Phenylpropanoid pathway in plants and its role in response to heavy metal stress: a review / 生物工程学报

Phenylpropanoid metabolic pathway is one of the most important secondary metabolic pathways in plants. It directly or indirectly plays an antioxidant role in plant resistance to heavy metal stress, and can improve the absorption and stress tolerance of plants to heavy metal ions. In this paper, the core reactions and key enzymes of the phenylpropanoid metabolic pathway were summarized, and the biosynthetic processes of key metabolites such as lignin, flavonoids and proanthocyanidins and relevant mechanisms were analyzed. Based on this, the mechanisms of key products of phenylpropanoid metabolic pathway in response to heavy metal stress were discussed. The perspectives on the involvement of phenylpropanoid metabolism in plant defense against heavy metal stress provides a theoretical basis for improving the phytoremediation efficiency of heavy metal polluted environment.

Germacrene-derived sesquiterpene lactones:opportunities and challenges for biosynthesis / 中国中药杂志

Sesquiterpene lactones are a kind of widely distributed natural organic compounds with anti-tumor, anti-malarial and other significant biological activities. Based on their carbocylic skeletons, sesquiterpene lactones are classified into germacranolide, guaia-nolide, xanthanolide, pseudo-guaianolide, elemonolide and eudesmanolide, etc. In recent years, with the development of various omics and synthetic biology technologies, the biosynthetic pathways of sesquiterpene lactone compounds of different structural types have gradually been resolved. Among them, the researches on germacrene-derived sesquiterpene lactones are relatively more than others. Therefore, this article focused on the germacrene-derived sesquiterpene lactone biosynthesis pathways and their key enzyme genes, which can lay the foundation for in-depth analysis of sesquiterpene lactone biosynthetic pathways, functional gene mining and heterologous synthesis of active ingredients.

Pathway design and key enzyme analysis of diosgenin biosynthesis / 生物工程学报

As a naturally occurring steroid sapogenin, diosgenin acts as the precursor of hundreds of steroid medicines, and thereby has important medicinal value. Currently, industrial production of diosgenin relies primarily on chemical extraction from plant materials. Clearly, this strategy shows drawbacks of excessive reliance on plant materials and farmland as well as environment pollution. Due to development of metabolic engineering and synthetic biology, bio-production of diosgenin has garnered plenty of attention. Although the biosynthetic pathways of diosgenin have not been completely identified, in this review, we outline the identified biosynthetic pathways and key enzymes. In particular, we suggest heterologous biosynthesis of diosgenin in Saccharomyces cerevisiae. Overall, this review aims to provide valuable insights for future complete biosynthesis of diosgenin.

Biosynthesis of Steroidal Saponins in Herbs / 中国实验方剂学杂志

Steroidal saponins are efficacious substances wildly existed in the herbs，and consist of glycosyl and steroid sapogenin. The biosynthesis pathways of steroidal saponins mainly include the cytosolic mevalonate （MVA） pathway and the plastidial methylerythritol 4-phosphate （MEP） pathway，with the MVA pathway as the main pathway. The key enzymes are involved in the biosynthetic pathway, including 3-hydroxy-3-methyl glutaryl coenzyme A reductase（HMGR），1-deoxy-D-xylulose 5-phosphate synthase（DXS），1-deoxy-D-xylulose-5-phosphatereduetoisomerase（DXR），farnesyl pyrophosphate synthase（FPS），squalene synthase（SS），squalene epoxidase（SE），cycloartenol synthase（CAS），cytochrome P450（CYP450），and steroidalglycosyltransferase（SGTase）. In the paper，the biosynthesis roadmap of steroidal saponins was optimized based on previous studies. According to a comprehensive analysis on studies of key enzymes for the past five years, genes, like HMGR，SS，CYP450 and UGT，were studied more，while other genes，like FPS，SE，CAS，were known less. In conclusion， current studies still focus on the primary stage，but lack direct evidence for the roles of key enzymes. This paper would provide a reference and theoretical support for subsequent studies.

Effects of copper stress on accumulation of three medicinal compositions and expression of two key enzyme genes in biosynthesis of Atractylodes lancea / 中草药

Objective: To explore the effect on the accumulation of medicinal compositions β-eudesmol, atractylon, atractylodin and key enzyme genes 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) and farnesyl pyrophosphate synthase (FPPS) expression in biosynthesis of Atractylodes lancea under copper stress. Methods: Under copper stress, the expression of key enzyme genes HMGR and FPPS in A. lancea was determined by real-time fluorescence quantitative PCR; the content of three medicinal components in A. lancea were determined by HPLC; The correlation analysis was performed with SPSS, and DPS software for grey correlation analysis. Results: When the copper stress concentration was within 100 mg/kg, the expression of FPPS and the content of atractylon in the rhizomes of A. lancea increased slightly. However, when the copper concentration continued to increase, the expression levels of HMGR and FPPS and three medicinal components content of A. lancea showed a different degrees of downward trend. The expression levels of HMGR and FPPS were positively correlated with the content of β-eudesmol, atractylon, and atractylodin (P < 0.05) under copper stress. Grey relational analysis showed that the content of β-eudesmol and atractylon in the rhizomes was significantly correlated with the expression of HMGR and FPPS of A. lancea under copper stress. The expression of FPPS gene had the larger contribution on the composition of β-eudesmol and atractylon. However, the correlation between the content of atractylodin and the expression of these two key enzyme genes was relatively small. Conclusion: This study clarified the change regulation of two key enzyme gene expression and the content of three medicinal compositions, and revealed the relationship between β-eudesmol, atractylon and HMGR and FPPS, the key enzymes in terpene biosynthesis of A. lancea under copper stress. It contributed to the further study of the molecular regulation mechanism of the synthesis of medicinal constituents under copper stress and provided a theoretical basis for improving the quality of A. lancea.

Research progress on pharmacological properties and monoterpenoid indole alkaloids biosynthetic pathway in plants of genus Rauvolfia / 中草药

Rauvolfia serpentine is a traditional Indian medicine and now the genus Rauvolfia becomes a commonly used south medicine in China. Rauvolfia is mainly used to treat hypertension, mental illness, cardiovascular disorders, cancer, and other diseases. The paper overviewed the main species and distribution, pharmacological properties, and the monoterpenoid indole alkaloids biosynthetic pathway of Rauvolfia in China. The paper aims to provide reference for research and clinical application in plants of the genus Rauvolfia.

Effect of Lanthanum on accumulation of active constituent and key enzymes expression of Salvia miltiorrhiza hairy root / 中国中药杂志

The effect of Lanthanum on the accumulation of active constituent and key enzymes expression of Salvia miltiorrhiza hairy root were studied and furthermore signaling molecules mediating the synthesis of secondary metabolism was also defined in order to provide references for the reveal of synthesis mechanism of active constituent of S. miltiorrhiza hairy root inducing by Lanthanum. The content of active constituents were detected by HPLC. RNA was extracted with RNA prep Pure RNA purification kit (Tiangen). The results shows that LaCl3 processing promoted the accumulation of tanshinones and phenolic acids in S. miltiorrhiza hairy root. The accumulation of phenolic acids reached the highest at 9 d after treatment, and tanshinones accumulation continued to increase in 15 days. Accumulation of active substance in S. miltiorrhiza may relate with FPPS, TAT, HPPR several key enzyme activation.

Effect on the expression of key enzymes DS and P450 genes in the medicinal composition synthesis of Panax notoginseng under Cadmium stress / 中草药

Objective: To learn the effect on the expression of key enzymes DS and P450 genes in the medicinal composition synthesis of Panax notoginseng under exogenous Cadmium (Cd). Methods: Nine treatments of Cd (0.0, 0.1, 0.3, 0.6, 1.0, 3.0, 6.0, 10.0, and 30.0 mg∙kg-1) was added to the cultivated soil of Panax notoginseng, respectively. Two years later, mature Panax notoginseng was sampled. The expression of DS and P450 genes in root was detected using qRT-PCR method, and GAPDH gene was taken as the reference genes to calculate the relative expression of DS and P450 genes. The correlation between expression of key enzymes genes and main medicinal composition (notoginsenoside R1, ginsenoside Rb1, ginsenoside Rg1, and total saponins) was determined by correlation analysis. Results: Cd increased DS expression in low concentration, and inhibited in high levels, while with the adding Cd increasing, the P450 expression decreased significantly. However, the expression of DS and P450 genes didn't show good correlation with notoginsenoside R1, ginsenoside Rb1, ginsenoside Rg1, and total saponins (P > 0.5). Conclusion: Cd can affect the expression of DS and P450 genes in different ways and for the same gene, the expression is also various in different Cd levels. However, the main medicinal composition content wasn't influenced consequently.

Effects of copper on biodegradation mechanism of trichloroethylene by mixed microorganisms / 生物工程学报

We isolated and enriched mixed microorganisms SWA1 from landfill cover soils supplemented with trichloroethylene (TCE). The microbial mixture could degrade TCE effectively under aerobic conditions. Then, we investigated the effect of copper ion (0 to 15 μmol/L) on TCE biodegradation. Results show that the maximum TCE degradation speed was 29.60 nmol/min with 95.75% degradation when copper ion was at 0.03 μmol/L. In addition, genes encoding key enzymes during biodegradation were analyzed by Real-time quantitative reverse transcription PCR (RT-qPCR). The relative expression abundance of pmoA gene (4.22E-03) and mmoX gene (9.30E-06) was the highest when copper ion was at 0.03 μmol/L. Finally, we also used MiSeq pyrosequencing to investigate the diversity of microbial community. Methylocystaceae that can co-metabolic degrade TCE were the dominant microorganisms; other microorganisms with the function of direct oxidation of TCE were also included in SWA1 and the microbial diversity decreased significantly along with increasing of copper ion concentration. Based on the above results, variation of copper ion concentration affected the composition of SWA1 and degradation mechanism of TCE. The degradation mechanism of TCE included co-metabolism degradation of methanotrophs and oxidation metabolism directly at copper ion of 0.03 μmol/L. When copper ion at 5 μmol/L (biodegradation was 84.75%), the degradation mechanism of TCE included direct-degradation and co-metabolism degradation of methanotrophs and microorganisms containing phenol hydroxylase. Therefore, biodegradation of TCE by microorganisms was a complicated process, the degradation mechanism included co-metabolism degradation of methanotrophs and bio-oxidation of non-methanotrophs.

Research progress on key enzymes involved in biosynthesis of tanshinone / 中草药

Tanshinone, a group of diterpene quinones from Salviae Miltiorrhizae Radix with strong physiological activities and broad pharmacological effects, is well known as an effective compound to cure cardiovascular and cerebrovascular diseases. Natural tanshinone is generated by complex biosynthetic pathway and Salvia miltiorrhiza is its main source. The increasing medical demand for tanshinone, however, can not be satisfied. The limited resource of S. miltiorrhiza and the low content of tanshinone may cause the poor yield of these compounds. This problem may be solved by regulating the key enzymes involved in the biosynthesis of tanshinone so as to elevate its content. This review summarized the research progress in the biosynthetic pathway of tanshinone and the key enzymes related to this process.

Research progress in key enzymes involved in biosynthesis of Panax notoginseng saponins and their regulation / 中草药

Panax notoginseng saponins (PNS), which belong to dammarane-type triterpenoid saponins, are the main active components of a precious Chinese materia medica (CMM) named Notoginseng Radix. PNS have better protective effects on the central nervous system, cardiovascular system, and immune system, and have been widely used in the treatment of diseases including fibrosis, aging, and neoplasm. This review summarized the research progress in the key enzymes involved in the biosynthesis of PNS, such as farnesyl pyrophaophate synthase (FPS), squalene synthase (SS), squalene oxidase (SE), dammarenediol-II synthase (DS), cycloartenol synthase (CAS), cytochrome P450 monooxygenases (CYP450), and glycosyltransferase (GT) in terms of catalytic mechanism, gene cloning, and expression regulation on the transcriptional level, as well as the specificity in expression patterns and expression tissues and organs. Meanwhile, the effects of polymorphism and environmental stress on the regulation of gene expression have been first summarized. This review provides a basis for artificial synthesis of PNS using metabolic engineering.

Research Advances on Triterpenoid Saponins Biosynthesis and Its Key Enzymes / 世界科学技术-中医药现代化

As an important kind of plant secondary metabolites and widely distributed in the plant kingdom, triter-penoid saponins have a variety of biological activities. The constitution and content of triterpenoid saponin are deter-mined by some key enzymes and their expressing level in triterpenoid saponins biosynthesis pathway. So, it is very important to illuminate the molecular mechanism of triterpenoid saponins biosynthetic pathway. In recent years, illu-mination of the entire biosynthetic pathway especially the confirmation and cloning of the key enzymes, such as squa-lene synthase, squalene epoxidase, cytochrome P450 monooxygenase and UDP-glycosyltransferase, had become one of the hot spots by many scholars. In this paper, the entire biosynthetic pathway and some kinds of key enzymes in-volved in the synthesis of carbon skeleton, and its oxidation, and glycation were reviewed for further demonstrating the biosynthetic pathway of triterpenoid saponins and providing a theoretical basis for artificial biosynthesis.

Progress in Ginsenosides Biosynthesis and Prospect of the Secondary Metabolic Engineering for the Production of Ginsenosides / 中国生物工程杂志

Ginsenosides,which belongs to triterpenoid saponins of plant terpenoids,are the main active components of the valuable medicinal herbs ginseng and American ginseng.Recent studies show that ginsenosides have a variety of beneficial effects,including anti-inflamatory,antioxidant,and anticancer effects.Ginsenosides are synthesized by complicated modification of triterpenoid skeleton after cyclization of 2,3-oxidosqualene through triterpene saponin synthesis pathway in which they share common early steps with phytosterols synthesis.It outlines recent advances for the biosynthesis of ginsenosides,the cloning and characterization of genes encoding key enzymes in the pathway and the basal framework of ginsenosides biosynthesis pathway.The prospects of secondary metabolism engineering in the biosynthesis of plant natural products and its application in ginsenosides biosynthesis are also discussed.