Institute of Botany of the ASCR
Recent publications
Pharmaceutical products are some of the most serious emergent pollutants in the environment, especially nowadays of the COVID-19 pandemic. In this study, nanogold-composite was prepared, and its catalytic activity for paracetamol degradation was investigated. Moreover, for the first time, recycled waste diatomite earth (WDE) from beer filtration was used for reproducible gold nanoparticle (Au NPs) preparation. We studied Au NPs by various psychical-chemical and analytical methods. Transmission and scanning electron microscopy were used for nanogold-composite morphology, size and shape characterization. Total element concentrations were determined using inductively coupled plasma mass and X-ray fluorescence spectrometry. X-ray powder diffraction analysis was used for crystal structure characterization of samples. Fourier transform infrared spectrometer was used to study the chemical changes before and after Au NP formation. The results revealed that the WDE served as both a reducing and a stabilizing agent for crystalline spherical 30 nm Au NPs as well as acting as a direct support matrix. The kinetics of paracetamol degradation was studied by high-performance liquid chromatography with a photodiode array detector. The conversion of paracetamol was 62% and 67% after 72 h in the absence or presence of light irradiation, respectively, with 0.0126 h⁻¹ and 0.0148 h⁻¹ reaction rate constants. The presented study demonstrates the successful use of waste material from the food industry for nanogold-composite preparation and its application as a promising catalyst in paracetamol removal. Graphical abstract
Solubility of growth regulators is essential for their use in agriculture. Four new cytokinin salts─6-benzylaminopurine mesylate (1), 6-(2-hydroxybenzylamino)purine mesylate (2), 6-(3-hydroxybenzylamino)purine mesylate (3), and 6-(3-methoxybenzylamino)purine mesylate (4)─were synthesized, and their crystal structures were determined to clarify structural influence on water solubility. The mesylates were several orders of magnitude more water-soluble than the parent CKs. The new salts significantly reduced chlorophyll degradation and impairment of photosystem II functionality in barley leaf segments undergoing artificial senescence and had pronounced effects on the leaves' endogenous CK pools, maintaining high concentrations of functional metabolites for several days, unlike canonical CKs. A foliar treatment with 1 and 3 increased the harvest yield of spring barley by up to 8% when compared to treatment with the parent CKs while also increasing the number of productive tillers. This effect was attributed to the higher bioavailability of the mesylate salts and the avoidance of dimethyl sulfoxide exposure.
ARP2/3 is a heteroheptameric protein complex evolutionary conserved in all eukaryotic organisms. Its conserved role is based on the induction of actin polymerization at the interface between membranes and the cytoplasm. Plant ARP2/3 has been reported to participate in actin reorganization at the plasma membrane during polarized growth of trichomes and at the plasma membrane-endoplasmic reticulum contact sites. We demonstrate here that individual plant subunits of ARP2/3 fused to fluorescent proteins form motile dot-like structures in the cytoplasm that are associated with plant peroxisomes. ARP2/3 dot structure is found at the peroxisome periphery and contains assembled ARP2/3 complex and WAVE/SCAR complex subunit NAP1. This dot occasionally colocalizes with the autophagosome, and under conditions that affect the autophagy, colocalization between ARP2/3 and the autophagosome increases. ARP2/3 subunits co-immunoprecipitate with ATG8f marker. Since mutants lacking functional ARP2/3 complex have more peroxisomes than WT, we link the ARP2/3 complex on peroxisomes to the process of peroxisome degradation by autophagy called pexophagy. Additionally, several other peroxisomal proteins colocalize with ARP2/3 dot on plant peroxisomes. Our results suggest a specific role of ARP2/3 and actin in the peroxisome periphery, presumably in membrane remodelling. We hypothesize that this role of ARP2/3 aids processes at the peroxisome periphery such as peroxisome degradation through autophagy or regulation of peroxisomal proteins localization or function.
A wide range of methods can be used for nature-inspired metallic nanoparticle (NP) synthesis. These syntheses, however, are ongoing in the presence of diverse mixtures of different chemical compounds, and all or only a few of these contribute to resultant particle properties. Herein, the linden (Tilia sp.) inflorescence leachate and pure citric and protocatechuic acids were chosen for Ag-AgCl nanoparticle (NP) synthesis, and the resultant particles were then compared. We focused on the following four issues: (1) preparation of Ag-AgCl NPs using the Tilia sp.-based phytosynthetic protocol, (2) analytical determination of the common phenolic, nonphenolic, and inorganic profiles of three Tilia sp. types from different harvesting locations, (3) preparation of Ag-AgCl NPs using a mixture of citric and protocatechuic acids based on chromatographic evaluation, and (4) comparison of Tilia-based and organic acid-based syntheses. Our research confirms that the Tilia organic and inorganic profiles in biomasses are influenced by the harvesting location, and the three sites influenced both the morphology and final NP size. Our processing method was uniform, and this enabled great Ag-AgCl NP reproducibility for each specific biomass. We were then able to prove that the simplified organic acid-based synthesis produced even smaller NPs than Tilia-based synthesis. These findings provide better understanding of the significant influence on NP final properties resulting from other organic acids contained in the linden.
Chloroplast-localized adenosine-5'-phosphosulphate reductase (APR) generates sulfite and plays a pivotal role in sulfate reduction to cysteine. The peroxisome-localized sulfite oxidase (SO), oxidizes excess sulfite to sulfate. Wild-type (WT), SO RNA-interference (SO Ri) and SO overexpression (SO OE) Arabidopsis mutants were infiltrated with sulfite. In SO Ri plants, water loss was increased due to enhancement of stomatal aperture compared to WT leaves, whereas in SO OE plants, stomatal aperture was smaller than that of the WT plants, and hence water loss was lower. Sulfite application also limited sulfate and ABA-induced stomatal closure in WT and SO Ri. The increases in APR activity in response to sulfite infiltration into WT and SO Ri leaves resulted in an increase in sulfite beyond the level of the applied sulfite, indicating that APR has an important role in sulfite-induced increases in stomatal aperture. Notably, sulfite-induced H2O2 generation by NADPH oxidase, led to enhanced APR expression and sulfite production. Suppression of APR by inhibiting NADPH oxidase and glutathione reductase2 (GR2) by diphenyleneiodonium, or mutation in APR2 or GR2, resulted in decrease in sulfite production and stomatal aperture size, further supporting the role of APR in stomatal aperture size. The importance of APR and SO in the set-up of sulfite level in leaves, and the significance of sulfite level in water loss were further demonstrated during fast and harsh drought stress in root-detached WT, gr2 and SO modified plants. The role of SO in sulfite homeostasis in relation to water consumption was shown in well-watered plants.
The chapter illustrates the gradual way in which the molecule of the active aromatic cytokinin, meta-topolin, was created. The historical development of the synthetic method from the first attempts to prepare aromatic cytokinins to professional organic synthesis is described here. The chapter also covers the preparation of second-generation aromatic derivatives of meta-topolin, e.g. C2- and/or N9-derivatives. The added value of such cytokinin derivatives over the original meta-topolin molecule is highlighted.
In temperate perennial grasslands, the recruitment/regeneration of aboveground vegetation predominantly relies on belowground bud bank. Thus, understanding how belowground bud bank density and composition respond to global changes is essential to explain and predict plant community dynamics and ecosystem functions under global change context. The belowground bud bank and aboveground vegetation under the simulated precipitation changes and nitrogen deposition (by watering and N addition) were investigated in the temperate semiarid steppe of Inner Mongolia, China. N addition decreased total bud density but facilitated aboveground productivity, however, watering itself and its combination with N addition had little influence on total bud density. Different bud bank types showed specific responses to watering and N addition, especially, buds of grasses and forbs responded in an opposite way. Overall, shoot abundance were positively related to bud density, and showed similar responses with those of bud banks, especially for forbs, which are more sensitive to global changes. Our results imply that the changes in belowground bud bank might affect subsequent responses of plant communities to precipitation change and/or nitrogen deposition under future global change scenarios.
The interactions of fungal guilds have recently been proposed as drivers of organic matter transformation in forest soils. We conducted a pot experiment with Norway spruce seedlings planted in spruce needle litter inoculated with several fungal strains belonging to different ecological guilds (saprotrophic, mycorrhizal, and root endophytic) to assess how the fungi and their interactions affect the transformation of humic substances (HS) and phosphorus (P) in the litter. Several methods for the characterization of P forms and HS were employed, including ³¹P NMR, UV–Vis and FTIR spectroscopy. Our results show that fungal interactions influence not only the flow of P in decaying (plant) litter but also the transformation of the soil organic matter itself. Pots with saprotrophic Gymnopus androsaceus generally retained more P and prevented the accumulation of phosphonates caused by mycorrhizal Hyaloscypha finlandica, highlighting the strong competitive ability of the former species. The increased mineralization of P caused by G. androsaceus was not observed in the combined treatments, suggesting that other present fungi took up part of the inorganic P. The tested fungi did not affect the amount of HS produced but changed the characteristics of the HS. Mycorrhizal H. finlandica and root endophytic Phialocephala fortinii increased the relative proportion of carboxylic moieties in the HS regardless of the presence or absence of G. androsaceus, probably via the production and incorporation of melanins. The UV–Vis absorbance characteristics of the HS were significantly influenced by fungal interactions. Mycorrhizal H. finlandica and Hebeloma bryogenes retarded humification, as determined by the A4/6 ratio. We attribute the similar shift observed in Serpula himantoides to the partial oxidative degradation of HS. Our study shows that fungal root endophytes can significantly contribute to litter transformation along with mycorrhizal and saprotrophic fungi. The extent and patterns of the transformation seem to be species-dependent in all studied fungal groups.
Cytokinins and their sugar or non-sugar conjugates are very active growth-promoting factors in plants, although they occur at very low concentrations. These compounds have been identified in numerous plant species. This review predominantly focuses on 9-substituted adenine-based cytokinin conjugates, both artificial and endogenous, sugar and non-sugar, and their roles in plants. Acquired information about their biological activities, interconversions, and metabolism improves understanding of their mechanisms of action and functions in planta. Although a number of 9-substituted cytokinins occur endogenously, many have also been prepared in laboratories to facilitate the clarification of their physiological roles and the determination of their biological properties. Here, we chart advances in knowledge of 9-substituted cytokinin conjugates from their discovery to current understanding and reciprocal interactions between biological properties and associated structural motifs. Current organic chemistry enables preparation of derivatives with better biological properties, such as improved anti-senescence, strong cell division stimulation, shoot forming, or more persistent stress tolerance compared to endogenous or canonical cytokinins. Many artificial cytokinin conjugates stimulate higher mass production than naturally occurring cytokinins, improve rooting, or simply have high stability or bioavailability. Thus, knowledge of the biosynthesis, metabolism, and activity of 9-substituted cytokinins in various plant species extends the scope for exploiting both natural and artificially prepared cytokinins in plant biotechnology, tissue culture, and agriculture.
Retrotransposable elements are widely distributed and diverse in eukaryotes. Their copy number increases through reverse-transcription-mediated propagation, while they can be lost through recombinational processes, generating genomic rearrangements. We previously identified extensive structurally uniform retrotransposon groups in which no member contains the gag, pol, or env internal domains. Because of the lack of protein-coding capacity, these groups are non-autonomous in replication, even if transcriptionally active. The Cassandra element belongs to the non-autonomous group called terminal-repeat retrotransposons in miniature (TRIM). It carries 5S RNA sequences with conserved RNA polymerase (pol) III promoters and terminators in its long terminal repeats (LTRs). Here, we identified multiple extended tandem arrays of Cassandra retrotransposons within different plant species, including ferns. At least 12 copies of repeated LTRs (as the tandem unit) and internal domain (as a spacer), giving a pattern that resembles the cellular 5S rRNA genes, were identified. A cytogenetic analysis revealed the specific chromosomal pattern of the Cassandra retrotransposon with prominent clustering at and around 5S rDNA loci. The secondary structure of the Cassandra retroelement RNA is predicted to form super-loops, in which the two LTRs are complementary to each other and can initiate local recombination, leading to the tandem arrays of Cassandra elements. The array structures are conserved for Cassandra retroelements of different species. We speculate that recombination events similar to those of 5S rRNA genes may explain the wide variation in Cassandra copy number. Likewise, the organization of 5S rRNA gene sequences is very variable in flowering plants; part of what is taken for 5S gene copy variation may be variation in Cassandra number. The role of the Cassandra 5S sequences remains to be established.
Plant survival depends on vascular tissues, which originate in a self‐organizing manner as strands of cells co‐directionally transporting the plant hormone auxin. The latter phenomenon (a.k.a. auxin canalization) is classically hypothesized to be regulated by auxin itself via the effect of this hormone on the polarity of its own intercellular transport. Correlative observations supported this concept, but molecular insights remain limited. In the current study, we established an experimental system based on the model Arabidopsis thaliana that exhibits auxin transport channels and vasculature strands formation in response to local auxin application. Our methodology permits the genetic analysis of auxin canalization under controllable experimental conditions. By utilizing this opportunity, we confirmed the dependence of auxin canalization on a PIN‐dependent auxin transport and nuclear, TIR1/AFB‐mediated auxin signaling. We also show that leaf venation and auxin‐mediated PIN repolarization in the root require TIR1/AFB signaling. Further studies based on this experimental system are likely to yield better understanding of mechanisms underlying auxin transport polarization in other developmental contexts.
Cytokinins (CKs) and their metabolites and derivatives are essential for cell division, plant growth regulation and development. They are typically found at minute concentrations in plant tissues containing very complicated biological matrices. Therefore, defined standards labelled with stable isotopes are required for precise metabolic profiling and quantification of CKs, as well as in vivo elucidation of CK biosynthesis in various plant species. In this work, 11 [¹⁵N]-labelled C6-purine derivatives were prepared, among them 5 aromatic (4, 5, 6, 7, 8) and 3 isoprenoid (9, 10, 11) CKs. Compared to current methods, optimized syntheses of 6-amino-9H-[¹⁵N5]-purine (adenine) and 6-chloro-9H-[¹⁵N4]-purine (6-chloropurine) were performed to achieve more effective, selective and generally easier approaches. The chemical identity and purity of prepared compounds were confirmed by physico-chemical analyses (TLC; HRMS; HPLC–MS; ¹H, ¹³C, ¹⁵N NMR). The presented approach is applicable for the synthesis of any other desired [¹⁵N4]-labelled C6-substituted purine derivatives.
Aerial dispersal in the colonization of bare ground by lichens in the polar regions remains poorly understood. Potential colonists may arrive continually, although extreme abiotic conditions limit their viability. We investigated the vegetative dispersal of Antarctic macrolichens along a successional gradient (from 8.6–7.0 ka BP up to present) after glacial retreat on James Ross Island, in the Antarctic Peninsula region. We collected lichen fragments by means of sticky traps glued on the ground and exposed for 1 year. Foliose or fruticose growth types were the most frequently recorded species (namely Usnea spp. and Leptogium puberulum) together with widely distributed fungi mycelia, while crustose lichens were not found. Although these two lichen species are also locally the most common, their frequency of occurrence in the traps was largely unrelated to local dominance, indicating long-distance dispersal. On the other hand, the dispersed community assembly was related to overall lichen cover and ground physical structure (clast size). There was a gradient of species occurrence frequency increasing with maximal clast size and distance from the glacier front. These results imply that there is no dispersal limitation (at least for certain lichen species) in the colonization of newly deglaciated substrates at the regional scale on James Ross Island. However, lichen establishment is rather rare, and growth of a lichen community is therefore a long-term process.
In this study, we report the synthesis, antibacterial and anticancer evaluation of 38 novel phenanthridines that were designed as analogs of the benzo[c]phenanthridine alkaloids. The prepared phenanthridines differ from the benzo[c]phenanthridines in the absence of a benzene A-ring. All novel compounds were prepared from 6-bromo-2-hydroxy-3-methoxybenzaldehyde in several synthetic steps through reduction of Schiff bases and accomplished by radical cyclization. Twelve derivatives showed high antibacterial activity against Bacillus subtilis, Micrococcus luteus and/or Mycobacterium vaccae at single digit micromolar concentrations. Some compounds also displayed cytotoxicity against the K-562 and MCF-7 cancer cell lines at as low as single digit micromolar concentrations and were more potent than chelerythrine and sanguinarine. The active compounds caused cell-cycle arrest in cancer cells, increased levels of p53 protein and caused apoptosis-specific fragmentation of PARP-1. Biological activity was connected especially with the presence of the N-methyl quaternary nitrogen and 7-benzyloxy substitution (compounds 7i, 7j, 7k, and 7l) of phenanthridine.
Agricultural intensification over the last 40 years has increased cereal yields, but there is very limited information on the effects of intensification practices (e.g. non-diverse rotations, mineral NPK fertiliser and pesticides) on crop health and quality. Results from the study reported here suggest that the use of mineral NPK fertilisers reduces phenolic acid and flavonoid concentrations in leaves, and increases the susceptibility of wheat to lodging and powdery mildew, when compared to composted FYM inputs. In contrast, the use of herbicides, fungicides and growth regulators reduces lodging and foliar disease severity, but had no effect on phenolic acid and flavonoid concentrations. The use of composted FYM inputs also resulted in a significant grain yield reduction and not substantially reduced the severity of opportunistic pathogens such as Septoria, which remain a major yield limiting factor unless fungicides are used and/or more Septoria resistant varieties become available.
Reproduction success in angiosperm plants depends on robust pollen tube growth through the female pistil tissues to ensure successful fertilization. Accordingly, there is an apparent evolutionary trend to accumulate significant reserves during pollen maturation, including a population of stored mRNAs, that are later utilized for a massive translation of various proteins in growing pollen tubes. Here, we performed a thorough transcriptomic and proteomic analysis of stored and translated transcripts in three subcellular compartments of tobacco (Nicotiana tabacum) - long-term storage EDTA/puromycine-resistant particles (EPPs), translating polysomes, and free ribonuclear particles - throughout tobacco pollen development and in in vitro growing pollen tubes. We demonstrated that the composition of the aforementioned complexes is not rigid and that numerous transcripts were re-distributed among these complexes during pollen development, which may represent an important mechanism of translational regulation. Therefore, we defined the pollen sequestrome as a distinct and highly dynamic compartment for the storage of stable, translationally-repressed transcripts and demonstrated its dynamics. We propose that EPP complexes represent aggregated non-translating monosomes as the primary mediators of mRNA sequestration. Such organization is extremely useful in fast tip-growing pollen tubes, where rapid and orchestrated protein synthesis must take place in specific regions.
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68 members
Michael Bartos
  • Department of Functional Ecology
Ladislava Paštová
  • Laboratory of Molecular Cytogenetics and Karyology
Vlasta Jankovská
  • Department of Vegetation Ecology
Péter Szabó
  • Department of Vegetation Ecology
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Miroslav Vosátka
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www.ibot.cas.cz