High light triggers flavonoid and polysaccharide synthesis through DoHY5-dependent signaling in Dendrobium officinale.

Dendrobium officinale is edible and has medicinal and ornamental functions. Polysaccharides and flavonoids, including anthocyanins, are important components of D. officinale that largely determine the nutritional quality and consumer appeal. There is a need to study the molecular mechanisms regulating anthocyanin and polysaccharide biosynthesis to enhance D. officinale quality and its market value. Here, we report that high light (HL) induced the accumulation of polysaccharides, particularly mannose, as well as anthocyanin accumulation, resulting in red stems. Metabolome and transcriptome analyses revealed that most of the flavonoids showed large changes in abundance, and flavonoid and polysaccharide biosynthesis was significantly activated under HL treatment. Interestingly, DoHY5 expression was also highly induced. Biochemical analyses demonstrated that DoHY5 directly binds to the promoters of DoF3H1 (involved in anthocyanin biosynthesis), DoGMPP2, and DoPMT28 (involved in polysaccharide biosynthesis) to activate their expression, thereby promoting anthocyanin and polysaccharide accumulation in D. officinale stems. DoHY5 silencing decreased flavonoid- and polysaccharide-related gene expression and reduced anthocyanin and polysaccharide accumulation, whereas DoHY5 overexpression had the opposite effects. Notably, naturally occurring red-stemmed D. officinale plants similarly have high levels of anthocyanin and polysaccharide accumulation and biosynthesis gene expression. Our results reveal a previously undiscovered role of DoHY5 in co-regulating anthocyanin and polysaccharide biosynthesis under HL conditions, improving our understanding of the mechanisms regulating stem color and determining nutritional quality in D. officinale. Collectively, our results propose a robust and simple strategy for significantly increasing anthocyanin and polysaccharide levels and subsequently improving the nutritional quality of D. officinale.

DhuFAP: a platform for gene functional analysis in Dendrobium huoshanense.

BACKGROUND: Dendrobium huoshanense, a traditional medicinal and food plant, has a rich history of use. Recently, its genome was decoded, offering valuable insights into gene function. However, there is no comprehensive gene functional analysis platform for D. huoshanense. RESULT: To address this, we created a platform for gene function analysis and comparison in D. huoshanense (DhuFAP). Using 69 RNA-seq samples, we constructed a gene co-expression network and annotated D. huoshanense genes by aligning sequences with public protein databases. Our platform contained tools like Blast, gene set enrichment analysis, heatmap analysis, sequence extraction, and JBrowse. Analysis revealed co-expression of transcription factors (C2H2, GRAS, NAC) with genes encoding key enzymes in alkaloid biosynthesis. We also showcased the reliability and applicability of our platform using Chalcone synthases (CHS). CONCLUSION: DhuFAP ( www.gzybioinformatics.cn/DhuFAP ) and its suite of tools represent an accessible and invaluable resource for researchers, enabling the exploration of functional information pertaining to D. huoshanense genes. This platform stands poised to facilitate significant biological discoveries in this domain.

Physiological and transcriptomic comparisons shed light on the cold stress response mechanisms of Dendrobium spp.

BACKGROUND: Dendrobium spp. comprise a group of tropical orchids with ornamental and medicinal value. Dendrobium spp. are sensitive to low temperature, and the underlying cold response regulatory mechanisms in this group are unclear. To understand how these plants respond to cold stress, we compared the transcriptomic responses of the cold-tolerant cultivar 'Hongxing' (HX) and the cold-sensitive cultivar 'Sonia Hiasakul' (SH) to cold stress. RESULTS: Chemometric results showed that the physiological response of SH in the later stages of cold stress is similar to that of HX throughout the cold treatment. Orthogonal partial least squares discriminant analysis (OPLS-DA) revealed that soluble protein content and peroxidase activity are key physiological parameters for assessing the cold tolerance of these two Dendrobium spp. cultivars. Additionally, weighted gene co-expression network analysis (WGCNA) results showed that many cold response genes and metabolic pathways significantly associated with the physiological indices were enriched in the 12 detected modules. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) enrichment analyses of the 105 hub genes showed that Dendrobium spp. adapt to cold stress by regulating signal transduction, phytohormones, transcription factors, protein translation and modification, functional proteins, biosynthesis and metabolism, cell structure, light, and the circadian clock. Hub genes of the cold stress response network included the remorin gene pp34, the abscisic acid signaling pathway-related genes PROTEIN PHOSPATASE 2 C (PP2C), SNF1-RELATED PROTEIN KINASE 2 (SnRK2), ABRE-BINDING FACTOR 1 (ABF1) and SKI-INTERACTING PROTEIN 17 (SKIP17), the Ca2+ signaling-related GTP diphosphokinase gene CRSH1, the carbohydrate-related gene STARCH SYNTHASE 2 (SS2), the cell wall biosynthesis gene CINNAMYL ALCOHOL DEHYDROGENASE (CAD7), and the endocytosis-related gene VACUOLAR PROTEIN SORTING-ASSOCIATED PROTEIN 52 A (VPS52A). CONCLUSIONS: The cold-responsive genes and metabolic pathways of Dendrobium spp. revealed in this study provide important insight to enable the genetic enhancement of cold tolerance in Dendrobium spp., and to facilitate cold tolerance breeding in related plants.

Genome-wide identification of Ankyrin (ANK) repeat gene families in three Dendrobium species and the expression of ANK genes in D. officinale under gibberellin and abscisic acid treatments.

BACKGROUND: Dendrobium Sw. represents one of the most expansive genera within the Orchidaceae family, renowned for its species' high medicinal and ornamental value. In higher plants, the ankyrin (ANK) repeat protein family is characterized by a unique ANK repeat domain, integral to a plethora of biological functions and biochemical activities. The ANK gene family plays a pivotal role in various plant physiological processes, including stress responses, hormone signaling, and growth. Hence, investigating the ANK gene family and identifying disease-resistance genes in Dendrobium is of paramount importance. RESULTS: This research identified 78 ANK genes in Dendrobium officinale Kimura et Migo, 77 in Dendrobium nobile Lindl., and 58 in Dendrobium chrysotoxum Lindl. Subsequently, we conducted comprehensive bioinformatics analyses on these ANK gene families, encompassing gene classification, chromosomal localization, phylogenetic relationships, gene structure and motif characterization, cis-acting regulatory element identification, collinearity assessment, protein-protein interaction network construction, and gene expression profiling. Concurrently, three DoANK genes (DoANK14, DoANK19, and DoANK47) in D. officinale were discerned to indirectly activate the NPR1 transcription factor in the ETI system via SA, thereby modulating the expression of the antibacterial PR gene. Hormonal treatments with GA3 and ABA revealed that 17 and 8 genes were significantly up-regulated, while 4 and 8 genes were significantly down-regulated, respectively. DoANK32 was found to localize to the ArfGAP gene in the endocytosis pathway, impacting vesicle transport and the polar movement of auxin. CONCLUSION: Our findings provide a robust framework for the taxonomic classification, evolutionary analysis, and functional prediction of Dendrobium ANK genes. The three highlighted ANK genes (DoANK14, DoANK19, and DoANK47) from D. officinale may prove valuable in disease resistance and stress response research. DoANK32 is implicated in the morphogenesis and development of D. officinale through its role in vesicular transport and auxin polarity, with subcellular localization studies confirming its presence in the nucleus and cell membrane. ANK genes displaying significant expression changes in response to hormonal treatments could play a crucial role in the hormonal response of D. officinale, potentially inhibiting its growth and development through the modulation of plant hormones such as GA3 and ABA.

Genomic identification and expression analysis of acid invertase (AINV) gene family in Dendrobium officinale Kimura et Migo.

BACKGROUND: Dendrobium officinale Kimura et Migo, a renowned traditional Chinese orchid herb esteemed for its significant horticultural and medicinal value, thrives in adverse habitats and contends with various abiotic or biotic stresses. Acid invertases (AINV) are widely considered enzymes involved in regulating sucrose metabolism and have been revealed to participate in plant responses to environmental stress. Although members of AINV gene family have been identified and characterized in multiple plant genomes, detailed information regarding this gene family and its expression patterns remains unknown in D. officinale, despite their significance in polysaccharide biosynthesis. RESULTS: This study systematically analyzed the D. officinale genome and identified four DoAINV genes, which were classified into two subfamilies based on subcellular prediction and phylogenetic analysis. Comparison of gene structures and conserved motifs in DoAINV genes indicated a high-level conservation during their evolution history. The conserved amino acids and domains of DoAINV proteins were identified as pivotal for their functional roles. Additionally, cis-elements associated with responses to abiotic and biotic stress were found to be the most prevalent motif in all DoAINV genes, indicating their responsiveness to stress. Furthermore, bioinformatics analysis of transcriptome data, validated by quantitative real-time reverse transcription PCR (qRT-PCR), revealed distinct organ-specific expression patterns of DoAINV genes across various tissues and in response to abiotic stress. Examination of soluble sugar content and interaction networks provided insights into stress release and sucrose metabolism. CONCLUSIONS: DoAINV genes are implicated in various activities including growth and development, stress response, and polysaccharide biosynthesis. These findings provide valuable insights into the AINV gene amily of D. officinale and will aid in further elucidating the functions of DoAINV genes.

Optimizing nutrient solution for vegetative growth of Dendrobium Tubtim Siam and Phalaenopsis Taisuco Swan through plant tissue nutrient balance estimation.

BACKGROUND: Orchids are grown without soil in many regions of the world, but there is a lack of studies to define the balanced and adequate nutrient solution for their cultivation, mainly in the vegetative growth phase. Therefore, this paper aims to evaluate the optimal concentration of the nutrient solution based on the proposal by Hoagland and Arnon (1950) in the vegetative growth phase capable of increasing the nutrient contents, growth, and dry matter production of Dendrobium Tubtim Siam and Phalaenopsis Taisuco Swan. In addition, this paper aims to estimate a new nutrient solution from the optimal nutrient contents in the dry matter of these orchid species to be used in the vegetative growth phase. RESULTS: Nutrient contents, growth, and dry matter production increased as the nutrient solution concentration increased up to an average concentration of 62 and 77% for D. Tubtim Siam and P. Taisuco Swan, respectively. We found that the Hoagland and Arnon solution presented a group of nutrients with concentrations above the requirement for P. Taisuco Swan (nitrogen, phosphor, calcium, and sulfur) and D. Tubtim Siam (phosphor, calcium, magnesium, and sulfur), while other nutrients in the solution did not meet the nutritional demand of these orchid species, inducing nutritional imbalance in the vegetative growth phase. CONCLUSION: We conclude that using a balanced nutrient solution created specifically for each orchid species in vegetative growth might favor their sustainable cultivation by optimizing the use of nutrients in the growing medium.

Bibenzyl and naphthalene derivatives from Dendrobium chrysanthum and their anti-hepatic-steatosis activities.

In this study, 16 new compounds, six bibenzyls (1-6) and 10 naphthalenes (7-13), including three pairs of naphthalene enantiomers and three known compounds (14-16), were isolated from Dendrobium chrysanthum. Structurally, compounds 1-5 are previously undescribed dimeric bibenzyls, uniquely linked by unusual carbon bonds. The structures of the compounds were determined using spectroscopy and X-ray crystallography. The screening results indicated that 1, 2, and 5 showed remarkable lipid-lowering activities in FFA-induced HepG2 cells, with EC50 values ranging from 3.13 to 6.57 µM. Moreover, 1, 2, and 5 significantly decreased both the mRNA and protein levels of the target SREBP-1c, and 5 also reduced PPARα mRNA and protein levels. Therefore, 1, 2, and 5 are potential drugs against hepatic steatosis by targeting PPARα or SREBP-1c.

Visualization of the Infection and Colonization Process of Dendrobium officinale Using a Green Fluorescent Protein-Tagged Isolate of Fusarium oxysporum.

Dendrobium officinale soft rot is a widespread and destructive disease caused by Fusarium oxysporum that can seriously affect yield and quality. To better understand the fungal infection and colonization, we successfully created an F. oxysporum labeled with green fluorescent protein using the Agrobacterium tumefaciens-mediated transformation method. Transformants had varying fluorescence intensities, but their pathogenicity did not differ from that of the wild type. Fluorescence microscopy revealed that F. oxysporum primarily entered the aboveground portion of D. officinale through the leaf margin, stomata, or by direct penetration of the leaf surface. It then colonized the mesophyll and spread along its vascular bundles. D. officinale exhibited typical symptoms of decay and wilting at 14 days postinoculation, accompanied by a pronounced fluorescence signal in the affected area. The initial colonization of F. oxysporum in the subterranean region primarily involved attachment to the root hair and epidermis, which progressed to the medullary vascular bundle. At 14 days postinoculation, the root vascular bundles of D. officinale exhibited significant colonization by F. oxysporum. Macroconidia were also observed in black rot D. officinale tissue. In particular, the entire root was surrounded by a significant number of chlamydospore-producing F. oxysporum mycelia at 28 days postinoculation. This approach allowed for the visualization of the complete infection process of F. oxysporum and provided a theoretical foundation for the development of field control strategies.

Dendrobium polysaccharide (DOP) ameliorates the LL-37-induced rosacea by inhibiting NF-κB activation in a mouse model.

BACKGROUND: Rosacea, a common chronic inflammatory skin disease worldwide, is currently incurable with complex pathogenesis. Dendrobium polysaccharide (DOP) may exert therapeutic effects on rosacea via acting on the NF-κB-related inflammatory and oxidative processes. MATERIALS AND METHODS: In this study, an LL-37-induced rosacea-like mouse model was established. HE staining was used to assess the skin lesions, erythema severity scores, pathological symptoms, and inflammatory cell numbers of mice in each group. The inflammation level was quantitatively analyzed using enzyme-linked immunosorbent assay (ELISA) and reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR). The expression levels of TLR4 and p-NF-κB were finally detected. RESULTS: DOP improved skin pathological symptoms of rosacea mice. DOP also alleviated the inflammation of rosacea mice. Moreover, the TLR4/NF-κB pathway was observed to be inhibited in the skin of mice after DOP application. These findings evidenced the anti-inflammatory effects of DOP on the LL-37-induced rosacea mouse model. DOP could inhibit NF-κB activation, suppress neutrophil infiltration, and reduce pro-inflammatory cytokines production, which may be the reason for DOP protecting against rosacea. CONCLUSION: This study may propose an active candidate with great potential for rosacea drug development and lay a solid experimental foundation for promoting DOP application in rosacea therapy.

Antioxidant and L-asparaginase activities of culturable endophytic fungi from ornamental Dendrobium orchids.

This study reports the antioxidant potential and L-asparaginase production of culturable fungal endophytes from Dendrobium orchids in Malaysia. Twenty-nine isolates were screened using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay to determine their free radical scavenging activities and antioxidant capacity (IC50 and AEAC). L-asparaginase production of fungal endophytes was detected by the qualitative plate assay, and the enzyme activities estimated via the Nesslerization method. All 29 endophytic isolates exhibited various degrees of radical scavenging activities (35.37%-77.23%), with Fusarium fujikuroi (D1) identified as having the highest antioxidant capacity (IC50 6.097 mg/mL) and the highest AEAC value (11.55  mg/g). For L-asparaginase production, the majority of the isolates (89.66%) showed positive results, especially among the culturable species of Fusarium, Trichoderma, and Daldinia. Most Fusarium spp. were able to produce L-asparaginase (80.77%), but the highest L-asparaginase activity was detected in Daldinia eschscholtzii (D14) with 2.128 units/mL. Results from this study highlighted the potential of endophytic fungi from medicinal orchids (Dendrobium sp.) as natural sources of bioactive compounds to be developed into novel antioxidants and anticancer drugs.

Mechanism of Dendrobium Nobile Polysaccharide Inhibition of Ferroptosis in Rats with Spinal Cord Injury.

BACKGROUND: It has been reported that ferroptosis participates in the pathophysiological mechanism of spinal cord injury (SCI). Our preliminary experiments verified that dendrobium nobile polysaccharide (DNP) improved the behavioral function of SCI rats. Therefore, the purpose of this study was to examine the role of DNP on ferroptosis and its neuroprotective mechanism in SCI rats. METHODS: Adult female sprague dawley (SD) rats were exposed to SCI by Allen's method, followed by an intragastric injection of 100 mg/kg DNP per day for 2 weeks. Behavioral features were verified by the Basso-Beattie-Bresnahan (BBB) scale and footprint evaluation. Iron content and glutathione (GSH) were assessed spectrophotometrically. Mitochondrial morphology was examined by transmission electron microscopy. The expression of ferroptosis-related genes, including System Xc- light chain (xCT), G-rich RNA sequence binding Factor 1 (GRSF1) and glutathione peroxidase 4 (Gpx4), was examined by real-time polymerase chain reaction (PCR) and western blot. The spinal cavity was defined using hematoxylin-eosin (HE) staining, and neuronal modifications were detected by immunofluorescence. RESULTS: Compared with the SCI group, the BBB score of rats in the DNP group increased at 7 d, 14 d, 21 d, and 28 d. The differences between the two groups were statistically significant. At 12 h post-injury the iron content began to decrease. At 24 h post-injury the iron content decreased significantly in the DNP group. The morphological changes of the mitochondrial crest and membrane in the DNP group were ameliorated within 24 h. Compared with the sham group, the expression of xCT, GSH, Gpx4, and GRSF1 were significantly reduced after SCI. After DNP treatment, the expression of xCT, Gpx4, and GSH were higher. The tissue cavity area was significantly reduced and the amount of NeuN+ cells was increased in the DNP group at 14 d and 28 d after SCI. CONCLUSIONS: DNP facilitated the post-injury recovery in SCI rats via the inhibition of ferroptosis.

Phytochemical Profile of Alkaloid Extract from Dendrobium huoshanense and Inhibitory Effects against Oxidative Stress in H2 O2 -Induced PC12 Cells.

This study aimed to explore the alkaloid profile of Dendrobium huoshanense and determine the potential protective effect against oxidative damage. The crude D. huoshanense alkaloid extract (DHAE) was obtained by 70 % ethanol extraction and liquid-liquid partition. DHAE contained specific alkaloid components with abundant 6-hydroxynobiline (58.15 %) and trace dendrobine (3.23 %) in the preliminary HPLC fingerprint and GC-MS analysis, which was distinguished from D. officinale or D. nobile. Subsequently, six alkaloids including 6-hydroxynobiline, 2-hydroxy dendrobine, nobilonine, dendrobine, Findlayines D and trans-dendrochrysanine were identified in the purified DHAE (namely DHSAE-3, DHSAE-3') via further solid phase extraction coupled with UPLC-MS/MS analysis. Meanwhile, pretreatment with DHAE or DHSAE (0.5, 5 µg/mL) increased cell viability by 14.0-57.4 % compared to that of H2 O2 -induced PC12 Model cells. Among them, 5 µg/mL DHSAE-3-treated cells displayed a pronounced reversion than the positive vitamin E (p<0.01). Furthermore, a clear cellular morphological restoration and 38.4 % reduction in intracellular reactive oxidative species level were achieved. Our findings suggest that D. huoshanense has a characteristic alkaloid profile represented by abundant 6-hydroxynobiline, and DHAEs exhibit obvious protection against oxidative neuronal damage. Overall, this study indicates that DHAEs might be used to inhibit oxidative stress and provide a source to develop novel neuroprotective drugs.

Bibenzyl-Phenylpropane Hybrids with Immunosuppressive Activities from Dendrobium Nobile Lindl.

Fifteen bibenyls and four fluorenones, including five new bibenzyl-phenylpropane hybrids, were isolated from the aerial part of Dendrobium nobile Lindl. Their structures were determined by spectroscopic methods. Bioassay on the LPS-induced proliferations of mouse splenic B lymphocytes, and Con A-induced T lymphocytes showed that compounds 1, 2, and 14 showed excellent immunosuppressive activities with IC50 values of 1.23, 1.01, and 3.87 µM, respectively, while compounds 3-4, 7, 10, 13, and 15 exhibited moderate immunosuppressive activities with IC50 values ranging from 6.89 to 14.2 µM.

Four Undescribed Stilbenoid Derivatives from the Aerial Parts of Dendrobium officinale with their α-Glucosidase and α-Amylase Inhibitory Activity.

In this study, four undescribed bibenzyl derivatives (1-4), together with seven known compounds (5-11) were isolated from the aerial parts of Dendrobium officinale. Their chemical structures were determined to be (7'S,8'S) -9''-acetyldendrocandin U (1), (7'S,8'S) -4'-methoxydendrocandin T (2), (7'R,8'S) -dendrocandin B (3), (1S,2R) -5'''-methoxydendrofindlaphenol C (4) by analyzing of the spectroscopic data including HR-ESI-MS, 1D-, and 2D-NMR spectra. The absolute configurations of compounds 1-4 were determined by the electronic circular dichroism (ECD) spectra. Compounds 1-3, 5, 10 and 11 inhibited α-glucosidase with the IC50 values ranging from 56.3 to 165.3 µM, compounds 1-3, 5, 7-10 inhibited α-amylase with the IC50 values ranging from 65.2 to 177.6 µM.

Dendrobium officinale polysaccharide alleviates thiacloprid-induced kidney injury in quails via activating the Nrf2/HO-1 pathway.

Thiacloprid (THI) is a neonicotinoid insecticide, and its wide-ranging use has contributed to severe environmental and health problems. Dendrobium officinale polysaccharide (DOP) possesses multiple biological activities such as antioxidant and antiapoptosis effect. Although present research has shown that THI causes kidney injury, the exact molecular mechanism and treatment of THI-induced kidney injury remain unclear. The study aimed to investigate if DOP could alleviate THI-induced kidney injury and identify the potential molecular mechanism in quails. In this study, Japanese quails received DOP (200 mg/kg) daily with or without THI (4 mg/kg) exposure for 42 days. Our results showed that DOP improved hematological changes, biochemical indexes, and nephric histopathological changes induced by THI. Meanwhile, THI exposure caused oxidative stress, apoptosis, and autophagy. Furthermore, THI and DOP cotreatment significantly activated the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) pathway, restored antioxidant enzyme activity, and reduced apoptosis and autophagy in quail kidneys. In summary, our study demonstrated that DOP mitigated THI-mediated kidney injury was associated with oxidative stress, apoptosis, and autophagy via activation of the Nrf2/HO-1 signaling pathway in quails.

First Report of Brown Leaf Rot Disease on Dendrobium nobile Caused by Xylaria flabelliformis in Guizhou Province, China.

Dendrobium nobile is the largest species of the Orchidaceae family and produces dendrobine, a compound with medicinal properties (Sarsaiya et al., 2020a; Sarsaiya et al., 2024; Qian et al., 2024). The accumulation of dendrobine in D. nobile is regulated by various pathogenic fungi, which directly and indirectly influence dendrobine biosynthesis (Sarsaiya et al., 2019a; Sarsaiya et al., 2019b). In a field planted with D. nobile in Guizhou Province, China, small lesions were initially observed on the upper part of the leaves from May to June 2019, which later developed into larger brown necrotic leaf lesions. Over time, these lesions greatly impacted the medicinal value (dendrobine) and productivity of the plant. A pure culture of Xylaria flabelliformis from infected wild D. nobile leaves was recovered and subsequently cultured on potato dextrose agar (PDA) at 25 °C for 5 days. Xylaria flabelliformis grew slowly and was composed of white mycelia. Colonies were initially white, with a regular margin, and formed stromata that consisted of mycelia sterilia without ascospores. We identified the strain as Xylaria flabelliformis based on its morphological characteristics (Liu et al., 2007) and by sequencing elongation factor-1α (EF-1α). The length of the DNA sequence of EF-1α that was used for the analysis of Xylaria flabelliformis was 1188 bp. BLASTx (nucleotide 6-frame translation-protein) analysis using the National Center for Biotechnology Information database showed that the obtained protein sequence (BLASTx protein accession no.: UTS95822.1, BLASTn nucleotide sequence accession no.: MW508334.1) had the highest similarity (98.21%) with the X. flabelliformis hypothetical protein (TRX95197.1) based on a thorough phylogenetic comparison with other Xylaria species. Healthy D. nobile seedlings were planted in pots and sterilized. The terminal leaves were excised from all pre-sterilised D. nobile seedlings and inoculated with Xylaria flabelliformis mycelial plugs, whereas sterile PDA plugs and moist cotton plugs were used as controls. All seedlings were maintained under optimum temperature and humidity conditions (25 °C and 80%, respectively) for seven days for observation and analysis. All experiments were performed in triplicate. After the incubation period, brown leaf rot lesions were observed for the first time on the inoculated D. nobile leaves, but no symptoms were observed on the leaves of the two control groups (sterile PDA plugs and moist cotton plugs). To complete Koch's postulates, Xylaria flabelliformis was re-isolated and identified from all diseased tissues by DNA sequencing of the EF-1α. It was determined for the first time that Xylaria flabelliformis can cause brown leaf lesions in D. nobile. Moreover, the pathogenicity of Xylaria flabelliformis in D. nobile has not been previously reported (Mead et al., 2019; Meng et al., 2019; Sarsaiya et al., 2019a; Sarsaiya et al., 2020b; Chen et al., 2023; Rinchen, 2023; Cao et al., 2024). To the best of our knowledge, this is the first report of BLRS lesions in D. nobile leaves caused by Xylaria flabelliformis in Guizhou Province, China. Identification of Xylaria flabelliformis as a pathogen of D. nobile is crucial for advancing effective management and control practices against brown leaf rot disease. This discovery provides valuable insights into the development of targeted strategies to mitigate the impact of Xylaria flabelliformis on D. nobile, safeguard medicinal properties such as dendrobine, and enhance overall productivity.

Dendrobium officinale polysaccharides-chemical properties and pharmacodynamic effects on the airways in experimental conditions.

The study aimed to analyze the effects of Dendrobium polysaccharides on the cough and airway reactivity and compare them with the effects of clinically used antitussives (codeine phosphate and butamirate citrate) and bronchodilators (salbutamol), using the guinea pig test system. Dendrobium officinale polysaccharides contained proteins (4.0 wt%) and phenolic compounds (1.7 wt%) with a molecular weight of 25,000 g/mol. The sugar analysis revealed a dominance of glucose (93.7 wt%) and a lesser amount of mannose (5.1 wt%) while other sugar quantities were negligible. Methylation analysis indicated the presence of highly branched polysaccharides. Glucose was found mainly as terminal, 1,4- and 1,6-linked. Furthermore, some 1,4- and 1,6-linked glucose units were found branched at O2, O3, and O6/O4. Mannose was terminal and 1,4-linked. NMR spectra signals indicate the presence of the (1→4)-linked α-d-glucan, (1→4)-linked ß-d-glucan branched at position O6, (1→6)-linked ß-d-glucan branched at position O3 and (1→4)-linked glucomannan. Pharmacological studies showed statistically significant antitussive activity of Dendrobium polysaccharides, exceeding the effect of clinically used antitussives, which may be partially associated with confirmed bronchodilation and the ability of polysaccharides to increase the threshold of cough receptor activation. Dendrobium polysaccharides may increase the possibility of symptomatic treatment of cough, especially in asthmatics.

Quantitative analysis of six sesquiterpene glycosides from Dendrobium nobile Lindl. under different growth conditions by high-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry in MRM mode.

INTRODUCTION: The sesquiterpene glycosides (SGs) from Dendrobium nobile Lindl. have immunomodulatory effects. However, there are no studies on the growth conditions affecting its contents and quantitative analysis methods. OBJECTIVE: In the present study, a quantitative analysis method for six SGs from D. nobile was established. We explored which growth conditions could affect the contents of SGs, providing a basis for the cultivation and clinical application of D. nobile. METHODS: Firstly, based on the optimization of mass spectrometry parameters and extraction conditions for six SGs in D. nobile, a method for the determination of the contents of six SGs was established using high-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (HPLC-QqQ-MS/MS) in multiple reaction monitoring (MRM) mode. Then, the methodology of the established method was validated. Secondly, the established method was applied to determine the contents of six SGs from 78 samples of D. nobile grown under different growth conditions. Finally, chemometrics analysis was employed to analyze the results and select optimal growth conditions for D. nobile. RESULTS: The results indicated significant variations in the contents of SGs from D. nobile grown under different growth conditions. The primary factors influencing SG contents included age, geographical origin, altitude, and epiphytic pattern. CONCLUSION: Therefore, the established method for determining SG contents from D. nobile is stable. In particular, the SG contents were relatively high in samples of 3-year-old D. nobile grown at an altitude of approximately 500 m on Danxia rocks in Chishui, Guizhou.

A new phenanthrene with a spirolactone ring from Dendrobium ochreatum.

Dendroochreatene (1), a new phenanthrene derivative with a spirolactone ring, was isolated from the whole Dendrobium ochreatum plant together with 11 known compounds (2-12). The structure of the new compound was elucidated spectroscopically and phenolic compounds were firstly reported from D. ochreatum. Moscatilin (4), major compound isolated from D. ochreatum, was found to be cytotoxic toward H460 lung-cancer cells, with an IC50 value of 147.3 ± 0.9 µM, while loddigesiinol C (7), C-α-methoxy derivative was inactive.

Drought Stress Induced Different Response Mechanisms in Three Dendrobium Species under Different Photosynthetic Pathways.

Many Dendrobium species, which hold a high status and value in traditional Chinese medicine, grow on barks and rocks in the wild, often encountering harsh environments and facing droughts. However, the molecular mechanisms underlying the shift in the photosynthetic pathway induced by drought remain unclear. To address this issue, three Dendrobium species with different photosynthetic pathways were selected for sequencing and transcriptome data analysis after drought treatment. The findings included 134.43 GB of sequencing data, with numerous Differentially Expressed Genes (DEGs) exhibiting different response mechanisms under drought stress. Gene Ontology (GO)-KEGG-based enrichment analysis of DEGs revealed that metabolic pathways contributed to drought tolerance and alterations in photosynthetic pathways. Phosphoenolpyruvate Carboxylase (PEPC) was subjected to phylogenetic tree construction, sequence alignment, and domain analysis. Under drought stress, variations were observed in the PEPC gene structure and expression among different Dendrobium species; the upregulation of Dc_gene2609 expression may be caused by dof-miR-384, which resulted in the shift from C3 photosynthesis to CAM, thereby improving drought tolerance in Dendrobium. This study revealed the expression patterns and roles of PEPC genes in enhancing plant drought tolerance and will provide an important basis for in-depth research on Dendrobium's adaptation mechanisms in arid environments.