Insights into the chemical composition of Equisetum hyemale by high resolution Raman imaging.

Equisetaceae has been of research interest for decades, as it is one of the oldest living plant families, and also due to its high accumulation of silica up to 25% dry wt. Aspects of silica deposition, its association with other biomolecules, as well as the chemical composition of the outer strengthening tissue still remain unclear. These questions were addressed by using high resolution (<1 microm) Confocal Raman microscopy. Two-dimensional spectral maps were acquired on cross sections of Equisetum hyemale and Raman images calculated by integrating over the intensity of characteristic spectral regions. This enabled direct visualization of differences in chemical composition and extraction of average spectra from defined regions for detailed analyses, including principal component analysis (PCA) and basis analysis (partial least square fit based on model spectra). Accumulation of silica was imaged in the knobs and in a thin layer below the cuticula. In the spectrum extracted from the knob region as main contributions, a broad band below 500 cm(-1) attributed to amorphous silica, and a band at 976 cm(-1) assigned to silanol groups, were found. From this, we concluded that these protrusions were almost pure amorphous, hydrated silica. No silanol group vibration was detected in the silicified epidermal layer below and association with pectin and hemicelluloses indicated. Pectin and hemicelluloses (glucomannan) were found in high levels in the epidermal layer and in a clearly distinguished outer part of the hypodermal sterome fibers. The inner part of the two-layered cells revealed as almost pure cellulose, oriented parallel along the fiber.

[Contractile proteins in chemical signal transduction in plant microspores].

Involvement of contractile components in chemical signal transduction from the cell surface to the organelles was studied using unicellular systems. Neurotransmitters dopamine and serotonin as well as active forms of oxygen hydrogen peroxide and tert-butyl peroxide were used as chemical signals. Experiments were carried out on vegetative microspores of field horsetail Equisetum arvense and generative microspores (pollen) of amaryllis Hippeastrum hybridum treated with cytochalasin B (an inhibitor of actin polymerization in microfilaments), colchicine, and vinblastine (inhibitors of tubulin polymerization in microtubules). Both types of thus treated microspores demonstrated suppressed development, particularly, for cytochalasin B treatment. At the same time, an increased typical blue fluorescence of certain cell regions (along the cell wall and around nuclei and chloroplasts) where the corresponding contractile proteins could reside was observed. In contrast to anticontractile agents, dopamine, serotonin B, and the peroxides stimulated microspore germination. Microspore pretreatment with cytochalasin B and colchicine followed by the treatment with serotonin, dopamine, or the peroxides decreased the germination rate. Involvement of actin and tubulin in chemical signal transduction from the cell surface to the nucleus is proposed.

[Reactive oxygen forms and luminescence of intact microspore cells]. / Aktivnye formy kisloroda i liuminestsentsiia intaktnykh kletok mikrospor.

The participation of reactive oxygen species (ROS) in luminescence (chemiluminescence and autofluorescence induced by ultraviolet light of 360-380 nm) was analyzed. Microspores, the pollen (male gametophyte) of Hippeastrum hybridum, Philadelphus grandiflorus, and Betula verrucosa and vegetative microspores of the spore-breeding plant Equisetum arvense served as models. It was found that the addition of the chemiluminescent probe lucigenin, which luminesces in the presence of superoxide anionradicals, leads to intensive chemiluminescence of microspores. No emission was observed in the absence of lucigenin and in the presence of the dye luminol as a chemiluminescent probe. The emission decreased significantly if superoxide dismutase, an enzyme of the superoxide anionradical dismutation during which this radical disappeared, was added before the dye addition. The autofluorescence intensity of microspores decreased in the presence of both superoxide dismutase and peroxidase, an enzyme destroying hydrogen peroxide and organic peroxides. The most significant effect was noted after the addition of peroxidase, which indicates a greater contribution of peroxides to this type of emission. The fumigation with ozone, which increases the amount of ROS on the cell surface, enhanced the intensity of the chemiluminescence of microspores with lucigenin, but decreased the intensity of the autofluorescence of microspores. Exogenous peroxides (hydrogen peroxide and tert-butylhydroperoxide) stimulated the autofluorescence of pollen and vegetative spores in a concentration-dependent manner. It was shown that the formation of ROS contributes to the luminescence of plant microspores, which reflects their functional state.

Maternal inheritance of chloroplasts in the horsetail Equisetum variegatum (Schleich.).

Reliable data concerning the transmission of chloroplasts in the Pteridophyta are needed both for phylogenies based on chloroplast DNA (cpDNA) sequences and in order to study the evolution of this trait in conjunction with the evolution of the life cycle and the sexual reproduction of land plants. For the first time, this paper describes organelle transmission in the division Sphenophyta, represented by the extant genus Equisetum. By following the fate of polymorphic cpDNA during three intraspecific reciprocal crosses we found no trace of paternal transmission in Equisetum variegatum. The seemingly strict maternal transmission of cpDNA in this species suggests that uniparental chloroplast inheritance preceded the evolution of heterospory in the seed-plant lineage.