg/kg. Concurrently, ophiopogonanone C, a flavonoid in Ophiopogonis Radix, also significantly decreased from 2.66 to 1.33 mg/kg. In conclusion, the residual paclobutrazol and its negative regulation on the secondary metabolism of Ophiopogonis Radix brings potential hazards to the environment and human health. These results provide more comprehensive data that can be used for the reassessment of the use of paclobutrazol in O. japonicus and the formulation of related standards.

Multi-residue analysis of plant growth regulators and pesticides in traditional Chinese medicines by high-performance liquid chromatography coupled with tandem mass spectrometry.

A multi-residue method was developed for the simultaneous determination of 24 plant growth regulators (PGRs) and 11 representative pesticides that were widely applied in plants used in traditional Chinese medicines (TCMs) by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The method was validated taking into consideration EU guidelines; calibration curves for all of the targeted analytes showed correlation coefficients (γ2) higher than 0.9901. The limits of detection (LOD) ranged from 0.2 to 8 µg/kg. The average recovery for all analytes in spiked samples ranged from 63.18 to 127.23%, with a relative standard deviation of ≤ 15%. The proposed method has been applied to 480 batches of TCM samples, including 34 species of medicinal plants, from the TCM market. The results showed that 14 PGRs and 5 pesticides were detected, including choline chloride, chlormequat, paclobutrazol, uniconazole, phoxim, etc. Among them, there were high detection rates for chlormequat (40%), choline chloride (100%), atonik (73.75%), abscisic acid (80.83%), and indole-3-acetic acid (41.25%). The residual level of paclobutrazol in Ophiopogonis radix exceeded the recommended maximum residue limits (MRLs) according to GB 2763-2016. In addition, 14 agrochemicals used in TCM planting were collected and detected; the result showed various PGRs were detected in samples registered as fertilizer. These results indicate that PGRs and pesticides were widely used in the cultivation of medicinal plants, especially for radix and rhizome herbs. The residue of targeted PGRs and pesticides in TCM samples from this study have a high frequency and high level. Graphical abstract.