Papers by Marina Dermastia
Environmental Pollution, 2008
The increase of total antioxidative potential at low cadmium concentration is one of the mechanis... more The increase of total antioxidative potential at low cadmium concentration is one of the mechanisms that helps duckweed to cope with cadmium-induced oxidative stress.
Environmental Science and Pollution Research, 2007
Goal, Scope and Background Elevated concentrations of copper in the environment result in accumul... more Goal, Scope and Background Elevated concentrations of copper in the environment result in accumulation of the metal in plants and cause an increase in reactive oxidative species (ROS). The first response to elevated amounts of ROS is increased levels of enzymatic and non-enzymatic antioxidants that reduce oxidative stress. The aim of our study was to evaluate the early stages of antioxidative responses to the low copper concentrations usually present in moderately polluted environments. In addition, some other parameters were examined to evaluate the effect of copper on plants. Methods Duckweed (Lemna minor L.) was exposed to different concentrations of copper sulphate for up to 24 hours. Glutathione concentration and enzymatic activities of catalase, guaiacol peroxidase and glutathione reductase were measured spectrophotometrically. Additionally, delayed and prompt chlorophyll fluorescence was measured by luminometry and fluorometry, respectively. The accumulation of copper in plants exposed for 24 hours to various concentrations of copper sulphate was measured by flame atomic absorption spectrophotometry. Results The treatment of plants with copper sulphate resulted in an immediate decrease of the glutathione pool, which was replenished after 24 hours at CuSO4 concentrations lower than 2 μM. Higher CuSO4 concentrations caused a decrease of reduced glutathione. The responses of the antioxidant enzymes glutathione reductase, guaiacol peroxidase and catalase to CuSO4 differed during the first six hours of exposure, but their enzyme activities all increased after 24 hours of exposure. All these enzymes displayed biphasic activity curves with maximum values between 0.5 μM and 1 μM CuSO4. The response of guaiacol peroxidase was the most pronounced and statistically significantly specific and that of catalase the least. Delayed chlorophyll fluorescence decreased after exposure to 1 μM CuSO4, but no significant effect on maximum quantum yield of photosystem II (Fv/Fm) was observed. L. minor accumulated relatively high concentrations of copper. The accumulation rate was higher at lower concentrations of copper in the test medium (up to 2 μM CuSO4) than at concentrations above 2 μM CuSO4. Discussion One of the most pronounced antioxidative responses to copper exposure was modified levels of oxidized and reduced forms of glutathione. The decrease of the glutathione pool is most probably coupled with induced production of phytochelatins. Antioxidative enzymes showed the biphasic enzyme activity characteristic of stress response. Guaiacol peroxidase exhibited the greatest significant increase of activity, even at higher CuSO4 concentrations at which the activity of catalase and glutathione reductase dropped. The intensity of delayed chlorophyll fluorescence decreased, indicating reduced photosynthesis of plants under stress. All the measured parameters showed that plants respond to even low copper concentrations very soon after exposure. The accumulation rate of copper in duckweed tissues indicates that L. minor is an accumulator species. Conclusions The synchronized and prompt inducibility of antioxidants indicates their involvement in a general plant defence strategy for coping with metal-induced oxidative stress. Glutathione concentration and guaiacol peroxidase activity were found to be the most sensitive of the early indicators of exposure to copper concentrations present in polluted water bodies. Recommendation and Perspectives The experimental design of the present study allowed us to compare the sensitivity of various methods and parameters for detecting plant responses to heavy metal-induced oxidative stress. The level of glutathione and the enzyme activities of guaiacol peroxidase and glutathione reductase could be used as a rapidly determined early warning system in toxicity studies.
Fems Microbiology Letters, 1991
A DNA mediated transformation system has been developed for the filamentous fungus Cochliobolus l... more A DNA mediated transformation system has been developed for the filamentous fungus Cochliobolus lunatus. Transformants were obtained by using plasmid pAN 7–1 carrying the Escherichia coli hygromycin B phosphotransferase gene (hph) fused to an Aspergillus nidulans promoter. The integration of plasmid pAN 7–1 into the fungal genome altered the ability of this microorganism to transform progesterone.
Current Microbiology, 1991
The phenomena following the transformation of the fungusCochliobolus lunatus by plasmid-encoded H... more The phenomena following the transformation of the fungusCochliobolus lunatus by plasmid-encoded HmB resistance were investigated. All of the 16 tested transformants had markedly altered morphology. Unlike the untransformed fungus, the transformants produced both conidia and arthrospores, did not excrete slime, lost their purple color, and had an altered progesterone-bioconverting pathway.
Fems Microbiology Letters, 1991
Physiological and Molecular Plant Pathology, 1996
Plants of the susceptible potato cultivar Igor systemically infected with potato virus Y NTN were... more Plants of the susceptible potato cultivar Igor systemically infected with potato virus Y NTN were grown in tissue culture. The symptoms of infection which are strongly expressed in soil-grown plants were suppressed and plantlets exhibited an enhanced tolerance to PVY NTN . Determination of nine endogenous cytokinins in virus free and infected plantlets revealed an increase in total cytokinin level in systemically infected potatoes. This elevation was due mainly to a seven-fold increase in levels of zeatin riboside and an 18-fold increase in the concentration of the biologically inactive iso-pentenyl adenine-9-glucoside. Although the amount of 9-glucosilation of iso-pentenyl adenine was significant, total cytokinin deactivation did not exceed 23 %. The possible role of the observed changes in cytokinin concentrations in the control of symptom development and resistance is discussed.
Ecological Applications, 2009
In eukaryotes, nuclear genome sizes vary by more than five orders of magnitude. This variation is... more In eukaryotes, nuclear genome sizes vary by more than five orders of magnitude. This variation is not related to organismal complexity, and its origin and biological significance are still disputed. One of the open questions is whether genome size has an adaptive role. We tested the hypothesis that genome size has selective significance, using five grassland communities occurring on a gradient of metal pollution of the soil as a model. We detected a negative correlation between the concentration of contaminating metals in the soil and the number of vascular plant species. Analysis of genome sizes of 70 herbaceous dicot perennial species occurring on the investigated plots revealed a negative correlation between the concentration of contaminating metals in the soil and the proportion of species with large genomes in plant communities. Consistent with the hypothesis, these results show that species with large genomes are at selective disadvantage in extreme environmental conditions.
International Journal of Plant Sciences, 2006
Osmotin-like proteins from the fifth class of pathogenesis-related proteins , including linusitin... more Osmotin-like proteins from the fifth class of pathogenesis-related proteins , including linusitin that we isolated from flax seeds, have been characterized in many plant species. A cDNA library has been constructed from flax (Linum usitatissimum L.) seedlings to analyze the osmotin-like gene family from flax. A cDNA LIN1 was isolated from the library and found to exhibit significant similarities to genes encoding osmotin-like proteins and thaumatin from Thaumatococcus daniellii. The deduced LIN1 protein contains all 16 cysteine residues that are conserved in all PR-5 proteins as well as other residues important for antifungal activity. The LIN1 cDNA encodes a preprotein, which is subsequently processed into the mature protein by removal of an N-terminal signal peptide. Southern blot analysis showed that the LIN1 gene family is encoded by few copies in the flax genome. The gene encoding LIN1 is intronless and developmentally regulated, and transcripts accumulate in an organ-specific manner in healthy flax seedlings. The LIN1 mRNA was constitutively expressed, predominantly in root tissue. The comparison of N-terminus sequences from linusitin-like protein (LIN1) and previously isolated linusitin confirmed differences in amino acid composition and demonstrated the occurrence of at least two osmotin-like proteins in flax.
Botanica Helvetica, 2006
Strgulc Krajšek S., Dermastia M. and Jogan N. 2006. Determination key for Central European Epilob... more Strgulc Krajšek S., Dermastia M. and Jogan N. 2006. Determination key for Central European Epilobium species based on trichome morphology. Bot. Helv. 116: 169 -178.
Plant Biology, 2003
Abstract: One of the ways that plants respond to biotic and/or abiotic stress factors is the accu... more Abstract: One of the ways that plants respond to biotic and/or abiotic stress factors is the accumulation of pathogenesis-related proteins of class 5 (PR-5), which are evolutionary conserved in the plant kingdom. Within the PR-5 family, a distinct subgroup of osmotin and closely related proteins has been characterized. In contrast to the extracellular forms of PR-5 proteins, osmotins presumably accumulate in the vacuole of the cell. They contain a C-terminal propeptide that is considered to be a determinant for vacuolar targeting. The comparison of the three-dimensional structure of tobacco PR-5 d with the sequences of some osmotins showed that the proteins consist of three conserved domains, with the acidic cleft between domains I and II. Besides the constitutive species and tissue-specific presence, the osmotins are also induced by several abiotic and biotic stresses. Among them, fungal infections can elicit osmotin gene expression, and most known proteins from the family have antifungal activity in in vitro assays. In agreement with the osmotin structure and data on the activity of similar proteins, a two-step mechanism, which involves reaction of osmotins with the fungal wall and the permeabilization of fungal membranes, is discussed.
Journal of Plant Growth Regulation, 1996
Stem node culture of the potato (Solanum tuberosum) cv. Sante was used to examine the phenotypica... more Stem node culture of the potato (Solanum tuberosum) cv. Sante was used to examine the phenotypical alterations due to different levels of endogenous cytokinins. The altered phenotype, which dramatically deviates from the control phenotype, was induced after treatment of plantlets with 1 μm jasmonic acid. Plantlets grown on the medium supplemented with jasmonic acid were taller, with well developed root systems, expanded leaves, thickened stems, and they showed hyperhydric symptoms. Their cytokinin content was about half that of the control plantlets. Morphologic characteristics corresponding to transgenic plants that overproduce cytokinins, including release of axillary buds and inhibited rooting, correlated with the high cytokinin levels in control plants.
Physiologia Plantarum, 1994
M. 1994. Increased level of cytokinin ribosides in jasmonic acid-treated potato (Solanum tuberosu... more M. 1994. Increased level of cytokinin ribosides in jasmonic acid-treated potato (Solanum tuberosum) stem node cultures. -Physiol. Planl. 92: 241-246.
Canadian Journal of Microbiology, 2007
The germination of surface-sterilized maize kernels under aseptic conditions proved to be a suita... more The germination of surface-sterilized maize kernels under aseptic conditions proved to be a suitable method for isolation of kernel-associated bacterial endophytes. Bacterial strains identified by partial 16S rRNA gene sequencing as Pantoea sp., Microbacterium sp., Frigoribacterium sp., Bacillus sp., Paenibacillus sp., and Sphingomonas sp. were isolated from kernels of 4 different maize cultivars. Genus Pantoea was associated with a specific maize cultivar. The kernels of this cultivar were often overgrown with the fungus Lecanicillium aphanocladii; however, those exhibiting Pantoea growth were never colonized with it. Furthermore, the isolated bacterium strain inhibited fungal growth in vitro.
Aquatic Botany, 2003
Genome size (C-value) was measured in four species of Adriatic seagrasses with interphase-peak DN... more Genome size (C-value) was measured in four species of Adriatic seagrasses with interphase-peak DNA image cytometry. The estimated 2C-value was 1.5 pg DNA for Zostera noltii (2n = 12), 1.2 pg for Zostera marina (2n = 12), 1.1 pg for Cymodocea nodosa (2n = 28) and 6.2 pg for Posidonia oceanica, using Pisum sativum (2C-value = 8.84 pg) as the calibration standard. Seagrass leaves were fixed in 4% buffered formaldehyde to mitigate stoichiometric error due to tannins and post-fixed in 3:1 methanol:acetic acid (MAA). DNA was stained with the Feulgen reaction after hydrolysis in 5 M HCl for 90 min at 20 • C. Comparison of genome size of seagrasses with the data for other species of Alismatidae indicated that the ancestral genome of Alismatidae was relatively small.
Molecular Plant-microbe Interactions, 1998
Page 1. 610 / Molecular Plant-Microbe Interactions MPMI Vol. 11, No. 7, 1998, pp. 610617. Public... more Page 1. 610 / Molecular Plant-Microbe Interactions MPMI Vol. 11, No. 7, 1998, pp. 610617. Publication no. M-1998-0413-02R. © 1998 The American Phytopathological Society Membrane Permeabilizing Activity of Pathogenesis-Related Protein Linusitin from Flax Seed ...
American Journal of Botany, 2009
The evolutionary history of maize ( Zea mays subsp. mays ) is of general interest because of its ... more The evolutionary history of maize ( Zea mays subsp. mays ) is of general interest because of its economic and scientifi c importance. Here we show that many cellular traits described previously in developing caryopses of maize are also seen in its wild progenitor teosinte ( Zea mays subsp. parviglumis ). These features, each with a possible role in development, include (1) an early programmed cell death in the maternal placento-chalazal (P-C) layer that may lead to increased hydrolytic conductance to the developing seed; (2) accumulation of phenolics and fl avonoids in the P-C layer that may be related to antimicrobial activity; (3) formation of wall ingrowths in the basal endosperm transfer layer (BETL); (4) localization of cell wall invertase in the BETL, which is attributed to the increased transport capacity of photosynthates to the sink; and (5) endoreduplication in endosperm nuclei suggested to contribute to increased gene expression and greater sink capacity of the developing seed. In maize caryopsis, these cellular traits have been previously attributed to domestication and selection for larger seed size and vigor. Given the conservation of the entire cellular program in developing teosinte caryopses described here, we suggest that these traits evolved independently of domestication and predate human selection pressure.
Physiological and Molecular Plant Pathology, 2000
Stem nodes of the potato virus Y NTN (PVY NTN ) susceptible potato cultivar (Solanum tuberosum cv... more Stem nodes of the potato virus Y NTN (PVY NTN ) susceptible potato cultivar (Solanum tuberosum cv. '' Igor '') were studied to investigate whether alterations in shoot morphology caused by infection with PVY NTN are related to changes in structure and activity of the shoot apical meristem. The PVY NTN causes severe disease symptoms known as the potato tuber necrotic ringspot disease (PTNRD) in susceptible potato plants grown in the field. Although in stem node culture the symptoms are mildly expressed, in systemically PVY NTN -infected plants the shoot height stem diameter, number of leaves and the total leaf area were lower than in the healthy control plants at day 18 and 35 of culture. Histological analysis of the longitudinal sections of the shoot tip revealed that the infected plants had smaller shoot apical meristems due primarily to a lower cell number in different meristem zones. One of the most affected zones of the apical shoot meristem was the peripheral zone, the region in which leaf primordia are induced. The data is consistent in showing that the infection of potato plants with PVY NTN leads to alterations in the shoot apical meristem structure and mitotic activity. These changes are, in turn, reflected in altered overall morphology of the infected plant.
Annals of Botany, 2001
To test the reliability of DNA image cytometry for the measurement of nuclear DNA content in plan... more To test the reliability of DNA image cytometry for the measurement of nuclear DNA content in plant material, we conducted independent experiments in two laboratories using dierent image analysis instruments for densitometric measurement of nuclear DNA amount in Feulgen-stained squash preparations of root tips. The 2C nuclear DNA content of the nine species studied spanned a 100-fold range (approx. 0 . 3±33 pg). The estimates of nuclear DNA content measured with image cytometry methods were comparable to values obtained previously using both photometric cytometry and¯ow cytometry. Image cytometry methods showed little variation among repeated experiments within each laboratory or among dierent operators using the same instrument. Furthermore, the interphase-peak method (measurement of several hundred interphase nuclei per slide) was comparable to the classical prophase/telophase approach (measurement of ten early prophase and ten late telophase nuclei per slide). Hence, DNA image cytometry gives accurate and reproducible results and may be used as an alternative to photometric cytometry in plant nuclear DNA content measurements. In the present study, we propose that two standards for quality control of nuclear DNA content measurement are used in plant DNA image cytometry: (1) the coecient of variation of the peak should be lower than 6 %, and (2) the 4C/2C ratio should be between 1 . 9 and 2 . 1.
Phytochemical Analysis, 2007
Chemical analysis by high-performance liquid chromatography or capillary electrophoresis of plant... more Chemical analysis by high-performance liquid chromatography or capillary electrophoresis of plant pulverized samples, juices or extracts is an excellent method for the authentication of medicinal plant species and their products, particularly when morphological authentication is not possible. In the conventional procedure, chromatograms are integrated and the heights or areas of several peaks are used in a supervised pattern recognition method to confirm the authenticity of the product. We propose a new section approach in analysing chromatograms, where chromatograms are split into sections, which are described by four variables (number of peaks in the section, average retention time of peaks in the section, total area of peaks in the section and average area of peaks in the section), and these variables are then used in statistical analysis. The method is especially useful when the peaks on the chromatogram are not well separated and it is not easy to link individual peaks on one chromatogram with corresponding peaks on other chromatograms. In comparison with the standard procedure, our approach in analyzing chromatographic data of willow-herb (Epilobium and Chamaenerion spp.) extracts was more objective, gave better results and was also easier to perform. Copyright © 2006 John Wiley & Sons, Ltd.
Uploads
Papers by Marina Dermastia