Calcium oxalate in plants: formation and function

Micromorphology, Ultrastructure and Histochemistry of Commelina benghalensis L. Leaves and Stems

Commelina benghalensis L. is used as a traditional medicine in treating numerous ailments and diseases such as infertility in women, conjunctivitis, gonorrhea, and jaundice. This study used light and electron microscopy coupled with histochemistry to investigate the micromorphology, ultrastructure and histochemical properties of C. benghalensis leaves and stems. Stereo and scanning electron microscopy revealed dense non-glandular trichomes on the leaves and stems and trichome density was greater in emergent leaves than in the young and mature. Three morphologically different non-glandular trichomes were observed including simple multicellular, simple bicellular and simple multicellular hooked. The simple bicellular trichomes were less common than the multicellular and hooked. Transmission electron micrographs showed mitochondria, vesicles and vacuoles in the trichome. The leaf section contained chloroplasts with plastoglobuli and starch grains. Histochemical analysis revealed various pharmacologically important compounds such as phenols, alkaloids, proteins and polysaccharides. The micromorphological and ultrastructural investigations suggest that Commelina benghalensis L. is an economically important medicinal plant due to bioactive compounds present in the leaves and stems.

Comparative anatomy and salt management of Sonneratia caseolaris (L.) Engl. (Lythraceae) grown in saltwater and freshwater

Sonneratia caseolaris is a pioneer species in mangrove. It can naturally grow in both saltwater and freshwater. The study was aimed at investigating and comparing the anatomical character of the S. caseolaris plants growing in different conditions and how they coped with salinity. The anatomical characteristics of roots, stems, petioles and leaf blade were investigated. The plant samples were prepared into permanent slides using a paraffin method, while the wood samples were made into permanent slides using a sliding microtome technique. Tissue clearing of leaf blade and scanning electron microscopic analysis of wood were performed. In addition, sodium chloride content in various organs and tissues was examined. It was found that cable root, stem and leaf blade showed some different anatomical characteristics between the two conditions. Periderm is a prominent tissue in saltwater roots. Tanniferous cells were observed in pneumatophores, petioles, stems and leaf blades of saltwater plants, but not found in pneumatophores and lamina of freshwater plants. Mesophyll thickness was lower in the saltwater condition. The vessel density was significantly higher in the saltwater condition than in the freshwater condition, whereas the vessel diameters in the freshwater condition were significantly higher than those in the saltwater condition. From the results, it can be concluded that root periderm plays an important role in salt exclusion, and the occurrence of tanniferous cells is associated with salt elimination.

Heavy metals biosorption mechanism of partially delignified products derived from mango (Mangifera indica) and guava (Psidium guiag) barks

This paper evaluates the biosorption of toxic metal ions onto the bioadsorbents derived from mango (Mangifera indica) and guava (Psidium guiag) barks and their metal fixation mechanisms. Maximum metal biosorption capacities of the mango bioadsorbent were found in the following increasing order (mg/g): Hg (16.24) < Cu (22.24) < Cd (25.86) < Pb (60.85). Maximum metal biosorption capacities of guava bioadsorbent follow similar order (mg/g): Hg (21.48) < Cu (30.36) < Cd (32.54) < Pb (70.25), but with slightly higher adsorption capacities. The removal mechanisms of heavy metals using bioadsorbents have been ascertained by studying their surface properties and functional groups using various spectrometric, spectroscopic, and microscopic methods. Whewellite (C2CaO4·H2O) has been identified in bioadsorbents based on the characterization of their surface properties using X-ray techniques (XPS and XRD), facilitating the ion exchange of metal ions with Ca2+ bonded with carboxylate moieties. For both the bioadsorbents, the Pb2+, Cu2+, and Cd2+ are biosorbed completely by ion exchange with Ca2+ (89-94%) and Mg2+ (7-12%), whereas Hg2+ is biosorbed partially (57-66%) by ion exchange with Ca2+ (38-42%) and Mg2+ (19-24%) due to involvement of other cations in the ion exchange processes. Bioadsorbents contain lignin which act as electron donor and reduced Cr(VI) into Cr(III) (29.87 and 37.25 mg/g) in acidic medium. Anionic Cr(VI) was not adsorbed onto bioadsorbents at higher pH due to their electrostatic repulsion with negatively charged carboxylic functional groups.

The secrets of calcicole species revealed

This article comments on: Kotula L, Clode PL, Ranathunge K, Lambers H. 2021. Role of roots in adaptation of soil-indifferent Proteaceae to calcareous soils in south-western Australia. Journal of Experimental Botany 72, 1490–1505.

Leaf anatomy of two medicinal Croton species: Contribution to plant recognition

Croton L. (Euphorbiaceae) is the second largest genus of the Euphorbiaceae s.l. family, which is composed of about 1,200 taxa. Several species are widely used medicinally in various parts of the world to treat cancer, digestive problems, skin diseases, malaria, ulcers, and obesity. The leaves and stems are sold as dehydrated fragments, or in powder form, and used in the preparation of teas and various types of formulations. The aim of this study was to accurately characterize the leaf anatomy of Croton bonplandianus Baill. and Croton gracilipes Baill. and to perform histochemical analysis of laticifers to provide subsidies for botanical certification. To accomplish this, leaf blade and petiole samples were fixed and prepared following standard techniques for scanning electron and light microscopy. Histochemical tests were carried out on sections to detect the compounds present in the secretions. Results showed neutral and acidic lipids, as well as phenolic compounds, in the latex. In addition, leaf anatomical structures of these two species were studied for specific identification of morphological characters and for quality assessment of these medicinal plants.

Raman imaging reveals in-situ microchemistry of cuticle and epidermis of spruce needles

BACKGROUND

The cuticle is a protective layer playing an important role in plant defense against biotic and abiotic stresses. So far cuticle structure and chemistry was mainly studied by electron microscopy and chemical extraction. Thus, analysing composition involved sample destruction and the link between chemistry and microstructure remained unclear. In the last decade, Raman imaging showed high potential to link plant anatomical structure with microchemistry and to give insights into orientation of molecules. In this study, we use Raman imaging and polarization experiments to study the native cuticle and epidermal layer of needles of Norway spruce, one of the economically most important trees in Europe. The acquired hyperspectral dataset is the basis to image the chemical heterogeneity using univariate (band integration) as well as multivariate data analysis (cluster analysis and non-negative matrix factorization).

RESULTS

Confocal Raman microscopy probes the cuticle together with the underlying epidermis in the native state and tracks aromatics, lipids, carbohydrates and minerals with a spatial resolution of 300 nm. All three data analysis approaches distinguish a waxy, crystalline layer on top, in which aliphatic chains and coumaric acid are aligned perpendicular to the surface. Also in the lipidic amorphous cuticle beneath, strong signals of coumaric acid and flavonoids are detected. Even the unmixing algorithm results in mixed endmember spectra and confirms that lipids co-locate with aromatics. The underlying epidermal cell walls are devoid of lipids but show strong aromatic Raman bands. Especially the upper periclinal thicker cell wall is impregnated with aromatics. At the interface between epidermis and cuticle Calcium oxalate crystals are detected in a layer-like fashion. Non-negative matrix factorization gives the purest component spectra, thus the best match with reference spectra and by this promotes band assignments and interpretation of the visualized chemical heterogeneity.

CONCLUSIONS

Results sharpen our view about the cuticle as the outermost layer of plants and highlight the aromatic impregnation throughout. In the future, developmental studies tracking lipid and aromatic pathways might give new insights into cuticle formation and comparative studies might deepen our understanding why some trees and their needle and leaf surfaces are more resistant to biotic and abiotic stresses than others.

Preparation of novel chemically bonded ceramics with steel slag and potassium hydrogen oxalate

A novel chemically bonded ceramic (novel-CBC) is prepared based on the acid-base reaction of alkali metals in steel slag (SS) and oxalate anion (C₂O₄^2-) in potassium hydrogen oxalate (PO). The effects of SS/PO ratio and water-solid (W/S) ratio on the setting and compressive strength of novel-CBC were studied in this paper. Reaction products and microstructure of novel-CBC were characterized by X-ray diffractometer (XRD), field emission scanning electron microscope-energy dispersive spectroscopy (FESEM-EDS) and thermogravimetric analysis/differential scanning calorimetry (TG/DSC). An optimal formula is obtained at a SS/PO ratio of 3.0 and a W/S ratio of 0.20, which starts setting at 10 min and gives the strengths of 18.0, 25.0, 39.8 and 49.0 MPa at 1, 3, 7 and 28 days, respectively. The reactants from SS are mainly Ca-bearing phases, while only a small amount of RO phase is involved in reaction. The main reaction products of novel-CBC are calcium oxalate monohydrate (CaC₂O₄·H₂O; whewellite) crystals and agglomerates consisting of K, Mg, Al, Si and O elements. The unreacted Ca-bearing phase particle and RO phase residue are embedded in a mixture of abundant CaC₂O₄·H₂O crystals with smooth surfaces and a size of 0.5-1.0 µm with large amounts of the nanoscale agglomerates.

A Systematic Review of Plants With Antibacterial Activities: A Taxonomic and Phylogenetic Perspective

Background: Antimicrobial resistance represents a serious threat to human health across the globe. The cost of bringing a new antibiotic from discovery to market is high and return on investment is low. Furthermore, the development of new antibiotics has slowed dramatically since the 1950s’ golden age of discovery. Plants produce a variety of bioactive secondary metabolites that could be used to fuel the future discovery pipeline. While many studies have focused on specific aspects of plants and plant natural products with antibacterial properties, a comprehensive review of the antibacterial potential of plants has never before been attempted.

Objectives: This systematic review aims to evaluate reports on plants with significant antibacterial activities.

Methods: Following the PRISMA model, we searched three electronic databases: Web of Science, PubMed and SciFinder by using specific keywords: “plant,” “antibacterial,” “inhibitory concentration.”

Results: We identified a total of 6,083 articles published between 1946 and 2019 and then reviewed 66% of these (4,024) focusing on articles published between 2012 and 2019. A rigorous selection process was implemented using clear inclusion and exclusion criteria, yielding data on 958 plant species derived from 483 scientific articles. Antibacterial activity is found in 51 of 79 vascular plant orders throughout the phylogenetic tree. Most are reported within eudicots, with the bulk of species being asterids. Antibacterial activity is not prominent in monocotyledons. Phylogenetic distribution strongly supports the concept of chemical evolution across plant clades, especially in more derived eudicot families. The Lamiaceae, Fabaceae and Asteraceae were the most represented plant families, while Cinnamomum verum, Rosmarinus vulgaris and Thymus vulgaris were the most studied species. South Africa was the most represented site of plant collection. Crude extraction in methanol was the most represented type of extraction and leaves were the main plant tissue investigated. Finally, Staphylococcus aureus was the most targeted pathogenic bacteria in these studies. We closely examine 70 prominent medicinal plant species from the 15 families most studied in the literature.

Conclusion: This review depicts the current state of knowledge regarding antibacterials from plants and provides powerful recommendations for future research directions.

Nano-scale imaging of dual stable isotope labeled oxaliplatin in human colon cancer cells reveals the nucleolus as a putative node for therapeutic effect

Oxaliplatin shows a superior clinical activity in colorectal cancer compared to cisplatin. Nevertheless, the knowledge about its cellular distribution and the mechanisms responsible for the different range of oxaliplatin-responsive tumors is far from complete. In this study, we combined highly sensitive element specific and isotope selective imaging by nanometer-scale secondary ion mass spectrometry (NanoSIMS) with transmission electron microscopy to investigate the subcellular accumulation of oxaliplatin in three human colon cancer cell lines (SW480, HCT116 wt, HCT116 OxR). Oxaliplatin bearing dual stable isotope labeled moieties, i.e. ²H-labeled diaminocyclohexane (DACH) and ¹³C-labeled oxalate, were applied for comparative analysis of the subcellular distribution patterns of the central metal and the ligands. In all the investigated cell lines, oxaliplatin was found to have a pronounced tendency for cytoplasmic aggregation in single membrane bound organelles, presumably related to various stages of the endocytic pathway. Moreover, nuclear structures, heterochromatin and in particular nucleoli, were affected by platinum-drug exposure. In order to explore the consequences of oxaliplatin resistance, subcellular drug distribution patterns were investigated in a pair of isogenic malignant cell lines with distinct levels of drug sensitivity (HCT116 wt and HCT116 OxR, the latter with acquired resistance to oxaliplatin). The subcellular platinum distribution was found to be similar in both cell lines, with only slightly higher accumulation in the sensitive HCT116 wt cells which is inconsistent with the resistance factor of more than 20-fold. Instead, the isotopic analysis revealed a disproportionally high accumulation of the oxalate ligand in the resistant cell line.

Modulation of the calcium oxalate dihydrate to calcium oxalate monohydrate phase transition with citrate and zinc ions

Higher concentrations of Ca2+ and Ox2− can form COD which then transforms to COM. Citrate forms a protective layer to inhibit COD transition; whereas Zn2+ substitutes Ca2+ sites to generate a stable COD structure that retards COM formation.

Mycorrhizal and environmental controls over root trait-decomposition linkage of woody trees

Traits are critical in predicting decomposition that fuels carbon and nutrient cycling in ecosystems. However, our understanding of root trait-decomposition linkage, and especially its dependence on mycorrhizal type and environmental context, remains limited. We explored the control of morphological and chemical (carbon- and nutrient-related) traits over decomposition of absorptive roots in 30 tree species associated with either arbuscular mycorrhizal (AM) or ectomycorrhizal (ECM) fungi in temperate and subtropical forests in China. Carbon-related traits (acid-unhydrolysable residue (AUR) and cellulose concentrations) had predominant control of root decomposition in AM species while nutrient-related traits (magnesium concentration) predominately controlled that in ECM species. Thicker absorptive roots decomposed faster in AM species as a result of their lower AUR concentrations, but more slowly in ECM angiosperm species potentially as a result of their higher magnesium concentrations. Root decomposition was linked to root nutrient economy in both forests while root diameter-decomposition coordination emerged only in the subtropical forest where root diameter and decomposition presented similar cross-species variations. Our findings suggest that root trait-decomposition linkages differ strongly with mycorrhizal type and environment, and that root diameter can predict decomposition but in opposing directions and with contrasting mechanisms for AM and ECM species.

Possible Role of Crystal-Bearing Cells in Tomato Fertility and Formation of Seedless Fruits

Crystal-bearing cells or idioblasts, which deposit calcium oxalate, are located in various tissues and organs of many plant species. The functional significance of their formation is currently unclear. Idioblasts in the leaf parenchyma and the development of crystal-bearing cells in the anther tissues of transgenic tomato plants (Solanum lycopersicon L.), expressing the heterologous FeSOD gene and which showed a decrease in fertility, were studied by transmission and scanning electron microscopy. The amount of calcium oxalate crystals was found to increase significantly in the transgenic plants compared to the wild type (WT) ones in idioblasts and crystal-bearing cells of the upper part of the anther. At the same time, changes in the size and shape of the crystals and their location in anther organs were noted. It seems that the interruption in the break of the anther stomium in transgenic plants was associated with the formation and cell death regulation of a specialized group of crystal-bearing cells. This disturbance caused an increase in the pool of these cells and their localization in the upper part of the anther, where rupture is initiated. Perturbations were also noted in the lower part of the anther in transgenic plants, where the amount of calcium oxalate crystals in crystal-bearing cells was reduced that was accompanied by disturbances in the morphology of pollen grains. Thus, the induction of the formation of crystal-bearing cells and calcium oxalate crystals can have multidirectional effects, contributing to the regulation of oxalate metabolism in the generative and vegetative organs and preventing fertility when the ROS balance changes, in particular, during oxidative stresses accompanying most abiotic and biotic environmental factors.

Dietary fiber components, microstructure, and texture of date fruits (Phoenix dactylifera, L.)

Date fruits vary widely in the hardness of their edible parts and they are classified accordingly into soft, semi-dry, and dry varieties. Fruit texture, a significant parameter in determining consumer acceptance, is related to the tissue structure and chemical composition of the fruit, mainly the ratio of sucrose to reducing sugars. This study aimed to understand the relationship between the chemical composition, microstructure, and texture profile of 10 major Emirati date fruits. The soluble sugars, glucose and fructose, represent ca 80 g/100 g of the fruits on the basis of dry weight (DW) while the dietary fiber contents varied 5.2-7.4 g/100 dg D.W. with lignin being the main determinant of the variability. The textures of the samples were studied using instrumental texture profile analysis. While no correlation was found between the soluble sugar and texture parameters in this study, the different fiber constituents correlated variably with the different parameters of date fruit texture. Lignin, arabinoxylan, galactomannan, and pectin were found to correlate significantly with fruit hardness and the related parameters, gumminess and chewiness. Both lignin and arabinoxylan correlated with resilience, and arabinoxylan exhibited a strong correlation with cohesiveness.

Secretory structures in plants: Lessons from the Plumbaginaceae on their origin, evolution and roles in stress tolerance

The Plumbaginaceae (non-core Caryophyllales) is a family well known for species adapted to a wide range of arid and saline habitats. Of its salt-tolerant species, at least 45 are in the genus Limonium; two in each of Aegialitis, Limoniastrum and Myriolimon, and one each in Psylliostachys, Armeria, Ceratostigma, Goniolimon and Plumbago. All the halophytic members of the family have salt glands and salt glands are also common in the closely related Tamaricaceae and Frankeniaceae. The halophytic species of the three families can secrete a range of ions (Na⁺ , K⁺ , Ca²⁺ , Mg²⁺ , Cl^- , HCO₃^- , SO₄^2- ) and other elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn). Salt glands are, however, absent in salt-tolerant members of the sister family Polygonaceae. We describe the structure of the salt glands in the three families and consider whether glands might have arisen as a means to avoid the toxicity of Na⁺ and/or Cl^- or to regulate Ca²⁺ concentrations with the leaves. We conclude that the establishment of lineages with salt glands took place after the split between the Polygonaceae and its sister group the Plumbaginaceae.

Effects of surface sub-micrometer topography following oxalic acid treatment on bone quantity and quality around dental implants in rabbit tibiae

Background

To explore the effects of topographical modification of titanium substrates at submicron level by oxalic acid treatment on bone quality and quantity around dental implants in rabbit tibiae.

Methods

A total of 60 blasted CP-grade IV titanium dental implants were used. Twenty-eight control implant surfaces were treated with a mixture of HCl/H₂SO₄, whereas 28 other test implant surfaces were treated with oxalic acid following HCl/H₂SO₄ treatment. Two randomly selected sets of control or test implants were placed in randomly selected proximal tibiae of 14 female Japanese white rabbits. Euthanasia was performed 4 and 8 weeks post-implant placement. Bone to implant contact (BIC), bone area fraction (BAF), ratios of mature and immature bone to total bone, and the amount and types of collagen fibers were evaluated quantitatively. Two control and two test implants were used to analyze surface characteristics.

Results

Treatment by oxalic acid significantly decreased Sa and increased Ra of test implant surfaces. BIC in test implants was increased without alteration of BAF and collagen contents at 4 and 8 weeks after implant placement when compared with control implants. The ratios of immature and mature bone to total bone differed significantly between groups at 4 weeks post-implantation. Treatment by oxalic acid increased type I collagen and decreased type III collagen in bone matrices around test implants when compared with control implants at 8 weeks after implant placement. The effects of topographical changes of implant surfaces induced by oxalic acid on BAF, mature bone, collagen contents, and type I collagen were significantly promoted with decreased immature bone formation and type III collagen in the later 4 weeks post-implantation.

Conclusions

Treatment of implant surfaces with oxalic acid rapidly increases osseointegration from the early stages after implantation. Moreover, submicron topographical changes of dental implants induced by oxalic acid improve bone quality based on bone maturation and increased production of type I collagen surrounding dental implants in the late stage after implant placement.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40729-020-00275-x.

Wild Soybean Oxalyl-CoA Synthetase Degrades Oxalate and Affects the Tolerance to Cadmium and Aluminum Stresses

Acyl activating enzyme 3 (AAE3) was identified as being involved in the acetylation pathway of oxalate degradation, which regulates the responses to biotic and abiotic stresses in various higher plants. Here, we investigated the role of Glycine sojaAAE3 (GsAAE3) in Cadmium (Cd) and Aluminum (Al) tolerances. The recombinant GsAAE3 protein showed high activity toward oxalate, with a Km of 105.10 ± 12.30 μM and Vmax of 12.64 ± 0.34 μmol min-1 mg-1 protein, suggesting that it functions as an oxalyl-CoA synthetase. The expression of a GsAAE3-green fluorescent protein (GFP) fusion protein in tobacco leaves did not reveal a specific subcellular localization pattern of GsAAE3. An analysis of the GsAAE3 expression pattern revealed an increase in GsAAE3 expression in response to Cd and Al stresses, and it is mainly expressed in root tips. Furthermore, oxalate accumulation induced by Cd and Al contributes to the inhibition of root growth in wild soybean. Importantly, GsAAE3 overexpression increases Cd and Al tolerances in A. thaliana and soybean hairy roots, which is associated with a decrease in oxalate accumulation. Taken together, our data provide evidence that the GsAAE3-encoded protein plays an important role in coping with Cd and Al stresses.

Protein-driven biomineralization: Comparing silica formation in grass silica cells to other biomineralization processes

Biomineralization is a common strategy adopted by organisms to support their body structure. Plants practice significant silicon and calcium based biomineralization in which silicon is deposited as silica in cell walls and intracellularly in various cell-types, while calcium is deposited mostly as calcium oxalate in vacuoles of specialized cells. In this review, we compare cellular processes leading to protein-dependent mineralization in plants, diatoms and sponges (phylum Porifera). The mechanisms of biomineralization in these organisms are inherently different. The composite silica structure in diatoms forms inside the cytoplasm in a membrane bound vesicle, which after maturation is exocytosed to the cell surface. In sponges, separate vesicles with the mineral precursor (silicic acid), an inorganic template, and organic molecules, fuse together and are extruded to the extracellular space. In plants, calcium oxalate mineral precipitates in vacuolar crystal chambers containing a protein matrix which is never exocytosed. Silica deposition in grass silica cells takes place outside the cell membrane when the cells secrete the mineralizing protein into the apoplasm rich with silicic acid (the mineral precursor molecules). Our review infers that the organism complexity and precursor reactivity (calcium and oxalate versus silicic acid) are main driving forces for the evolution of varied mineralization mechanisms.

Ultrastructure of Cells and Microanalysis in Malus domestica Borkh. 'Szampion' Fruit in Relation to Varied Calcium Foliar Feeding

Calcium is one of the most poorly reutilized nutrients. Its deficiencies cause various physiological disturbances and, consequently, reduce the quantity and quality of yields. Reduced content of Ca²⁺ ions in cells leads to development of, e.g., bitter pit in apples. Efficient and instantaneous mitigation of Ca²⁺ deficiencies is provided by foliar feeding. There are no detailed data on the effect of foliar feeding with various calcium forms on the cell structure or on the microanalysis and mapping of this element in apple fruit cells. Therefore, we carried out comparative studies of the ultrastructure of epidermis and hypodermis cells, to assess the content and distribution of calcium in the cell wall, cytoplasmic membrane, cytoplasm, and precipitates of Malus domestica Borkh. 'Szampion' fruit exposed to four Ca treatments, including the control with no additional Ca supplementation (I) and foliar applications of Ca(NO₃)₂ (II), CaCl₂ (III), and Ca chelated with EDTA (IV). Light and transmission electron microscopy and an X-ray microanalyzer were used and showed a beneficial effect of calcium preparations on the ultrastructure of fruit epidermis and hypodermis cells, manifested in the presence of a normally developed cell wall with a regular middle lamella, preserved continuity of cytoplasmic membranes, and stabilized cell structure. In the selected elements of apical epidermis cells, the highest level of Ca²⁺ ions was detected in the middle lamella, cell wall, plasmalemma, and cytoplasm. The highest increase in the Ca²⁺ content in these cell constituents was recorded in treatment IV, whereas the lowest value of the parameters was noted in variant III.

Recovery of a large herbivore changes regulation of seagrass productivity in a naturally grazed Caribbean ecosystem

What happens in meadows after populations of natural grazers rebound following centuries of low abundance? Many seagrass ecosystems are now experiencing this phenomenon with the recovery of green turtles (Chelonia mydas), large-bodied marine herbivores that feed on seagrasses. These seagrass ecosystems provide a rare opportunity to study ecosystem-wide shifts that result from a recovery of herbivores. We evaluate changes in regulation of seagrass productivity in a naturally grazed tropical ecosystem by (1) comparing Thalassia testudinum productivity in grazed and ungrazed areas and (2) evaluating potential regulating mechanisms of T. testudinum productivity. We established 129 green turtle exclusion cages in grazed and ungrazed areas to quantify T. testudinum growth (linear, area, mass, productivity : biomass [P:B]). In each exclosure, we recorded temperature, irradiance, water depth, nitrogen : phosphorus ratio (N:P) of blade tissue, grazing intensity before cage placement, and T. testudinum structural and nutrient characteristics. Thalassia testudinum exhibited compensatory growth in grazed areas via stimulated blade linear growth, blade area growth, and P:B across seasonal high and low growth periods and in shallow (3-4 m) and deep (9-10 m) seagrass meadows. Irradiance, depth, and N:P ratios had significant roles in regulating mass growth and P:B of T. testudinum in ungrazed areas. Depth was a significant regulating factor of mass growth and P:B in grazed areas; rates were higher and more variable in shallow meadows than in deep meadows. Grazing intensity was also a significant regulating factor for P:B, stimulating tissue turnover with increasing grazing pressure. This study provides important insights into how recovery of a large marine herbivore can result in dramatic, sustainable changes in the regulation of seagrass productivity. We also highlight the need for a historical perspective and use of appropriate indicators, including P:B and grazing intensity, when evaluating seagrass response to green turtle grazing as meadows are returned to a natural grazed state. In an age of green turtle recovery and global seagrass decline due to anthropogenic threats, a thorough understanding of green turtle-seagrass interactions at the ecosystem level is critical to ensure the restoration of seagrass ecosystems and continued recovery of green turtle populations.

Decomposition of Calcium Oxalate Crystals in Colobanthus quitensis under CO2 Limiting Conditions

Calcium oxalate (CaOx) crystals are widespread among plant species. Their functions are not yet completely understood; however, they can provide tolerance against multiple environmental stress factors. Recent evidence suggested that CaOx crystals function as carbon reservoirs since its decomposition provides CO₂ that may be used as carbon source for photosynthesis. This might be advantageous in plants with reduced mesophyll conductance, such as the Antarctic plant Colobanthus quitensis, which have shown CO₂ diffusion limitations. In this study, we evaluate the effect of two CO₂ concentrations in the CaOx crystals decomposition and chlorophyll fluorescence of C. quitensis. Plants were exposed to airflows with 400 ppm and 11.5 ppm CO₂ and the number and relative size of crystals, electron transport rate (ETR), and oxalate oxidase (OxO) activity were monitored along time (10 h). Here we showed that leaf crystal area decreases over time in plants with 11.5 ppm CO₂, which was accompanied by increased OxO activity and only a slight decrease in the ETR. These results suggested a relation between CO₂ limiting conditions and the CaOx crystals decomposition in C. quitensis. Hence, crystal decomposition could be a complementary endogenous mechanism for CO₂ supply in plants facing the Antarctic stressful habitat.

Coupled plant traits adapted to wetting/drying cycles of substrates co-define niche multidimensionality

Theories attempting to explain species coexistence in plant communities have argued in favour of species' capacities to occupy a multidimensional niche with spatial, temporal and biotic axes. We used the concept of hydrological niche segregation to learn how ecological niches are structured both spatially and temporally and whether small scale humidity gradients between adjacent niches are the main factor explaining water partitioning among tree species in a highly water-limited semiarid forest ecosystem. By combining geophysical methods, isotopic ecology, plant ecophysiology and anatomical measurements, we show how coexisting pine and oak species share, use and temporally switch between diverse spatially distinct niches by employing a set of functionally coupled plant traits in response to changing environmental signals. We identified four geospatial niches that turned into nine, when considering the temporal dynamics of the wetting/drying cycles in the substrate and the particular plant species adaptations to garner, transfer, store and use water. Under water scarcity, pine and oak exhibited water use segregation from different niches, yet under maximum drought when oak trees crossed physiological thresholds, niche overlap occurred. The identification of niches and mechanistic understanding of when and how species use them will help unify theories of plant coexistence and competition.

The First Case Series Report of Typhonium trilobatum Tuber Poisoning in Humans

Typhonium is a genus belonging to the Araceae family, native to southern Asia and Australia. In folk medicine, Typhonium is used for its analgesic, anti-inflammatory, antidiarrheal, and wound-healing properties. We report a toxidrome of airway compromise due to Typhonium trilobatum tuber ingestion. We present an interesting case series of four patients who consumed raw tuber of T. trilobatum with suicidal thoughts. They exhibited a constellation of symptoms such as swelling of lips and tongue, drooling of saliva, and severe throat pain. One patient had significant upper airway edema and severe respiratory distress requiring emergency endotracheal intubation. Laboratory investigations were grossly normal in all four individuals, expect for mild asymptomatic hypokalemia in one and eosinophilia in another patient. We successfully managed all our patients with repeated adrenaline nebulization, antihistamines, and steroids. Typhonium is believed to be a beneficial herb. Toxicity of Typhonium is not reported much in the literature till date. An emergency department (ED) physician should be aware of this tuber toxicity as it presents with airway compromise, which resolves over hours. The symptoms are due to the local effects of calcium oxalate crystals in the tuber. Airway management is the priority and repeated adrenaline nebulization together with supportive care is advised.

How to cite this article

Anandhi D, Prakash Raju KNJ, Vivekanandan MP, Kumaresan V. The First Case Series Report of Typhonium trilobatum Tuber Poisoning in Humans. Indian J Crit Care Med 2020;24(7):581-584.

Is There Such a Thing as "Anti-Nutrients"? A Narrative Review of Perceived Problematic Plant Compounds

Plant-based diets are associated with reduced risk of lifestyle-induced chronic diseases. The thousands of phytochemicals they contain are implicated in cellular-based mechanisms to promote antioxidant defense and reduce inflammation. While recommendations encourage the intake of fruits and vegetables, most people fall short of their target daily intake. Despite the need to increase plant-food consumption, there have been some concerns raised about whether they are beneficial because of the various ‘anti-nutrient’ compounds they contain. Some of these anti-nutrients that have been called into question included lectins, oxalates, goitrogens, phytoestrogens, phytates, and tannins. As a result, there may be select individuals with specific health conditions who elect to decrease their plant food intake despite potential benefits. The purpose of this narrative review is to examine the science of these ‘anti-nutrients’ and weigh the evidence of whether these compounds pose an actual health threat.

Metabolome analysis of rice leaves to obtain low-oxalate strain from ion beam-mutagenised population

INTRODUCTION

Rice leaves and stems, which can be used as rice straw for livestock feed, accumulate soluble oxalate. The oxalate content often reaches 5% of the dry weight leaves. Excess uptake of oxalate-rich plants causes mineral deficiencies in vertebrates, so it is important to reduce the oxalate content in rice leaves to produce high-quality rice straw. However, the mechanism of oxalate accumulation in rice has remained unknown.

OBJECTIVES

To understand metabolic networks relating oxalate accumulation in rice.

METHODS

In this study, we performed metabolome analysis of rice M₂ population generated by ion-beam irradiation using CE-MS.

RESULTS

The result showed wide variation of oxalate contents in M₂ plants compared with those of control plants. Multivariate analyses of metabolome dataset revealed that oxalate accumulation was strongly related with anionic compounds such as 2OG and succinate. For low-oxalate plants, four patterns of metabolic alterations affected oxalate contents in the M₂ leaves were observed. In M₃ plants, we found putative low-oxalate line obtained from low-oxalate M₂ mutant.

CONCLUSIONS

These findings would lead to produce the low-oxalate rice and to understand the oxalate synthesis in plants.These findings would lead to produce the low-oxalate rice and to understand the oxalate synthesis in plants.

Absorption and distribution of root, fruit, and foliar-applied 45 Ca in 'Clemenules' mandarin trees

BACKGROUND

The mechanisms of calcium (Ca) absorption and transport in plants are still poorly understood. This study focused on assessing the absorption and distribution of Ca in different plant organs after root (soil), foliar, or fruit application to 6-year-old 'Clemenules' mandarin trees, grown in pots, using ⁴⁵ Ca as a tracer.

RESULTS

The rate of ⁴⁵ Ca absorption and transportation in plant tissues varied according to the treatment method. The fruit and shoot Ca supply led to a rate of 97% to 98% ⁴⁵ Ca retention in such organs. In Ca-treated fruits, 22% of the applied ⁴⁵ Ca moved to the pulp and 78% remained in the flavedo and albedo. The fruit peel was examined by scanning electron microscopy and transmission electron microscopy (SEM and TEM) and variations were observed during fruit development. Following ⁴⁵ Ca soil treatment, approximately 56% of ⁴⁵ Ca activity was measured in the soil, with 19.5% determined in the roots, 14.6% in the trunks (90% in bark and sapwood and only 10% in heartwood), 9.6% in shoots, and 0.3% in fruits.

CONCLUSION

Calcium mobility in 'Clemenules' mandarin trees is limited and depends on the mode of Ca fertilizer application. The distribution of Ca to and within the fruits may be limited during development because of structural and functional constraints. © 2020 Society of Chemical Industry.

Two glyoxylate reductase isoforms are functionally redundant but required under high photorespiration conditions in rice

BACKGROUND

The glyoxylate reductase (GR) multigene family has been described in various plant species, their isoforms show different biochemical features in plants. However, few studies have addressed the biological roles of GR isozymes, especially for rice.

RESULTS

Here, we report a detailed analysis of the enzymatic properties and physiological roles of OsGR1 and OsGR2 in rice. The results showed that both enzymes prefer NADPH to NADH as cofactor, and the NADPH-dependent glyoxylate reducing activity represents the major GR activity in various tissues and at different growth stages; and OsGR1 proteins were more abundant than OsGR2, which is also a major contributor to total GR activities. By generating and characterizing various OsGR-genetically modified rice lines, including overexpression, single and double-knockout lines, we found that no phenotypic differences occur among the various transgenic lines under normal growth conditions, while a dwarfish growth phenotype was noticed under photorespiration-promoted conditions.

CONCLUSION

Our results suggest that OsGR1 and OsGR2, with distinct enzymatic characteristics, function redundantly in detoxifying glyoxylate in rice plants under normal growth conditions, whereas both are simultaneously required under high photorespiration conditions.

Water Shortage Strongly Alters Formation of Calcium Oxalate Druse Crystals and Leaf Traits in Fagopyrum esculentum

Common buckwheat (Fagopyrum esculentum Moench) is a robust plant with high resistance to different environmental constraints. It contains high levels of calcium oxalate (CaOx) druse crystals, although their role remains obscure. The objective was to examine the effects of water shortage on plant biomass partition and leaf traits and formation of CaOx druse crystals in common buckwheat. Buckwheat plants were exposed to favorable and reduced water availability for 28 days. The element composition and morphological, biochemical, physiological and optical traits of the leaves, and the plant biomass were investigated under these conditions. Measurements of photochemical efficiency of photosystem II showed undisturbed functioning for buckwheat exposed to water shortage, apparently due to partially closed stomata and more efficient water regulation. Strong relationships were seen between water-related parameters and Ca, Mn and S content, and size and density of CaOx druse crystals. Redundancy analysis revealed the importance of the size of CaOx druse crystals to explain reflection in the UV range. Water shortage resulted in shorter plants with the same leaf mass (i.e., increased mass:height ratio), which, together with denser leaf tissue and higher content of photosynthetic pigments and protective substances, provides an advantage under extreme weather conditions.

Links between airborne microbiome, meteorology, and chemical composition in northwestern Turkey

The composition of atmospheric aerosols is dynamic and influenced by their emission sources, organic and inorganic composition, transport pathways, chemical and physical processes, microorganisms' content and more. Characterization of such factors can improve the ability to evaluate air quality and health risks under different atmospheric scenarios. Here we investigate the microbial composition of the atmospheric particulate matter (<10 μm; PM₁₀), sampled in Bolu, Turkey, and the linkage to the chemical composition changes, and different environmental factors. We show distinct differences between aerosol composition of different sources and air-mass transport patterns, sampled in July-August 2017 and in February 2018. The summer samples had a typical northern component air mass trajectories and higher local wind speed. They were characterized by high PM₁₀ levels, marine and mineral dust tracers and high relative abundance of Ascomycota, suggesting long-range transport of the particles from remote sources. In contrast, samples collected in February were characterized by a dominant contribution of southern air masses, and low wind speed. They had low PM₁₀ values, higher relative abundance of antibiotic resistance genes and anthropogenic ions related to local industries and farming, suggesting a dominance of local sources. With the microbiome analyses reported here for the first time for this region, we show good agreement between airborne microbial composition, aerosol mass load, chemistry, and meteorology. These results allow better air quality evaluation and prediction capabilities.

High NaCl tolerance potential of Bruguiera cylindrica (L.) Blume compromised by mild CuSO4 concentration as evidenced by unique physiochemical features

Differential response of Bruguiera cylindrica to individual (CuSO₄) and combined (CuSO₄ NaCl) effect was evaluated. The plantlets were treated with control, 0.15 mM CuSO₄, 400 mM NaCl and 0.15 mM CuSO₄ + 400 mM NaCl. Under combined stress, higher accumulation of Cu in the roots indicate that the roots are the primary site of Cu accumulation and thus the plant perform as an excluder and photosynthetic efficiency reduced drastically and significant enhancement in the superoxide and hydroxyl free radicals which increase membrane lipid peroxidation, leading to cellular damage and destruction. As evidenced from SEM-EDXMA, increase in Cu and Na⁺ levels in xylem and pith regions of leaf and stem and the presence of deeply stained structures, denoting the probable formation of complex containing the metal. Increased CaOx crystal forming cells (crystal idioblasts) reveals the regulation of bioaccumulated Cu and Na⁺ by complexing with CaOx. Thus the study suggested that, 400 mM NaCl and 0.15 mM CuSO₄ treatments does not have negative impact on plant growth, the NaCl tolerance potential compromised in the presence of mild CuSO₄ concentration during combined stress.

Evolution of defense and herbivory in introduced plants-Testing enemy release using a known source population, herbivore trials, and time since introduction

The enemy release hypothesis is often cited as a potential explanation for the success of introduced plants; yet, empirical evidence for enemy release is mixed. We aimed to quantify changes in herbivory and defense in introduced plants while controlling for three factors that might have confounded past studies: using a wide native range for comparison with the introduced range, measuring defense traits without determining whether they affect herbivore preferences, and not considering the effect of time since introduction. The first hypothesis we tested was that introduced plants will have evolved lower levels of plant defense compared to their source population. We grew South African (source) and Australian (introduced) beach daisies (Arctotheca populifolia) in a common-environment glasshouse experiment and measured seven defense traits. Introduced plants had more ash, alkaloids, and leaf hairs than source plants, but were also less tough, with a lower C:N ratio and less phenolics. Overall, we found no difference in defense between source and introduced plants. To determine whether the feeding habits of herbivores align with changes in defense traits, we conducted preference feeding trials using five different herbivore species. Herbivores showed no overall preference for leaves from either group. The second hypothesis we tested was that herbivory on introduced plant species will increase through time after introduction to a new range. We recorded leaf damage on herbarium specimens of seven species introduced to eastern Australia and three native control species. We found no change in the overall level of herbivory experienced by introduced plants since arriving in Australia.

CONCLUSION

In the field of invasion ecology, we need to rethink the paradigm that species introduced to a new range undergo simple decreases in defenses against herbivores. Instead, plants are likely to employ a range of defense traits that evolve in both coordinated and opposing ways in response to a plethora of different biotic and abiotic selective pressures.

Characterization of Biominerals in Cacteae Species by FTIR

A biomineral is a crystalline or amorphous mineral product of the biochemical activity of an organism and the local accumulation of elements available in the environment. The cactus family has been characterized by accumulating calcium oxalates, although other biominerals have been detected. Five species of Cacteae were studied to find biominerals. For this, anatomical sections and Fourier transform infrared, field emission scanning electron microscopy and energy dispersive x-ray spectrometry analyses were used. In the studied regions of the five species, they presented prismatic or spherulite dihydrate calcium oxalate crystals, as the predominant biomineral. Anatomical sections of Astrophytum asterias showed prismatic crystals and Echinocactus texensis amorphous silica bodies in the hypodermis. New findings were for Ariocarpus retusus subsp. trigonus peaks assigned to calcium carbonate and for Mammillaria sphaerica peaks belonging to silicates.

Distribution and chemical form of selenium in Neptunia amplexicaulis from Central Queensland, Australia

Selenium (Se), a trace element essential for human and animal biological processes, is deficient in many agricultural soils. Some extremely rare plants can naturally accumulate extraordinarily high concentrations of Se. The native legume Neptunia amplexicaulis, endemic to a small area near Richmond and Hughenden in Central Queensland, Australia, is one of the strongest Se hyperaccumulators known on Earth, with foliar concentrations in excess of 4000 μg Se g^-1 previously recorded. Here, we report on the Se distribution at a whole plant level using laboratory micro X-ray Fluorescence Microscopy (μXRF) and scanning electron microscopy (SEM-EDS), as well as on chemical forms of Se in various tissues using liquid chromatography-mass spectrometry (LC-MS) and synchrotron X-ray absorption spectroscopy (XAS). The results show that Se occurs in the forms of methyl-selenocysteine and seleno-methionine in the foliar tissues, with up to 13 600 μg Se g^-1 total in young leaves. Selenium was found to accumulate primarily in the young leaves, flowers, pods and taproot, with lower concentrations present in the fine-roots and stem and the lowest present in the oldest leaves. Trichomes were not found to accumulate Se. We postulate that Se is (re)distributed in this plant via the phloem from older leaves to newer leaves, using the taproot as the main storage organ. High concentrations of Se in the nodes (pulvini) indicate this structure may play an important a role in Se (re)distribution. The overall pattern of Se distribution was similar in a non-Se tolerant closely related species (Neptunia gracilis), although the prevailing Se concentrations were substantially lower than in N. amplexicaulis.

Suburban areas in flames: Dispersion of potentially toxic elements from burned vegetation and buildings. Estimation of the associated ecological and human health risk

The results of the assessment of burned residential and wildland areas associated with the July 2018 western Attica wildfire are summarised. The dispersion of major and trace elements in a fire impacted suburban landscape which is adjacent in the north with a Natura 2000 area is evaluated. The dataset includes 35 elements and 27 sampling sites spatially distributed in wildland and residential areas. Field observations and a macroscopic method were applied for investigating the wildfire severity. Statistical and spatial analysis tools were used for data treatment. Major and trace element contents were compared to levels and criteria provided by the United States Environmental Protection Agency, Canadian Council of Ministers of the Environment and Australian Department of Environment and Conservation. Aluminum, As, Co, Fe, Mn, Ni, Sb and Zn concentrations observed in wildfire ash pose potential risk to human health. Median ash concentrations for Al, As, B, Ba, Cd, Cu, Fe, Mn, Ni, Pb, S, Sb, and Zn exceeds the plant-avian-mammalian screening levels in wildland and residential areas. Geogenic or anthropogenic origin of the elements is discussed. The associated health risk on human health and terrestrial ecological receptors (plant, avian, mammalian) is assessed.

Risk of Kidney Stones: Influence of Dietary Factors, Dietary Patterns, and Vegetarian-Vegan Diets

Nephrolithiasis is a common medical condition influenced by multiple environmental factors, including diet. Since nutritional habits play a relevant role in the genesis and recurrence of kidney stones disease, dietary manipulation has become a fundamental tool for the medical management of nephrolithiasis. Dietary advice aims to reduce the majority of lithogenic risk factors, reducing the supersaturation of urine, mainly for calcium oxalate, calcium phosphate, and uric acid. For this purpose, current guidelines recommend increasing fluid intake, maintaining a balanced calcium intake, reducing dietary intake of sodium and animal proteins, and increasing intake of fruits and fibers. In this review, we analyzed the effects of each dietary factor on nephrolithiasis incidence and recurrence rate. Available scientific evidence agrees on the harmful effects of high meat/animal protein intake and low calcium diets, whereas high content of fruits and vegetables associated with a balanced intake of low-fat dairy products carries the lowest risk for incident kidney stones. Furthermore, a balanced vegetarian diet with dairy products seems to be the most protective diet for kidney stone patients. Since no study prospectively examined the effects of vegan diets on nephrolithiasis risk factors, more scientific work should be made to define the best diet for different kidney stone phenotypes.

Vitamin C in Plants: Novel Concepts, New Perspectives, and Outstanding Issues

Significance: The concept that vitamin C (l-ascorbic acid) is at the heart of the peroxide processing and redox signaling hub in plants is well established, but our knowledge of the precise mechanisms involved remains patchy at best. Recent Advances: Ascorbate participates in the multifaceted signaling pathways initiated by both reactive oxygen species (ROS) and reactive nitrogen species. Crucially, the apoplastic ascorbate/dehydroascorbate (DHA) ratio that is regulated by ascorbate oxidase (AO) sculpts the apoplastic ROS (apoROS) signal that controls polarized cell growth, biotic and abiotic defences, and cell to cell signaling, as well as exerting control over the light-dependent regulation of photosynthesis. Critical Issues: Here we re-evaluate the roles of ascorbate in photosynthesis and other processes, addressing the question of how much we really know about the regulation of ascorbate homeostasis and its functions in plants, or how AO is regulated to modulate apoROS signals. Future Directions: The role of microRNAs in the regulation of AO activity in relation to stress perception and signaling must be resolved. Similarly, the molecular characterization of ascorbate transporters and mechanistic links between photosynthetic and respiratory electron transport and ascorbate synthesis/homeostasis are a prerequisite to understanding ascorbate homeostasis and function. Similarly, there is little in vivo evidence for ascorbate functions as an enzyme cofactor.

Label-free MS/MS analyses of the dinoflagellate Lingulodinium identifies rhythmic proteins facilitating adaptation to a diurnal LD cycle

Protein levels were assessed in the dinoflagellate Lingulodinium polyedra over the course of a diurnal cycle using a label-free LC-MS/MS approach. Roughly 1700 proteins were quantitated in a triplicate dataset over a daily period, and 13 were found to show significant rhythmic changes. Included among the proteins found to be most abundant at night were the two bioluminescence proteins, luciferase and luciferin binding protein, as well as a proliferating cell nuclear protein involved in the nightly DNA replication. Aconitase and a pyrophosphate fructose-6-phosphate-1-phosphotransferase were also found to be more abundant at night, suggestive of an increased ability to generate ATP by glucose catabolism when photosynthesis does not occur. Among the proteins more abundant during the day were found a 2-epi-5-epi-valiolone synthase, potentially involved in synthesis of mycosporin-like amino acids that can act as a "microbial sunscreen", and an enzyme synthesizing vitamin B6 which is known to protect against oxidative stress. A lactate oxidoreductase was also found to be more abundant during the day, perhaps to counteract the pH changes due to carbon fixation by facilitating conversion of pyruvate to lactate. This unbiased proteomic approach reveals novel insights into the daily metabolic changes of this dinoflagellate. Furthermore, the observation that only a limited number of proteins vary support a model where metabolic flux through pathways can be controlled by variations in a select few, possibly rate limiting, steps. Data are available via ProteomeXchange with identifier PXD006994.

Fractionating of Calcium in Tuber and Leaf Tissues Explains the Calcium Deficiency Symptoms in Potato Plant Overexpressing CAX1

Consistent with reports on other plants we recently reported that a potato transgenic line (AT010901) overexpressing sCAX1 show classic symptoms of calcium deficiency shoot tip injury, leaf curling, leaf margin necrosis and tuber internal defects such as hollow heart and brown spots. The present study was undertaken to quantify calcium in various fraction of leaf and tuber tissues of this transgenic and wild type potato clones to understand the development of these deficiency symptoms at normal calcium nutrition (1mM) and its mitigation at higher calcium nutrition (10mM). Plants were grown in controlled environment growth chamber and watered with balanced nutrient solution containing either 1 or 10 mM calcium. The plants overexpressing sCAX1 showed calcium deficiency symptoms while sequestering calcium in the vacuole as calcium oxalate crystals. Various fractions of calcium were qualified in the young and mature leaves as well as tuber tissue. A reduced concentration of water soluble fraction of calcium was most important factor related to the development of calcium deficiency symptoms in the line overexpressing sCAX1. Furthermore, an increase in this fraction appear to explain the alleviation of the deficiency symptoms in these transgenic plants.Ours is the first study to document the significance of water-soluble calcium in the development of calcium-deficiency symptoms in the potato transgenic lines overexpressing sCAX1. Furthermore, our result demonstrates that an increase in this fraction plays a significant role in the alleviation of calcium deficiency symptoms when calcium concentration in the nutrient media is increased. These results provide important insight on the role of sCAX1 in the calcium homeostasis.

A Rapid Non-Targeted Method for Detecting the Adulteration of Black Pepper with a Broad Range of Endogenous and Exogenous Material at Economically Motivating Levels Using Micro-ATR-FT-MIR Imaging

Infrared spectroscopy is often used as a simple, fast, and green method to screen for economically motivated adulteration in spices. However, conventional microscopy remains the reference method. In this research, the combination of microscopy and Fourier-transform infrared spectroscopy in mapping mode, namely, micro-FTIR imaging, along with Principle Component Analysis were used to develop a non-targeted method for detecting a broad range of organic and mineral bulking agents that could potentially be used to adulterate black pepper. This method, based on the spatial distribution of black pepper chemical composition, has been thoroughly validated as a one-class, non-targeted classification method. Results are categorized as Typical or Atypical, where an Atypical result indicates a high probability of adulteration. For an Atypical outcome, a multitool investigational approach is then used for the detection and identification of the potential adulterant.

Microstructural and histochemical analysis of aboveground organs of Centaurea cyanus used in herbal medicine

Centaurea cyanus L. is a valuable source of many different bioactive substances. It is used in herbal medicine, but the structure of its organs used as raw material and secretory tissues has been insufficiently examined. The aim of this paper was to investigate the microstructure of C. cyanus flowers, bracts, stems and leaves with particular emphasis on secretory structures. Moreover, the main classes of secondary metabolites present in the secretion were identified and the taxonomic value of some micromorphological and anatomical features was analysed. Histochemical, micromorphological and ultrastructural analyses of aboveground organs of C. cyanus were carried out using light, fluorescence, scanning and transmission electron microscopy. The analyses revealed the presence of petal papillae and a characteristic cuticular pattern on the petals, stamens and stylar hairs. There were four types of non-glandular trichomes on the bracts, leaves and stem surfaces. The epidermal cells of the bracts contained prismatic calcium oxalate crystals. Two kinds of secretory structures, i.e. glandular trichomes and ducts, were observed in the C. cyanus organs. The glandular trichomes were located on the bract and stem surfaces, and the ducts were detected in the leaves and stems. Ultrastructural analyses of the epithelium of the ducts showed the presence of strongly osmiophilic insoluble phenolic material in vacuoles as well as moderately osmiophilic insoluble lipidic material in elaioplasts and vesicles. The results of histochemical assays showed a heterogeneous nature of the duct secretion, which contained essential oil, lipids, flavonoids, tannins and terpenes containing steroids.

Estratégias adaptativas foliares de Miconia nervosa (Melastomataceae) na Amazônia Matogrossense

Resumo A plasticidade fenotípica geralmente observada em caracteres morfológicos e anatômicos foliares pode ser influenciada por diversos fatores, como luminosidade, disponibilidade de nutrientes no solo, umidade e herbivoria, entre outros. Testamos essa plasticidade em Miconia nervosa (Melastomataceae) em um fragmento florestal no sul da Amazônia, Mato Grosso - Brasil, buscando verificar possíveis estratégias de aclimatação morfoanatômica à luminosidade. Coletamos folhas totalmente expandidas de 15 indivíduos adultos expostos diretamente à luz solar, nas margens de um lago, e 15 sob o sombreamento do dossel. Avaliamos quantitativamente oito variáveis morfológicas e seis anatômicas, das quais seis e quatro, respectivamente, diferiram significativamente entre folhas de sol e sombra. Morfologicamente, as folhas de sol apresentaram maior tamanho da lâmina foliar e do pecíolo e, anatomicamente, células epidérmicas com paredes levemente mais espessadas, maiores densidades e índice estomático. Folhas de sombra apresentaram epiderme significativamente mais espessa em ambas as faces. As folhas de M. nervosa apresentaram grau mediano a alto de plasticidade nas variáveis morfoanatômicas conforme índice de plasticidade fenotípica, com caracteres mistos de ambientes de sol e sombra. Sugerimos que a distribuição dos indivíduos de M. nervosa na floresta está relacionada à disponibilidade de luz e umidade do solo.

Nitrogen-fixing bacteria and Oxalis - evidence for a vertically inherited bacterial symbiosis

BACKGROUND

Plant-endophyte symbioses often revolve around nitrogen metabolism, and involve varying degrees of intimacy. Although evidence for vertical inheritance of nitrogen-fixing endophytic bacteria is increasing, it is confined mostly to crop plants, and to date no such system has been reported for geophytes.

METHODS

Bacterial endophytes associated with Oxalis, the most species-rich geophytic genus form the Cape Flora in southern Africa was studied. Culturable endophytes were isolated from surface-sterilized vegetative and reproductive plant organs for six host species at three locations. Colonies of microbes on various artificial media were morphotyped, enumerated and identified using sequence data. Filter exclusion experiments were conducted to determine if endophytes were vertically transmitted to seeds, determine if mucilage plays a role to actively attract microbes from the soil and to assess microbial richness isolated from the mucilage of Oxalis seedlings. Fluorescent microscopy was implemented in order to visualize endophytic bacteria in cryo-sectioned seeds.

RESULTS

Evidence for a novel, vertically transmitted symbiosis was reported. Communities of nitrogen-fixing and plant growth-promoting Bacillus endophytes were found to associate with selected Oxalis hosts from nitrogen-deficient environments of the Cape. Bacillus endophytes were ubiquitous and diverse across species and plant bodies, and were prominent in seeds. Three common nitrogen-fixing Bacillus have known oxalotrophic properties and appear to be housed inside specialised cavities (containing oxalates) within the plant body and seeds.

CONCLUSIONS

The discovery of vertical transmission and potential benefits to both host and endophyte suggest a particularly tight mutualism in the Oxalis-endophyte system. This discovery suggests unexpected ways in which geophytes might avoid nitrogen deficiency, and suggest that such symbioses are more common than previously expected.