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Background: Dendrobium catenatum is a perennial herb of the genus Dendrobium orchidaceae. It has been known as "Golden Grass, Soft Gold" since ancient times with effects of strengthening the body, benefiting the stomach, generating body fluid, nourishing Yin and clearing internal heat. The flowers of D. catenatum have anti-oxidation, immune regulation and other biological activities. The composition analysis of flowers showed that flavonoid glycosides were significantly accumulated in floral tissue. However, in the flowers of D. catenatum, there was only one case of the UDP-glycosyltransferase (UGT) responsible for the glycosylation of flavonoids has been reported., Result: In this study, a new UGT (named UGT708S6) was cloned from D. catenatum flowers rich in O-glycosides and C-glycosides, and its function and biochemical properties were characterized. Through homology comparison and molecular docking, we identified the key amino acid residues affecting the catalytic function of UGT708S6. The glycosyltransferase UGT708S6 was characterized and demonstrated C-glycosyltransferase (CGT) activity in vitro assay using phloretin and 2-hydroxynaringenin as sugar acceptors. The catalytic promiscuity assay revealed that UGT708S6 has a clear sugar donor preference, and displayed O-glycosyltransferase (OGT) activity towards luteolin, naringenin and liquiritigenin. Furthermore, the catalytic characteristics of UGT708S6 were explored, shedding light on the structural basis of substrate promiscuity and the catalytic mechanism involved in the formation of flavonoid C-glycosides. R271 was a key amino acid residue site that sustained the catalytic reaction. The smaller binding pocket resulted in the production of new O-glycosides and the reduction of C-glycosides. This highlighted the importance of the binding pocket in determining whether C-glycosides or O-glycosides were produced., Conclusions: The findings suggest that UGT708S6 holds promise as a new glycosyltransferase for synthesizing flavonoid glycosides and offer valuable insights for further understanding the catalytic mechanisms of flavonoid glycosyltransferases., Competing Interests: Declarations Ethics approval and consent to participate Not applicable. Consent for publication Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Aluminum-activated malate transporter ( ALMT ) genes play an important role in aluminum ion (Al 3+ ) tolerance, fruit acidity, and stomatal movement. Although decades of research have been carried out in many plants, there is little knowledge about the roles of ALMT in Orchidaceae. In this study, 34 ALMT genes were identified in the genomes of four orchid species. Specifically, ten ALMT genes were found in Dendrobium chrysotoxum and D. catenatum , and seven were found in Apostasia shenzhenica and Phalaenopsis equestris . These ALMT genes were further categorized into four clades (clades 1-4) based on phylogenetic relationships. Sequence alignment and conserved motif analysis revealed that most orchid ALMT proteins contain conserved regions (TM1, GABA binding motif, and WEP motif). We also discovered a unique motif (19) belonging to clade 1, which can serve as a specifically identified characteristic. Comparison with the gene structure of AtALMT genes ( Arabidopsis thaliana ) showed that the gene structure of ALMT was conserved across species, but the introns were longer in orchids. The promoters of orchid ALMT genes contain many light-responsive and hormone-responsive elements, suggesting that their expression may be regulated by light and phytohormones. Chromosomal localization and collinear analysis of D. chrysotoxum indicated that tandem duplication (TD) is the main reason for the difference in the number of ALMT genes in these orchids. D. catenatum was chosen for the RT-qPCR experiment, and the results showed that the DcaALMT gene expression pattern varied in different tissues. The expression of DcaALMT1-9 was significantly changed after ABA treatment. Combining the circadian CO 2 uptake rate, titratable total acid, and RT-qPCR data analysis, most DcaALMT genes were highly expressed at night and around dawn. The result revealed that DcaALMT genes might be involved in photosynthate accumulation. The above study provides more comprehensive information for the ALMT gene family in Orchidaceae and a basis for subsequent functional analysis.

Background: Dendrobium officinale Kimura et Migo (D. officinale) is parasitic on rocks or plants with very few mineral elements that can be absorbed directly, so its growth and development are affected by nutritional deficiencies. Previous studies found that phosphorus deficiency promotes polysaccharides accumulation in D. officinale, the expression of DoCSLA6 (glucomannan synthase gene) was positively correlated with polysaccharide synthesis. However, the molecular mechanism by which the low phosphorus environment affects polysaccharide accumulation remains unclear., Results: We found that DoSPX1 can reduce phosphate accumulation in plants and promote the expression of PSIs genes, thereby enhancing plant tolerance to low phosphorus environments.Y1H and EMSA experimental show that DoMYB37 can bind the promoter of DoCSLA6. DoSPX1 interact with DoMYB37 transiently overexpressed DoSPX1 and DoMYB37 in D. officinale protocorm-like bodies, decreased the Pi content, while increased the expression of DoCSLA6., Conclusions: The signaling pathway of DoSPX1-DoMYB37-DoCSLA6 was revealed. This provides a theoretical basis for the accumulation of polysaccharide content in D. officinale under phosphorus starvation., (© 2024. The Author(s).)

Background: Unfavorable temperatures significantly constrain the quality formation of Dendrobium officinale, severely limiting its food demand. Salicylic acid (SA) enhances the resistance of D. officinale to stress and possesses various analogs. The impact and mechanism of the SA family on improving the quality of D. officinale under adverse temperature conditions remains unclear., Results: Combined with molecular docking analysis, chlorophyll fluorescence and metabolic analysis after treatments with SA analogues or extreme temperatures are performed in this study. The results demonstrate that both heat and cold treatments impede several main parameters of chlorophyll fluorescence of D. officinale, including the ΦPSII parameter, a sensitive growth indicator. However, this inhibition is mitigated by SA or its chemically similar compounds. Comprehensive branch imaging of ΦPSII values revealed position-dependent improvement of tolerance. Molecular docking analysis using a crystal structure model of NPR4 protein reveals that the therapeutic effects of SA analogs are determined by their binding energy and the contact of certain residues. Metabolome analysis identifies 17 compounds are considered participating in the temperature-related SA signaling pathway. Moreover, several natural SA analogs such as 2-hydroxycinnamic acid, benzamide, 2-(formylamino) benzoic acid and 3-o-methylgallic acid, are further found to have high binding ability to NPR4 protein and probably enhance the tolerance of D. officinale against unfavorable temperatures through flavone and guanosine monophosphate degradation pathways., Conclusions: These results reveal that the SA family with a high binding capability of NPR4 could improve the tolerance of D. officinale upon extreme temperature challenges. This study also highlights the collaborative role of SA-related natural compounds present in D. officinale in the mechanism of temperature resistance and offers a potential way to develop protective agents for the cultivation of D. officinale., (© 2024. The Author(s).)

Dendrobium species, which are perennial herbs widely distributed in tropical and subtropical regions, are notable for their therapeutic properties attributed to various bioactive compounds, including dendrobine-type sesquiterpenoid alkaloids (DTSAs). The objective of this review article is to provide a comprehensive overview of recent advances in the biosynthesis of DTSAs, including their extraction from Dendrobium species and endophytes, elucidation of associated genes through genomic and transcriptomic sequencing in both Dendrobium spp. and endophytes, exploration of the biosynthetic pathways of DTSAs, and drawing conclusions and outlining future perspectives in this field. Alkaloids, predominantly nitrogen-containing compounds found in medicinal orchids, include over 140 types discovered across more than 50 species. DTSAs, identified in 37 picrotoxane alkaloids, have a distinctive five-membered nitrogen heterocyclic ring. This review highlights endophytic fungi as alternative sources of DTSAs, emphasizing their potential in pharmaceutical applications when plant-derived compounds are scarce or complex. Genomic and transcriptomic sequencing of Dendrobium spp. and their endophytes has identified key genes involved in DTSAs biosynthesis, elucidating pathways such as the mevalonate (MVA) and 2-C-methyl-D-erythritol 4-phosphate (MEP) pathways. Genes encoding enzymes, such as acetyl-CoA C-acetyltransferase and diphosphomevalonate decarboxylase, are positively associated with dendrobine production. Despite significant advancements, the complexity of terpenoid biosynthesis in different subcellular compartments remains a challenge. Future research should focus on leveraging high-quality genomic data and omics technologies to further understand and manipulate the biosynthetic pathways of DTSAs and enhance their medicinal use.

Lead affects photosynthesis and growth and has serious toxic effects on plants. Here, the differential expressed proteins (DEPs) in D. huoshanense were investigated under different applications of lead acetate solutions. Using label-free quantitative proteomics methods, more than 12,000 peptides and 2,449 proteins were identified. GO and KEGG functional annotations show that these differential proteins mainly participate in carbohydrate metabolism, energy metabolism, amino acid metabolism, translation, protein folding, sorting, and degradation, as well as oxidation and reduction processes. A total of 636 DEPs were identified, and lead could induce the expression of most proteins. KEGG enrichment analysis suggested that proteins involved in processes such as homologous recombination, vitamin B6 metabolism, flavonoid biosynthesis, cellular component organisation or biogenesis, and biological regulation were significantly enriched. Nearly 40 proteins are involved in DNA replication and repair, RNA synthesis, transport, and splicing. The effect of lead stress on D. huoshanense may be achieved through photosynthesis, oxidative phosphorylation, and the production of excess antioxidant substances. The expression of 9 photosynthesis-related proteins and 12 oxidative phosphorylation-related proteins was up-regulated after lead stress. Furthermore, a total of 3 SOD, 12 POD, 3 CAT, and 7 ascorbate-related metabolic enzymes were identified. Under lead stress, almost all key enzymes involved in the synthesis of antioxidant substances are up-regulated, which may facilitate the scavenging of oxygen-free radical scavenging. The expression levels of some key enzymes involved in sugar and glycoside synthesis, the phenylpropanoid synthesis pathway, and the terpene synthesis pathway also increased. More than 30 proteins involved in heavy metal transport were also identified. Expression profiling revealed a significant rise in the expression of the ABC-type multidrug resistance transporter, copper chaperone, and P-type ATPase with exposure to lead stress. Our findings lay the basis for research on the response and resistance of D. huoshanense to heavy metal stress., (© 2024. The Author(s).)

Dendrobium sinense , an endemic medicinal herb in Hainan Island, is rich in bibenzyl compounds. However, few studies have explored the molecular mechanisms of bibenzyl biosynthesis. This study presents a comprehensive analysis of DsBBS1 and DsBBS2 function in D. sinense . A molecular docking simulation revealed high-resolution three-dimensional structural models with minor domain orientation differences. Expression analyses of DsBBS1 and DsBBS2 across various tissues indicated a consistent pattern, with the highest expression being found in the roots, implying that they play a pivotal role in bibenzyl biosynthesis. Protein expression studies identified optimal conditions for DsBBS2-HisTag expression and purification, resulting in a soluble protein with a molecular weight of approximately 45 kDa. Enzyme activity assays confirmed DsBBS2's capacity to synthesize resveratrol, exhibiting higher V max and lower K m values than DsBBS1. Functional analyses in transgenic Arabidopsis demonstrated that both DsBBS1 and DsBBS2 could complement the Atchs mutant phenotype. The total flavonoid content in the DsBBS1 and DsBBS2 transgenic lines was restored to wild-type levels, while the total bibenzyl content increased. DsBBS1 and DsBBS2 are capable of catalyzing both bibenzyl and flavonoid biosynthesis in Arabidopsis . This study provides valuable insights into the molecular mechanisms underlying the biosynthesis of bibenzyl compounds in D. sinense .

Glutathione S-transferases (GSTs) are members of a protein superfamily with diverse physiological functions, including cellular detoxification and protection against oxidative damage. However, there is limited research on GSTs responding to cadmium (Cd) stress. This study classified 46 GST genes in Dendrobium officinale ( D. officinale ) into nine groups using model construction and domain annotation. Evolutionary analysis revealed nine subfamilies with diverse physical and chemical properties. Prediction of subcellular localization revealed that half of the GST members were located in the cytoplasm. According to the expression analysis of GST family genes responding to Cd stress, DoGST5 responded significantly to Cd stress. Transient expression of DoGST5-GFP in tobacco leaves revealed that DoGST5 was localized in the cytoplasm. DoGST5 overexpression in Arabidopsis enhanced Cd tolerance by reducing Cd-induced H 2 O 2 and O 2 - levels. These findings demonstrate that DoGST5 plays a critical role in enhancing Cd tolerance by balancing reactive oxygen species (ROS) levels, offering potential applications for improving plant adaptability to heavy metal stress.

Dendrobium nobile is an important orchid plant that has been used as a traditional herb for many years. For the further pharmaceutical development of this resource, a combined transcriptome and metabolome analysis was performed in different parts of D. nobile . First, saccharides, organic acids, amino acids and their derivatives, and alkaloids were the main substances identified in D. nobile . Amino acids and their derivatives and flavonoids accumulated strongly in flowers; saccharides and phenols accumulated strongly in flowers and fruits; alkaloids accumulated strongly in leaves and flowers; and a nucleotide and its derivatives and organic acids accumulated strongly in leaves, flowers, and fruits. Simultaneously, genes for lipid metabolism, terpenoid biosynthesis, and alkaloid biosynthesis were highly expressed in the flowers; genes for phenylpropanoids biosynthesis and flavonoid biosynthesis were highly expressed in the roots; and genes for other metabolisms were highly expressed in the leaves. Furthermore, different members of metabolic enzyme families like cytochrome P450 and 4-coumarate-coA ligase showed differential effects on tissue-specific metabolic accumulation. Members of transcription factor families like AP2-EREBP, bHLH, NAC, MADS, and MYB participated widely in differential accumulation. ATP-binding cassette transporters and some other transporters also showed positive effects on tissue-specific metabolic accumulation. These results systematically elucidated the molecular mechanism of differential accumulation in different parts of D. nobile and enriched the library of specialized metabolic products and promising candidate genes.

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., (© 2024. The Author(s).)

Objectives: Pb stress has a negative impact on plant growth by interfering with photosynthesis and releasing reactive oxygen species, causing major risks such as heavy metal ion accumulation in the soil matrix. A proteomics experiment was conducted to determine whether protein levels of Dendrobium huoshanense changed in response to Pb stress seven to fifteen days after being sprayed with a 200 mg/L Pb (NO 3 ) 2 solution. The proteomic data we gathered provides a model for investigations into the mechanisms underlying Dendrobium plant resistance to heavy metal stress., Data Description: A label-free quantitative proteomics approach was employed to examine the variations in protein expression levels of D. huoshanense at different times of Pb(NO 3 ) 2 treatment. We submitted the raw data obtained from these proteomics sequencing experiments to the ProteomeXchange database with the accession number PXD047050. 63,194 mass spectra in total were compared after being imported into the Proteome Discoverer software for database search. A total of 12,402 spectral peptides were identified with a confidence level exceeding 99%, which resulted in the identification of 2,449 significantly differential proteins. These proteins can be utilized for screening, functional annotation, and enrichment analysis of differentially expressed proteins before and after heavy metal treatment experiments., (© 2024. The Author(s).)

Background: Dendrobium , with profound botanical importance, reveals a rich composition of bioactive compounds, including polysaccharides, flavonoids, alkaloids, and diverse amino acids, holding promise for skin regeneration. However, the precise mechanism remains elusive. Seeking a potent natural remedy for wound healing, exocyst vesicles were successfully isolated from Dendrobium ., Aims of the Study: This investigation aimed to employ bioinformatics and in vivo experiments to elucidate target genes of Dendrobium -derived nanovesicles in skin wound healing, focusing on immune infiltration and senescence characteristics., Materials and Methods: C57 mice experienced facilitated wound healing through Dendrobium -derived nanovesicles (DDNVs). Bioinformatics analysis and GEO database mining identified crucial genes by intersecting immune-related, senescence-related, and PANoptosis-associated genes. The identified genes underwent in vivo validation., Results: DDNVs remarkably accelerated skin wound healing in C57 mice. Bioinformatics analysis revealed abnormal expression patterns of immune-related, senescence-related, and pan-apoptosis-related genes, highlighting an overexpressed IL-1β and downregulated IL-18 in the model group, Exploration of signaling pathways included IL-17, NF-kappa B, NOD-like receptor, and Toll-like receptor pathways. In vivo experiments confirmed DDNVs' efficacy in suppressing IL-1β expression, enhancing wound healing., Conclusion: Plant-derived nanovesicles (PDNV) emerged as a natural, reliable, and productive approach to wound healing. DDNVs uptake by mouse skin tissues, labeled with a fluorescent dye, led to enhanced wound healing in C57 mice. Notably, IL-1β overexpression in immune cells and genes played a key role. DDNVs intervention effectively suppressed IL-1β expression, accelerating skin wound tissue repair., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 Tu et al.)

Dendrobium nobile is a traditional Chinese herb with anti-inflammatory, antioxidant, and neuroprotective properties. However, its antiaging effects are unclear. Herein, we studied the aging-related functions and the mechanism of action of the alcohol extract of Dendrobium nobile (DnAE) in the model organism Caenorhabditis elegans . The results indicated that 1 mg/mL DnAE slowed lipofuscin accumulation, decreased the levels of reactive oxygen species, elevated superoxide dismutase activity, enhanced oxidative and heat stress resistance, extended the lifespan of nematodes, protected their dopamine neurons from 6-hydroxydopamine-induced neurodegeneration, and reduced Aβ-induced neurotoxicity. DnAE upregulated the mRNA expression of the transcription factors DAF-16 and HSF-1, promoted the nuclear localization of DAF-16, and enhanced the fluorescence intensity of HSP-16.2. However, it had no effect on the lifespan of DAF-16 mutants. Thus, DnAE can significantly extend lifespan, enhance heat stress tolerance, and delay age-related diseases through a DAF-16-dependent pathway.

Background: R2R3-MYB genes comprise one of the largest and most important gene families in plants, and are involved in the regulation of plant growth and development as well as responses to abiotic stresses. However, the functions of R2R3-MYB genes in Dendrobium nobile remains largely unknown., Methods: Here, a comprehensive genome-wide analysis of D. nobile R2R3-MYB genes was performed, in which phylogenic relationships, gene structures, motif composition, chromosomal locations, collinearity analysis, and cis -acting elements were investigated. Moreover, the expression patterns of selected DnMYB genes were analyzed in various tissues and under different abiotic stresses., Results: In total, 125 DnMYB genes were identified in the D. nobile genome, and were subdivided into 26 groups based on phylogenetic analysis. Most genes in the same subgroup showed similar exon/intron structure and motif composition. All the DnMYB genes were mapped to 19 chromosomes with the co-linearity relationship. Reverse transcription-quantitative real-time PCR (RT-qPCR) results showed that 8 DnMYBs exhibited different expression patterns in different plant tissues, and were differentially expressed in response to abscisic acid, methyl jasmonate, low-temperature stress., Conclusions: This work contributes to a comprehensive understanding of the R2R3-MYB gene family in D. nobile , and provides candidate genes for future research on abiotic stress in this plant., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s). Published by IMR Press.)

The PEBP gene family plays a significant role in regulating flower development and formation. To understand its function in Dendrobium chrysotoxum and D. nobile flowering, we identified 22 PEBP genes (11 DchPEBP s and 11 DnoPEBP s) from both species. We conducted analyses on their conserved domains and motifs, phylogenetic relationships, chromosome distribution, collinear correlation, and cis elements. The classification results showed that the 22 PEBP s were mainly divided into three clades, as follows: FT, MFT, and TFL1. A sequence analysis showed that most PEBP proteins contained five conserved domains, while a gene structure analysis revealed that 77% of the total PEBP genes contained four exons and three introns. The promoter regions of the 22 PEBP s contained several cis elements related to hormone induction and light response. This suggests these PEBP s could play a role in regulating flower development by controlling photoperiod and hormone levels. Additionally, a collinearity analysis revealed three pairs of duplicate genes in the genomes of both D. chrysotoxum and D. nobile . Furthermore, RT-qPCR has found to influence the regulatory effect of DchPEBP s on the development of flower organs (sepals, petals, lip, ovary, and gynostemium) during the flowering process (bud, transparent stage, and initial bloom). The results obtained imply that DchPEBP8 and DchPEBP9 play a role in the initial bloom and that DchPEBP7 may inhibit flowering processes. Moreover, DchPEBP9 may potentially be involved in the development of reproductive functionality. PEBP s have regulatory functions that modulate flowering. FT initiates plant flowering by mediating photoperiod and temperature signals, while TFL1 inhibits flowering processes. These findings provide clues for future studies on flower development in Dendrobium.

Dendrobium Sw. (family Orchidaceae) is a renowned edible and medicinal plant in China. Although widely cultivated and used, less research has been conducted on differential Dendrobium species. In this study, stems from seven distinct Dendrobium species were subjected to UPLC-QTOF-MS/MS analysis. A total of 242 metabolites were annotated, and multivariate statistical analysis was employed to explore the variance in the extracted metabolites across the various groups. The analysis demonstrated that D. nobile displays conspicuous differences from other species of Dendrobium . Specifically, D. nobile stands out from the remaining six taxa of Dendrobium based on 170 distinct metabolites, mainly terpene and flavonoid components, associated with cysteine and methionine metabolism, flavonoid biosynthesis, and galactose metabolism. It is believed that the variations between D. nobile and other Dendrobium species are mainly attributed to three metabolite synthesis pathways. By comparing the chemical composition of seven species of Dendrobium , this study identified the qualitative components of each species. D. nobile was found to differ significantly from other species, with higher levels of terpenoids, flavonoids, and other compounds that are for the cardiovascular field. By comparing the chemical composition of seven species of Dendrobium , these qualitative components have relevance for establishing quality standards for Dendrobium .

Dendrobium nobile Lindl., as an endangered medicinal plant within the genus Dendrobium , is widely distributed in southwestern China and has important ecological and economic value. There are a variety of metabolites with pharmacological activity in D. nobile . The alkaloids and polysaccharides contained within D. nobile are very important active components, which mainly have antiviral, anti-tumor, and immunity improvement effects. However, the changes in the compounds and functional genes of D. nobile induced by methyl jasmonate (MeJA) are not clearly understood. In this study, the metabolome and transcriptome of D. nobile were analyzed after exposure to MeJA. A total of 377 differential metabolites were obtained through data analysis, of which 15 were related to polysaccharide pathways and 35 were related to terpenoids and alkaloids pathways. Additionally, the transcriptome sequencing results identified 3256 differentially expressed genes that were discovered in 11 groups. Compared with the control group, 1346 unigenes were differentially expressed in the samples treated with MeJA for 14 days (TF14). Moreover, the expression levels of differentially expressed genes were also significant at different growth and development stages. According to GO and KEGG annotations, 189 and 99 candidate genes were identified as being involved in terpenoid biosynthesis and polysaccharide biosynthesis, respectively. In addition, the co-expression analysis indicated that 238 and 313 transcription factors (TFs) may contribute to the regulation of terpenoid and polysaccharide biosynthesis, respectively. Through a heat map analysis, fourteen terpenoid synthetase genes, twenty-three cytochrome P450 oxidase genes, eight methyltransferase genes, and six aminotransferase genes were identified that may be related to dendrobine biosynthesis. Among them, one sesquiterpene synthase gene was found to be highly expressed after the treatment with MeJA and was positively correlated with the content of dendrobine. This study provides important and valuable metabolomics and transcriptomic information for the further understanding of D. nobile at the metabolic and molecular levels and provides candidate genes and possible intermediate compounds for the dendrobine biosynthesis pathway, which lays a certain foundation for further research on and application of Dendrobium .

Natural products are irreplaceable reservoirs for cancer treatments. In this study, 12 phenanthrene compounds were extracted and isolated from Dendrobium officinale . Each chemical structure was identified using comprehensive NMR analysis. All compounds were evaluated for their cytotoxic activities against five tumor cell lines, i.e., HeLa, MCF-7, SK-N-AS, Capan-2 and Hep G2. Compound 5, 1,5,6-trimethoxy-2,7-dihydroxyphenanthrene, displayed the most significant cytotoxic effect against HeLa and Hep G2 cells, with an IC 50 of 0.42 and 0.20 μM. For Hela cells, further experiments demonstrated that compound 5 could obviously inhibit cell migration, block cell cycle in the G0/G1 phase and induce apoptosis. Expression measurements for p53 indicated that knock down of p53 by siRNA could mitigate the apoptosis induced by compound 5. Therefore, the compound 5 is a potential candidate drug for HeLa cells in cervical cancer.

Dendrobium officinale polysaccharide (DOP) has shown various biological activities. However, the ability of DOP to participate in immune regulation during anti-gastric cancer treatment has remained unclear. In this study, the in vitro results showed that DOP has the potential to polarize THP-1 macrophages from the M2 to the M1 phenotype, downregulate the STAT6/PPAR-r signaling pathway and the protein expression of their down-targeted ARG1 and TGM2, and further decrease the main protein and mRNA expression in the JAGGED1/NOTCH1 signaling pathway. DOP suppressed the migration of gastric cancer cells by decreasing the protein expression of N-cadherin and Vimentin and increasing E-cadherin. In addition, CM-DOP promoted the apoptosis of gastric cancer cells by upregulating Caspase-3 and increasing the ratio of Bax/Bcl-2. In vivo, DOP effectively inhibited the growth of tumors and the expression of Ki-67. In summary, these findings demonstrated that DOP converted the polarization of M2 subtype macrophages into M1 subtypes via the STAT6/PPAR-r and JAGGED1/NOTCH1 signaling pathways in order to reduce apoptosis and prevent migration, thus indicating the potential of DOP as an adjuvant tumor therapy in preclinical and clinical trials.

Backgrounds: High glucose (HG) caused oxidative stress and mitochondrial dysfunction, resulting in insulin resistance in podocytes, a key mechanism of diabetic nephropathy. Dendrobium officinale polysaccharide (DOP) was able to improve insulin resistance and antioxidant capability., Objective: The purpose of this study is to explore the mechanism by which DOP decreases the podocyte injury induced by HG., Methods: MPC5 cells were treated with HG, DOP, and IRS-1/2 inhibitor NT157. Afterwards, glucose consumption, generations of ROS and MDA were measured using the detection kits. Mitophagy was monitored using both MtphagTracyker and LysoTracker. The mitochondrial membrane potential was evaluated by JC-1 staining. DOP was also used in a mouse model of diabetes, with the measurements of urine albumin, blood creatinine and blood urea nitrogen., Results: Treatment with DOP suppressed the HG-induced reduction of glucose consumption, the phosphorylation of IRS-1 (phospho Y632), AKT (phospho Ser473 and Thr308) and Nephrin. In addition, HG-induced augment of ROS and MDA, formation of γ-H2A.X foci and translocation of AKT to nucleus were inhibited by DOP. DOP enhanced mitophagy, which was associated with decreased mitochondrial membrane potential and ROS production. DOP conferred protective effect on podocyte in the diabetic mouse by reducing the albumin/creatinine ratio and blood urea nitrogen, and restoring Nephrin expression in podocytes., Conclusions: DOP alleviates HG-induced podocyte injuryby regulating IRS-1/AKT signal and promoting mitophagy.

The TCP gene family are plant-specific transcription factors that play important roles in plant growth and development. Dendrobium chrysotoxum , D. nobile , and D. huoshanense are orchids with a high ornamental value, but few studies have investigated the specific functions of TCP s in Dendrobium flower development. In this study, we used these three Dendrobium species to analyze TCP s, examining their physicochemical properties, phylogenetic relationships, gene structures, and expression profiles. A total of 50 TCP s were identified across three Dendrobium species; they were divided into two clades-Class-I (PCF subfamily) and Class-II (CIN and CYC/TB1 subfamilies)-based on their phylogenetic relationships. Our sequence logo analysis showed that almost all Dendrobium TCP s contain a conserved TCP domain, as well as the existence of fewer exons, and the cis -regulatory elements of the TCP s were mostly related to light response. In addition, our transcriptomic data and qRT-PCR results showed that DchTCP2 and DchTCP13 had a significant impact on lateral organs. Moreover, changes in the expression level of DchTCP4 suggested its important role in the phenotypic variation of floral organs. Therefore, this study provides a significant reference for the further exploration of TCP gene functions in the regulation of different floral organs in Dendrobium orchids.

A weak codon usage bias was found in Dendrobium catenatum (D. officiale) antimicrobial peptides (AMPs), after the analysis of relative synonymous codon usage, GC contents, and the effective number of codons. The codon usage preference was mainly influenced by natural selection pressure. The self-optimized prediction method and SWISS-MODEL were applied for peptide structural and domain analyses, and some typical antimicrobial domains were found in D. officinale AMP amino sequences, such as knot1 domain, gibberellins-stimulated domain, cupin_1 domain, defensin_like domain, and SLR1-BP (S locus-related glycoprotein 1 binding pollen coat protein) domain. To investigate the AMPs gene expression pattern, abiotic stresses, such as salt stress, drought stress, salicylic acid (SA), and methyl jasmonate (JA), were applied and the gene expression levels were detected by the real-time fluorescent quantitative polymerase chain reaction. Results showed that, even though the basic AMPs gene expressions were low, some AMPs can still be induced by salt dress, while the drought dress did not show the same impact. The SA and JA signaling pathways might be involved in most of the AMPs expressions. The natural selection of the D. officinale AMPs and thus forming diverse types of AMPs enhanced the plant's innate immunity and disease resistance capability, which would lead to a better understanding of the molecular mechanism for D. officinale adapting to the environment. The finding that salt stress, SA, and JA signaling pathways can induce AMP expression lays a foundation for the further development and functional verification of D. officinale AMPs., (© 2023 The Authors. The Plant Genome published by Wiley Periodicals LLC on behalf of Crop Science Society of America.)

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., (© 2023 Society for Experimental Biology and John Wiley & Sons Ltd.)

Background: Dendrobium officinale Kimura et Migo (D. officinale) is a well-known traditional Chinese medicine with high content polysaccharides in stems. The SWEET (Sugars Will Eventually be Exported Transporters) family is a novel class of sugar transporters mediating sugar translocation among adjacent cells of plants. The expression patterns of SWEETs and whether they are associated with stress response in D. officinale remains uncovered., Results: Here, 25 SWEET genes were screened out from D. officinale genome, most of which typically contained seven transmembrane domains (TMs) and harbored two conserved MtN3/saliva domains. Using multi-omics data and bioinformatic approaches, the evolutionary relationship, conserved motifs, chromosomal location, expression patterns, correlationship and interaction network were further analyzed. DoSWEETs were intensively located in nine chromosomes. Phylogenetic analysis revealed that DoSWEETs were divided into four clades, and conserved motif 3 specifically existed in DoSWEETs from clade II. Different tissue-specific expression patterns of DoSWEETs suggested the division of their roles in sugar transport. In particular, DoSWEET5b, 5c, and 7d displayed relatively high expression levels in stems. DoSWEET2b and 16 were significantly regulated under cold, drought, and MeJA treatment, which were further verified using RT-qPCR. Correlation analysis and interaction network prediction discovered the internal relationship of DoSWEET family., Conclusions: Taken together, the identification and analysis of the 25 DoSWEETs in this study provide basic information for further functional verification in D. officinale., (© 2023. The Author(s).)

Dendrobium (Orchidaceae, Epidendoideae) plants have flowers with a wide variety of colors that persist for a long period throughout the year. The yellow coloration of Dendrobium flowers is mainly determined by the flavonol pathway and the flavone pathway, but the relevant biosynthesis mechanisms during vernalization remain unclear. To explore the similarities and differences in flavonoid biosynthesis in different tissues during vernalization, we selected two species of Dendrobium for a flower color study: Dendrobium capillipes Rchb (which has yellow flowers) and Dendrobium nobile Lindl (which has white flowers). We collected a total of 36 samples from six tissue types and both Dendrobium species during vernalization and subjected the samples to metabolic profiling and transcriptome sequencing. A total of 31,504 differentially expressed genes (DEGs) were identified between different tissues of the two Dendrobium species by transcriptomic analysis. However, many differentially accumulated metabolites (DAMs) and DEGs were enriched not only in the general pathway of "flavonoid biosynthesis" but also in multiple subpathways of "flavone and flavonol biosynthesis". According to a combined transcriptome and metabolome analysis, Putrescine hydroxycinnamoyl transferase 1 (LOC110093422) may be the main gene responsible for the differences in flavonoid accumulation during vernalization, which is closely associated with yellow flowers. Taken together, the results of our study preliminarily revealed the metabolites responsible for and the key genes regulating flavonoid biosynthesis during vernalization. These results provide a basis for the further study of the molecular mechanism of flavonoid synthesis during vernalization.

The small plant-specific YABBY gene family plays key roles in diverse developmental processes in plants. Dendrobium chrysotoxum , D. huoshanense , and D. nobile are perennial herbaceous plants belonging to Orchidaceae with a high ornamental value. However, the relationships and specific functions of the YABBY genes in the Dendrobium species remain unknown. In this study, six DchYABBY s, nine DhuYABBY s, and nine DnoYABBY s were identified from the genome databases of the three Dendrobium species, which were unevenly distributed on five, eight, and nine chromosomes, respectively. The 24 YABBY genes were classified into four subfamilies (CRC/DL, INO, YAB2, and FIL/YAB3) based on their phylogenetic analysis. A sequence analysis showed that most of the YABBY proteins contained conserved C2C2 zinc-finger and YABBY domains, while a gene structure analysis revealed that 46% of the total YABBY genes contained seven exons and six introns. All the YABBY genes harbored a large number of Methyl Jasmonate responsive elements, as well as anaerobic induction cis -acting elements in the promoter regions. Through a collinearity analysis, one, two, and two segmental duplicated gene pairs were identified in the D. chrysotoxum , D. huoshanense , and D. nobile genomes, respectively. The Ka/Ks values of these five gene pairs were lower than 0.5, indicating that the Dendrobium YABBY genes underwent negative selection. In addition, an expression analysis revealed that DchYABBY2 plays a role in ovary and early-stage petal development, while DchYABBY5 is essential for lip development and DchYABBY6 is crucial for early sepal formation. DchYABBY1 primarily regulates sepals during blooming. Furthermore, there is the potential involvement of DchYABBY2 and DchYABBY5 in gynostemium development. The results of a comprehensive genome-wide study would provide significant clues for future functional investigations and pattern analyses of YABBY genes in different flower parts during flower development in the Dendrobium species.

As a kind of orchid plant with both medicinal and ornamental value, Dendrobium officinale has garnered increasing research attention in recent years. The MYB and bHLH transcription factors play important roles in the synthesis and accumulation of anthocyanin. However, how MYB and bHLH transcription factors work in the synthesis and accumulation of anthocyanin in D. officinale is still unclear. In this study, we cloned and characterized one MYB and one bHLH transcription factor, namely, D. officinale MYB5 (DoMYB5) and D. officinaleb bHLH24 (DobHLH24), respectively. Their expression levels were positively correlated with the anthocyanin content in the flowers, stems, and leaves of D. officinale varieties with different colors. The transient expression of DoMYB5 and DobHLH24 in D. officinale leaf and their stable expression in tobacco significantly promoted the accumulation of anthocyanin. Both DoMYB5 and DobHLH24 could directly bind to the promoters of D. officinale CHS ( DoCHS ) and D. officinale DFR ( DoDFR ) and regulate DoCHS and DoDFR expression. The co-transformation of the two transcription factors significantly enhanced the expression levels of DoCHS and DoDFR . DoMYB5 and DobHLH24 may enhance the regulatory effect by forming heterodimers. Drawing on the results of our experiments, we propose that DobHLH24 may function as a regulatory partner by interacting directly with DoMYB5 to stimulate anthocyanin accumulation in D. officinale .

Background: The auxin indole-3-acetic acid (IAA) is a vital phytohormone that influences plant growth and development. Our previous work showed that IAA content decreased during flower development in the medicinally important orchid Dendrobium officinale, while Aux/IAA genes were downregulated. However, little information about auxin-responsive genes and their roles in D. officinale flower development exists., Results: This study validated 14 DoIAA and 26 DoARF early auxin-responsive genes in the D. officinale genome. A phylogenetic analysis classified the DoIAA genes into two subgroups. An analysis of cis-regulatory elements indicated that they were related by phytohormones and abiotic stresses. Gene expression profiles were tissue-specific. Most DoIAA genes (except for DoIAA7) were sensitive to IAA (10 μmol/L) and were downregulated during flower development. Four DoIAA proteins (DoIAA1, DoIAA6, DoIAA10 and DoIAA13) were mainly localized in the nucleus. A yeast two-hybrid assay showed that these four DoIAA proteins interacted with three DoARF proteins (DoARF2, DoARF17, DoARF23)., Conclusions: The structure and molecular functions of early auxin-responsive genes in D. officinale were investigated. The DoIAA-DoARF interaction may play an important role in flower development via the auxin signaling pathway., (© 2023. The Author(s).)

(1) Background: The extraction parameters can dramatically alter the extraction rate and biological activity of polysaccharides. (2) Methods: Here, an enzyme-assisted extraction (EAE) was employed to extract D. officinale polysaccharides (DOPs), and its optimal extraction conditions were established by single-factor and Box-Behnken design (BBD) experiments. Further, on the basis of in vitro antioxidant capacity, the paraquat (PQ)-induced oxidative stress of Caenorhabditis elegans ( C. elegans ) was chosen as a research model to explore the antioxidant activity of DOPs. (3) Results: The results showed that the extraction yield of DOPs reached 48.66% ± 1.04% under the optimal condition. In vitro experiments had shown that DOPs have considerable ABTS + radical scavenging capacity (EC50 = 7.27 mg/mL), hydroxyl radical scavenging capacity (EC50 = 1.61 mg/mL), and metal chelating power (EC50 = 8.31 mg/mL). Furthermore, in vivo experiments indicated that DOPs (0.25 mg/mL) significantly prolonged the lifespan, increased antioxidant enzyme activity, and upregulated the expression of daf-16 (>5.6-fold), skn-1 (>5.2-fold), and sir-2.1 (>2.3-fold) of C. elegans . (4) Conclusions: DOPs can be efficiently extracted by EAE and are effective in the reduction of oxidative stress levels in C. elegans .

Acute ultraviolet (UV)-B radiation is the major external factor causing photodamage. In this study, we aimed to determine the effects of Dendrobium nobile Lindl. polysaccharides (DNPs) on photodamage in HaCaT keratinocytes after UVB irradiation and the underlying mechanisms. We found that DNPs significantly attenuated the decline in the viability and proliferation of HaCaT cells after UVB irradiation. Moreover, DNPs scavenged reactive oxygen species (ROS), improved the activities of endogenous antioxidant enzymes, including superoxide dismutase, catalase, and glutathione peroxidase, and reduced the levels of malondialdehyde, while partially attenuating cell cycle arrest, suggesting their antioxidant and anti-apoptotic properties. The mitogen-activated protein kinase ( MAPK ) pathway was found to be important for the attenuation of UVB-induced photodamage in the HaCaT cells. Furthermore, DNPs exerted cytoprotective effects by downregulating UVB-induced ROS-mediated phosphorylation of MAPKs, including p38, c-Jun N-terminal kinase, and extracellular signal-regulated kinase, and by inhibiting p53 expression as well as the apoptotic cascade response. Therefore, DNPs ameliorated UVB-induced oxidative damage and apoptosis in HaCaT cells via the regulation of MAPKs . Our findings thus highlight the Dendrobium nobile Lindl polysaccharides as promising therapeutic candidates for UVB-induced photodamage.

Background: Gibberellins (GAs) are widely involved in plant growth and development. DELLA proteins are key regulators of plant development and a negative regulatory factor of GA. Dendrobium officinale is a valuable traditional Chinese medicine, but little is known about D. officinale DELLA proteins. Assessing the function of D. officinale DELLA proteins would provide an understanding of their roles in this orchid's development., Results: In this study, the D. officinale DELLA gene family was identified. The function of DoDELLA1 was analyzed in detail. qRT-PCR analysis showed that the expression levels of all DoDELLA genes were significantly up-regulated in multiple shoots and GA 3 -treated leaves. DoDELLA1 and DoDELLA3 were significantly up-regulated in response to salt stress but were significantly down-regulated under drought stress. DoDELLA1 was localized in the nucleus. A strong interaction was observed between DoDELLA1 and DoMYB39 or DoMYB308, but a weak interaction with DoWAT1., Conclusions: In D. officinale, a developmental regulatory network involves a close link between DELLA and other key proteins in this orchid's life cycle. DELLA plays a crucial role in D. officinale development., (© 2023. The Author(s).)

Dendrobium officinale has remarkable medicinal functions and high economic value. Laser light sources are different from ordinary light sources in terms of the light emission mechanism and play important roles regulating functional metabolite synthesis in D. officinale. However, the mechanism by which miRNAs participate in regulating the D. officinale response to blue laser irradiation has not been reported. Previous studies found that the number of red leaves on plants treated with blue laser light was greater than that on plants treated with blue light and white light, and blue laser light was most effective at promoting the accumulation of total flavonoids, polysaccharides and alkaloids. RNA-seq was used to analyse the difference in the effects of lasers on D. officinale. KEGG analysis of the target genes of differentially expressed (DE) miRNAs showed that there were multiple blue laser response pathways, among which peroxisome, nitrogen metabolism, terpenoid biosynthesis, porphyrin and chlorophyll metabolism played central roles. Cytoscape interaction analysis of DE miRNA targets showed that novel_miR_248 most likely participates in the influence of blue laser irradiation on D. officinale. Content verification in D. officinale showed that blue laser light could also increase the total terpene, chlorophyll levels, nitrate reductase, glutamine synthase and glutamate dehydrogenase. Combined with the qPCR results, these findings showed that miR395b, miR827 and miR319l may participate in the blue laser signalling network through their target genes and then regulate the accumulation of functional metabolites in D. officinale. This study provides a scientific basis for the high-yield production of D. officinale., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

The Dendrobium officinale flower is a non-medicinal part of the plant, rich in a variety of nutrients and bioactive ingredients. The purpose of this article was to explore the preparation conditions of anthocyanins (ACNs) from the D. officinale flower. Subsequently, its anti-aging effects were evaluated with Caenorhabditis elegans . Results showed that the ACNs had antioxidant activities on scavenging free radicals (DPPH· and ABTS + ·), and the clearance rate was positively correlated with the dose. Additionally, ACNs significantly increased the activity of superoxide dismutase (SOD) in C. elegans , which was 2.068-fold higher than that of the control. Treatment with ACNs at 150 μL extended the lifespan of C. elegans by 56.25%, and treatment with ACNs at 50 μL promoted fecundity in C. elegans . Finally, the protective effect of ACNs enhanced stress resistance, thereby increasing the survival numbers of C. elegans , which provided insights for the development and practical application of functional products.

Background: Dendrobium officinale Kimura et Migo, which contains rich polysaccharides, flavonoids and alkaloids, is a Traditional Chinese Medicine (TCM) with important economic benefits, while various pathogens have brought huge losses to its industrialization. NBS gene family is the largest class of plant disease resistance (R) genes, proteins of which are widely distributed in the upstream and downstream of the plant immune systems and are responsible for receiving infection signals and regulating gene expression respectively. It is of great significance for the subsequent disease resistance breeding of D. officinale to identify NBS genes by using the newly published high-quality chromosome-level D. officinale genome., Results: In this study, a total of 655 NBS genes were uncovered from the genomes of D. officinale, D. nobile, D. chrysotoxum, V. planifolia, A. shenzhenica, P. equestris and A. thaliana. The phylogenetic results of CNL-type protein sequences showed that orchid NBS-LRR genes have significantly degenerated on branches a and b. The Dendrobium NBS gene homology analysis showed that the Dendrobium NBS genes have two obvious characteristics: type changing and NB-ARC domain degeneration. Because the NBS-LRR genes have both NB-ARC and LRR domains, 22 D. officinale NBS-LRR genes were used for subsequent analyses, such as gene structures, conserved motifs, cis-elements and functional annotation analyses. All these results suggested that D. officinale NBS-LRR genes take part in the ETI system, plant hormone signal transduction pathway and Ras signaling pathway. Finally, there were 1,677 DEGs identified from the salicylic acid (SA) treatment transcriptome data of D. officinale. Among them, six NBS-LRR genes (Dof013264, Dof020566, Dof019188, Dof019191, Dof020138 and Dof020707) were significantly up-regulated. However, only Dof020138 was closely related to other pathways from the results of WGCNA, such as pathogen identification pathways, MAPK signaling pathways, plant hormone signal transduction pathways, biosynthetic pathways and energy metabolism pathways., Conclusion: Our results revealed that the NBS gene degenerations are common in the genus Dendrobium, which is the main reason for the diversity of NBS genes, and the NBS-LRR genes generally take part in D. officinale ETI system and signal transduction pathways. In addition, the D. officinale NBS-LRR gene Dof020138, which may have an important breeding value, is indirectly activated by SA in the ETI system., (© 2022. The Author(s).)

APETALA2/Ethylene Responsive Factor ( AP2/ERF ) family plays important roles in reproductive development, stress responses and hormone responses in plants. However, AP2/ERF family has not been systematically studied in Dendrobium catenatum . In this study, 120 AP2/ERF family members were identified for the first time in D. catenatum , which were divided into four groups ( AP2 , RAV , ERF and DREB subfamily) according to phylogenetic analysis. Gene structures and conserved motif analysis showed that each DcAP2/ERF family gene contained at least one AP2 domain, and the distribution of motifs varied among subfamilies. Cis-element analysis indicated that DcAP2/ERF genes contained abundant cis-elements related to hormone signaling and stress response. To further identify potential genes involved in drought stress, 12 genes were selected to detect their expression under drought treatment through qRT-PCR analysis and DcAP2/ERF#96 , a nuclear localized ethylene-responsive transcription factor, showed a strong response to PEG treatment. Overexpression of DcAP2/ERF#96 in Arabidopsis showed sensitivity to ABA. Molecular, biochemical and genetic assays indicated that DcAP2ERF#96 interacts with DREB2A and directly inhibits the expression of P5CS1 in response to the ABA signal. Taken together, our study provided a molecular basis for the intensive study of DcAP2/ERF genes and revealed the biological function of DcAP2ERF#96 involved in the ABA signal.

Dendrobium huoshanense , Dendrobium officinale , and Dendrobium moniliforme , as precious Chinese medicinal materials, have a variety of medicinal properties. Flavonoids are important medicinal components of Dendrobium , but their accumulation rules and biosynthesis mechanisms remain unclear. To explore the similarities and differences of flavonoid accumulation and biosynthesis in these three Dendrobium species, we performed flavonoid content determination, widely-targeted metabolomics and transcriptome sequencing on 1-4 years old Dendrobium species. The results showed that in different growth years, D. huoshanense stems had the highest flavonoid content in the second year of growth, while D. officinale and D. moniliforme stems had the highest flavonoid content in the third year of growth. A total of 644 differentially accumulated metabolites (DAMs) and 10,426 differentially expressed genes (DEGs) were identified by metabolomic and transcriptomic analysis. It was found that DAMs and DEGs were not only enriched in the general pathway of "flavonoid biosynthesis", but also in multiple sub-pathways such as "Flavone biosynthesis", and "Flavonol biosynthesis" and "Isoflavonoid biosynthesis". According to a combined transcriptome and metabolome analysis, the expression levels of the F3'H gene ( LOC110096779 ) and two F3'5'H genes ( LOC110101765 and LOC110103762 ) may be the main genes responsible for the differences in flavonoid accumulation. As a result of this study, we have not only determined the optimal harvesting period for three Dendrobium plants, but also identified the key genes involved in flavonoid biosynthesis and provided a basis for further study of the molecular mechanism of flavonoid synthesis.

Background: Flower pigment and shape are determined by the coordinated expression of a set of structural genes during flower development. R2R3-MYB transcription factors are known regulators of structural gene expression. The current study focused on two members of this large family of transcription factors that were predicted to have roles in pigment biosynthesis and organ shape development in orchids., Methods: Phylogenetic analysis was used to identify candidate Dendrobium catenatum R2R3-MYB (DcaMYB) sequences associated with pigment and cell shape development. Gene silencing of candidate DhMYBs in Dendrobium hybrid by direct application of dsRNA to developing flowers was followed by observation of gene expression level and flower phenotypes. Silencing of the structural gene chalcone synthase was used as a comparative control., Key Results: Ten candidate flower-associated DcaMYBs were identified. Flowers treated with dsRNA of DhMYB22 and DhMYB60 sequences were less pigmented and had relatively low expression of anthocyanin biosynthetic genes (F3'H and DFR), lower total anthocyanin concentration and markedly lower levels of cyanidin-3-glucoside and cyanidin-3-rutinoside. Petals of DhMYB22-treated flowers and sepals of DhMYB60-treated flowers showed the greatest colour difference relative to the same organs in untreated flowers. DhMYB22-treated flowers had relatively narrow and constricted lips, while DhMYB60-treated flowers had narrow and constricted sepals. No significant difference in shape was observed for DhCHS-treated or untreated flowers., Conclusions: Our results demonstrate that DhMYB22 and DhMYB60 regulate pigment intensity and floral organ shape in Dendrobium. This is a first report of MYB regulation of floral organ shape in orchids., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Dry eye is one of the most common ocular surface diseases caused by tear film instability and ocular surface damage due to an abnormal quality or quantity of tears. Inflammatory factors can initiate relevant transduction signalling pathways and trigger the inflammatory cascade response, resulting in ocular surface inflammation. It has been shown that the active ingredients in Dendrobium, such as polysaccharides, alkaloids and phenols, have anti-inflammatory, anti-tumour and immunity-boosting effects, and Dendrobium officinale extract can improve glandular secretion function, increase salivary secretion and increase the expression level of water channel protein in salivary glands in patients with dry eye syndromes. We investigated the in vitro cytoprotective effect of Dendrobium extracts in sodium chloride induced hyperosmotic conditions in human cornea keratocytes (HKs). Results showed that Dendrobium officinale Kimura et Migo water extract (DOW) and Dendrobium loddigesii Rolfe water extract (DLW) could upregulate the expression of aquaporins (AQP)5 protein, thus exerting a repairing effect by promoting cell migration. Furthermore, oral administration of DOW and DLW enhanced tear production in rats and exerted a protective effect on ocular surface damage. DOW and DLW could upregulate the expression of AQP5 and mucin (muc)5ac proteins in the lacrimal gland and reduce the inflammatory response. DOW and DLW inhibited the activation of the corresponding mitogen-activated protein kinases (MAPK) and NF-KB pathway, thereby playing a role in improving dry eye symptoms. This study provides a new perspective on dry eye treatment, and DOW and DLW may be potential therapeutic agents for dry eye.

Dendrobium polysaccharide exhibits multiple biological activities, such as immune regulation, antioxidation, and antitumor. However, its resistance to viral infection by stimulating immunity is rarely reported. In this study, we explored the effect and mechanism of DVP-1, a novel polysaccharide from Dendrobium devonianum , in the activation of immunity. After being activated by DVP-1, the ability of mice to prevent H1N1 influenza virus infection was investigated. Results of immune regulation showed that DVP-1 significantly improved the immune organ index, lymphocyte proliferation, and mRNA expression level of cytokines, such as IL-1β, IL-4, IL-6, and TNF-α in the spleen. Immunohistochemical results showed that DVP-1 obviously promoted the mucosal immunity in the jejunum tissue. In addition, the expression levels of TLR4, MyD88, and TRAF6 and the phosphorylation levels of TAK1, Erk, JNK, and NF-κB in the spleen were upregulated by DVP-1. The virus infection results showed that the weight loss of mice slowed down, the survival rate increased, the organ index of the lung reduced, and the virus content in the lung decreased after DVP-1 activated immunity. By activating immunity with DVP-1, the production of inflammatory cells and inflammatory factors in BALF, and alveolar as well as peribronchiolar inflammation could be prevented. The results manifested that DVP-1 could resist H1N1 influenza virus infection by activating immunity through the TLR4/MyD88/NF-κB pathway., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wei, Sun, Zhu, Ou, Zhang, Li, Hu, Qu, Zhong, Yu, You, Wang and Wu.)

Background: Dendrobium catenatum/D. officinale (here after D. catenatum), a well-known economically important traditional medicinal herb, produces a variety of bioactive metabolites including polysaccharides, alkaloids, and flavonoids with excellent pharmacological and clinical values. Although many genes associated with the biosynthesis of medicinal components have been cloned and characterized, the biosynthetic pathway, especially the downstream and regulatory pathway of major medicinal components in the herb, is far from clear. β-glucosidases (BGLUs) comprise a diverse group of enzymes that widely exist in plants and play essential functions in cell wall modification, defense response, phytohormone signaling, secondary metabolism, herbivore resistance, and scent release by hydrolyzing β-D-glycosidic bond from a carbohydrate moiety. The recent release of the chromosome-level reference genome of D. catenatum enables the characterization of gene families. Although the genome-wide analysis of the BGLU gene family has been successfully conducted in various plants, no systematic analysis is available for the D. catenatum. We previously isolated DcBGLU2 in the BGLU family as a key regulator for polysaccharide biosynthesis in D. catenatum. Yet, the exact number of DcBGLUs in the D. catenatum genome and their possible roles in bioactive compound production deserve more attention., Results: To investigate the role of BGLUs in active metabolites production, 22 BGLUs (DcBGLU1-22) of the glycoside hydrolase family 1 (GH1) were identified from D. catenatum genome. Protein prediction showed that most of the DcBGLUs were acidic and phylogenetic analysis classified the family into four distinct clusters. The sequence alignments revealed several conserved motifs among the DcBGLU proteins and analyses of the putative signal peptides and N-glycosylation site revealed that the majority of DcBGLU members dually targeted to the vacuole and/or chloroplast. Organ-specific expression profiles and specific responses to MeJA and MF23 were also determined. Furthermore, four DcBGLUs were selected to test their involvement in metabolism regulation. Overexpression of DcBGLU2, 6, 8, and 13 significantly increased contents of flavonoid, reducing-polysaccharide, alkaloid and soluble-polysaccharide, respectively., Conclusion: The genome-wide systematic analysis identified candidate DcBGLU genes with possible roles in medicinal metabolites production and laid a theoretical foundation for further functional characterization and molecular breeding of D. catenatum., (© 2022. The Author(s).)

Research has shown that dendrobium officinale polysaccharide (DOP) can promote follicular development and inhibit the apoptosis of ovarian granular cells in PCOS rats. However, DOP cannot be absorbed directly by the stomach and small intestine but is degraded into short-chain fatty acids by gut microbiota in the large intestine and regulates the composition of gut microbiota. How DOP improved ovarian function in PCOS rats through the blood-brain barrier is unclear. In this study, we generated letrozole-induced PCOS rat models and studied the therapeutic effect and mechanism of DOP. 16S rRNA amplicon sequencing analysis, GC-MS short-chain fatty acid detection, and Gene Expression Omnibus database searching were conducted to screen the significantly changed pathways, and a series of experiments, such as enzyme-linked immunosorbent assay, RT-qPCR, Western blot, and immunohistochemistry, were performed. We found that DOP treatment could improve ovarian morphology and endocrine disorders, restore the normal estrus cycle, increase gut microbiota α diversity, and alter β diversity and enrichment of butyrate-producing bacterium in PCOS rats. In addition, compared with PCOS rats, those treated with DOP exhibited higher butyrate and polypeptide YY levels, possibly due to the regulation of G protein-coupled receptor 41 expression. These results indicated that DOP relieved the symptoms of PCOS rats which may be related to the mechanism of butyrate dependent gut-brain-ovary axis protection., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Feng, Wang, Hu, Lu, ling, Huang and Jiang.)

Background: Dendrobium officinale is a perennial epiphytic herb in Orchidaceae. Cultivated products are the main alternative for clinical application due to the shortage of wild resources. However, the phenotype and quality of D. officinale have changed post-artificial cultivation, and environmental cues such as light, temperature, water, and nutrition supply are the major influencing factors. This study aims to unveil the mechanisms beneath the cultivation-induced variation by analyzing the changes of the metabolome and transcriptome of D. officinale seedlings treated with red- blue LED light and potassium fertilizer., Results: After light- and K-treatment, the D. officinale pseudobulbs turned purple and the anthocyanin content increased significantly. Through wide-target metabolome analysis, compared with pseudobulbs in the control group (P), the proportion of flavonoids in differentially-accumulated metabolites (DAMs) was 22.4% and 33.5% post light- and K-treatment, respectively. The gene modules coupled to flavonoids were obtained through the coexpression analysis of the light- and K-treated D. officinale transcriptome by WGCNA. The KEGG enrichment results of the key modules showed that the DEGs of the D. officinale pseudobulb were enriched in phenylpropane biosynthesis, flavonoid biosynthesis, and jasmonic acid (JA) synthesis post-light- and K-treatment. In addition, anthocyanin accumulation was the main contribution to the purple color of pseudobulbs, and the plant hormone JA induced the accumulation of anthocyanins in D. officinale ., Conclusions: These results suggested that light and potassium affected the accumulation of active compounds in D. officinale , and the gene-flavone network analysis emphasizes the key functional genes and regulatory factors for quality improvement in the cultivation of this medicinal plant.

Background: Dendrobium Sw. has been used for thousands of years in China as a precious traditional Chinese medicine. It is derived from stems of various Dendrobium plants and has the functions of nourishing Yin and clearing heat, activating water and nourishing the stomach, moistening the lung and relieving cough. Modern phytochemical studies show that the main components of Dendrobium include alkaloids, polysaccharides, terpenoids, diphenylbenzene, and phenanthrene. Alkaloids are natural products with obvious biological activity and are important effective components of the medicinal activity or toxicity of plants. At present, dozens of alkaloids with various structures have been isolated from Dendrobium plants, and the alkaloid contents in Dendrobium plants of different species are quite different. From the perspective of food safety, the type, molecular structure, content and potential physiological activity or toxicity of alkaloids are important bases for evaluating the safety of edible plants. Studies have shown that the alkaloids isolated from Dendrobium have neuroprotective, anti-inflammatory and antitumor activities, showing that these alkaloids with potential medicinal activity are important sources of lead compounds in innovative drug development., Purpose: To summarize the research progress on alkaloids in Dendrobium and provide a reference for research on the food safety and medicinal development of Dendrobium., Method: Information about alkaloids from Dendrobium was collected from the scientific databases Web of Science, PubChem and PubMed. We discuss the biosynthetic pathway, biological activities and total synthesis of alkaloids from Dendrobium from 1964 to 2020 and summarize the knowledge of alkaloids from Dendrobium, the biosynthetic pathway, biological activities and total synthesis. We chose publications on their chemistry, drug effects, pharmacology, metabolism and biosynthesis, physiology and toxicity. Alkaloids, Dendrobium, biosynthetic pathway and biological activities were used as keywords to extract the relevant literature., Conclusion: In this paper, the structural classification, biological activity, target and toxicology and synthesis of the alkaloids in Dendrobium were systematically reviewed, which will provide a reference for the safety, development and application of Dendrobium., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

Although many natural products have proven their potential to regulate obesity through the modulation of adipocyte biology, none of them has yet been approved for clinical use in obesity therapy. This work aims to isolate valuable secondary metabolites from an orchid species ( Dendrobium heterocarpum ) and evaluate their possible roles in the growth and differentiation of 3T3-L1 pre-adipocytes. Six compounds were isolated from the orchid's methanolic extracts and identified as amoenylin ( 1 ), methyl 3-(4-hydroxyphenyl) propionate ( 2 ), 3,4-dihydroxy-5,4'-dimethoxybibenzyl ( 3 ), dendrocandin B ( 4 ), dendrofalconerol A ( 5 ), and syringaresinol ( 6 ). Among these phytochemicals, compounds 2 , 3 , and 6 exhibited lower effects on the viability of 3T3-L1 cells, offering non-cytotoxic concentrations of ≲10 µM. Compared to others tested, compound 3 was responsible for the maximum reduction of lipid storage in 3T3-L1 adipocytes (IC 50 = 6.30 ± 0.10 µM). A set of protein expression studies unveiled that compound 3 at non-cytotoxic doses could suppress the expression of some key transcription factors in adipocyte differentiation (i.e., PPARγ and C/EBPα). Furthermore, this compound could deactivate some proteins involved in the MAPK pathways (i.e., JNK, ERK, and p38). Our findings prove that D . heterocarpum is a promising source to explore bioactive molecules capable of modulating adipocytic growth and development, which can potentially be assessed and innovated further as pharmaceutical products to defeat obesity.

Dendrobium catenatum is a widely cultivated Chinese orchid herb rich in abundant secondary metabolites, such as terpenes. However, terpene distribution and characterization of terpene biosynthesis-related genes remain unknown in D. catenatum. In this study, metabolic profiling was performed to analyze terpene distribution in the root, stem, leaf, and flower of D. catenatum. A total of 74 terpene compounds were identified and classified. Clustering analysis revealed that terpene compounds exhibited a tissue-specific accumulation, including monoterpenes in the flowers, sesquiterpenes in the stems, and triterpenes in the roots. Transcriptome analysis revealed that the ‘terpenoid backbone biosynthesis’ pathway was only significantly enriched in root vs. flower. The expression of terpene biosynthesis-related genes was spatiotemporal in the flowers. Prenylsynthase-terpene synthases (PS-TPSs) are the largest and core enzymes for generating terpene diversity. By systematic sequence analysis of six species, 318 PS-TPSs were classified into 10 groups and 51 DcaPS-TPSs were found in eight of them. Eighteen DcaPS-TPSs were regulated by circadian rhythm under drought stress. Most of the DcaPS-TPSs were influenced by cold stress and fungi infection. The cis-element of the majority of the DcaPS-TPS promoters was related to abiotic stress and plant development. Methyl jasmonate levels were significantly associated with DcaTPSs expression and terpene biosynthesis. These results provide insight into further functional investigation of DcaPS-TPSs and the regulation of terpene biosynthesis in Dendrobium.

Atopic dermatitis (AD) is a chronic inflammatory skin disease that can significantly affect daily life by causing sleep disturbance due to extreme itching. In addition, if the symptoms of AD are severe, it can cause mental disorders such as ADHD and suicidal ideation. Corticosteroid preparations used for general treatment have good effects, but their use is limited due to side effects. Therefore, it is essential to minimize the side effects and study effective treatment methods. Dendrobium nobile Lindley (DNL) has been widely used for various diseases, but to the best of our knowledge, its effect on AD has not yet been proven. In this study, the inhibitory effect of DNL on AD was confirmed in a DNCB-induced Balb/c mouse. In addition, the inhibitory efficacy of inflammatory cytokines in TNF-α/IFN-γ-induced HaCaT cells and PMACI-induced HMC-1 cells was confirmed. The results demonstrated that DNL decreased IgE, IL-6, IL-4, scratching behavior, SCORAD index, infiltration of mast cells and eosinophils and decreased the thickness of the skin. Additionally, DNL inhibited the expression of cytokines and inhibited the MAPK and NF-κB signaling pathways. This suggests that DNL inhibits cytokine expression, protein signaling pathway, and immune cells, thereby improving AD symptoms in mice.

Objectives: Dendrobium catenatum Lindl . (DH) is a Chinese herbal medicine, which is often used to make tea to improve immunity in China. Rumor has it that DH has a protective effect against cardiovascular disease. However, it is not clear how DH can prevent cardiovascular disease, such as atherosclerosis (AS). Therefore, the purpose of this study is to study whether DH can prevent AS and the underlying mechanisms., Methods: Zebrafish larvae were fed with high-cholesterol diet (HCD) to establish a zebrafish AS model. Then, we used DH water extracts (DHWE) to pretreat AS zebrafish. The plaque formation was detected by HE, EVG, and oil red O staining. Neutrophil and macrophage counts were calculated to evaluate the inflammation level. Reactive oxygen species (ROS) activity, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity in zebrafish were measured to reflect oxidative stress. The cholesterol accumulation and the levels of lipid, triglyceride (TG), and total cholesterol (TC) were measured to reflect lipid metabolism disorder. Then, parallel flow chamber was utilized to establish a low shear stress- (LSS-) induced endothelial cell (EC) dysfunction model. EA.hy926 cells were exposed to LSS (3 dyn/cm 2 ) for 30 min and treated with DHWE. The levels of ROS, SOD, MDA, glutathione (GSH), and glutathiol (GSSG) in EA.hy926 cells were analysed to determine oxidative stress. The release of nitric oxide (NO), endothelin-1 (ET-1), and epoprostenol (PGI 2 ) in EA.hy926 cells was measured to reflect EC dysfunction. The mRNA expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in EA.hy926 cells was detected to reflect EC dysfunction inflammation., Results: The results showed that DHWE significantly reduced cholesterol accumulation and macrophage infiltration in early AS. Finally, DHWE significantly alleviate the lipid metabolism disorder, oxidative stress, and inflammation to reduce the plaque formation of AS zebrafish larval model. Meanwhile, we also found that DHWE significantly improved LSS-induced EC dysfunction and oxidative stress in vitro ., Conclusion: Our results indicate that DHWE could be used as a prevention method to prevent AS., Competing Interests: All authors indicated no potential conflicts of interest., (Copyright © 2021 Jichun Han et al.)

Background: Dendrobium catenatum belongs to the Orchidaceae, and is a precious Chinese herbal medicine. In the past 20 years, D. catenatum industry has developed from an endangered medicinal plant to multi-billion dollar grade industry. The necrotrophic pathogen Sclerotium delphinii has a devastating effection on over 500 plant species, especially resulting in widespread infection and severe yield loss in the process of large-scale cultivation of D. catenatum. It has been widely reported that Jasmonate (JA) is involved in plant immunity to pathogens, but the mechanisms of JA-induced plant resistance to S. delphinii are unclear., Results: In the present study, the role of JA in enhancing D. catenatum resistance to S. delphinii was investigated. We identified 2 COI1, 13 JAZ, and 12 MYC proteins in D. catenatum genome. Subsequently, systematic analyses containing phylogenetic relationship, gene structure, protein domain, and motif architecture of core JA pathway proteins were conducted in D. catenatum and the newly characterized homologs from its closely related orchid species Phalaenopsis equestris and Apostasia shenzhenica, along with the well-investigated homologs from Arabidopsis thaliana and Oryza sativa. Public RNA-seq data were investigated to analyze the expression patterns of D. catenatum core JA pathway genes in various tissues and organs. Transcriptome analysis of MeJA and S. delphinii treatment showed exogenous MeJA changed most of the expression of the above genes, and several key members, including DcJAZ1/2/5 and DcMYC2b, are involved in enhancing defense ability to S. delphinii in D. catenatum., Conclusions: The findings indicate exogenous MeJA treatment affects the expression level of DcJAZ1/2/5 and DcMYC2b, thereby enhancing D. catenatum resistance to S. delphinii. This research would be helpful for future functional identification of core JA pathway genes involved in breeding for disease resistance in D. catenatum., (© 2021. The Author(s).)

A major obstacle for orchid (Orchidaceae) breeding and production is a long juvenile phase before orchid reproductive development. The molecular basis for prolonged vegetative growth in orchids remains largely unclear despite many efforts to clarify the relevant mechanisms. In this study, we report functional characterization of Dendrobium Orchid TERMINAL FLOWER1 (DOTFL1), an ortholog of TFL1 in Arabidopsis (Arabidopsis thaliana), from the orchid Dendrobium Chao Praya Smile. DOTFL1 is highly expressed in pseudobulbs and the shoot apical meristem (SAM) before and during the floral transition, but is downregulated in inflorescence apices and open flowers. Ectopic expression of DOTFL1 rescues the early-flowering and terminal-flower phenotypes of tfl1-20 in Arabidopsis. Overexpression of DOTFL1 in Dendrobium orchids delays flowering and produces defective inflorescence meristems and flowers with vegetative traits, whereas knockdown of DOTFL1 accelerates flowering and perturbs the maintenance of the inflorescence meristem. Notably, DOTFL1 suppresses orchid flowering and associated pseudobulb formation during the floral transition. We further reveal that two orchid MADS-box transcription factors, Dendrobium Orchid SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (DOSOC1) and AGAMOUS-LIKE 24 (DOAGL24), could interact with each other and bind to the CArG-box motif at DOTFL1, implying a regulatory hierarchy similar to their counterparts in Arabidopsis. Taken together, our findings suggest that DOTFL1 promotes vegetative growth, modulates successive developmental events required for reproductive success in Dendrobium orchids, and may have evolved with a previously unknown role in controlling pseudobulb formation in the Orchidaceae family., (© American Society of Plant Biologists 2021. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

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.