Variation of the Main Alkaloid Content in Equisetum palustre L. in the Light of Its Ontogeny.

Marsh horsetail (Equisetum palustre L.) is one of the most poisonous plants of wet grasslands in the northern hemisphere, which poses a major health threat to livestock. Available data on the levels of its main alkaloids are currently contradictory due to the inadequate analytical methods and the wide variation in toxicity levels reported. Here, we tested the hypothesis that the ontogenetic stage of plant development may explain a significant part of the variations in the main Equisetum-type alkaloids. Two populations of marsh horsetail were sampled over two growing seasons. The plant material was classified according to their developmental stages and subsequently the main alkaloids were determined by hydrophilic interaction liquid chromatography and high-performance liquid chromatography electrospray tandem mass spectrometry (HILIC HPLC-ESI-MS/MS) analysis. ANOVA revealed significant effects of the ontogenetic stage but not the site on the main Equisetum-type alkaloids (sum of palustrine and palustridiene) ranging from 213 to 994 mg/kg dry matter (DM). The highest alkaloid content was found in the stages of early development. Not the season itself, but the growth temperature co-influenced the alkaloid content. Our results help to resolve the seemingly contradictory information provided by previous studies on the toxicity of E. palustre and are of practical relevance for the prevention of contamination risks in wet grassland use.

Effects of graywater on the growth and survival of ornamental plants in nature-based systems.

The current paper investigates the development of two ornamental plants, canna lily (Canna x generalis) and giant horsetail (Equisetum giganteum), at both bench and pilot scale. Combinations of gravel-filled mesocosm, planted and unplanted (control), irrigated with light greywater (GWL) or tap water (WT), were used. Both species were able to grow under the tested conditions with no indication of toxicity that could affect the development. Irrigation with GWL, resulted in higher evapotranspiration (2.2 mm-2.8 mm) in canna lily than giant horsetail (1.7 mm-2.3 mm) in mesocosm system. When the plants were mature and the season was more humid and warmer, canna lily and giant horsetail irrigated with GWL evapotranspirated 69.23% and 30.77%, respectively as compared to the unplanted GWL-irrigated-mesocosm. Principal components and cluster analysis identified similarity between evapotranspiration (ET) and the characteristics of the plants. Both species can thus be used in constructed wetlands taking into consideration elements such as the space available, level of water and solar incidence so as to allow the full development of the plants. The roots of giant horsetail require high water availability. Low solar incidence is indicated for giant horsetail, and the opposite for canna lily, if flowering is desired.

Rough and tough. How does silicic acid protect horsetail from fungal infection?

Horsetail (Equisetum arvense) plants grew healthily for 10 weeks under both Si-deficient and Si-replete conditions. After 10 weeks, plants grown under Si-deficient conditions succumbed to fungal infection. We have used NanoSIMS and fluorescence microscopy to investigate silica deposition in the tissues of these plants. Horsetail grown under Si-deficient conditions did not deposit identifiable amounts of silica in their tissues. Plants grown under Si-replete conditions accumulated silica throughout their tissues and especially in the epidermis of the outer side of the leaf and the furrow region of the stem where it was continuous and often, as a double layer suggestive of a barrier function. We have previously shown, both in vivo (in horsetail and thale cress) and in vitro (using an undersaturated solution of Si(OH)4), that callose is a "catalyst" of plant silica deposition. Here we support this finding by comparing the deposition of silica to that of callose and by showing that they are co-localized. We propose the existence of a synergistic mechanical protection by callose and silica against pathogens in horsetail, whereby the induction of callose synthesis and deposition is the first, biochemical line of defence and callose-induced precipitation of silica is the second, adventitious mechanical barrier.

Developmental programmes in the evolution of Equisetum reproductive morphology: a hierarchical modularity hypothesis.

Background: The origin of the Equisetum strobilus has long been debated and the fossil record has played an important role in these discussions. The paradigm underlying these debates has been the perspective of the shoot as node-internode alternation, with sporangiophores attached at nodes. However, fossils historically excluded from these discussions (e.g. Cruciaetheca and Peltotheca ) exhibit reproductive morphologies that suggest attachment of sporangiophores along internodes, challenging traditional views. This has rekindled discussions around the evolution of the Equisetum strobilus, but lack of mechanistic explanations has led discussions to a stalemate. Scope: A shift of focus from the node-internode view to a perspective emphasizing the phytomer as a modular unit of the shoot, frees the debate of homology constraints on the nature of the sporangiophore and inspires a mechanism-based hypothesis for the evolution of the strobilus. The hypothesis, drawing on data from developmental anatomy, regulatory mechanisms and the fossil record, rests on two tenets: (1) the equisetalean shoot grows by combined activity of the apical meristem, laying down the phytomer pattern, and intercalary meristems responsible for internode elongation; and (2) activation of reproductive growth programmes in the intercalary meristem produces sporangiophore whorls along internodes. Conclusions: Hierarchical expression of regulatory modules responsible for (1) transition to reproductive growth; (2) determinacy of apical growth; and (3) node-internode differentiation within phytomers, can explain reproductive morphologies illustrated by Cruciaetheca (module 1 only), Peltotheca (modules 1 and 2) and Equisetum (all three modules). This model has implications - testable by studies of the fossil record, phylogeny and development - for directionality in the evolution of reproductive morphology ( Cruciaetheca - Peltotheca - Equisetum ) and for the homology of the Equisetum stobilus. Furthermore, this model implies that sporangiophore development is independent of node-internode identity, suggesting that the sporangiophore represents the expression of an ancestral euphyllophyte developmental module that pre-dates the evolution of leaves.

The remarkable stomata of horsetails (Equisetum): patterning, ultrastructure and development.

BACKGROUND AND AIMS: The stomata of Equisetum - the sole extant representative of an ancient group of land plants - are unique with respect to both structure and development, yet little is known about details of ultrastructure and patterning, and existing accounts of key developmental stages are conflicting. METHODS: We used light and electron microscopy to examine mature stomata and stomatal development in Equisetum myriochaetum, and compared them with other land plants, including another putative fern relative, Psilotum We reviewed published reports of stomatal development to provide a comprehensive discussion of stomata in more distantly related taxa. KEY RESULTS: Stomatal development in Equisetum is basipetal and sequential in strict linear cell files, in contrast with Psilotum, in which stomatal development occurs acropetally. In Equisetum, cell asymmetry occurs in the axial stomatal cell file, resulting in a meristemoidal mother cell that subsequently undergoes two successive asymmetric mitoses. Each stomatal cell complex is formed from a single precursor meristemoid, and consists of four cells: two guard cells and two mesogene subsidiary cells. Late periclinal divisions occur in the developing intervening cells. CONCLUSIONS: In addition to the unique mature structure, several highly unusual developmental features include a well-defined series of asymmetric and symmetric mitoses in Equisetum, which differs markedly from Psilotum and other land plants. The results contribute to our understanding of the diverse patterns of stomatal development in land plants, including contrasting pathways to paracytic stomata. They add to a considerable catalogue of highly unusual traits of horsetails - one of the most evolutionarily isolated land-plant taxa.

Pesticide residues in some herbs growing in agricultural areas in Poland.

The aim of this paper was to assess residue content of plant protection products in selected herbs: Achillea millefolium L., Cichorium intybus L., Equisetum arvense L., Polygonum persicaria L., Plantago lanceolata L., and Plantago major L. The study comprises herbs growing in their natural habitat, 1 and 10 m away from crop fields. The herbs, 30 plants of each species, were sampled during the flowering stage between 1 and 20 July 2014. Pesticide residue content was measured with the QuECHERS method in the dry matter of leaves, stalks, and inflorescence, all mixed together. Out of six herb species growing close to wheat and maize fields, pesticide residues were found in three species: A. millefolium L., E. arvense L., and P. lanceolata L. Most plants containing the residues grew 1 m away from the wheat field. Two active substances of fungicides were found: diphenylamine and tebuconazole, and one active substance of insecticides: chlorpyrifos-ethyl. Those substances are illegal to use on herbal plants. Samples of E. arvense L. and P. lanceolata L. contained two active substances each, which constituted 10% of all samples, while A. millefolium L. contained one substance, which is 6.6% of all samples.

Fluorescent analysis for bioindication of ozone on unicellular models.

Unicellular model plant systems (vegetative microspores of horsetail Equisetum arvense and pollen of six plant species Corylus avellana, Dolichothele albescens Populus balsamifera, Salix caprea, Saintpaulia ionantha, Tulipa hybridum, on which autofluorescence and fluorescence after histochemical treatment studied, have been represented as bioindicators of ozone. It has found that low doses of ozone 0.005 or 0.008 µl/l did not affect or stimulate the autofluorescence of the samples with the ability to germinate in an artificial medium. In higher ozone concentrations (0.032 µl/l) either the decrease in the intensity of the emission or changing in the position of the maxima in the fluorescence spectrum (new 515-520 nm maximum characteristic for the green-and yellow area has appeared) were observed. In dose of 0.2 µl/l, higher than above the threshold of danger to human health, autofluorescence in all samples fell down to up to zero, and there was no the ability to germinate. In this case the formation of lipofuscin-like compounds fluoresced in blue with maxima from 440 to 485 nm was observed. Stress metabolites, known as neurotransmitters biogenic amines, were found in treated cells as determined on the characteristic fluorescence at 460-480 nm in the samples after a specific histochemical reactions for catecholamines (with glyoxylic acid) or for histamine (with o-phthalic aldehyde). Increased intensity of the emission under the treatment with ozone (total doses from 0.012 to 0.032 µl/l) was associated with an increase in the concentrations of catecholamines and histamine. The fluorescent analysis on undamaged cells-possible bioindicators of ozone can be useful in ecomonitoring for earlier warning about health hazardous concentrations of this compound in the air.

[Basal bacteriosis of wheat and influence of agrotechnical methods on its spread].

Monitoring of bacterial diseases of wheat was conducted allowing for different doses of mineral fertilizers and crops predecessors. It is shown that symptoms of development of the basic disease of wheat, which is caused by Pseudomonas syringae pv. atrofaciens, varied depending on agrotechnical methods, stages of plant growth and environmental factors. Introduction of different doses of nitrogen, phosphate and potassium fertilizers, especially high ones, increases the damage of wheat by the agent of basal bacteriosis P. syringae pv. atrofaciens. Strains of this pathogen, isolated from the infected wheat plants, affect in the experiment such weeds as sow thistle, field horsetail, and couch grass.

Ontogenia de los estróbilos, desarrollo de los esporangios y esporogénesis de Equisetum giganteum (Equisetaceae) en los Andes de Colombia

Ontogeny of strobili, sporangia development and sporogenesis in Equisetum giganteum (Equisetaceae) from the Colombian Andes. Studies on the ontogeny of the strobilus, sporangium and reproductive biology of this group of ferns are scarce. Here we describe the ontogeny of the strobilus and sporangia, and the process of sporogenesis using specimens of E. giganteum from Colombia collected along the Rio Frio, Distrito de Sevilla, Piedecuesta, Santander, at 2 200m altitude. The strobili in different stages of development were fixed, dehydrated, embedded in paraffin, sectioned using a rotatory microtome and stained with the safranin O and fast green technique. Observations were made using differential interference contrast microscopy (DIC) or Nomarski microscopy, an optical microscopy illumination technique that enhances the contrast in unstained, transparent. Strobili arise and begin to develop in the apical meristems of the main axis and lateral branches, with no significant differences in the ontogeny of strobili of one or other axis. Successive processes of cell division and differentiation lead to the growth of the strobilus and the formation of sporangiophores. These are formed by the scutellum, the manubrium or pedicel-like, basal part of the sporangiophore, and initial cells of sporangium, which differentiate to form the sporangium wall, the sporocytes and the tapetum. There is not formation of a characteristic arquesporium, as sporocytes quickly undergo meiosis originating tetrads of spores. The tapetum retains its histological integrity, but subsequently the cell walls break down and form a plasmodium that invades the sporangial cavity, partially surrounding the tetrads, and then the spores. Towards the end of the sporogenesis the tapetum disintegrates leaving spores with elaters free within the sporangial cavity. Two layers finally form the sporangium wall: the sporangium wall itself, with thickened, lignified cell walls and an underlying pyknotic layer. The mature spores are chlorofilous, morphologically similar and have exospore, a thin perispore and two elaters. This study of the ontogeny of the spore-producing structures and spores is the first contribution of this type for a tropical species of the genus. Fluorescence microscopy indicates that elaters and the wall of the sporangium are autofluorescent, while other structures induced fluorescence emitted by the fluorescent dye safranin O. The results were also discussed in relation to what is known so far for other species of Equisetum, suggesting that ontogenetic processes and structure of characters sporoderm are relatively constant in Equisetum, which implies important diagnostic value in the taxonomy of the group. Rev. Biol. Trop. 59 (4): 1845-1858. Epub 2011 December 01.

Estudios sobre la ontogenia del estróbilo, los esporangios y la biología reproductiva de Equisetum son escasos, por lo tanto, para la especie E. giganteum, se estudiaron estos aspectos en especímenes recolectados a orillas del Río Frío, Santander, Colombia (2 200m). Los estróbilos en diferentes etapas de maduración fueron fijados, deshidratados, embebidos en parafina, seccionados en micrótomo rotatorio y teñidos con safranina O-fast green. Las observaciones se efectuaron mediante un microscopio óptico de alta resolución con contraste diferencial de interferencia (DIC) y microscopio de fluorescencia. Los estróbilos se inician a partir del meristemo apical, tanto en el eje principal como en los laterales, sin diferencias en el proceso de ontogenia y esporogénesis entre estróbilos de diferentes ejes. Sucesivas mitosis y diferenciación celular conducen al crecimiento del estróbilo, y a la formación de los esporangióforos peltados, formados por el manubrio, o porción basal con aspecto de pedicelo, el escutelo, o porción apical aplanada y las iniciales del esporangio, los cuales se diferenciarán para formar la pared del esporangio, los esporocitos y el tapete. No se forma arquesporio y los esporocitos experimentan meiosis para formar tétradas de esporas. El tapete mantiene la integridad histológica hasta la formación de las tétradas y en esa etapa forma un plasmodio que invade la cavidad esporangial la cual rodea parcialmente las tétradas y luego las esporas, y aparecen las cámaras plasmodiales, un término propuesto aquí para las formaciones designadas en inglés "tapetal gaps". La pared del esporangio queda reducida a dos capas celulares: una externa con engrosamientos lignificados en todas las paredes celulares y una interna picnótica. Al finalizar la esporogénesis, el tapete degenera, y las esporas, con exosporio, perisporio delgado, casi membranáceo y eláteres quedan libres en la cavidad esporangial. El esporodermo, los núcleos y nucléolos presentan fluorescencia roja, inducida por coloración con safranina O, mientras que los eláteres y las células de la pared del esporangio presentan autofluorescencia amarillo-naranja.

[Ontogeny of strobili, sporangia development and sporogenesis in Equisetum giganteum (Equisetaceae) from the Colombian Andes]. / Ontogenia de los estróbilos, desarrollo de los esporangios y esporogénesis de Equisetum giganteum (Equisetaceae) en los Andes de Colombia.

Studies on the ontogeny of the strobilus, sporangium and reproductive biology of this group of ferns are scarce. Here we describe the ontogeny of the strobilus and sporangia, and the process of sporogenesis using specimens of E. giganteum from Colombia collected along the Rio Frio, Distrito de Sevilla, Piedecuesta, Santander, at 2200m altitude. The strobili in different stages of development were fixed, dehydrated, embedded in paraffin, sectioned using a rotatory microtome and stained with the safranin O and fast green technique. Observations were made using differential interference contrast microscopy (DIC) or Nomarski microscopy, an optical microscopy illumination technique that enhances the contrast in unstained, transparent. Strobili arise and begin to develop in the apical meristems of the main axis and lateral branches, with no significant differences in the ontogeny of strobili of one or other axis. Successive processes of cell division and differentiation lead to the growth of the strobilus and the formation of sporangiophores. These are formed by the scutellum, the manubrium or pedicel-like, basal part of the sporangiophore, and initial cells of sporangium, which differentiate to form the sporangium wall, the sporocytes and the tapetum. There is not formation of a characteristic arquesporium, as sporocytes quickly undergo meiosis originating tetrads of spores. The tapetum retains its histological integrity, but subsequently the cell walls break down and form a plasmodium that invades the sporangial cavity, partially surrounding the tetrads, and then the spores. Towards the end of the sporogenesis the tapetum disintegrates leaving spores with elaters free within the sporangial cavity. Two layers finally form the sporangium wall: the sporangium wall itself, with thickened, lignified cell walls and an underlying pyknotic layer. The mature spores are chlorofilous, morphologically similar and have exospore, a thin perispore and two elaters. This study of the ontogeny of the spore-producing structures and spores is the first contribution of this type for a tropical species of the genus. Fluorescence microscopy indicates that elaters and the wall of the sporangium are autofluorescent, while other structures induced fluorescence emitted by the fluorescent dye safranin O. The results were also discussed in relation to what is known so far for other species of Equisetum, suggesting that ontogenetic processes and structure of characters sporoderm are relatively constant in Equisetum, which implies important diagnostic value in the taxonomy of the group.

[Chemical signaling in plant microspore cells].

Chemical signal transduction from the cell surface to organelles was studied in unicellular vegetative (Equisetum arvense) and generative (Hippeastrum hybridum pollen) microspores of plants. Neurotransmitters acetylcholine, dopamine, and serotonin, their agonists and antagonists, Na+, K+, and Ca2+ channel blockers, as well as forskolin and theophylline (agents increasing the intracellular level of cyclic adenosine monophosphate) were used as chemical signals. Both types of microspores exposed to neurotransmitters, their agonists, forskolin, and theophylline demonstrated growth activation, while neurotransmitter antagonists and ion channel blockers inhibited this process. No stimulating effects of neurotransmitters were observed for cells pretreated with the antagonists and ion channel blockers. Pretreatment with ion channel blockers and then by anticontractile agents (cytochalasin B or colchicine) either had no effect or increased the inhibition of microspore growth. Pathways of chemical signal transduction from the cell surface to organelles are discussed.

Tubers and rhizome fragments as propagules: competence for vegetative reproduction in Equisetum arvense.

Rhizome fragments (referred to as "fragments") and tubers of Equisetum arvense L. were cultured in order to investigate their competence with respect to vegetative reproduction. The starch concentration of the fragments was lower than that of the tubers, but the initial growth of new individuals from these fragments was superior to that from tubers obtained from the same dry mass. This superior growth was due to the large number of buds (grown from nodes) and aerial shoots on the fragments. The competence for vegetative reproduction depended on the relationship between the stored starch and the number of buds.

Use of imazapyr against Equisetum arvense on Swedish railway tracks.

Since glyphosate has been used extensively for weed control in Swedish railway tracks, common horsetail (Equisetum arvense L), previously relatively rare, has become very common. Glyphosate, although effective against most other weeds found on railway tracks, gives poor control of E. arvense, so that heavy infestation with this weed is now common. Imazapyr (applied as a 250g AE litre(-1) SL, Arsenal) has controlled E. arvense, but is known to be very mobile. Adequate control of the weed requires application of > or = 4 litres ha(-1) of imazapyr SL but environmental factors preclude the use of > 2 litres ha(-1). A suitable strategy was found to be one application of imazapyr SL at 2 litres ha(-1) in each of two successive years but best weed control was obtained by supplementing imazapyr in the first year with glyphosate 360 g AE litre(-1) SL (RoundUp Bio) at 3 litres ha(-1).

Autofluorescence of developing plant vegetative microspores studied by confocal microscopy and microspectrofluorimetry.

Phenomenon of autofluorescence from vegetative microspores of spore-breding plant Equisetum arvense has been studied by methods of laser-scanning confocal microscopy (LSCM) and microspectrofluorimetry during the development of the cells. The microspores have demonstrated a difference between structures: blue-fluorescing cover and red-fluorescing chloroplasts. The fluorescence spectra of the studied cells was also measured by original microspectrofluorimeter. The character of the spectra and the color of fluorescence was changed during the microspores germination. The red fluorescence of the microspores was, mainly, due to the presence of chlorophyll and azulenes. The unicellular microspores may be recommended as natural probes of cellular viability and development.

Modelling primary and secondary growth processes in plants: a summary of the methodology and new data from an early lignophyte.

A mathematical method, based on polar coordinates that allow modelling of primary and secondary growth processes in stems of extant and fossil plants, is summarized and its potential is discussed in comparison with numerical methods using digitizing tablets or electronic image analysing systems. As an example, the modelling of tissue distribution in the internode of an extant sphenopsid (Equisetum hyemale) is presented. In the second half of the paper we present new data of a functional analysis of stem structure and biomechanics of the early lignophyte Tetraxylopteris schmidtii (Middle Devonian) using the polar coordinate method for modelling the tissue distribution in stems of different ontogenetic age. Calculations of the mechanical properties of the stems, based on the modelling of the tissue arrangement, indicate that there is no increase in structural bending modulus throughout the entire development of the plant. The oldest ontogenetic stage has a significantly smaller bending elastic modulus than the intermediate ontogenetic stage, a 'mechanical signal', which is not consistent with a self-supporting growth form. These results, and the ontogenetic variations of the contributions of different stem tissues to the flexural stiffness of the entire stem, are discussed in the evolutionary context of cambial secondary growth.

[Autofluorescence of intact Equisetum arvense L. spores during their development]. / Avtofluorestsentsiia intaktnykh spor khvoshcha Equisetum arvense L. v protsesse razvitiia.

The autofluorescence of horsetail Equisetum arvense spores excited with UV-light of 360-380 nm was studied by microspectrofluorimetry during their development from an individual cell to the formation of a multicellular thallus with the generative organs. The investigation involved the registration of the fluorescence spectra of individual intact developing cells and the measurement of the ratio of cell fluorescence intensities in the blue and red regions of the spectrum. Dry blue-fluorescing microspores showed the maxima at 460 and 530 nm and a small maximum at 680 nm. Thirty minutes after moistening in water, red-fluorescing cells arose among blue-fluorescing microspores, indicating the onset of development. Red fluorescence with a maximum at 680 nm enhanced as cells put off their cover, which brightly fluoresced in the blue region of the spectrum with the main maximum at 460 nm. By estimating the ratio of autofluorescence intensities in the blue region of the spectrum to red lightening of microspores at the first stages of development up to 24 h (in particular, their first division, the formation of nonfluorescencing rhizoid, etc.), nonviable (only blue-lightening) cells were distinguished from viable cells, in which red fluorescence began to prevail. After 25-40 days of development, the gametophyte fluorescing mainly at 680 nm formed male organs, antheridia, with blue-green-fluorescing spermatozoids. Then female generative organs archegonia with the egg cell appeared, which fluoresced blue, whereas the surrounding cells fluoresced red. It was supposed that the lightening in the blue and green regions of the spectrum is due to the presence of phenols, terpenoids, and azulenes, whereas the emission in the red region is associated with the presence of chlorophyll and azulenes. The observation of autofluorescence makes it possible to easily distinguish generative cells without additional staining.