Modyfikacja procesu transpiracji a efektywność indukowanej fitoekstrakcji ołowiu i kadmu w wybranych gatunkach roślin

The aim of this paper was to determine the relationship between transpiration and the effectiveness of induced phytoextraction of Pb and Cd in Indian mustard (Brassica juncea) and sunflower (Helianthus annuus) plants. Fusicoccin (FC) at the concentration of 10–6 M and KCl (25—100 mM), which were sprayed on the shoots of Indian mustard, increased considerably transpiration in plants grown in hydroponic culture, both in basal medium and basal medium supplemented with EDTA, Pb and Cd. Although the total amount of transpired water was significantly greater in the treated plants when compared with control, the dynamics of transpiration varied during the experiment and depended on the composition of hydroponic solution. In Indian mustard plants grown in the basal medium supplemented with EDTA, Pb and Cd and sprayed with FC and KCl on the above ground parts of plants a positive correlation between transpiration and the content of lead and cadmium in the shoots was observed. A significant positive relationship between the translocation of Pb and Cd and their accumulation in shoots was found 20—35 hours after spraying. In the processes of translocation and accumulation the synergistic effect of FC and KCl was observed. The investigation also showed a high positive correlation between the concentration of the KCl sprayed on the above ground parts and the content of Pb and Cd in the shoots of Indian mustard, which does not depend on transpiration. In Indian mustard and sunflower plants grown in metal contaminated soil supplemented with EDTA no correlation between transpiration and the content of Pb and Cd in the shoots was found. The synergistic effect of FC and KCl on accumulation of Pb and Cd in the above ground parts was also not observed. Pot experiments showed that in induced phytoextraction the content of Pb and Cd is regulated by the level of induction of hyperaccumulation in plants and not by transpiration. Investigations on induced phytoextraction of Pb and Cd showed that when the transpiration is modified discrepancies between the results obtained in experiments in hy-droponic cultures and pot experiments can be found. For this reason pot experiments should be the main point of reference in planning field experiments. The spraying of Indian mustard and sunflower plants with glyphopsate and the application of EDTA to the Pb, Cd and Zn contaminated soil resulted in a marked increase in the Pb and Cd content in the shoots and the level of metal accumulation was similar in both investigated plant species. Moreover, it was found that glyphosate significantly increased the membrane permeability and the inductive effect of EDTA. Simultaneous application of EDTA and glyphosate resulted in apoplastic and symplastic transport of PbEDTA and CdEDTA through the endodermis. Transpiration plays a negligible role in this transport. The low membrane permeability caused by the low level of induction of metal hyperaccumulation is mainly connected with apoplastic transport of PbEDTA and CdEDTA. This transport depends on transpiration and can be modified by factors that have an effect on transpiration rate

Arbuscular mycorrhiza of Deschampsia cespitosa (Poaceae) at different soil depths in highly metal-contaminated site in southern Poland

This study presents root colonization of Deschampsia cespitosa growing in the immediate vicinity of a former Pb/Zn smelter by arbuscular mycorhizal fungi (AMF) and dark septated endophytes (DSE) at different soil depths. AMF spores and species distribution in soil profile were also assessed. Arbuscular mycorrhiza (AM) and DSE were found in D. cespitosa roots at all investigated soil levels. However, mycorrhizal colonization in topsoil was extremely low with sporadically occurring arbuscules. AM parameters: frequency of mycorrhization of root fragments (F%), intensity of root cortex colonization (M%), intensity of colonization within individual mycorrhizal roots (m%), and arbuscule abundance in the root system (A%) were markedly higher at 20-40, 40-60 cm soil levels and differed in a statistically significant manner from AM parameters from 0-10 and 10-20 cm layers. Mycorrhizal colonization was negatively correlated with bioavailable Cd, Pb and Zn concentrations. The number of AMF spores in topsoil was verlow and increased with soil depth (20-40 and 40-60 cm). At the study area spores of three morphologically distinctive AMF species were found: Archaeospora trappei, Funneliformis mosseae and Scutellospora dipurpurescens. The fourth species Glomus tenue colonized roots of D. cespitosa and was observed in the root cortex at 20-40 and 40-60 soil depth, however, its spores were not found at the site

The Different Faces of Arabidopsis arenosa - A Plant Species for a Special Purpose

The following review article collects information on the plant species Arabidopsis arenosa. Thus far, A. arenosa has been known as a model species for autotetraploidy studies because, apart from diploid individuals, there are also tetraploid populations, which is a unique feature of this Arabidopsis species. In addition, A arenosa has often been reported in heavy metal-contaminated sites, where it occurs together with a closely related species A. halleri, a model plant hyperaccumulator of Cd and Zn. Recent studies have shown that several populations of A. arenosa also exhibit Cd and Zn hyperaccumulation. However, it is assumed that the mechanism of hyperaccumulation differs between these two Arabidopsis species. Nevertheless, this phenomenon is still not fully understood, and thorough research is needed. In this paper, we summarize the current state of knowledge regarding research on A. arenosa

Biominerals and waxes of Calamagrostis epigejos and Phragmites australis leaves from post-industrial habitats

Vascular plants are able to conduct biomineralization processes and collect synthesized compounds in their internal tissues or to deposit them on their epidermal surfaces. This mechanism protects the plant from fluctuations of nutrient levels caused by different levels of supply and demand for them. The biominerals reflect both the metabolic characteristics of a vascular plant species and the environmental conditions of the plant habitat. The SEM/EDX method was used to examine the surface and cross-sections of the Calamagrostis epigejos and Phragmites australis leaves from post-industrial habitats (coal and zinc spoil heaps). The results from this study have showed the presence of mineral objects on the surfaces of leaves of both grass species. The calcium oxalate crystals, amorphous calcium carbonate spheres, and different silica forms were also found in the inner tissues. The high variety of mineral forms in the individual plants of both species was shown. The waxes observed on the leaves of the studied plants might be the initializing factor for the crystalline forms and structures that are present. For the first time, wide range of crystal forms is presented for C. epigejos. The leaf samples of P. australis from the post-industrial areas showed an increased amount of mineral forms with the presence of sulfur

Arbuscular mycorrhiza of Deschampsia cespitosa (Poaceae) at different soil depths in highly metal-contaminated site in southern Poland

This study presents root colonization of Deschampsia cespitosa growing in the immediate vicinity of a former Pb/Zn smelter by arbuscular mycorhizal fungi (AMF) and dark septated endophytes (DSE) at different soil depths. AMF spores and species distribution in soil profile were also assessed. Arbuscular mycorrhiza (AM) and DSE were found in D. cespitosa roots at all investigated soil levels. However, mycorrhizal colonization in topsoil was extremely low with sporadically occurring arbuscules. AM parameters: frequency of mycorrhization of root fragments (F%), intensity of root cortex colonization (M%), intensity of colonization within individual mycorrhizal roots (m%), and arbuscule abundance in the root system (A%) were markedly higher at 20–40, 40–60 cm soil levels and differed in a statistically significant manner from AM parameters from 0–10 and 10–20 cm layers. Mycorrhizal colonization was negatively correlated with bioavailable Cd, Pb and Zn concentrations. The number of AMF spores in topsoil was very low and increased with soil depth (20–40 and 40–60 cm). At the study area spores of three morphologically distinctive AMF species were found: Archaeospora trappei, Funneliformis mosseae and Scutellospora dipurpurescens. The fourth species Glomus tenue colonized roots of D. cespitosa and was observed in the root cortex at 20–40 and 40–60 soil depth, however, its spores were not found at the site

Photosynthetic Efficiency as Bioindicator of Environmental Pressure in A. halleri

In earlier ecophysiological studies that were conducted on Arabidopsis halleri plants, scientists focused on the mechanisms of Cd and Zn hyperaccumulation but did not take into consideration the environmental factors that can significantly affect the physiological responses of plants in situ. In this study, we investigated A. halleri that was growing on two nonmetalliferous and three metalliferous sites, which were characterized by different environmental conditions. We compared these populations in order to find differences within the metallicolous and nonmetallicolous groups that have not yet been investigated. The concentrations of several elements in the plant and soil samples also were investigated. To our knowledge, the concentration and fluorescence of chlorophyll were measured for A. halleri in situ for the first time. Our study confirmed the hyperaccumulation of Cd and Zn for each metallicolous population. For the metallicolous populations, the inhibition of parameters that describe the efficiency of the photosynthetic apparatus with increasing accumulations of heavy metals in the shoots also was observed. It was found that the nonmetallicolous plant populations from the summit of Ciemniak Mountain had larger antenna dimensions and chlorophyll content but a lower percentage of active reaction centers. To our knowledge, in this study, the internal high physiological diversity within the populations that inhabit metalliferous and nonmetalliferous sites is presented for the first time

Pobieranie i transport jonów azotanowych w roślinach oraz ich wpływ na architekturę korzeni

In response to varied availability of nitrogen in the soil plants developed mechanisms to improve the efficiency of uptake of this element, in particular several NO3 – transport systems. These transport systems belong to the following protein families: NPF (formerly NRT1), NRT2, CLC and SLAC1. NPF (symporters) are active when the NO3 - concentration in the environment is higher than 0,5 mmol · dm–3 and due to its low specifity for nitrate ions it also may transport other substrates such as e.g. amino acids. NRT2 protein family (symporters) transports nitrates and operates only when the external NO3 – concentrations are below 0,5 mmol · dm–3. SLAC1 proteins (anion channels) are located in the guard cells and are involved in the efflux of chloride and nitrate ions during the closing of stomata. CLC family apart from transporting Cl– has a high affinity for NO3 –. One of the members of these proteins, CLCa, is located in the tonoplast and is involved in the transport of nitrate ions to the vacuole in antiport with protons. After uptake by root cells, nitrate ions are distributed to various tissues and organs of the plant due to activity of other transporters belonging to the above-mentioned protein families. One of the most visible changes in response to the diverse resources of nitrates is a change in the architecture of roots. High concentrations of NO3 – (50 mmol · dm–3) in a substrate cause inhibition of branching of the root system. In the case of limited availability of nitrates (0,01 mmol · dm–3) stimulation of lateral root development occurs towards soil areas with higher NO3 - content (1,0 mmol · dm–3). In A. thaliana modifications of roots architecture occur without significant alteration in the biomass of roots, because the development of laterals is balanced by shortening of the main root. The low content of nitrate ions is a signal to expand the root system, while a high content of this ions is the signal to develop shoots

Hormesis in Plants: The Role of Oxidative Stress, Auxins and Photosynthesis in Corn Treated with Cd or Pb

Hormesis, which describes the stimulatory effect of low doses of toxic substances on growth, is a well-known phenomenon in the plant and animal kingdoms. However, the mechanisms that are involved in this phenomenon are still poorly understood. We performed preliminary studies on corn coleoptile sections, which showed a positive correlation between the stimulation of growth by Cd or Pb and an increase in the auxin and H2O2 content in the coleoptile sections. Subsequently, we grew corn seedlings in hydroponic culture and tested a wide range of Cd or Pb concentrations in order to determine hormetic growth stimulation. In these seedlings the gas exchange and the chlorophyll a fluorescence, as well as the content of chlorophyll, flavonol, auxin and hydrogen peroxide, were measured. We found that during the hormetic stimulation of growth, the response of the photosynthetic apparatus to Cd and Pb differed significantly. While the application of Cd mostly caused a decrease in various photosynthetic parameters, the application of Pb stimulated some of them. Nevertheless, we discovered that the common features of the hormetic stimulation of shoot growth by heavy metals are an increase in the auxin and flavonol content and the maintenance of hydrogen peroxide at the same level as the control plants

Toxic Effects of Cd and Zn on the Photosynthetic Apparatus of the Arabidopsis halleri and Arabidopsis arenosa Pseudo-Metallophytes

Hyperaccumulation and hypertolerance of Trace Metal Elements (TME) like Cd and Zn are highly variable in pseudo-metallophytes species. In this study we compared the impact of high Cd or Zn concentration on the photosynthetic apparatus of the Arabidopsis arenosa and Arabidopsis halleri pseudo-metallophytes growing on the same contaminated site in Piekary Slaskie in southern Poland. Plants were grown in hydroponic culture for 6 weeks, and then treated with 1.0 mM Cd or 5.0 mM Zn for 5 days. Chlorophyll a fluorescence and pigment content were measured after 0, 1, 2, 3, 4, and 5 days in plants grown in control and exposed to Cd or Zn treatments. Moreover, the effect of TME excess on the level of oxidative stress and gas-exchange parameters were investigated. In both plant species, exposure to high Cd or Zn induced a decrease in chlorophyll and an increase in anthocyanin contents in leaves compared to the control condition. After 5 days Cd treatment, energy absorbance, trapped energy flux and the percentage of active reaction centers decreased in both species. However, the dissipated energy flux in the leaves of A. arenosa was smaller than in A. halleri. Zn treatment had more toxic effect than Cd on electron transport in A. halleri compared with A. arenosa. A. arenosa plants treated with Zn excess did not react as strongly as in the Cd treatment and a decrease only in electron transport flux and percentage of active reaction centers compared with control was observed. The two species showed contrasting Cd and Zn accumulation. Cd concentration was almost 3-fold higher in A. arenosa leaves than in A. halleri. On the opposite, A. halleri leaves contained 3-fold higher Zn concentration than A. arenosa. In short, our results showed that the two Arabidopsis metallicolous populations are resistant to high Cd or Zn concentration, however, the photosynthetic apparatus responded differently to the toxic effects.Narodowe Centrum Nauk

Research on Arabidopsis arenosa and Arabidopsis halleri growing at site highly contaminated with heavy metals in southern Poland

Przeprowadzone badania miały na celu porównanie akumulacji Cd i Zn oraz stanu fizjologicznego u A. arenosa i A. halleri rosnących na tym samym stanowisku zanieczyszczonym metalami ciężkimi. Uzyskane wyniki powinny pomóc w ustaleniu, czy A. arenosa może zostać sklasyfikowana jako hyperakumulator Cd i Zn