Identification of genes associated with biosynthesis of bioactive flavonoids and taxoids in Taxus cuspidata Sieb. et Zucc. plantlets exposed to UV-B radiation.

UV-B radiation is a typical environmental stressor that can promote phytochemical accumulation in plants. Taxus species are highly appreciated due to the existence of bioactive taxoids (especially paclitaxel) and flavonoids. However, the effect of UV-B radiation on taxoid and flavonoid biosynthesis in Taxus cuspidata Sieb. et Zucc. is largely unknown. In the present work, the accumulation of taxoids and flavonoids in T. cuspidata plantlets was significantly induced by 12 and 24 h of UV-B radiation (3 W/m2), and a large number of significantly differentially expressed genes were obtained via transcriptomic analysis. The significant up-regulation of antioxidant enzyme- and flavonoid biosynthesis-related genes (phenylalanine ammonia lyase 1, chalcone synthase 2, flavonol synthase 1, and flavonoid 3', 5'-hydroxylase 2), suggested that UV-B might cause the oxidative stress thus promoting flavonoid accumulation in T. cuspidata. Moreover, the expression of some genes related to jasmonate metabolism and taxoid biosynthesis (taxadiene synthase, baccatin III-3-amino 3-phenylpropanoyltransferase 1, taxadiene-5α-hydroxylase, and ethylene response factors 15) was significantly activated, which indicated that UV-B might initiate jasmonate signaling pathway that contributed to taxoid enhancement in T. cuspidata. Additionally, the identification of some up-regulated genes involved in lignin biosynthesis pathway indicated that the lignification process in T. cuspidata might be stimulated for defense against UV-B radiation. Overall, our findings provided a better understanding of some potential key genes associated with flavonoid and taxoid biosynthesis in T. cuspidata exposed to UV-B radiation.

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.

Comprehensive temporal reprogramming ensures dynamicity of transcriptomic profile for adaptive response in Taxus contorta.

Plants respond to the environmental perturbations by triggering the dynamic changes within the transcriptome. The assessment of these oscillations within the transcriptome would offer insights into the ecological adaptation of the plants. We evaluated how the transcriptome of Taxus contorta swings under natural conditions to elucidate its adaptive response. Thus, our study provides new insights into the performance of T. contorta under a changing environment during different seasons. The abundance estimation using the RNAseq approach revealed 6727 differentially expressed genes. Comprehensive reprogramming was observed in Taxol biosynthesis, maintenance of redox homeostasis, and generation of effective shield to UV-B, high light intensity, and temperature. Besides differential expression, the alternative splicing (AS) and single nucleotide variations (SNVs) also confer flexibility to the transcriptome of T. contorta. 1936 differentially expressing transcripts were also found to exhibit Differential Exon Usage (DEU) as well as differential SNVs. LC-MS-based untargeted metabolic analysis revealed 7774 ion features, among which around 334 putatively identified metabolites were differentially regulated. Our results showed that the swing and the oscillations of the transcriptome and metabolome of T. contorta ensure adaptability and better survival under changing environment. In addition, varying patterns of AS and SNVs compliment the adaptation provided by differential expression.

Response of rhizosphere bacterial community of Taxus chinensis var. mairei to temperature changes.

BACKGROUND: Temperature is a key factor influencing the growth and distribution of Taxus chinensis var. mairei, which is of high medicinal value. However, there is little information about the changes in rhizosphere bacterial community of Taxus chinensis var. maire under different temperatures. METHODS: In this study, the rhizosphere bacterial communities of Taxus chinensis var. maire under a series of temperatures [5°C (T5), 15°C (T15), 25°C (T25), 35°C (T35)] were assessed through high-throughput sequencing. And some taxa annotated as Mitochondria were positively correlated with the activity of SOD. RESULTS: Activity of peroxidase (POD) and superoxide dismutase (SOD) were increased and decreased respectively with increasing incubation temperature, showing that SOD may be the dominant reactive oxygen species (ROS) detoxifying enzyme in Taxus chinensis var. maire under low temperature. Taxus chinensis var. maire enriched specific bacterial taxa in rhizosphere under different temperature, and the rhizosphere bacterial diversity decreased with increasing temperature. CONCLUSION: The results indicated that rhizosphere bacteria may play important role for Taxus chinensis var. maire in coping with temperature changes, and the management of rhizosphere bacteria in a potential way to increase the cold resistance of Taxus chinensis var. mairei, thus improving its growth under low temperature and enlarging its habitats.

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.

[Not Available]. / Characteristic and protection of rare and endangered Taxus chinensis var. maireiin the Taihang Mountains.

The endangered causes of Taxus chinensis var. maireiin the Taihang Mountains are analyzed in three sides in connection with the situation that is resources increasing attenuation.The first is biological factors such as pollination barriers, deeply dormancy seed, cannot vegetative propagation under natural conditions, poor adaptability of seedling to environment and slow growth. The second is environmental factors such as very limited distribution environment and position in community. The third is interference of persons and other animals.According to these factors, we provide three measures to protect Taxus chinensis var. maireiin three sides that protect existing resources, breed subsequent resources and find new pathway of producing taxol.

Characteristic and protection of rare and endangered Taxus chinensis var. mairei in the Taihang Mountains / Características y protección de la especie en peligro de extinción Taxus chinensis var. mairei en las montañas de Taihang

The endangered causes of Taxus chinensis var. mairei in the Taihang Mountains are analyzed in three sides in connection with the situation that is resources increasing attenuation. The first is biological factors such as pollination barriers, deeply dormancy seed, cannot vegetative propagation under natural conditions, poor adaptability of seedling to environment and slow growth. The second is environmental factors such as very limited distribution environment and position in community. The third is interference of persons and other animals. According to these factors, we provide three measures to protect Taxus chinensis var. mairei in three sides that protect existing resources, breed subsequent resources and find new pathway of producing taxol (AU)

Las razones por las que la especie Taxus chinensis var. mairei está en peligro de extinción en las montañas de Taihang giran en torno a tres ejes distintos en relación a la disminución de ejemplares. En primer lugar contamos con factores biológicos, como las barreras de polinización, el alto grado de inactividad de sus semillas, la imposibilidad de propagación vegetal por medios naturales, la escasa adaptación de los vástagos al medio y su lento crecimiento. El segundo factor es de carácter ambiental: medio de distribución y posición en la comunidad muy limitados. Por último, la tercera causa es la interferencia de personas y animales. De acuerdo con estos factores, proponemos tres medidas para proteger la especie Taxus chinensis var. mairei con el fin de conservar los ejemplares existentes, cultivar nuevos ejemplares y encontrar nuevas vías para producir taxol (AU)

[Effects of forest gap size on the growth and form quality of Taxus wallichina var. mairei in Cunninghamia lanceolata forests]. / æž—çª—å¤§å°å¯¹æ‰æœ¨æž—å† å—æ–¹çº¢è±†æ‰ç”Ÿé•¿ä¸Žå½¢è´¨çš„å½±å“.

In order to clarify the effects of forest gap size on the growth and stem form quality of Taxus wallichina var. mairei and effectiveness of the precious timbers cultivation, 25 sample plots in Cunninghamia lanceolata forest gaps were established in Mingxi County, Fujian Province, China to determine the indices of the growth, stem form and branching indices of T. wallichina var. mairei seedlings. The relationships between the gap size and growth, stem form and branching were investigated. The 25 sample plots were located at five microhabitats which were classified based on gap size as follows: Class1, 2, 3, 4 and 5, which had a gap size of 25-50 m2, 50-75 m2, 75-100 m2, 100-125 m2 and 125-150 m2, respectively. The evaluation index system of precious timbers was built by using hierarchical analysis. The 5 classes of forest gaps were evaluated comprehensively by using the multiobjective decision making method. The results showed that gap size significantly affected 11 indices, i.e., height, DBH, crown width, forking rate, stem straightness, stem fullness, taperingness, diameter height ratio, height under living branch, interval between branches, and max-branch base diameter. Class1and 2 both significantly promoted the growth of height, DBH and crown width, and both significantly inhibited forking rate and taperingness, and improved stem straightness. Class2 significantly improved stem fullness and diameter height ratio. Class1and 2 significantly improved height under living branch and reduced max-branch base diameter. Class 1 significantly increased interval between branches. Class1and2 significantly improved the comprehensive evaluation score of precious timbers. This study suggested that controlled cutting intensity could be used to create forest gaps of 25-75 m2, which improved the precious timber cultivating process of T. wallichina var. mairei in C. lanceolata forests.

[Natural distribution and community ecological characteristics of Taxus chinensis var. mairei in Shanxi Province, China.] / 山西省南方红豆杉自然分布与群落生态学特征.

Taxus chinensis var. mairei is a national Category 1 protective species in China, with its northernmost natural distribution to the southeast of Shanxi Province, China. This study was conducted to investigate the natural distribution of T. chinensis var. mairei in Shanxi Province. The community classification, species diversity, population structure and competition intensity of T. chinensis var. mairei were studied. The results showed that T. chinensis var. mairei mainly formed four community types, including the community of T. chinensis var. mairei + Carpinus turczaninowii, the community of T. chinensis var. mairei - Vitex negundo var. heterophylla, the community T. chinensis var. mairei - Clerodendrum trichotomum and the community of T. chinensis var. mairei + Quercus variabilis. T. chinensis var. mairei was concentratedly distributed in Mohe of Linchuan County and Manghe Nature Reserve of Yangcheng County, and scattered in some other areas. The communities had an obviously vertical structure, with T. chinensis var. mairei trees growing into main canopy which were about 8-10 m high in mixed forests and 5-6 m high in pure forests. The species diversity index and evenness index had significant difference among the four community types. The average height of T. chinensis var. mairei was 5.16 m. The individuals in tree layer and succession layer were 43.4% and 56.6%, respectively, while they were scarce in the regeneration layer. 67.6% of the trees were small-diameter (DBH＜16 cm) and only 4.0% were large-diameter (32 cm≤DBH＜40 cm). T. chinensis var. mairei was considered to be lack of seedlings because only 4 seedlings were found, which might result in the declination of this species in future. T. chinensis var. mairei in Shanxi Province showed relatively concentrated distribution, with most individuals being small-diameter, resulting in tense intraspecific competition which accounted for 61.8% of the total intensity. The interspecific competition to T. chinensis var. mairei was mainly from C. turczaninowii and Q. variabilis, which were two dominant tree species with larger population in this area.

The query of suitable areas for plantation and development of Taxus baccata L species by using GIS in northern Iran.

Taxus baccata is a native species to the Caspian forests and is considered as the identification of these forests by some resources. The aim of this study was to understand the ecological characteristics of T. baccata in order to find suitable areas for its plantation in the Pone Aram preserve of Golestan province. Therefore, Multi-Criteria Evaluation (MCE) methods based on Analytical Hierarchy Process (AHP) were used. In this process at first the needed and effective natural indexes were used as 10 parameters. Then the final map of suitable areas for T. baccata plantation were produced based on Bolian and MCE models. According to the results, in Bolian method about 6218 ha of the total area of the study site (30554 ha) were estimated as suitable and semi suitable and 24336 ha were estimated as unsuitable for MCE model showed that about 2482 ha of the whole 30554 ha area of the study site is adequate for T. baccata plantation and 6181 ha is not adequate for T. baccata plantation. Regarding the results of the MCE and Bolian methods it has been concluded that for dynamic ecological parameters in delineation of suitable areas for T. baccata plantation the MCE weighting is more appropriate than Bolian. Using the results of this investigation it is possible to adequate areas for the presence of T. baccata and to execute a plan in order to facilitate the plantation of T. baccata in northern forests of Iran (watershed 88).

Optimization of the fractional precipitation of paclitaxel from a Taxus chinensis cell culture using response surface methodology and its isolation by consecutive high-speed countercurrent chromatography.

A consecutive preparation method for the isolation and purification of paclitaxel from the Taxus Chinensis cell culture was developed in this study. The process involved alkaline Al2O3 chromatography, fractional precipitation, and high-speed countercurrent chromatography. The original cell culture materials were first extracted with methanol using ultrasound-assisted extraction, and then the extract (the content of paclitaxel is 1.5%) was separated by alkaline Al2O3 column chromatography. Subsequently, fractional precipitation was used to obtain paclitaxel. In particular, response surface methodology was used to optimize the factors of fractional precipitation (methanol concentration, material-to-solvent ratio, and precipitating time were optimized as 48.14%, 8.85 mg/mL, and 48.71 h, respectively) and the yield of fractional precipitation product was 30.64 ± 0.60 mg (the content of paclitaxel is 89.3%, 27.37 ± 0.54 mg) from a 100 mg fraction by Al2O3 column separation (the content of paclitaxel is 32.4%). Then, the product was used for further isolation by high-speed countercurrent chromatography. About 1.00 g paclitaxel (200 ± 2 mg in each loading) with a purity up to 99.61% was isolated from 1.25 g of fractional precipitation product with a solvent system of n-hexane/ethyl acetate/methanol/water (1.2:1.8:1.5:1.5, v/v/v/v) in one run of five consecutive sample loadings without exchanging a new solvent system.

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

KEY MESSAGE: 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.

[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.

[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.

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.

[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.

Isolation and characterization of Stemphylium sedicola SBU-16 as a new endophytic taxol-producing fungus from Taxus baccata grown in Iran.

In this study, a total of 25 endophytic fungi were successfully isolated from the inner bark of Taxus baccata grown in Iran by the aseptic technique. Genomic DNA was extracted from isolated endophytic fungi and subjected to polymerase chain reaction (PCR) analysis for the presence of the Taxus taxadiene synthase (ts) gene, which encodes the enzyme catalyzing the first committed step of taxol biosynthesis. Four of 25 isolated endophytic fungi isolates showed PCR positive for the ts gene. Subsequently, taxol and 10-deacetylbaccatin III (10-DAB III) were extracted from culture filtrates and mycelia of the PCR positive isolates and analyzed by high-performance liquid chromatography and mass spectrometry. The analysis showed that one isolate (SBU-16) produced taxol (6.9 ± 0.2 µg L(-1) ) and its intermediate compound, 10-DAB III (2.2 ± 0.1 µg L(-1) ). The isolate SBU-16 was identified as Stemphylium sedicola SBU-16, according to its morphological characteristics as well as the internal transcribed spacer nuclear rDNA gene sequence analysis. Interestingly, this is the first report of the genus Stemphylium as a taxol-producing taxon.