Metabolites In Medicinal Plants Research Articles

Drought stress induces biosynthesis of flavonoids in leaves and saikosaponins in roots of Bupleurum chinense DC

Drought stress affects vegetative and reproductive growth processes and synthesis of secondary metabolites in plants. We assessed relevant indicators of vegetative and reproductive growth in Bupleurum chinense DC. during drought stress. Samples were collected on days 4, 8, 12, 20, and 24 of a drought treatment according to drought stress severity in order to elucidate potential effects on synthesis of flavonoids in leaves and saikosaponins in roots of B. chinense. The results showed that B. chinense can adapt to drought stress mainly by increasing concentrations of osmoregulatory substances (soluble protein and proline) and increasing activity of protective enzymes (superoxide dismutase and catalase), as observed on days 12 and 20 of the treatment. Secondary metabolite concentrations in B. chinense roots and leaves showed significant differences—drought stress increased saikosaponin concentrations in roots by 9.85% and 6.41% during vegetative and reproductive growth, respectively, on day 20, and saikosaponin concentrations in roots were higher during vegetative growth than during reproductive growth. In leaves, large amounts of antioxidants were consumed owing to drought stress, which decreased leaf rutin concentrations by 38.79% and 30.11% during vegetative and reproductive growth, respectively, as observed on day 20; overall, leaf rutin concentrations were lower during vegetative growth than during reproductive growth. Changes in soil water content are known to affect synthesis of secondary metabolites in medicinal plants by altering gene transcription, and affected genes may synergistically respond to soil water changes and alter concentrations of flavonoid in leaves and of saikosaponin in roots. The gene F3H down-regulates flavonoid production in leaves. Squalene epoxidase and β-amyrin synthase genes may be key genes regulating saikosaponin accumulation, and changes in their expression corresponded to accumulation of saikosaponins. Our results provide insights in B. chinense adaptation to drought stress through physiological changes and regulation of secondary metabolite production in different plant tissues.

Improving productivity of steviol glycosides in Stevia rebaudiana via induced polyploidy

The polyploidy induction using mutagenic chemicals is one of the breeding approaches to improve enhancing productivity of yield and secondary metabolites in medicinal plants. In the present research, to induce polyploidy in Stevia rebaudiana plants, the seeds were treated with four concentrations of colchicine (control, 0.05%, 0.1% and 0.2%) for 12, 24, 36 and 48 h in a factorial experiment based on randomized complete block design with three replicates. The morphological and phytochemical traits of plants were measured before the flowering stage. The results indicated that different concentrations of colchicine had a significant effect on the plant height, number of leaves, number of branches, mean of leaf length, stomata size and stomata density. The exposure times of colchicine also caused significant changes in the plant height, number of branches, leaf width and length (P ≤ 0.01). Enhancement of colchicine concentration, significantly increased the above mentioned morphological traits, along with stomata size and rebaudioside-A, while significantly decreased stomata density in comparison to the control (P ≤ 0.01). In contrast, the interaction of colchicine concentration and exposure time had a significant effect on leaf length. The findings of this study indicated that estimation of physiological changes and secondary metabolites amount is one of the effective methods in primary screening of polyploid plants in polyploidisation breeding program and flow cytometry is recommended to be used for accurate identification of ploidy level in Stevia rebaudiana.

Effects of zinc oxide nanoelicitors on yield, secondary metabolites, zinc and iron absorption of Feverfew (Tanacetum parthenium (L.) Schultz Bip.)

Nanoelicitors are biological and non-biological factors that can affect the synthesis of secondary metabolites in medicinal plants. Feverfew is a valuable medicinal plant containing effective and important anti-cancer compounds (essential oil and parthenolide). This study was conducted to investigate the effects of zinc oxide nanoparticles (ZnONPs) on yield, metabolites content, and zinc and iron absorption of Feverfew. After seed preparation, seedling production, soil physicochemical properties analysis, ZnONPs treatments, maintenance and harvesting at full flowering stage, morphological traits and yield components were measured. The essential oil was extracted by Clevenger and parthenolide was identified by UPLC-MRM-MS. The content of Zn and Fe were measured by OES-ICP. The effects of ZnONPs were significant on all morpho-phytochemical traits. An increased biological yield (dry weight) was observed at 2000 ppm ZnONPs (32.54 g/day) compared to control (28.09 g/day). The highest (0.9% V/W) and lowest (0.56% V/W) content of essential oil were related to 1000 ppm ZnONPs and control. The content of parthenolide decreased at different levels of ZnONPs. The lowest (36.83 mg/kg DW) and highest (266.02 mg/kg DW) rates of Zn absorption were observed in control and 2000 ppm ZnONPs. Nanoparticles at all concentrations increased the biological yield, essential oil content, and Zn absorption. None of the ZnONPs concentrations improved the flower yield. Along with increasing ZnONPs and Zn uptake, parthenolide levels decreased. Also, it was determined that there was an antagonistic effect between Zn and Fe absorption.

Engineered ZnO and CuO Nanoparticles Ameliorate Morphological and Biochemical Response in Tissue Culture Regenerants of Candyleaf (Stevia rebaudiana).

Sustainable production of secondary metabolites in medicinal plants by artificial culturing on the industrial scale has gained worldwide importance. Engineered nanoparticles (ENPs) play a pivotal role in the elicitation of compounds of medicinal value. This investigation explores the influence of ZnO and CuO ENPs on in vitro roots formation, non-enzymatic antioxidant activities, and production of steviol glycosides (SGs) in regenerants of Candyleaf, Stevia rebaudiana. ENPs were applied in 0, 2, 20, 200, and 2000 mg/L of concentration in the MS medium containing plant shoots. The percentage of rooting induced was 91% and 94% by applying ZnO ENPs (2 mg/L) and CuO ENPs (20 mg/L), respectively. Moreover, at 2 mg/L of ZnO and 20 mg/L of CuO ENPs, the high performance liquid chromatography studies determined the significantly greatest content of SGs; rebaudioside A (4.42 and 4.44) and stevioside (1.28 and 1.96). Phytochemical studies including total flavonoid content, total phenolic content, and 2,2-diphenyl-1-picryl hydrazyl-free radical scavenging activity were calculated highest by the regenerants grown in 2 mg/L of ZnO and 20 mg/L of CuO ENPs dosage. Both ZnO and CuO ENPs at 200 mg/L and 2000 mg/L of concentration induced adverse effects on plant biomass, antioxidant activities, and SGs content up to 1.22 and 1.77 for rebaudioside A and 0.21 and 0.25 for stevioside. Hence, the biochemical and morphophysiological responses of Candyleaf were elicited as a defense against ZnO and CuO ENPs applied under threshold limit. This artificial biotechnological technique holds great promise for continued production of natural antioxidants on commercial scale and our study has further strengthened this impact.

Application of MALDI-mass spectrometry imaging in spatial distribution of secondary metabolites in medicinal plants -- a case study of Lepdium meyenii root

Matrix-assisted laser desorption/ionization mass spectrometry imaging(MALDI-MSI) is a novel technique for in-situ distribution of various substances in tissue without labeling. This technique is increasingly applied to the study of medicinal plants owing to its high spatial resolution and its potential of in-situ analysis in small molecules. In this study, the structural information and their fragmentation patterns of the midazole alkaloids(1,3-dibenzyl-4,5-dimethylimidazolium chloride and 1,3-dibenzyl-2,4,5-trimethylimi-dazolium chloride) and benzylglucosinolate in the medicinal plant Maca(Lepdium meyeni) root were analyzed by ultra-high-performance liquid phase combined with LTQ-Orbitrap mass spectrometry(UHPLC-HR-MS). The localization of these active ingredients in the cross-sections of Maca root was performed by MALDI-MSI. These results demonstrated that the two types of imidazole alkaloids had a similar distributed pattern. They were located more in the cortex and the periderm than those in the medulla of a lateral root, while the localization of benzylglucosinolate was concentrated in the center of the root rather than in the cortex and the periderm. The precise spatial distribution of various secondary metabolites in tissue provides an important scientific basis for the accumulation of medicinal plant active ingredients in tissues. In addition, this imaging method is a promising technique for the rapid evaluation and identification of the active ingredients of traditional Chinese medicine in plant tissues, as well as assisting the research on the processing of medicinal plants.

Effect of ecological factors on the accumulation of phenolic compounds in Iris species from Latvia, Lithuania and Ukraine.

It is important to conduct studies on the influence of environmental factors on the accumulation of secondary metabolites in plants, as well as the cultivation of plants and harvesting of their raw material. In this study, we examined the influence of habitat types, soil composition, climatic factors and altitude on the content of phenolic compounds in Iris species from different populations in Latvia, Lithuania and Ukraine. According to high-performance liquid chromatography (HPLC) analysis, 25 compounds (flavonoids, isoflavonoids, isoflavonoid glucosides, xanthones, phenolcarboxylic acids) were identified in the methanol extracts of 16 samples of Iris rhizomes. The quantitative data were further analysed by principal component analysis (PCA) to reveal the impact of environmental factors on the accumulation of compounds in plants. Iris pseudacorus from Latvia and Lithuania had a more diverse composition of phenolic compounds than samples from Ukraine. Sampled plants of the Iris subg. Iris had a higher content of the analysed compounds than those of Iris subg. Limniris. PCA results showed that the levels of phenolic compounds in Iris rhizomes were influenced by the content of soil nutrients. The phosphorus and potassium content had a significant impact on the levels of phenolic compounds, whereas the impact of nitrogen content was not significant. Meteorological factors had a small impact; however, sunshine duration had a significant positive effect and the amount of precipitation had a significant negative impact. The results of this study suggest that rhizomes of Iris species may be an important source of pharmacologically active compounds such as flavonoids, isoflavonoids and xanthones. Studies on the effect of environmental factors on the production and accumulation of secondary metabolites in Iris species are important because they contribute to knowledge of quantitative parameters of secondary metabolites in medicinal plants and could be employed for the cultivation and harvesting of raw material for medicinal purposes.

Improving diosgenin production and its biosynthesis in Trigonella foenum-graecum L. hairy root cultures

Induction of hairy roots stemmed from Agrobacterium rhizogenes transformation, is a key step to reach mass production of secondary metabolites in medicinal plants. Accordingly, this study is aimed to investigate potential impact of different A. rhizogenes strains, including ATCC15834, R1000, A4 and C58, on diosgenin biosynthesis in high- “Boshruyeh” (23.8 mg/gDW) and low “Hamadan” (6.4 mg/gDW) diosgenin-producing genotypes of fenugreek. Interestingly, comparing the metabolite extracted from both leaves and hairy roots of these genotypes suggested that hairy roots are promising platform to produce scalable amount of diosgenin, producing 143.96 mg/gDW in high diosgenin producing hairy roots (A4-mediated hairy roots induction in “Boshruyeh” (BA4)), while 23.8 mg/gDW in high diosgenin producing genotype. Transcript abundance of 10 genes involved in diosgenin biosynthesis pathway as well as three rate-limiting genes; i.e 1-deoxy-D-xylulose-5-phosphate synthase (DXS), 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) and 4-hydroxy-3-methylbut-2-enyl diphosphate reductase, functioning in plastid 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway were measured. Comparison of the transcription and metabolite analysis revealed that the more expression of Δ24-reductase gene, the higher accumulation of diosgenin in the hairy roots. In high diosge nin producing hairy roots, the expression of Δ24-reductase gene were significantly up-regulated (8-folds). Moreover, integration of metabolite and transcript results revealed that A4 has a strong capacity in boosting diosgenin accumulation in the both genotypes. These results may lead to the next step in production of diosgenin in scalable and commercial levels.

Development of a Building Block Strategy to Target the Classification, Identification, and Metabolite Profiling of Oleanane Triterpenoids in Gymnema sylvestre Using UHPLC-qTOF/MS.

The major class of bioactive metabolites in Gymnema sylvestre, a popular Ayurvedic medicinal plant for the treatment of diabetes mellitus, is oleanane triterpenoids. In this study, a targeted, biosynthesis-inspired approach using UHPLC-qTOF/MS was implemented to elucidate the whole chemical profile of this plant for the standardization of the Vietnamese G. sylvestre variety. The known compounds were first determined to identify the building blocks of the biosynthetic intermediates and the construction rules for synthesizing oleanane triterpenoids in the plant. These blocks were recombined to build a virtual library of all reasonable compounds consistent with the deduced construction rules. Various techniques, including relative mass defect filtering, multiple key ion analysis, mass fragmentation analysis, and comparison with standard references, were applied to determine the presence of these predicted compounds. Conventional isolation and structure elucidation of six of the new compounds were carried out to identify the new building blocks and validate the assignments. Consequently, 119 peaks were quickly assigned to oleanane triterpenoids, and among them, 77 peaks were predicted to be new compounds based on their molecular formulas and mass fragmentation patterns. All the identified metabolites were then classified into different layers to analyze their logical relationships, and a multilayered chemical profile of the oleanane triterpenoids was constructed. This new approach is expected to be practical for characterizing structures of modular secondary metabolites, such as triterpenoid saponins, and for proposing biosynthetic relationships among compounds of the same class of metabolites in medicinal plants.

Phosphoproteomics Reveals the Biosynthesis of Secondary Metabolites in Catharanthus roseus under Ultraviolet-B Radiation.

Ultraviolet (UV)-B radiation acts as an elicitor to enhance the production of secondary metabolites in medicinal plants. To investigate the mechanisms, which lead to secondary metabolites in Catharanthus roseus under UVB radiation, a phosphoproteomic technique was used. ATP content increased in the leaves of C. roseus under UVB radiation. Phosphoproteins related to calcium such as calmodulin, calcium-dependent kinase, and heat shock proteins increased. Phosphoproteins related to protein synthesis/modification/degradation and signaling intensively changed. Metabolomic analysis indicated that the metabolites classified with pentoses, aromatic amino acids, and phenylpropanoids accumulated under UVB radiation. Phosphoproteomic and immunoblot analyses indicated that proteins related to glycolysis and the reactive-oxygen species scavenging system were changed under UVB radiation. These results suggest that UVB radiation activates the calcium-related pathway and reactive-oxygen species scavenging system in C. roseus. These changes lead to the upregulation of proteins, which are responsible for the redox reactions in secondary metabolism and are important for the accumulation of secondary metabolites in C. roseus under UVB radiation.

Defense potential of secondary metabolites in medicinal plants under UV-B stress

Ultraviolet-B (UV-B) radiation has, for many decades now, been widely studied with respect to its consequences on plant and animal health. Though according to NASA, the ozone hole is on its way to recovery, it will still be a considerable time before UV-B levels reach pre-industrial limits. Thus, for the present, excessive UV-B reaching the Earth is a cause for concern, and UV-B related human ailments are on the rise. Plants produce various secondary metabolites as one of the defense strategies under UV-B. They provide photoprotection via their UV-B screening effects and by quenching the reactive oxygen- and nitrogen species produced under UV-B influence. These properties of plant secondary metabolites (PSMs) are being increasingly recognized and made use of in sunscreens and cosmetics, and pharma- and nutraceuticals are gradually becoming a part of the regular diet. Secondary metabolites derived from medicinal plants (alkaloids, terpenoids, and phenolics) are a source of pharmaceuticals, nutraceuticals, as well as more rigorously tested and regulated drugs. These metabolites have been implicated in providing protection not only to plants under the influence of UV-B, but also to animals/animal cell lines, when the innate defenses in the latter are not adequate under UV-B-induced damage. The present review focuses on the defense potential of secondary metabolites derived from medicinal plants in both plants and animals. In plants, the concentrations of the alkaloids, terpenes/terpenoids, and phenolics have been discussed under UV-B irradiation as well as the fate of the genes and enzymes involved in their biosynthetic pathways. Their role in providing protection to animal models subjected to UV-B has been subsequently elucidated. Finally, we discuss the possible futuristic scenarios and implications for plant, animal, and human health pertaining to the defense potential of these secondary metabolites under UV-B radiation-mediated damages.

Low dose gamma radiation increases the biomass and ginsenoside content of callus and adventitious root cultures of wild ginseng (Panax ginseng Mayer)

Mountain ginseng (Panax ginseng Mayer) is known as the most valuable herb around the world. Several biotechnological tools have been developed to enhance the production of secondary metabolites in medicinal plants, especially mountain ginseng. Mutagenesis is used to create desirable mutations at the genetic level. Among several energy sources used in mutant breeding programs, gamma rays are considered the most common and efficient tool for mutagenesis. Gamma rays are preferred over other energy sources because of convenient operation, short cycle, and high mutation frequency. In this study, gamma rays were used to generate mutant adventitious root lines of P. ginseng with high biomass and ginsenoside content. Callus and adventitious root cultures of P. ginseng, which were in culture short-term (1 year) and long-term (20 years), were irradiated with various doses of gamma rays. Exposure to higher doses of gamma rays caused necrosis in long-term explants. Four mutant lines of adventitious roots were identified with unique RAPD markers using eight primers. The genetic similarity among mutant lines ranged from 0.67 to 0.96. We also analyzed the total ginsenoside content and levels of 12 individual ginsenosides using HPLC analysis. The total ginsenoside content was 4.2-fold higher in mutant lines than in the control. The mutant line 1G-20-19 showed the highest ginsenoside content compared with the untreated control and other mutant lines. Overall, mutant lines of adventitious roots by gamma ray treatments in this study represent good candidates for commercial production of ginsenosides.

Jasmonic acid serves as a signal role in smoke-isolated butenolide-induced tanshinones biosynthesis in Salvia miltiorrhiza hairy root

Although smoke-water (SW) and butenolide (KAR1) isolated from smoke show stimulating effects on the production of secondary metabolites in medicinal plants, the underlying mechanisms are not well understood. This study was initiated to investigate the signal molecule in the KAR1-induced tanshinones biosynthesis in Salvia miltiorrhiza hairy root. KAR1 treatment resulted in substantial improvement in the accumulation of jasmonic acid (JA), followed by an increase in lipophilic tanshinones production in S. miltiorrhiza hairy root. Treatment of external JA stimulated the biosynthesis of tanshinones without KAR1 treatment. KAR1-stimulated tanshinones biosynthesis was inhibited with the treatment of SHAM and PrGall, which are JA synthesis inhibitors. This study indicated that JA serves as a role in the signal transduction involved in KAR1-stimulated tanshinones biosynthesis in the S. miltiorrhiza.

Modular organization analysis of specific naringin/neoeriocitrin related gene expression induced by UVC irradiation in Drynaria roosii

Drynaria roosii is a traditional medicinal fern, whose rhizome is particularly valued for its effective flavonoid components of naringin/neoeriocitrin. UV irradiation can induce flavonoid accumulation in plants, however the molecular mechanism of UVC-mediated naringin/neoeriocitrin synthesis in D. roosii has never been reported. Our HPLC-tandem mass spectrometry (MS/MS) results showed that UVC irradiation increased naringin/neoeriocitrin contents (NNCs) based on irradiation dosage in D. roosii. According to the NGS data, DEG-based heat map analysis revealed up-regulation of naringin/neoeriocitrin synthetic genes was more obvious in 12h UVC irradiation (UV dose = 81.648 kJ m−2) when compared with 24h (UV dose = 163.296 kJ m−2), especially for PAL, C3’H and HCT in old rhizomes. Through systems biology method of modular organization analysis, we clustered 15,678 DEGs into 19 modules, and calculated correlation coefficients between modules and samples, as well as modules and NNCs. Four significant naringin-related modules were achieved and displayed high correlations with specific samples. Moreover, weighted gene co-expression network analysis results discovered that 4CL, CHS and HCT, C3H acted as the hub responsive genes to UVC irradiation involved in naringin and neoeriocitrin synthesis respectively, and presented high co-expression with MYB/bHLH-regulated DEGs. Overall, we demonstrated that UVC irradiation up-regulated the naringin/neoeriocitrin related gene expression in separate new and old rhizomes to enhance NNCs in a dose-dependent manner. Hormetic UVC dose ranges improving NNCs in D. roosii were established for the first time. Our work also provided new insights into the study of secondary metabolites in medicinal plants.

An investigation of the HMGR gene and IPI gene expression in black caraway (Bunium persicum).

Black caraway is of great importance for its terpene compounds. Many genes are involved in the biosynthesis of secondary metabolites in medicinal plants. For this study, black caraway seeds were collected from five different regions, i.e. [Isfahan; Kerman (Khabr); Semnan; Kerman (Sirch); and Hormozgan]. The black caraway seed oil was extracted and analyzed by means of the gas chromatography method. There was a negatively significant correlation (p ≤ 0.05) observed between cuminaldehyde and gammaterpinene compounds. 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) and isopentenyl pyrophosphate isomerase (IPI) play an important role in the biosynthesis of secondary metabolites. Appropriate primers were designed for these genes based on the conserved regions in other plants. Amplified fragments were then sequenced. Blastn results indicated the similarity of the high RNA sequences between new sequences and other HMGR and IPI gene sequences in GenBank, and it also identified the HMGR and IPI gene sequences of B. persicum. A fragment of the HMGR gene with KJ143741 number was recorded in the gene bank. Quantitative PCR showed that the relative expression of two genes in different growth stages of B. persicum was significantly different between the germination stage and the multi-leaf stage, and also between the germination stage and the flowering stage (p < 0.05); however, there was no significant difference observed between the flowering stage and the multi-leaf stage. The results indicated that the expression of HMGR increased from the germination stage to the adult plant, and then it got stable until the flowering stage; in the same vein, the expression of IPI increased continuously from the germination stage to the flowering stage. The expression of HMGR and IPI genes occurred differently at the germination stage of five ecotypes. The Hormozgan ecotype showed the least expression rate.

Synthesis and regulation of secondary metabolites by microRNA in medicinal plants

miRNA (microRNA) is a kind of important endogenous non-coding small RNA, which mainly regulates the expression of target gene at the post-transcriptional level by splicing and translation inhibition and it plays an important role in the synthesis of plant secondary metabolites, especially for medicinal plants, the secondary metabolites are mostly active ingredients, which are the basis of medicinal effects. It is of great significance to study the biosynthetic pathways and complex regulatory networks of secondary metabolites of medicinal plants.This review introduces the miRNAs related to the synthesis of secondary metabolites in medicinal plants,which focuses on effects of miRNAs on biosynthesis of terpenoids, alkaloids and flavonoids,aiming to provide new ideas for biosynthesis and regulation of secondary metabolites of medicinal plants.

Evaluation of Manganese Chloride's Effect on Biosynthetic Properties of In Vitro Cultures of Eschscholzia californica Cham.

The basal production of secondary metabolites in medicinal plants is limited. One of the effective approaches that encourages plants to produce a remarkable amount of precious compounds is an application of elicitors. Our work was focused on the elicitation of Eschscholzia californica Cham. suspension cultures using various concentrations of MnCl2 (5; 10; 15 mg/L) with the aim of evaluating its effect on sanguinarine, chelerythrine, and macarpine production and gene expression of enzymes involved in the biosynthesis of mentioned secondary metabolites (BBE, 4′-OMT, CYP80B1) or in defense processes (LOX). Suspension cultures were exposed to elicitor for 24, 48, and 72 h. The content of alkaloids in phytomass was determined on the basis of their fluorescence properties. The relative mRNA expression of selected genes was analyzed using the ΔΔCt value method. PCR products were evaluated by melting curve analysis to confirm the specific amplification. Our results demonstrated that Eschscholzia californica Cham. cell suspension cultures evince sensitivity to the presence of MnCl2 in growth media resulting in the increased production of benzophenanthridine alkaloids and gene expression of selected enzymes. Manganese chloride seems to be a potential elicitor supporting natural biosynthetic properties in plant cell cultures and can be applied for the sustained production of valuable secondary metabolites.

Effects of simulated microgravity on seed germination, growth, development and accumulated secondary compounds of Hibiscus sagittifolius Kurz. cultured in vitro

In the present study, Hibiscus sagittifolius Kurz. seeds were used as the plant materials for studying on the effects of simulated microgravity (on a 2D clinostat) on seed germination, shoot multiplication, growth, development and secondary metabolite accumulation. After surface sterilization, seeds were cultured on MS medium supplemeted with 30 g/l sucrose and 9 g/l agar in Petri dishes (9 seeds per dish, the seed to seed distance of 1.5 cm and kept in the same direction), and maintained in a Clinostat (2 rpm). The results showed that simulated microgravity inhibited the growth and development of Hibiscus sagittifolius roots with root length of 11.83 cm, fresh and dry weight of 58.28 and 5.23 mg, respectively but it made an increase in germination rate (87%) and accumulation of secondary metabolites (the total saponins content of 53.00 mg/g and the total coumarin content of 25.67 mg/g) after 3 weeks of culture. In addition, the simulated microgravity also resulted in positive shoot multiplication (shoot height of 3.07 cm, 6.33 nodes per shoot, 3.33 shoots per explant, and the fresh and dry weight of 401.33 and 37.00 mg, respectively), and growth and development of Hibiscus sagittifolius shoots (plant height of 12.17 cm with 5.67 leaves per shoot together with the average root length of 1.77 cm, and the fresh and dry weight of 419.00 and 36.00 mg) after 4 weeks of culture. The results from this study could be attributed to future perspectives in research on plant breeding and accumulation of secondary metabolites in medicinal plants.

Blue light decreases tanshinone IIA content in Salvia miltiorrhiza hairy roots via genes regulation

The effect of light-emitting diodes (LEDs) on the production of secondary metabolites in medicinal plants and hairy roots is receiving much attention. The roots and rhizomes of the traditional Chinese medicinal plant Salvia miltiorrhiza Bunge are widely used for treating cardiovascular and cerebrovascular diseases. The main components are liposoluble tanshinones and hydrophilic phenolic acids. Moreover, hairy root culture of S. miltiorrhiza has been used in research of valuable plant-derived secondary metabolites. In this study, we examined the effect of LEDs with different combinations of wavelengths on the content of the main components in hairy roots of S. miltiorrhiza. Tanshinone IIA (TSIIA) content in hairy roots was significantly decreased with all light treatments containing blue light by >60% and was 9 times lower with LED treatment duration changed from 1 week to 3 weeks. HMGR, DXS2, DXR, GGPPS, CPS and CYP76AH1 genes involved in the tanshinone biosynthesis pathway were downregulated by blue light. Furthermore, light quality treatments have different effect on the accumulation of phenolic acids in hairy roots of S. miltiorrhiza. The light treatments 6R3B, 6B3IR, 7RGB and 2R6BUV for 3 weeks could increase rosmarinic acid (RA) content slightly but not salvianolic acid B (SAB) content. Different secondary metabolite contents could be regulated by different wavelength combinations of LEDs. Blue light could reduce TSIIA content in hairy roots of S. miltiorrhiza via gene regulation.

Perspective: functional genomics towards new biotechnology in medicinal plants

The secret of chemical diversity and function of specialized metabolites in medicinal plants will be unveiled by study of functional genomics at an unprecedentedly rapid rate in the coming years. This is mostly ascribed to the remarkable advancement in the high-throughput DNA sequencing together with other omics technologies such as metabolomics, in particular, due to drastic reduction in the cost of acquiring, storing and analyzing massive omics datasets. Once the genes involved in a biosynthetic pathway of specialized compounds in plants are elucidated, synthetic biology or genome editing can be applied to produce the target compounds in an engineered organism or to manipulate the pathway in planta. Coupled with these advancements in pathway elucidation approaches, modern plant biotechnology strategies are bound to significantly contribute to the sustainable development goals set by United Nations.

Chemotaxonomic variation in secondary metabolites contents and their correlation between environmental factors in Salvia miltiorrhiza Bunge from natural habitat of China

Phytogeographical variation has an impact on up/down regulation of secondary metabolites in medicinal plants. In this context, present study analyzed the influence of environmental factors on secondary metabolites in Salvia miltiorrhiza from natural habitat of China with different topographical conditions. The chemotypic variation was further correlated with climatic factors than micronutrients in the soil. The data revealed that tanshinones were more likely to be influenced by changes in ecological factors compared with phenolic acids. Tanshinone content was positively correlated with annual sunshine duration (correlation coefficients ranged from 0.379 to 0.730, P < 0.01 or 0.05), but negatively correlated with annual mean temperature (correlation coefficients ranged from −0.358 to −0.718, P < 0.01 or 0.05) and annual average precipitation (correlation coefficients ranged from −0.425 to −0.679, P < 0.01); the opposite situation was found in salvianolic acid B (correlation coefficients were −0.137, 0.084, 0.19), caffeic acid (correlation coefficients were −0.336, 0.246, 0.216, P < 0.05) and rosmarinic acid (correlation coefficients were −0.518, 0.475, 0.493, P < 0.01). Among the micronutrients, soil concentrations of Ba, Al and Mg exhibit the positive correlation with tanshinone content, but Pb exhibit the negative correlation with tanshinone content. Total N and K presented positive effects on most of phenolic acids. Ba showed significant negative and direct effects on salvianolic acid B (correlation coefficient was −0.281) and Rosmarinic acid (correlation coefficient was −0.367, P < 0.05). Therefore, the elite chemotype of S. miltiorrhiza identified among the collected samples express the correlation of phyto-geographical condition on the quantity of industrially viable metabolites, tashinones and phenolic acids. This aids in site specific exploration of high metabolite yielding samples to meet out the commercial demands and, promote the agriculture practices of this industrial crop for societal upliftment in area having similar phytogeographical locations.