Stimulation of taxol production and excretion in Taxus spp cell cultures by rare earth chemical lanthanum

Lanthanum Significantly Contributes to the Growth of the Fine Roots' Morphology and Phosphorus Uptake Efficiency by Increasing the Yield and Quality of Glycyrrhiza uralensis Taproots

The occurrence of different degrees of phosphorus deficiency in the vast majority of G. uralensis cultivation regions worldwide is common. There is a pressing need within the cultivated G. uralensis industry to identify appropriate exogenous substances that can enhance the uptake of phosphorus and improve both the yield and quality of the taproots of G. uralensis. This study was conducted to investigate the fine root and taproot morphology, physiological characteristics, and secondary metabolite accumulation in response to the supply of varying concentrations of LaCl3 to G. uralensis, to determine the optimal concentration of LaCl3 that can effectively enhance the yield and quality of G. uralensis's taproots, while also alleviating its reliance on soil phosphate fertilizer. The findings indicate that the foliar application of lanthanum enhanced root activity and increased APase activity, eliciting alterations in the fine root morphology, leading to promoting the accumulation of biomass in grown G. uralensis when subjected to P-deficient conditions. Furthermore, it was observed that the nutrient uptake of G. uralensis was significantly improved when subjected to P-deficient conditions but treated with LaCl3. Additionally, the yield and quality of the medicinal organs of G. uralensis were significantly enhanced.

Molecular insights into rare earth element (REE)-mediated phytotoxicity and its impact on human health

Rare earth elements (REEs) that include 15 lanthanides, scandium, and yttrium are a special class of elements due to their remarkable qualities such as magnetism, corrosion resistance, luminescence, and electroconductivity. Over the last few decades, the implication of REEs in agriculture has increased substantially, which was driven by rare earth element (REE)-based fertilizers to increase crop growth and yield. REEs regulate different physiological processes by modulating the cellular Ca2+ level, chlorophyll activities, and photosynthetic rate, promote the protective role of cell membranes, and increase the plant's ability to withstand various stresses and other environmental factors. However, the use of REEs in agriculture is not always beneficial because REEs regulate plant growth and development in dose-dependent manner and excessive usage of them negatively affects plants and agricultural yield. Moreover, increasing applications of REEs together with technological advancement is also a rising concern as they adversely impact all living organisms and disturb different ecosystems. Several animals, plants, microbes, and aquatic and terrestrial organisms are subject to acute and long-term ecotoxicological impacts of various REEs. This concise overview of REEs' phytotoxic effects and implications on human health offers a context for continuing to sew fabric scraps to this incomplete quilt's many layers and colors. This review deals with the applications of REEs in different fields, specifically agriculture, the molecular basis of REE-mediated phytotoxicity, and the consequences for human health.

Determination of the Qualitative Composition of Biologically-Active Substances of Extracts of In Vitro Callus, Cell Suspension, and Root Cultures of the Medicinal Plant Rhodiola rosea

The results of the qualitative composition analysis of the dried biomass extracts of in vitro callus, cell suspension, and root cultures show that the main biologically active substances (BAS) in the medicinal plant, Rhodiola rosea, are 6-C-(1-(4-hydroxyphenyl)ethyl)aromadendrin (25 mg, yield 0.21%), 2-(3,7-dihydroxy-2-(2-hydroxypropan-2-yl)-2,3-dihydrobenzofuran-5-yl)-6,7-dihydroxychroman-4-one (23 mg, yield 0.2%), 2-(3,4-dimethoxyphenyl)-5,7-dimethoxychroman-4-one (175 mg, yield 1.5%), 5,7-dihydroxy-2-(4-hydroxy-3-(2-(4-hydroxyphenyl)-4-oxo-4H-chromen-6-yl)phenyl)-4H-chromen-4-one (45 mg, yield 0.5%), 5,6,7,8-tetrahydroxy-4-methoxyflavone (0.35 mg, 0.5%). BAS from the dried biomass extracts of in vitro callus, cell suspension, and root cultures of Rhodiola rosea will be used for the production of pharmaceuticals and dietary supplements with antitumor, antimicrobial, and antioxidant effects.

Lanthanum Prolongs Vase Life of Cut Tulip Flowers by Increasing Water Consumption and Concentrations of Sugars, Proteins and Chlorophylls

We evaluated the effect of separately adding two sources of lanthanum (La), LaCl₃ and La(NO₃)₃ × 6H₂O at a concentration of 40 µM each, to the preservative solution of 15 cut tulip flower varieties. Ascorbic acid (AsA; 0.2 g/L) was used as a reference solution, while distilled water was used as control. The variety Laura Fygi recorded the longest vase life with 13 days. The highest water consumption per gram of stem fresh biomass weight (FBW) (2.5 mL) was observed in the variety Violet Beauty, whereas the lowest (1.098 mL) was recorded in Pink Impression. At the end of the vase life period, higher concentrations of total soluble sugars in petals and total soluble proteins in leaves were recorded in La-treated stems, compared to the AsA treatment and the control. Additionally, La(NO₃)₃ × 6H₂O supply increased the fresh weight of stems in vase and prolonged vase life. Moreover, this treatment resulted in the highest foliar concentration of chlorophylls at the end of vase life. Therefore, La increases tulip flower vase life as a consequence of improving the concentrations of some vital biomolecules.

Hormetic dose responses induced by lanthanum in plants

Rare earth elements (REEs) have recently received particular attention due to their accumulation in the environment. Such heightened recognition prompted our evaluation of the possible occurrence of La-induced plant hormesis in the peer-reviewed literature. This study revealed 703 La-induced hormetic concentration/dose responses in plants, which were quantitatively and qualitatively assessed. The maximum (MAX) biological response to low La concentrations/doses is commonly below 150% of control response, with a geometric mean of 142% at 56 μM (geometric mean). The geometric mean concentration of the no-observed-adverse-effect-level (NOAEL) was 249 μM. The MAX:NOAEL distance was commonly below 5-fold, with a geometric mean of 4.5-fold. Hormetic concentration/dose responses varied as per the growth substrate pH, number of concentrations/doses below the NOAEL, and time window. These results provide a unique insight into the effects of low doses of La on plant growth, as well as offer means for improving experimental designs to assess low dose effects.

In vitro cultures of Linum usitatissimum L.: Synergistic effects of mineral nutrients and photoperiod regimes on growth and biosynthesis of lignans and neolignans

The multipurpose plant species Linum usitatissimum famous for producing linen fibre and containing valuable pharmacologically active polyphenols, has rarely been tested for it's in vitro biosynthesis potential of lignans and neolignans. The current study aims at the synergistic effects of mineral nutrients variation and different photoperiod treatments on growth kinetics and biomass accumulation in in vitro cultures of Linum usitatissimum. Both nutrient quality and quantity affected growth patterns, as cultures established on Gamborg B5 medium had comparatively long exponential phase compared to Murashige and Skoog medium, while growth was slow but steady until last phases of the culture on Schenk and Hildebrandt medium. Similarly, we observed that boron deficiency and nitrogen limitation in culture medium (Gamborg B5 medium) enhanced callus biomass (fresh weight 413 g/l and dry weight 20.7 g/l), phenolics production (667.60 mg/l), and lignan content (secoisolariciresinol diglucoside 6.33 and lariciresinol diglucoside 5.22 mg/g dry weight respectively) at 16/8 h light and dark-week 4, while that of neolignans (dehydrodiconiferyl alcohol glucoside 44.42 and guaiacylglycerol-β-coniferyl alcohol ether glucoside 9.26 mg/g dry weight, respectively) in continuous dark after 4th week of culture. Conversely, maximum flavonoids production occurred at both Murashige and Skoog, Schenk and Hildebrandt media (both media types contain comparatively higher boron and nitrogen content) in the presence of continuous light. Generally, continuous dark had no significant role in any growth associated parameter. This study opens new dimension for optimizing growing conditions and evaluating underlying mechanisms in biosynthesis of lignans and neolignans in in vitro cultures of Linum usitatissimum.

Metabolite profiles of callus and cell suspension cultures of mangosteen

Callus was induced from mangosteen (Garcinia mangostana L.) young purple-red leaves on Murashige and Skoog basal medium with various combinations of plant growth regulators. Murashige and Skoog medium with 4.44 µM 6-benzylaminopurine and 4.52 µM 2,4-dichlorophenoxyacetic acid was the best for friable callus induction. This friable callus was used for the initiation of cell suspension culture. The effects of different combinations of 6-benzylaminopurine and 2,4-dichlorophenoxyacetic acid, carbon sources and inoculum sizes were tested. It was found that combination of 2.22 µM 6-benzylaminopurine + 2.26 µM 2,4-dichlorophenoxyacetic acid, glucose (30 g/l) and 1.5 g/50 ml inoculum size was the best for cell growth. Callus and cell suspension cultures were then treated either with 100 µM methyl jasmonate as an elicitor for 5 days, or 0.5 g/l casein hydrolysate as an organic supplement for 7 days. Metabolites were then extracted and profiled using liquid chromatography-time of flight mass spectrometry. Multivariate discriminant analyses revealed significant metabolite differences (P ≤ 0.05) for callus and suspension cells treated either with methyl jasmonate or casein hydrolysate. Based on MS/MS data, methyl jasmonate stimulated the production of an alkaloid (thalsimine) and fatty acid (phosphatidyl ethanolamine) in suspension cells while in callus, an alkaloid (thiacremonone) and glucosinolate (7-methylthioheptanaldoxime) was produced. Meanwhile casein hydrolysate stimulated the production of alkaloids such as 3ß,6ß-dihydroxynortropane and cis-hinokiresinol and triterpenoids such as schidigerasaponin and talinumoside in suspension cells. This study provides evidence on the potential of secondary metabolite production from in vitro culture of mangosteen.

The rare earth element (REE) lanthanum (La) induces hormesis in plants

Lanthanum is a rare earth element (REE) which has been extensively studied due to its wide application in numerous fields with a potential accumulation in the environment. It has long been known for its potential to stimulate plant growth within a hormetic-biphasic dose response framework. This article provides evidence from a series of high resolution studies published within the last two decades demonstrating a substantial and significant occurrence of lanthanum-induced hormesis in plants. These findings suggest that hormetic responses should be built into the study design of hazard assessment study protocols and included in the risk assessment process. Hormesis also offers the opportunity to substantially improve cost benefit estimates for environmental contaminants, which have the potential to induce beneficial/desirable effects at low doses.

Chitosan mediated enhancement of hydrolysable tannin in Phyllanthus debilis Klein ex Willd via plant cell suspension culture

Phyllanthus debilis Klein ex Willd. is wild medicinal plant used in the traditional system of medicine. This plant has been actively used for hepatoprotection and to cure many diseases including jaundice and so on; which leads to complete extinction of this particular species. Therefore, the chitosan mediated cost effective cell suspension method has been developed for the production of hydrolysable tannin. The hydrolysable tannins are the main therapeutically active constituents with antioxidant, anticancer, and antimicrobial properties. An in vitro cell suspension culture was optimized by adding chitosan for production of hydrolysable tannin. According to the growth kinetics, a maximum biomass of 4.46±0.06g fresh cell weight and 1.33±0.04g dry cell weight were obtained from the optimal suspension medium consisted of MS medium+0.5mgL^-1 BAP+1.5mgL^-1 NAA. Chitosan was treated at the stationary phase which leads to the highest accumulation of hydrolysable tannin compared to the untreated control. Hydrolysable tannin was observed and compared using HPLC at the Rt of 4.91 in both chitosan treated and untreated cells. This is the first ever report where use of chitosan has been done to enhance the production of the hydrolysable tannin in P. debilis using cell suspension culture technique.

Elicitation of Jerusalem artichoke (Helianthus tuberosus L.) cell suspension culture for enhancement of inulin production and altered degree of polymerisation

BACKGROUND

Plant cell suspension cultures have emerged as a potential source of secondary metabolites for food additives and pharmaceuticals. In this study inulin accumulation and its degree of polymerisation (DP) in the treated cells in the same medium were investigated after treatment with six types of elicitors.

RESULTS

An in vitro cell suspension culture of Jerusalem artichoke (Helianthus tuberosus L.) was optimised by adding an extra nitrogen source. According to the growth kinetics, a maximum biomass of 5.48 g L^-1 was obtained from the optimal cell suspension medium consisted of Murashige and Skoog basic medium (MS) + 1.0 mg L^-1 α-naphthalene acetic acid (NAA) + 1.0 mg L^-1 6-benzylaminopurine (6-BA) + 0.5 mg L^-1 proline + 1.0 mg L^-1 glutamine. Methyl jasmonate (MeJA, 250 µmol L^-1 ) treatment for 15 days led to the highest levels of inulin (2955.27 ± 9.81 mg L^-1 compared to control of 1217.46 ± 0.26 mg L^-1 ). The elicited effect of five elicitors to the suspension cells of Jerusalem artichoke is as follows: AgNO₃ (Ag, 10 µmol L^-1 ), salicylic acid (SA, 75 µmol L^-1 ), chitosan (KJT, 40 mg L^-1 ), Trichoderma viride (Tv, 90 mg L^-1 ), yeast extract (YE, 0.25 mg L^-1 ), and the corresponding content of inulin is increased by 2.05-, 1.93-, 1.76-, 1.44- and 1.18-fold compared to control, respectively. The obvious effect on the percentage of lower DP in inulin was observed in cells treated with 40 mg L^-1 KJT, 0.25 mg L^-1 YE and 10 µmol L^-1 Ag.

CONCLUSIONS

Among the six types of elicitors, the descending order of inulin content is MeJA > Ag > SA > KJT > Tv > YE. For the purpose inulin with lower DP and its application to prebiotic food, three elicitors, including KJT, YE and Ag, can be used for the elicitation. © 2016 Society of Chemical Industry.

Phylogenetic spectrum and analysis of antibacterial activities of leaf extracts from plants of the genus Rhododendron

BACKGROUND

Plants are traditionally used for medicinal treatment of numerous human disorders including infectious diseases caused by microorganisms. Due to the increasing resistance of many pathogens to commonly used antimicrobial agents, there is an urgent need for novel antimicrobial compounds. Plants of the genus Rhododendron belong to the woody representatives of the family Ericaceae, which are typically used in a range of ethno-medical applications. There are more than one thousand Rhododendron species worldwide. The Rhododendron-Park Bremen grows plants representing approximately 600 of the known Rhododendron species, and thus enables research involving almost two thirds of all known Rhododendron species.

METHODS

Twenty-six bacterial species representing different taxonomic clades have been used to study the antimicrobial potential of Rhododendron leaf extracts. Agar diffusion assay were conducted using 80% methanol crude extracts derived from 120 Rhododendron species. Data were analyzed using principal component analysis and the plant-borne antibacterial activities grouped according the first and second principal components.

RESULTS

The leaf extracts of 17 Rhododendron species exhibited significant growth-inhibiting activities against Gram-positive bacteria. In contrast, only very few of the leaf extracts affected the growth of Gram-negative bacteria. All leaf extracts with antimicrobial bioactivity were extracted from representatives of the subgenus Rhododendron, with 15 from the sub-section Rhododendron and two belonging to the section Pogonanthum. The use of bacterial multidrug efflux pump mutants revealed remarkable differences in the susceptibility towards Rhododendron leaf extract treatment.

CONCLUSIONS

For the first time, our comprehensive study demonstrated that compounds with antimicrobial activities accumulate in the leaves of certain Rhododendron species, which mainly belong to a particular subgenus. The results suggested that common genetic traits are responsible for the production of bioactive secondary metabolite(s) which act primarily on Gram-positive organisms, and which may affect Gram-negative bacteria in dependence of the activity of multidrug efflux pumps in their cell envelope.

The durative use of suspension cells and callus for volatile oil by comparative with seeds and fruits in Capparis spinosa L

Capparis spinosa is one of the most important eremophytes among the medicinal plants, and continued destruction of these plants poses a major threat to species survival. The development of methods to extract compounds, especially those of medicinal value, without harvesting the whole plant is an issue of considerable socioeconomic importance. On the basis of an established system for culture of suspension cells and callus in vitro, Gas Chromatograph-Mass Spectrometer (GC-MS) was used for the volatile oil composition analyzing in seed, fruit, suspension cells and callus. Fatty acids were the major component, and the highest content of alkanes was detected in seed, with <1.0% in suspension cells and callus. Esters, olefins and heterocyclic compounds were significantly higher in fruit than in the other materials. The content of acid esters in the suspension cells and callus was significantly higher than in seed and fruit. This indicated that the suspension cells and callus could be helpful for increasing the value of volatile oil and replacing seeds and fruit partially as a source of some compounds of the volatile oil and may also produce some new medical compounds. The above results give valuable information for sustainable use of C. spinosa and provide a foundation for use of the C. spinosa suspension cells and callus as an ongoing medical resource.

Selective responses of enzymes in the two parallel pathways of rosmarinic acid biosynthetic pathway to elicitors in Salvia miltiorrhiza hairy root cultures

Rosmarinic acid and salvianolic acid B are two important phenolic compounds with therapeutic properties in Salvia miltiorrhiza Bunge. The biosynthesis of rosmarinic acid is initiated by two parallel pathways, namely the phenylpropanoid pathway and the tyrosine-derived pathway. Salvianolic acid B is a structural dimer of rosmarinic acid and is believed to be derived from rosmarinic acid. In the current study, methyl jasmonate (MeJA) and hyphal extracts from fungi were used as elicitors to examine the relationship between enzymes in the two parallel pathways and accumulation of phenolic compounds in S. miltiorrhiza hairy root cultures. The results showed that accumulations of rosmarinic acid, salvianolic acid B and total phenolics were enhanced by MeJA while suppressed by fugal extracts. Responses of enzymes in the tyrosine-derived pathway, at both the gene transcript and enzyme activity levels, showed a better consistency with alterations of phenolic compounds content after the two elicitors treated. Our study implied that compared with enzymes in the phenylpropanoid pathway, enzymes in the tyrosine-derived pathway are more correlated to rosmarinic acid and salvianolic acid B biosynthesis in S. miltiorrhiza hairy roots.

Influence of rare earth elements on metabolism and related enzyme activity and isozyme expression in Tetrastigma hemsleyanum cell suspension cultures

The effects of rare earth elements (REEs) not only on cell growth and flavonoid accumulation of Tetrastigma hemsleyanum suspension cells but also on the isoenzyme patterns and activities of related enzymes were studied in this paper. There were no significant differences in enhancement of flavonoid accumulation in T. hemsleyanum suspension cells among La(3+), Ce(3+), and Nd(3+). Whereas their inductive effects on cell proliferation varied greatly. The most significant effects were achieved with 100 μM Ce(3+)and Nd(3+). Under treatment over a 25-day culture period, the maximal biomass levels reached 1.92- and 1.74-fold and the total flavonoid contents are 1.45- and 1.49-fold, than that of control, respectively. Catalase, phenylalanine ammonia-lyase (PAL), and peroxidase (POD) activity was activated significantly when the REE concentration range from 0 to 300 μM, whereas no significant changes were found in superoxide dismutase activity. Differences of esterase isozymes under REE treatment only laid in expression level, and there were no specific bands. The expression level of some POD isozymes strengthened with increasing concentration of REEs within the range of 50-200 μM. When REE concentration was higher than 300 μM, the expression of some POD isozymes was inhibited; meanwhile, some other new POD isozymes were induced. Our results also showed REEs did not directly influence PAL activity. So, we speculated that 50-200 μM REEs could activate some of antioxidant enzymes, adjust some isozymes expression, trigger the defense responses of T. hemsleyanum suspension cells, and stimulate flavonoid accumulation by inducing PAL activity.

Optimization of the basal medium for improving production and secretion of taxanes from suspension cell culture of Taxus baccata L

Background and purpose of the study

Taxol is one of the most effective anticancer drugs that isolated from Taxus sp. due to the slow growth of Taxus trees and low concentration of Taxol in the tissues, the biotechnological approaches especially plant cell culture have been considered to produce Taxol in commercial scale.

Methods

We investigated the effects of basal medium type used in culture media on production of Taxol and other taxane compounds from cell suspension culture of T. baccata L. Briefly, five commonly basal media including Gamborg, Murashige and Skoog, Woody Plant, Schenk and Hildebrandt, and Driver and Kuniyuki medium were used for preparing separate suspension culture media. The intra- and extra-cellular yields of taxanes were analyzed by using HPLC after 21 days period of culturing.

Results

The yields of taxanes were significantly different for the cultures prepared by different basal media. Moreover, the effects of basal medium on the yield of products differed for varius taxane compounds. Maximum yields of Baccatin III (10.03 mgl^-1) and 10-deacetyl baccatin III (4.2 mgl^-1) were achieved from the DKW basal media, but the yield of Taxol was maximum (16.58 mgl^-1) in the WPM basal media. Furthermore, the secretion of taxanes from the cells into medium was also considerably affected by the type of basal medium. The maximum extra-cellular yield of Taxol (7.81 mgl^-1), Baccatin III (5.0 mgl^-1), and 10-deacetyl baccatin III (1.45 mgl^-1) were also obtained by using DKW basal medium that were significantly higher than those obtained from other culture media.

Mineral nutrient imbalance, DNA lesion and DNA-protein crosslink involved in growth retardation of Vicia faba L. seedlings exposed to lanthanum ions

Effects of mineral nutrient imbalance, DNA lesion and DNA-protein crosslink on growth of Vicia faba L. seedlings hydroponically cultivated in concentrations of extraneous lanthanum (La) for 20 days were investigated in the present experiment. The results showed that contents of La, Cu or K elements in roots generally changed synchronously with those in leaves, while Ca, Fe, Zn, Mg, Mn or P in the roots altered inversely to those in the leaves. Thus, the extraneous La led to redistribution and imbalance of mineral nutrient elements in the roots and leaves. DNA lesion and DNA-protein crosslink were investigated by single cell gel electrophoresis (SCGE) and sodium dodecyl sulfate/potassium (SDS/K+) precipitation methods, respectively. The results demonstrated that the increasing La induced DNA break and DNA-protein crosslinks (DPCs) in the seedlings. These results suggested that mineral nutrient imbalance, DNA lesion and DNA-protein crosslink were involved in the growth retardation and growth alteration of the seedlings, which may help to understand the mechanisms of rare earth elements (REEs) on plant growth.

Influence of abiotic stress signals on secondary metabolites in plants

Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and industrially important biochemicals. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Secondary metabolites play a major role in the adaptation of plants to the environment and in overcoming stress conditions. Environmental factors viz. temperature, humidity, light intensity, the supply of water, minerals, and CO2 influence the growth of a plant and secondary metabolite production. Drought, high salinity, and freezing temperatures are environmental conditions that cause adverse effects on the growth of plants and the productivity of crops. Plant cell culture technologies have been effective tools for both studying and producing plant secondary metabolites under in vitro conditions and for plant improvement. This brief review summarizes the influence of different abiotic factors include salt, drought, light, heavy metals, frost etc. on secondary metabolites in plants. The focus of the present review is the influence of abiotic factors on secondary metabolite production and some of important plant pharmaceuticals. Also, we describe the results of in vitro cultures and production of some important secondary metabolites obtained in our laboratory.

Lanthanum Element Induced Imbalance of Mineral Nutrients, HSP 70 Production and DNA-Protein Crosslink, Leading to Hormetic Response of Cell Cycle Progression in Root Tips of Vicia faba L. seedlings

The effects and mechanisms of rare earth elements on plant growth have not been extensively characterized. In the current study, Vicia faba L. seedlings were cultivated in lanthanum (La)-containing solutions for 10 days to investigate the possible effects and mechanisms of La on cell proliferation and root lengthening in roots. The results showed that increasing La levels resulted in abnormal calcium (Ca), Ferrum (Fe) or Potassium (K) contents in the roots. Flow cytometry analysis revealed G1/S and S/G2 arrests in response to La treatments in the root tips. Heat shock protein 70 (HSP 70) production showed a U-shaped dose response to increasing La levels. Consistent with its role in cell cycle regulation, HSP 70 fluctuated in parallel with the S-phase ratios and proliferation index. Furthermore, DNA-protein crosslinks (DPCs) enhanced at higher La concentrations, perhaps involved in blocking cell progression. Taken together, these data provide important insights into the hormetic effects and mechanisms of REE(s) on plant cell proliferation and growth.

Characterization and expression profile analysis of a new cDNA encoding taxadiene synthase from Taxus media

A full-length cDNA encoding taxadiene synthase (designated as TmTXS), which catalyzes the first committed step in the Taxol biosynthetic pathway, was isolated from young leaves of Taxus media by rapid amplification of cDNA ends (RACE). The full-length cDNA of TmTXS had a 2586 bp open reading frame (ORF) encoding a protein of 862 amino acid residues. The deduced protein had isoelectric point (pI) of 5.32 and a calculated molecular weight of about 98 kDa, similar to previously cloned diterpene cyclases from other Taxus species such as T. brevifolia and T. chinenisis. Sequence comparison analysis showed that TmTXS had high similarity with other members of terpene synthase family of plant origin. Tissue expression pattern analysis revealed that TmTXS expressed strongly in leaves, weak in stems and no expression could be detected in fruits. This is the first report on the mRNA expression profile of genes encoding key enzymes involved in Taxol biosynthetic pathway in different tissues of Taxus plants. Phylogenetic tree analysis showed that TmTXS had closest relationship with taxadiene synthase from T. baccata followed by those from T. chinenisis and T. brevifolia. Expression profiles revealed by RT-PCR under different chemical elicitor treatments such as methyl jasmonate (MJ), silver nitrate (SN) and ammonium ceric sulphate (ACS) were also compared for the first time, and the results revealed that expression of TmTXS was all induced by the tested three treatments and the induction effect by MJ was the strongest, implying that TmTXS was high elicitor responsive.

Paclitaxel: a review of adverse toxicities and novel delivery strategies

Better known as Taxol (Bristol-Myers Squibb), paclitaxel is the first member of the taxane family to be used in cancer chemotherapy. The taxanes exert their cytotoxic effect by arresting mitosis through microtubule stabilization, resulting in cellular apoptosis. The use of paclitaxel as a chemotherapeutic agent has become a broadly accepted option in the treatment of patients with ovarian, breast and non-small cell lung cancers, malignant brain tumors, and a variety of other solid tumors. However, significant toxicities, such as myelosuppression and peripheral neuropathy, limit the effectiveness of paclitaxel-based treatment regimens. This review addresses the toxicities associated with paclitaxel treatment and describes existing and future strategies of paclitaxel administration directed at limiting these toxicities.

Involvement of nitric oxide in cerebroside-induced defense responses and taxol production in Taxus yunnanensis suspension cells

This work was to characterize the generation of nitric oxide (NO) in Taxus yunnanensis cells induced by a fungal-derived cerebroside and the signal role of NO in the elicitation of plant defense responses and taxol production. (2S,2'R,3R,3'E,4E,8E)-1-O-beta-D-glucopyranosyl-2-N-(2'-hydroxy-3'-octadecenoyl)-3-hydroxy-9-methyl-4,8-sphingadienine at 10 microg/ml induced a rapid and dose-dependent NO production in the Taxus cell culture, reaching a maximum within 5 h of the treatment. The NO donor sodium nitroprusside (SNP) potentiated cerebroside-induced H(2)O(2) production and cell death. Inhibition of nitric oxide synthase activity by phenylene-1,3-bis(ethane-2-isothiourea) dihydrobromide or scavenging NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide partially blocked the cerebroside-induced H(2)O(2) production and cell death. Moreover, NO enhanced cerebroside-induced activation of phenylalanine ammonium-lyase and accumulation of taxol in cell cultures. These results are suggestive of a role for NO as a new signal component for activating the cerebroside-induced defense responses and secondary metabolism activities of plant cells.

Involvement of nitric oxide in oxidative burst, phenylalanine ammonia-lyase activation and Taxol production induced by low-energy ultrasound in Taxus yunnanensis cell suspension cultures

This work was to characterize the generation of nitric oxide (NO) in Taxus yunnanensis cells exposed to low-energy ultrasound (US) and the signal role of NO in elicitation of plant defense responses and secondary metabolite accumulation. The US sonication (3.5-55.6 mW/cm(3) at 40 kHz fixed frequency) for 2 min induced a rapid and dose-dependent NO production in the Taxus cell culture, which exhibited a biphasic time course, reaching the first plateau within 1.5 h and the second within 7 h after US sonication. The NO donor sodium nitroprusside (SNP) potentiated US-induced H(2)O(2) production and cell death. Inhibition of nitric oxide synthase (NOS) activity by N(omega)-nitro-L-arginine (L-NNA) or scavenging NO by 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxyde (PTIO) partially blocked the US-induced H(2)O(2) production and cell death. Moreover, the NO inhibitors suppressed US-induced activation of phenylalanine ammonium-lyase (PAL) and accumulation of diterpenoid taxanes (Taxol and baccatin III). These results suggest that NO plays a signal role in the US-induced responses and secondary metabolism activities in the Taxus cells.

Development and application of medicinal plant tissue cultures for production of drugs and herbal medicinals in China

In the search for new drugs and natural remedies, medicinal plants or herbs used in folk and traditional medicines are promising candidates. For the naturally rare and slowly growing plant species, plant tissue culture in bioreactors provides a cost-effective, sustainable and well-controlled means for mass production of the active principles of medicinal plants, and enables fuller utilization of their biosynthetic capacity. Recognizing that natural resources and agricultural land in China are limited,many Chinese research groups have engaged in the development of plant tissue culture techniques and processes for the cultivation and rapid propagation of medicinal plants, and for the biosynthesis and biotransformation of phytomedicines. This review primarily aims to provide a comprehensive summary of the major achievements in this and related research areas in China over the last three decades, but also to identify the difficulties and predict future trends in developing plant tissue culture biotechnology for the manufacture of bioactive natural products.

Plant cell culture for production of paclitaxel and other taxanes

Great advances in cell cultures of Taxus spp. for production of Taxol (generic name: paclitaxel) and other taxanes (taxoids) have been achieved in the past decade. This article reviews the manipulation of inducing factors--elicitors, gas composition, osmotic pressure, and conditioned medium; bioprocessing strategies--combining of inducing techniques, two-phase and two-stage cultivation, semi-continuous and perfusion cultures, and feeding of precursors or sugars; and bioreactors and scale-up. Perspectives on a more rational and efficient process involving metabolic engineering are also discussed.

Effects of rare earth elements on the growth of Cistanche deserticola cells and the production of phenylethanoid glycosides

The rare earth elements Nd, La, Ce at proper concentrations had positive effects on the cell growth of Cistanche deserticola and production of phenylethanoid glycosides (PeG). A mixture of rare earth elements (MRE, La(2)O(3):CeO(2):Pr(6)O(11):Sm(2)O(3)=255:175:3:1, mol/mol) showed the most remarkable effects. After 30 day's culture, 0.02 mmoll(-1) MRE gave the highest content (20.8%) and production (1.6 gl(-1)) of PeG, which were 104 and 167% higher than those obtained in control (without rare earth elements).