Cold Response Transcriptome Analysis of the Alternative Splicing Events Induced by the Cold Stress in D. catenatum.

Dendrobium catenatum Lindl is a valuable medicinal herb and gardening plant due to its ornamental value and special medical value. Low temperature is a major bottleneck restricting D. catenatum expansion towards the north, which influences the quality and yield of D. catenatum. In this study, we analysed the cold response of D. catenatum by RNA-Seq. A total of 4302 differentially expressed genes were detected under cold stress, which were mainly linked to protein kinase activity, membrane transport and the glycan biosynthesis and metabolism pathway. We also identified 4005 differential alternative events in 2319 genes significantly regulated by cold stress. Exon skipping and intron retention were the most common alternative splicing isoforms. Numerous genes were identified that differentially modulated under cold stress, including cold-induced transcription factors and splicing factors mediated by AS (alternative splicing). GO enrichment analysis found that differentially alternatively spliced genes without differential expression levels were related to RNA/mRNA processing and spliceosomes. DAS (differentially alternative splicing) genes with different expression levels were mainly enriched in protein kinase activity, plasma membrane and cellular response to stimulus. We further identified and cloned DcCBP20 in D. catenatum; we found that DcCBP20 promotes the generation of alternative splicing variants in cold-induced genes under cold stress via genetic experiments and RT-PCR. Taken together, our results identify the main cold-response pathways and alternative splicing events in D. catenatum responding to cold treatment and that DcCBP20 of D. catenatum get involved in regulating the AS and gene expression of cold-induced genes during this process. Our study will contribute to understanding the role of AS genes in regulating the cold stress response in D. catenatum.

Transcriptome and Metabolome Reveal Salt-Stress Responses of Leaf Tissues from Dendrobium officinale.

Dendrobium officinale Kimura et Migo is a precious traditional Chinese medicine. Despite D. officinale displaying a good salt-tolerance level, the yield and growth of D. officinale were impaired drastically by the increasing soil secondary salinization. The molecular mechanisms of D. officinale plants' adaptation to salt stress are not well documented. Therefore, in the present study, D. officinale plants were treated with 250 mM NaCl. Transcriptome analysis showed that salt stress significantly altered various metabolic pathways, including phenylalanine metabolism, flavonoid biosynthesis, and α-linolenic acid metabolism, and significantly upregulated the mRNA expression levels of DoAOC, DoAOS, DoLOX2S, DoMFP, and DoOPR involved in the jasmonic acid (JA) biosynthesis pathway, as well as rutin synthesis genes involved in the flavonoid synthesis pathway. In addition, metabolomics analysis showed that salt stress induced the accumulation of some compounds in D. officinale leaves, especially flavonoids, sugars, and alkaloids, which may play an important role in salt-stress responses of leaf tissues from D. officinale. Moreover, salt stress could trigger JA biosynthesis, and JA may act as a signal molecule that promotes flavonoid biosynthesis in D. officinale leaves. To sum up, D. officinale plants adapted to salt stress by enhancing the biosynthesis of secondary metabolites.

Genome-Wide Identification and Analysis of the APETALA2 (AP2) Transcription Factor in Dendrobium officinale.

The APETALA2 (AP2) transcription factors (TFs) play crucial roles in regulating development in plants. However, a comprehensive analysis of the AP2 family members in a valuable Chinese herbal orchid, Dendrobium officinale, or in other orchids, is limited. In this study, the 14 DoAP2 TFs that were identified from the D. officinale genome and named DoAP2-1 to DoAP2-14 were divided into three clades: euAP2, euANT, and basalANT. The promoters of all DoAP2 genes contained cis-regulatory elements related to plant development and also responsive to plant hormones and stress. qRT-PCR analysis showed the abundant expression of DoAP2-2, DoAP2-5, DoAP2-7, DoAP2-8 and DoAP2-12 genes in protocorm-like bodies (PLBs), while DoAP2-3, DoAP2-4, DoAP2-6, DoAP2-9, DoAP2-10 and DoAP2-11 expression was strong in plantlets. In addition, the expression of some DoAP2 genes was down-regulated during flower development. These results suggest that DoAP2 genes may play roles in plant regeneration and flower development in D. officinale. Four DoAP2 genes (DoAP2-1 from euAP2, DoAP2-2 from euANT, and DoAP2-6 and DoAP2-11 from basal ANT) were selected for further analyses. The transcriptional activation of DoAP2-1, DoAP2-2, DoAP2-6 and DoAP2-11 proteins, which were localized in the nucleus of Arabidopsis thaliana mesophyll protoplasts, was further analyzed by a dual-luciferase reporter gene system in Nicotiana benthamiana leaves. Our data showed that pBD-DoAP2-1, pBD-DoAP2-2, pBD-DoAP2-6 and pBD-DoAP2-11 significantly repressed the expression of the LUC reporter compared with the negative control (pBD), suggesting that these DoAP2 proteins may act as transcriptional repressors in the nucleus of plant cells. Our findings on AP2 genes in D. officinale shed light on the function of AP2 genes in this orchid and other plant species.

Cytological Observation and Transcriptome Comparative Analysis of Self-Pollination and Cross-Pollination in Dendrobium Officinale.

Dendrobium officinale is a rare and traditional medicinal plant with high pharmacological and nutritional value. The self-incompatibility mechanism of D. officinale reproductive isolation was formed in the long-term evolution process, but intraspecific hybridization of different germplasm resources leads to a large gap in the yield, quality, and medicinal value of D. officinale. To investigate the biological mechanism of self-incompatibility in D. officinale, cytological observation and the transcriptome analysis was carried out on the samples of self-pollination and cross-pollination in D. officinale. Results for self-pollination showed that the pollen tubes could grow in the style at 2 h, but most of pollen tubes stopped growing at 4 h, while a large number of cross-pollinated pollen tubes grew along the placental space to the base of ovary, indicating that the self-incompatibility of D. officinale may be gametophyte self-incompatibility. A total of 63.41 G basesum of D. officinale style samples from non-pollinated, self-pollination, and cross-pollination by RNA-seq were obtained, and a total of 1944, 1758, and 475 differentially expressed genes (DEGs) in the comparison of CK (non-pollinated) vs. HF (cross-pollination sample), CK vs. SF (self-pollination sample) and SF vs. HF were identified, respectively. Forty-one candidate genes related to self-incompatibility were found by function annotation of DEGs, including 6 Ca2+ signal genes, 4 armed repeat containing (ARC) related genes, 11 S-locus receptor kinase (SRK) related genes, 2 Exo70 family genes, 9 ubiquitin related genes, 1 fatty acid related gene, 6 amino acid-related genes, 1 pollen-specific leucine-rich repeat extensin-like protein (LRX) related gene and 1 lectin receptor-like kinases (RLKs) related gene, showed that self-incompatibility mechanism of D. officinale involves the interaction of multiple genes and pathways. The results can provide a basis for the study of the self-incompatibility mechanism of D. officinale, and provide ideas for the preservation and utilization of high-quality resources of D. officinale.

Variability of Volatile Compounds in the Medicinal Plant Dendrobium officinale from Different Regions.

Dendrobium officinale Kimura et Migo, a rare and traditional medicinal plant, contains many nutrients such as polysaccharides, alkaloids, amino acids and so on. Different growth environment and intraspecific hybridization of different germplasm resources lead to large differences in the yield, quality and medicinal value of D. officinale. Here, the volatile compounds of D. officinale from four producing regions (Zhejiang, Fujian, Yunnan and Jiangxi) were analyzed to provide a certain reference value for the selection of a specific medicinal component in D. officinale breeding. Fresh stems of D. officinale germplasm resources were collected, and the chemical constituents were determined by gas chromatography-mass spectrometry. A total of 101 volatile compounds were identified, of which esters and alcohols accounted for 23 and 22. Hexacosane is the highest relative content of all volatile components. The highest content of hexacosane was observed in YA1 from Yunnan was 34.41%, and the lowest (23.41%) in JA1 from Jiangxi. Moreover, 5-10 unique substances were determined in different regions. A total of 17 medicinal components were detected, and three unique medicinal components were detected only in YA1, revealing that YA1 can provide raw materials for the application of specific medicinal substances extraction. A total of four toxic components were detected, but no toxic components were detected in JA1 from Jiangxi, suggested that the germplasm resources from Jiangxi could be exploited efficiently for breeding superior D. officinale specimens. The results provide a theoretical basis for the collection, protection and utilization of D. officinale germplasm resources in different regions.

DoRWA3 from Dendrobium officinale Plays an Essential Role in Acetylation of Polysaccharides.

The acetylation or deacetylation of polysaccharides can influence their physical properties and biological activities. One main constituent of the edible medicinal orchid, Dendrobium officinale, is water-soluble polysaccharides (WSPs) with substituted O-acetyl groups. Both O-acetyl groups and WSPs show a similar trend in different organs, but the genes coding for enzymes that transfer acetyl groups to WSPs have not been identified. In this study, we report that REDUCED WALL ACETYLATION (RWA) proteins may act as acetyltransferases. Three DoRWA genes were identified, cloned, and sequenced. They were sensitive to abscisic acid (ABA), but there were no differences in germination rate and root length between wild type and 35S::DoRWA3 transgenic lines under ABA stress. Three DoRWA proteins were localized in the endoplasmic reticulum. DoRWA3 had relatively stronger transcript levels in organs where acetyl groups accumulated than DoRWA1 and DoRWA2, was co-expressed with polysaccharides synthetic genes, so it was considered as a candidate acetyltransferase gene. The level of acetylation of polysaccharides increased significantly in the seeds, leaves and stems of three 35S::DoRWA3 transgenic lines compared to wild type plants. These results indicate that DoRWA3 can transfer acetyl groups to polysaccharides and is a candidate protein to improve the biological activity of other edible and medicinal plants.

Rapid propagation in vitro and accumulation of active substances of endangered Dendrobium cariniferum Rchb. f.

Dendrobium cariniferum is a valuable ornamental and medicinal plant rich with polysaccharides, alkaloid, and other bioactive compounds, which are potential raw materials for pharmacological utilization. In this study, an efficient protocol for the rapid propagation of D. cariniferum was developed. By using the tissue culture protocol, the effects of pH, hormone combinations, temperatures, light intensity, culture time protocorm proliferation, seedlings rooting, and accumulation of biomass with bioactive compounds were investigated. The experiments showed that the medium [1/2 MS + activated carbon1.0 g/L+ agar strip 7.5 g/L + sucrose 25 g/L] effectively promoted the germination of D. cariniferum seeds. The optimal culture conditions were found at pH 5.7, temperature 23 ± 2°C, and light intensity of 1000 Lx in the protocorm proliferation stage. Adding 1.5 g/L peptone in the medium effectively promoted the seedling rooting. The optimal culture conditions for accumulation of bioactive compounds (polysaccharides and alkaloids) of seedlings were found at temperature of 25 ± 2°C, light intensity of 1500-2000 Lx after the 60-day (d). Our study constructed a rapid propagation system in vitro for D. cariniferum, as well as the methods for efficient accumulation of active substances in seedling culture, which will serve as guidance for industrial production of D. cariniferum seedlings for both medicinal raw materials and ornamental plants. In addition, our study provided a new idea that we can directly use the high bioactive compound seedlings to extract medicinal components in industry conditions without transferring to the field.

Transcriptome Analysis Reveals Biosynthesis of Important Bioactive Constituents and Mechanism of Stem Formation of Dendrobium huoshanense.

The stem of Dendrobium huoshanense C.Z. Tang and S.J. Cheng was widely used as a medicinal herb in health care products due to its broad pharmacological activities. However, the molecular regulation mechanism of stem development and biosynthetic pathways of important bioactive substances are still unclear in D. huoshanense. In this study, the bioactive compounds in leaves, stems and roots, and the identification of candidate genes involved in stem formation and biosynthesis of active compounds via transcriptome sequence were analyzed. The accumulation of total polysaccharides and flavonoids were varied significantly in different tissues. A comparative transcriptomic analysis revealed several differentially expressed genes (DEGs) involved in polysaccharides biosynthesis (103 genes), including fructose and mannose related genes (29 genes) and glycosyltransferase genes (74 genes), and flavonoids biosynthesis (15 genes). Some candidate genes that participated in photoperiod regulation (27 genes), starch and sucrose metabolism (46 genes), and hormone-induced activation of signaling pathways (38 genes) may be involved in stem formation. In sum, this study provides a foundation for investigating the molecular processes in the biosynthesis of active compounds and stem development. The transcriptome data presented here provides an important resource for the future studies of the molecular genetics and functional genomics in D. huoshanense and optimized control of the active compounds produced by D. huoshanense.

Comparative nutritional characteristics of the three major Chinese Dendrobium species with different growth years.

Dendrobium, an important medicinal plant, is a source of widely used herbal medicine to nourish the stomach and treat throat inflammation. The present study is aimed at distinguishing and evaluating three major Dendrobium species by comparing physiochemical characteristics and understanding differences between different growth years in the Ta-pieh Mountains. Polysaccharides and total alkaloids of Dendrobium were determined, and the amino acids and trace elements were determined by UPLC (Ultra High-Performance Liquid Chromatography) and ICP-MS (Inductively coupled plasma mass spectrometry). It can be seen from the results that the polysaccharide content of these three kinds of Dendrobium in different growth years ranges from 249.31 mg·g-1 to 547.66 mg·g-1, and the highest content is in the 3-year-old Dendrobium huoshanense. The total alkaloid content ranges from 0.21 mg·g-1 to 0.54 mg·g-1, and the highest content is also the 3-year-old Dendrobium huoshanense. We determined the amino acid content of these three Dendrobium in different growth years, and we can see that each of the three kinds of Dendrobium contain seven kinds of amino acids required by the human body. We conducted a safety evaluation of the essential trace elements of Dendrobium, and the results showed that the dosage of 12g·d-1 Dendrobium prescribed in China Pharmacopoeia is in accordance with the recommended daily intake of trace elements recommended by the Food and Drug Administration of the United States, and will not cause trace element poisoning. Linear discriminant analysis was carried out on the basis of amino acids and trace elements and confirmed the applicability of multi-elemental analysis for identifying different Dendrobium species.

[Investigation and application of Dendrobium resources in Qinba Mountains with a discussion on industrial poverty alleviation model].

The Dendrobium species are rare and endangered medicinal plants, and it is difficult to investigate their wild resources with conventional methods because of typical epiphytic herbaceous. We explored Dendrobium resources(include culture resource) of Qinba Mountains and the boundary Mountain area in Hubei, Chongqing using the methods of literatures and field investigation, and found that the cultural base of Dendrobium were profound in Qinba Mountains region. Furthermore, its germplasm resources of Dendrobium were established for the first time in Wanzhou Luotian town. In case the advantages of local rock resources and poverty alleviation demand, we have actively carried out the cultivating mode of Dendrobium which grow on rock, and the poverty alleviation model of local characteristic Dendrobium industry were established preliminarily. Our application case can provide reference for the mining and transformation of traditional Chinese medicine resources census results.

The GDP-mannose transporter gene (DoGMT) from Dendrobium officinale is critical for mannan biosynthesis in plant growth and development.

Dendrobium officinale is a precious traditional Chinese medicinal herb because it is abundant in mannose-containing polysaccharides (MCPs). GDP-mannose transporter (GMT), which translocates GDP-mannose into the Golgi lumen, is indispensable for the biosynthesis of MCPs. In this study, we found that the dominant polysaccharides in D. officinale were MCPs in a range of varieties and different physiological phases. After a positive correlation between the accumulation of mannose and the transcript levels of candidate GMT genes was found, three GMT genes (DoGMT1-3) were identified in D. officinale. DoGMT1, DoGMT2 and DoGMT3 exhibited the highest transcript level in stem that an organ for MCPs storage. All three DoGMT proteins were targeted to Golgi apparatus, and had a GDP binding domain (GXL/VNK) that was homologous to a specially characterized GMT protein GONST1 in Arabidopsis thaliana. Moreover, DoGMT1, DoGMT2 and DoGMT3 complemented a GDP-mannose transport-defective yeast mutant (vrg4-2), meanwhile they also demonstrated a higher GDP-mannose uptake activity. Therefore, we conclude that DoGMT1, DoGMT2 and DoGMT3 are able to transport GDP-mannose while the expression patterns of these genes correspond to the accumulation of MCPs in D. officinale. These findings support the importance of GMT genes from D. officinale in the biosynthesis of MCPs.

Structural Characterization of Polysaccharides from Dendrobium officinale and Their Effects on Apoptosis of HeLa Cell Line.

Dendrobium officinale is a widely used medicinal plant in China with numerous bio-activities. However, the main structure and anti-tumor activity of the polysaccharides from this plant have not been investigated. In this study, we elucidated the main structure of polysaccharides purified with DEAE and Sephadex G-25 from Dendrobium officinale grown under different planting conditions. In addition, the anti-tumor activity was tested via MTT assays. The results showed that the polysaccharides of Dendrobium officinale grown under different conditions were almost the same, with slight differences in the branched chain; both polysaccharide fractions consisted of (1→4)-linked mannose and (1→4)-linked glucose, with an O-acetyl group in the mannose. After degradation, the polysaccharide fractions from wild plants showed significant anti-proliferation activity in HeLa cells. The fractions F1 and F3 induced apoptosis by up-regulating the expression of ERK, JNK, and p38. We concluded that polysaccharides from Dendrobium officinale planted in the wild exhibit significant anti-tumor effects only after being degraded to smaller molecular weight species. The planting mode is a significant factor in the pharmacological activity of Dendrobium officinale. We advise that the planting conditions for Dendrobium officinale should be changed.

[Effects of cultivation environments on Dendrobium catenatum].

The study was aimed to clarify the effect of three cultivation environments on the growth and metabolism of Dendrobium catenatum C13 group. There were three different cultivation conditions including rock epiphytic cultivation, pear epiphytic cultivation and pot cultivation. Morphological characteristics and agronomic characters of D. catenatum were observed and measured. Microstructure, contents of polysaccharide and alcohol-soluble extracts were measured by paraffin section method, phenol-sulfuric acid method and hot-dip method, respectively. The result showed that the cultivation environment significantly affected the growth of D. catenatum, the leaves of D. catenatum that cultivated on the rock and pear were sparse and small, the stems were short and purple and the root system was developed. Compare with potted cultivation, D. catenatum from rock epiphytic cultivation and pear epiphytic cultivation showed the following characteristics in the microstructure: the upper epidermis became thicker, the epidermal hair in the epidermis became denser, stomatal showed smaller and denser, the cell wall of exodermis, endoderm and medulla became thicker, the cell of velamen, exodermis, endoderm and medulla were smaller and arranged more closely, but the cultivation environment did not produce specific tissue structure, mainly changed in the structural parameters of size and quantity. The growth environments also influenced contents of polysaccharides and alcohol-soluble extracts. The dontents of polysaccharides and alcohol-soluble extracts in D. catenatum from rock epiphytic were the highest, reached 37.34% and 11.66%, the second was pear epiphytic, both higher than pot cultivation, alcohol-soluble extracts contents in D. catenatum from rock epiphytic are more complex, which shows that rock epiphytic is conducive to the accumulation of secondary metabolites in D. catenatum.

Molecular cloning and functional analysis of the phosphomannomutase (PMM) gene from Dendrobium officinale and evidence for the involvement of an abiotic stress response during germination.

Phosphomannomutase (PMM, EC 5.4.2.8) catalyzes the interconversion of mannose-6-phosphate to mannose-1-phosphate, the precursor for the synthesis of GDP-mannose. In this study, the complementary DNA (cDNA) of the Phosphomannomutase (PMM) gene was initially cloned from Dendrobium officinale by RACE method. Transient transform result showed that the DoPMM protein was localized in the cytoplasm. The DoPMM gene was highly expressed in the stems of D. officinale both in vegetative and reproductive developmental stages. The putative promoter was cloned by TAIL-PCR and used for searched cis-elements. Stress-related cis-elements like ABRE, TCA-element, and MBS were found in the promoter regions. The DoPMM gene was up-regulated after treatment with abscisic acid, salicylic acid, cold, polyethylene glycol, and NaCl. The total ascorbic acid (AsA) and polysaccharide content in all of the 35S::DoPMM Arabidopsis thaliana transgenic lines #1, #2, and #5 showed a 40, 39, and 31% increase in AsA and a 77, 22, and 39% increase in polysaccharides, respectively more than wild-type (WT) levels. All three 35S::DoPMM transgenic lines exhibited a higher germination percentage than WT plants when seeded on half-strength MS medium supplemented with 150 mM NaCl or 300 mM mannitol. These results provide genetic evidence for the involvement of PMM genes in the biosynthesis of AsA and polysaccharides and the mediation of PMM genes in abiotic stress tolerance during seed germination in A. thaliana.

Metabolic Analysis of Medicinal Dendrobium officinale and Dendrobium huoshanense during Different Growth Years.

Metabolomics technology has enabled an important method for the identification and quality control of Traditional Chinese Medical materials. In this study, we isolated metabolites from cultivated Dendrobium officinale and Dendrobium huoshanense stems of different growth years in the methanol/water phase and identified them using gas chromatography coupled with mass spectrometry (GC-MS). First, a metabolomics technology platform for Dendrobium was constructed. The metabolites in the Dendrobium methanol/water phase were mainly sugars and glycosides, amino acids, organic acids, alcohols. D. officinale and D. huoshanense and their growth years were distinguished by cluster analysis in combination with multivariate statistical analysis, including principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). Eleven metabolites that contributed significantly to this differentiation were subjected to t-tests (P<0.05) to identify biomarkers that discriminate between D. officinale and D. huoshanense, including sucrose, glucose, galactose, succinate, fructose, hexadecanoate, oleanitrile, myo-inositol, and glycerol. Metabolic profiling of the chemical compositions of Dendrobium species revealed that the polysaccharide content of D. huoshanense was higher than that of D. officinale, indicating that the D. huoshanense was of higher quality. Based on the accumulation of Dendrobium metabolites, the optimal harvest time for Dendrobium was in the third year. This initial metabolic profiling platform for Dendrobium provides an important foundation for the further study of secondary metabolites (pharmaceutical active ingredients) and metabolic pathways.

[Advance in molecular biology of Dendrobium (Orchidaceae)].

With the development of molecular biology, the process in molecular biology research of Dendrobium is going fast. Not only did it provide new ways to identify Dendrobium quickly, reveal the genetic diversity and relationship of Dendrobium, but also lay the vital foundation for explaining the mechanism of Dendrobium growth and metabolism. The present paper reviews the recent process in molecular biology research of Dendrobium from three aspects, including molecular identification, genetic diversity and functional genes. And this review will facilitate the development of this research area and Dendrobium.

[Ecological basis of epiphytic Dendrobium officinale growth on cliff].

In order to make Dendrobium officinale return to the nature, the temperature and humidity in whole days of the built rock model with different slopes and aspects in the natural distribution of wild D. officinale in Tianmu Mountain were recorded by MH-WS01 automatic recorder. The results showed that the slope has a significant impact on the extreme temperature on the surface of the rocks. In summer, the extreme temperature on the surface of horizontal or soft rock can reach to 69.4 ℃, while the temperatures were lower than 50 ℃ on the vertical rock. In winter, the temperatures on the surface of vertical rock were higher and the low temperature duration was shorter than those on the horizontal or soft rock. Also, the humidity of the rocks was significantly influenced by the slope. The monthly average humidity on the surface of vertical rock was above 80%RH. Furthermore, the aspect had a significant impact on the temperature and humidity on the surface of the rocks, but had no significant effect on the daily mean temperature and extreme temperature on the surface of vertical rock. Therefore, the slope affects the survival of D. officinale by affecting the extreme temperature of rocks and affects the growth of D. officinale by affecting the humidity. The choice of slope is the key to the success of cliff epiphytic cultivation for D. officinale.

[Effects of endophytic fungi from Dendrobium officinale on host growth and components metabolism of tissue culture seedlings].

The paper aims to study the effects of endophytic fungi from D. officinale cultivated on living trees on growth and components metabolism of tissue culture seedlings. Morphological characteristics and agronomic characters of tissue culture seedlings infected and uninfected by endophytic fungus were observed and measured. Polysaccharides and alcohol-soluble extracts contents were determined by phenol-sulfuric acid method and hot-dipmethod, respectively. Monosacchride composition of polysaccharides and alcohol-soluble extracts components were analyzed by pre-column derivatives HPLC and HPLC method, respectively. It showed that effects of turning to purple of stem nodes could be changed by endophytic fungus. Besides, the endophytic fungus could affect the contents and constitutions of polysaccharides and alcohol-soluble extracts. The strains tested, expect DO34, could promote growth and polysaccharides content of tissue culture seedlings. The strains tested, expect DO12, could promote the accumulation of mannose. Furthermore, DO18, DO19 and DO120 could increase alcohol-soluble extracts. On the basis, four superior strains were selected for mechanism research between endophytic fungus and their hosts and microbiology engineering.

[Effects of different endophytic fungi on seedling growth of Dendrobium devonianum].

To obtain seedling growth-promoting fungi is a key step in restoration-friendly cultivation of medicinal Dendrobium species, since there are a large number of functionally-unknown endophytic fungi in the roots of Dendrobium plants.In this study, six functionally-unknown endophytic fungal strains were isolated from roots of D.devonianum using single peleton isolation technology, and used in inoculation experiments to test their effectiveness for seedling growth in D.devonianum.After 90 days of inoculation, comparing with the control treatment, FDdS-1, FDdS-2 and FDdS-4 showed strong pathogenic or fatal effects on seedlings; while, FDdS-12, FDdS-9 and FDdS-5 had different effects on seedling growth.FDdS-5 had significant promoting effects on height, fresh and dry weight, stem diameter and root numbers, while FDdS-9 only had significant promoting effect on seedling height, and FDdS-12 had a negative effect on seedling growth.According to the anatomical features of the inoculated roots, FDdS-5 fungi could infect the velamina of seedlings and the existence of symbiosis pelotons in the cortex cells, suggesting that FDdS-5 is a mycorrhiza fungi of D.devonianum.FDdS-5 and FDdS-9 were identified as Sebacina vermifera and Sebacina sp.by molecular technologies.By using FDdS-5 in the restoration-friendly cultivation of D.devonianum, it could effectively promote seedling growth and shorten the seedling growth periods.The results will aid in reintroduction and cultivation of D.devonianum.

[Dendrobium officinale cliff epiphytic cultivation method].

To solve the issues of costly planting of facility cultivation method and inferior efficacy than wild herbs of Dendrobium officinale, the cliff epiphytic cultivation method was studied. To research the growth, agronomic traits, yield, polysaccharide and alcohol-soluble extract contents were measured on the D. officinale from different water regulation and cliff slope gradients treatments. The results showed that D. officinale epiphytic at 85 degrees-90 degrees cliff and sprayed water 1-2 h x d(-1) at the growing season can get better growth and obtain high yield, and the morphology has no different from wild cliff D. officinale, even in the environments without shade. The contents of polysaccharide and alcohol-soluble extract are closely related to the physiological ages, but significantly higher than the facility cultivation. It is possible that environmental stresses benefit the accumulation of polysaccharides, alcohol-soluble extract and other efficient ingredients.