[Show abstract][Hide abstract] ABSTRACT: Phytoremediation is a plant based, cost effective technology to detoxify or stabilise contaminated soils. Fast growing, high biomass, perennial plants may be used not only in phytoremediation but also in energy production. Szarvasi-1 energy grass (Elymus elongatus subsp. ponticus cv. Szarvasi-1), a good candidate for this combined application, was grown in nutrient solution in order to assess its Cd, Cu, Ni, Pb and Zn accumulation and tolerance. Its shoot metal accumulation showed the order Pb < Ni < Cu ∼ Cd < Zn. In parallel with this, Pb and Ni had no or very little influence on the growth, dry matter content, chlorophyll concentration and transpiration of the plants. Cu and Cd treatment resulted in significant decreases in all these parameters that can be attributed to Fe plaque formation in the roots suggested by markedly increased Fe and Cu accumulation. This came together with decreased shoot and root Mn concentrations in both treatments while shoot Cu and Zn concentrations decreased under Cd and Cu exposure, respectively. Zn treatment had no effect or even slightly stimulated the plants. This may be due to a slight stimulation of Fe translocation and a very efficient detoxification mechanism. Based on the average 300 mg kg(-1) (dry mass) Zn concentration which is 0.03% of the shoot dry mass the variety is suggested to be classified as Zn accumulator.
[Show abstract][Hide abstract] ABSTRACT: Hydroponic culture was applied to compare the efficiency of K2EDTA and citrate in mobilizing Pb for accumulation in Agropyron elongatum cv. Szarvasi-1 and their effects on some physiological characteristics of the plants. The plants were grown in nutrient solutions containing 0, 10, and 100 microM Pb(NO3)2 combined with chelating agents added to the nutrient solutions after 21 days of growth, in 3 concentrations (0, 100, and 500 microM). The effects were measured after eight days. The energy grass proved to be greatly resistant to the treatments, as was reflected in the slight inhibition of growth, the resistance of the photosynthetic electron transport chain and the chlorophyll composition and the lack of change in the malone-dialdehyde content. Fundamental differences can be identified between the effects of EDTA and citrate. Citrate had only a little effect on the physiological parameters, which may be due to the strongly increasing lead accumulation with increasing concentration of Pb in the nutrient solution. Additionally, citrate ensured a higher biomass yield with higher shoot Pb accumulation compared to EDTA in almost all treatments. Concerning biomass reduction, 10 microM Pb applied together with K2EDTA has the most deleterious effects on energy grass. The effects correlated with the concentration of EDTA.
No preview · Article · Mar 2011 · International Journal of Phytoremediation
[Show abstract][Hide abstract] ABSTRACT: The effects of arsenate and arsenite on growth and transpiration were investigated in cucumber plants grown in nutrient solution containing 2, 10, and 100 μM phosphate, respectively. Root and shoot growth decreased by 48–64% compared to the control in all treatments and there was no significant difference between the effects of arsenic As(V) and As(III) except for the lowest phosphate concentration. At 2 μM phosphate As(III) had significantly higher growth inhibition than As(V). The inhibition of transpiration was between 46–68% in all treatments, and As(V) had stronger effect at 10 μM phosphate compared to 100 μM. Arsenic caused fast wilting 2 hours after the commencement of the treatment. However, the formation of adventitious roots prevented the loss of turgor. The hypothesis that aquaporins might be involved in the action of As(V) has been tested by comparison of the effect of As(V) and Hg, the inhibitor of aquaporins. Both treatments resulted in similar inhibition of growth and transpiration, increase in water saturation deficit and decrease in root exudation. Data imply that (i) phosphate reduces arsenate uptake, (ii) arsenate can be at least partially detoxified in cucumber at higher phosphate concentrations, (iii) arsenate may be reduced to arsenite and (iv) As(V) may interfere with the proper functioning of aquaporins.
No preview · Article · Jan 2011 · Journal of Plant Nutrition
[Show abstract][Hide abstract] ABSTRACT: The uptake and accumulation of iron in cucumber roots exposed to cadmium were investigated with Fe sufficient and deficient
cucumber plants using Mössbauer spectroscopy, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and ferric chelate reductase
activity measurements. Both Fe sufficient and Fe deficient plants were applied. In the case of Fe sufficient cucumber roots
grown in nutrient solution with 10μM Cd no changes were found in the occurrence of Fe species (mostly hydrous ferric oxides
and ferric-carboxylate complexes) compared to the control where no Cd was added. In the Fe deficient roots pretreated with
0, 0.1, 1, 10 and 100μM Cd for 3h then supplied also with 0.5mM 57Fe-citrate for 30min, FeII was identified in a hexaaqua complex form. The relative amount of FeII was decreasing simultaneously with increasing Cd concentration, while the relative occurrence of FeIII species and total Fe concentration were increasing. The results support the inhibitory effect of Cd on Fe-chelate reduction.
Although the reductase activity at 10 and 100μM Cd treatment was lower than in the iron sufficient control plants, FeII could be identified by Mössbauer spectroscopy whereas in the Fe sufficient control, this form was below detection limit.
These data demonstrate that the influx and the reoxidation of FeII was decreased by Cd, consequently, they refer to the competition of Cd2+ and Fe2+ during the membrane transport and the inhibition of the reoxidation process.
[Show abstract][Hide abstract] ABSTRACT: Iron uptake and distribution in wheat roots were studied with 57Fe Mössbauer spectroscopy. Plants were grown both in iron sufficient and in iron deficient nutrient solutions. Mössbauer spectra
of the frozen iron sufficient roots exhibited three iron(III) components with the typical average Mössbauer parameters of
δ = 0.50mm s − 1, Δ = 0.43mm s − 1, δ = 0.50mm s − 1, Δ = 0.75mm s − 1 and δ = 0.50mm s − 1, Δ = 1.20mm s − 1 at 80K. These doublets are very similar to those obtained earlier for cucumber , which allows us to suppose that iron
is stored in a very similar way in different plants. No ferrous iron could be identified in any case, not even in the iron
deficient roots, which confirms the mechanism proposed for iron uptake in the graminaceous plants.
[Show abstract][Hide abstract] ABSTRACT: Senescence and rejuvenation were investigated in detached cucumber (Cucumis sativus L.) leaves after cultivation in nutrient solution for one week or four weeks. Rooting of the petiole (visible generally from the 7th day) elicited a combination of different morphological, anatomical, and physiological changes in the lamina. Extensive growth in area and thickness, extreme regreening, changes of chloroplast structure and activity, as well as the pattern of Chl-protein complexes were observed and compared either to the corresponding parameters of young detached leaves or mature attached leaves. These responses could be provoked separately by treating excised leaf discs with kinetin, benzyladenine, or indolylacetic acid. The hormones showed mutuality in their effects, benzyladenine being responsible for the growth of cells, while indolylacetic acid and kinetin promoted an increase in chlorophyll content. However, none of the treatments resulted in the growth of the chloroplasts in the leaf discs, which was only prominent in the rooting leaves.
[Show abstract][Hide abstract] ABSTRACT: Flow injection analysis (FIA) and high-performance liquid chromatography double-focusing sector field inductively coupled plasma mass spectrometry (HPLC-DF-ICP-MS) were used for total arsenic determination and arsenic speciation of xylem sap of cucumber plants (Cucumis sativus L.) grown in hydroponics containing 2 micromol dm(-3) arsenate or arsenite, respectively. Arsenite [As(III)], arsenate [As(V)] and dimethylarsinic acid (DMA) were identified in the sap of the plants. Arsenite was the predominant arsenic species in the xylem saps regardless of the type of arsenic treatment, and the following concentration order was determined: As(III) > As(V) > DMA. The amount of total As, calculated taking into consideration the mass of xylem sap collected, was almost equal for both treatments. Arsenite was taken up more easily by cucumber than arsenate. Partial oxidation of arsenite to arsenate (<10% in 48 h) was observed in the case of arsenite-containing nutrient solutions, which may explain the detection of arsenate in the saps of plants treated with arsenite.
No preview · Article · Oct 2005 · Analytical and Bioanalytical Chemistry
[Show abstract][Hide abstract] ABSTRACT: Effects of 10 microM cadmium (supplied as Cd nitrate) on the utilization and allocation of iron (Fe) were investigated in poplar (Populus alba L.) plants grown in nutrient solution with Fe(III)-EDTA or Fe(III)-citrate as the Fe source. The effects of Cd were also compared with those of Fe deprivation. The accumulation of Fe in roots was 10-fold higher in plants grown with Fe-citrate than with Fe-EDTA. Cadmium decreased leaf chlorophyll concentrations and photosynthetic rates, and these decreases were more marked in plants grown with Fe-citrate than with Fe-EDTA. In both Fe treatments, addition of Cd caused large increases in root and shoot apoplasmic and non-apoplasmic Cd contents and increases in root Fe content; however, Cd decreased shoot Fe content, especially in plants grown with Fe-citrate. New leaves of plants grown with Fe-citrate had small cellular (non-apoplasmic) Fe pools, whereas these pools were large in new leaves of plants grown with Fe-EDTA. Non-apoplasmic Cd pools in new leaves were smaller in plants grown with Fe-citrate than with Fe-EDTA, indicating that inactivation of non-apoplasmic Cd pools is facilitated more by Fe-EDTA than by Fe-citrate. In the presence of Cd, Fe-EDTA was also superior to Fe-citrate in maintaining an adequate Fe supply to poplar shoots. Differences in plant responses to Fe-EDTA and Fe-citrate may reflect differences in long-distance transport of Fe rather than in acquisition of Fe by roots.
[Show abstract][Hide abstract] ABSTRACT: Heavy metals can disrupt plant metabolism, including photosynthesis, in a number of different ways. One common mechanism in acclimation of plants to abiotic stresses is the accumulation of compatible solutes. In these study we analysed the effect of exogenously added phosphonomethyl-sarcosine, a derivative of a synthesis intermedier of glycinebetaine, on leaf development in poplar under Cu and Cd stress. While growth was more strongly reduced by Cu treatment, Cd preferably inhibited photosynthesis. These effects were connected to the disturbed water (Cu stress) and ion balance (Cd stress) of plants. The symptoms of Cu and Cd stress were totally and partially abolished by exogenously added phosphonomethyl-sarcosine, respectively. Its protective effect might be based on the complexation of heavy metals (Cu stress), but glycinebetaine-like macromolecule/membrane protecting effects (Cd stress) are also possible.
No preview · Article · Jan 2005 · Acta Biologica Szegediensis
[Show abstract][Hide abstract] ABSTRACT: Pb (10 to 100 μM) effects on the development of thylakoids were investigated in Fe-EDTA and Fe-citrate grown cucumber and poplar to compare the symptoms in different plant species. Increased chlorophyll content of leaves appeared either in PSII core or LHCII depending on the treatment. Lowering of the chlorophyll content, however, was accompanied by decrease in PSI and LHCII, and relatively high stability of PSII core. PSII efficiency and CO2 fixation were mostly unchanged or decreased moderately, but rise in the non-photochemical quenching was observed in all kinds of treatment. While Pb could not be detected and Mn content decreased in poplar leaves, changes in photosynthetic parameters paralleled with the Pb content in cucumber, and increase in Fe, Mn, and Ca content was measured. The direct effects of Pb or oxidative stress may evoke the changes in cucumber, while Pb induced Mn deficiency seems to play a role in poplar. Alterations in the composition of thylakoids were probably triggered by regulatory processes, which optimise the structure and function under stress conditions.
No preview · Article · Jan 2002 · Acta Biologica Szegediensis
[Show abstract][Hide abstract] ABSTRACT: Total-reflection X-ray fluorescence (TXRF) spectrometry, reversed-phase (RP) and size–exclusion (SE) high-performance liquid chromatography (HPLC) methods were applied for the characterization of low-volume xylem sap of control and nickel contaminated cucumber plants growing in hydroponics containing urea as the sole nitrogen source. In these saps collected for 1 h, Ca, K, Fe, Mn, Ni, Zn, as well as malic, citric and fumaric acids were determined. The SEC measurements showed that macromolecules were not detectable in the samples. Nickel contamination had minimum impact on the organic acid transport, however, the transport of Zn, K and Fe was reduced by 50, 22 and 11%, respectively. This observation supports the results of our earlier experiments when nitrate ions were used as the sole nitrogen form. At the same time, the fresh root weight and the volume of the collected xylem sap increased by 36 and 85%, respectively. Therefore, nickel addition seemed to decrease the urea toxicity of the plants. By pooling the eluting fractions of the SEC column, which were 10-fold concentrated by freeze-drying, the series of the resulted samples were analyzed by the TXRF spectrometry and RP-HPLC. The three organic acids could be identified in only one of the fractions, which contained Fe and, in the case of the contaminated plants, Ni in detectable concentration. However, considerable parts of these two elements and Mn, as well as practically the total amounts of Cu may be transported by unidentified organic compounds in the xylem.
No preview · Article · Nov 2001 · Spectrochimica Acta Part B Atomic Spectroscopy
[Show abstract][Hide abstract] ABSTRACT: An 'off-line' high performance liquid chromatography-graphite furnace atomic absorption spectrometry (HPLC-GF-AAS) method using a size exclusion chromatography (SEC) column was developed to investigate heavy metal ions in xylem sap samples of cucumber plants grown in hydroponics containing iron as Fe(III)-ethylenediaminetetraacetate (Fe(III) EDTA), Fe(III) citrate or FeCl3 and exposed to lead, nickel or vanadium contamination. The SEC chromatogram of the samples contained the peak of nitrate ions (in significant concentration approximately 1400 microg/ml) and some small, unidentified compounds with molecular weight lower than 700 Da. The results indicate that Cu and Mn--which were added to the hydroponics as nutrient elements--determined in the collected fractions during the chromatographic runs are transported in the xylem vessels together with small inorganic ions like nitrate ions. In case of nickel other low-molecular weight compounds eluting earlier than the nitrate ions may take part in its transport toward the shoots. Lead could not be detected in the above mentioned fractions. Determination of vanadium in the fractions was not expected since it could not be detected in the sap samples.
No preview · Article · Aug 2000 · Journal of Inorganic Biochemistry
[Show abstract][Hide abstract] ABSTRACT: Several studies have demonstrated a consistently high sensitivity of dobutamine echocardiography whereas test specificity in these series has been variable. The aim of this study was to evaluate whether coronary vasospasm--elicited by alpha1 adrenoreceptor stimulation--may be a significant source of false positive responses during dobutamine stress.
From the data bank of four institutions we selected 113 patients (75 males, 38 females, mean age 55 +/- 12 years) with dobutamine echocardiography performed (up to 40 micrograms/kg/min and atropine 1 mg if needed) before a coronary angiography showing normal or near normal (visually assessed stenosis severity < 50%) coronary arteries. The following variables--which were previously reported influencing dobutamine echo specificity--entered the multivariate statistical analysis: age, sex, heart rate at baseline and at peak stress, baseline echo, hypertension, site of asynergy, and spasm at coronary angiography.
Twenty-five patients had a positive dobutamine test. The positivity occurred in the left coronary territory in 15 and in the right coronary territory in 10 cases. All the 6 patients with spontaneous spasm during angiography had a false positive stress test result. By multivariate analysis only coronary artery spasm during angiography (p = 0.0015) and history of hypertension (p = 0.0031) were significant predictors of false positive results of dobutamine stress echocardiography.
Coronary artery spasm may be an important source of false positive results during dobutamine stress echocardiography.
No preview · Article · Nov 1999 · Cardiologia (Rome, Italy)
[Show abstract][Hide abstract] ABSTRACT: Hydroponically cultured cucumber plants supplied with 4 μM Fe chelated either with EDTA or citrate and treated with Cd (10 μM) and Pb (10, 50 μM) from their one- or four-leaf stage were grown up to five-week-old age. The decrease in the chlorophyll content was the most pronounced in plants treated with Cd from a younger age, and in the case of Fe-citrate. The chlorophyll a/b ratio of Cd stressed plants was also significantly lowered. In later treated plants the accumulation of chlorophyll was inhibited and the chlorophyll a/b ratio decreased only in the vigorously growing young leaves. Pb treatment had only a slight effect on both parameters. The changes in the chlorophyll-protein pattern of thylakoids were strongly related to their chlorophyll content but the response of each complex was different. Cd reduced the amount of chlorophyll containing complexes in the order of photosystem I > light-harvesting complex II > photosystem II-core, while light-harvesting complex II appeared somewhat more sensitive than photosystem I in Pb treated plants. In accordance, a decline or blue shift of the long wavelength fluorescence emission band of chloroplasts was observed referring to disturbances also in photosystem I antenna assembly. The accumulation of chlorophyll and chlorophyll-proteins did not show close relationship to the heavy metal content of leaves which was the highest in the first of the intensively expanding leaves in the time of the treatment. The extraordinary sensitivity of photosystem I, and the relative stability of photosystem II under Cd treatment were similar to the case found in iron deficient plants. However, the pattern of chlorophyll content of leaf storeys of Cd treated plants rather followed the changes in their Mn content.
[Show abstract][Hide abstract] ABSTRACT: Three organic acids (citric, fumaric and malic) of the Krebs cycle were measured by the reversed-phase high performance liquid chromatography (RP-HPLC) technique in the xylem saps of cucumber plants grown in (i) control nutrient solutions containing iron as Fe(III)-ethylene-diamine-tetraacetate (Fe(III)-EDTA), Fe(III)-citrate or FeCl3 and (ii) in nutrient solutions contaminated with nickel, lead or vanadium in a concentration of 10−5 M. Simultaneously, the heavy metal content of the xylem sap samples was determined by total reflection X-ray fluorescence spectrometry (TXRF). In the presence of lead or nickel contamination the transport of the organic acids became higher by factor 1.1–2.3 compared to the control plants when Fe(III)-citrate or Fe(III)-chloride was added to the nutrient solutions. In the case of plants growing in Fe(III)-EDTA containing solutions, however, the transport of the organic acids decreased by 30–40%. The effect of vanadium on the transport of organic acids was considerably smaller. Generally, the deviation in the organic acid transport between the contaminated and the control plants was proportional to the heavy metal transport in the xylem in the sequence Ni>Pb>V.
No preview · Article · Jun 1999 · Journal of Inorganic Biochemistry
[Show abstract][Hide abstract] ABSTRACT: Mobility and distribution of lead (Pb) were investigated in cucumber (Cucumis sativus L.) grown in solution culture. Based on the observation that Pb uptake is influenced by the chemical form of iron (Fe) (complexed or ionic) in the solution, Fe distribution was also determined. Iron concentration was even in the stem (separated to internodes) and petioles but slightly increased at the shoot tip while Pb concentration decreased upwards. In the leaves Fe concentration decreased upwards (whereas in the control it increased a little at the youngest leaves) while Pb concentration increased to the largest leaves then decreased towards the shoot tip. It is suggested that the distribution of Pb in cucumber is passive process and it accumulates in the apoplast while Fe distribution is determined by the requirements of synthetic processes in young or photosynthesizing tissues. Lead probably lowers Fe transport into the symplast in the leaves causing slight chlorosis at the youngest leaves. In the plants that were loaded with Pb, decapitated and rooted again in Pb‐free culture solution we found no significant remobilization of Pb which supports that Pb binds strongly to the binding sites in the apoplast or is detoxified in an immobile form.
No preview · Article · Jul 1998 · Journal of Plant Nutrition