Search Results (12)

Background: The shift to a parasitic lifestyle in plants often leaves distinct marks on their plastid genomes, given the central role plastids play in photosynthesis. Studying these unique adaptations in parasitic plants is essential for understanding the mechanisms and evolutionary patterns driving plastome reduction in angiosperms. By exploring these changes, we can gain deeper insights into how parasitism reshapes the genomic architecture of plants. Method: This study analyzed and compared the plastomes of 113 parasitic plants from different families. Results: The Orobanchaceae family (hemiparasitic plants) displayed the largest plastome size, while Apodanthaceae exhibited the shortest. Additionally, Orobanchaceae showcased little to no gene loss in their plastomes. However, holoparasitic species typically had reduced plastome sizes. Convolvulaceae exhibited significantly reduced plastome sizes due to high gene loss, and Apodanthaceae retained only a few genes. Gene divergence among different families was also investigated, and rps15, rps18, and rpl33 in Orobanchaceae; accD and ycf1 in Convolvulaceae; atpF and ccsA in Loranthaceae; and rpl32 in Santalaceae showed greater divergence. Additionally, Orobanchaceae had the highest numbers of all repeat types, whereas Loranthaceae and Convolvulaceae exhibited the lowest repeat numbers. Similarly, more simple sequence repeats were reported in Loranthaceae and Santalaceae. Our phylogenetic analysis also uncovered a distinct clade comprising Loranthaceae, with a single Schoepfiaceae species clustering nearby. Contrary to expectations, parasitic and hemiparasitic plants formed mixed groupings instead of segregating into separate clades. Conclusions: These findings offer insights into parasitic plants’ evolutionary relationships, revealing shared and divergent genomic features across diverse lineages. Full article

In the search for new bioactive agents against the infectious pathogen responsible for the neglected tropical disease (NTD) mycetoma, we tested a collection of 27 essential oils (EOs) in vitro against Madurella mycetomatis, the primary pathogen responsible for the fungal form of mycetoma, termed eumycetoma. Among this series, the EO of Santalum album (Santalaceae), i.e., East Indian sandalwood oil, stood out prominently with the most potent inhibition in vitro. We, therefore, directed our research toward 15 EOs of Santalum species of different geographical origins, along with two samples of EOs from other plant species often commercialized as “sandalwood oils”. Most of these EOs displayed similar strong activity against M. mycetomatis in vitro. All tested oils were thoroughly analyzed by GC-QTOF MS and most of their constituents were identified. Separation of the sandalwood oil into the fractions of sesquiterpene hydrocarbons and alcohols showed that its activity is associated with the sesquiterpene alcohols. The major constituents, the sesquiterpene alcohols (Z)-α- and (Z)-β-santalol were isolated from the S. album oil by column chromatography on AgNO₃-coated silica. They were tested as isolated compounds against the fungus, and (Z)-α-santalol was about two times more active than the β-isomer. Full article

In addition to the European mistletoe, Viscum album, which is the most known and utilized one, there are several species commonly known as mistletoe. They are spread in various regions of the planet and are all characterized by hemiparasitism and epiphytic behaviour. The published studies evidence other similarities, including the sharing of important biological properties, with the common presence of antioxidant effects. However, whereas the European mistletoe is largely utilized in medical treatments, although with controversial aspects, the scientific knowledge and medical uses of other mistletoes are still insufficient. This review focuses on the controversial medical story of European mistletoe regarding its antioxidant activity and the potentiality of the other species named mistletoe pertaining to botanical families and genera different from Viscum. Full article

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. Full article

Two shrub-like Thesium species (subgenus Psilothesium) from the Limpopo and North West Provinces in South Africa are treated. Using morphological information from the literature, herbarium material (including types) and geographic information, specimens of the little-known T. celatum N.E.Br. and a new species, T. hispidifructum N.Lombard and M.M.leRoux sp. nov., are treated. A first comprehensive description of the Waterberg–Magaliesberg endemic, T. celatum, is provided along with diagnostic characters to distinguish it from its morphologically most similar-looking species, T. burchellii A.W.Hill. It has hitherto been classified as data deficient due to taxonomic reasons by the International Union for Nature Conservation (IUCN) but a status of Vulnerable is suggested. Thesium hispidifructum is recognised for the first time here and is endemic to Blouberg and Mount Letsjume. It is morphologically most similar to T. disparile N.E.Br. Its name was chosen with reference to its hispidulous to hispid indumentum covering the entire plant including the outside of the flowers and fruit. A threat status of vulnerable is proposed. Treatments of both species include detailed morphological descriptions, information on their distribution and habitat, comparisons and an identification key with morphologically similar species and photo plates. Full article

Despite the common use of Thesium species as food and medicine and the prevailing systematic (taxonomic) difficulties of the genus, the diversity of phenolic compounds and their chemophenetic value remain largely unknown. As part of ongoing systematic research on Thesium, phenolic compounds and their composition were investigated at four taxonomic ranks: generic, infrageneric, interspecific and infraspecific. Liquid chromatography–mass spectrometry, multivariate analyses, comparisons to DNA data and manual investigations of total ion chromatograms were conducted for 156 samples of 50 Thesium species, as well the two monotypic genera sister to Thesium (Lacomucinea and Osyridicarpos). A wide diversity of phenolic compounds, primarily flavonols, carboxylic acids, phenolic acids and associated derivatives, were observed. Rutin was the most common compound, followed by citric acid, isorhamnetin O-glucoside O-rhamnoside, kaempferol O-rutinoside, quinic acid and cryptochlorogenic acid. Chemophenetic data proved valuable at the generic and interspecific level and, to a lesser degree, at the infraspecific level. On the other hand, no distinct patterns were observed at the infrageneric level, nor did chemophenetic data correlate with infrageneric classifications based on genetic, geographical or morphological data. At the generic level, the patterns of phenolic compounds in Lacomucinea and Osyridicarpos overlapped with those of Thesium species, but no compound or group of compounds were unique to Thesium. At the interspecific level, total ion chromatograms of the species were largely distinct from one another and, with the exception of four species, remarkably consistent. Two related species (T. triflorum and T. scandens) with doubtful species boundaries had similar but distinct chromatograms, providing evidence of their retention as separate species. At the infraspecific level, the data were mostly inconclusive, but variation in samples of T. asterias revealed two morphologically distinct populations, one of which is possibly a species new to science. This study provides valuable preliminary insights into the phenolic diversity and chemophenetic relationships in Thesium, Lacomucinaea and Osyridicarpos and highlights the potential of chemophenetics in taxonomically problematic plant groups. Full article

Viscum album L. (Santalaceae), also known as European mistletoe, is a semi-parasitic plant that grows on different host trees. Our group recently demonstrated the antitumoral activity of ethanolic V. album extracts in vitro, depending on the dose and the host tree, V. album ssp abietis from Abies alba being the most active extract. The goal of this work focused on the development of a new topical formulation containing V. album extracts, evaluation of in vitro toxicity and ex vivo skin permeation assays. The Poloxamer 407 hydrogel containing 5% of dry (VA_DEH) or aqueous (VA_AEH) extract presented dermal compatible pH and microbiological stability for 180 days. The hydrogels flow curve presented a non-linear relation, characteristic of non-Newtonian fluids, and the mean viscosity for the VA_DEH and VA_AEH was 372.5 ± 7.78 and 331.0 ± 2.83 Pa.s, respectively, being statistically different (Welch’s t test; p < 0.01). Additionally, WST-1 in vitro assays revealed a dose-dependent toxicity for both formulations and VA_DEH presented a higher activity than the VA_AEH. The promising cytotoxic potential of VA_DEH lead to the ex vivo skin permeation assay with 2.73 ± 0.19 µg/cm² of chlorogenic acid, which permeated at 8 h, showing a transdermal potential. These in vitro results support the idea that VA_DEH is a novel promising candidate for mistletoe therapy. Therefore, further in vivo and pre-clinical experiments should be performed to evaluate the safety and efficacy of this new dermic delivery system. Full article

Santalum (Santalaceae, sandalwood) is a hemiparasitic genus that includes approximately 15 extant species. It is known for its aromatic heartwood oil, which is used in incense and perfume. Demand for sandalwood-based products has led to drastic over-harvesting, and wild Santalum populations are now threatened. Knowledge of phylogenetic relationships will be critical for the conservation and proper management of this genus. Here, we sequenced the chloroplast genome of 11 Santalum species. The data were then used to investigate chloroplast genome evolutionary dynamics and relationships and divergence time within Santalum and related species. The Santalum chloroplast genome contains typical quadripartite structures, ranging from 143,291 to 144,263 bp. The chloroplast genome contains 110 unique genes. The whole set of ndh genes and the infA gene were found to lose their functions. The P-distance among the Santalum species was 0.0003 to 0.00828. Three mutation hotspot regions, 14 small inversions, and 460 indels events were discovered in the Santalum chloroplast genome. Branch-model-based selection analyses showed that the Santalum species were under widespread purifying selection. Our phylogenomic assessment provides an improved resolution to the phylogenetic relationships of Santalum compared to the past analyses. Our divergence time analysis showed that the crown age of Santalum was 8.46 Mya (million years ago), the first divergence occurred around 6.97 Mya, and diversification was completed approximately 1 Mya. By sequencing the 11 Santalum species chloroplast genomes, we identified the variations in the Santalum chloroplast genomes. Using the chloroplast genome sequences, phylogeny and divergence time analyses discovered that the Santalum species were likely to originate due to radiation evolution, and most speciation events occurred less than 1 Mya. Full article

Viscum album L., commonly known as European mistletoe, is a hemi-parasitic plant of the Santalaceae family. The in vitro and in vivo effects of V. album differ, according to its host tree. However, little is known about the host-dependent phytochemical diversity in V. album. In this study, the metabolic profiles of V. album ssp. album from Malus domestica Bork., Quercus robur L., and Ulmus carpinifolia Gled were compared. Leaves, stems, and berries were collected in Switzerland, by the same procedure, in September 2016 and 2017. The methanolic extracts were analyzed by ultra-performance liquid chromatography, coupled to electrospray quadrupole time-of-flight mass spectrometry in positive ionization mode. The data were submitted to partial-least square discriminant analysis (PLS-DA) and the results showed that the V. album ssp. album samples were clustered into three groups, according to the three distinct host trees. Seven compounds, with high VIP scores (variable importance in projection), were responsible for this differentiation. The following four compounds were detected in both the harvest years: arginine, pipecolic acid or lysine, dimethoxycoumarin, and sinapyl alcohol, suggesting their use as host specific V. album biomarkers. The present work highlights the importance of standardized harvest and analytical procedures for the reproducibility of the chemical results of herbal materials. Full article

Genetic diversity and the extent of clonality in a plant species can significantly influence its reproductive success. Whilst clonality can be an effective life-history strategy, in harsh environments it can lead to low levels of diversity and sexual reproductive failure. Santalum lanceolatum (Santalaceae) is a hemi-parasitic shrub endemic to the monsoonal dry tropics of northern Australia, which was harvested for its oil-rich heartwood from natural populations in Cape York, Australia. Despite wild harvesting ending over 70 years ago, populations in the region are currently declining. The aims of this study were to examine genetic variation, population genetic structure, inbreeding and clonality of six S. lanceolatum populations from this northern margin of the species range. Analyses of twelve microsatellite markers showed S. lanceolatum had low genetic diversity (A_R = 2.776, H_E = 0.409), evidence of regional differentiation (F_ST = 0.307–0.424) and negligible inbreeding levels (F = −0.052). Clonality investigations revealed 135 genets among 200 samples, suggesting that the clonal structure of S. lanceolatum may be limiting the potential for sexual reproduction and natural recruitment. We recommend a conservation strategy involving genetic rescue to prevent the further decline and potential local extinction from a variety of environmental pressures and human activities. Full article

The study evaluated species diversity, including regeneration and growth dynamics of different naturally regenerated tree species in gaps of different sizes in a tropical moist semi-deciduous forest, Ghana. Twenty-three randomly selected gaps categorized as small (≤300 m²), medium (301–1000 m²), large (1001–2000 m²), and very large (>2000 m²) sizes were defined. Forty-one subsampling circular 1 m² plots at 2 m intervals were delineated within each gap. In total, 1468 individuals belonging to 85 species from 25 families and 65 genera were enumerated. Malvaceae (13 species) was the most diverse family, while Bignoniaceae, Clusiaceae, Lecythidaceae, Melastomataceae, Mimosaceae, Myristicaceae, Ochnaceae, Rutaceae, Santalaceae, and Urticaceae families were scarcely represented by only 1 species, respectively. Non-pioneer light demanding (NPLD) recorded the highest number of 38 species, followed by pioneers with 30 species, whereas shade-tolerant attained the lowest representatives of 17 species in regenerated species composition. All estimated diversity indices revealed improvements of species diversity in all gaps significantly. Though the small gaps showed no regeneration shift between pioneers and shade-tolerant, the other gap sizes did it at 62–82%. Medium and large gaps promoted natural regeneration at all distinguished diameter classes, however, pioneers and NPLD at 71–100 mm and pioneers at 51–70 mm were absent in small and very large gaps, respectively. Similarly, pioneers of height 0–20 cm in very large gaps were missing. Conclusively, species biodiversity differed significantly among gaps while regeneration dynamics differed significantly among gap sizes. Full article

In our continuing study on a survey of biologically active natural products from heartwood of Santalum album (Southwest Indian origin), we newly found potent fish toxic activity of an n-hexane soluble extract upon primary screening using killifish (medaka) and characterized α-santalol and β-santalol as the active components. The toxicity (median tolerance limit (TLm) after 24 h at 1.9 ppm) of α-santalol was comparable with that of a positive control, inulavosin (TLm after 24 h at 1.3 ppm). These fish toxic compounds including inulavosin were also found to show a significant antifungal effect against a dermatophytic fungus, Trichophyton rubrum. Based on a similarity of the morphological change of the immobilized Trichophyton hyphae in scanning electron micrographs between treatments with α-santalol and griseofulvin (used as the positive control), inhibitory effect of α-santalol on mitosis (the antifungal mechanism proposed for griseofulvin) was assessed using sea urchin embryos. As a result, α-santalol was revealed to be a potent antimitotic agent induced by interference with microtubule assembly. These data suggested that α-santalol or sandalwood oil would be promising to further practically investigate as therapeutic agent for cancers as well as fungal skin infections. Full article