Cavitation fatigue in conifers: a study on eight European species

After drought-induced embolism and repair, tree xylem may be weakened against future drought events (cavitation fatigue). As there are few data on cavitation fatigue in conifers available, we quantified vulnerability curves (VCs) after embolism/repair cycles on eight European conifer species. We induced 50% and 100% loss of conductivity (LC) with a cavitron, and analyzed VCs. Embolism repair was obtained by vacuum infiltration. All species demonstrated complete embolism repair and a lack of any cavitation fatigue after 50% LC . After 100% LC, European larch (Larix decidua), stone pine (Pinus cembra), Norway spruce (Picea abies), and silver fir (Abies alba) remained unaffected, while mountain pine (Pinus mugo), yew (Taxus baccata), and common juniper (Juniperus communis) exhibited 0.4-0.9 MPa higher vulnerability to embolism. A small cavitation fatigue observed in Scots pine (Pinus sylvestris) was probably biased by incomplete embolism repair, as indicated by a correlation of vulnerability shifts and conductivity restoration. Our data demonstrate that cavitation fatigue in conifers is species-specific and depends on the intensity of preceding LC. The lack of fatigue effects after moderate LC, and relevant effects in only three species after high LC, indicate that conifers are relatively resistant against cavitation fatigue. This is remarkable considering the complex and delicate conifer pit architecture and may be important considering climate change projections.

Bioprospecting plant growth promoting endophytic bacteria isolated from Himalayan yew (Taxus wallichiana Zucc.)

The present study aims to investigate the endophytic bacteria, isolated from the roots of Taxus wallichiana Zucc. and designated as GBPI_TWL and GBPI_TWr, for their plant growth promoting traits. On the basis of phenotypic and molecular characters, the bacteria are identified as species of Burkholderia and Enterobacter, respectively. Both the bacteria could grow at wide range of temperature (5-40 °C, opt=25 °C) and pH (1.5-11.0, opt = 6-7), and tolerate salt concentration up to 12 %. While both the bacterial endophytes possessed siderophore, HCN, ammonia, and salicyclic acid producing abilities, GBPI_TWL showed IAA and ACC deaminase producing abilities, in addition. The bacteria were found to be potential phosphate solubilizers at wide temperature range (5-35 °C) by utilizing tricalcium, iron, and aluminium phosphate as substrate. Further, the bacterial isolates produced phytase and phosphatase enzymes in both acidic and alkaline conditions. Positive influence of the inoculation with the bioformulations of GBPI_TWL and GBPI_TWr was demonstrated on the test crops namely rice (Oryza sativa) and soybean (Glycine max) with respect to physico-chemical and plant growth parameters in net house experiments. The study will have implications in developing bioformulations, specifically for low temperature environments, in view of environmental sustainability.

Elevated O3 alters soil bacterial and fungal communities and the dynamics of carbon and nitrogen

Although many studies have reported the negative effects of elevated O₃ on plant physiological characteristics, the influence of elevated O₃ on below-ground processes and soil microbial functioning is less studied. In this study, we examined the effects of elevated O₃ on soil properties, soil microbial biomass, as well as microbial community composition using high-throughput sequencing. Throughout one growing season, one-year old seedlings of two important endemic trees in subtropical China: Taxus chinensis (Pilger) Rehd. var. chinensis, and Machilus ichangensis Rehd. Et Wils, were exposed to charcoal-filtered air (CF as control), 100 nl l^-1 (E100) or 150 nl l^-1 (E150) O₃-enriched air, in open top chambers (OTCs). We found that only higher O₃ exposure (E150) significantly decreased soil microbial biomass carbon and nitrogen in M. ichangensis, and the contents of organic matter were significantly decreased by E150 in both tree species. Although both levels of O₃ exposure decreased NO₃-N in T. chinensis, only E150 increased NO₃-N in M. ichangensis, and there were no effects of O₃ on NH₄-N. Moreover, elevated O₃ elicited changes in soil microbial community structure and decreased fungal diversity in both M. ichangensis and T. chinensis. However, even though O₃ exposure reduced bacterial diversity in M. ichangensis, no effect of O₃ exposure on bacterial diversity was detected in soil grown with T. chinensis. Our results showed that elevated O₃ altered the abundance of bacteria and fungi in general, and in particular reduced nitrifiers and increased the relative abundance of some fungal taxa capable of denitrification, which may stimulate N₂O emissions. Overall, our findings indicate that elevated O₃ not only impacts the soil microbial community structure, but may also exert an influence on the functioning of microbial communities.

The effects of salicylic acid and glucose on biochemical traits and taxane production in a Taxus baccata callus culture

The combined use of elicitors can be an effective way to increase the production of secondary metabolites (SMs) in plant cell, tissue and organ cultures. This study investigated the effects of a salicylic acid (SA) pretreatment and different glucose levels on the growth, biochemical traits and taxane production in a Taxus baccata callus culture. For this purpose, after a pretreatment with SA (5 μM), three-month-old calli were cultured on B5 medium fortified with different concentrations of glucose (0, 0.5, 1, 2 and 3%), and they were compared with calli cultured on a B5 medium supplemented only with glucose. When the calli were harvested at 21 days, their fresh weight (g), dry weight (g) and cell viability (%) had decreased significantly (p < 0.05) with the higher glucose concentrations. The glucose treatment increased the hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) content, and caused oxidative stress in treated tissues. The lower H₂O₂ content and oxidative stress was associated with an increased antioxidant enzyme activity in the SA-pretreated samples, which resulted in less membrane damage and improved growth and cell viability under the glucose treatment compared to the control. By reducing the activity of phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO), the SA pretreatment reduced the production and oxidation of phenolic compounds under the glucose treatment; this decrease was associated with less browning of tissues and higher viability. Increases in taxol (5.1-fold) and total taxanes (3.5-fold) in the SA-pretreated calli cultured on the medium containing 2% glucose, compared to the control, indicated that the two treatments had a significant effect on taxane production in the T. baccata callus culture.

Methyl jasmonate represses growth and affects cell cycle progression in cultured Taxus cells

Methyl jasmonate elicitation of Taxus cultures enhances paclitaxel accumulation, but represses growth by inhibition of cell cycle progression. Growth repression is evident both at the culture level and transcriptional level. Methyl jasmonate (MeJA) elicitation is an effective strategy to induce and enhance synthesis of the anticancer agent paclitaxel (Taxol(®)) in Taxus cell suspension cultures; however, concurrent decreases in growth are often observed, which is problematic for large-scale bioprocessing. Here, increased accumulation of paclitaxel in Taxus cuspidata suspension cultures with MeJA elicitation was accompanied by a concomitant decrease in cell growth, evident within the first 3 days post-elicitation. Both MeJA-elicited and mock-elicited cultures exhibited similar viability with no apoptosis up to day 16 and day 24 of the cell culture period, respectively, suggesting that growth repression is not attributable to cell death. Flow cytometric analyses demonstrated that MeJA perturbed cell cycle progression of asynchronously dividing Taxus cells. MeJA slowed down cell cycle progression, impaired the G1/S transition as observed by an increase in G0/G1 phase cells, and decreased the number of actively dividing cells. Through a combination of deep sequencing and gene expression analyses, the expression status of Taxus cell cycle-associated genes correlated with observations at the culture level. Results from this study provide valuable insight into the mechanisms governing MeJA perception and subsequent events leading to repression of Taxus cell growth.

Variation of Taxane Content in Needles of Taxus x media Cultivars with Different Growth Characteristics

Needles from 17 different Taxus x media cultivars, belonging to 4 groups showing different growth characteristics, were analyzed using high performance liquid chromatography for their content of 10-deacetylbaccatin III, baccatin III, cephalomannine and paclitaxel (Taxol®). The 4 Taxus x media cultivar groups were: 1.) medium to fast growing and upright form; 2.) slow growing and upright form; 3.) fast growing and spreading form; and 4.) slow growing and spreading form. The purpose of this study was to identify yew cultivars of fast growth rate, upright growth and high taxane content in their needles. The highest content of paclitaxel was found in ‘Coleana’ of group 1 (378 μg/g of the extracted dry weight). Three cultivars in group 1, ‘Coleana’, ‘Stovekenii’ and ‘Hicksii’, make good candidates for taxane extraction because of their high paclitaxel and 10-deacetylbaccatin III content, fast biomass accumulation and upright growing form. They are also good starting materials to develop alternative methods for the production of paclitaxel and its analogous compounds through modern biotechnology approaches.

[Supercritical CO2 fluid extraction and component analysis of leaves oil from Taxus chinensis var. mairei]

OBJECTIVE

To research the optimal extraction process of supercritical CO2 extraction and analyze the component of the oil extracted from leaves of Taxus chinensis var. mairei.

METHODS

Using the yield of leaves oil from Taxus chinensis var. mairei as the index, investigated the effect of the extraction pressure, extraction temperature and extraction time on the extracting-rate of leaves oil. The chemical composition of the extracted leaves oil was analyzed by derivatized GC-MS.

RESULTS

The optimal parameters of the supercritical CO2 extraction of the oil extracted from leaves of Taxus chinensis var. mairei were determined: CO2 compressor pump frequency was 10 Hz, the extraction pressure was 25 MPa and the temperature of extraction was 45 degrees C, the extraction time was 120 min, the isolator I pressure was 8.0 MPa and the temperature of extraction was 40 degrees C, the isolator II pressure was 5.0 MPa and the temperature of extraction was 35 degrees C. The extracted leaves oil was derivatized with boron trifluoride-methanol complex. Thirty-three kinds of fatty acids were identified by GC-MS.

CONCLUSION

The yield of leaves oils are different from Taxus chinensis var. mairei from 3 habitats. The yield of leaves oil from Donggang, Wuxi city is the highest, about 2.61%. The kinds of fatty acids with high amounts in leaves oil from Taxus chinensis var. mairei is identical in general, the kinds of fatty acids with low amounts in leaves oil from Taxus chinensis var. mairei have differences.

[Study on HPLC fingerprint of Taxus chinensis var. mairei]

OBJECTIVE

To establish the HPLC fingerprint of Taxus chinensis var. mairei collected from different parts during different seasons and provide scientific basis for its comprehensive utilization.

METHODS

Supercritical CO2 extraction was used to extract the effective fraction, HPLC method to establish the fingerprint and similarity evaluation software to analyze the fingerprint chromatogram.

RESULTS

12 batches of Taxus chinensis var. mairei medicinal materials from different parts collected in different seasons were analyzed and HPLC fingerprint of Taxus chinensis var. mairei was established.

CONCLUSION

The HPLC fingerprint can be used to evaluate the quality of Taxus chinensis var. mairei medicinal materials.

Loss of nuclear flavanols during drought periods in Taxus baccata

Normally, needles of Taxus baccata during the growth period prominently stain blue for nuclear flavanols with the histochemical DMACA procedure. However, under excess heat and drought conditions, nuclear flavanols of current-year needles decline to zero. Nevertheless, greenish-yellow-coloured flavonols (quercetin derivatives) were still observed in nuclei. All of these yellow nuclei were in a silenced state and without mitosis. This link between drought and loss of nuclear flavanols was found in 3 years, 2003, 2007 and 2010. In 2007, exceptional drought occurred in early spring, interrupted by short rains. This, in turn, led to flushing of new sprouts, a characteristic feature in which nuclei were overloaded with flavanols. By the end of three drought periods, all nuclei developed blue-coloured nuclear flavanols. The flavanols seem to be associated with the histone proteins of chromatin. The oxidative degradation of catechin in Tris buffer (pH 8.0) containing MgCl2 was studied in the presence of the H4-core fragment TYTEHAKRKTVTAMD, modified according to the epigenetic histone code. The results show that catechin degradation can be significantly inhibited by the non-modified peptides and the methylated peptides (methylation at both lysine residues). The acetylated and formylated peptides do not show this behaviour. These observations indicate that flavanol association at chromosomes appears to be regulated by the epigenetic histone code.

Bark removal and population structure of Taxus wallichiana Zucc. in a temperate mixed conifer forest of western Himalaya

Taxus wallichiana Zucc. (Himalayan yew) represents one of the most threatened medicinal tree species of the Himalayan region. Heavy exploitation of its bark and leaves for taxol® has resulted in decline in its population. Generating quantitative information on Himalayan yew has therefore been stressed. The present paper provides information on the population and bark removal of Himalayan yew from one of the interior areas of Himalaya. Total count and quadrat method were deployed to generate quantitative information on its population while bark removal was estimated based on depth and extent of bark removed. After analyzing the existing information and the results of the study, a rapid vulnerability assessment (RVA) of the species was carried out. Taxus reported a density of 72 individuals/ha and was present as an under canopy of Picea smithiana. Complete stripping of bark was observed in 11 % of the Taxus population which amounted to ca. 18,152.86 cm(3) of bark removed. The age class distribution showed complete absence of seedlings and saplings. RVA scores also reported higher values (26) thereby pointing toward the high vulnerability of this species. Across its entire distributional range, Taxus population is under severe pressure. It is high time when few patches of Taxus are demarcated as Medicinal Plant Conservation Areas, and detailed studies on its autecology are initiated.

[Content and distribution of active components in cultivated and wild Taxus chinensis var. mairei plants]

Taxus chinensis var. mairei is an endemic and endangered plant species in China. The resources of T. chinensis var. mairei have been excessively exploited due to its anti-cancer potential, accordingly, the extant T. chinensis var. mairei population is decreasing. In this paper, ultrasonic extraction and HPLC were adopted to determine the contents of active components paclitaxel, 7-xylosyltaxol and cephalomannine in cultivated and wild T. chinensis var. mairei plants, with the content distribution of these components in different parts of the plants having grown for different years and at different slope aspects investigated. There existed obvious differences in the contents of these active components between cultivated and wild T. chinensis var. mairei plants. The paclitaxel content in the wild plants was about 0.78 times more than that in the cultivated plants, whereas the 7-xylosyltaxol and cephalomannine contents were slishtly higher in the cultivated plants. The differences in the three active components contents between different parts and tree canopies of the plants were notable, being higher in barks and upper tree canopies. Four-year old plants had comparatively higher contents of paclitaxel, 7-xylosyltaxol and cephalomannine (0.08, 0.91 and 0.32 mg x g(-1), respectively), and the plants growing at sunny slope had higher contents of the three active components, with significant differences in the paclitaxel and 7-xylosyltaxol contents and unapparent difference in the cephalomannine content of the plants at shady slope. It was suggested that the accumulation of the three active components in T. chinensis var. mairei plants were closely related to the sunshine conditions. To appropriately increase the sunshine during the artificial cultivation of T. chinensis var. mairei would be beneficial to the accumulation of the three active components in T. chinensis var. mairei plants.

[Screening, identification, and promoting effect of phosphate-solubilizing bacteria in rhizosphere of Taxus chinensis var. mairei]

OBJECTIVE

Phosphate-solubilizing bacteria (PSB) were isolated, screened and identified from the rhizosphere of Taxus chinensis var. mairei, and growth-promoting effects on T. chinensis var. mairei by high effective PSB were determined.

METHODS

By using selective culture media, PSB were isolated from rhizospheric soil, the high effective PSB was further screened using NBRI-BPB medium, and the molybdenum-antimony anti-spectrophotometric method was applied to determine the phosphate-dissolving ability of the high effective PSB after four days fermentation in NBRIP medium. Bacteria were identified by the Biolog system combined with 16S rDNA gene sequence analysis and morphological, physiological and biochemical characteristics. The inoculation test in potted seedlings was carried out under the greenhouse.

CONCLUSION

Four strains of high effective PSB were screened and identified as Pseudomonas fluorescens, Bacillus cereus, Sinorhizobium meliloti and Bacillus licheniformis, respectively. These strains had significant effects on improving the growth of the seedlings of T. chinensis var. mairei.

Taxol content comparison in different parts of Taxus madia and Taxus chinensis var. mairei by HPLC

OBJECTIVE

To analysis and compare the taxol content in different parts of Taxus madia and Taxus chinensis var. mairei by High Performance Liquid Chromatography (HPLC).

METHODS

85% EtOH and CH2Cl2 were used for the extraction of taxol. By HPLC, the methodology study and taxol content investigation were performed.

RESULTS

The taxol was extracted successfully. One simple and reliable methodology was built up. Basing on these, the taxol content in these two Taxus spp. were analysed and compared, among of which the leaf of Taxus chinensis var. mairei has the highest taxol content (5.18 x 10(-5), w/w).

CONCLUSION

Taxol and its content in the original plants can be simply and reliably extracted and investigated by these methods, which also can provided the scientific basis for the rational development of Taxus spp.

[Point pattern analysis of different age-class Taxus chinensis var. mairei individuals in mountainous area of southern Anhui Province]

By using O-ring statistics in point pattern analysis and Programita software, this paper studied the spatial distribution patterns and associations of different age-class individuals of Taxus chinensis var. mairei populations at Xianyu and Xiaxiang in the mountainous area of southern Anhui Province. The Xianyu population had a random spatial distribution at the scales from 2 m to 25 m but a clumped distribution at the scales < 2 m, while the Xiaxiang population distributed randomly at all the scales. As for Xianyu population, its individuals of age-class I had a clumped distribution at the scales < 5 m, while the individuals of elder age-classes tended to be non-randomly distributed at more scales than < 5 m, which might be related to the features of population regeneration. With increasingly enlarged age-class differences, the spatial association between younger and elder age-classes individuals turned to be negative, but less spatial association was observed between adjacent age-classes individuals. Such a spatial relationship between different age-classes individuals of T. chinensis was beneficial to the effective use of resources. With the growth of the individuals, T. chinensis population had a transition from clumped to random distribution.

Enhancement of taxane production in hairy root culture of Taxus x media var. Hicksii

This study assessed the effect of two precursors (l-phenylalanine and p-amino benzoic acid) used alone or in combination with methyl jasmonate, on the growth and accumulation of paclitaxel, baccatin III and 10-deacetylbaccatin III in hairy root cultures of Taxus x media var. Hicksii. The greatest increase in dry biomass was observed after 4 weeks of culturing hairy roots in medium supplemented with 1microM of l-phenylalanine (6.2gL(-1)). Addition of 1microM of l-phenylalanine to the medium also resulted in the greatest 10-deacetylbaccatin III accumulation (422.7microg L(-1)), which was not detected in the untreated control culture. Supplementation with 100microM of l-phenylalanine together with 100microM of methyl jasmonate resulted in the enhancement of paclitaxel production from 40.3microg L(-1) (control untreated culture) to 568.2microg L(-1), the highest paclitaxel content detected in the study. The effect of p-amino benzoic acid on taxane production was less pronounced, and the highest yield of paclitaxel (221.8microg L(-1)) was observed when the medium was supplemented with 100microM of the precursor in combination with methyl jasmonate. Baccatin III was not detected under the conditions used in this experiment and the investigated taxanes were not excreted into the medium.

[Structrue identification of biflavones and determination of Taxol from Taxus Madia]

OBJECTIVE

To study the flavonoids from Taxus Madia and determine the content of Taxol from different parts of Taxus Madia.

METHODS

Various column chromatographic techniques were applied for isolation and purification. The structrues were elucidated by physico-chemical property and spectral evidence. The analysis of Taxol was carried out on C18 (150 mm x 4.6 mm i. d. 5 microm). The mobile phase was MeOH-H2O (3:1). The flow-rate was 0.8 ml/min. The detection wave-length was 228 nm.

RESULTS

Three bifiavonyl compounds were isolated and identified as Sciadopitysin (Compound I), Ginkgetin (Compound II), 7,7",4'-Tri-O-Methylamentoflavone (Compound III). The contents of Taxol from branches and leaves, main root, fibrous root was 0.0308 mg/g, 0.02191 mg/g, 0.01983 mg/g respectively.

CONCLUSION

Compound I-III are obtained from Taxus Madia for the first time. The contents of Taxol is the highest in the part of branches and leaves, and then is the main root, the lowest is the fibrous root.

[Quantitative changes of anti-cancer active components in Taxus chinensis var. mairei branches and leaves]

The quantitative changes of anti-cancer ingredients such as taxol, cephalomannine, baccatin III and 10-deacetylbaccatin III in the branches and leaves of Taxus chinensis var. mairei during one growth season were measured by HPLC. The results showed that the contents of these anticancer ingredients had an obvious change from April when the new branches began to germinate to November when the branches basically stopped growing. The contents of taxol and cephalomannine in the branches and leaves of T. chinensis had the same change pattern, with the peaks appeared in May, and those of Baccatin III and 10-deacetylbaccatin III had the same change trend, with the highest values appeared in September and April, respectively. There was a significant positive correlation between the contents of taxol and cephalomannine (P <0.05), and a negative correlation between the contents of cephalomannine and 10-deacetylbaccatin III (P <0.05).

Characterization of the expression patterns of LEAFY/FLORICAULA and NEEDLY orthologs in female and male cones of the conifer genera Picea, Podocarpus, and Taxus: implications for current evo-devo hypotheses for gymnosperms

The identity of genes causally implicated in the development and evolutionary origin of reproductive characters in gymnosperms is largely unknown. Working within the framework of plant evolutionary developmental biology, here we have cloned, sequenced, performed phylogenetic analyses upon and tested the expression patterns of LEAFY/FLORICAULA and NEEDLY orthologs in reproductive structures from selected species of the conifer genera Picea, Podocarpus, and Taxus. Contrary to expectations based on previous assessments, expression of LFY/FLO and NLY in cones of these taxa was found to occur simultaneously in a single reproductive axis, initially overlapping but later in mutually exclusive primordia and/or groups of developing cells in both female and male structures. These observations directly affect the status of the "mostly male theory" for the origin of the angiosperm flower. On the other hand, comparative spatiotemporal patterns of the expression of these genes suggest a complex genetic regulatory network of cone development, as well as a scheme of functional divergence for LFY/FLO with respect to NLY homologs in gymnosperms, both with clear heterochronic aspects. Results presented in this study contribute to the understanding of the molecular-genetic basis of morphological evolution in conifer cones, and may aid in establishing a foundation for gymnosperm-specific, testable evo-devo hypotheses.

Characterization and control of endophytic bacterial contaminants in in vitro cultures of Piper spp., Taxus baccata subsp. wallichiana, and Withania somnifera

Bacterial contamination is a serious problem that causes severe loss of in vitro grown cultures of a number of plants. This problem becomes even more acute if the bacterial contamination is of endophytic origin. In such cases, identification and characterization of the contaminants is essential for achieving specific control of the contaminants through selective use of antibiotic agents, especially if the routinely used contamination control methods practiced elsewhere in tissue culture studies are ineffective. Such is the case with the bacterial contamination observed in the present study. The five endophytic bacteria associated with Piper nigrum and Piper colubrinum, four endophytic bacteria associated with Taxus baccata subsp. wallichiana, two endophytic bacteria associated with Withania somnifera, and two bacteria common to all these plant species were isolated and characterized based on morphological and biochemical tests. Their taxonomic positions based on similarity indices were determined. A control strategy against these bacteria has been developed based on bacteriostatic or bactericidal actions of 12 antibiotics at three different concentrations by solid and liquid antibiogramme assays.

Micropropagation of endangered plant species

This chapter describes the multiple-shoot-based methods of micropropagation for endangered plant species. Taxus and aloe are used here as examples. For Taxus, the process of micropropagation includes initiating multiple shoots, elongating shoots, rooting shoots, and transplanting plantlets. For aloe, the process of micropropagation includes initiating multiple shoots, rooting shoots, and transplanting plantlets.

[Effects of aspect on distribution pattern of Taxus chinensis population in Yele, Sichuan Province: an analysis based on patches information]

Employing GIS method and based on patches information, this paper studied the effects of aspect on the distribution pattern of Taxus chinensis population in Yele, Sichuan Province. The results showed that Taxus chinensis population mainly distributed on the aspects of northwest, northeast, east and north. These aspect patches were absolutely dominant on area, mean size, mean edge and the number of Taxus chinensis. There existed a significant correlation between aspect and Taxus chinensis distribution. Taxus chinensis distributed preferentially on north, northeast, northwest and east patches, then on west and southwest patches, and finally on flat and southeast patches. The distribution patterns of Taxus chinensis in Yele were clustering, except on south aspect patches. The intensity of clustering on north aspect patches was the highest, with the value of Clark-Evans (CE) index being 0.906. The intensity of clustering on northeast and northwest aspect patches was lower than that on north aspect patches, with the CE value 0.797 and 0.563, respectively. The CE values on the rest aspect patches were all not larger than 0.5. There existed a significant positive correlation between the intensity of clustering index, number of patches, total patch edge, and the number of Tarus chinensis distributed on the patches, with the value of correlation coefficient 0. 936, 0.735 and 0.802, respectively. There were no significant correlations among the intensity of clustering, patch area, mean patch size, mean patch edge, and mean shape index of aspect patches.

Novel fluoro- and hydroxyl-containing jasmonate derivatives as highly efficient elicitors in suspension cultures of Taxus chinensis

To develop more effective abiotic elicitors for cell suspension cultures of T. chinensis to meet the needs for paclitaxel as anti-tumor drug, some fluoro- or hydroxyl-containing groups are introduced to the ester moiety of jasmonic acid by the esterification or acylation with bis(trichloromethyl) carbonate and corresponding alcohol. Some of them are found to be novel and effective elicitors, which can enhance the production of taxuyunnanine C (Tc) up to 60% more than that by methyl jasmonate (MJA) in T. chinensis cell cultures.

[Life table and spectral analysis of endangered plant Taxus chinensis var. mairei population]

Based on the investigation in Longxi Mountain National Nature Reserve and the theory of survival analysis, a static life table of Taxus chinensis var. mairei population was worked out, the curves of its survival rate, mortality rate and killing power were drawn, and the population dynamics was analyzed by spectral analysis. The results showed that the survival curve of the population appeared to be a type of Deevey-III, and the high mortality of seeding was one of the important reasons which caused Taxus chinensis var. mairei to be endangered. The spectral analysis of the population showed that there was a marked periodic regularity in the process of natural regeneration of Taxus chinensis var. mairei.

[Structure and dynamics of Taxus chinensis var. mairei clonal population]

Structure and dynamics of Taxus chinensis var. mairei clonal population were studied. The results showed that according to the life history of Taxus chinensis var. mairei, the modular population could be divided into 6 classes. The development of Taxus chinensis var. mairei population was greatly depended on its ramets, which sprouted on its stem, and the population size structure was stable. The survival curve of Taxus chinensis var. mairei population showed a revered 'J' type. To expanding and continuing the population, there were high ramet sprouting rate and the resource limit induced a higher seedling and sapling mortality rate. When sapling grew up as young tree, its adventitious root stretched into soil to assimilate the nutrient and water, and it became independence individual. Before germination, the seed of Taxus need to dormant for more than one year, and the bird and beast liked to eat the seed, so it was hard to find seedling and sapling from seed. Therefore Taxus chinesis var. mairei had been considered to be a decline or none descendant population. In this study, it was found that Taxus chinensis var. mairei had a powerful asexual multiplication in Yuanbaoshan, especially ramet sprouting on stem. It was depend on this way to develop and expand the population.

Paclitaxel production by plant-cell-culture technology

Plant cells catalyze multiple-step reactions of secondary metabolite biosynthesis, and selectively synthesize chiral compounds with polycyclic structures. Taking advantage of this characteristic, we studied the production of the anticancer drug paclitaxel, which is currently produced in limited supply. Callus culture investigations indicate that woody plant medium supplemented with 10(-5) mol L(-1) 1-naphthylacetic acid and without the NH4+ -type ion is the best condition for growth of the callus. The accumulation of paclitaxel and related taxanes in Taxus plants is thought to be a biological response to specific external stimuli. Several signal transducers were screened; taxane biosynthesis was strongly promoted by methyl jasmonate (MeJA) and silver thiosulfate (STS) as an anti-ethylene compound. Of ten taxane-type diterpenoids isolated from T. baccata suspension-cultured cells treated with MeJA, five have a phenylisoserine side-chain at the C-13 position of the taxane skeleton. Time-course analysis revealed two regulatory steps in taxane biosynthesis: the taxane-ring formation step and the acylation step of the C-13 position. Methyl jasmonate promoted the formation of the taxane-ring. The production of paclitaxel reached a maximum level of 295 mg L(-1) in a large-scale culture of T. x media cells using a two-stage process.

Novel synthetic jasmonates as highly efficient elicitors for taxoid production by suspension cultures ofTaxus chinensis

Suspension cultures of Taxus chinensis were used as a model plant cell system to evaluate novel synthetic jasmonates as elicitors for stimulating the biosynthesis of secondary metabolites. Significant increases in accumulation of taxuyunnanine C (Tc) were observed in the presence of newly synthesized 2-hydroxyethyl jasmonate (HEJA) and trifluoroethyl jasmonate (TFEJA) without their inhibition on cell growth. Addition of 100 microM HEJA or TFEJA on day 7 led to a high Tc content of 44.3 +/- 1.1mg/g or 39.7 +/- 1.1 mg/g (at day 21), while the Tc content was 14.0 +/- 0.1 mg/g and 32.4 +/- 1.6 mg/g for the control and that with addition of 100 microM methyl jasmonate (MJA), respectively. The superior stimulating ability of HEJA and TFEJA over MJA, which was generally considered as the best chemical for eliciting taxoid biosynthesis, suggests that the novel jasmonate analogues may have great potential in application to other cell culture systems for effcient elicitation of plant secondary metabolites.

Preparation of single cells from aggregatedTaxus suspension cultures for population analysis

A method for the isolation of single plant cells from Taxus suspension cultures has been developed for the analysis of single cells via rapid throughput techniques such as flow cytometry. Several cell wall specific enzymes, such as pectinase, pectolyase Y-23, macerozyme, Driselase(R), and cellulase were tested for efficacy in producing single cell suspensions. The method was optimized for single cell yield, viability, time, and representivity of aggregated cell cultures. The best combination for single cell isolation was found to be 0.5% (w/v) pectolyase Y-23 and 0.04% (w/v) cellulase. High viability (>95%) and high yields of single cell aggregates (>90%) were obtained following 4 hours of digestion for four separate Taxus cell lines. In addition, methyl jasmonate elicitation (200 microM) was found to have no effect on three of the four tested Taxus lines. Isolated single cells were statistically similar to untreated cell cultures for peroxidase activity (model cell wall protein) and paclitaxel content (secondary metabolite produced in Taxus cell cultures). In comparison, protoplasts showed marked changes in both peroxidase activity and paclitaxel content as compared to untreated cultures. The use of flow cytometry was demonstrated with isolated cells that were found to have > 99% viability upon staining with fluorescein diacetate. The development of a method for the isolation of single plant cells will allow the study of population dynamics and culture variability on a single cell level for the development of population models of plant cell cultures and secondary metabolism.

A structured kinetic model for suspension cultures of Taxus chinensis var. mairei induced by an oligosaccharide from Fusarium oxysporum

A structured kinetic model was established to describe the process of Taxol formation in suspension cultures of Taxus chinesis var. mairei induced by an oligosaccharide from Fusarium oxysporum. In this model, the role of intracellular starch as a storage carbon source had to be taken into account. Substrate uptake, culture growth, cell respiration, and secondary metabolites, predicted by the model, agreed with those obtained experimentally. The effective factors of oligosaccharide elicitation, eta(e,j), defined as the ratio of the parameter values in the system with oligosaccharide to those in control, reflected the effects of the oligosaccharide on cell growth and Taxol production.

Enhancement of taxol production and release in Taxus chinensis cell cultures by ultrasound, methyl jasmonate and in situ solvent extraction

This study evaluates the use of a novel mechanical stimulus, ultrasound (US), and a putative chemical elicitor, methyl jasmonate (MJ), combined with in situ solvent extraction (two-phase culture), to enhance taxol production by Taxus chinensis cells in suspension culture. The volumetric taxol yield was increased 1.5- to 1.8-fold with 2 min US treatment once or twice during a 4-week culture period, about 5-fold with 60-120 microM MJ, and 7- to 9-fold by in situ solvent extraction of taxol with dibutyl phthalate (DBP) (11% v/v). The percent of extracellular taxol or taxol release was also significantly increased. The combined use of US (day 5 or 9) and MJ treatment (day 7) resulted in taxol yields 20-50% higher than each of the treatments used alone. The most favorable strategy for taxol production was the application of US or MJ treatment, followed by in situ solvent extraction, giving rise to a taxol yield of 33-35 mg/l, about 17-fold higher than the control, at 1.9 mg/l. It was found that the organic solvent DBP, as well as US and MJ, stimulated the enzyme activity of secondary metabolic pathways, which was partially responsible for the enhanced taxol production.

[Industrialization of medicinal plant tissue culture]

Compared with other countries, the industrialization of medicinal plant tissue culture is more important for our country because China is consuming and exporting the most amounts of herb materials in the world. Each year, many papers and patents are published on cell cultures of popular medicinal plants, such as Taxus sp., Catharanthus roseus, and Panax ginseng, and, meanwhile, the research on organ cultures of medicinal plants is increasing very quickly, which is deepening the study of medicinal plant tissue culture. During the past 30 years, Chinese scientists have cultured many medicinal plant cells, organs and hairy roots. In addition, the large-scale cultures have been tested on medicinal plants, such as Catharanthus roseus, Panax notoginseng, Anisodus acutangulus, Lithospermum erythrorhizon, and Taxus chinensis. However, the bioreactor size is not big enough for the commercial cultivation and we have not mastered the culture technique on a large scale. We should clearly understand the importance and great potential benefit of medicinal plant tissue culture and develop the tissue culture techniques for the modernization of TCM. To develop the technique that we have the property right, the pioneering spirit is needed in our research, and, meanwhile, it should be pointed out emphatically the collaboration is indispensable among scientists from different research fields.

Inhibition of paclitaxel and baccatin III accumulation by mevinolin and fosmidomycin in suspension cultures of Taxus baccata

To achieve a better understanding of the metabolism and accumulation of paclitaxel and baccatin III in cell cultures of Taxus, inhibitors of the early steps in the terpenoid pathway were applied to a cell suspension culture of Taxus baccata: fosmidomycin as an inhibitor of the non-mevalonate branch of the pathway, and mevinolin as an inhibitor of the mevalonate branch. Synthesis of both taxanes in the cell suspension was first increased when cultured in the product formation medium supplemented with methyljasmonate (100 microM). The product formation medium was selected after assaying 24 different culture media. When fosmidomycin (200 microM) was added to the product formation medium together with the elicitor, the accumulation of paclitaxel and baccatin III was reduced by up to 3.0 and 1.5 times, respectively, whereas the inhibitory effect of mevinolin (1 microM) was only clearly exerted in the case of paclitaxel. Under the conditions of our experiment, we conclude that in the synthesis of both taxanes, the non-mevalonate pathway is the main source of the universal terpenoid precursor isopentenyl diphosphate (IPP).

Effects of inoculum size and age on biomass growth and paclitaxel production of elicitor-treated Taxus yunnanensis cell cultures

Suspension cultures of Taxus yunnanensis cells were inoculated with cells of different culture ages (12-24 days) at various densities [50-250 g fresh weight (fw)/l], and treated (on day 7) with a mixture of elicitors, including Ag(+), chitosan and methyl jasmonate. The biomass productivity (during the production stage) increased dramatically with inoculum size, but decreased with inoculum age over 16 days. The volumetric yield and productivity of taxol (paclitaxel) also increased with inoculum size, while the specific taxol yield (per cell) was mainly dependent on inoculum age, with an optimum of 20 days, during the early stationary phase. The highest taxol yield and productivity, 39.8 mg/l and 1.9 mg/l per day, respectively, were obtained with a 20-day-old inoculum at 200 g fw/l. Taxol excretion by the cells increased with inoculum age but decreased with inoculum size. The elicitor-induced activities of catalase (CAT) and phenylalanine ammonia-lyase (PAL) also depended mainly on inoculum age; higher PAL activity and lower CAT activity were obtained with an older inoculum, corresponding to a higher taxol yield. The results show that both inoculum size and age are important variables for taxol production, though the latter more profoundly influences elicitor-induced taxol biosynthesis of the cells. Inoculum size and age are also interrelated and should be optimized together in a two-stage culture process.

Abietane diterpenoids from callus cultures of Taxus baccata

A new compound was isolated from calli of Taxus baccata L. and assigned the structure 3beta,11-dihydroxy-12-methoxyabieta-8,11,13-triene-7-one. Two other metabolites were identified as 3-oxocryptojaponol and taxamairein C, both previously isolated from Taxus mairei.

[Differences in gene expression between Taxus chinensis cells during Taxol-synthesis phase and those during non-Taxol-synthesis phase]

In plant, evocation of secondary metabolism is associated with complex biochemical and molecular events that are regulated by developmental and environmental factors. In order to get more information about Taxol biosynthesis, comparison of mRNA populations from Taxus chinensis cells during Taxol-synthesis phase and those during non-Taxol-synthesis phase were performed by mRNA differential display. The results suggested that genes specifically expressed in the Taxol-synthesis phase might be involved in Taxol biosynthesis.

[Community types, phenology and propagation characteristics of Taxus mairei in north Guangdong]

Community types, phenology and propagation characteristics of Taxus mairei in north Guangdong were studied. The results showed that in north Guangdong province, Taxus mairei mainly distributed in the typical ever-green broad-leaf forest of lower and mid-subtropics dispersedly. Terminal bud of Taxus mairei was formed in late October and begun to grow foliages in mid-April, male flower bud was appeared in mid-May and the efflorescence was from late July to late November, female flower bud was formed in late August and the efflorescence was from late October to late January of second year, and the fruit mature period was in early October of second year. Under natural condition, the seed germination needed 2-3 years. Under experimental condition, the germination rate could be up to 82.2%. The effect of cuttage was better by taking mature annual twig and pretreatment by ABT1(100 mg.L-1) from October to November every year, and the rooting rate could be up to 95%.

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

The trivalent ion of a rare earth element, lanthanum, was tested for elicitor-like effects on taxol production in suspension cultures of four different Taxus spp cells. In T. yunnanensis cell cultures, the lanthanum ion at concentrations from 1.15 to 23.0 microM stimulated taxol production. The lanthanum ion also promoted taxol excretion by the T. yunnanensis cells considerably. The maximum stimulation of taxol production was achieved by the addition of 5.8 microM La3+ to the culture during mid-log growth phase, increasing the volumetric taxol yield by nearly threefold, from 2.61+/-0.37 to 9.89+/-1.92 mg l(-1) over a 28 day culture period. At higher concentrations, i.e. 23.1 and 46.2 microM, however, the lanthanum ion caused significant growth inhibition. For the other three Taxus cell lines, namely an embryo and a leave cell of T. chinensis and a stem cell of T. chinensis marv, the addition of lanthanum ion to the culture only had a significant effect on taxol production by the T. chinensis marv stem cells, increasing the volumetric yield by about threefold to 4.69+/-0.76 mg l(-1). These results suggest that lanthanum has elicitor-like effects on secondary metabolite synthesis of plant cell cultures.

[Effects of culture conditions on callus growth and taxol formation of Taxus yunnanensis Cheng et L.K.Fu]

OBJECTIVE

To seek culture conditions suitable for the callus growth and taxol formation of Taxus yunnanensis.

METHOD

Determining the growth index and taxol content in the callus cultured under different illumination conditions or on different media.

RESULTS AND CONCLUSION

Darkness, the combination of 0.1 mg.L-1BAP and 2,4-D 1.0 mg.L-1, and B5, DCR or 6,7-V basal medium were favorable for the callus growth and taxol formation of Taxus yunnanensis; high NO3- concentration in the medium promoted callus growth, and high NH4+ concentration greatly inhibited callus growth, but dramatically increased taxol content.

[Distribution pattern and its dynamics of Taxus chinensis var. mairei population on Yunbaoshan Mountain]

Field data were sampled by the method of contiguous grid quadrate, and t-test of v/m ratio, negative binomial parameter, Green's index, Cassie's index, dispersion index, clumping index, mean crowding index and patchiness index were used to analyse the distribution pattern and its dynamics of Taxus chinensis var. mairei population. The result shows that the distribution pattern was clustering. From sapling to grown-up tree, the clustering degree was decreasing, while the big trees had a random distribution.

[Habitats and present situations of 13 rare precious medicinal materials in Funiu mountains]

The living resources are very abound in the Funiu mountains area because of its special geographical position and climate, and there are also many rare precious living beings and Chinese medicinal herbs, for example, Taxus mairei, Ginkgo biloba, Gastrodia elata, Dendrobium huashanense, Physochlaina infunbularis, Cypripedium japonicum, Dysosma versipellis, Moschus moschiferus, Megalobatrachus davidanus, Succinum, etc, and conscious protection and rational development is an urgent task.