Micromorphological characterization and electron microscopic study of parasitic species of the family Loranthaceae Juss.

The Loranthaceae Juss. family includes parasitic species that invade important trees such as fruit trees. In Saudi Arabia, Loranthaceae comprises four genera, which include six species that grow in the western, southwestern, and northern regions: Tapinanthus globifer (A.Rich.) Tiegh, Oncocalyx glabratus (Engl.) M. G. Gilbert, Loranthella deflersii (Tiegh.) S. Blanco & C. E. Wetze, Phragmanthera austroarabica A. G. Mill. & J. Nyberg, Plicosepalus curviflorus (Benth.ex Oliv.) Tiegh. and Plicosepalus acaciae (Zucc.). The species present in the Kingdom of Saudi Arabia have not been the subject of enough studies. This work aims to screen and evaluate the taxonomic importance of the micromorphological traits of leaves and fruits in Loranthaceae species native to Saudi Arabia (SA) using scanning electron microscope (SEM). In this study, cluster dendrogram (CD), principal component analysis (PCA) and analysis of variance (ANOVA) were used to evaluate the ability to discriminate Loranthaceae species using micromorphological characteristics. Most of the micromorphological characteristics of the leaf and fruit surfaces used reflected significant variation between the species of Loranthaceae. The type of stomata, trichome, lenticels, fine relief of the cell wall and wax form were the most taxonomically important characteristics. In addition, the cluster dendrogram of morphological characteristics showed species distribution within branches based on affiliation to subtribes Tapinanthinae and Emelianthinae. To the best of our knowledge, the fruit and leaves of the species under study have never been described using electron microscopy, and this study is considered the first of its kind. It also contributes to solving the classification problems of the family Loranthaceae in general and confirms the importance of the characteristics and methods used as tools for characterizing parasitic species that infect trees and helps to verify their identities. This will help to improve resistance efforts and put effective control plans in place.

Immunomodulatory effects of epiphytic Loranthus micranthus leaf extracts collected from two host plants: Psidium guajava and Parkia biglobosa.

BACKGROUND: Immunological abnormalities are implicated in the pathogenesis of many chronic diseases. Due to the drug-related adverse effects of currently available orthodox immunomodulators, natural immunomodulators are being looked upon as potential agents to replace them in therapeutic regimens. This research aimed to investigate the immunomodulatory potential of L. micranthus extracts epiphytic on Psidium guajava (LMPGE) and Parkia biglobosa (LMPBE). METHODS: Phytochemical screening and acute toxicity testing were carried out to identify the phytoconstituents and safety profiles of the extracts. The extracts' innate and adaptive immunomodulatory potentials were determined in experimental animals using in vivo leucocyte mobilization, delayed-type hypersensitivity (DTH) response, hemagglutination antibody titre, and cyclophosphamide-induced myelosuppression models. Levamisole was used as the standard drug throughout the study. RESULTS: Compared to LMPBE, LMPGE contained significantly (p <  0.05) more tannins, cyanogenic glycosides, saponins, reducing sugars, glycosides, flavonoids, and alkaloids. Furthermore, the groups treated with the extracts had a significant (p <  0.05) increase in the total number of leucocytes, neutrophils, basophils, and antibody titers relative to the untreated control. In the same way, the treatment raised TLC in cyclophosphamide-intoxicated rats, with 250 mg/kg b. w. of LMPGE and LMPBE recording 9712.50 ± 178.00 and 8000.00 ± 105.00 ×  109 /L, respectively, compared to 3425.00 ± 2 5.00 × 109 /L in the untreated group. Overall, LMPGE was more effective. CONCLUSIONS: The findings from this study suggest that L. micranthus epiphytic in Psidium guajava and Parkia biglobosa has possible immune stimulating potential.

The pollination ecology of a rare case of bee-pollinated Psittacanthus mistletoe.

The genus Psittacanthus (Loranthaceae) is widely distributed in the Neotropical region, where it is known for its large, colourful, scentless flowers. Until very recently, all Psittacanthus species were regarded as exclusively hummingbird-pollinated and the large species radiation in the genus attributed to the interactions with bird dispersers and pollinators. P. eucalyptifolius (Kunth) G.Don. is the only species reported as bee-pollinated. Here we describe the floral biology, floral visitors, and the reproductive system of P. eucalyptifolius in an Amazonian savanna, Brazil. We also compare the pollination success (reproductive performance) among different Psittacanthus species reported in previous studies. Psittacanthus eucalyptifolius produces sweet-scented flowers, and a small quantity of concentrated nectar. At least five species of scopate bees were recorded visiting and carrying pollen of P. eucalyptifolius. Xylocopa frontalis carried most pollen, visited more flowers, remained longer, and touched reproductive parts of flowers in >95% of the observed visits. Experiments indicate that P. eucalyptifolius is partially autocompatible (39% autonomous pollination) but depends on pollinators to achieve higher performance (~78% in control), indicating that bees can be as effective as birds in pollinating this group of mistletoes.

Differences and biocontrol potential of haustorial endophytic fungi from Taxillus Chinensis on different host plants.

BACKGROUND: To explore the community composition and diversity of the endophytic fungi in Taxillus chinensis, samples of the parasites growing on seven different hosts, Morus alba, Prunus salicina, Phellodendron chinense, Bauhinia purpurea, Dalbergia odorifera, Diospyros kaki and Dimocarpus longan, were isolated. The strains were identified by their morphological characteristics and their internal transcribed spacer (ITS) sequences. RESULTS: 150 different endophytic fungi were isolated from the haustorial roots of the seven hosts with a total isolation rate of 61.24%. These endophytic fungi were found to belong to 1 phylum, 2 classes, 7 orders, 9 families, 11 genera and 8 species. Among of them, Pestalotiopsis, Neopestalotiopsis and Diaporthe were the dominant genera, accounting for 26.67, 17.33 and 31.33% of the total number of strains, respectively. Diversity and similarity analyses showed that the endophytic fungi isolated from D. longan (H'=1.60) had the highest diversity index. The highest richness indexes were found in M. alba and D. odorifera (both 2.23). The evenness index of D. longan was the highest (0.82). The similarity coefficient of D. odorifera was the most similar to D. longan and M. alba (33.33%), while the similarity coefficient of P. chinense was the lowest (7.69%) with M. alba and D. odorifera. Nine strains showed antimicrobial activities. Among them, Pestalotiopsis sp., N. parvum and H. investiens showed significant antifungal activity against three fungal phytopathogens of medicinal plants. At the same time, the crude extracts from the metabolites of the three endophytic fungi had strong inhibitory effects on the three pathogens. Pestalotiopsis sp., N. parvum and H. investiens had the strongest inhibitory effects of S. cucurbitacearum, with inhibitory rates of 100%, 100% and 81.51%, respectively. In addition, N. parvum had a strong inhibitory effect on D. glomerata and C. cassicola, with inhibitory rates of 82.35% and 72.80%, respectively. CONCLUSIONS: These results indicate that the species composition and diversity of endophytic fungi in the branches of T. chinensis were varied in the different hosts and showed good antimicrobial potential in the control of plant pathogens.

Gene Losses and Homology of the Chloroplast Genomes of Taxillus and Phacellaria Species.

Research on the chloroplast genome of parasitic plants is limited. In particular, the homology between the chloroplast genomes of parasitic and hyperparasitic plants has not been reported yet. In this study, three chloroplast genomes of Taxillus (Taxillus chinensis, Taxillus delavayi, and Taxillus thibetensis) and one chloroplast genome of Phacellaria (Phacellaria rigidula) were sequenced and analyzed, among which T. chinensis is the host of P. rigidula. The chloroplast genomes of the four species were 119,941-138,492 bp in length. Compared with the chloroplast genome of the autotrophic plant Nicotiana tabacum, all of the ndh genes, three ribosomal protein genes, three tRNA genes and the infA gene were lost in the three Taxillus species. Meanwhile, in P. rigidula, the trnV-UAC gene and the ycf15 gene were lost, and only one ndh gene (ndhB) existed. The results of homology analysis showed that the homology between P. rigidula and its host T. chinensis was low, indicating that P. rigidula grows on its host T. chinensis but they do not share the chloroplast genome. In addition, horizontal gene transfer was not found between P. rigidula and its host T. chinensis. Several candidate highly variable regions in the chloroplast genomes of Taxillus and Phacellaria species were selected for species identification study. Phylogenetic analysis revealed that the species of Taxillus and Scurrula were closely related and supported that Scurrula and Taxillus should be treated as congeneric, while species in Phacellaria had a close relationship with that in Viscum.

Comparative Analyses of Chloroplast Genomes for Parasitic Species of Santalales in the Light of Two Newly Sequenced Species, Taxillus nigrans and Scurrula parasitica.

When a flowering plant species changes its life history from self-supply to parasite, its chloroplast genomes may have experienced functional physical reduction, and gene loss. Most species of Santalales are hemiparasitic and few studies focus on comparing the chloroplast genomes of the species from this order. In this study, we collected and compared chloroplast genomes of 12 species of Santalales and sequenced the chloroplast genomes of Taxillus nigrans and Scurrula parasitica for the first time. The chloroplast genomes for these species showed typical quadripartite structural organization. Phylogenetic analysis suggested that these 12 species of Santalales clustered into three clades: Viscum (4 spp.) and Osyris (1 sp.) in the Santalaceae and Champereia (1 sp.) in the Opiliaceae formed one clade, while Taxillus (3 spp.) and Scurrula (1 sp.) in the Loranthaceae and Schoepfia (1 sp.) in the Schoepfiaceae formed another clade. Erythropalum (1 sp.), in the Erythropalaceae, appeared as a third, most distant, clade within the Santalales. In addition, both Viscum and Taxillus are monophyletic, and Scurrula is sister to Taxillus. A comparative analysis of the chloroplast genome showed differences in genome size and the loss of genes, such as the ndh genes, infA genes, partial ribosomal genes, and tRNA genes. The 12 species were classified into six categories by the loss, order, and structure of genes in the chloroplast genome. Each of the five genera (Viscum, Osyris, Champereia, Schoepfia, and Erythropalum) represented an independent category, while the three Taxillus species and Scurrula were classified into a sixth category. Although we found that different genes were lost in various categories, most genes related to photosynthesis were retained in the 12 species. Hence, the genetic information accorded with observations that they are hemiparasitic species. Our comparative genomic analyses can provide a new case for the chloroplast genome evolution of parasitic species.

Understanding parasitism in Loranthaceae: Insights from plastome and mitogenome of Helicanthes elastica.

Loranthaceae is the largest family of the order Santalales and includes root and stem hemiparasites. The parasites are known to exhibit reductions in the genomic features as well as relaxed or intensified selection shifts. In this study, we report plastome and mitogenome sequence of Helicanthes elastica (subtribe Amyeminae, tribe Lorantheae), an endemic, monotypic genus of Western Ghats, India growing on remarkably diverse host range. The length of plastome sequence was 1,28,805 bp while that of mitogenome was 1,65,273 bp. This is the smallest mitogenome from Loranthaceae reported till date. The plastome of Helicanthes exhibited loss of ndh genes (ψndhB), ψinfA, rps15, rps16, rpl32, trnK-UUU, trnG-UCC, trnV-UAC and trnA-UGC while mitogenome exhibited pseudogenized cox2, nad1 and nad4 genes. The comparative study of Loranthaceae plastomes revealed that the pseudogenization or loss of genes was not specific to any genus or tribe and variation was noted in the number of introns of clpP gene in the family. Several photosynthetic genes have undergone relaxed selection supporting lower photosynthetic rates in parasitic plants while some respiratory genes exhibited intensified selection supporting the idea of host-parasite arm race in Loranthaceae. The plastome gene content was found conserved in root hemiparasites compared to stem hemiparasites. The atp1 gene of mitogenome was chimeric and part of it exhibited similarities with Lamiales members. The phylogenetic analysis based on plastid genes placed Helicanthes sister to the members of subtribe Dendrophthoinae.

Assessment of the phytochemical composition and antimicrobial properties of Tapinanthus bangwensis leaves hosted by the branches of Persea americana.

BACKGROUND: Medicinal plants represent a valuable source for new effective and safe antimicrobial drugs making them an alternative therapy. Existing antimicrobial agents are costly and mostly associated with possible side effects. The aim of the present study therefore, was to assess the antimicrobial property and phytochemical composition of hydroethanolic extract of Tapinanthus bangwensis leaves and its fractions. METHOD: T. bangwensis leaves (harvested from its host plant, Persea americana) was extracted by cold maceration with 70% ethanol and further fractionated with different organic solvents using the solvent partitioning method to obtain the crude extract, petroleum ether, chloroform, ethyl acetate and the resulting aqueous fractions. The phytochemical constituents of the extracts were screened and quantified. Also, the TLC of the extracts were analyzed to serve as a fingerprint. Using the agar diffusion and broth dilution methods, the antimicrobial properties of the extracts were assessed. RESULTS: The study showed that the hydroethanolic (70%) crude extract of T. bangwensis leaves and its fractions contain phenolic compounds, flavonoids, saponins, phytosterols and reducing sugars. The phytoconstituents were well extracted into the ethyl acetate fraction than the other fractions evidenced in the high levels (p < 0.0001) of saponins (66.47 ± 1.72% w/w), phenolic compounds (77.75 ± 1.06 mg/100 mg GAE) and flavonoids (44.34 ± 0.06 mg/100 mg QE) contents. From the antimicrobial studies, all the microorganisms tested exhibited varying degrees of susceptibility to the extracts with MIC values between 0.78 to 12.5 mg/mL. The crude extract of T. bangwensis leaves, its ethyl acetate and chloroform fractions also exhibited lethal antimicrobial activity with MLC between 6.25 to 50 mg/mL. CONCLUSION: The crude extract of T. bangwensis leaves and its fractions demonstrated antimicrobial properties against Escherichia coli, Staphylococcus aureus, Staphylococcus saprophyticus and Candida albicans, thereby representing a potential source of natural antimicrobial agent. Further study is required to identify and isolate antimicrobial compounds from the plant for the development of the natural bioactive antimicrobial agents.

Antioxidant Activity and Phytopathogenic Control of Extracts and Fraction from Struthanthus calophyllus A.C.Sm. (Loranthaceae).

Phytopathogenic microorganisms cause oxidative stress in host plants, thus affecting agricultural crops. Such stress could be controlled by antioxidant compounds from parasitic plants, given their antioxidant power. This article reports an evaluation of Struthanthus calophyllus antimicrobial activity and antioxidant mechanism by testing different polarity extracts. Antimicrobial activity was evaluated against phytopathogens bacteria (e. g., Erwinia, Pectobacterium, Xanthomonas) using the agar diffusion method. Pectobacterium and Xanthomonas presented growth inhibition zones similar to streptomycin control. Antioxidant activity was determined by measuring total phenol content, DPPH⋅, and ABTS⋅+ radicals-scavenging inhibition percentage (IP). Most polar extracts presented 76,9-95,9 % IP, which correlates with its phenolic content. Besides, Nuclear Magnetic Resonance in a V14-1 sub-fraction from stem ethanolic extract, chose one for highest yield percentage, highest metabolites presence, and antimicrobial activity, showed triterpenic compounds mixture (α-amyrin, ß-amyrin and 24-methylenecycloartanol). Findings in this study are among the first reports for S. calophyllus, even the chemical characterization, that confirm its strong antioxidant and antibacterial activities. Further molecular composition research about parasitic plants could show how unknown compounds may combat pathogenic microorganisms.

Biological and phytochemical characterization of Phragmanthera regularis (Loranthaceae) from Ethiopia.

Phragmanthera regularis is a hemi-parasitic shrub. It is known for treating various health ailments. The aim of this study was to evaluate the antimicrobial activity, toxicity, and chemical characterization of the leaf extracts of P regularis collected from the Schinus molle host plant in Ethiopia. The antimicrobial properties of crude extracts obtained with chloroform, ethyl acetate, methanol, and water solvents were assayed against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The methanol extract significantly inhibited the growth of S. aureus, E. coli and P. aeruginosa were resistant to any of these solvent extracts. The methanol extract was tested at 175, 550, and 2000 mg/kg body weight doses in white mice and did not reveal any toxicity. The LC-MS qTOF analysis detected flavonoids, phenolic acids, and alkaloids in the crude methanol extract. Further study is needed to investigate the effectiveness of these compounds against S. aureus.

Euphol from Tapinanthus sp. Induces Apoptosis and Affects Signaling Proteins in Glioblastoma and Prostate Cancer Cells

BACKGROUND: Plants play an important role in cancer therapy. They are source of natural molecules which can induce apoptosis in cancer cells by affecting molecular mechanisms implicated in cancer progression. The MAP Kinase/ERK1/2 and PI3K/AKT signaling pathways are two classical signaling pathways implicated in cancer progression and constitute therapeutic targets against cancer. This study aimed to evaluate the effect of euphol on MAP Kinase/ERK1/2 and PI3K/AKT signaling pathways in glioblastoma and prostate cancer cells. Euphol is a tetracyclique triterpene alcohol isolated from Tapinanthus sp. which is a hemi parasitic plant belonging to Loranthaceae family. METHODS: Plant powder was extracted by maceration and euphol was isolated and described using respectively column chromatography separation on silica gel and spectroscopic data. Cytotoxic effect of euphol was evaluated using XTT assay and its effect on MAP Kinase/ERK1/2 and PI3K/AKT protein expression was investigated by Western immunoblot analysis. Apotosis was analyzed by evaluating caspase-3/7 activity. RESULTS: Our investigations demonstrated that this compound has an important cytotoxic effect on C6 and U87 MG glioblastoma (GBM) cells and PC-3 prostate cancer cells. Furthermore, euphol-induced apoptosis revealed by elevated caspase 3/7 activity, was correlated with a significant inhibition of MAP kinase/Erk 1/2 and PI3K/Akt signaling pathway in glioblastoma U87 MG cells. The reverse effect was observed in C6 glioblastoma cells, where apoptosis was correlated with a long-lasting activation of Erk 1/2.  In PC-3 cells, euphol had no or limited effect on Erk 1/2 and Akt activity. CONCLUSION: These results indicate that euphol induces cell death in glioblastoma and prostate cancer cells and regulates significantly Erk1/2 and Akt activity in glioblastoma cells.

The Argentine Mistletoes Ligaria cuneifolia (Ruiz & Pav.) Tiegh (Loranthaceae) and Phoradendron liga (Gillies ex Hook. & Arn.) Eichler (Santalaceae). Thirty Years of Research.

Ligaria cuneifolia (Ruiz & Pav.) Tiegh (Loranthaceae) and Phoradendron liga (Gillies ex Hook. & Arn.) Eichler (Santalaceae) are regarded as Argentine mistletoes based on their similarities with the European counterpart, Viscum album L. (Santalaceae). These two species are the most used medicinal plants to treat high blood pressure in the Argentinian population. To provide scientific grounds to their traditional use and therapeutic potential, they were selected as herbal drug candidates. The main findings would support the anti-hypertensive action, the anticholesterolemic and antioxidant features of L. cuneifolia, and immunomodulatory properties for both species. Quercetin-O-glycosides, galloyl glycosides, and proanthocyanidins are present in L. cuneifolia while P. liga shows C-glycosyl flavones and 3-deoxyproanthocyanidins. This review summarizes the phytochemical characterization, medicinal properties and reveals promising results warranting future efforts for further investigation.

Comparative Proteomic Analysis Provides New Insights into the Development of Haustorium in Taxillus chinensis (DC.) Danser.

Taxillus chinensis is an important medicinal and parasitic plant that attacks other plants for living. The development of haustorium is a critical process, imperative for successful parasitic invasion. To reveal the mechanisms underlying haustorium development, we performed an iTRAQ-based proteomics analysis which led to the identification of several differentially abundant proteins (DAPs) in fresh seeds (CK), baby (FB), and adult haustoria (FD). A total of 563 and 785 DAPs were identified and quantified in the early and later developmental stages, respectively. Pathway enrichment analysis revealed that the DAPs are mainly associated with metabolic pathways, ribosome, phenylpropanoid biosynthesis, and photosynthesis. In addition, DAPs associated with the phytohormone signaling pathway changed markedly. Furthermore, we evaluated the content of various phytohormones during different stages of haustoria development. These results indicated that phytohormones are very important for haustorium development. qRT-PCR results validated that the mRNA expression levels were consistent with the expression of proteins, suggesting that our results are reliable. This is the first report on haustoria proteomes in the parasitic plant, Taxillus chinensis, to the best of our knowledge. Our findings will enhance our understanding of the molecular mechanism of haustoria development.

A De Novo Transcriptome Analysis Identifies Cold-Responsive Genes in the Seeds of Taxillus chinensis (DC.) Danser.

Taxillus chinensis (DC.) Danser, a parasitic plant of the Loranthaceae family, grows by attacking other plants. It has a long history of being used in Chinese medicine to treat multiple chronic diseases. We previously observed that T. chinensis seeds are sensitive to cold. In this study, we performed transcriptome sequencing for T. chinensis seeds treated by cold (0°C) for 0 h, 12 h, 24 h, and 36 h. TRINITY assembled 257,870 transcripts from 223,512 genes. The GC content and N50 were calculated as 42.29% and 1,368, respectively. Then, we identified 42,183 CDSs and 35,268 likely proteins in the assembled transcriptome, which contained 1,622 signal peptides and 6,795 transmembrane domains. Next, we identified 17,217 genes (FPKM > 5) and 2,333 differentially expressed genes (DEGs) in T. chinensis seeds under cold stress. The MAPK pathway, as an early cold response, was significantly enriched by the DEGs in the T. chinensis seeds after 24 h of cold treatment. Known cold-responsive genes encoding abscisic acid-associated, aquaporin, C-repeat binding factor (CBF), cold-regulated protein, heat shock protein, protein kinase, ribosomal protein, transcription factor (TF), zinc finger protein, and ubiquitin were deregulated in the T. chinensis seeds under cold stress. Notably, the upregulation of CBF gene might be the consequences of the downregulation of MYB and GATA TFs. Additionally, we identified that genes encoding CDC20, YLS9, EXORDIUM, and AUX1 and wound-responsive family protein might be related to novel mechanisms of T. chinensis seeds exposed to cold. This study is first to report the differential transcriptional induction in T. chinensis seeds under cold stress. It will improve our understanding of parasitic plants in response to cold and provide a valuable resource for future studies.

Tapinanthus species: A review of botany and biology, secondary metabolites, ethnomedical uses, current pharmacology and toxicology.

ETHNOPHARMACOLOGICAL RELEVANCE: Tapinanthus species are hemiparasites that grow on diverse hosts in African regions. Tapinanthus species are locally known as "all purpose herbs" as they are traditionally used to treat various diseases such as diabetes, hypertension, cancer, inflammation, malaria, anemia, anxiety, itching, and so on. AIM OF THE STUDY: A comprehensive review on research outcomes and future perspectives of Tapinanthus species are presented to provide a reference for relevant researchers. MATERIALS AND METHODS: The references regarding Tapinanthus species were retrieved from Google Scholar, Web of Science, Sci-finder, PubMed, Elsevier, Wiley, China National Knowledge Infrastructure, Open Access Library, and SpringerLink between 1963 and 2022. Scientific plant names were provided by "The Plant List" (www.theplantlist.org) and "The world Flora Online" (www.worldfloraonline.org). RESULTS: Even though Tapinanthus species are regarded as notorious pests that can undermine various hosts, they are, as omnipotent herbs in folklore, meaningful for the development of potential phytomedicine sources. Phytochemistry screening has revealed the presence of glycosides, triterpenoids, flavonoids, alkaloids, tannins, steroids, anthraquinones. Among them, the chemical structures of 40 compounds have been elucidated by phytochemical methods without alkaloids and anthraquinones. These secondary metabolites might be responsible for ethnomedical uses and bioactivities of Tapinanthus species. Current research has provided scientific evidence for traditional uses of Tapinanthus species, especially unraveling hypoglycemic, hepatoprotective, antioxidant, antibacterial, anti-anxiety, anti-depression, anti-inflammatory, and other pharmacological properties. Given the fact that ethnomedical uses served as a valuable reference for pharmacology, however, some records to treat arthritis, fever, itching, dysentery, stomach pain, and anemia, have not been confirmed in current research. Furthermore, the toxic effects of Tapinanthus species were susceptible to the dosages, with relative safety across a wide range. CONCLUSIONS: To reasonably yield Tapinanthus species, artificial culture might be a promising method to develop in the future. The discrepancies between phytochemistry screening and structure elucidation, as well as between ethnomedical uses and current pharmacology, need to be further clarified. The identification of bioactive compounds in crude extracts and fractions, the illustration of the underlying mechanisms of pharmacology, along with the addition of cytotoxicity, genotoxicity, and clinical trials of toxic tests, should be carried out in depth. This review highlights that Tapinanthus species can be considered promising phytomedicine sources as long as we adhere to digging more deeply into their potential role.

Effects of endophytic fungi on parasitic process of Taxillus chinensis.

Taxillus chinensis (DC.) Danser is an extensively used medicinal shrub in the traditional as well as modern systems of medicines. It is a perennial hemiparasitic plant, which is difficult to propagate artificially because of its low parasitic rate. Successful parasitism of parasitic plants is to fuse their tissues and connect their vasculature to the host vasculature building a physiological bridge, which can efficiently withdraw water, sugars and nutrients from their host plants. It is reported that endophytic fungi play an important role in cell wall degradation and fusion, which is the key forming process of the physiological bridge. Therefore, in this study, the endophytic fungi from T. chinensis of different hosts were isolated, and then the organisms that could degrade the main components of the cell walls were screened out using a medium consisting of guaihuol and cellulose degradation capacity. The results showed that five strains were screened out from 72 endophytic fungi of T. chinensis which with high enzyme activities for lignocellulosic degradation. The laccase and cellulase activities of five strains reached their peaks at day 7, and the highest enzyme activities of these two enzymes were found in strain P6, which was 117.66 and 1.66 U/mL, respectively. Manganese peroxidase of strain 4 and lignin peroxidase of strain N6 also reached their peaks at day 7 and were the highest among the 5 strains, with enzyme activities of 11.61 and 6.64 U/mL, respectively. Strains 4, 15, 31, N6 and P6 were identified as Colletotrichum sp., Nigerrospora sphaerica, Exserohilum sp., Diaporthe phaseolorum and Pestalotiopsis sp., respectively, according to their morphological and molecular biology properties. The endophytic fungi may secrete efficient cell wall degradation enzymes, which promote the dissolution and relaxation of the cell wall between T. chinensis and host, thus contributing to the parasitism of T. chinensis.

Chromosome-Level Genome Assembly of the Hemiparasitic Taxillus chinensis (DC.) Danser.

The hemiparasitic Taxillus chinensis (DC.) Danser is a root-parasitizing medicinal plant with photosynthetic ability, which is lost in other parasitic plants. However, the cultivation and medical application of the species are limited by the recalcitrant seeds of the species, and even though the molecular mechanisms underlying this recalcitrance have been investigated using transcriptomic and proteomic methods, genome resources for T. chinensis have yet to be reported. Accordingly, the aim of the present study was to use nanopore, short-read, and high-throughput chromosome conformation capture sequencing to construct a chromosome-level assembly of the T. chinensis genome. The final genome assembly was 521.90 Mb in length, and 496.43 Mb (95.12%) could be grouped into nine chromosomes with contig and scaffold N50 values of 3.80 and 56.90 Mb, respectively. In addition, a total of 33,894 protein-coding genes were predicted, and gene family clustering identified 11 photosystem-related gene families, thereby indicating photosynthetic ability, which is a characteristic of hemiparasitic plants. This chromosome-level genome assembly of T. chinensis provides a valuable genomic resource for elucidating the genetic basis underlying the recalcitrant characteristics of T. chinensis seeds and the evolution of photosynthesis loss in parasitic plants.

(-)-Brunneusine, a new phenolic compound with antibacterial properties in aqueous medium from the leaves of Agelanthus brunneus (Engl.) Tiegh (LORANTHACEAE).

Agelanthus brunneus (Loranthaceae) is a hemiparasitic plant growing on Senna siamea (Fabaceae). The chemical investigation of its leaves and flowers led to the isolation of one new phenolic compound namely (-)-brunneusine (1), together with 13 known compounds. The crude leaves and flowers extracts (CLE and CFLE) with their ethyl acetate fractions (EAFL and EAFFL) and some isolated compounds (1-3; 8-9 and 11-14) have been tested on four bacterial species of sanitary importance isolated in an aquatic environment. All the samples except compound 3 showed antibacterial activity with MICs ranging from 0.43 to 8.88.103 µg/mL and MBCs from 0.43 to 3.55.103 µg/mL. Compounds 9 and 14 showed better activity on all bacterial species tested with MICs ranging from 0.43 to 27.77 µg/mL. Only CLE, EAFL and compounds 14, 2, 8 and 9 showed bactericidal effects on all bacterial species tested.

A new flavonoid glycoside from Tapinanthus sp. (Loranthaceae) and evaluation of anticancer activity of extract and some isolated compounds.

The present work describes the isolation and anticancer activity of Tapinanthus sp. which is a hemi parasitic plant harvested on Combretum glutinosum, the host plant. Phytochemical study afforded a new flavonoid glycoside, tapinantoside (1) isolated for the first time from natural source, alongside six known compounds (2-7). Structure of compounds were elucidated by extensive spectroscopic analyses including 1 D and 2 D NMR, mass spectrometry and by comparison with literature data. The anticancer activity of extract and some isolated compounds were evaluated on glioblastoma (U87MG, C6) and prostate (PC-3) cancer cells. The methanol leaves extract showed good anticancer activity against U87 (IC50 = 21.40 µg/mL) and PC-3 cells (IC50 = 10.26 µg/mL). Compound 3 powerfully inhibits the proliferation of C6 (IC50 = 38.84 µM) and PC-3 cells (IC50 = 21.33 µM), while its effect was moderated on U87MG cells. Compound 1 and 7 were not active on all tested cancer cell lines.

Macrotricolorin A, a new diarylpropanoid from the Vietnamese plant Macrosolen tricolor (Lecomte) Danser.

From the Vietnamese plant Macrosolen tricolor (Lecomte) Danser, one new diarylpropanoid, named macrotricolorin A (1) together with three diarylheptanoids including bisdemethoxycurcumin (2), demethoxycurcumin (3) and curcumin (4), were isolated. Their structures were elucidated by intensive analyses of their IR, UV, HR-ESI-MS and NMR (1 D & 2 D) spectra. It is the first time that diarylalkanoids have been reported from the genus Macrosolen. Compound 1 exhibited anti-inflammatory activity against the nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 with an IC50 value of 27.54 ± 1.75 µM.