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PubMed2001

[Studies on polysaccharide alkaloids and minerals from Dendrobium moniliforme (L.) Sw].

OBJECTIVE: To explore contents of active substances in different part of Dendrobium monilifrome and the quality influenced by different drying processes. METHOD: Contents of alkaloids and polysaccharides in upper, middle, lower-stem and root part of Dendrobium moniliforme were determined by uv-spectrophotometer method. Contents of essential trace elements were determined by ICP method. RESULT: Contents of polysaccharides and alkaloids were highest in the upper-stem of D. montiliforme. Contents of active substances in different part of D. moniliforme were unequal. Distributions of polysaccharides and alkaloids in different parts were greatly influenced by drying procedures. CONCLUSION: Dendrobium moniliforme has higher contents of active ingredients, such as essential tract elements, alkaloids and polysaccharides. The ideal drying process after harvesting is to be the way dried by fire at a high temperature and desiccated at a temperature of 60 degreeC.

Alkaloids↗
PubMed2026

Heterologous expression of DobHLH25 from Dendrobium officinale enhances drought tolerance in Arabidopsis.

Drought stress severely constrains the growth, yield, and accumulation of bioactive compounds in Dendrobium officinale (D. officinale), a valuable medicinal orchid, and this challenge is exacerbated under simulated wild cultivation where plants are inevitably exposed to recurring water deficits. Basic helix-loop-helix (bHLH) transcription factors are well-established regulators of plant abiotic stress responses. However, the molecular mechanisms by which bHLH transcription factors respond to drought stress in this species remain largely unknown. In this study, a bHLH transcription factor gene, DobHLH25, was cloned from D. officinale. Phylogenetic analysis revealed that DobHLH25 shares the highest sequence identity with its ortholog in Dendrobium nobile. Additionally, subcellular localization analysis indicated that DobHLH25 is targeted to the nucleus and possesses a functional transcriptional activation domain. Expression pattern analysis showed that DobHLH25 is most abundantly expressed in old leaves, and its expression in roots, stems, and leaves is induced by polyethylene glycol treatments. Heterologous expression of DobHLH25 in Arabidopsis thaliana resulted in higher seed germination rates and longer root lengths under mannitol-induced osmotic stress compared to wild-type plants. Under drought stress, DobHLH25 heterologous expression lines exhibited higher survival rates, reduced leaf water loss, lower malondialdehyde accumulation, and increased proline content. Moreover, the activities of antioxidant enzymes such as superoxide dismutase and peroxidase were significantly enhanced, and the expression levels of multiple drought-responsive genes were markedly upregulated. Collectively, these findings suggest a correlation between DobHLH25 expression and plant drought tolerance, as evidenced by reduced oxidative damage, increased osmolyte accumulation, enhanced antioxidant enzyme activities, and upregulation of drought-responsive genes. Together, these results suggest that DobHLH25 plays a positive role in drought tolerance, and provides a basis for future dissection of its regulatory network in D. officinale.

Drought Resistance↗
PubMed2005

Transgenic resistance to Cymbidium mosaic virus in Dendrobium expressing the viral capsid protein gene.

A Taiwan isolate of Cymbidium mosaic virus (CymMV-CS) was isolated from infected Cymbidium sinesis Willd. The cDNA of the capsid protein (CP) gene was synthesized and sequenced. Alignment of this CP gene with other reported CPs revealed homologies of 92-98% at the nucleotide level and 98-99% at the amino acid level. To generate virus-resistant varieties, the CymMV-CS CP gene was transformed into Dendrobium protocorms through particle bombardment. Transformants were selected on medium supplemented with 20 mg/L hygromycin and the presence of the transgene was confirmed by polymerase chain reaction, Southern, Northern and Western blot analyses. Transgenic Dendrobium harboring the CymMV CP gene expressed a very low level of virus accumulation four months post-inoculation with CymMV, as detected by ELISA. The transgenic plants exhibited much milder symptoms than the non-transgenic plants upon challenge with CymMV virions.

Base Sequence↗
PubMed2005

Thidiazuron influences the endogenous levels of cytokinins and IAA during the flowering of isolated shoots of Dendrobium.

This study reports the effects of thidiazuron (TDZ) on the endogenous levels of indoleacetic acid (IAA), zeatin, zeatin riboside ([9R]Z), isopentenyladenine and isopentenyladenosine ([9R]iP) as well as structural changes in the apical meristem of Dendrobium Second Love shoots during flower induction and initial development in vitro. The results revealed that the presence of 1.8microM TDZ had a profound effect on the endogenous cytokinins (CKs) and IAA levels of the explants, when compared to those grown on a TDZ-free medium. A significant increase in CKs (especially [9R]iP and [9R]Z) and IAA in the first samples (taken at day 5) grown on TDZ-enriched medium was associated with flower induction, while a second increase in the level of these hormones after 25d of culture was related to flower development. The histological changes detected in the shoot apical meristem of explants grown in the presence of 1.8microM TDZ during 30d of culture are also described. Based on these findings, it is suggested that both auxin and CKs seem to be involved with the floral transition of Dendrobium Second Love in vitro. However, a possible direct effect of TDZ on flower formation is not discarded.

Adenosine↗
PubMed2003

Functional characterisation of a cytokinin oxidase gene DSCKX1 in Dendrobium orchid.

Cytokinin oxidase plays an important role in the cytokinin regulatory processes. We have cloned a novel putative cytokinin oxidase, DSCKX1 (Dendrobium Sonia cytokinin oxidase), by mRNA differential display from shoot apices of Dendrobium Sonia cultured in the presence of BA. The DSCKX1 gene appears to have three alternative splicing forms and its expression of DSCKX1 was induced in a tissue-specific manner by cytokinins. In transgenic orchid plants overexpressing DSCKX1, the elevated level of cytokinin oxidase activity was accompanied by a reduction of cytokinin content. These plants exhibited slow shoot growth with numerous and long roots in vitro. Their calli also showed decreased capability of shoot formation. Conversly, antisense transgenic plants showed rapid proliferation of shoots and inhibition of root growth combined with a higher endogenous cytokinin content than wild-type plants. Thus DSCKX1 appears to play an important role on cytokinin metabolism and the related developmental programmes in orchid.

Adenine↗
PubMed2003

Allele-specific primers for diagnostic PCR authentication of Dendrobium officinale.

Based on rDNA ITS sequences of D. officinale and the other 37 species of Dendrobium, a pair of allele-specific diagnostic primers, TP-JB01S and TP-JB01X, were designed to authenticate D. officinale from the other species. Before the diagnostic PCR, the primer pair, P1 and P2, for amplifying the whole ITS region was used to validate template DNA and to obtain the appropriate template DNA for the diagnostic PCR. Diagnostic PCRs were performed using the diagnostic primers with the total DNAs of the original plants as a template. When the annealing temperature was raised to 66 degrees C, only the template DNA of D. officinale could be amplified whereas the diagnostic PCRs of the other Dendrobium species were all negative. The diagnostic PCRs have been repeated many times and have played an important role in authenticating the stems of D. officinale in China. Compared with the authentication method by sequencing DNA fragments, the allele-specific diagnostic PCR is not only simpler and time-saving but also practical and effective.

Alleles↗
PubMed2004

Pseudopollen in Dendrobium unicum Seidenf. (Orchidaceae): reward or deception?

BACKGROUND AND AIMS: In 1987, Kjellsson and Rasmussen described the labellar trichomes of Dendrobium unicum Seidenf. and proposed that these hairs function as pseudopollen. Pseudopollen is a mealy material that superficially resembles pollen, is usually laden with food substances and is formed when labellar hairs either fragment into individual cells or become detached from the labellum. However, the trichomes of D. unicum are very different from pseudopollen-forming hairs found in other orchid genera such as Maxillaria and Polystachya. Moreover, Kjellsson and Rasmussen were unable to demonstrate the presence of food substances within these trichomes and argued that even in the absence of food substances, the hairs, in that they superficially resemble pollen, can still attract insects by deceit. The aim of this paper is to investigate whether the labellar trichomes of D. unicum contain food reserves and thus reward potential pollinators or whether they are devoid of foods and attract insects solely by mimicry. METHODS: Light microscopy, histochemistry and transmission electron microscopy. KEY RESULTS: Dendrobium unicum produces pseudopollen. Pseudopollen here, however, differs from that previously described for other orchid genera in that the pseudopollen-forming trichomes consist of a stalk cell and a 'head' of component cells that separate at maturity, in contrast to Maxillaria and some Polystachya spp. where pseudopollen is formed by the fragmentation of moniliform hairs. Moreover, the pseudopollen of Maxillaria and Polystachya largely contains protein, whereas in D. unicum the main food substance is starch. CONCLUSIONS: Flowers of D. unicum, rather than attracting insects solely by deceit may also reward potential pollinators.

Dendrobium↗
PubMed2001

[Researches on morphology and anatomy of root system of Dendrobium nobile Lindl].

OBJECTIVE: To understand the morphological and anatomical characteristics of Dendrobium nobile so as to provide scientific basis for its domestication and cultivation. METHOD: The root's morphological development and interior structure were investigated. RESULT AND CONCLUSION: Dendrobium has peculiar structure which determines that this plant requires a growing environment with high water and air ventilation properties.

Dendrobium↗
PubMed1999

[Study on cultivation of Dendrobium flexicaule by habitat imitation].

Dendrobium drug, a rare medicinal herb, reproduces differcut for growth environment to lead rare resources. By studying of cultivation for many many years in Fuliu mountain area, authors had found out the cultivated method simulating the habitat of wild Dendrobium flexicaule. The results could supply a basis for its development and utilization.

Conservation of Natural Resources↗
PubMed2003

[Studies on the chemical constituents of Dendrobium fimbriatum].

AIM: To investigate the chemical constituents of Dendrobium fimbriatum Hook. METHODS: Various chromatographic techniques were employed for isolation and purification of the constituents. The structures were elucidated by IR, MS, 1HNMR, 13CNMR and 2D-NMR. RESULTS: Eight compounds were obtained and identified by spectral analysis as fimbriatone, confusarin, crepidatin, physcion, rhein, ayapin, scopolin methyl ether and n-octacostyl ferulate. CONCLUSION: Fimbriatone is a new compound, physcion and rhein are firstly isolated from Genus Dendrobium. The others are found from this species for the first time. Fimbriatone showed potential inhibitory effects on BGC cell line.

Anthraquinones↗
PubMed2005

[Location and relative quantity of coumarins in the stem of Dendrobium thyrsiflorum].

AIM: To determine the location and relative quantity of coumarins in the stem of Dendrobium thyrsiflorum Rchb. f. , and to provide a scientific basis for evaluating and utilizing the famous medicinal plant. METHODS: The stems of one, two and three years old, separately, were collected in February. Location and relative quantity of coumarins in the top, middle and basal parts of each stem sample were determined by using laser scanning confocal microscopy (LSCM). ANOVA and Tukey's test were employed in the statistical analysis. RESULTS: The coumarins located mainly in vascular bundles, especially on the walls of the outer fiber cells. There was significant difference or great significant difference exist in every part of the stem from different ages. The values of significant difference were as follows: basal part P = 0.004 (< 0.01); middle part P = 0.009 (< 0.01); top part P = 0.036( < 0.05). CONCLUSION: Two years old stem could be the best choice when collecting Dendrobium thyrsiflorum in Feburary.

Coumarins↗
PubMed2005

[Studies on the growth, chemical components and physiological characteristics of F1 generation of Dendrobium huoshanense].

OBJECTIVE: Through a comparison between F1 and its' parents on the growth, chemical components and physiology, this study aims to find the possibility of selecting new dendrobium hybrids with high yield and good quality. METHOD: To determinate the growth, chemical components, photosynthesis, hormones and isoenzyme in the plants. RESULT: Photosynthetic area, content of chlorophyll, net photosynthesis and yield of F1 generation are higher than those of the parents; chla/b rate is lower; growth is almost the same as in Dendrobium moniliforme; content of chemical components are the same as in D. huoshanense. F1 is approaching of advantages of parents. CONCLUSION: Physiological characters, yield and quality of F1 are greatly improved by hybridization.

Alkaloids↗
PubMed2005

[Determination of polysaccharides of Dendrobium candidum in test-tube culture].

OBJECTIVE: To investigate the diversities of polysaccharides content of Dendrobium candidum and its test-tube culture. METHODS: The content of polysaccharides was determined by colorimentry. RESULTS: The content of polysaccharides extracted from Dendrobium candidum was higher than that of test-tube culture. CONCLUSION: The content of polysaccharides in protocorm is higher than that in test-tube plantlet.

Culture Techniques↗
PubMed2005

[Genetic diversity and molecular authentication of wild populations of Dendrobium officinale by RAPD].

AIM: Genetic diversity, relationship and molecular authentication of total 8 wild populations of Dendrobium officinale were investigated using RAPD markers. METHODS: 10 random decamer primers were screened for Random Amplified Polymophic DNA (RAPD) fragments. A DNA molecular dendrogram was established based on cluster analysis by UPGMA (unweighted pair-group method with arithmetic average), and the relationship of the wild populations were analyzed, and all the wild populations were authenticated. RESULTS: A total of 439 loci with an average of 43.9 loci per primer and 54.9 loci per population were amplified from 8 wild populations by 10 effective primers. In the total 104 amplified bands, 95 were polymorphic, corresponding to 91.35% genetic polymorphism. The genetic distances were 0. 590 to 0. 727, with an average of 0. 686. CONCLUSION: Distinct genetic differences and extensive genetic diversity were presented among the wild populations. RAPD markers were an informative and useful tool for the genetic diversity, evaluation and authentication of wild populations of Dendrobium officinale. Primer S412 could be used to authenticate 8 wild populations completely.

China↗
PubMed2006

[Effect of phosphate on growth and polysaccharide production by suspension cultures of protocorm-like bodies of Dendrobium huoshanense].

The effect of inorganic phosphate on cell growth, accumulation of polysaccharides together with nutrient utilization was investigated in suspension cultures of protocorm-like bodies of Dendrobium huoshanense. Thirty-day-old cells were transferred into liquid medium with the inoculum density of 100 g/L cells. The results indicate that the optimal concentration of phosphate in medium for cell growth of protocorm-like bodies of Dendrobium huoshanense was 2.5 mmol/L and biomass was 496.5 g/L (fresh weight). Phosphate was a limited factor for cell growth and there was relationship between the levels of intracellular phosphate and cell growth. 2.5 mmol/L of medium phosphate was beneficial to the absorption of carbohydrate and nitrate source. 0.312 mmol/L of medium phosphate was better for accumulation of polysaccharides and production of polysaccharides was 2.22 g/L at 36 d.

Cell Proliferation↗
PubMed2002

Authentication of stems of Dendrobium officinale by rDNA ITS region sequences.

The rDNA ITS regions of five Dendrobium species were sequenced. Each Dendrobium species was found to have a unique sequence in the ITS region, so that they could be easily distinguished at the DNA level. The aligned 644 bp of the ITS region includes 235 bp ITS1, 163 bp 5.8S, and 246 bp ITS2. One hundred and eighty-nine sites are variable. The sequences of D. officinale could be easily distinguished from the other four adulterant species according to the sequence variation at 11 sites, 7 in ITS1, 1 in 5.8S, and 3 in ITS2. These could be used as molecular characters to distinguish the stems of D. officinale from the adulterants.

China↗
PubMed1998

[Plantlet strengthening medium for Dendrobium candidum Wall. et Linde. of clonal propagation in vitro].

OBJECTIVE: To find a suitable medium for plantlet production of Dendrobium candidum in the period of strengthening plantlet. METHOD: The basic medium, natural aqueous extracts, density of banana aqueous extract and of plant hormones were tested. RESULTS AND CONCLUSION: The B5 or 1/2MS, added with 10% of banana aqueous extract and 2 mg/L NAA can be used as the best plantlet strengthening medium for Dendrobium candidum.

Culture Media↗