Paula Pongrac - Academia.edu (original) (raw)

Papers by Paula Pongrac

Chemosphere, 2007

Elemental uptake and arbuscular mycorrhizal (AM) colonisation were studied during the life cycle ... more Elemental uptake and arbuscular mycorrhizal (AM) colonisation were studied during the life cycle of field collected Cd/Zn hyperaccumulating Thlaspi praecox (Brassicaceae). Plant biomass and tissue concentrations of Cd, Pb, Zn, Fe and Ni were found to vary during development, while no variation in P, K, Ca, Mn and Cu tissue concentrations were observed. The lowest Cd bioaccumulation in rosette leaves (BAF(RL)) observed during seeding was partially attributed to lower translocation from roots to rosette leaves and partially to high translocation to stalks, indicating a high Cd mobility to reproductive tissues, in line with our previous studies. The highest intensity of AM colonisation (M%) was observed in the flowering phase and was accompanied by increased root Cd, Zn, Pb and Fe contents. In addition, a positive correlation between AM colonisation and Fe contents in rosette leaves was found. The results indicate developmental dependence of AM formation, accompanied by selective changes in nutrient acquisition in T. praecox that are related to increased plant needs, and the protective role of AM colonisation on metal polluted sites during the reproductive period.

Journal of Chemical Ecology, 2008

Thlaspi praecox Wulfen (Brassicaceae) is a perennial Cd/Zn hyperaccumulating plant species that f... more Thlaspi praecox Wulfen (Brassicaceae) is a perennial Cd/Zn hyperaccumulating plant species that forms functional arbuscular mycorrhizal (AM) symbiosis. Glucosinolates (GS) were studied in different organs of field-collected T. praecox at differing plant developmental stages. Additionally, AM colonization was recorded. Total GS concentrations and profiles of nine individual GS varied during the plant life cycle. Novel individual GS that were related to specific developmental phases, mainly to flowering and seed production, were identified. The highest total GS and sinalbin concentrations in rosette leaves were found in the vegetative phase, possibly contributing to protection of young, palatable leaves. The lowest were found in roots during the flowering and the seeding phases. Increased total GS concentrations in roots and enhanced aliphatic GS, especially glucobrassicanapin, in the senescence phase may protect roots from herbivory during winter and early spring. The presence of glucotropaeolin and the absence of glucobrassicanapin in the flowering phase coincided with peak AM colonization. This is the first report on GS profiles in an AM and metal-hyperaccumulating plant.

de Bruijn/Molecular Microbial Ecology of the Rhizosphere, 2013

ABSTRACT There are several metal-hyperaccumulating species within Brassicaceae, which are also ch... more ABSTRACT There are several metal-hyperaccumulating species within Brassicaceae, which are also characterized by high glucosinolates content, which are secondary compounds with pronounced effects in plant – biotic interactions. It is generally believed that glucosinolates prevent the formation of mutualistic symbioses with arbuscular mycorrhizal fungi. Arbuscular mycorrhization is known to develop in the roots of the majority of terrestrial plants, and it is recognized as conferring beneficial effects on plants, primarily by improved nutrient uptake and increased stress resistance. The association of the Cd/Zn-hyperaccumulating Noccaea (Thlaspi) praecox (Brassicaceae) with arbuscular mycorrhizal fungi has been documented under field and laboratory conditions, although the incidence of colonization is low. It was nevertheless demonstrated that this association can lead to improved mineral nutrient uptake, thus confirming the functionality of this symbiosis in N. praecox. This arbuscular mycorrhizal symbiosis is accompanied by changes in glucosinolates patterns, which might be related to the fungal accommodation within the root system, although this relation still needs to be confirmed. Moreover, metal-induced changes in the glucosinolates patterns in N. praecox can indirectly affect the plant defense capabilities, which highlights the complexity of plant responses in metal-hyperaccumulating plants. N. praecox is thus an interesting model species for studies of interactions between accumulated metals, and of the glucosinolates and arbuscular mycorrhizal symbiosis.

International Journal of Phytoremediation, 2009

... a , Katarina Vogel-Mikuš a , Peter Kump b , Marijan Nečemer b & Marjana Regvar a ... Regv... more ... a , Katarina Vogel-Mikuš a , Peter Kump b , Marijan Nečemer b & Marjana Regvar a ... Regvar, M.,Vogel, K., Irgel, N., Wraber, T., Hildebrandt, U., Wilde, P. and Bothe, H. 2003. ... [CrossRef], [PubMed], [Web of Science ®] View all references; Lingfei, Anna, and Zhiwei, 200524. ...

Science of The Total Environment, 2012

A better understanding of the mechanisms that govern copper (Cu) uptake, distribution and toleran... more A better understanding of the mechanisms that govern copper (Cu) uptake, distribution and tolerance in Brassica carinata plants in the presence of chelators is needed before significant progress in chelate-assisted Cu phytoextraction can be made. The aims of this study were therefore to characterise (S,S)-N,N′-ethylenediamine disuccinic acid (EDDS)-assisted Cu uptake, and to compare the spatial distribution patterns of Cu in the roots and leaves of B. carinata plants. The plants were treated with 30 μM or 150 μM CuSO 4 or CuEDDS in hydroponic solution. Quantitative Cu distribution maps and concentration profiles across root and leaf cross-sections of the desorbed plants were obtained by micro-proton induced X-ray emission. In roots, the 30 μM treatments with both CuSO 4 and CuEDDS resulted in higher Cu concentrations in epidermal/cortical regions. At 150 μM CuSO 4 , Cu was mainly accumulated in root vascular bundles, whereas with 150 μM CuEDDS, Cu was detected in endodermis and the adjacent inner cortical cell layer. Under all treatments, except with a H + -ATP-ase inhibitor, the Cu in leaves was localised mainly in vascular tissues. The incubation of plants with 150 μM CuEDDS enhanced metal translocation to shoots, in comparison to the corresponding CuSO 4 treatment. Inhibition of H + -ATPase activity resulted in reduced Cu accumulation in 30 μM CuEDDS-treated roots and 150 μM CuEDDS-treated leaves, and induced changes in Cu distribution in the leaves. This indicates that active mechanisms are involved in retaining Cu in the leaf vascular tissues, which prevent its transport to photosynthetically active tissues. The physiological significance of EDDS-assisted Cu uptake is discussed.

Plant and Soil, 2010

Nuclear ribosomal sequences and Cd, Zn, Pb and Fe accumulation of different populations of the re... more Nuclear ribosomal sequences and Cd, Zn, Pb and Fe accumulation of different populations of the recently discovered Cd/Zn-hyperaccumulating species Thlaspi praecox Wulfen (Noccaea) were studied to reveal their relationships to other representatives of the genus and especially to the well known hyperaccumulator T. caerulescens; comparisons of their accumulating properties were also made. Internal transcribed spacer (ITS) rDNA sequences from eight T. praecox populations from Slovenia showed 99% similarity and formed a sister group to T. caerulescens. Divergence estimates from the ITS rDNA support the origins of T. praecox in the Early Pleistocene, with further fragmentation of T. praecox populations in Slovenia since the Middle Pleistocene. Cd-hyperaccumulating features (>100 mg Cd kg−1 in the above-ground biomass) of T. praecox were seen for two populations collected at polluted sites (Žerjav and Mežica) and one population collected at a non-polluted site (Lokovec). The variability of the Cd concentrations in shoots was almost completely explained by the soil Cd concentrations, and were positively correlated with shoot Zn and Pb concentrations. The results from this molecular and metal accumulation characterisation of T. praecox populations provide new insights into the taxonomic affinities and accumulation potential of this hyperaccumulating species.

Photosynthetica, 2009

The amphibious plant species of intermittent aquatic habitats thrive both submerged and emerged. ... more The amphibious plant species of intermittent aquatic habitats thrive both submerged and emerged. In order to outline the adaptive characters of these two life forms photochemical efficiency of photosystem 2, leaf contents of chlorophyll (Chl) a and b, carotenoids (Car), anthocyanins (Ant), and UV-B absorbing compounds (UV-B abs), and root aerenchyma and arbuscular mycorrhizal (AM) colonisation were studied in Glyceria fluitans, Gratiola officinalis, Ranunculus lingua, Teucrium scordium, Sium latifolium, Sparganium emersum, and Veronica anagallis-aquatica. Water level fluctuations did not exert a severe effect on photon harvesting efficiency. Submerged specimens had higher contents of Car and Ant whereas higher contents of UV-B abs were found in emerged specimens indicating efficient protection against the harmful effects of solar radiation. Roots of all species studied had extensive aerenchyma and were colonised by AM fungi, which were significantly more abundant in emerged specimens. This is the first report on AM symbiosis in S. latifolium and S. emersum.

Environmental and Experimental Botany, 2009

In a model hyperaccumulation study a Cd/Zn hyperaccumulator Thlaspi caerulescens accession Ganges... more In a model hyperaccumulation study a Cd/Zn hyperaccumulator Thlaspi caerulescens accession Ganges and a recently reported Cd/Zn hyperaccumulator Thlaspi praecox grown in increasing Cd and Zn concentrations in the substrate and in field collected polluted soil were compared. Plant biomass, concentrations of Cd and Zn, total chlorophylls and anthocyanins, antioxidative stress parameters and activities of selected antioxidative enzymes were compared. Increasing Cd, but not Zn in the substrate resulted in the increase of biomass of roots and shoots of T. praecox and T. caerulescens. The two species hyperaccumulated Cd in the shoots to a similar extent, whereas T. caerulescens accumulated more Zn in the shoots than T. praecox. Cadmium amendment decreased total chlorophyll concentration and glutathione reductase activity, and increased non-protein thiols concentration only in T. praecox, suggesting that it is less tolerant to Cd than T. caerulescens. In the field-contaminated soil, T. caerulescens accumulated higher Cd concentrations; but as T. praecox produced higher biomass, both species have similar ability to extract Cd.

Chemosphere, 2007

Elemental uptake and arbuscular mycorrhizal (AM) colonisation were studied during the life cycle ... more Elemental uptake and arbuscular mycorrhizal (AM) colonisation were studied during the life cycle of field collected Cd/Zn hyperaccumulating Thlaspi praecox (Brassicaceae). Plant biomass and tissue concentrations of Cd, Pb, Zn, Fe and Ni were found to vary during development, while no variation in P, K, Ca, Mn and Cu tissue concentrations were observed. The lowest Cd bioaccumulation in rosette leaves (BAFRL) observed during seeding was partially attributed to lower translocation from roots to rosette leaves and partially to high translocation to stalks, indicating a high Cd mobility to reproductive tissues, in line with our previous studies. The highest intensity of AM colonisation (M%) was observed in the flowering phase and was accompanied by increased root Cd, Zn, Pb and Fe contents. In addition, a positive correlation between AM colonisation and Fe contents in rosette leaves was found. The results indicate developmental dependence of AM formation, accompanied by selective changes in nutrient acquisition in T. praecox that are related to increased plant needs, and the protective role of AM colonisation on metal polluted sites during the reproductive period.

Environmental Pollution, 2007

Cd, Zn and Pb accumulation, spatial distribution within seeds and germinating seedlings, and seed... more Cd, Zn and Pb accumulation, spatial distribution within seeds and germinating seedlings, and seeds fitness of metal hyperaccumulating Thlaspi praecox were investigated in order to gain more knowledge on plant reproductive success at metal polluted sites. The seeds contained up to 1351 μg g−1 (dry weight) of Cd, 121 μg g−1 of Zn and 17 μg g−1 of Pb. Seed fitness was negatively influenced by seed Cd hyperaccumulation. Nevertheless, the viability of seeds was decreased by maximally 20%, indicating very efficient tolerance of the plant embryos to Cd. Localisation by micro-PIXE revealed preferential storage of most elements in the embryonic axis. Cd and Zn were preferentially localised in the epidermis of cotyledons. The restriction of seed Pb and Zn uptake and hyperaccumulation of Cd, accompanied by partitioning of Cd in the epidermal tissues of cotyledons, may enable the survival of T. praecox embryos and seedlings in Cd polluted environments.

Water and Nutrient Management in Natural and Constructed Wetlands, 2010

Environmental conditions in wetlands were long thought to suppress mycorrhizal fungi and it has b... more Environmental conditions in wetlands were long thought to suppress mycorrhizal fungi and it has been assumed that mycorrhiza in wetlands is limited and is of little significance. This contribution summarises the presence of arbuscular mycorrhizal (AM) fungi and dark-septate endophytes (DSE) in different habitats of the intermittent Lake Cerknica. Mycorrhizal colonisation of wetland plants from the following wetland habitats was

International Journal of Phytoremediation, 2009

Thlaspi praecox (Brassicaceae) is a recently discovered metal hyperaccumulating plant species col... more Thlaspi praecox (Brassicaceae) is a recently discovered metal hyperaccumulating plant species colonized by arbuscular mycorrhizal fungi (AMF). The identity and diversity of the AMF colonizing its roots have not been determined so far. Therefore, T. praecox was inoculated with an indigenous fungal mixture from a metal polluted site and grown in original polluted soil/ commercial substrate mixtures (i.e., 100%, 50%, and 25%). Low to moderate mycorrhizal frequencies (F = 33–68%) and only rare arbuscules were observed. Densities of vesicles and microsclerotia, typical structures of dark septate endophytes (DSE), were greater in pots with 100% original polluted soil. In contrast, the highest diversity of fungal genotypes was observed in the roots from 25% polluted soil/ commercial substrate mixture, with the lowest soil concentrations of Cd, Zn, and Pb. The sequences obtained corresponded to Glomus species (Glomeromycota), to putative DSE Phialophora verrucosa and Rhizoctonia sp. and to some other fungi from Asco- and Basidiomycota, that are known to associate with plants, namely Capnobotryella sp., Penicillium brevicompactum, Rodotorula aurantiaca and Rodotorula slooffiae. This is the first report of DSE occurrence in roots of hyperaccumulating T. praecox, a promising candidate for phytoextraction.

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2011

Micro-proton induced X-ray emission (micro-PIXE) method was applied to study the micro-localizati... more Micro-proton induced X-ray emission (micro-PIXE) method was applied to study the micro-localization of silver (Ag) in digestive glands of a terrestrial arthropod (Porcellio scaber) after feeding on silver nanoparticles (nano-Ag) dosed food. The aim of our work was to assess whether feeding on nano-Ag results in the assimilation of silver (Ag) in digestive gland cells. To study micro-localization and elemental distribution of Ag, the animals were fed on food dosed with nanoparticles for 14 days under controlled laboratory conditions. At the end of the feeding exposure, the animals were dissected and digestive glands prepared for micro-PIXE analyses and TEM investigation. The results obtained by micro-PIXE documented high amounts of Ag inside S-cells of the digestive gland epithelium; however, TEM investigation did not show particle aggregates inside digestive gland cells. Also no adverse effect on feeding behavior was recorded what is a measure of toxic effects. We explain the presence of Ag inside the cells as a result of the assimilation of dissoluted Ag ions from ingested nano-Ag particles. Assimilation of excessive amounts of ingested metal ions in S-cells is a well known metal detoxification mechanism in isopods. We discuss the advantages of using micro-PIXE for the micro-localization of elements in biological tissue in studies of interactions between nanoparticles and biological systems.

The main aim of contemporary ecotoxicological studies is to determine the bioavailability, toxici... more The main aim of contemporary ecotoxicological studies is to determine the bioavailability, toxicity and risk relationships of trace-element contaminants in ecosystems. Discussions thus focus primarily on the concentrations of elements in soils, their dynamics, and the impact they have on microorganisms, plants, animals and the ecosystem as a whole. However, before the basic ecotoxicological principles can be discussed, the appropriate analytical methods for addressing particular question(s) need to be chosen from among the broad array of physicochemical analytical methods that are available. Together with the sampling strategy and preparation, these are key issues that affect the final outcome. In this chapter, we mainly focus on the presentation and use of X-ray fluorescence/absorption-based techniques. These include standard and total reflection X-ray fluorescence, micro-proton-induced X-ray emission, and X-ray absorption spectroscopy (such as extended X-ray absorption fine structure and X-ray absorption near-edge structure) for the analysis of trace-element concentrations and their coordination in biological samples.

Plant and Soil, 2010

Nuclear ribosomal sequences and Cd, Zn, Pb and Fe accumulation of different populations of the re... more Nuclear ribosomal sequences and Cd, Zn, Pb and Fe accumulation of different populations of the recently discovered Cd/Zn-hyperaccumulating species Thlaspi praecox Wulfen (Noccaea) were studied to reveal their relationships to other representatives of the genus and especially to the well known hyperaccumulator T. caerulescens; comparisons of their accumulating properties were also made. Internal transcribed spacer (ITS) rDNA sequences from eight T. praecox populations from Slovenia showed 99% similarity and formed a sister group to T. caerulescens. Divergence estimates from the ITS rDNA support the origins of T. praecox in the Early Pleistocene, with further fragmentation of T. praecox populations in Slovenia since the Middle Pleistocene. Cdhyperaccumulating features (>100 mg Cd kg −1 in the above-ground biomass) of T. praecox were seen for two populations collected at polluted sites (Žerjav and Mežica) and one population collected at a non-polluted site (Lokovec). The variability of the Cd concentrations in shoots was almost completely explained by the soil Cd concentrations, and were positively correlated with shoot Zn and Pb concentrations. The results from this molecular and metal accumulation characterisation of T. praecox populations provide new insights into the taxonomic affinities and accumulation potential of this hyperaccumulating species.

Plant and Soil, 2006

The influence of Cd on growth, Cd accumulation and glucosinolate (GS) contents was investigated i... more The influence of Cd on growth, Cd accumulation and glucosinolate (GS) contents was investigated in Thlaspi praecox in comparison to Thlaspi arvense. Accumulation of up to 2,700 lg Cd g -1 dry weight in shoots of T. praecox, growing in nutrient solution with 50 lM Cd without growth inhibition, confirmed this species as a Cd-hyperaccumulator. Cadmium increased the level of total GS in T. praecox without a statistically significant influence on total sulphur. This increase in GS was due to the enhancement of benzyl-GS, mainly sinalbin. In the Cd sensitive T. arvense Cd caused a shift from alkenyl-GS, mainly sinigrin, to indolyl-GS. The Cd-induced increase of total GS in T. praecox indicates that in this species Cd hyperaccumulation is not linked to trade-off of organic defences. The distinctive influence of Cd on GS profiles in Cd-sensitive T. arvense and Cd-tolerant T. praecox favouring indolyl-GS and benzyl-GS, respectively, is discussed in relation to jasmonate and salicylate as possible key molecules in Cd-stress transduction in these contrasting Thlaspi species.

Photosynthetica, 2009

The amphibious plant species of intermittent aquatic habitats thrive both submerged and emerged. ... more The amphibious plant species of intermittent aquatic habitats thrive both submerged and emerged. In order to outline the adaptive characters of these two life forms photochemical efficiency of photosystem 2, leaf contents of chlorophyll (Chl) a and b, carotenoids (Car), anthocyanins (Ant), and UV-B absorbing compounds (UV-B abs), and root aerenchyma and arbuscular mycorrhizal (AM) colonisation were studied in Glyceria fluitans, Gratiola officinalis, Ranunculus lingua, Teucrium scordium, Sium latifolium, Sparganium emersum, and Veronica anagallis-aquatica. Water level fluctuations did not exert a severe effect on photon harvesting efficiency. Submerged specimens had higher contents of Car and Ant whereas higher contents of UV-B abs were found in emerged specimens indicating efficient protection against the harmful effects of solar radiation. Roots of all species studied had extensive aerenchyma and were colonised by AM fungi, which were significantly more abundant in emerged specimens. This is the first report on AM symbiosis in S. latifolium and S. emersum. /F m of PS2 -potential photochemical efficiency; M% -mycorrhizal intensity; PS -photosystem; SLA -specific leaf area; Y -actual photochemical efficiency of PS2. Acknowledgements: This research was financed by the Ministry of Education, Science and Sport, Republic of Slovenia, through the programmes "Biology of plants" (P1-0212) and "Young researchers" (3311-03-831202 and 3311-04-831248). The authors thank undergraduate students U. Godec, U. Kačar, M. Klemenc, P. Maurič, and M. Pociecha for help with analyses, and to Dr Roger Pain for revising the English writing.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2011

Micro-proton induced X-ray emission (micro-PIXE) method was applied to study the micro-localizati... more Micro-proton induced X-ray emission (micro-PIXE) method was applied to study the micro-localization of silver (Ag) in digestive glands of a terrestrial arthropod (Porcellio scaber) after feeding on silver nanoparticles (nano-Ag) dosed food. The aim of our work was to assess whether feeding on nano-Ag results in the assimilation of silver (Ag) in digestive gland cells. To study micro-localization and elemental distribution of Ag, the animals were fed on food dosed with nanoparticles for 14 days under controlled laboratory conditions. At the end of the feeding exposure, the animals were dissected and digestive glands prepared for micro-PIXE analyses and TEM investigation. The results obtained by micro-PIXE documented high amounts of Ag inside S-cells of the digestive gland epithelium; however, TEM investigation did not show particle aggregates inside digestive gland cells. Also no adverse effect on feeding behavior was recorded what is a measure of toxic effects. We explain the presence of Ag inside the cells as a result of the assimilation of dissoluted Ag ions from ingested nano-Ag particles. Assimilation of excessive amounts of ingested metal ions in S-cells is a well known metal detoxification mechanism in isopods. We discuss the advantages of using micro-PIXE for the micro-localization of elements in biological tissue in studies of interactions between nanoparticles and biological systems.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2010

Please cite this article in press as: P. Pongrac et al., Cd induced redistribution of elements wi... more Please cite this article in press as: P. Pongrac et al., Cd induced redistribution of elements within leaves of the Cd/Zn hyperaccumulator Thlaspi praecox as revealed by micro-PIXE, Nucl.

Chemosphere, 2007

Elemental uptake and arbuscular mycorrhizal (AM) colonisation were studied during the life cycle ... more Elemental uptake and arbuscular mycorrhizal (AM) colonisation were studied during the life cycle of field collected Cd/Zn hyperaccumulating Thlaspi praecox (Brassicaceae). Plant biomass and tissue concentrations of Cd, Pb, Zn, Fe and Ni were found to vary during development, while no variation in P, K, Ca, Mn and Cu tissue concentrations were observed. The lowest Cd bioaccumulation in rosette leaves (BAF(RL)) observed during seeding was partially attributed to lower translocation from roots to rosette leaves and partially to high translocation to stalks, indicating a high Cd mobility to reproductive tissues, in line with our previous studies. The highest intensity of AM colonisation (M%) was observed in the flowering phase and was accompanied by increased root Cd, Zn, Pb and Fe contents. In addition, a positive correlation between AM colonisation and Fe contents in rosette leaves was found. The results indicate developmental dependence of AM formation, accompanied by selective changes in nutrient acquisition in T. praecox that are related to increased plant needs, and the protective role of AM colonisation on metal polluted sites during the reproductive period.

Journal of Chemical Ecology, 2008

Thlaspi praecox Wulfen (Brassicaceae) is a perennial Cd/Zn hyperaccumulating plant species that f... more Thlaspi praecox Wulfen (Brassicaceae) is a perennial Cd/Zn hyperaccumulating plant species that forms functional arbuscular mycorrhizal (AM) symbiosis. Glucosinolates (GS) were studied in different organs of field-collected T. praecox at differing plant developmental stages. Additionally, AM colonization was recorded. Total GS concentrations and profiles of nine individual GS varied during the plant life cycle. Novel individual GS that were related to specific developmental phases, mainly to flowering and seed production, were identified. The highest total GS and sinalbin concentrations in rosette leaves were found in the vegetative phase, possibly contributing to protection of young, palatable leaves. The lowest were found in roots during the flowering and the seeding phases. Increased total GS concentrations in roots and enhanced aliphatic GS, especially glucobrassicanapin, in the senescence phase may protect roots from herbivory during winter and early spring. The presence of glucotropaeolin and the absence of glucobrassicanapin in the flowering phase coincided with peak AM colonization. This is the first report on GS profiles in an AM and metal-hyperaccumulating plant.

de Bruijn/Molecular Microbial Ecology of the Rhizosphere, 2013

ABSTRACT There are several metal-hyperaccumulating species within Brassicaceae, which are also ch... more ABSTRACT There are several metal-hyperaccumulating species within Brassicaceae, which are also characterized by high glucosinolates content, which are secondary compounds with pronounced effects in plant – biotic interactions. It is generally believed that glucosinolates prevent the formation of mutualistic symbioses with arbuscular mycorrhizal fungi. Arbuscular mycorrhization is known to develop in the roots of the majority of terrestrial plants, and it is recognized as conferring beneficial effects on plants, primarily by improved nutrient uptake and increased stress resistance. The association of the Cd/Zn-hyperaccumulating Noccaea (Thlaspi) praecox (Brassicaceae) with arbuscular mycorrhizal fungi has been documented under field and laboratory conditions, although the incidence of colonization is low. It was nevertheless demonstrated that this association can lead to improved mineral nutrient uptake, thus confirming the functionality of this symbiosis in N. praecox. This arbuscular mycorrhizal symbiosis is accompanied by changes in glucosinolates patterns, which might be related to the fungal accommodation within the root system, although this relation still needs to be confirmed. Moreover, metal-induced changes in the glucosinolates patterns in N. praecox can indirectly affect the plant defense capabilities, which highlights the complexity of plant responses in metal-hyperaccumulating plants. N. praecox is thus an interesting model species for studies of interactions between accumulated metals, and of the glucosinolates and arbuscular mycorrhizal symbiosis.

International Journal of Phytoremediation, 2009

... a , Katarina Vogel-Mikuš a , Peter Kump b , Marijan Nečemer b & Marjana Regvar a ... Regv... more ... a , Katarina Vogel-Mikuš a , Peter Kump b , Marijan Nečemer b & Marjana Regvar a ... Regvar, M.,Vogel, K., Irgel, N., Wraber, T., Hildebrandt, U., Wilde, P. and Bothe, H. 2003. ... [CrossRef], [PubMed], [Web of Science ®] View all references; Lingfei, Anna, and Zhiwei, 200524. ...

Science of The Total Environment, 2012

A better understanding of the mechanisms that govern copper (Cu) uptake, distribution and toleran... more A better understanding of the mechanisms that govern copper (Cu) uptake, distribution and tolerance in Brassica carinata plants in the presence of chelators is needed before significant progress in chelate-assisted Cu phytoextraction can be made. The aims of this study were therefore to characterise (S,S)-N,N′-ethylenediamine disuccinic acid (EDDS)-assisted Cu uptake, and to compare the spatial distribution patterns of Cu in the roots and leaves of B. carinata plants. The plants were treated with 30 μM or 150 μM CuSO 4 or CuEDDS in hydroponic solution. Quantitative Cu distribution maps and concentration profiles across root and leaf cross-sections of the desorbed plants were obtained by micro-proton induced X-ray emission. In roots, the 30 μM treatments with both CuSO 4 and CuEDDS resulted in higher Cu concentrations in epidermal/cortical regions. At 150 μM CuSO 4 , Cu was mainly accumulated in root vascular bundles, whereas with 150 μM CuEDDS, Cu was detected in endodermis and the adjacent inner cortical cell layer. Under all treatments, except with a H + -ATP-ase inhibitor, the Cu in leaves was localised mainly in vascular tissues. The incubation of plants with 150 μM CuEDDS enhanced metal translocation to shoots, in comparison to the corresponding CuSO 4 treatment. Inhibition of H + -ATPase activity resulted in reduced Cu accumulation in 30 μM CuEDDS-treated roots and 150 μM CuEDDS-treated leaves, and induced changes in Cu distribution in the leaves. This indicates that active mechanisms are involved in retaining Cu in the leaf vascular tissues, which prevent its transport to photosynthetically active tissues. The physiological significance of EDDS-assisted Cu uptake is discussed.

Plant and Soil, 2010

Nuclear ribosomal sequences and Cd, Zn, Pb and Fe accumulation of different populations of the re... more Nuclear ribosomal sequences and Cd, Zn, Pb and Fe accumulation of different populations of the recently discovered Cd/Zn-hyperaccumulating species Thlaspi praecox Wulfen (Noccaea) were studied to reveal their relationships to other representatives of the genus and especially to the well known hyperaccumulator T. caerulescens; comparisons of their accumulating properties were also made. Internal transcribed spacer (ITS) rDNA sequences from eight T. praecox populations from Slovenia showed 99% similarity and formed a sister group to T. caerulescens. Divergence estimates from the ITS rDNA support the origins of T. praecox in the Early Pleistocene, with further fragmentation of T. praecox populations in Slovenia since the Middle Pleistocene. Cd-hyperaccumulating features (>100 mg Cd kg−1 in the above-ground biomass) of T. praecox were seen for two populations collected at polluted sites (Žerjav and Mežica) and one population collected at a non-polluted site (Lokovec). The variability of the Cd concentrations in shoots was almost completely explained by the soil Cd concentrations, and were positively correlated with shoot Zn and Pb concentrations. The results from this molecular and metal accumulation characterisation of T. praecox populations provide new insights into the taxonomic affinities and accumulation potential of this hyperaccumulating species.

Photosynthetica, 2009

The amphibious plant species of intermittent aquatic habitats thrive both submerged and emerged. ... more The amphibious plant species of intermittent aquatic habitats thrive both submerged and emerged. In order to outline the adaptive characters of these two life forms photochemical efficiency of photosystem 2, leaf contents of chlorophyll (Chl) a and b, carotenoids (Car), anthocyanins (Ant), and UV-B absorbing compounds (UV-B abs), and root aerenchyma and arbuscular mycorrhizal (AM) colonisation were studied in Glyceria fluitans, Gratiola officinalis, Ranunculus lingua, Teucrium scordium, Sium latifolium, Sparganium emersum, and Veronica anagallis-aquatica. Water level fluctuations did not exert a severe effect on photon harvesting efficiency. Submerged specimens had higher contents of Car and Ant whereas higher contents of UV-B abs were found in emerged specimens indicating efficient protection against the harmful effects of solar radiation. Roots of all species studied had extensive aerenchyma and were colonised by AM fungi, which were significantly more abundant in emerged specimens. This is the first report on AM symbiosis in S. latifolium and S. emersum.

Environmental and Experimental Botany, 2009

In a model hyperaccumulation study a Cd/Zn hyperaccumulator Thlaspi caerulescens accession Ganges... more In a model hyperaccumulation study a Cd/Zn hyperaccumulator Thlaspi caerulescens accession Ganges and a recently reported Cd/Zn hyperaccumulator Thlaspi praecox grown in increasing Cd and Zn concentrations in the substrate and in field collected polluted soil were compared. Plant biomass, concentrations of Cd and Zn, total chlorophylls and anthocyanins, antioxidative stress parameters and activities of selected antioxidative enzymes were compared. Increasing Cd, but not Zn in the substrate resulted in the increase of biomass of roots and shoots of T. praecox and T. caerulescens. The two species hyperaccumulated Cd in the shoots to a similar extent, whereas T. caerulescens accumulated more Zn in the shoots than T. praecox. Cadmium amendment decreased total chlorophyll concentration and glutathione reductase activity, and increased non-protein thiols concentration only in T. praecox, suggesting that it is less tolerant to Cd than T. caerulescens. In the field-contaminated soil, T. caerulescens accumulated higher Cd concentrations; but as T. praecox produced higher biomass, both species have similar ability to extract Cd.

Chemosphere, 2007

Elemental uptake and arbuscular mycorrhizal (AM) colonisation were studied during the life cycle ... more Elemental uptake and arbuscular mycorrhizal (AM) colonisation were studied during the life cycle of field collected Cd/Zn hyperaccumulating Thlaspi praecox (Brassicaceae). Plant biomass and tissue concentrations of Cd, Pb, Zn, Fe and Ni were found to vary during development, while no variation in P, K, Ca, Mn and Cu tissue concentrations were observed. The lowest Cd bioaccumulation in rosette leaves (BAFRL) observed during seeding was partially attributed to lower translocation from roots to rosette leaves and partially to high translocation to stalks, indicating a high Cd mobility to reproductive tissues, in line with our previous studies. The highest intensity of AM colonisation (M%) was observed in the flowering phase and was accompanied by increased root Cd, Zn, Pb and Fe contents. In addition, a positive correlation between AM colonisation and Fe contents in rosette leaves was found. The results indicate developmental dependence of AM formation, accompanied by selective changes in nutrient acquisition in T. praecox that are related to increased plant needs, and the protective role of AM colonisation on metal polluted sites during the reproductive period.

Environmental Pollution, 2007

Cd, Zn and Pb accumulation, spatial distribution within seeds and germinating seedlings, and seed... more Cd, Zn and Pb accumulation, spatial distribution within seeds and germinating seedlings, and seeds fitness of metal hyperaccumulating Thlaspi praecox were investigated in order to gain more knowledge on plant reproductive success at metal polluted sites. The seeds contained up to 1351 μg g−1 (dry weight) of Cd, 121 μg g−1 of Zn and 17 μg g−1 of Pb. Seed fitness was negatively influenced by seed Cd hyperaccumulation. Nevertheless, the viability of seeds was decreased by maximally 20%, indicating very efficient tolerance of the plant embryos to Cd. Localisation by micro-PIXE revealed preferential storage of most elements in the embryonic axis. Cd and Zn were preferentially localised in the epidermis of cotyledons. The restriction of seed Pb and Zn uptake and hyperaccumulation of Cd, accompanied by partitioning of Cd in the epidermal tissues of cotyledons, may enable the survival of T. praecox embryos and seedlings in Cd polluted environments.

Water and Nutrient Management in Natural and Constructed Wetlands, 2010

Environmental conditions in wetlands were long thought to suppress mycorrhizal fungi and it has b... more Environmental conditions in wetlands were long thought to suppress mycorrhizal fungi and it has been assumed that mycorrhiza in wetlands is limited and is of little significance. This contribution summarises the presence of arbuscular mycorrhizal (AM) fungi and dark-septate endophytes (DSE) in different habitats of the intermittent Lake Cerknica. Mycorrhizal colonisation of wetland plants from the following wetland habitats was

International Journal of Phytoremediation, 2009

Thlaspi praecox (Brassicaceae) is a recently discovered metal hyperaccumulating plant species col... more Thlaspi praecox (Brassicaceae) is a recently discovered metal hyperaccumulating plant species colonized by arbuscular mycorrhizal fungi (AMF). The identity and diversity of the AMF colonizing its roots have not been determined so far. Therefore, T. praecox was inoculated with an indigenous fungal mixture from a metal polluted site and grown in original polluted soil/ commercial substrate mixtures (i.e., 100%, 50%, and 25%). Low to moderate mycorrhizal frequencies (F = 33–68%) and only rare arbuscules were observed. Densities of vesicles and microsclerotia, typical structures of dark septate endophytes (DSE), were greater in pots with 100% original polluted soil. In contrast, the highest diversity of fungal genotypes was observed in the roots from 25% polluted soil/ commercial substrate mixture, with the lowest soil concentrations of Cd, Zn, and Pb. The sequences obtained corresponded to Glomus species (Glomeromycota), to putative DSE Phialophora verrucosa and Rhizoctonia sp. and to some other fungi from Asco- and Basidiomycota, that are known to associate with plants, namely Capnobotryella sp., Penicillium brevicompactum, Rodotorula aurantiaca and Rodotorula slooffiae. This is the first report of DSE occurrence in roots of hyperaccumulating T. praecox, a promising candidate for phytoextraction.

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2011

Micro-proton induced X-ray emission (micro-PIXE) method was applied to study the micro-localizati... more Micro-proton induced X-ray emission (micro-PIXE) method was applied to study the micro-localization of silver (Ag) in digestive glands of a terrestrial arthropod (Porcellio scaber) after feeding on silver nanoparticles (nano-Ag) dosed food. The aim of our work was to assess whether feeding on nano-Ag results in the assimilation of silver (Ag) in digestive gland cells. To study micro-localization and elemental distribution of Ag, the animals were fed on food dosed with nanoparticles for 14 days under controlled laboratory conditions. At the end of the feeding exposure, the animals were dissected and digestive glands prepared for micro-PIXE analyses and TEM investigation. The results obtained by micro-PIXE documented high amounts of Ag inside S-cells of the digestive gland epithelium; however, TEM investigation did not show particle aggregates inside digestive gland cells. Also no adverse effect on feeding behavior was recorded what is a measure of toxic effects. We explain the presence of Ag inside the cells as a result of the assimilation of dissoluted Ag ions from ingested nano-Ag particles. Assimilation of excessive amounts of ingested metal ions in S-cells is a well known metal detoxification mechanism in isopods. We discuss the advantages of using micro-PIXE for the micro-localization of elements in biological tissue in studies of interactions between nanoparticles and biological systems.

The main aim of contemporary ecotoxicological studies is to determine the bioavailability, toxici... more The main aim of contemporary ecotoxicological studies is to determine the bioavailability, toxicity and risk relationships of trace-element contaminants in ecosystems. Discussions thus focus primarily on the concentrations of elements in soils, their dynamics, and the impact they have on microorganisms, plants, animals and the ecosystem as a whole. However, before the basic ecotoxicological principles can be discussed, the appropriate analytical methods for addressing particular question(s) need to be chosen from among the broad array of physicochemical analytical methods that are available. Together with the sampling strategy and preparation, these are key issues that affect the final outcome. In this chapter, we mainly focus on the presentation and use of X-ray fluorescence/absorption-based techniques. These include standard and total reflection X-ray fluorescence, micro-proton-induced X-ray emission, and X-ray absorption spectroscopy (such as extended X-ray absorption fine structure and X-ray absorption near-edge structure) for the analysis of trace-element concentrations and their coordination in biological samples.

Plant and Soil, 2010

Nuclear ribosomal sequences and Cd, Zn, Pb and Fe accumulation of different populations of the re... more Nuclear ribosomal sequences and Cd, Zn, Pb and Fe accumulation of different populations of the recently discovered Cd/Zn-hyperaccumulating species Thlaspi praecox Wulfen (Noccaea) were studied to reveal their relationships to other representatives of the genus and especially to the well known hyperaccumulator T. caerulescens; comparisons of their accumulating properties were also made. Internal transcribed spacer (ITS) rDNA sequences from eight T. praecox populations from Slovenia showed 99% similarity and formed a sister group to T. caerulescens. Divergence estimates from the ITS rDNA support the origins of T. praecox in the Early Pleistocene, with further fragmentation of T. praecox populations in Slovenia since the Middle Pleistocene. Cdhyperaccumulating features (>100 mg Cd kg −1 in the above-ground biomass) of T. praecox were seen for two populations collected at polluted sites (Žerjav and Mežica) and one population collected at a non-polluted site (Lokovec). The variability of the Cd concentrations in shoots was almost completely explained by the soil Cd concentrations, and were positively correlated with shoot Zn and Pb concentrations. The results from this molecular and metal accumulation characterisation of T. praecox populations provide new insights into the taxonomic affinities and accumulation potential of this hyperaccumulating species.

Plant and Soil, 2006

The influence of Cd on growth, Cd accumulation and glucosinolate (GS) contents was investigated i... more The influence of Cd on growth, Cd accumulation and glucosinolate (GS) contents was investigated in Thlaspi praecox in comparison to Thlaspi arvense. Accumulation of up to 2,700 lg Cd g -1 dry weight in shoots of T. praecox, growing in nutrient solution with 50 lM Cd without growth inhibition, confirmed this species as a Cd-hyperaccumulator. Cadmium increased the level of total GS in T. praecox without a statistically significant influence on total sulphur. This increase in GS was due to the enhancement of benzyl-GS, mainly sinalbin. In the Cd sensitive T. arvense Cd caused a shift from alkenyl-GS, mainly sinigrin, to indolyl-GS. The Cd-induced increase of total GS in T. praecox indicates that in this species Cd hyperaccumulation is not linked to trade-off of organic defences. The distinctive influence of Cd on GS profiles in Cd-sensitive T. arvense and Cd-tolerant T. praecox favouring indolyl-GS and benzyl-GS, respectively, is discussed in relation to jasmonate and salicylate as possible key molecules in Cd-stress transduction in these contrasting Thlaspi species.

Photosynthetica, 2009

The amphibious plant species of intermittent aquatic habitats thrive both submerged and emerged. ... more The amphibious plant species of intermittent aquatic habitats thrive both submerged and emerged. In order to outline the adaptive characters of these two life forms photochemical efficiency of photosystem 2, leaf contents of chlorophyll (Chl) a and b, carotenoids (Car), anthocyanins (Ant), and UV-B absorbing compounds (UV-B abs), and root aerenchyma and arbuscular mycorrhizal (AM) colonisation were studied in Glyceria fluitans, Gratiola officinalis, Ranunculus lingua, Teucrium scordium, Sium latifolium, Sparganium emersum, and Veronica anagallis-aquatica. Water level fluctuations did not exert a severe effect on photon harvesting efficiency. Submerged specimens had higher contents of Car and Ant whereas higher contents of UV-B abs were found in emerged specimens indicating efficient protection against the harmful effects of solar radiation. Roots of all species studied had extensive aerenchyma and were colonised by AM fungi, which were significantly more abundant in emerged specimens. This is the first report on AM symbiosis in S. latifolium and S. emersum. /F m of PS2 -potential photochemical efficiency; M% -mycorrhizal intensity; PS -photosystem; SLA -specific leaf area; Y -actual photochemical efficiency of PS2. Acknowledgements: This research was financed by the Ministry of Education, Science and Sport, Republic of Slovenia, through the programmes "Biology of plants" (P1-0212) and "Young researchers" (3311-03-831202 and 3311-04-831248). The authors thank undergraduate students U. Godec, U. Kačar, M. Klemenc, P. Maurič, and M. Pociecha for help with analyses, and to Dr Roger Pain for revising the English writing.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2011

Micro-proton induced X-ray emission (micro-PIXE) method was applied to study the micro-localizati... more Micro-proton induced X-ray emission (micro-PIXE) method was applied to study the micro-localization of silver (Ag) in digestive glands of a terrestrial arthropod (Porcellio scaber) after feeding on silver nanoparticles (nano-Ag) dosed food. The aim of our work was to assess whether feeding on nano-Ag results in the assimilation of silver (Ag) in digestive gland cells. To study micro-localization and elemental distribution of Ag, the animals were fed on food dosed with nanoparticles for 14 days under controlled laboratory conditions. At the end of the feeding exposure, the animals were dissected and digestive glands prepared for micro-PIXE analyses and TEM investigation. The results obtained by micro-PIXE documented high amounts of Ag inside S-cells of the digestive gland epithelium; however, TEM investigation did not show particle aggregates inside digestive gland cells. Also no adverse effect on feeding behavior was recorded what is a measure of toxic effects. We explain the presence of Ag inside the cells as a result of the assimilation of dissoluted Ag ions from ingested nano-Ag particles. Assimilation of excessive amounts of ingested metal ions in S-cells is a well known metal detoxification mechanism in isopods. We discuss the advantages of using micro-PIXE for the micro-localization of elements in biological tissue in studies of interactions between nanoparticles and biological systems.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2010

Please cite this article in press as: P. Pongrac et al., Cd induced redistribution of elements wi... more Please cite this article in press as: P. Pongrac et al., Cd induced redistribution of elements within leaves of the Cd/Zn hyperaccumulator Thlaspi praecox as revealed by micro-PIXE, Nucl.