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1

Large Expression Differences in Genes for Iron and Zinc Homeostasis, Stress Response, and Lignin Biosynthesis Distinguish Roots of Arabidopsis thaliana and the Related Metal Hyperaccumulator Thlaspi caerulescens1[W  

PubMed Central

The micronutrient zinc has an essential role in physiological and metabolic processes in plants as a cofactor or structural element in 300 catalytic and noncatalytic proteins, but it is very toxic when available in elevated amounts. Plants tightly regulate their internal zinc concentrations in a process called zinc homeostasis. The exceptional zinc hyperaccumulator species Thlaspi caerulescens can accumulate up to 3% of zinc, but also high amounts of nickel and cadmium, without any sign of toxicity. This should have drastic effects on the zinc homeostasis mechanism. We examined in detail the transcription profiles of roots of Arabidopsis thaliana and T. caerulescens plants grown under deficient, sufficient, and excess supply of zinc. A total of 608 zinc-responsive genes with at least a 3-fold difference in expression level were detected in A. thaliana and 352 in T. caerulescens in response to changes in zinc supply. Only 14% of these genes were also zinc responsive in A. thaliana. When comparing A. thaliana with T. caerulescens at each zinc exposure, more than 2,200 genes were significantly differentially expressed (?5-fold and false discovery rate < 0.05). While a large fraction of these genes are of yet unknown function, many genes with a different expression between A. thaliana and T. caerulescens appear to function in metal homeostasis, in abiotic stress response, and in lignin biosynthesis. The high expression of lignin biosynthesis genes corresponds to the deposition of lignin in the endodermis, of which there are two layers in T. caerulescens roots and only one in A. thaliana.

van de Mortel, Judith E.; Almar Villanueva, Laia; Schat, Henk; Kwekkeboom, Jeroen; Coughlan, Sean; Moerland, Perry D.; Ver Loren van Themaat, Emiel; Koornneef, Maarten; Aarts, Mark G.M.

2006-01-01

2

Decrease of labile Zn and Cd in the rhizosphere of hyperaccumulating Thlaspi caerulescens with time.  

PubMed

By using a rhizobox micro-suction cup technique we studied in-situ mobilization and complexation of Zn and Cd in the rhizosphere of non-hyperaccumulating Thlaspi perfoliatum and two different Thlaspi caerulescens ecotypes, one of them hyperaccumulating Zn, the other Zn and Cd. The dynamic fraction (free metal ions and small labile complexes) of Zn and Cd decreased with time in the rhizosphere solution of the respective hyperaccumulating T. caerulescens ecotypes, and at the end of the experiment, it was significantly smaller than in the other treatments. Furthermore, the rhizosphere solutions of the T. caerulescens ecotypes exhibited a higher UV absorptivity than the solution of the T. perfoliatum rhizosphere and the plant-free soil. Based on our findings we suggest that mobile and labile metal-dissolved soil organic matter complexes play a key role in the rapid replenishment of available metal pools in the rhizosphere of hyperaccumulating T. caerulescens ecotypes, postulated earlier. PMID:19913965

Dessureault-Rompré, Jacynthe; Luster, Jörg; Schulin, Rainer; Tercier-Waeber, Mary-Lou; Nowack, Bernd

2009-11-13

3

Investigating Heavy-metal Hyperaccumulation using Thlaspi caerulescens as a Model System  

PubMed Central

Background Metal-hyperaccumulating plant species are plants that are endemic to metalliferous soils and are able to tolerate and accumulate metals in their above-ground tissues to very high concentrations. One such hyperaccumulator, Thlaspi caerulescens, has been widely studied for its remarkable properties to tolerate toxic levels of zinc (Zn), cadmium (Cd) and sometimes nickel (Ni) in the soil, and accumulate these metals to very high levels in the shoot. The increased awareness regarding metal-hyperaccumulating plants by the plant biology community has helped spur interest in the possible use of plants to remove heavy metals from contaminated soils, a process known as phytoremediation. Hence, there has been a focus on understanding the mechanisms that metal-hyperaccumulator plant species such as Thlaspi caerulescens employ to absorb, detoxify and store metals in order to use this information to develop plants better suited for the phytoremediation of metal-contaminated soils. Scope In this review, an overview of the findings from recent research aimed at better understanding the physiological mechanisms of Thlaspi caerulescens heavy-metal hyperaccumulation as well as the underlying molecular and genetic determinants for this trait will be discussed. Progress has been made in understanding some of the fundamental Zn and Cd transport physiology in T. caerulescens. Furthermore, some interesting metal-related genes have been identified and characterized in this plant species, and regulation of the expression of some of these genes may be important for hyperaccumulation. Conclusions Thlaspi caerulescens is a fascinating and useful model system not only for studying metal hyperaccumulation, but also for better understanding micronutrient homeostasis and nutrition. Considerable future research is still needed to elucidate the molecular, genetic and physiological bases for the extreme metal tolerance and hyperaccumulation exhibited by plant species such as T. caerulescens.

Milner, Matthew J.; Kochian, Leon V.

2008-01-01

4

Hyperaccumulation of cadmium by hairy roots of Thlaspi caerulescens  

SciTech Connect

Hairy roots were used to investigate cadmium uptake by Thlaspi caerulescens, a metal hyperaccumulator plant with potential applications in phytoremediation and phytomining. Experiments were carried out in nutrient media under conditions supporting root growth. Accumulation of Cd in short-term (9-h) experiments varied with initial medium pH and increased after treating the roots with H{sup +}-ATPase inhibitor. The highest equilibrium Cd content measured in T. caerulescens roots was 62,800 {micro}g g{sup {minus}1} dry weight, or 6.3% dry weight, at a liquid Cd concentration of 3,710 ppm. Cd levels in live T. caerulescens roots were 1.5- to 1.7-fold those in hairy roots of nonhyperaccumulator species exposed to the same Cd concentration, but similar to the Cd content of auto-claved T. caerulescens roots. The ability to grow at Cd concentrations of up to 100 ppm clearly distinguished T. caerulescens hairy roots from the nonhyperaccumulators. The specific growth rate of T. caerulescens roots was essentially unaffected by 20 to 50 ppm Cd in the culture medium; in contrast, N. tabacum roots turned dark brown at 20 ppm and growth was negligible. Up to 10,600 {micro}g g{sup {minus}1} dry weight Cd was accumulated by growing T. caerulescens hairy roots. Measurement of Cd levels in while roots and in the cell wall fraction revealed significant differences in the responses of T. caerulescens and N. tabacum roots to 20 ppm Cd. Most metal was transported directly into the symplasm of N. tabacum roots within 3 days of exposure; in contrast, T. caerulescens roots stored virtually all of their Cd in the wall fraction for the first 7 to 10 days. This delay in transmembrane uptake may represent an important defensive strategy against Cd poisoning in T. caerulescens, allowing time for activation of intracellular mechanisms for heavy metal detoxification.

Nedelkoska, T.V.; Doran, P.M.

2000-03-05

5

CHARACTERIZATION OF ZINC TOLERANCE GENES IN THE ZINC/CADMIUM HYPERACCUMULATOR, THLASPI CAERULESCENS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Thlaspi caerulescens, a heavy metal hyperaccumulating plant species, accumulates up to 30,000 ppm zinc in the above ground biomass without exhibiting toxicity symptoms. Previous work in our lab has shown that altered regulation of micronutrient uptake, transport and sequestration in this species pla...

6

The Role of Metal Transport and Tolerance in Nickel Hyperaccumulation by Thlaspi goesingense Halacsy.  

PubMed Central

Metal hyperaccumulators are plants that are capable of extracting metals from the soil and accumulating them to extraordinary concentrations in aboveground tissues (greater than 0.1% dry biomass Ni or Co or greater than 1% dry biomass Zn or Mn). Approximately 400 hyperaccumulator species have been identified, according to the analysis of field-collected specimens. Metal hyperaccumulators are interesting model organisms to study for the development of a phytoremediation technology, the use of plants to remove pollutant metals from soils. However, little is known about the molecular, biochemical, and physiological processes that result in the hyperaccumulator phenotype. We investigated the role of Ni tolerance and transport in Ni hyperaccumulation by Thlaspi goesingense, using plant biomass production, evapotranspiration, and protoplast viability assays, and by following short- and long-term uptake of Ni into roots and shoots. As long as both species (T. goesingense and Thlaspi arvense) were unaffected by Ni toxicity, the rates of Ni translocation from roots to shoots were the same in both the hyper- and nonaccumulator species. Our data suggest that Ni tolerance is sufficient to explain the Ni hyperaccumulator phenotype observed in hydroponically cultured T. goesingense when compared with the Ni-sensitive nonhyperaccumulator T. arvense.

Kramer, U.; Smith, R. D.; Wenzel, W. W.; Raskin, I.; Salt, D. E.

1997-01-01

7

Gene Manipulation of a Heavy Metal Hyperaccumulator Species Thlaspi caerulescens L. via Agrobacterium -mediated Transformation  

Microsoft Academic Search

Thlaspi caerulescens L. is well known as a Zn\\/Cd hyperaccumulator. The genetic manipulation of T. caerulescens through transgenic technology can modify plant features for use in phytoremediation. Here, we describe the efficient transformation\\u000a of T. caerulescens using Agrobacterium tumefaciens strain EHA105 harboring a binary vector pBI121 with the nptII gene as a selectable marker, the gus gene as a reporter and a

Zi Qiu Guan; Tuan Yao Chai; Yu Xiu Zhang; Jin Xu; Wei Wei; Lu Han; Lin Cong

2008-01-01

8

ROOTS OF METAL HYPERACCUMULATING POPULATION OF THLASPI PRAECOX (BRASSICACEAE) HARBOUR ARBUSCULAR MYCORRHIZAL AND OTHER FUNGI UNDER EXPERIMENTAL CONDITIONS  

Microsoft Academic Search

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%,

Paula Pongrac; Silva Sonjak; Katarina Vogel-Mikuš; Peter Kump; Marijan Ne?emer; Marjana Regvar

2009-01-01

9

Altered Zn Compartmentation in the Root Symplasm and Stimulated Zn Absorption into the Leaf as Mechanisms Involved in Zn Hyperaccumulation in Thlaspi caerulescens  

Microsoft Academic Search

We investigated Zn compartmentation in the root, Zn transport into the xylem, and Zn absorption into leaf cells in Thlaspi caerule- scens, a Zn-hyperaccumulator species, and compared them with those of a related nonaccumulator species, Thlaspi arvense. 65Zn- compartmental analysis conducted with roots of the two species indicated that a significant fraction of symplasmic Zn was stored in the root

Mitch M. Lasat; Alan J. M. Baker; Leon V. Kochian

1998-01-01

10

Gene manipulation of a heavy metal hyperaccumulator species Thlaspi caerulescens L. via Agrobacterium-mediated transformation.  

PubMed

Thlaspi caerulescens L. is well known as a Zn/Cd hyperaccumulator. The genetic manipulation of T. caerulescens through transgenic technology can modify plant features for use in phytoremediation. Here, we describe the efficient transformation of T. caerulescens using Agrobacterium tumefaciens strain EHA105 harboring a binary vector pBI121 with the nptII gene as a selectable marker, the gus gene as a reporter and a foreign catalase gene. Based on the optimal concentration of growth regulators, the shoot cluster regeneration system via callus phase provided the basis of the genetic transformation in T. caerulescens. The key variables in transformation were examined, such as co-cultivation period and bacterial suspension density. Optimizing factors for T-DNA delivery resulted in kanamycin-resistant transgenic shoots with transformation efficiency more than 20%, proven by histochemical GUS assay and PCR analysis. Southern analysis of nptII and RT-PCR of catalase gene demonstrated that the foreign genes were integrated in the genome of transformed plantlets. Moreover, the activity of catalase enzyme in transgenic plants was obviously higher than in wild-type plants. This method offers new prospects for the genetic engineering of this important hyperaccumulator species. PMID:18427996

Guan, Zi Qiu; Chai, Tuan Yao; Zhang, Yu Xiu; Xu, Jin; Wei, Wei; Han, Lu; Cong, Lin

2008-04-22

11

Cadmium-induced inhibition of photosynthesis and long-term acclimation to cadmium stress in the hyperaccumulator Thlaspi caerulescens.  

PubMed

Acclimation of hyperaccumulators to heavy metal-induced stress is crucial for phytoremediation and was investigated using the hyperaccumulator Thlaspi caerulescens and the nonaccumulators T. fendleri and T. ochroleucum. Spatially and spectrally resolved kinetics of in vivo absorbance and fluorescence were measured with a novel fluorescence kinetic microscope. At the beginning of growth on cadmium (Cd), all species suffered from toxicity, but T. caerulescens subsequently recovered completely. During stress, a few mesophyll cells in T. caerulescens became more inhibited and accumulated more Cd than the majority; this heterogeneity disappeared during acclimation. Chlorophyll fluorescence parameters related to photochemistry were more strongly affected by Cd stress than nonphotochemical parameters, and only photochemistry showed acclimation. Cd acclimation in T. caerulescens shows that part of its Cd tolerance is inducible and involves transient physiological heterogeneity as an emergency defence mechanism. Differential effects of Cd stress on photochemical vs nonphotochemical parameters indicate that Cd inhibits the photosynthetic light reactions more than the Calvin-Benson cycle. Differential spectral distribution of Cd effects on photochemical vs nonphotochemical quenching shows that Cd inhibits at least two different targets in/around photosystem II (PSII). Spectrally homogeneous maximal PSII efficiency (F(v)/F(m)) suggests that in healthy T. caerulescens all chlorophylls fluorescing at room temperature are PSII-associated. PMID:17688582

Küpper, Hendrik; Parameswaran, Aravind; Leitenmaier, Barbara; Trtílek, Martin; Setlík, Ivan

2007-01-01

12

Hyperaccumulation of Cadmium and Zinc in Thlaspi caerulescens and Arabidopsis halleri at the Leaf Cellular Level1  

PubMed Central

Vacuolar compartmentalization or cell wall binding in leaves could play a major role in hyperaccumulation of heavy metals. However, little is known about the physiology of intracellular cadmium (Cd) sequestration in plants. We investigated the role of the leaf cells in allocating metal in hyperaccumulating plants by measuring short-term 109Cd and 65Zn uptake in mesophyll protoplasts of Thlaspi caerulescens “Ganges” and Arabidopsis halleri, both hyperaccumulators of zinc (Zn) and Cd, and T. caerulescens “Prayon,” accumulating Cd at a lower degree. The effects of low temperature, several divalent cations, and pre-exposure of the plants to metals were investigated. There was no significant difference between the Michaelis-Menten kinetic constants of the three plants. It indicates that differences in metal uptake cannot be explained by different constitutive transport capacities at the leaf protoplast level and that plasma and vacuole membranes of mesophyll cells are not responsible for the differences observed in heavy metal allocation. This suggests the existence of regulation mechanisms before the plasma membrane of leaf mesophyll protoplasts. However, pre-exposure of the plants to Cd induced an increase in Cd accumulation in protoplasts of “Ganges,” whereas it decreased Cd accumulation in A. halleri protoplasts, indicating that Cd-permeable transport proteins are differentially regulated. The experiment with competitors has shown that probably more than one single transport system is carrying Cd in parallel into the cell and that in T. caerulescens “Prayon,” Cd could be transported by a Zn and Ca pathway, whereas in “Ganges,” Cd could be transported mainly by other pathways.

Cosio, Claudia; Martinoia, Enrico; Keller, Catherine

2004-01-01

13

Cellular Compartmentation of Zinc in Leaves of the Hyperaccumulator Thlaspi caerulescens  

Microsoft Academic Search

Cellular compartmentation of Zn in the leaves of the hyperaccu- mulator Thlaspi caerulescens was investigated using energy- dispersive x-ray microanalysis and single-cell sap extraction. Energy-dispersive x-ray microanalysis of frozen, hydrated leaf tis- sues showed greatly enhanced Zn accumulation in the epidermis compared with the mesophyll cells. The relative Zn concentration in the epidermal cells correlated linearly with cell length in

Hendrik Kupper; Fang Jie Zhao; Steve P. McGrath

1999-01-01

14

FURTHER CHARACTERIZATION OF ZINC TOLERANCE GENES FROM THE ZINC/CADMIUM HYPERACCUMULATOR THLASPI CAERULESCENS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The uptake of plant micronutrients requires a well-honed regulatory system that can accumulate adequate levels of these scarce metals for growth yet avoids accumulation to toxic concentrations. In hyperaccumulating plant species, this micronutrient homeostasis is altered resulting in plants that can...

15

TcOPT3, a Member of Oligopeptide Transporters from the Hyperaccumulator Thlaspi caerulescens, Is a Novel Fe/Zn/Cd/Cu Transporter  

PubMed Central

Background Thlaspi caerulescens is a natural selected heavy metal hyperaccumulator that can not only tolerate but also accumulate extremely high levels of heavy metals in the shoots. Thus, to identify the transportors involved in metal long-distance transportation is very important for understanding the mechanism of heavy metal accumulation in this hyperaccumulator. Methodology/Principal Findings We cloned and characterized a novel gene TcOPT3 of OPT family from T. caerulescens. TcOPT3 was pronouncedly expressed in aerial parts, including stem and leaf. Moreover, in situ hybridization analyses showed that TcOPT3 expressed in the plant vascular systems, especially in the pericycle cells that may be involved in the long-distance transportation. The expression of TcOPT3 was highly induced by iron (Fe) and zinc (Zn) deficiency, especially in the stem and leaf. Sub-cellular localization showed that TcOPT3 was a plasma membrane-localized protein. Furthermore, heterogonous expression of TcOPT3 by mutant yeast (Saccharomyces cerevisiae) complementation experiments demonstrated that TcOPT3 could transport Fe2+ and Zn2+. Moreover, expression of TcOPT3 in yeast increased metal (Fe, Zn, Cu and Cd) accumulation and resulted in an increased sensitivity to cadmium (Cd) and copper (Cu). Conclusions Our data demonstrated that TcOPT3 might encode an Fe/Zn/Cd/Cu influx transporter with broad-substrate. This is the first report showing that TcOPT3 may be involved in metal long-distance transportation and contribute to the heavy metal hyperaccumulation.

Hu, Yi Ting; Ming, Feng; Chen, Wei Wei; Yan, Jing Ying; Xu, Zheng Yu; Li, Gui Xin; Xu, Chun Yan; Yang, Jian Li; Zheng, Shao Jian

2012-01-01

16

Cd induced redistribution of elements within leaves of the Cd/Zn hyperaccumulator Thlaspi praecox as revealed by micro-PIXE  

NASA Astrophysics Data System (ADS)

A detailed localisation of elements within leaf tissues of hydroponically grown Cd/Zn hyperaccumulator Thlaspi praecox (Brassicaceae) was determined by micro-PIXE at Jožef Stefan Institute (Ljubljana, Slovenia) in order to study accumulation patterns of Cd and other elements in the case of a single metal (Cd) pollution. Plants were treated with increasing concentrations of Cd in the solution (0 (control), 1, 10 and 100 ?M). As expected, concentration of Cd in the leaves gradually increased with Cd concentration in the solution. In order to reveal the main Cd storage compartment space within the leaves a relative element distribution (pool) was calculated based on concentrations of elements in specific leaf tissues and their weight portions. Where present at detectable levels, Cd accumulated in the epidermal tissues (at 10 ?M), but the contribution of epidermal pool decreased with increasing Cd concentration in solution (at 100 ?M). The opposite was observed for the mesophyll pool. In addition, in Cd treated plants, a significant decrease in mesophyll Fe pool and an increase in the epidermal Fe pool were observed. Similar effect was seen for Mn pool at 100 ?M Cd treatment accompanied by increasing Zn epidermal pool with increasing Cd in nutrient solution. Altogether these results indicate repartitioning of essential mesophyll cation pools (e.g., Fe, Mn and possibly Zn) when increasing Cd contents, that are instead more intensively stored in the epidermal cells. These results confirmed micro-PIXE as effective and powerful technique providing essential information on metal localisation, repartitioning and major elemental stores in plants on the tissue levels that were not accessible using classical analytical techniques and thus complementing our current understanding of plant metal tolerance mechanisms as a whole.

Pongrac, Paula; Vogel-Mikuš, Katarina; Vavpeti?, Primož; Tratnik, Janja; Regvar, Marjana; Sim?i?, Jurij; Grlj, Nataša; Pelicon, Primož

2010-06-01

17

Nitrate nutrition enhances zinc hyperaccumulation in Noccaea caerulescens (Prayon)  

Microsoft Academic Search

Nitrate fertilization has been shown to increase Zn hyperaccumulation by Noccaea caerulescens (Prayon) (formerly Thlaspi caerulescens). However, it is unknown whether this increased hyperaccumulation is a direct result of NO3\\u000a ? nutrition or due to changes in rhizosphere pH as a result of NO3\\u000a ? uptake. This paper investigated the mechanism of NO3\\u000a ?-enhanced Zn hyperaccumulation in N. caerulescens by

Alison C. Monsant; Yaodong Wang; Caixian Tang

2010-01-01

18

DIFFERENCES IN WHOLE CELL AND SINGLE CHANNEL ION CURRENTS ACROSS THE PLASMA MEMBRANE OF MESOPHYLL CELLS FROM TWO CLOSELY RELATED THLASPI SPECIES  

Technology Transfer Automated Retrieval System (TEKTRAN)

The patch clamp technique was used to study the physiology of ion transport in mesophyll cells from Thlaspi caerulescens, a heavy metal (Zn/Cd) hyperaccumulator species that can tolerate and accumulate very high levels of heavy metals in their leaf cells, and Thlaspi arvense, a related non-accumulat...

19

EXPRESSION PROFILING OF ZN AND OTHER METAL RELATED GENES IN THLASPI CAERULESCENS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Previous research has shown that Thlaspi caerulescens is able to hyperaccumulate as much as 30,000 ppm zinc and 10,000 ppm cadmium in its shoots. In an attempt to better understand the ability of this plant to tolerate and accumulate such high levels of toxic metals, we looked at the expression of g...

20

Functional characterisation of three zinc transporters in Thlaspi caerulescens  

Microsoft Academic Search

Heavy metal hyperaccumulation in plants is a poorly understood phenomenon. Transmembrane metal transporters are assumed to play a key role in this process. In the research described in this thesis, genes encoding Zn transporters of Thlaspicaerulescens<\\/span>, a heavy metal hyperaccumulator plant,<\\/span>are studied and compared to their orthologues in Arabidopsis thaliana, a non-hyperaccumulator plant<\\/span>.<\\/o:p><\\/span>The TcZNT1<\\/span> and Tc

Sangita Talukdar

2007-01-01

21

Soil pH Effects on Uptake of Cd and Zn by Thlaspi caerulescens  

Microsoft Academic Search

For phytoextraction to be successful and viable in environmental remediation, strategies that can optimize plant uptake must\\u000a be identified. Thlaspi caerulescens is an important hyperaccumulator of Cd and Zn, whether adjusting soil pH is an efficient way to enhance metal uptake by T. caerulescens must by clarified. This study used two soils differing in levels of Cd and Zn, which

Autumn S. Wang; J. Scott Angle; Rufus L. Chaney; Thierry A. Delorme; Roger D. Reeves

2006-01-01

22

Molecular dissection of the cellular mechanisms involved in nickel hyperaccumulation in plants. 1998 annual progress report  

SciTech Connect

'Phytoremediation, the use of plants for environmental cleanup of pollutants, including toxic metals, holds the potential to allow the economic restoration of heavy metal and radionuclide contaminated sites. A number of terrestrial plants are known to naturally accumulate high levels of metals in their shoots (1--2% dry weight), and these plants have been termed metal-hyperaccumulators. Clearly, the genetic traits that determine metal-hyperaccumulation offers the potential for the development of practical phytoremediation processes. The long-term objective is to rationally design and generate plants ideally suited for phytoremediation using this unique genetic material. Initially, the strategy will focus on isolating and characterizing the key genetic information needed for expression of the metal-hyperaccumulation phenotype. Recently, histidine has been shown to play a major role in Ni hyperaccumulation. Based on this information the authors propose to investigate, at the molecular level, the role of histidine biosynthesis in Ni hyperaccumulation in Thlaspi goesingense, a Ni hyperaccumulator species.'

Salt, D.

1998-06-01

23

Molecular Dissection of the Cellular Mechanisms Involved in Nickel Hyperaccumulation in Plants  

SciTech Connect

Phytoremediation, the use of plants for environmental cleanup of pollutants, including toxic metals, holds the potential to allow the economic restoration of heavy metal and radionuclide contaminated sites. A number of terrestrial plants are known to naturally accumulate high levels of metals in their shoots (1-2% dry weight), and these plants have been termed metal-hyperaccumulators. Clearly, the genetic traits that determines metal-hyperaccumulation offers the potential for the development of practical phytoremediation processes. Our long-term objective is to rationally design and generate plants ideally suited for phytoremediation using this unique genetic material. Initially, our strategy will focus on isolating and characterizing the key genetic information needed for expression of the metal-hyperaccumulation phenotype. Recently, histidine has been shown to play a major role in Ni hyperaccumulation. Based on this information we propose to investigate, at the molecular level, the role of histidine biosynthesis in Ni hyperaccumulation in Thlaspi goesingense, a Ni hyperaccumulator species. We will clone key genes involved in histidine biosynthesis. We will characterize their transcriptional and post transcriptional regulation by histidine, Ni. We will determine if any of these genes are essential and sufficient for Ni hyperaccumulation by their expression in the non-hyperaccumulator Arabidopsis thaliana.

Salt, David E.

1999-06-01

24

Molecular dissection of the cellular mechanisms involved in nickel hyperaccumulation. 1997 annual progress report  

SciTech Connect

'Phytoremediation, the use of plants for environmental cleanup of pollutants, including toxic metals, holds the potential to allow the economic restoration of heavy metal and radionuclide contaminated sites. A number of terrestrial plants are known to naturally accumulate high levels of metals in their shoots (1--2% dry weight), and these plants have been termed metal-hyperaccumulators. Clearly, the genetic traits that determine metal-hyperaccumulation offers the potential for the development of practical phytoremediation processes. The long-term objective is to rationally design and generate plants ideally suited for phytoremediation using this unique genetic material. Initially, the strategy will focus on isolating and characterizing the key genetic information needed for expression of the metal-hyperaccumulation phenotype. Recently, histidine has been shown to play a major role in Ni hyperaccumulation. Based on this information the authors propose to investigate, at the molecular level, the role of histidine biosynthesis in Ni hyperaccumuIation in Thlaspi goesingense, a Ni hyperaccumulator species.'

Salt, D.E.

1997-10-28

25

Heavy metal uptake and chemical changes in the rhizosphere of Thlaspi caerulescens and Thlaspi ochroleucum grown in contaminated soils  

Microsoft Academic Search

Thlaspi caerulescens (J. and C. Presl) and Thlaspi ochroleucum (Boiss. ex Heldr) were grown in three different soils containing moderate to high amounts of heavy metals in a pot experiment, using a rhizobag technique. T. caerulescens accumulated significantly more Zn in the shoots than T. ochroleucum. The concentrations of Zn in the shoots of T. caerulescens ranged from 3100 to

S. P. McGrath; Z. G. Shen; F. J. Zhao

1997-01-01

26

Phytoextraction potential of the nickel hyperaccumulators Leptoplax emarginata and Bornmuellera tymphaea.  

PubMed

Leptoplax emarginata and Bornmuellera tymphaea are nickel hyperaccumulators of the Brassicaceae family endemic to serpentine soils in Greece. The aims of this work were to compare the growth and uptake behavior of these plants with the Ni hyperaccumulator species Thlaspi caerulescens and Alyssum murale, and to evaluate their effect on soil Ni availability. Plants were grown for 3 mo on three soils that differ in Ni availability. Ni availability in soils was measuredby isotopic exchange kinetics and DTPA-TEA extractions. Results showed that L. emarginata produced significantly more biomass than other plants. On the serpentine soil, B. tymphaea showed the highest Ni concentration in shoots. However, Niphytoextraction on the three soils was maximal with L. emarginata. The high initial Ni availability of soil Serp (470.5 mg kg(-1)) was the main explanation for the high Ni concentrations measured in plant shoots grown on this soil, compared to those grown on soils Calc and Silt A. murale was the least efficient in reducing Ni availability on the serpentine soil L. emarginata appeared as the most efficient species for Ni phytoextraction and decrease of the Ni available pool. PMID:16463544

Chardot, Vanessa; Massoura, Stamatia Tina; Echevarria, Guillaume; Reeves, Roger D; Morel, Jean-Louis

2005-01-01

27

Nickel, Zn and Cd localisation in seeds of metal hyperaccumulators using ?-PIXE spectroscopy  

NASA Astrophysics Data System (ADS)

Metal hyperaccumulators are a rare group of plant species that accumulate exceptionally high concentrations of metals in above ground tissues without showing symptoms of phytotoxicity. Quantitative localisation of the accumulated metals in seed tissues is of considerable interest to help understand the eco-physiology of these unique plant species. We investigated the spatial localisation of metals within seeds of Ni hyperaccumulating Hybanthus floribundus subsp. adpressus, H. floribundus subsp. floribundus and Pimelea leptospermoides and dual-metal (Cd and Zn) hyperaccumulating Thlaspi caerulescens using quantitative micro-proton induced X-ray emission (?-PIXE) spectroscopy. Intact seeds were hand-sectioned, sandwiched between Formvar films and irradiated using the 3 MeV high energy heavy ion microprobe at ANSTO. Elemental maps of whole H. floribundus subsp. adpressus seeds showed an average Ni concentration of 5.1 × 103 mg kg-1 dry weight (DW) with highest Ni concentration in cotyledonary tissues (7.6 × 103 mg kg-1 DW), followed by the embryonic axis (4.4 × 103 mg kg-1 DW). Nickel concentration in whole H. floribundus subsp. floribundus seeds was 3.5 × 102 mg kg-1 DW without a clear pattern of Ni localisation. The average Ni concentration in whole P. leptospermoides seeds was 2.6 × 102 mg kg-1 DW, and Ni was preferentially localised in the embryonic axis (4.3 × 102 mg kg-1 DW). In T. caerulescens, Cd concentrations were similar in cotyledon (4.5 × 103 mg kg-1 DW) and embryonic axis (3.3 × 103 mg kg-1 DW) tissues, whereas Zn was highest in cotyledonary tissues (1.5 × 103 mg kg-1 DW). In all species, the presence of the accumulated metal within the cotyledonary and embryonic axis tissues indicates that the accumulated metal was able to move apoplastically within the seed.

Kachenko, Anthony G.; Bhatia, Naveen P.; Siegele, Rainer; Walsh, Kerry B.; Singh, Balwant

2009-06-01

28

Metal ion ligands in hyperaccumulating plants  

Microsoft Academic Search

Metal-hyperaccumulating plants have the ability to take up extraordinary quantities of certain metal ions without succumbing\\u000a to toxic effects. Most hyperaccumulators select for particular metals but the mechanisms of selection are not understood at\\u000a the molecular level. While there are many metal-binding biomolecules, this review focuses only on ligands that have been reported\\u000a to play a role in sequestering, transporting

Damien L. Callahan; Alan J. M. Baker; Spas D. Kolev; Anthony G. Wedd

2006-01-01

29

Compartmentation and complexation of metals in hyperaccumulator plants  

PubMed Central

Hyperaccumulators are being intensely investigated. They are not only interesting in scientific context due to their “strange” behavior in terms of dealing with high concentrations of metals, but also because of their use in phytoremediation and phytomining, for which understanding the mechanisms of hyperaccumulation is crucial. Hyperaccumulators naturally use metal accumulation as a defense against herbivores and pathogens, and therefore deal with accumulated metals in very specific ways of complexation and compartmentation, different from non-hyperaccumulator plants and also non-hyperaccumulated metals. For example, in contrast to non-hyperaccumulators, in hyperaccumulators even the classical phytochelatin-inducing metal, cadmium, is predominantly not bound by such sulfur ligands, but only by weak oxygen ligands. This applies to all hyperaccumulated metals investigated so far, as well as hyperaccumulation of the metalloid arsenic. Stronger ligands, as they have been shown to complex metals in non-hyperaccumulators, are in hyperaccumulators used for transient binding during transport to the storage sites (e.g., nicotianamine) and possibly for export of Cu in Cd/Zn hyperaccumulators [metallothioneins (MTs)]. This confirmed that enhanced active metal transport, and not metal complexation, is the key mechanism of hyperaccumulation. Hyperaccumulators tolerate the high amount of accumulated heavy metals by sequestering them into vacuoles, usually in large storage cells of the epidermis. This is mediated by strongly elevated expression of specific transport proteins in various tissues from metal uptake in the shoots up to the storage sites in the leaf epidermis. However, this mechanism seems to be very metal specific. Non-hyperaccumulated metals in hyperaccumulators seem to be dealt with like in non-hyperaccumulator plants, i.e., detoxified by binding to strong ligands such as MTs.

Leitenmaier, Barbara; Kupper, Hendrik

2013-01-01

30

The significance of metal hyperaccumulation for biotic interactions  

Microsoft Academic Search

.   Metal hyperaccumulating plants contain very high metal contents. Because of the general toxicity of metals, chemically-mediated\\u000a biotic interactions involving hyperaccumulating plants may differ greatly from those of non-hyperaccumulators. Recent research\\u000a has demonstrated a defensive function for hyperaccumulated metals against herbivores and pathogens. We predict that some herbivore\\/pathogen\\u000a species have evolved metal tolerance, and suggest that resulting high metal levels

Robert S. Boyd; Scott N. Martens

1998-01-01

31

Composition and Physical Properties of Cress (Lepidium sativum L.) and Field Pennycress (Thlaspi arvense L.) Oils  

Technology Transfer Automated Retrieval System (TEKTRAN)

The fatty acid profile and tocopherol, and phytosterol contents of crude cress (Lepidium sativum L.) and field pennycress (Thlaspi arvense L.) oils are reported, along with yields from the corresponding seeds. The physical properties of these oils were also determined, which included oxidative stab...

32

Field Pennycress (Thlaspi arvense L.) Oil: A Promising Source of Biodiesel.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Field pennycress (Thlaspi arvense L., FP) is a winter annual species of the mustard family (Brassicaceae) that is widely distributed throughout temperate North America and which can serve in a winter rotational cycle with conventional crops, thus not displacing existing agricultural production or ne...

33

PHYTOEXTRACTION OF HEAVY METALS WITH HYPERACCUMULATOR PLANTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

When soils contain metals at high enough levels to comprise risk thru food-chain or soil ingestion, some methods must be applied to alleviate the risk, or the land use must be constrained. One approach to remediate risks from some metals is phytoextraction using hyperaccumulator plants. These remark...

34

Organic Acids Accumulation and Antioxidant Enzyme Activities in Thlaspi caerulescens under Zn and Cd Stress  

Microsoft Academic Search

Growth, organic acid and phytochelatin accumulation, as well as the activity of several antioxidative enzymes, i.e. superoxide\\u000a dismutase (SOD), ascorbate peroxidase (APX) guaiacol peroxidase (POX) and catalase (CAT) were investigated under Zn and Cd\\u000a stress in hydroponically growing plants of Thlaspi caerulescens population from Plombires, Belgium. Tissue Zn and Cd concentration increased (the highest concentration of both was in roots)

M. Wójcik; E. Skórzy?ska-Polit; A. Tukiendorf

2006-01-01

35

Arsenic speciation and distribution in an arsenic hyperaccumulating plant  

Microsoft Academic Search

Arsenic-contaminated soil is one of the major arsenic sources for drinking water. Phytoremediation, an emerging, plant-based technology for the removal of toxic contaminants from soil and water, has been receiving renewed attention. Although a number of plants have been identified as hyperaccumulators for the phytoextraction of a variety of metals, and some have been used in field applications, no hyperaccumulator

Weihua Zhang; Yong Cai; Cong Tu; Lena Q Ma

2002-01-01

36

[Determination of sinigrin in semen Thlaspi from Sichuan and Tibet using near infrared diffuse reflectance spectroscopy].  

PubMed

The objective of the present study was to develop a method for the determination of sinigrin in semen Thlaspi from Sichuan using near infrared diffuse reflectance spectroscopy. Near infrared spectra (NIR) in the region of 7,502.1-5,446.2 cm(-1) were recorded for the 246 semen Thlaspi samples containing sinigrin in the content of 1.962%-3.917%. Calibration models were established using the PLS (partial least squares). Different spectra pretreatment methods were compared. The study showed that spectral information can be extracted thoroughly by minimum and maximum normalization pretreatment methods. In this calibration model, the correlation coefficient (R2) was 0.9280, the SEC (standard deviation of the calibration sets) was 0.314 and the SEP (standard deviation of the prediction sets) was 0.388. Results indicated that near infrared diffuse reflectance spectroscopy method can be used to rapidly analyze the valid component in traditional Chinese medicine, and also can be used in the quality control of traditional Chinese medicine. PMID:20038035

Wang, Lei-Lei; Chen, Cong; Zhou, Min; Wang, Jian-Zhong; Luo, Xia; Huang, Guo; Ye, Li-Ming

2009-10-01

37

Isolation and characterization of Arabidopsis halleri and Thlaspi caerulescens phytochelatin synthases  

Microsoft Academic Search

The synthesis of phytochelatins (PC) represents a major metal and metalloid detoxification mechanism in various species. PC\\u000a most likely play a role in the distribution and accumulation of Cd and possibly other metals. However, to date, no studies\\u000a have investigated the phytochelatin synthase (PCS) genes and their expression in the Cd-hyperaccumulating species. We used functional screens in two yeast species

Claire-Lise Meyer; Daniel Peisker; Mikael Courbot; Adrian Radu Craciun; Anne-Claire Cazalé; Denis Desgain; Henk Schat; Stephan Clemens; Nathalie Verbruggen

2011-01-01

38

Arsenic Hyperaccumulation in Gametophytes of Pteris vittata. A New Model System for Analysis of Arsenic Hyperaccumulation1  

PubMed Central

The sporophyte of the fern Pteris vittata is known to hyperaccumulate arsenic (As) in its fronds to >1% of its dry weight. Hyperaccumulation of As by plants has been identified as a valuable trait for the development of a practical phytoremediation processes for removal of this potentially toxic trace element from the environment. However, because the sporophyte of P. vittata is a slow growing perennial plant, with a large genome and no developed genetics tools, it is not ideal for investigations into the basic mechanisms underlying As hyperaccumulation in plants. However, like other homosporous ferns, P. vittata produces and releases abundant haploid spores from the parent sporophyte plant which upon germination develop as free-living, autotrophic haploid gametophyte consisting of a small (<1 mm) single-layered sheet of cells. Its small size, rapid growth rate, ease of culture, and haploid genome make the gametophyte a potentially ideal system for the application of both forward and reverse genetics for the study of As hyperaccumulation. Here we report that gametophytes of P. vittata hyperaccumulate As in a similar manner to that previously observed in the sporophyte. Gametophytes are able to grow normally in medium containing 20 mm arsenate and accumulate >2.5% of their dry weight as As. This contrasts with gametophytes of the related nonaccumulating fern Ceratopteris richardii, which die at even low (0.1 mm) As concentrations. Interestingly, gametophytes of the related As accumulator Pityrogramma calomelanos appear to tolerate and accumulate As to intermediate levels compared to P. vittata and C. richardii. Analysis of gametophyte populations from 40 different P. vittata sporophyte plants collected at different sites in Florida also revealed the existence of natural variability in As tolerance but not accumulation. Such observations should open the door to the application of new and powerful genetic tools for the dissection of the molecular mechanisms involved in As hyperaccumulation in P. vittata using gametophytes as an easily manipulated model system.

Gumaelius, Luke; Lahner, Brett; Salt, David E.; Banks, Jo Ann

2004-01-01

39

Selenium-Tolerant Diamondback Moth Disarms Hyperaccumulator Plant Defense  

Microsoft Academic Search

Summary Background: Some plants hyperaccumulate the toxic element selenium (Se) to extreme levels, up to 1% of dry weight. The function of this intriguing phenomenon is obscure. Results: Here, we show that the Se in the hyperaccumu- lator prince's plume (Stanleya pinnata) protects it from caterpillar herbivory because of deterrence and toxicity. In its natural habitat, however, a newly discovered

John L. Freeman; Colin F. Quinn; Matthew A. Marcus; Sirine Fakra; Elizabeth A. H. Pilon-Smits

2006-01-01

40

Improved Understanding of Hyperaccumulation Yields Commercial Phytoextraction and Phytomining Technologies  

Technology Transfer Automated Retrieval System (TEKTRAN)

This paper reviews progress in phytoextraction of soil elements and illustrates the key role of hyperaccumulator plant species in useful technologies. Much research has focused on elements which are not practically phytoextracted (Pb); on addition of chelating agents which cause unacceptable contam...

41

The Genetic Basis of Metal Hyperaccumulation in Plants  

Microsoft Academic Search

Referee: Professor Alan J.M. Baker, School of Botany, The University of Melbourne, VIC 3010, Australia A relatively small yet diverse group of plants are capable of sequestering metals in their shoot tissues at remarkably high concentrations that would be toxic to most organisms. This process, known as metal hyperaccumulation, is of interest for several reasons, including its relevance to the

A. Joseph Pollard; Keri Dandridge Powell; Frances A. Harper; J. Andrew C. Smith; C. Smith

2002-01-01

42

Plant homeostasis of foliar manganese sinks: specific variation in hyperaccumulators.  

PubMed

Plant manganese (Mn) hyperaccumulation provides unusual insight into homeostasis of this essential micronutrient, in particular its excessive storage in shoot tissues. The compartmentation of hyperaccumulated foliar Mn appears exceptional among metal hyperaccumulators, since it occurs via specific microdistribution patterns. Here, three associated Mn hyperaccumulators, Virotia neurophylla, Maytenus fournieri, and Garcinia amplexicaulis exhibiting distinctly different Mn detoxification strategies were examined. Non-invasive sample preparation in conjunction with cryo scanning electron microscopy (SEM) was used to obtain in vivo quantitative microprobe X-ray and anatomical data from fully hydrated cells. Highly vacuolated large palisade mesophyll cells in V. neurophylla leaves were found to contain around 650 mM Mn. The large non-photosynthetic hypodermal cells of M. fournieri leaves, also with high vacuolar content, and the main site for Mn disposal, had an estimated mean vacuolar Mn concentration of around 600 mM. Previous qualitative X-ray mapping had shown Mn to be almost evenly sequestered across the entire leaf cross section of G. amplexicaulis. However, quantitative data obtained here showed a marked variation in localised concentrations that ranged between ~15 and >800 mM. Notable among these were mean values of >600 mM in spongy mesophyll cells, and ~800 mM within cells of a narrow sub epidermal layer preceding the palisade mesophyll. This study demonstrated the extraordinary Mn carrying capacities of different types of leaf cell vacuoles. PMID:22772585

Fernando, Denise R; Woodrow, Ian E; Baker, Alan J M; Marshall, Alan T

2012-07-07

43

Does hyperaccumulated nickel affect leaf decomposition? A field test using Senecio coronatus (Asteraceae) in South Africa  

Microsoft Academic Search

Summary.  Nickel hyperaccumulator plants contain unusually elevated levels of Ni (>1,000 mg Ni kg?1). The high Ni concentration of hyperaccumulator tissues may affect ecosystem processes such as decomposition, but this has\\u000a yet to be studied under field conditions. We used Senecio coronatus Thunb. (Harv.) from two pairs of serpentine sites: one member of each pair contained a hyperaccumulator population and the\\u000a other

Robert S. Boyd; Micheal A. Davis; Kevin Balkwill

2008-01-01

44

The defense hypothesis of elemental hyperaccumulation: status, challenges and new directions  

Microsoft Academic Search

Elemental hyperaccumulation may have several functions, including plant defense against natural enemies. A total of 34 studies,\\u000a including 72 experimental tests, have been conducted to date. At least some tests have demonstrated defense by hyperaccumulated\\u000a As, Cd, Ni, Se and Zn, but relatively few plant taxa and natural enemies have been investigated. Defense by hyperaccumulated\\u000a Ni has been shown for

Robert S. Boyd

2007-01-01

45

Examining the ecological paradox of the ‘mycorrhizal-metal-hyperaccumulators  

Microsoft Academic Search

This analysis identifies and attempts to resolve the paradox of combining plant hyperaccumulators and arbuscular mycorrhizal fungi (AMF) for the purpose of post-industrial bioremediation due to the divergence of their respective ecological and evolutionary stress-tolerance behaviors. The identification of a ‘dilemma of resource allocation’ associated with plant resources consumed in intrinsic (e.g. metabolic) vs. extrinsic (e.g. symbiotic) stress-tolerance mechanisms could

Patrick Audet

2012-01-01

46

EFFECTS OF THE NICKEL HYPERACCUMULATOR ALYSSUM MURALE ON RHIZOSHERE MICROBIAL POPULATIONS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Metal hyperaccumulator plants like Alyssum murale are used for phytoremediation of Ni contaminated soils. Soil microorganisms are known to play an important role in nutrient acquisition for plants, however, little is known about the rhizosphere microorganisms of hyperaccumulators. Fresh and dry weig...

47

Nickel defends the South African hyperaccumulator Senecio coronatus (Asteraceae) against Helix aspersa (Mollusca: Pulmonidae)  

Microsoft Academic Search

Summary. The elevated Ni concentration of Ni hyper- accumulator plants has been proposed to be an effec- tive chemical defence against herbivores. To test this hypothesis, we fed leaves from hyperaccumulator and non-hyperaccumulator populations of South African Senecio coronatus to a generalist herbivore species, the brown garden snail (Helix aspersa). Snails fed hyperac- cumulator leaves experienced significantly greater mor- tality

Robert S. Boyd; Micheal A. Davis; Michael A. Wall; Kevin Balkwill

2002-01-01

48

Constitutively High Expression of the Histidine Biosynthetic Pathway Contributes to Nickel Tolerance in Hyperaccumulator Plants  

Microsoft Academic Search

Plants that hyperaccumulate Ni exhibit an exceptional degree of Ni tolerance and the ability to translocate Ni in large amounts from root to shoot. In hyperaccumulator plants in the genus Alyssum, free His is an important Ni binding ligand that increases in the xylem proportionately to root Ni uptake. To determine the molecular basis of the His response and its

Robert A. Ingle; Sam T. Mugford; Jonathan D. Rees; Malcolm M. Campbell; J. Andrew; C. Smith

2005-01-01

49

A thiocyanate-forming protein generates multiple products upon allylglucosinolate breakdown in Thlaspi arvense.  

PubMed

Glucosinolates, amino acid-derived thioglycosides found in plants of the Brassicales order, are one of the best studied classes of plant secondary metabolites. Together with myrosinases and supplementary proteins known as specifier proteins, they form the glucosinolate-myrosinase system that upon tissue damage gives rise to a number of biologically active glucosinolate breakdown products such as isothiocyanates, epithionitriles and organic thiocyanates involved in plant defense. While isothiocyanates are products of the spontaneous rearrangement of the glucosinolate aglycones released by myrosinase, the formation of epithionitriles and organic thiocyanates depends on both myrosinases and specifier proteins. Hydrolysis product profiles of many glucosinolate-containing plant species indicate the presence of specifier proteins, but only few have been identified and characterized biochemically. Here, we report on cDNA cloning, heterologous expression and characterization of TaTFP, a thiocyanate-forming protein (TFP) from Thlaspi arvense L. (Brassicaceae), that is expressed in all plant organs and can be purified in active form after heterologous expression in Escherichia coli. As a special feature, this protein promotes the formation of allylthiocyanate as well as the corresponding epithionitrile upon myrosinase-catalyzed hydrolysis of allylglucosinolate, the major glucosinolate of T. arvense. All other glucosinolates tested are converted to their simple nitriles when hydrolyzed in the presence of TaTFP. Despite its ability to promote allylthiocyanate formation, TaTFP has a higher amino acid sequence similarity to known epithiospecifier proteins (ESPs) than to Lepidium sativum TFP. However, unlike Arabidopsis thaliana ESP, its activity in vitro is not strictly dependent on Fe²? addition to the assay mixtures. The availability of TaTFP in purified form enables future studies to be aimed at elucidating the structural bases of specifier protein specificities and mechanisms. Furthermore, identification of TaTFP shows that product specificities of specifier proteins can not be predicted based on amino acid sequence similarity and raises interesting questions about specifier protein evolution. PMID:21783213

Kuchernig, Jennifer-C; Backenköhler, Anita; Lübbecke, Maike; Burow, Meike; Wittstock, Ute

2011-07-21

50

Selection and Characterization of a Gibberellin-Deficient Mutant of Thlaspi arvense L. 1  

PubMed Central

Field pennycress (Thlaspi arvense L.) is a winter annual weed with a cold requirement for reproductive development. Previous work in this laboratory has demonstrated that the bolting aspect (rapid stem growth) of reproductive development is mediated by gibberellins (GA). The present paper describes the selection and characterization of a mutant lacking the capacity for thermoinduced stem growth. Seeds of an inbred field pennycress line (CR1) were treated with the chemical mutagen ethyl methane sulfonate, germinated, and allowed to produce seed. Plants derived from these seeds were screened for reduced stem growth. A mutant line, EMS-141, in which the lack of stem growth can be fully overcome with exogenous GA3, was selected for further analysis. Other phenotypic abnormalities exhibited by the mutant line include reduced petiole growth, slightly delayed floral initiation, and failure of flowers to develop fully. These are also reversed with exogenous GA3. Evidence is presented indicating that all of the alterations in growth and development exhibited by EMS-141 are conferred by a recessive mutation of a single nuclear gene. Through quantitative analysis of endogenous GA and GA precursors and a comparison of the abilities of various compounds to restore normal growth when applied to plants of EMS-141, the physiological basis for the mutant phenotype was determined to be the result of highly reduced endogenous GA levels. Moreover, the affected site in GA biosynthesis appears to be the accumulation of ent-kaurene, probably at the level of ent-kaurene synthase. The relative abilities of exogenous GA and GA precursors to restore normal growth of petioles and stems are compared, and the results are used to make inferences on the functions of the two different pathways of GA metabolism that exist in field pennycress. Images Figure 2

Metzger, James D.; Hassebrock, Amy T.

1990-01-01

51

Genetic and Molecular Dissection of Arsenic Hyperaccumulation in the fern Pteris vittata.  

SciTech Connect

Pteris vittata is a fern that is extraordinary in its ability to tolerate hyperaccumulate high levels of arsenic (As). The goals of the proposed research, to identify the genes that are necessary for As hyperaccumulation in P. vittata using molecular and genetic approaches and to understand the physiology of arsenic uptake and distribution in the living plant, were accomplished during the funding period. The genes that have been identified may ultimately enable the engineering or selection of other plants capable of As hyperaccumulation. This is important for the phytoremediation of arsenic-contaminated soils in areas where P. vittata cannot grow.

Jo Ann Banks; David Salt

2008-04-04

52

Nopalea cochenillifera, a potential chromium (VI) hyperaccumulator plant.  

PubMed

Hexavalant chromium [Cr(VI)] tolerance and accumulation in in vitro grown Nopalea cochenillifera Salm. Dyck. plants was investigated. A micropropagation protocol was establish for a rapid multiplication of N. cochenillifera and [Cr(VI)] tolerance and accumulation was studied in in vitro grown cultures. Cr concentration was estimated by atomic absorption spectroscopy in roots and shoots to confirm plant's hyperaccumulation capacity. Plants showed tolerance up to 100 ?M K(2)Cr(2)O(7) without any significant changes in root growth after 16 days treatment; whereas, chlorophyll content in plants treated with 1 and 10 ?M K(2)Cr(2)O(7) were not so different than the control plant. The levels of lipid peroxidation and protein oxidation increased significantly (p < 0.01) with increasing concentration of chromium. Exposures of N. cochenillifera to lower concentrations of K(2)Cr(2)O(7) (? 10 ?M) induced catalase (CAT) and superoxide dismutase (SOD) significantly (p < 0.001) but higher concentrations of K(2)Cr(2)O(7) (>100 ?M) inhibited the activities of CAT and SOD. Roots accumulated a maximum of 25,263.396 ± 1,722.672 mg Cr Kg(-1) dry weight (DW); while the highest concentration of Cr in N. cochenillifera shoots was 705.714 ± 32.324 mg Cr Kg(-1) DW. N. cochenillifera could be a prospective hyperaccumulator plant of Cr(VI) and a promising candidate for phytoremediation purposes. PMID:22914913

Adki, Vinayak S; Jadhav, Jyoti P; Bapat, Vishwas A

2012-08-23

53

Molecular Dissection of The Cellular Mechanisms Involved In Nickel Hyperaccumulation in Plants  

SciTech Connect

Hyperaccumulator plant species are able to accumulate between 1-5% of their biomass as metal. However, these plants are often small, slow growing, and do not produce a high biomass. Phytoextraction, a cost-effective, in situ, plant based approach to soil remediation takes advantage of the remarkable ability of hyperaccumulating plants to concentrate metals from the soil and accumulate them in their harvestable, above-ground tissues. However, to make use of the valuable genetic resources identified in metal hyperaccumulating species, it will be necessary to transfer this material to high biomass rapidly growing crop plants. These plants would then be ideally suited to the phytoremediation process, having the ability to produce large amount of metal-rich plant biomass for rapid harvest and soil cleanup. Although progress is being made in understanding the genetic basis of metal hyperaccumulation a more complete understanding will be necessary before we can take full advantage of the genetic potential of these plants.

David E. Salt

2002-04-08

54

Microbeam methodologies as powerful tools in manganese hyperaccumulation research: present status and future directions.  

PubMed

Microbeam studies over the past decade have garnered unique insight into manganese (Mn) homeostasis in plant species that hyperaccumulate this essential mineral micronutrient. Electron- and/or proton-probe methodologies employed to examine tissue elemental distributions have proven highly effective in illuminating excess foliar Mn disposal strategies, some apparently unique to Mn hyperaccumulating plants. When applied to samples prepared with minimal artefacts, these are powerful tools for extracting true 'snapshot' data of living systems. For a range of reasons, Mn hyperaccumulation is particularly suited to in vivo interrogation by this approach. Whilst microbeam investigation of metallophytes is well documented, certain methods originally intended for non-biological samples are now widely applied in biology. This review examines current knowledge about Mn hyperaccumulators with reference to microbeam methodologies, and discusses implications for future research into metal transporters. PMID:23970891

Fernando, Denise R; Marshall, Alan; Baker, Alan J M; Mizuno, Takafumi

2013-08-20

55

Differences in Whole-Cell and Single-Channel Ion Currents across the Plasma Membrane of Mesophyll Cells from Two Closely Related Thlaspi Species  

PubMed Central

The patch clamp technique was used to study the physiology of ion transport in mesophyll cells from two Thlaspi spp. that differ significantly in their physiology. In comparison with Thlaspi arvense, Thlaspi caerulescens (a heavy metal accumulator) can grow in, tolerate, and accumulate very high levels of certain heavy metals (primarily zinc [Zn] and cadmium) in their leaf cells. The membrane conductance of every T. arvense leaf cell was dominated by a slowly activating, time-dependent outward rectifying current (SKOR). In contrast, only 23% of T. caerulescens cells showed SKOR activity, whereas the remaining 77% exhibit a rapidly developing instantaneous K+ outward rectifier (RKOR) current. In contrast to RKOR, the channels underlying the SKOR current were sensitive to changes in the extracellular ion activity. Single-channel recordings indicated the existence of K+ channel populations with similar unitary conductances, but distinct channel kinetics and regulation. The correlation between these recordings and the whole-cell data indicated that although one type of channel kinetics is preferentially activated in each Thlaspi spp., both species have the capability to switch between either type of current. Ion substitution in whole-cell and single-channel experiments indicated that although the SKOR and RKOR channels mediate a net outward K+ current, they can also allow a significant Zn2+ permeation (i.e. influx). In addition, single-channel recordings allowed us to identify an infrequent type of plasma membrane divalent cation channel that also can mediate Zn2+ influx. We propose that the different K+ channel types or channel states may result from and are likely to reflect differences in the cytoplasmic and apoplastic ionic environment in each species. Thus, the ability to interchangeably switch between different channel states allows each species to constantly adjust to changes in their apoplastic ionic environment.

Pineros, Miguel A.; Kochian, Leon V.

2003-01-01

56

Phytoextraction of cadmium and physiological changes in Solanum nigrum as a novel cadmium hyperaccumulator  

Microsoft Academic Search

It is still difficult to fully understand the physiological, biochemical, and molecular mechanisms involved in metal hyperaccumulation\\u000a and how plants adjust to an adverse environment. Solanum nigrum L. is a novel Cd-hyperaccumulator, which antioxidant defense and photosynthetic CO2 fixation were investigated in this study. The results showed that the elevated heavy metal concentration, inhibiting S. nigrum growth, was accompanied by

Y. Gao; P. Zhou; L. Mao; W. J. Shi; Y. E. Zhi

2010-01-01

57

Fertilizer amendment for improving the phytoextraction of cadmium by a hyperaccumulator Rorippa globosa (Turcz.) Thell  

Microsoft Academic Search

Purpose  Two main pathways of phytoremediation of heavy metal-contaminated soils are phytostabilization and phytoextraction. Some soil\\u000a amendments can strengthen phytostabilization or phytoextraction through either reducing heavy metal bioavailability in soil\\u000a or increasing the heavy metal accumulation capacity of the hyperaccumulator (enhancing heavy metal concentration or shoot\\u000a biomass of the hyperaccumulator). Urea and chicken manure are often used as fertilizers. This research

Shuhe Wei; Jiangong Zhu; Qixing X. Zhou; Jie Zhan

58

Elemental and metabolite profiling of nickel hyperaccumulators from New Caledonia.  

PubMed

Leaf material from nine Ni hyperaccumulating species was collected in New Caledonia: Homalium kanaliense (Vieill.) Briq., Casearia silvana Schltr, Geissois hirsuta Brongn. & Gris, Hybanthus austrocaledonicus Seem, Psychotria douarrei (G. Beauvis.) Däniker, Pycnandra acuminata (Pierre ex Baill.) Swenson & Munzinger (syn Sebertia acuminata Pierre ex Baill.), Geissois pruinosa Brongn. & Gris, Homalium deplanchei (Viell) Warb. and Geissois bradfordii (H.C. Hopkins). The elemental concentration was determined by inductively-coupled plasma optical emission spectrometry (ICP-OES) and from these results it was found that the species contained Ni concentrations from to 250-28,000 mg/kg dry mass. Gas chromatography mass spectrometry (GC-MS)-based metabolite profiling was then used to analyse leaves of each species. The aim of this study was to target Ni-binding ligands through correlation analysis of the metabolite levels and leaf Ni concentration. Approximately 258 compounds were detected in each sample. As has been observed before, a correlation was found between the citric acid and Ni concentrations in the leaves for all species collected. However, the strongest Ni accumulator, P. douarrei, has been found to contain particularly high concentrations of malonic acid, suggesting an additional storage mechanism for Ni. A size exclusion chromatography separation protocol for the separation of Ni-complexes in P. acuminata sap was also applied to aqueous leaf extracts of each species. A number of metabolites were identified in complexes with Ni including Ni-malonate from P. douarrei. Furthermore, the levels for some metabolites were found to correlate with the leaf Ni concentration. These data show that Ni ions can be bound by a range of small molecules in Ni hyperaccumulation in plants. PMID:22795763

Callahan, Damien L; Roessner, Ute; Dumontet, Vincent; De Livera, Alysha M; Doronila, Augustine; Baker, Alan J M; Kolev, Spas D

2012-07-12

59

THE EFFECT OF THE PH OF PH BUFFERED NUTRIENT SOLUTIONS ON NICKEL HYPERACCUMULATION BY ALYSSUM CORSICUM AND BERKHEYA CODDII  

Technology Transfer Automated Retrieval System (TEKTRAN)

It is hypothesized that plant hyperaccumulation of Ni evolved as a defense mechanism against diseases and insects. Two hyperaccumulators, Alyssum corsicum and Berkheya coddii, were compared to cabbage (Brassica oleracea) grown in MES-HEPES buffered nutrient solutions and maintained at four pH levels...

60

Arsenic hyperaccumulation by Pteris vittata from arsenic contaminated soils and the effect of liming and phosphate fertilisation  

Microsoft Academic Search

Pot experiments were carried out to investigate the potential of phytoremediation with the arsenic hyperaccumulator Pteris vittata in a range of soils contaminated with As and other heavy metals, and the influence of phosphate and lime additions on As hyperaccumulation by P. vittata. The fern was grown in 5 soils collected from Cornwall (England) containing 67–4550 mg As kg?1 and

N Caille; S Swanwick; F. J Zhao; S. P McGrath

2004-01-01

61

Elucidating the selenium and arsenic metabolic pathways following exposure to the non-hyperaccumulating Chlorophytum comosum, spider plant  

Microsoft Academic Search

Although many studies have investigated the metabolism of selenium and arsenic in hyperaccumulating plants for phytoremediation purposes, few have explored non-hyperaccumulating plants as a model for general contaminant exposure to plants. In addition, the result of simultaneous supplementation with selenium and arsenic has not been investigated in plants. In this study, Chlorophytum comosum, commonly known as the spider plant, was

Scott E. Afton; Brittany Catron; Joseph A. Caruso

2009-01-01

62

Transient Influx of nickel in root mitochondria modulates organic acid and reactive oxygen species production in nickel hyperaccumulator Alyssum murale.  

PubMed

Mitochondria are important targets of metal toxicity and are also vital for maintaining metal homeostasis. Here, we examined the potential role of mitochondria in homeostasis of nickel in the roots of nickel hyperaccumulator plant Alyssum murale. We evaluated the biochemical basis of nickel tolerance by comparing the role of mitochondria in closely related nickel hyperaccumulator A. murale and non-accumulator Alyssum montanum. Evidence is presented for the rapid and transient influx of nickel in root mitochondria of nickel hyperaccumulator A. murale. In an early response to nickel treatment, substantial nickel influx was observed in mitochondria prior to sequestration in vacuoles in the roots of hyperaccumulator A. murale compared with non-accumulator A. montanum. In addition, the mitochondrial Krebs cycle was modulated to increase synthesis of malic acid and citric acid involvement in nickel hyperaccumulation. Furthermore, malic acid, which is reported to form a complex with nickel in hyperaccumulators, was also found to reduce the reactive oxygen species generation induced by nickel. We propose that the interaction of nickel with mitochondria is imperative in the early steps of nickel uptake in nickel hyperaccumulator plants. Initial uptake of nickel in roots results in biochemical responses in the root mitochondria indicating its vital role in homeostasis of nickel ions in hyperaccumulation. PMID:23322782

Agrawal, Bhavana; Czymmek, Kirk J; Sparks, Donald L; Bais, Harsh P

2013-01-15

63

First evidence on different transportation modes of arsenic and phosphorus in arsenic hyperaccumulator Pteris vittata.  

PubMed

Arsenic (As) reduction and translocation are key processes for As hyperaccumulation by the hyperaccumulator Pteris vittata L. Micro-X-ray adsorption spectroscopy of P. vittata's rhizoid tissues revealed that As reduction mainly occurred in endodermis during translocation from epidermis to vascular bundle. Prior to reduction, arsenate (As (V)) translocation was an active process requiring energy and employing a phosphate (P) transporter. Use of a synchrotron X-ray microprobe showed that As (V) and P were cotransported and that this process could be enhanced by As (V) exposure or P deficiency but restrained by energy release inhibition caused by 2,4-dinitrophenol or sodium orthovanadate. In contrast, after As reduction, As(III) translocation differed from P translocation and was more efficient, appearing free from the apparent endodermal blockage. The results here revealed the role of the P transporter on As translocation as well as the key role of As reduction in As hyperaccumulation by P. vittata. PMID:22230060

Lei, Mei; Wan, Xiao-Ming; Huang, Ze-Chun; Chen, Tong-Bin; Li, Xue-Wen; Liu, Ying-Ru

2011-10-21

64

Selenium Distribution and Speciation in the Hyperaccumulator Astragalus bisulcatus and Associated Ecological Partners1[W][OA  

PubMed Central

The goal of this study was to investigate how plant selenium (Se) hyperaccumulation may affect ecological interactions and whether associated partners may affect Se hyperaccumulation. The Se hyperaccumulator Astragalus bisulcatus was collected in its natural seleniferous habitat, and x-ray fluorescence mapping and x-ray absorption near-edge structure spectroscopy were used to characterize Se distribution and speciation in all organs as well as in encountered microbial symbionts and herbivores. Se was present at high levels (704–4,661 mg kg?1 dry weight) in all organs, mainly as organic C-Se-C compounds (i.e. Se bonded to two carbon atoms, e.g. methylselenocysteine). In nodule, root, and stem, up to 34% of Se was found as elemental Se, which was potentially due to microbial activity. In addition to a nitrogen-fixing symbiont, the plants harbored an endophytic fungus that produced elemental Se. Furthermore, two Se-resistant herbivorous moths were discovered on A. bisulcatus, one of which was parasitized by a wasp. Adult moths, larvae, and wasps all accumulated predominantly C-Se-C compounds. In conclusion, hyperaccumulators live in association with a variety of Se-resistant ecological partners. Among these partners, microbial endosymbionts may affect Se speciation in hyperaccumulators. Hyperaccumulators have been shown earlier to negatively affect Se-sensitive ecological partners while apparently offering a niche for Se-resistant partners. Through their positive and negative effects on different ecological partners, hyperaccumulators may influence species composition and Se cycling in seleniferous ecosystems.

Valdez Barillas, Jose R.; Quinn, Colin F.; Freeman, John L.; Lindblom, Stormy D.; Fakra, Sirine C.; Marcus, Matthew A.; Gilligan, Todd M.; Alford, Elan R.; Wangeline, Ami L.; Pilon-Smits, Elizabeth A.H.

2012-01-01

65

Forms of Zinc Accumulated in the Hyperaccumulator Arabidopsis halleri1  

PubMed Central

The chemical forms of zinc (Zn) in the Zn-tolerant and hyperaccumulator Arabidopsis halleri and in the non-tolerant and nonaccumulator Arabidopsis lyrata subsp. petraea were determined at the molecular level by combining chemical analyses, extended x-ray absorption spectroscopy (EXAFS), synchrotron-based x-ray microfluorescence, and ?EXAFS. Plants were grown in hydroponics with various Zn concentrations, and A. halleri specimens growing naturally in a contaminated site were also collected. Zn speciation in A. halleri was independent of the origin of the plants (contaminated or non-contaminated) and Zn exposure. In aerial parts, Zn was predominantly octahedrally coordinated and complexed to malate. A secondary organic species was identified in the bases of the trichomes, which contained elevated Zn concentrations, and in which Zn was tetrahedrally coordinated and complexed to carboxyl and/or hydroxyl functional groups. This species was detected thanks to the good resolution and sensitivity of synchrotron-based x-ray microfluorescence and ?EXAFS. In the roots of A. halleri grown in hydroponics, Zn phosphate was the only species detected, and is believed to result from chemical precipitation on the root surface. In the roots of A. halleri grown on the contaminated soil, Zn was distributed in Zn malate, Zn citrate, and Zn phosphate. Zn phosphate was present in both the roots and aerial part of A. lyrata subsp. petraea. This study illustrates the complementarity of bulk and spatially resolved techniques, allowing the identification of: (a) the predominant chemical forms of the metal, and (b) the minor forms present in particular cells, both types of information being essential for a better understanding of the bioaccumulation processes.

Sarret, Geraldine; Saumitou-Laprade, Pierre; Bert, Valerie; Proux, Olivier; Hazemann, Jean-Louis; Traverse, Agnes; Marcus, Matthew A.; Manceau, Alain

2002-01-01

66

Rhizosphere Microbial Densities and Trace Metal Tolerance of the Nickel Hyperaccumulator Alyssum Serpyllifolium Subsp. Lusitanicum  

Microsoft Academic Search

In this study we determine culturable microbial densities (total heterotrophs, ammonifiers, amylolytics and cellulolytics) and bacterial resistance to Co, Cr, and Ni in bulk and rhizosphere soils of three populations of the Ni-hyperaccumulator Alyssum serpyllifolium subsp. lusitanicum and the excluder Dactylis glomerata from ultramafic sites (two populations in Northeast (NE) Portugal (Samil (S), Morais (M)) and one population in Northwest

C. Becerra-Castro; C. Monterroso; M. García-Lestón; A. Prieto-Fernández; M. J. Acea; P. S. Kidd

2009-01-01

67

The potential of the high-biomass nickel hyperaccumulator Berkheya coddii for phytoremediation and phytomining  

Microsoft Academic Search

Pot trials and tests in outside plots were carried out on the South African Ni hyperaccumulator plant Berkheya coddii in order to establish its potential for phytoremediation of contaminated soils and for phytomining of Ni. Outside trial plots showed that a dry biomass of 22 t\\/ha could be achieved after moderate fertilisation. Pot trials with varying soil amendments with nitrogen

B. H. Robinson; R. R. Brooks; A. W. Howes; J. H. Kirkman; P. E. H. Gregg

1997-01-01

68

SIMULTANEOUS HYPERACCUMULATION OF NICKEL, MANGANESE AND CALCIUM IN ALYSSUM LEAF TRICHOMES  

Technology Transfer Automated Retrieval System (TEKTRAN)

We have developed commercially viable phytoremediation/phytomining technologies employing Alyssum Ni-hyperaccumulator species to quantitatively extract Ni from soils. Nickel is mainly stored in Alyssum leaf epidermal cells. The leaf epidermis is covered with an overlapping network of stellate tric...

69

Role of Hyperaccumulators in Phytoextraction of Metals From Contaminated Mining Sites: A Review  

Microsoft Academic Search

Accumulation of heavy metals in selective locations of the environment has been attracting considerable public attention over the last decades. The conventional clean-up technologies to extract and remove heavy metals from mining sites are either inadequate or too expensive for developing countries. In the past decades, research efforts have been directed toward phytoextraction by using hyperaccumulators as an alternative, low-cost

V. Sheoran; A. S. Sheoran; P. Poonia

2010-01-01

70

Antioxidant responses of hyper-accumulator and sensitive fern species to arsenic  

Microsoft Academic Search

Plant species capable of hyper-accumulating heavy metals are of considerable interest for phytoremedia- tion, and differ in their ability to accumulate metals from the environment. This work aims to examine (i) arsenic accumulation in three fern species (Chinese brake fern (Pteris vittata L.), slender brake fern (Pteris ensiformis Burm. f.), and Boston fern (Nephrolepis exaltata L.)), which were exposed to

Mrittunjai Srivastava; Lena Q. Ma; Nandita Singh; Shraddha Singh

2005-01-01

71

Nickel hyperaccumulation as an elemental defense of Streptanthus polygaloides (Brassicaceae): influence of herbivore feeding mode.  

PubMed

No study of a single nickel (Ni) hyperaccumulator species has investigated the impact of hyperaccumulation on herbivores representing a variety of feeding modes. Streptanthus polygaloides plants were grown on high- or low-Ni soils and a series of no-choice and choice feeding experiments was conducted using eight arthropod herbivores. Herbivores used were two leaf-chewing folivores (the grasshopper Melanoplus femurrubrum and the lepidopteran Evergestis rimosalis), a dipteran rhizovore (the cabbage maggot Delia radicum), a xylem-feeder (the spittlebug Philaenus spumarius), two phloem-feeders (the aphid, Lipaphis erysimi and the spidermite Trialeurodes vaporariorum) and two cell-disruptors (the bug Lygus lineolaris and the whitefly Tetranychus urticae). Hyperaccumulated Ni significantly decreased survival of the leaf-chewers and rhizovore, and significantly reduced population growth of the whitefly cell-disruptor. However, vascular tissue-feeding insects were unaffected by hyperaccumulated Ni, as was the bug cell-disruptor. We conclude that Ni can defend against tissue-chewing herbivores but is ineffective against vascular tissue-feeding herbivores. The effects of Ni on cell-disruptors varies, as a result of either variation of insect Ni sensitivity or the location of Ni in S. polygaloides cells and tissues. PMID:16219073

Jhee, Edward M; Boyd, Robert S; Eubanks, Micky D

2005-11-01

72

The metal hyperaccumulators from New Caledonia can broaden our understanding of nickel accumulation in plants  

PubMed Central

While an excess of metals such as zinc, cadmium or nickel (Ni) is toxic for most plants, about 500 plant species called hyperaccumulators are able to accumulate high amounts of these metals. These plants and the underlying mechanisms are receiving an increasing interest because of their potential use in sustainable biotechnologies such as biofortification, phytoremediation, and phytomining. Among hyperaccumulators, about 400 species scattered in 40 families accumulate Ni. Despite this wide diversity, our current knowledge of the mechanisms involved in Ni accumulation is still limited and mostly restricted to temperate herbaceous Brassicaceae. New Caledonia is an archipelago of the tropical southwest pacific with a third of its surface (5500 km2) covered by Ni-rich soils originating from ultramafic rocks. The rich New Caledonia flora contains 2145 species adapted to these soils, among which 65 are Ni hyperaccumulators, including lianas, shrubs or trees, mostly belonging to the orders Celastrales, Oxalidales, Malpighiales, and Gentianales. We present here our current knowledge on Ni hyperaccumulators from New Caledonia and the latest molecular studies developed to better understand the mechanisms of Ni accumulation in these plants.

Jaffre, Tanguy; Pillon, Yohan; Thomine, Sebastien; Merlot, Sylvain

2013-01-01

73

SPECTROMICROSCOPIC INVESTIGATION OF CO SPECIATION IN A NI/CO HYPERACCUMULATOR PLANT USED FOR PHYTOREMEDIATION AND PHYTOMINING  

Technology Transfer Automated Retrieval System (TEKTRAN)

Metal contamination of surface and subsurface environments is a worldwide concern. Unique metallophyte plants (hyperaccumulators) accumulate high concentrations of trace metals in their harvestable biomass, and thereby offer a sustainable method for treatment of metal-contaminated sites (phytoremed...

74

Plant-by-Plant Variations of Bacterial Communities Associated with Leaves of the Nickel Hyperaccumulator Alyssum bertolonii Desv  

Microsoft Academic Search

Bacteria associated with tissues of metal-hyperaccumulating plants are of great interest due to the multiple roles they may\\u000a play with respect to plant growth and resistance to heavy metals. The variability of bacterial communities associated with\\u000a plant tissues of three populations of Alyssum bertolonii, a Ni hyperaccumulator endemic of serpentine outcrops of Central Italy, was investigated. Terminal-restriction fragment length\\u000a polymorphism

Alessio Mengoni; Francesco Pini; Li-Nan Huang; Wen-Sheng Shu; Marco Bazzicalupo

2009-01-01

75

The role of selenium in protecting plants against prairie dog herbivory: implications for the evolution of selenium hyperaccumulation  

Microsoft Academic Search

Some plants can hyperaccumulate the element selenium (Se) up to 10,000 mg Se kg?1 dry weight. Hyperaccumulation has been hypothesized to defend against herbivory. In laboratory studies high Se levels protect\\u000a plants from invertebrate herbivores and pathogens. However, field studies and mammalian herbivore studies that link Se accumulation\\u000a to herbivory protection are lacking. In this study a combination of field surveys

Colin F. Quinn; John L. Freeman; Miriam L. Galeas; Erin M. Klamper; Elizabeth A. H. Pilon-Smits

2008-01-01

76

Interactions of selenium hyperaccumulators and nonaccumulators during cocultivation on seleniferous or nonseleniferous soil--the importance of having good neighbors.  

PubMed

• This study investigated how selenium (Se) affects relationships between Se hyperaccumulator and nonaccumulator species, particularly how plants influence their neighbors' Se accumulation and growth. • Hyperaccumulators Astragalus bisulcatus and Stanleya pinnata and nonaccumulators Astragalus?drummondii and Stanleya?elata were cocultivated on seleniferous or nonseleniferous soil, or on gravel supplied with different selenate concentrations. The plants were analyzed for growth, Se accumulation and Se speciation. Also, root exudates were analyzed for Se concentration. • The hyperaccumulators showed 2.5-fold better growth on seleniferous than on nonseleniferous soil, and up to fourfold better growth with increasing Se supply; the nonaccumulators showed the opposite results. Both hyperaccumulators and nonaccumulators could affect growth (up to threefold) and Se accumulation (up to sixfold) of neighboring plants. Nonaccumulators S. elata and A. drummondii accumulated predominantly (88-95%) organic C-Se-C; the remainder was selenate. S. elata accumulated relatively more C-Se-C and less selenate when growing adjacent to S. pinnata. Both hyperaccumulators released selenocompounds from their roots. A. bisulcatus exudate contained predominantly C-Se-C compounds; no speciation data could be obtained for S. pinnata. • Thus, plants can affect Se accumulation in neighbors, and soil Se affects competition and facilitation between plants. This helps to explain why hyperaccumulators are found predominantly on seleniferous soils. PMID:22269105

Mehdawi, Ali F El; Cappa, Jennifer J; Fakra, Sirine C; Self, James; Pilon-Smits, Elizabeth A H

2012-01-23

77

Developing an Agrobacterium tumefaciens -mediated genetic transformation for a selenium-hyperaccumulator Astragalus racemosus  

Microsoft Academic Search

Agrobacterium\\u000a tumefaciens strain LBA4404 containing the plasmid pBI121, carrying the reporter gene uidA and the kanamycin resistance gene nptII, was used for gene transfer experiments in selenium (Se)-hyperaccumulator Astragalus racemosus. The effects of kanamycin on cell growth and division and acetosyringone on transformation efficiency were evaluated. The\\u000a optimal concentration of kanamycin that could effectively inhibit cell growth and division in

Diane E. Darlington; Chiu-Yueh Hung; Jiahua Xie

2009-01-01

78

Responses to Nickel in the Proteome of the Hyperaccumulator Plant Alyssum lesbiacum  

Microsoft Academic Search

A proteomic analysis of the Ni hyperaccumulator plant Alyssum lesbiacum was carried out to identify proteins that may play a role in the exceptional degree of Ni tolerance and accumulation characteristic\\u000a of this metallophyte. Of the 816 polypeptides detected in root tissue by 2D SDS-PAGE, eleven increased and one decreased in\\u000a abundance relative to total protein after 6-week-old plants were

Robert A. Ingle; J. Andrew C. Smith; Lee J. Sweetlove

2005-01-01

79

Isolation and Characterization of Endophytic Bacteria from the Nickel Hyperaccumulator Plant Alyssum bertolonii  

Microsoft Academic Search

We report the isolation and characterization of endophytic bacteria, endemic to serpentine outcrops of Central Italy, from\\u000a a nickel hyperaccumulator plant, Alyssum bertolonii Desv. (Brassicaceae). Eighty-three endophytic bacteria were isolated from roots, stems, and leaves of A. bertolonii and classified by restriction analysis of 16S rDNA (ARDRA) and partial 16S rDNA sequencing in 23 different taxonomic groups.\\u000a All isolates were

Rita Barzanti; Francesca Ozino; Marco Bazzicalupo; Roberto Gabbrielli; Francesca Galardi; Cristina Gonnelli; Alessio Mengoni

2007-01-01

80

Cellular compartmentation of cadmium and zinc in relation to other elements in the hyperaccumulator Arabidopsis halleri  

Microsoft Academic Search

.   The cellular compartmentation of elements was analysed in the Zn hyperaccumulator Arabidopsis halleri (L.) O'Kane & Al-Shehbaz (=Cardaminopsis halleri) using energy-dispersive X-ray microanalysis of frozen-hydrated tissues. Quantitative data were obtained using oxygen as\\u000a an internal standard in the analyses of vacuoles, whereas a peak\\/background ratio method was used for quantification of elements\\u000a in pollen and dehydrated trichomes. Arabidopsis halleri

Hendrik Küpper; Enzo Lombi; Fang-Jie Zhao; Steve P. McGrath

2000-01-01

81

A novel arsenate reductase from the arsenic hyperaccumulating fern Pteris vittata.  

PubMed

Pteris vittata sporophytes hyperaccumulate arsenic to 1% to 2% of their dry weight. Like the sporophyte, the gametophyte was found to reduce arsenate [As(V)] to arsenite [As(III)] and store arsenic as free As(III). Here, we report the isolation of an arsenate reductase gene (PvACR2) from gametophytes that can suppress the arsenate sensitivity and arsenic hyperaccumulation phenotypes of yeast (Saccharomyces cerevisiae) lacking the arsenate reductase gene ScACR2. Recombinant PvACR2 protein has in vitro arsenate reductase activity similar to ScACR2. While PvACR2 and ScACR2 have sequence similarities to the CDC25 protein tyrosine phosphatases, they lack phosphatase activity. In contrast, Arath;CDC25, an Arabidopsis (Arabidopsis thaliana) homolog of PvACR2 was found to have both arsenate reductase and phosphatase activities. To our knowledge, PvACR2 is the first reported plant arsenate reductase that lacks phosphatase activity. CDC25 protein tyrosine phosphatases and arsenate reductases have a conserved HCX5R motif that defines the active site. PvACR2 is unique in that the arginine of this motif, previously shown to be essential for phosphatase and reductase activity, is replaced with a serine. Steady-state levels of PvACR2 expression in gametophytes were found to be similar in the absence and presence of arsenate, while total arsenate reductase activity in P. vittata gametophytes was found to be constitutive and unaffected by arsenate, consistent with other known metal hyperaccumulation mechanisms in plants. The unusual active site of PvACR2 and the arsenate reductase activities of cell-free extracts correlate with the ability of P. vittata to hyperaccumulate arsenite, suggesting that PvACR2 may play an important role in this process. PMID:16766666

Ellis, Danielle R; Gumaelius, Luke; Indriolo, Emily; Pickering, Ingrid J; Banks, Jo Ann; Salt, David E

2006-06-09

82

Hyperaccumulator Alyssum murale Relies on a Different Metal Storage Mechanism for Cobalt than for Nickel  

SciTech Connect

The nickel (Ni) hyperaccumulator Alyssum murale has been developed as a commercial crop for phytoremediation/phytomining Ni from metal-enriched soils. Here, metal co-tolerance, accumulation and localization were investigated for A. murale exposed to metal co-contaminants. A. murale was irrigated with Ni-enriched nutrient solutions containing basal or elevated concentrations of cobalt (Co) or zinc (Zn). Metal localization and elemental associations were investigated in situ with synchrotron X-ray microfluorescence (SXRF) and computed-microtomography (CMT). A. murale hyperaccumulated Ni and Co (> 1000 {micro}g g{sup -1} dry weight) from mixed-metal systems. Zinc was not hyperaccumulated. Elevated Co or Zn concentrations did not alter Ni accumulation or localization. SXRF images showed uniform Ni distribution in leaves and preferential localization of Co near leaf tips/margins. CMT images revealed that leaf epidermal tissue was enriched with Ni but devoid of Co, that Co was localized in the apoplasm of leaf ground tissue and that Co was sequestered on leaf surfaces near the tips/margins. Cobalt-rich mineral precipitate(s) form on leaves of Co-treated A. murale. Specialized biochemical processes linked with Ni (hyper)tolerance in A. murale do not confer (hyper)tolerance to Co. A. murale relies on a different metal storage mechanism for Co (exocellular sequestration) than for Ni (vacuolar sequestration).

Tappero, R.; Peltier, E; Grafe, M; Heidel, K; Ginder-Vogel, M; Livi, K; Rivers, M; Marcus, M; Chaney, R; Sparks, D

2007-01-01

83

A more complete picture of metal hyperaccumulation through next-generation sequencing technologies  

PubMed Central

The mechanistic understanding of metal hyperaccumulation has benefitted immensely from the use of molecular genetics tools developed for Arabidopsis thaliana. The revolution in DNA sequencing will enable even greater strides in the near future, this time not restricted to the family Brassicaceae. Reference genomes are within reach for many ecologically interesting species including heterozygous outbreeders. They will allow deep RNA-seq transcriptome studies and the re-sequencing of contrasting individuals to unravel the genetic basis of phenotypic variation. Cell-type specific transcriptome analyses, which will be essential for the dissection of metal translocation pathways in hyperaccumulators, can be achieved through the combination of RNA-seq and translatome approaches. Affordable high-resolution genotyping of many individuals enables the elucidation of quantitative trait loci in intra- and interspecific crosses as well as through genome-wide association mapping across large panels of accessions. Furthermore, genome-wide scans have the power to detect loci under recent selection. Together these approaches will lead to a detailed understanding of the evolutionary path towards the emergence of hyperaccumulation traits.

Verbruggen, Nathalie; Hanikenne, Marc; Clemens, Stephan

2013-01-01

84

A more complete picture of metal hyperaccumulation through next-generation sequencing technologies.  

PubMed

The mechanistic understanding of metal hyperaccumulation has benefitted immensely from the use of molecular genetics tools developed for Arabidopsis thaliana. The revolution in DNA sequencing will enable even greater strides in the near future, this time not restricted to the family Brassicaceae. Reference genomes are within reach for many ecologically interesting species including heterozygous outbreeders. They will allow deep RNA-seq transcriptome studies and the re-sequencing of contrasting individuals to unravel the genetic basis of phenotypic variation. Cell-type specific transcriptome analyses, which will be essential for the dissection of metal translocation pathways in hyperaccumulators, can be achieved through the combination of RNA-seq and translatome approaches. Affordable high-resolution genotyping of many individuals enables the elucidation of quantitative trait loci in intra- and interspecific crosses as well as through genome-wide association mapping across large panels of accessions. Furthermore, genome-wide scans have the power to detect loci under recent selection. Together these approaches will lead to a detailed understanding of the evolutionary path towards the emergence of hyperaccumulation traits. PMID:24098304

Verbruggen, Nathalie; Hanikenne, Marc; Clemens, Stephan

2013-10-01

85

[Characteristics of 23 species of weed in northeast of China hyperaccumulating PAHs in contaminated soils].  

PubMed

Pot experiments were conducted to investigate the 23 species of weed accumulation characteristics of phenanthrene, as a representative of polycyclic aromatic hydrocarbons (PAHs), from soil in the northeast of China. The result indicated that among the 23 species, the bioconcentration factors of Taraxacum ohwianum K., Potentilla aiscolor B. and Chelidonium majus L. were all higher than 1, which were 1.01, 4.98, 38.24 respectively. The phenanthrene concentrations in roots were 2.83, 16.34 and 9.66 mg/kg which were lower than those in aboveground part with phenanthrene concentrations were 15.18, 74.70 and 573.62 mg/kg, respectively. The hyperaccumulators were indicated by strong conveyance of phenanthrene from root to aboveground part. The analysis of phenanthrene concentration in aboveground weed and aboveground plant biomass showed that the accumulation of phenanthrene in plant were not correlated with their biomass. It concluded that Taraxacum ohwianum K., Potentilla aiscolor B. and Chelidonium majus L. had hyperaccumulative characteristics of phenanthrene, and it is possible to screen out plants with high biomass and hyperaccumulation capability. PMID:22279928

Zhang, Min; Liang, Hong; Gao, Da-Wen; Zhang, Bai-Hui; Li, Xin-Ping; Guo, Xiao-Hu

2011-10-01

86

The potential of phytoremediation using hyperaccumulator plants: a case study at a lead-zinc mine site.  

PubMed

Contamination with heavy metals is one of the most pressing threats to water and soil resources, as well as human health. Phytoremediation might potentially be used to remediate metal-contaminated sites. A major advance in the development of phytoremediation for heavy metal affected soils was the discovery of heavy metal hyperaccumulation in plants. This study applied several established criteria to identify hyperaccumulator plants. A case study was conducted at a mining area in the Hamedan province in the west central region of Iran. The results indicated that plant metal accumulation differed among species and plant parts. Plant species grown in substrata with elevated metal levels contained significantly higher metal levels. Using the most common criteria, Euphorbia macroclada and Centaurea virgata can be classified as hyperaccumulators of specific heavy metals measured in this study and they might potentially be used for the phytoremediation of contaminated soils. PMID:22908644

Lorestani, Bahareh; Cheraghi, Mehrdad; Yousefi, Nafiseh

2012-09-01

87

Constitutively High Expression of the Histidine Biosynthetic Pathway Contributes to Nickel Tolerance in Hyperaccumulator PlantsW?  

PubMed Central

Plants that hyperaccumulate Ni exhibit an exceptional degree of Ni tolerance and the ability to translocate Ni in large amounts from root to shoot. In hyperaccumulator plants in the genus Alyssum, free His is an important Ni binding ligand that increases in the xylem proportionately to root Ni uptake. To determine the molecular basis of the His response and its contribution to Ni tolerance, transcripts representing seven of the eight enzymes involved in His biosynthesis were investigated in the hyperaccumulator species Alyssum lesbiacum by RNA gel blot analysis. None of the transcripts changed in abundance in either root or shoot tissue when plants were exposed to Ni, but transcript levels were constitutively higher in A. lesbiacum than in the congeneric nonaccumulator A. montanum, especially for the first enzyme in the biosynthetic pathway, ATP-phosphoribosyltransferase (ATP-PRT). Comparison with the weak hyperaccumulator A. serpyllifolium revealed a close correlation between Ni tolerance, root His concentration, and ATP-PRT transcript abundance. Overexpression of an A. lesbiacum ATP-PRT cDNA in transgenic Arabidopsis thaliana increased the pool of free His up to 15-fold in shoot tissue, without affecting the concentration of any other amino acid. His-overproducing lines also displayed elevated tolerance to Ni but did not exhibit increased Ni concentrations in either xylem sap or shoot tissue, suggesting that additional factors are necessary to recapitulate the complete hyperaccumulator phenotype. These results suggest that ATP-PRT expression plays a major role in regulating the pool of free His and contributes to the exceptional Ni tolerance of hyperaccumulator Alyssum species.

Ingle, Robert A.; Mugford, Sam T.; Rees, Jonathan D.; Campbell, Malcolm M.; Smith, J. Andrew C.

2005-01-01

88

Tandem Quadruplication of HMA4 in the Zinc (Zn) and Cadmium (Cd) Hyperaccumulator Noccaea caerulescens  

PubMed Central

Zinc (Zn) and cadmium (Cd) hyperaccumulation may have evolved twice in the Brassicaceae, in Arabidopsis halleri and in the Noccaea genus. Tandem gene duplication and deregulated expression of the Zn transporter, HMA4, has previously been linked to Zn/Cd hyperaccumulation in A. halleri. Here, we tested the hypothesis that tandem duplication and deregulation of HMA4 expression also occurs in Noccaea. A Noccaea caerulescens genomic library was generated, containing 36,864 fosmid pCC1FOS™ clones with insert sizes ?20–40 kbp, and screened with a PCR-generated HMA4 genomic probe. Gene copy number within the genome was estimated through DNA fingerprinting and pooled fosmid pyrosequencing. Gene copy numbers within individual clones was determined by PCR analyses with novel locus specific primers. Entire fosmids were then sequenced individually and reads equivalent to 20-fold coverage were assembled to generate complete whole contigs. Four tandem HMA4 repeats were identified in a contiguous sequence of 101,480 bp based on sequence overlap identities. These were flanked by regions syntenous with up and downstream regions of AtHMA4 in Arabidopsis thaliana. Promoter-reporter ?-glucuronidase (GUS) fusion analysis of a NcHMA4 in A. thaliana revealed deregulated expression in roots and shoots, analogous to AhHMA4 promoters, but distinct from AtHMA4 expression which localised to the root vascular tissue. This remarkable consistency in tandem duplication and deregulated expression of metal transport genes between N. caerulescens and A. halleri, which last shared a common ancestor >40 mya, provides intriguing evidence that parallel evolutionary pathways may underlie Zn/Cd hyperaccumulation in Brassicaceae.

O Lochlainn, Seosamh; Bowen, Helen C.; Fray, Rupert G.; Hammond, John P.; King, Graham J.; White, Philip J.; Graham, Neil S.; Broadley, Martin R.

2011-01-01

89

Biomass reduction and arsenic transformation during composting of arsenic-rich hyperaccumulator Pteris vittata L  

Microsoft Academic Search

Background, aim, and scope  Composting is being proposed as a pretreatment step before disposal of metal-rich biomass after phytoextraction process. This\\u000a study determined the biomass reduction and arsenic transformation during composting As-rich biomass of hyperaccumulator Chinese\\u000a brake fern (Pteris vittata L.).\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  High-As fern biomass containing ?4,600 mg As kg?1 was composted for 120 days in a laboratory-scale composter under aerated condition.

Xinde Cao; Lena Ma; Aziz Shiralipour; Willie Harris

2010-01-01

90

Nickel speciation in the xylem sap of the hyperaccumulator Alyssum serpyllifolium ssp. lusitanicum growing on serpentine soils of northeast Portugal  

Microsoft Academic Search

Nickel speciation was studied in the xylem sap of Alyssum serpyllifolium ssp. lusitanicum, a Ni-hyperaccumulator endemic to the serpentine soils of northeast Portugal. The xylem sap was collected from plants growing in its native habitat and characterized in terms of carboxylic and amino acids content. The speciation of nickel was studied in model and real solutions of xylem sap by

Sheila Alves; Cristina Nabais; Maria de Lurdes Simões Gonçalves; Margarida M. Correia dos Santos

2011-01-01

91

Genetic Diversity of Bacterial Communities of Serpentine Soil and of Rhizosphere of the Nickel-Hyperaccumulator Plant Alyssum bertolonii  

Microsoft Academic Search

Serpentine soils are characterized by high levels of heavy metals (Ni, Co, Cr), and low levels of important plant nutrients (P, Ca, N). Because of these inhospitable edaphic conditions, serpentine soils are typically home to a very specialized flora including endemic species as the nickel hyperaccumulator Alyssum bertolonii. Although much is known about the serpentine flora, few researches have investigated

A. Mengoni; E. Grassi; R. Barzanti; E. G. Biondi; C. Gonnelli; C. K. Kim; M. Bazzicalupo

2004-01-01

92

The hyperaccumulator Alyssum murale uses complexation with nitrogen and oxygen donor ligands for Ni transport and storage  

Microsoft Academic Search

The Kotodesh genotype of the nickel (Ni) hyperaccumulator Alyssum murale was examined to determine the compartmentalization and internal speciation of Ni, and other elements, in an effort to ascertain the mechanism used by this plant to tolerate extremely high shoot (stem and leaf) Ni concentrations. Plants were grown either hydroponically or in Ni enriched soils from an area surrounding an

David H. McNear Jr; Rufus L. Chaney; Donald L. Sparks

2009-01-01

93

Developmental and induced responses of nickel-based and organic defences of the nickel-hyperaccumulating shrub, Psychotria douarrei  

Microsoft Academic Search

Summary • Developmental and inducible changes in metal-based (nickel (Ni)) and organic defences (phenolics) are compared in the Ni-hyperaccumulating shrub, Psychotria douarrei . • Young and old leaves of P. douarrei shrubs, subjected to different degrees of simulated herbivory, were analyzed for metals, tannins, macronutrients and total carbon, and compared with a co-occuring nonhyperaccumulator shrub, Ficus webbiana . • Leaf

Micheal A. Davis; Seth G. Pritchard; Robert S. Boyd; Stephen A. Prior

2001-01-01

94

A quantitative trait loci analysis of zinc hyperaccumulation in Arabidopsis halleri.  

PubMed

The mechanisms of metal hyperaccumulation are still not understood, so we conducted a quantitative trait locus (QTL) analysis of zinc (Zn) hyperaccumulation in Arabidopsis halleri, in a cross between this and its sister species, A. petraea, in order to determine the number and approximate location of the genomic regions significantly contributing to this adaptation. An F2 cross between the two species was made, and the leaf Zn concentration of 92 individuals was measured at both low (10 microm) and high (100 microm) Zn concentrations. Twenty-five markers were established that were distributed on all of the eight chromosomes. Mapping of the markers established that they were essentially collinear with previous studies. QTLs exceeding a logarithm to the base 10 of the odds (LOD) value of 3 were found on chromosomes 4 (low Zn), 6 (high Zn) and 7 (both high and low Zn). Evidence for a QTL on chromosome 3 (low Zn) was also found. This analysis validates a previously used method of QTL analysis, based on microarray analysis of segregating families. Genes that have altered during the evolution of this character should also be QTL: this analysis calls into question a number of candidate genes from consideration as such primary genes because they do not appear to be associated with QTLs. PMID:17447913

Filatov, Victor; Dowdle, John; Smirnoff, Nicholas; Ford-Lloyd, Brian; Newbury, H John; Macnair, Mark R

2007-01-01

95

Cellular Sequestration of Cadmium in the Hyperaccumulator Plant Species Sedum alfredii  

SciTech Connect

Spatial imaging of cadmium (Cd) in the hyperaccumulator Sedum alfredii was investigated in vivo by laser ablation inductively coupled plasma mass spectrometry and x-ray microfluorescence imaging. Preferential Cd accumulation in the pith and cortex was observed in stems of the Cd hyperaccumulating ecotype (HE), whereas Cd was restricted to the vascular bundles in its contrasting nonhyperaccumulating ecotype. Cd concentrations of up to 15,000 {micro}g g{sup -1} were measured in the pith cells, which was many fold higher than the concentrations in the stem epidermis and vascular bundles in the HE plants. In the leaves of the HE, Cd was mainly localized to the mesophyll and vascular cells rather than the epidermis. The distribution pattern of Cd in both stems and leaves of the HE was very similar to calcium but not zinc, irrespective of Cd exposure levels. Extended x-ray absorption fine structure spectroscopy analysis showed that Cd in the stems and leaves of the HE was mainly associated with oxygen ligands, and a larger proportion (about 70% in leaves and 47% in stems) of Cd was bound with malic acid, which was the major organic acid in the shoots of the plants. These results indicate that a majority of Cd in HE accumulates in the parenchyma cells, especially in stems, and is likely associated with calcium pathways and bound with organic acid (malate), which is indicative of a critical role of vacuolar sequestration of Cd in the HE S. alfredii.

Tian, Shengke; Lu, Lingli; Labavitch, John M.; Yang, Xiaoe; He, Zhenli; Hu, Hening; Sarangi, Ritimukta; Newville, Matt; Commisso, Joel; Brown, Patrick Hugh (UCD); (SLAC); (Zhejiang); (FSU); (UC)

2012-07-23

96

Spatial Imaging, Speciation, and Quantification of Selenium in theHyperaccumulator Plants Astragalus bisulcatus and Stanleya pinnata  

SciTech Connect

Astragalus bisulcatus and Stanleya pinnata hyperaccumulate selenium (Se) up to 1% of plant dry weight. In the field, Se was mostly present in the young leaves and reproductive tissues of both hyperaccumulators. Microfocused scanning x-ray fluorescence mapping revealed that Se was hyperaccumulated in trichomes in young leaves of A. bisulcatus. None of 10 other elements tested were accumulated in trichomes. Micro x-ray absorption spectroscopy and liquid chromatography-mass spectrometry showed that Se in trichomes was present in the organic forms methylselenocysteine (MeSeCys; 53%) and {gamma}-glutamyl-MeSeCys (47%). In the young leaf itself, there was 30% inorganic Se (selenate and selenite) in addition to 70% MeSeCys. In young S. pinnata leaves, Se was highly concentrated near the leaf edge and surface in globular structures that were shown by energy-dispersive x-ray microanalysis to be mainly in epidermal cells. Liquid chromatography-mass spectrometry revealed both MeSeCys (88%) and selenocystathionine (12%) inside leaf edges. In contrast, both the Se accumulator Brassica juncea and the nonaccumulator Arabidopsis thaliana accumulated Se in their leaf vascular tissues and mesophyll cells. Se in hyperaccumulators appears to be mobile in both the xylem and phloem because Se-treated S. pinnata was found to be highly toxic to phloem-feeding aphids, and MeSeCys was present in the vascular tissues of a S. pinnata young leaf petiole as well as in guttation fluid. The compartmentation of organic selenocompounds in specific storage areas in the plant periphery appears to be a unique property of Se hyperaccumulators. The high concentration of Se in the plant periphery may contribute to Se tolerance and may also serve as an elemental plant defense mechanism.

Freeman, J.L.; Zhang, L.H.; Marcus, M.A.; Fakra, S.; McGrath,S.P.; Pilon-Smits, E.A.H.

2006-09-01

97

Root responses to soil Ni heterogeneity in a hyperaccumulator and a non-accumulator species.  

PubMed

We compared root responses of the Ni-hyperaccumulator plant Berkheya coddii Rossler with the non-accumulator plant Cicer arietinum L. to Ni heterogeneity in soil. We grew plants in growth containers filled with control soil, homogeneously spiked, and heterogeneously spiked soil with Ni concentrations of 62 and 125 mg kg(-1). Neutron radiography (NR) was used to observe the root distribution and the obtained images were analysed to reveal the root volumes in the spiked and unspiked segments of the growth container. There was no significant difference in root distribution pattern of B. coddii among different concentrations of Ni. Unlike B. coddii, the roots of C. arietinum initially grew into the spiked segments. However, the later developing roots did not penetrate the spiked segment suggesting an avoidance strategy. Our results indicate that, B. coddii does not forage towards the Ni-rich patches, although presence of Ni in soil changes its root morphology. PMID:19427726

Moradi, Ahmad B; Conesa, Héctor M; Robinson, Brett H; Lehmann, Eberhard; Kaestner, Anders; Schulin, Rainer

2009-05-09

98

Selenium uptake by edible oyster mushrooms (Pleurotus sp.) from selenium-hyperaccumulated wheat straw.  

PubMed

In an effort to produce selenium (Se)-fortifying edible mushrooms, five species of oyster mushroom (Pleurotus sp.), were cultivated on Se-rich wheat straw collected from a seleniferous belt of Punjab, India. Total selenium was analyzed in the selenium hyperaccumulated wheat straw and the fruiting bodies. Significantly high levels (p<0.0001) of Se uptake were observed in fruiting bodies of all mushrooms grown on Se-rich wheat straw. To the best of our knowledge, accumulation and quantification of selenium in mushrooms has hitherto not been reported with substrates naturally enriched with selenium. The results demonstrate the potential of selenium-rich agricultural residues as substrates for production of Se-enriched mushrooms and the ability of different species of oyster mushrooms to absorb and fortify selenium. The study envisages potential use of selenium-rich agricultural residues towards cultivation of Se-enriched mushrooms for application in selenium supplementation or neutraceutical preparations. PMID:23535542

Bhatia, Poonam; Prakash, Ranjana; Prakash, N Tejo

2013-01-01

99

Effects of compost and phosphate amendments on arsenic mobility in soils and arsenic uptake by the hyperaccumulator, Pteris vittata L  

Microsoft Academic Search

Chinese brake fern (Pteris vittata L.), an arsenic (As) hyperaccumulator, has shown the potential to remediate As-contaminated soils. This study investigated the effects of soil amendments on the leachability of As from soils and As uptake by Chinese brake fern. The ferns were grown for 12 weeks in a chromated–copper–arsenate (CCA) contaminated soil or in As spiked contaminated (ASC) soil.

Xinde Cao; Lena Q. Ma; Aziz Shiralipour

2003-01-01

100

Arsenic species in an arsenic hyperaccumulating fern, Pityrogramma calomelanos: a potential phytoremediator of arsenic-contaminated soils  

Microsoft Academic Search

The fern Pityrogramma calomelanos is a hyperaccumulator of arsenic that grows readily on arsenic-contaminated soils in the Ron Phibun district of southern Thailand. P. calomelanos accumulates arsenic mostly in the fronds (up to 8350 ?g As g?1 dry mass) while the rhizoids contain the lowest concentrations of arsenic (88–310 ?g As g?1 dry mass). The arsenic species in aqueous extracts

Kevin Francesconi; Pornsawan Visoottiviseth; Weeraphan Sridokchan; Walter Goessler

2002-01-01

101

Arbuscular mycorrhiza of Berkheya coddii and other Ni-hyperaccumulating members of Asteraceae from ultramafic soils in South Africa  

Microsoft Academic Search

The occurrence of arbuscular mycorrhiza (AM) in nickel-(Ni)-hyperaccumulating plants of the Asteraceae family growing on Ni-enriched ultramafic soils in South Africa was surveyed. All plants were found to be consistently colonised by AM fungi, with the abundant formation of arbuscules. Berkheya coddii, which is an important species for phytomining, formed well-developed mycorrhiza under greenhouse conditions. Plants cultivated under greenhouse conditions

Katarzyna Turnau; Jolanta Mesjasz-Przybylowicz

2003-01-01

102

Seed germination of a newly discovered hyperaccumulator Solanum nigrum L. affected by illumination and seed-soaking reagent  

Microsoft Academic Search

Solanum nigrum is a newly found Cd-hyperaccumulator which showed very high remediation efficiency in polluted soil. Seed germination experiments with different illumination and seed-soaking reagents were conducted in constant temperature box and greenhouse with soil as burgeon base. The results showed that the germination rate with alternating light\\/dark photoperiod was about twice of that without lighting (p<0.05), suggesting that illumination

Shuhe Wei; Yahu Hu; Mrittunjai Srivastava; Qixing Zhou; Rongcheng Niu; Yunmeng Li; Zhijie Wu; Tieheng Sun

2009-01-01

103

Molecular characterization of endophytic bacteria from metal hyperaccumulator aquatic plant (Eichhornia crassipes) and its role in heavy metal removal  

Microsoft Academic Search

In this study, among a collection of heavy metals resistant endophytic bacterial strains isolated from aquatic hyperaccumulator plant (Eichhornia crassipes), one plant growth promoting endophytic bacteria (PGPE), SVUB4 was selected for what based on their ability to utilize 1-aminocyclopropane-1-carboxylic acid (ACC) as the sole N source and accumulate different heavy metals. The SVUB4 strain was characterized as Enterobacter sp., on

Bahig El-Deeb; Youssuf Gherbawy; Sabry Hassan

2012-01-01

104

Isolation and characterization endophytic bacteria from hyperaccumulator Sedum alfredii Hance and their potential to promote phytoextraction of zinc polluted soil  

Microsoft Academic Search

The aim of this study was to isolate and characterize endophytic bacteria from roots, stems and leaves of Zn\\/Cd hyperaccumulator\\u000a Sedum alfredii. Endophytic bacteria were observed in roots, stems and leave of S. alfredii, with a significantly higher density in roots, followed by leave and stems. A total of fourteen bacterial endophytes were\\u000a isolated and are closely related phylogenetically to

Long Xinxian; Chen Xuemei; Chen Yagang; Wong Jonathan Woon-Chung; Wei Zebin; Wu Qitang

2011-01-01

105

Hyperaccumulation of lead, zinc, and cadmium in plants growing on a lead\\/zinc outcrop in Yunnan Province, China  

Microsoft Academic Search

A field survey was conducted to identify potential hyperaccumulators of Pb, Zn or Cd in the Beichang Pb\\/Zn mine outcrop in\\u000a Yunnan Province, China. The average total concentrations of Pb, Zn, and Cd in the soils were up to 28,438, 5,109, and 52 mg kg?1, respectively. A total of 68 plant species belonging to 60 genera of 37 families naturally colonizing the

S. L. Wang; W. B. Liao; F. Q. Yu; B. Liao; W. S. Shu

2009-01-01

106

Copper changes the yield and cadmium/zinc accumulation and cellular distribution in the cadmium/zinc hyperaccumulator Sedum plumbizincicola.  

PubMed

Non-accumulated metals in mixed metal contaminated soils may affect hyperaccumulator growth and metal accumulation and thus remediation efficiency. Two hydroponics experiments were conducted to investigate the effects of copper (Cu) on cadmium (Cd) and zinc (Zn) accumulation by the Cd/Zn hyperaccumulator Sedum plumbizincicola, Cu toxicity and plant detoxification using chemical sequential extraction of metals, sub-cellular separation, micro synchrotron radiation based X-ray fluorescence, and transmission electron microscopy. Compared with the control (0.31?M Cu), 5-50?M Cu had no significant effect on Cd/Zn accumulation, but Cu at 200?M induced root cell plasmolysis and disordered chloroplast structure. The plants held Cu in the roots and cell walls and complexed Cu in insoluble forms as their main detoxification mechanisms. Exposure to 200?M Cu for 4 days inhibited plant Cd uptake and translocation but did not affect Zn concentrations in roots and stems. Moreover, unloading of Cd and Zn from stem to leaf was restrained compared to control plants, perhaps due to Cu accumulation in leaf veins. Copper may thus interfere with root Cd uptake and restrain Cd/Zn unloading to the leaves. Further investigation of how Cu affects plant metal uptake may help elucidate the Cd/Zn hyper-accumulating mechanisms of S. plumbizincicola. PMID:23959253

Li, Zhu; Wu, Longhua; Hu, Pengjie; Luo, Yongming; Christie, Peter

2013-08-01

107

Difference of toxicity and accumulation of methylated and inorganic arsenic in arsenic-hyperaccumulating and -hypertolerant plants.  

PubMed

The arsenic (As) hyperaccumulators, Pteris vittata and Pteris cretica and an As-tolerant plant Boehmeria nivea, were selected to compare the toxicity, uptake, and transportation of inorganic arsenate (As(V)) and its methylated counterpart dimethylarsinic acid (DMA). The XANES method was used to elucidate the effect of As species transformation on As toxicity and accumulation characteristics. Significantly higher toxicity and lower accumulation of DMAthan inorganic As(V) was shown in the As hyperaccumulators and the As-tolerant plant. Reduction of As(V) was commonly found in the plants. Arsenic complexation with thiols, which have less mobility in plants and usually occur in As-tolerant plants, was also found in rhizoids of P. cretica. Plants with greater ability to form As-thiolate have lower ability for upward transport of As. Demethylation of DMA occurred in the three plants. The DMA component decreased from the rhizoids to the fronds in both hyperaccumulators, while this tendency is reverse in B. nivea. PMID:18754355

Huang, Ze-Chun; Chen, Tong-Bin; Lei, Mei; Liu, Ying-Ru; Hu, Tian-Dou

2008-07-15

108

Quantitative micro-PIXE comparison of elemental distribution in Ni-hyperaccumulating and non-accumulating genotypes of Senecio coronatus  

NASA Astrophysics Data System (ADS)

The Ni hyperaccumulator, plant species Senecio coronalus (Thunb.) Harv., Asteraceae is an example of plant adaptation mechanisms to different ecological conditions. This widespread species can inter alia be found on serpentine outcrops and the genotypes growing in serpentine soils show different ways of adaptation. The populations from two distant localities take up and translocate Ni in concentrations which are normally phytotoxic, while plants growing on a different site, in the vicinity of another hyperaccumulating species, absorb amounts which are typical for most of the plants found on serpentine soils. The NAC nuclear microprobe was used to compare the distribution of Ni and other elements in selected organs and cells with simultaneous use of PIXE and proton BackScattering (BS). Quantitative maps of stems showed large differences in concentrations and distributions of major and trace elements. In hyperaccumulating genotypes Ni is present everywhere within stem tissues, but the highest concentrations were found in the epidermis, cortex and phloem. In non-accumulating plants Ni was concentrated in the phloem. In the leaf epidermis Ni was concentrated in the cell walls for both accumulating and non-accumulating plants. These results suggest that biochemical diversity is more than morphological, because investigated genotypes belong to the same taxon.

Mesjasz-Przybylowicz, J.; Przybylowicz, W. J.; Prozesky, V. M.; Pineda, C. A.

1997-07-01

109

Hormesis phenomena under Cd stress in a hyperaccumulator--Lonicera japonica Thunb.  

PubMed

A hydroponic experiment was carried out to investigate possible hormetic response induced by cadmium (Cd) in a potential hyperaccumulator-Lonicera japonica Thunb. The results showed that Cd at low concentrations induced a significant increase in plant growth, leaf water content and content of photosynthetic pigments in L. japonica, but decreased them at high concentrations, displayed inverted U-shaped dose response curves, confirming a typical biphasic hormetic response. The U-shaped dose response curves were displayed in malondialdehyde (MDA) and electrolyte leakage in leaves at low doses of Cd, indicating reduce oxidative stress and toxic effect. The increase of superoxide dismutase (SOD) and catalase (CAT) activities was observed along with the increased Cd concentration, indicative of increase in anti-oxidative capacity that ensures redox homeostasis is maintained. After 28 days exposure to 10 mg L(-1) Cd, stem and leaf Cd concentrations reached 502.96 ± 28.90 and 103.22 ± 5.62 mg kg(-1) DW, respectively and the plant had high bioaccumulation coefficient (BC) and translocation factor (TF'). Moreover, the maximum TF value was found at 2.5 mg L(-1) Cd treatment, implying that low Cd treatment improved the ability to transfer Cd from medium via roots to aerial structures. Taking together, L. japonica could be considered as a new plant to investigate the underlying mechanisms of hormesis and Cd tolerance. Our results suggest that hormetic effects should be taken into consideration in phytoremediation of Cd-contaminated soil. PMID:23359063

Jia, Lian; He, Xingyuan; Chen, Wei; Liu, Zhouli; Huang, Yanqing; Yu, Shuai

2013-01-29

110

Mycorrhizal colonization affects the elemental distribution in roots of Ni-hyperaccumulator Berkheya coddii Roessler.  

PubMed

The effect of arbuscular mycorrhizal fungi (AMF) on the distribution and concentration of elements in roots of Ni-hyperaccumulating plant Berkheya coddii was studied. Micro-PIXE (particle-induced X-ray emission) analysis revealed significant differences between AMF-inoculated and non-inoculated plants as well as between main and lateral roots. The accumulation of P, K, Mn and Zn in the cortical layer of lateral roots of inoculated plants confirmed the important role of AMF in uptake and accumulation of these elements. Higher concentration of P, K, Fe, Ni, Cu and Zn in the vascular stele in roots of AMF-inoculated plants than in the non-inoculated ones indicates more efficient translocation of these elements to the aboveground parts of the plant. These findings indicate the necessity of including the influence of AMF in studies on the uptake of elements by plants and in industrial use of B. coddii for Ni extraction from polluted soils. PMID:23369753

Or?owska, El?bieta; Przyby?owicz, Wojciech; Orlowski, Dariusz; Mongwaketsi, Nametso P; Turnau, Katarzyna; Mesjasz-Przyby?owicz, Jolanta

2013-01-24

111

Silver release from decomposed hyperaccumulating Amanita solitaria fruit-body biomass strongly affects soil microbial community.  

PubMed

Interaction of Ag with communities of soil saprotrophic organisms was studied in two different soils using a metagenomic approach. Three levels of Ag were applied to the soil samples: 0, 0.008 and 0.505 ?g Ag/g soil. Silver was applied in mineral form as well as naturally bound in dry fruit-body biomass of the Ag-hyperaccumulating ectomycorrhizal fungus Amanita solitaria. Contrasting behavior of fungi and bacteria in reaction to Ag dosages was observed. The majority of bacterial ribotypes tended to prefer the soil with low doses of Ag, the ribotypes of fungi were more abundant in untreated soils and soils treated with the highest Ag concentration. Organically bound and mineral forms of Ag did not differ substantially in their effects on microbes in samples. The results indicate that decomposing Ag-rich fungal biomass can significantly alter the soil microbiota. This can contribute to formation of spot-like non-homogeneities in soil microbial distribution. PMID:22684239

Gryndler, Milan; Hršelová, Hana; Soukupová, Lucie; Borovi?ka, Jan

2012-06-10

112

Selenium Hyperaccumulator Plants Stanleya pinnata and Astragalus bisulcatus Are Colonized by Se-Resistant, Se-Excluding Wasp and Beetle Seed Herbivores  

PubMed Central

Selenium (Se) hyperaccumulator plants can concentrate the toxic element Se up to 1% of shoot (DW) which is known to protect hyperaccumulator plants from generalist herbivores. There is evidence for Se-resistant insect herbivores capable of feeding upon hyperaccumulators. In this study, resistance to Se was investigated in seed chalcids and seed beetles found consuming seeds inside pods of Se-hyperaccumulator species Astragalus bisulcatus and Stanleya pinnata. Selenium accumulation, localization and speciation were determined in seeds collected from hyperaccumulators in a seleniferous habitat and in seed herbivores. Astragalus bisulcatus seeds were consumed by seed beetle larvae (Acanthoscelides fraterculus Horn, Coleoptera: Bruchidae) and seed chalcid larvae (Bruchophagus mexicanus, Hymenoptera: Eurytomidae). Stanleya pinnata seeds were consumed by an unidentified seed chalcid larva. Micro X-ray absorption near-edge structure (µXANES) and micro-X-Ray Fluorescence mapping (µXRF) demonstrated Se was mostly organic C-Se-C forms in seeds of both hyperaccumulators, and S. pinnata seeds contained ?24% elemental Se. Liquid chromatography–mass spectrometry of Se-compounds in S. pinnata seeds detected the C-Se-C compound seleno-cystathionine while previous studies of A. bisulcatus seeds detected the C-Se-C compounds methyl-selenocysteine and ?-glutamyl-methyl-selenocysteine. Micro-XRF and µXANES revealed Se ingested from hyperaccumulator seeds redistributed throughout seed herbivore tissues, and portions of seed C-Se-C were biotransformed into selenocysteine, selenocystine, selenodiglutathione, selenate and selenite. Astragalus bisulcatus seeds contained on average 5,750 µg Se g?1, however adult beetles and adult chalcid wasps emerging from A. bisulcatus seed pods contained 4–6 µg Se g?1. Stanleya pinnata seeds contained 1,329 µg Se g?1 on average; however chalcid wasp larvae and adults emerging from S. pinnata seed pods contained 9 and 47 µg Se g?1. The results suggest Se resistant seed herbivores exclude Se, greatly reducing tissue accumulation; this explains their ability to consume high-Se seeds without suffering toxicity, allowing them to occupy the unique niche offered by Se hyperaccumulator plants.

Freeman, John L.; Marcus, Matthew A.; Fakra, Sirine C.; Devonshire, Jean; McGrath, Steve P.; Quinn, Colin F.; Pilon-Smits, Elizabeth A. H.

2012-01-01

113

Selenium hyperaccumulator plants Stanleya pinnata and Astragalus bisulcatus are colonized by Se-resistant, Se-excluding wasp and beetle seed herbivores.  

PubMed

Selenium (Se) hyperaccumulator plants can concentrate the toxic element Se up to 1% of shoot (DW) which is known to protect hyperaccumulator plants from generalist herbivores. There is evidence for Se-resistant insect herbivores capable of feeding upon hyperaccumulators. In this study, resistance to Se was investigated in seed chalcids and seed beetles found consuming seeds inside pods of Se-hyperaccumulator species Astragalus bisulcatus and Stanleya pinnata. Selenium accumulation, localization and speciation were determined in seeds collected from hyperaccumulators in a seleniferous habitat and in seed herbivores. Astragalus bisulcatus seeds were consumed by seed beetle larvae (Acanthoscelides fraterculus Horn, Coleoptera: Bruchidae) and seed chalcid larvae (Bruchophagus mexicanus, Hymenoptera: Eurytomidae). Stanleya pinnata seeds were consumed by an unidentified seed chalcid larva. Micro X-ray absorption near-edge structure (µXANES) and micro-X-Ray Fluorescence mapping (µXRF) demonstrated Se was mostly organic C-Se-C forms in seeds of both hyperaccumulators, and S. pinnata seeds contained ?24% elemental Se. Liquid chromatography-mass spectrometry of Se-compounds in S. pinnata seeds detected the C-Se-C compound seleno-cystathionine while previous studies of A. bisulcatus seeds detected the C-Se-C compounds methyl-selenocysteine and ?-glutamyl-methyl-selenocysteine. Micro-XRF and µXANES revealed Se ingested from hyperaccumulator seeds redistributed throughout seed herbivore tissues, and portions of seed C-Se-C were biotransformed into selenocysteine, selenocystine, selenodiglutathione, selenate and selenite. Astragalus bisulcatus seeds contained on average 5,750 µg Se g(-1), however adult beetles and adult chalcid wasps emerging from A. bisulcatus seed pods contained 4-6 µg Se g(-1). Stanleya pinnata seeds contained 1,329 µg Se g(-1) on average; however chalcid wasp larvae and adults emerging from S. pinnata seed pods contained 9 and 47 µg Se g(-1). The results suggest Se resistant seed herbivores exclude Se, greatly reducing tissue accumulation; this explains their ability to consume high-Se seeds without suffering toxicity, allowing them to occupy the unique niche offered by Se hyperaccumulator plants. PMID:23226523

Freeman, John L; Marcus, Matthew A; Fakra, Sirine C; Devonshire, Jean; McGrath, Steve P; Quinn, Colin F; Pilon-Smits, Elizabeth A H

2012-12-03

114

Effects of bacteria on cadmium bioaccumulation in the cadmium hyperaccumulator plant Beta vulgaris var. cicla L.  

PubMed

To investigate the effects of two cadmium-tolerant bacteria, Staphylococcus pasteuri (S. pasteuri X1) and Agrobacterium tumefaciens (A. tumefaciens X2), on cadmium uptake by the cadmium hyperaccumulator plant Beta vulgaris var. cicla L., a pot experiment with artificially contaminated soil was conducted. The results demonstrated that both cadmium-tolerant bacteria enhanced the dry weight of Beta vulgaris var. cicla L. The total dry weights of plants in the control CK20, S. pasteuri X1 and A. tumefaciens X2 treatments were 0.85, 1.13, and 1.38 g/pot, respectively. Compared with the control CK20 findings, the total dry weight of plants was increased by 32.8 and 61.1% after inoculation with S. pasteuri X1 and A. tumefaciens X2, respectively, indicating that A. tumefaciens X2 more strongly promoted the growth of Beta vulgaris var. cicla L. than S. pasteuri X1. In addition, inoculation with S. pasteuri X1 and A. tumefaciens X2 significantly (p < 0.05) promoted cadmium uptake by plants and improved the bioaccumulation of cadmium by the plants from the soil. Moreover, the inoculation of S. pasteuri X1 and A. tumefaciens X2 effectively facilitated the transfer of cadmium in the soil from the Fe-Mn oxide and residual fractions to the soluble plus exchangeable and weakly specially adsorbed fractions in the rhizosphere soils of plants. The bacterial enhancement of cadmium phytoavailability might provide a potential and promising method to increase the efficiency of phytoextraction. PMID:23488173

Chen, Su; Chao, Lei; Sun, Lina; Sun, Tieheng

2013-01-01

115

Soil pollution assessment and identification of hyperaccumulating plants in chromated copper arsenate (CCA) contaminated sites, Korea.  

PubMed

In recent decades, heavy metal contamination in soil adjacent to chromated copper arsenate (CCA) treated wood has received increasing attention. This study was conducted to determine the pollution level (PL) based on the concentrations of Cr, Cu and As in soils and to evaluate the remediative capacity of native plant species grown in the CCA contaminated site, Gangwon Province, Korea. The pollution index (PI), integrated pollution index (IPI), bioaccumulation factors (BAF(shoots) and BAF(roots)) and translocation factor (TF) were determined to ensure soil contamination and phytoremediation availability. The 19 soil samples from 10 locations possibly contaminated with Cr, Cu and As were collected. The concentrations of Cr, Cu and As in the soil samples ranged from 50.56-94.13 mg kg(-1), 27.78-120.83 mg kg(-1), and 0.13-9.43 mg kg(-1), respectively. Generally, the metal concentrations decreased as the distance between the CCA-treated wood structure and sampling point increased. For investigating phytoremediative capacity, the 19 native plant species were also collected in the same area with soil samples. Our results showed that only one plant species of Iris ensata, which presented the highest accumulations of Cr (1120 mg kg(-1)) in its shoot, was identified as a hyperaccumulator. Moreover, the relatively higher values of BAF(shoot) (3.23-22.10) were observed for Typha orientalis, Iris ensata and Scirpus radicans Schk, suggesting that these plant species might be applicable for selective metal extraction from the soils. For phytostabilization, the 15 plant species with BAF(root) values>1 and TF values<1 were suitable; however, Typha orientalis was the best for Cr. PMID:22342337

Usman, Adel R A; Lee, Sang Soo; Awad, Yasser M; Lim, Kyoung Jae; Yang, Jae E; Ok, Yong Sik

2012-02-17

116

Characterization of Ni-resistant bacteria in the rhizosphere of the hyperaccumulator alyssum murale by 16S RRNA gene sequence analysis  

Technology Transfer Automated Retrieval System (TEKTRAN)

The diversity of 184 isolates from rhizosphere and bulk soil samples taken from the hyperaccumulator Alyssum murale, grown in a Ni-rich serpentine soil, was determined by 16S rRNA gene analysis. Among these 184 isolates 44 groups were identified. The 16S rRNA gene sequences of representatives were ...

117

Characterization of Arsenate Reductase in the Extract of Roots and Fronds of Chinese Brake Fern, an Arsenic Hyperaccumulator1  

PubMed Central

Root extracts from the arsenic (As) hyperaccumulating Chinese brake fern (Pteris vittata) were shown to be able to reduce arsenate to arsenite. An arsenate reductase (AR) in the fern showed a reaction mechanism similar to the previously reported Acr2p, an AR from yeast (Saccharomyces cerevisiae), using glutathione as the electron donor. Substrate specificity as well as sensitivity toward inhibitors for the fern AR (phosphate as a competitive inhibitor, arsenite as a noncompetitive inhibitor) was also similar to Acr2p. Kinetic analysis showed that the fern AR had a Michaelis constant value of 2.33 mm for arsenate, 15-fold lower than the purified Acr2p. The AR-specific activity of the fern roots treated with 2 mm arsenate for 9 d was at least 7 times higher than those of roots and shoots of plant species that are known not to tolerate arsenate. A T-DNA knockout mutant of Arabidopsis (Arabidopsis thaliana) with disruption in the putative Acr2 gene had no AR activity. We could not detect AR activity in shoots of the fern. These results indicate that (1) arsenite, the previously reported main storage form of As in the fern fronds, may come mainly from the reduction of arsenate in roots; and (2) AR plays an important role in the detoxification of As in the As hyperaccumulating fern.

Duan, Gui-Lan; Zhu, Yong-Guan; Tong, Yi-Ping; Cai, Chao; Kneer, Ralf

2005-01-01

118

Complexation with dissolved organic matter and mobility control of heavy metals in the rhizosphere of hyperaccumulator Sedum alfredii.  

PubMed

The complexation of Zn, Cd and Pb with dissolved organic matter (DOM) in the rhizosphere of hyperaccumulating ecotype (HE) and a non-hyperaccumulating ecotype (NHE) of Sedum alfredii was measured using resin equilibration method. After the growth of HE S. alfredii, the rhizosphere soil pH was reduced by 0.27-0.33 units, due to enhanced DOM derived from root exudation. For both ecotypes of S. alfredii, the fraction of free metal as a percentage of soluble metal varied from 22.1 to 42.5% for Zn(2+), from 8.1 to 15.5% for Cd(2+), and from 4.5 to 10.4% for Pb(2+). Resin equilibration experiment results indicated that HE-DOM had greater ability to form complexes with Zn, Cd and Pb than NHE-DOM, Visual MINTEQ model gave excellent predictions of the complexation of Zn and Cd by DOM (R(2) > 0.97). DOM in the rhizosphere of HE S. alfredii could significantly increase metal mobility through the formation of soluble DOM-metal complexes. PMID:23938448

Li, Tingqiang; Tao, Qi; Liang, Chengfeng; Shohag, M J I; Yang, Xiaoe; Sparks, Donald L

2013-08-10

119

Do high-nickel leaves shed by the nickel hyperaccumulator Alyssum murale inhibit seed germination of competing plants?  

PubMed

Elemental allelopathy suggests that nickel (Ni)-rich leaves shed by hyperaccumulators inhibit the germination and growth of nearby plant species. Here, the germination of eight herbaceous species following addition of Alyssum murale biomass or Ni(NO3)2, with the same Ni level added to soil, was assessed. The distribution of Ni in soil was tested by determining Ni phytoavailability and speciation over time. Phytoavailable Ni in soil amended with biomass declined rapidly over time due to Ni binding to iron (Fe)/manganese (Mn) oxides in the soil. No significant effects on seed germination were observed. Unlike the Ni complex in Alyssum biomass, more Ni remained soluble and phytoavailable in soil amended with Ni(NO3)2, thus significantly inhibiting seed germination. High-Ni leaves shed by hyperaccumulators did not appear to create a 'toxic zone' around the plants and inhibit germination or growth of competing plants. The lack of an allelopathic effect was probably related to low Ni availability. PMID:17244045

Zhang, Lan; Angle, J Scott; Chaney, Rufus L

2007-01-01

120

Elucidating the selenium and arsenic metabolic pathways following exposure to the non-hyperaccumulating Chlorophytum comosum, spider plant  

PubMed Central

Although many studies have investigated the metabolism of selenium and arsenic in hyperaccumulating plants for phytoremediation purposes, few have explored non-hyperaccumulating plants as a model for general contaminant exposure to plants. In addition, the result of simultaneous supplementation with selenium and arsenic has not been investigated in plants. In this study, Chlorophytum comosum, commonly known as the spider plant, was used to investigate the metabolism of selenium and arsenic after single and simultaneous supplementation. Size exclusion and ion-pairing reversed phase liquid chromatography were coupled to an inductively coupled plasma mass spectrometer to obtain putative metabolic information of the selenium and arsenic species in C. comosum after a mild aqueous extraction. The chromatographic results depict that selenium and arsenic species were sequestered in the roots and generally conserved upon translocation to the leaves. The data suggest that selenium was directly absorbed by C. comosum roots when supplemented with SeVI, but a combination of passive and direct absorption occurred when supplemented with SeIV due to the partial oxidation of SeIV to SeVI in the rhizosphere. Higher molecular weight selenium species were more prevalent in the roots of plants supplemented with SeIV, but in the leaves of plants supplemented with SeVI due to an increased translocation rate. When supplemented as AsIII, arsenic is proposed to be passively absorbed as AsIII and partially oxidized to AsV in the plant root. Although total elemental analysis demonstrates a selenium and arsenic antagonism, a compound containing selenium and arsenic was not present in the general aqueous extract of the plant.

Afton, Scott E.; Catron, Brittany; Caruso, Joseph A.

2009-01-01

121

Elucidating the selenium and arsenic metabolic pathways following exposure to the non-hyperaccumulating Chlorophytum comosum, spider plant.  

PubMed

Although many studies have investigated the metabolism of selenium and arsenic in hyperaccumulating plants for phytoremediation purposes, few have explored non-hyperaccumulating plants as a model for general contaminant exposure to plants. In addition, the result of simultaneous supplementation with selenium and arsenic has not been investigated in plants. In this study, Chlorophytum comosum, commonly known as the spider plant, was used to investigate the metabolism of selenium and arsenic after single and simultaneous supplementation. Size exclusion and ion-pairing reversed phase liquid chromatography were coupled to an inductively coupled plasma mass spectrometer to obtain putative metabolic information of the selenium and arsenic species in C. comosum after a mild aqueous extraction. The chromatographic results depict that selenium and arsenic species were sequestered in the roots and generally conserved upon translocation to the leaves. The data suggest that selenium was directly absorbed by C. comosum roots when supplemented with Se(VI), but a combination of passive and direct absorption occurred when supplemented with Se(IV) due to the partial oxidation of Se(IV) to Se(VI) in the rhizosphere. Higher molecular weight selenium species were more prevalent in the roots of plants supplemented with Se(IV), but in the leaves of plants supplemented with Se(VI) due to an increased translocation rate. When supplemented as As(III), arsenic is proposed to be passively absorbed as As(III) and partially oxidized to As(V) in the plant root. Although total elemental analysis demonstrates a selenium and arsenic antagonism, a compound containing selenium and arsenic was not present in the general aqueous extract of the plant. PMID:19273464

Afton, Scott E; Catron, Brittany; Caruso, Joseph A

2009-03-08

122

Life history variation in the heavy metal tolerant plant Thlaspi caerulescens growing in a network of contaminated and noncontaminated sites in southern France: role of gene flow, selection and phenotypic plasticity.  

PubMed

* Here we explore life history differences in a set of neighbouring metallicolous and nonmetallicolous populations of the heavy metal tolerant plant Thlaspi caerulescens. * We contrasted data from field observations and from a common garden experiment, in which soil zinc (Zn) concentration and light availability were manipulated, and data on microsatellite molecular variation. * The two ecotypes showed few differences in life history in the field, but large differences in their response to Zn concentration in the common garden. Soil toxicity affected most characters in nonmetallicolous plants, while it had no effect on metallicolous plants. The two ecotypes responded similarly to light. Genetic differentiation for quantitative characters between ecotypes contrasted with the absence of differentiation for microsatellites. Conversely, populations of the same ecotype showed similar responses to Zn, despite their high differentiation for molecular markers. * We conclude that divergent selection related to soil toxicity has had a predominant role in shaping life history differences between ecotypes, gene flow weakly opposing local adaptation despite geographical proximity. PMID:17176406

Jiménez-Ambriz, Georgina; Petit, Christophe; Bourrié, Isabelle; Dubois, Sophie; Olivieri, Isabelle; Ronce, Ophélie

2007-01-01

123

Accumulation of an organic anticancer selenium compound in a transgenic Solanaceous species shows wider applicability of the selenocysteine methyltransferase transgene from selenium hyperaccumulators  

Microsoft Academic Search

Tolerance to high selenium (Se) soils in Se-hyperaccumulating plant species is correlated with the ability to biosynthesise\\u000a methylselenocysteine (MeSeCys), due to the activity of selenocysteine methyltransferase (SMT). In mammals, inclusion of MeSeCys\\u000a in the diet reduces the incidence of certain cancers, so increasing the range of crop plants that can produce this compound\\u000a is an attractive biotechnology target. However, in

Marian J. McKenzie; Donald A. Hunter; Ranjith Pathirana; Lyn M. Watson; Nigel I. Joyce; Adam J. Matich; Daryl D. Rowan; David A. Brummell

2009-01-01

124

Characterization of Ni-resistant bacteria in the rhizosphere of the hyperaccumulator Alyssum murale by 16S rRNA gene sequence analysis  

Microsoft Academic Search

The diversity of 184 isolates from rhizosphere and bulk soil samples taken from the Ni hyperaccumulator Alyssum murale, grown in a Ni-rich serpentine soil, was determined by 16S rRNA gene analysis. Restriction digestion of the 16S rRNA gene\\u000a was used to identify 44 groups. Representatives of each of these groups were placed within the phyla Proteobacteria, Firmicutes and Actinobacteria by

R. A. I. Abou-Shanab; P. van Berkum; J. S. Angle; T. A. Delorme; R. L. Chaney; H. A. Ghozlan; K. Ghanem; H. Moawad

2010-01-01

125

Interactive effects of pH, arsenic and phosphorus on uptake of As and P and growth of the arsenic hyperaccumulator Pteris vittata L. under hydroponic conditions  

Microsoft Academic Search

Arsenic (As)-contaminated soil and water vary with pH and concentrations of As and P. This study examined the effects and interactions of three factors, pH, As and P, on As hyperaccumulator Pteris vittata L. to optimize plant growth and maximize As removal from contaminated sites, especially water. Two sets of hydroponic experiments were conducted using three-factor, five-level central composite design.

S. Tu; L. Q. Ma

2003-01-01

126

Zinc-Dependent Global Transcriptional Control, Transcriptional Deregulation, and Higher Gene Copy Number for Genes in Metal Homeostasis of the Hyperaccumulator Arabidopsis halleri1[W  

PubMed Central

The metal hyperaccumulator Arabidopsis halleri exhibits naturally selected zinc (Zn) and cadmium (Cd) hypertolerance and accumulates extraordinarily high Zn concentrations in its leaves. With these extreme physiological traits, A. halleri phylogenetically belongs to the sister clade of Arabidopsis thaliana. Using a combination of genome-wide cross species microarray analysis and real-time reverse transcription-PCR, a set of candidate genes is identified for Zn hyperaccumulation, Zn and Cd hypertolerance, and the adjustment of micronutrient homeostasis in A. halleri. Eighteen putative metal homeostasis genes are newly identified to be more highly expressed in A. halleri than in A. thaliana, and 11 previously identified candidate genes are confirmed. The encoded proteins include HMA4, known to contribute to root-shoot transport of Zn in A. thaliana. Expression of either AtHMA4 or AhHMA4 confers cellular Zn and Cd tolerance to yeast (Saccharomyces cerevisiae). Among further newly implicated proteins are IRT3 and ZIP10, which have been proposed to contribute to cytoplasmic Zn influx, and FRD3 required for iron partitioning in A. thaliana. In A. halleri, the presence of more than a single genomic copy is a hallmark of several highly expressed candidate genes with possible roles in metal hyperaccumulation and metal hypertolerance. Both A. halleri and A. thaliana exert tight regulatory control over Zn homeostasis at the transcript level. Zn hyperaccumulation in A. halleri involves enhanced partitioning of Zn from roots into shoots. The transcriptional regulation of marker genes suggests that in the steady state, A. halleri roots, but not the shoots, act as physiologically Zn deficient under conditions of moderate Zn supply.

Talke, Ina N.; Hanikenne, Marc; Kramer, Ute

2006-01-01

127

Comparison of gene expression in segregating families identifies genes and genomic regions involved in a novel adaptation, zinc hyperaccumulation.  

PubMed

One of the challenges of comparative genomics is to identify specific genetic changes associated with the evolution of a novel adaptation or trait. We need to be able to disassociate the genes involved with a particular character from all the other genetic changes that take place as lineages diverge. Here we show that by comparing the transcriptional profile of segregating families with that of parent species differing in a novel trait, it is possible to narrow down substantially the list of potential target genes. In addition, by assuming synteny with a related model organism for which the complete genome sequence is available, it is possible to use the cosegregation of markers differing in transcription level to identify regions of the genome which probably contain quantitative trait loci (QTLs) for the character. This novel combination of genomics and classical genetics provides a very powerful tool to identify candidate genes. We use this methodology to investigate zinc hyperaccumulation in Arabidopsis halleri, the sister species to the model plant, Arabidopsis thaliana. We compare the transcriptional profile of A. halleri with that of its sister nonaccumulator species, Arabidopsis petraea, and between accumulator and nonaccumulator F(3)s derived from the cross between the two species. We identify eight genes which consistently show greater expression in accumulator phenotypes in both roots and shoots, including two metal transporter genes (NRAMP3 and ZIP6), and cytoplasmic aconitase, a gene involved in iron homeostasis in mammals. We also show that there appear to be two QTLs for zinc accumulation, on chromosomes 3 and 7. PMID:16911220

Filatov, Victor; Dowdle, John; Smirnoff, Nicholas; Ford-Lloyd, Brian; Newbury, H John; Macnair, Mark R

2006-09-01

128

A new insight into the recycling of hyperaccumulator: synthesis of the mixed Cu and Zn oxide nanoparticles using Brassica juncea L.  

PubMed

The mixed Cu and Zn oxide (Cu/ZnO) nanoparticles have been synthesized using Brassica juncea L. plants. The synthesized Cu/ZnO nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive spectrum (EDS). It was found that the synthesized Cu/ZnO nanoparticles were corresponding to the Cu(0.05)Zn(0.95)O structure. The shapes of the synthesized ZnO nanoparticles were nonuniform, but the CuO nanoparticles showed a spherical shape. The CuO nanoparticles entered in the structures of ZnO nanoparticles. An average size of 97 nm was obtained for Cu(0.05)Zn(0.95)O. The Cu(0.05)Zn(0.95)O nanoparticles were pure. The method for synthesis of Cu(0.05)Zn(0.95)O nanoparticles using Cu hyperaccumulator (B. juncea) plants constitutes a new insight into the recycling of hyperaccumulator and provides a novel route for further development of green nanostructure syntheses. PMID:22908650

Qu, Jiao; Luo, Chunqiu; Cong, Qiao; Yuan, Xing

2012-10-01

129

Growth and Metal Uptake by Plants Grown in Mono and Dual Culture in Metal-contaminated Soils  

Microsoft Academic Search

Plants are able to affect the mobility of heavy metals in the rhizosphere due to root exudates and other mechanisms resulting in a change in their phytoextraction ability. We tested separate (monoculture) and intercropping (dual culture) systems of hyperaccumulator Thlaspi caerulescens and accumulator tree Salix dasyclados in two soils with different levels of contamination. Intercropping did not significantly affect accumulation

Zuzana Fuksová; Ji?ina Száková; Ji?í Balík; Pavel Tlustoš

2010-01-01

130

Identification and validation of heavy metal and radionuclide hyperaccumulating terrestrial plant species. Quarterly technical progress report, March 20, 1997--June 19, 1997  

SciTech Connect

This laboratory has been involved in a collaborative project focusing on a range of issues related to the phytoremediation of heavy metal-and radionuclide- contaminated soils. While much of the research has been fundamental in nature, involving physiological and molecular characterizations of the mechanisms of hyperaccumulation in plants, the laboratory is also investigating more practical issues related to phytoremediation. A central issue in this latter research has been the identification of amendments capable of increasing the bioavailability and subsequent phytoextraction of radionuclides. The results described here detail these efforts for uranium and Cs-137. A study was also conducted on a Cs-137 contaminated site at Brookhaven National Laboratory (BNL), which allowed application of the laboratory and greenhouse results to a field setting.

Kochian, L.

1997-11-01

131

A putative novel role for plant defensins: a defensin from the zinc hyper-accumulating plant, Arabidopsis halleri, confers zinc tolerance.  

PubMed

The metal tolerance of metal hyper-accumulating plants is a poorly understood mechanism. In order to unravel the molecular basis of zinc (Zn) tolerance in the Zn hyper-accumulating plant Arabidopsis halleri ssp. halleri, we carried out a functional screening of an A. halleri cDNA library in the yeast Saccharomyces cerevisiae to search for genes conferring Zn tolerance to yeast cells. The screening revealed four A. halleri defensin genes (AhPDFs), which induced Zn but not cadmium (Cd) tolerance in yeast. The expression of AhPDF1.1 under the control of the 35S promoter in A. thaliana made the transgenic plants more tolerant to Zn than wild-type plants, but did not change the tolerance to Cd, copper (Cu), cobalt (Co), iron (Fe) or sodium (Na). Thus, AhPDF1.1 is able to confer Zn tolerance both to yeast and plants. In A. halleri, defensins are constitutively accumulated at a higher level in shoots than in A. thaliana. A. halleri defensin pools are Zn-responsive, both at the mRNA and protein levels. In A. thaliana, some but not all defensin genes are induced by ZnCl2 treatment, and these genes are not induced by NaCl treatment. Defensins, found in a very large number of organisms, are known to be involved in the innate immune system but have never been found to play any role in metal physiology. Our results support the proposition that defensins could be involved in Zn tolerance in A. halleri, and that a role for plant defensins in metal physiology should be considered. PMID:16792695

Mirouze, Marie; Sels, Jan; Richard, Odile; Czernic, Pierre; Loubet, Stéphanie; Jacquier, Amaury; François, Isabelle E J A; Cammue, Bruno P A; Lebrun, Michel; Berthomieu, Pierre; Marquès, Laurence

2006-06-22

132

Localisation of nickel and mineral nutrients Ca, K, Fe, Mg by Scanning Electron Microscopy microanalysis in tissues of the nickel-hyperaccumulator Alyssum bertolonii Desv. and the non-accumulator Alyssum montanum L  

Microsoft Academic Search

Plants of the nickel-hyperaccumulator Alyssum bertolonii Desv. and of the non-accumulator A. montanum L. growing on a serpentine site in Tuscany, Italy, and plants of A. montanum from a nearby non-serpentine site were analysed for metal concentration and localisation. The leaves of A. bertolonii contained 160 times more nickel than those of A. montanum from the same site, thus demonstrating

M Marmiroli; C Gonnelli; E Maestri; R Gabbrielli; N Marmiroli

2004-01-01

133

Arsenic accumulation pattern in 12 Indian ferns and assessing the potential of Adiantum capillus-veneris, in comparison to Pteris vittata, as arsenic hyperaccumulator.  

PubMed

The present study was undertaken to evaluate the ability of some Indian ferns to accumulate and tolerate arsenic. Twelve species of Indian ferns were exposed to 10 mg L(-1) arsenic as sodium arsenate for 15 days in hydroponic system. Depending on the arsenic uptake in the plant parts--Pteris vittata, Pteris cretica, Adiantum capillus-veneris and Nephrolepis exaltata may be categorised as arsenic accumulator. Further, A. capillus-veneris plants were grown in arsenic contaminated soil (200-600 mg kg(-1)) under green-house condition, to assess its arsenic accumulation and tolerance mechanism, in comparison to known As-hyperaccumulator--P. vittata Linn., growing in the same conditions. The experiment identified A. capillus-veneris having a potential to tolerate arsenic up to 500 mg kg(-1). The plants were analysed for the extent of oxidative stress, as a result of arsenic accumulation. A. capillus-veneris was able to detoxify the arsenic stress through induction of anti-oxidant defence system. PMID:20655204

Singh, Nandita; Raj, Anshita; Khare, P B; Tripathi, R D; Jamil, Sarah

2010-07-22

134

Phytofiltration of arsenic and cadmium from the water environment using Micranthemum umbrosum (J.F. Gmel) S.F Blake as a hyperaccumulator.  

PubMed

Arsenic (As) and cadmium (Cd) pollution in water is an important global issue. Phytofiltration is an eco-friendly technology that helps clean up pollutants using ornamental plants, such as Micranthemum umbrosum (J.F. Gmel) S.F. Blake. After a seven-day hydroponic experiment, M. umbrosum removed 79.3-89.5% As and 60-73.1% Cd from 0 to 1.0 microg As mL(-1) and 0.3 to 30.0 microg Cd mL(-1) solutions, respectively. For As treatment, root to stem and stem to leaf translocation factors greater than 1.0 indicated that accumulation of As in leaves was large compared to that in stem and roots. However, the accumulation of Cd in roots was higher than that in the leaves and stem. In addition, M. umbrosum completely removed Cd within three days from 0.38 to around 0 microg mL(-1) Cd in the solution when the plant was exchanged daily. Bio-concentration factors (2350 for As and 3027 for Cd) for M. umbrosum were higher than for other As and Cd phytoremediators. The results show that M. umbrosum can be an effective accumulator of Cd and a hyper-accumulator of As, as it can lower As toxicity to a level close to the limit recommended by the World Health Organization (0.01 microg As mL(-1)). PMID:23819292

Islam, Md Shariful; Ueno, Yasuyuki; Sikder, Md Tajuddin; Kurasaki, Masaaki

2013-01-01

135

Characterization of lead resistant endophytic Bacillus sp. MN3-4 and its potential for promoting lead accumulation in metal hyperaccumulator Alnus firma.  

PubMed

The aim of this study was to isolate and characterize endophytic bacteria from the roots of the metal hyperaccumulator plant Alnus firma. A total of 14 bacterial endophytes were isolated from root samples and assayed for tolerance to heavy metals. Isolate MN3-4 exhibited maximum bioremoval of Pb and was subsequently identified as Bacillus sp. based on 16S rRNA sequences. The pH and initial metal concentration highly influenced the Pb bioremoval rate. The growth of isolate MN3-4 was moderately altered in the presence of metals. Scanning electron microscopy, energy dispersive spectroscopy, biological-transmission electron microscopy, and Fourier transform infrared spectroscopy studies revealed that isolate MN3-4 had extracellularly sequestered the Pb molecules with little intracellular accumulation. Isolate MN3-4 did not harbor pbrA and pbrT genes. Moreover, isolate MN3-4 had the capacity to produce siderophores and indoleacetic acid. A root elongation assay demonstrated an increase (46.25%) in the root elongation of inoculated Brassica napus seedlings compared to that of the control plants. Obtained results pointed out that isolate MN3-4 could potentially reduce heavy metal phytotoxicity and increase Pb accumulation in A. firma plants. PMID:22133352

Shin, Mi-Na; Shim, Jaehong; You, Youngnam; Myung, Hyun; Bang, Keuk-Soo; Cho, Min; Kamala-Kannan, Seralathan; Oh, Byung-Taek

2011-11-09

136

Micropropagation of Myriophyllum alterniflorum (Haloragaceae) for stream rehabilitation: first in vitro culture and reintroduction assays of a heavy-metal hyperaccumulator immersed macrophyte.  

PubMed

Nowadays, submersed aquatic macrophytes play a key role in stream ecology and they are often used as biomonitors of freshwater quality. So, these plants appear as natural candidates to stream rehabilitation experiments. Among them, the stream macrophyte Myriophyllum alterniflorum is used recently as biomonitor and is potentially useful for the restoration of heavy-metal contaminated localities. The best way to obtain a mass production of watermilfoil plants is micropropagation. We developed in vitro culture of M. alterniflorum and the effects of five media on the plant development were assessed. Five morphological and four physiological endpoints were examined leading to the recommendation of the Murashige and Skoog medium for ecotoxicological studies on chlorophyllous parts, and of the Gaudet medium for root cytotoxicity and phytoremediation studies. Micropropagated clones were acclimatized in a synthetic medium and in situ reintroduction was performed efficiently. This is the first report of micropropagated plants transplantation in streams. The successful establishment of watermilfoil beds even in polluted areas strongly suggested that ecological restoration using micropropagated watermilfoil is a promising biotechnology for phytoremediation and rehabilitation of degraded areas. Moreover, high bioconcentration factors evidenced that watermilfoil hyperaccumulates Cd and Cu, and could be potentially used in phytoremediation studies. PMID:23819265

Delmail, David; Labrousse, Pascal; Hourdin, Philippe; Larcher, Laure; Moesch, Christian; Botineau, Michel

2013-01-01

137

Effect of metal stress on photosynthetic pigments in the Cu-hyperaccumulating lichens Cladonia humilis and Stereocaulon japonicum growing in Cu-polluted sites in Japan.  

PubMed

To understand the ecology and physiology of metal-accumulating lichens growing in Cu-polluted sites, we investigated lichens near temple and shrine buildings with Cu roofs in Japan and found that Stereocaulon japonicum Th. Fr. and Cladonia humilis (With.) J. R. Laundon grow in Cu-polluted sites. Metal concentrations in the lichen samples collected at some of these sites were determined by inductively coupled plasma mass spectroscopy (ICP-MS). UV-vis absorption spectra of pigments extracted from the lichen samples were measured, and the pigment concentrations were estimated from the spectral data using equations from the literature. Secondary metabolites extracted from the lichen samples were analyzed by high-performance liquid chromatography (HPLC) with a photodiode array detector. We found that S. japonicum and C. humilis are Cu-hyperaccumulating lichens. Differences in pigment concentrations and their absorption spectra were observed between the Cu-polluted and control samples of the 2 lichens. However, no correlation was found between Cu and pigment concentrations. We observed a positive correlation between Al and Fe concentrations and unexpectedly found high negative correlations between Al and pigment concentrations. This suggests that Al stress reduces pigment concentrations. The concentrations of secondary metabolites in C. humilis growing in the Cu-polluted sites agreed with those in C. humilis growing in the control sites. This indicates that the metabolite concentrations are independent of Cu stress. PMID:23953993

Nakajima, Hiromitsu; Yamamoto, Yoshikazu; Yoshitani, Azusa; Itoh, Kiminori

2013-08-15

138

Fractionation of stable zinc isotopes in the field-grown zinc hyperaccumulator Noccaea caerulescens and the zinc-tolerant plant Silene vulgaris.  

PubMed

Stable Zn isotope signatures offer a potential tool for tracing Zn uptake and transfer mechanisms within plant-soil systems. Zinc isotopic compositions were determined in the Zn hyperaccumulator Noccaea caerulescens collected at a Zn-contaminated site (Viviez), a serpentine site (Vosges), and a noncontaminated site (Sainte Eulalie) in France. Meanwhile, a Zn-tolerant plant ( Silene vulgaris ) was also collected at Viviez for comparison. While ?(66)Zn was substantially differentiated among N. caerulescens from the three localities, they all exhibited an enrichment in heavy Zn isotopes of 0.40-0.72‰ from soil to root, followed by a depletion in heavy Zn from root to shoot (-0.10 to -0.50‰). The enrichment of heavy Zn in roots is ascribed to the transport systems responsible for Zn absorption into root symplast and root-to-shoot translocation, while the depletion in heavy Zn in shoots is likely to be mediated by a diffusive process and an efficient translocation driven by energy-required transporters (e.g., NcHMA4). The mass balance yielded a bulk Zn isotopic composition between plant and soil (?(66)Zn(plant-soil)) of -0.01‰ to 0.63‰ in N. caerulescens , indicative of high- and/or low-affinity transport systems operating in the three ecotypes. In S. vulgaris , however, there was no significant isotope fractionation between whole plant and rhizosphere soil and between root and shoot, suggesting that this species appears to have a particular Zn homeostasis. We confirm that quantifying stable Zn isotopes is useful for understanding Zn accumulation mechanisms in plants. PMID:22891730

Tang, Ye-Tao; Cloquet, Christophe; Sterckeman, Thibault; Echevarria, Guillaume; Carignan, Jean; Qiu, Rong-Liang; Morel, Jean-Louis

2012-08-27

139

Effect of copper stress on cup lichens Cladonia humilis and C. subconistea growing on copper-hyperaccumulating moss Scopelophila cataractae at copper-polluted sites in Japan.  

PubMed

We investigated lichen species in the habitats of the copper (Cu)-hyperaccumulating moss Scopelophila cataractae and found that the cup lichens Cladonia subconistea and C. humilis grow on this moss. We performed X-ray fluorescence and inductively coupled plasma mass (ICP-MS) analysis of lichen samples and measured the visible absorption spectra of the pigments extracted from the samples to assess the effect of Cu stress on the cup lichens. The chlorophyll a/b ratio and degradation of chlorophyll a to pheophytin a were calculated from the spectral data. X-ray fluorescence analysis indicated that Cu concentrations in cup lichens growing on S. cataractae were much higher than those in control samples growing on non-polluted soil. Moreover, Cu microanalysis showed that Cu concentrations in parts of podetia of C. subconistea growing on S. cataractae increased as the substrate (S. cataractae) was approached, whereas those of C. humilis growing on S. cataractae decreased as the substrate was approached. This reflects the difference in the route of Cu ions from the source to the podetia. Furthermore, ICP-MS analysis confirmed that C. subconistea growing on S. cataractae was heavily contaminated with Cu, indicating that this lichen is Cu tolerant. We found a significant difference between the visible absorption spectra of pigments extracted from the Cu-contaminated and control samples. Hence, the spectra could be used to determine whether a cup lichen is contaminated with Cu. Chlorophyll analysis showed that cup lichens growing on S. cataractae were affected by Cu stress. However, it also suggested that the areas of dead moss under cup lichens were a suitable substrate for the growth of the lichen. Moreover, it suggested that cup lichens had allolepathic effects on S. cataractae; it is likely that secondary metabolites produced by cup lichens inhibited moss growth. PMID:22906716

Nakajima, Hiromitsu; Fujimoto, Kenjiro; Yoshitani, Azusa; Yamamoto, Yoshikazu; Sakurai, Haruka; Itoh, Kiminori

2012-08-17

140

Expression of HMA4 cDNAs of the zinc hyperaccumulator Noccaea caerulescens from endogenous NcHMA4 promoters does not complement the zinc-deficiency phenotype of the Arabidopsis thaliana hma2hma4 double mutant  

PubMed Central

Noccaea caerulescens (Nc) exhibits a very high constitutive expression of the heavy metal transporting ATPase, HMA4, as compared to the non-hyperaccumulator Arabidopsis thaliana (At), due to copy number expansion and altered cis-regulation. We screened a BAC library for HMA4 and found that HMA4 is triplicated in the genome of a N. caerulescens accession from a former Zn mine near La Calamine (LC), Belgium. We amplified multiple HMA4 promoter sequences from three calamine N. caerulescens accessions, and expressed AtHMA4 and different NcHMA4 cDNAs under At and Nc HMA4 promoters in the A. thaliana (Col) hma2hma4 double mutant. Transgenic lines expressing HMA4 under the At promoter were always fully complemented for root-to-shoot Zn translocation and developed normally at a 2-?M Zn supply, whereas the lines expressing HMA4 under Nc promoters usually showed only slightly enhanced root to shoot Zn translocation rates in comparison with the double mutant, probably owing to ectopic expression in the roots, respectively. When expression of the Zn deficiency responsive marker gene ZIP4 was tested, the transgenic lines expressing AtHMA4 under an NcHMA4-1-LC promoter showed on average a 7-fold higher expression in the leaves, in comparison with the double hma2hma4 mutant, showing that this construct aggravated, rather than alleviated the severity of foliar Zn deficiency in the mutant, possible owing to expression in the leaf mesophyll.

Iqbal, Mazhar; Nawaz, Ismat; Hassan, Zeshan; Hakvoort, Henk W. J.; Bliek, Mattijs; Aarts, Mark G.M.; Schat, Henk

2013-01-01

141

Phytoremediation of heavy metal polluted soils and water: Progresses and perspectives*  

PubMed Central

Environmental pollution affects the quality of pedosphere, hydrosphere, atmosphere, lithosphere and biosphere. Great efforts have been made in the last two decades to reduce pollution sources and remedy the polluted soil and water resources. Phytoremediation, being more cost-effective and fewer side effects than physical and chemical approaches, has gained increasing popularity in both academic and practical circles. More than 400 plant species have been identified to have potential for soil and water remediation. Among them, Thlaspi, Brassica, Sedum alfredii H., and Arabidopsis species have been mostly studied. It is also expected that recent advances in biotechnology will play a promising role in the development of new hyperaccumulators by transferring metal hyperaccumulating genes from low biomass wild species to the higher biomass producing cultivated species in the times to come. This paper attempted to provide a brief review on recent progresses in research and practical applications of phytoremediation for soil and water resources.

Lone, Mohammad Iqbal; He, Zhen-li; Stoffella, Peter J.; Yang, Xiao-e

2008-01-01

142

Genetic and Molecular Dissection of Arsenic Hyperaccumulation  

SciTech Connect

We have constructed cDNA libraries from RNA isolated from arsenic treated gametophytes of the fern Pteris vittata. This library was made in a manner that allows each cDNA clone to be expressed in yeast. We have introduced this library into yeast cells, both wild type and arsensic sensitive mutants, and selected transformed yeast colonies with increased arsenic tolerance compared to the parental strains. From these screens we have identified putative homologs of the yeast ACR2 and ACR3 genes from Pteris vittata and, for the past year, have focused on characterizing the function of the ACR2 gene. In yeast, ACR2 is an arsenate reductase that is essential for arsenate tolerance. We refer to the Pteris vittata ACR2 gene as PvACR2. The deduced amino acid sequence of PvACR2 is highly similar to the yeast ACR2 and other related phosphatases.

Banks, Jo Ann

2005-06-01

143

COST-EFFECTIVE PHYTOEXTRACTION OF CD FROM RICE SOILS USING THLASPI CAERULESCENS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Many areas where rice is produced in Asia have become Cd+Zn contaminated by mine wastes suspended in irrigation water. Research has shown that subsistence rice farmers are more susceptible to soil Cd contamination than other exposed groups, partly because of the low bioavailability of Fe and Zn in r...

144

Extraction of pennycress (Thlaspi arvense L.) seed oil by full pressing  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pennycress is currently being developed as an oilseed crop for biofuel production. Pennycress seeds harvested from a field near Peoria, IL, provided our first opportunity to conduct an oil extraction study on a pilot scale. The goals of this study were to determine the effects of seed moisture and c...

145

Principles of classification of medicinal plants as hyperaccumulators or excluders  

Microsoft Academic Search

Strategies of plants, known as metallophytes, in response to metal excess are explored. Specific features of medicinal plants\\u000a related to metal exposition are discussed. Different parameters used for metallophyte classification are discussed. Bioaccumulation\\u000a and translocation factors are characterized. Chamomile (Matricaria recutita L.), one of the most important medicinal plants, is presented as a case history. Based on actual knowledge of

Elena Masarovi?ová; Katarína Krá?ová; Marie Kummerová

2010-01-01

146

Determination of glucosinolates in rapeseed and Thlaspi caerulescens plants by liquid chromatography–atmospheric pressure chemical ionization mass spectrometry  

Microsoft Academic Search

Liquid chromatography–atmospheric pressure chemical ionization mass spectrometry was used to identify glucosinolates in plant extracts. Optimization of the analytical conditions and the determination of the method detection limit was performed using commercial 2-propenylglucosinolate (sinigrin). Optimal values for the following parameters were determined: nebulization pressure, gas temperature, flux of drying gas, capillar voltage, corona current and fragmentor conditions. The method detection

Roser P. Tolrà; Rosa Alonso; Charlotte Poschenrieder; Damià Barceló; Juan Barceló

2000-01-01

147

Variation in HMA4 gene copy number and expression among Noccaea caerulescens populations presenting different levels of Cd tolerance and accumulation.  

PubMed

There is huge variability among populations of the hyperaccumulator Noccaea caerulescens (formerly Thlaspi caerulescens) in their capacity to tolerate and accumulate cadmium. To gain new insights into the mechanisms underlying this variability, we estimated cadmium fluxes and further characterized the N. caerulescens heavy metal ATPase 4 (NcHMA4) gene in three populations (two calamine, Saint-Félix-de-Pallières, France and Prayon, Belgium; one serpentine, Puente Basadre, Spain) presenting contrasting levels of tolerance and accumulation. Cadmium uptake and translocation varied among populations in the same way as accumulation; the population with the highest cadmium concentration in shoots (Saint Félix-de-Pallières) presented the highest capacity for uptake and translocation. We demonstrated that the four NcHMA4 copies identified in a previous study are not fixed at the species level, and that the copy truncated in the C-terminal part encodes a functional protein. NcHMA4 expression and gene copy number was lower in the serpentine population, which was the least efficient in cadmium translocation compared to the calamine populations. NcHMA4 expression was associated with the vascular tissue in all organs, with a maximum at the crown. Overall, our results indicate that differences in cadmium translocation ability of the studied populations appear to be controlled, at least partially, by NcHMA4, while the overexpression of NcHMA4 in the two calamine populations may result from convergent evolution. PMID:22581842

Craciun, Adrian R; Meyer, Claire-Lise; Chen, Jiugeng; Roosens, Nancy; De Groodt, Ruth; Hilson, Pierre; Verbruggen, Nathalie

2012-05-10

148

Natural revegetation in the vicinity of the former lead smelter in Zerjav, Slovenia.  

PubMed

The response of plant communities to pollution associated with the lead smelter in Zerjav, Slovenia, was investigated on spatial and temporal scales. In 2001, the total concentrations of contaminating metals in the soil measured at the most polluted plot were 59000 mg kg(-1) Pb, 180 mg kg(-1) Cd, and 3300 mg kg(-1) Zn. A negative correlation between the concentration of metals in the soil and plant biodiversity parameters along the gradient of pollution in 2001 was detected. Plant species lists were compiled in 2001 for plots located at different distances from the emission source and compared to that of 1981. In the period from 1981 to 2001, smelter emissions were reduced, and plant species richness increased at all examined plots. Among the successful survivals were some metal hyperaccumulators (Minuartia gerardii, Thlaspi praecox, and Biscutella laevigata). Of special interest were plants that survived the period of highest pollution. We believe that these species can be used in metal-degraded environments for natural revegetation to immobilize heavy metals. The ecosystem in the surroundings of the former smelter is presently recovering. Our results suggest that high metal concentrations in soil are a potential limiting factor for revegetation. PMID:16856725

Vidic, Tatjana; Jogan, Nejc; Drobne, Damjana; Vilhar, Barbara

2006-07-01

149

Thermal treatment of metal-enriched biomass produced from heavy metal phytoextraction.  

PubMed

Phytoextraction is an environmentally sound method for cleaning up sites that are contaminated with toxic heavy metals. However, the method has been questioned because it produces a biomass-rich secondary waste containing the extracted metals. Therefore, further treatment of this biomass is necessary. In this study, we investigated whether thermal treatment could be a feasible option for evaporatively separating metals from the plant residues. We used a laboratory scale reactor designed to simulate the volatilization behavior of heavy metals in a grate furnace. The evaporation of alkali and heavy metals from plant samples was investigated online, using a thermo-desorption spectrometer (TDS). Experiments were performed in the temperature range of 25-950 degrees C with leaves of the Cd and Zn hyperaccumulator Thlaspi caerulescens and of the high biomass plant Salix viminalis (willow), both grown on contaminated soils. Gasification (i.e., pyrolysis), which occurs under reducing conditions, was a better method than incineration under oxidizing conditions to increase volatilization and, hence subsequently recovery, of Cd and Zn from plants. It would also allow the recycling of the bottom ash as fertilizer. Thus, our investigations confirmed that incineration (or co-incineration) is a viable option for the treatment of the heavy metal-enriched plants. PMID:15926590

Keller, Catherine; Ludwig, Christian; Davoli, Frédéric; Wochele, Jörg

2005-05-01

150

Comparison of sup 14 C-GA sub 12 - aldehyde metabolism in thermo- and non-induced shoot tips of Thlaspi arvense L  

SciTech Connect

The metabolism of exogenous {sup 14}C-GA{sub 12}-aldehyde by the shoot tips of induced and noninduced field pennycress plants was compared. Both the rate of metabolism and the qualitative pattern of metabolites produced six hours after application were similar in induced and noninduced plants. The 2 major metabolites were identified by GC-MS as GA{sub 12} and an isomer of GA{sub 19}. This latter compound, however, does not appear to be native to field pennycress. Small amounts of {sup 14}C-GA{sub 12}-aldehyde were also incorporated into GA{sub 19, 20} and {sub 44}. In addition, a radioactive compound with chromatographic properties similar to GA{sub 9} was observed in plants from both treatments. These results coupled with our previous studies on kaurenoic acid metabolism indicate that the limiting step(s) in GA biosynthesis in noninduced field penny cress shoot tips lies between kaurenoic acid and GA{sub 12}-aldehyde.

Hazebroek, J.P.; Metzger, J.D. (Biosciences Research Lab., Fargo, ND (USA))

1989-04-01

151

A new process for nickel ammonium disulfate production from ash of the hyperaccumulating plant Alyssum murale.  

PubMed

The extraction of nickel (Ni) from ultramafic soils by phytomining can be achieved using Alyssum murale cultures. This study presents a new process for the valorization of Ni accumulated by this plant through the production of a Ni ammonium disulfate salt (Ni(NH(4))(2)(SO(4))(2).6H(2)O). The process comprises an initial leaching of the ashes of A. murale with a sulphuric acid solution (1.9 M H(2)SO(4), T=95 °C, t=240 min, TS=150 g ash L(-1)), producing a leachate rich in Ni (10.2 g Ni L(-1); 96% Ni solubilisation), Mg, P, K, Fe, Ca and Al. The pH of the acid leachate is increased to 5.0 with NaOH (5M), followed by an evaporation step which produced a purified solution rich in Ni (21.3 g NiL(-1)) and an iron hydroxide precipitate. The cold crystallization (T=2 °C, t=6h) of this solution by the stoichiometric addition (× 1.2) of ammonium sulfate generates a Ni ammonium disulfate salt, containing 13.2% Ni, that is potentially valuable to industry. PMID:22405560

Barbaroux, R; Plasari, E; Mercier, G; Simonnot, M O; Morel, J L; Blais, J F

2012-03-09

152

Molecular Dissection of the Cellular Mechanisms Involved in Nickel Hyperaccumulation in Plants.  

National Technical Information Service (NTIS)

Phytoremediation, the use of plants for environmental cleanup of pollutants, including toxic metals, holds the potential to allow the economic restoration of heavy metal and radionuclide contaminated sites. A number of terrestrial plants are known to natu...

1998-01-01

153

Accumulation and Remediation of Cadmium-polluted Soil by a Potential Cadmium-hyperaccumulator Chlorophytum comosum  

Microsoft Academic Search

Chlorophytum comosum was used to remediate the artificially polluted soil in a pot experiment under greenhouse conditions. The results showed that the activity of soil enzyme increased significantly in soil planted with C. comosum compared to soil not planted with C. comosum, while the concentration of cadmium in the soil reduced. The accumulation at 10 mg kg cadmium was above

Y. Wang; A. Yan; T. Wu; X. Zhang

2012-01-01

154

Predicting arsenic bioavailability to hyperaccumulator Pteris vittata in arsenic-contaminated soils.  

PubMed

Using chemical extraction to evaluate plant arsenic availability in contaminated soils is important to estimate the time frame for site cleanup during phytoremediation. It is also of great value to assess As mobility in soil and its risk in environmental contamination. In this study, four conventional chemical extraction methods (water, ammonium sulfate, ammonium phosphate, and Mehlich III) and a new root-exudate based method were used to evaluate As extractability and to correlate it with As accumulation in P. vittata growing in five As-contaminated soils under greenhouse condition. The relationship between different soil properties, and As extractability and plant As accumulation was also investigated. Arsenic extractability was 4.6%, 7.0%, 18%, 21%, and 46% for water, ammonium sulfate, organic acids, ammonium phosphate, and Mehlich III, respectively. Root exudate (organic acids) solution was suitable for assessing As bioavailability (81%) in the soils while Mehlich III (31%) overestimated the amount of As taken up by plants. Soil organic matter, P and Mg concentrations were positively correlated to plant As accumulation whereas Ca concentration was negatively correlated. Further investigation is needed on the effect of Ca and Mg on As uptake by P. vittata. Moreover, additional As contaminated soils with different properties should be tested. PMID:22908656

Gonzaga, Maria Isidória Silva; Ma, Lena Q; Pacheco, Edson Patto; dos Santos, Wallace Melo

2012-12-01

155

Matricaria chamomilla is not a hyperaccumulator, but tolerant to cadmium stress  

Microsoft Academic Search

The influence of low (3 µM) and high (60 and 120 µM) cadmium (Cd) concentrations were studied on selected aspects of metabolism in 4-week-old chamomile (Matricaria chamomilla L.) plants. After 10 days’ exposure, dry mass accumulation and nitrogen content were not significantly altered under any of the levels of Cd. However, there was a significant decline in chlorophyll and water content in the

Jozef Ková?ik; Jaroslav Tomko; Martin Ba?kor; Miroslav Rep?ák

2006-01-01

156

Engineering tolerance and hyperaccumulation of arsenic in plants by combining arsenate reductase and ?-glutamylcysteine synthetase expression  

Microsoft Academic Search

We have developed a genetics-based phytoremediation strategy for arsenic in which the oxyanion arsenate is transported aboveground, reduced to arsenite, and sequestered in thiol–peptide complexes. The Escherichia coli arsC gene encodes arsenate reductase (ArsC), which catalyzes the glutathione (GSH)-coupled electrochemical reduction of arsenate to the more toxic arsenite. Arabidopsis thaliana plants transformed with the arsC gene expressed from a light-induced

Om Parkash Dhankher; Yujing Li; Barry P. Rosen; Jin Shi; David Salt; Julie F. Senecoff; Nupur A. Sashti; Richard B. Meagher

2002-01-01

157

Zinc Hyperaccumulation in Squirrelfish (Holocentrus adscenscionis) and Its Role in Embryo Viability  

PubMed Central

Female squirrelfish (Fam. Holocentridae) can accumulate and temporarily sequester copious amounts of zinc (Zn) in their livers. There, it is initially compartmentalized before a subsequent, estrogen-triggered redistribution to the ovaries. Here we show that cellular uptake of Zn is also influenced by estrogen signaling, and that estrogen increases concentrations of the plasma Zn-binding protein vitellogenin (VTG). However, estrogen-mediated increases in VTG are not sufficient to accommodate the magnitude of hepato-ovarian Zn transfer in female squirrelfish (Holocentrus adscensionis). These findings suggest that holocentrids have acquired the ability to use hormonal cues to drive hepatic uptake and storage of Zn, signal for its physiological redistribution, and influence the capacity for systemic transport of Zn beyond the mediation of increased plasma VTG concentrations. Such specific adaptations suggest an advantage for the oocyte, which is corroborated in further studies where we determined that oocyte Zn concentrations are positively correlated with egg viability in captive-spawned squirrelfish. The novel nature of these findings underlies the importance of Zn in squirrelfish reproductive biology.

Glover, Chris N.; Capo, Tom; Walsh, Patrick J.; Hogstrand, Christer

2012-01-01

158

Antioxidative responses to arsenic in the arsenic-hyperaccumulator Chinese brake fern ( Pteris vittata L.)  

Microsoft Academic Search

This study measured antioxidative responses of Chinese brake fern (Pteris vittata L.) upon exposure to arsenic (As) of different concentrations. Chinese brake fern was grown in an artificially-contaminated soil containing 0 to 200 mg As kg?1 (Na2HAsO4) for 12 weeks in a greenhouse. Soil As concentrations at ?20 mg kg?1 enhanced plant growth, with 12–71% biomass increase compared to the

Xinde Cao; Lena Q. Ma; Cong Tu

2004-01-01

159

Accumulation and tolerance characteristics of cadmium in Chlorophytum comosum: a popular ornamental plant and potential Cd hyperaccumulator.  

PubMed

The effects on the growth, physiological indexes and the cadmium (Cd) accumulation in Chlorophytum comosum under Cd stress were examined by pot-planting. The results showed that the tolerance index (TI) of C. comosum were all above 100 in soil Cd concentration of 100 mg kg(-1). The O(2?)? production rate and electrical conductivity of C. comosum were significantly positively correlated to Cd adding-concentration while the MDA content increased and had significant differences with the control. The activities of SOD, CAT, and POD all rose significantly in lower Cd concentration and the Cd threshold of them were around 10, 50 and 20 mg kg(-1), respectively. The Cd in C. comosum root and aboveground part reached 1,522 and 865·5 mg kg(-1), respectively, in Cd concentration of soil up to 200 mg kg(-1). For the advantages of high tolerance, high accumulation, and high ornamental value, C. comosum may have tremendous application value in the treatment of Cd-contaminated soils. PMID:21625926

Wang, Youbao; Yan, Aolei; Dai, Jie; Wang, NanNan; Wu, Dan

2011-04-06

160

Accumulation and tolerance characteristics of cadmium in Chlorophytum comosum: a popular ornamental plant and potential Cd hyperaccumulator  

Microsoft Academic Search

The effects on the growth, physiological indexes and the cadmium (Cd) accumulation in Chlorophytum comosum under Cd stress were examined by pot-planting. The results showed that the tolerance index (TI) of C. comosum were all above 100 in soil Cd concentration of 100 mg kg???1. The O production rate and electrical conductivity of C. comosum were significantly positively correlated to Cd adding-concentration

Youbao Wang; Aolei Yan; Jie Dai; NanNan Wang; Dan Wu

161

NEW MOLYBDENUM-HYPERACCUMULATOR AMONG PLANT SPECIES GROWING ON MOLYBDENUM MINE A BIOCHEMICAL STUDY ON TOLERANCE MECHANISM AGAINST METAL TOXICITY  

Microsoft Academic Search

The aim of this work was to determine metal accumulation by plants growing on three molybdenum-mine zones and their tolerance strategies. The plants from tailing, extracting and non-contaminated zones were sampled with their corresponding soils. The results show that molybdenum (Mo) and copper (Cu) were at toxic levels in soils and their levels varied in 44 collected species from 21

Masoud Mashhadi Akbar Boojar; Zahra Tavakkoli

2011-01-01

162

The investigation of the possibility for using some wild and cultivated plants as hyperaccumulators of heavy metals from contaminated soil.  

PubMed

The copper production in Bor (East Serbia) during the last 100 years presents an important source of the pollution of environment. Dust, waste waters, tailing, and air pollutants influence the quality of soil, water, and air. Over 2,000 ha of fertile soil have been damaged by the flotation tailing from Bor's facilities. The goal of the present work has been to determine the content of Pb, Cu, and Fe in wild plants (17 species) naturally growing in the damaged soil and in fodder crops (nine species) planted at the same place. The content of Pb, Cu, and Fe has been analyzed in damaged soil as well. This study has also searched for native (wild) and cultivated plants which are able to grow in contaminated soil in the area of the intense industrial activity of copper production in Bor, which means that they can accumulate and tolerate heavy metals in their above-ground tissues. It has been found out that the content of all metals in contaminated soil decreases considerably at the end of the experiment. As it has been expected, all plant species could accumulate investigated metals. All tested plants, both wild-growing and cultivated plants, seem to be quite healthy on the substrate which contained extremely high concentrations of copper. PMID:22661260

Maric, Miroslava; Antonijevic, Milan; Alagic, Sladjana

2012-06-02

163

Photosystem 2 activities of hyper-accumulator Dicranopteris dichotoma Bernh from a light rare earth elements mine  

Microsoft Academic Search

The distribution of rare earth elements (REEs) in the fern Dicranopteris dichotoma Bernh plants from a light rare earth elements mine (LRM) and a non-mining (NM) area in Longnan county of Jiangxi province,\\u000a China were investigated by means of inductively coupled plasma-mass spectrometry, transmission electron microscopy, and energy-dispersive\\u000a X-ray microanalysis. The photosynthetic characteristics of D. dichotoma were studied by chlorophyll

L. F. Wang; H. B. Ji; K. Z. Bai; L. B. Li; T. Y. Kuang

2006-01-01

164

Effect of fertilizers on Cd uptake of Amaranthus hypochondriacus, a high biomass, fast growing and easily cultivated potential Cd hyperaccumulator.  

PubMed

In a greenhouse pot experiment, we assessed the phytoextraction potential for Cd of three amaranth cultivars (Amaranthus hypochondriacus L. Cvs. K112, R104, and K472) and the effect of application of N, NP, and NPK fertilizer on Cd uptake of the three cultivars from soil contaminated with 5 mg kg(-1) Cd. All three amaranth cultivars had high levels of Cd concentration in their tissues, which ranged from 95.1 to 179.1 mg kg(-1) in leaves, 58.9 to 95.4 mg kg(-1) in stems, and 62.4 to 107.2 mg kg(-1) in roots, resulting in average bioaccumulation factors ranging from 17.7 to 29.7. Application of N, NP, or NPK fertilizers usually increased Cd content in leaves but decreased Cd content in stem and root. Fertilizers of N or NP combined did not substantially increase dry biomass of the 3 cultivars, leading to a limited increment of Cd accumulation. NPK fertilizer greatly increased dry biomass, by a factor of 2.7-3.8, resulting in a large increment of Cd accumulation. Amaranth cultivars (K112, R104, and K472) have great potential in phytoextraction of Cd contaminated soil. They have the merits of high Cd content in tissues, high biomass, easy cultivation and little effect on Cd uptake by fertilization. PMID:22567702

Li, Ning Yu; Fu, Qing Lin; Zhuang, Ping; Guo, Bing; Zou, Bi; Li, Zhi An

2012-02-01

165

Refeeding-induced brown adipose tissue glycogen hyper-accumulation in mice is mediated by insulin and catecholamines.  

PubMed

Brown adipose tissue (BAT) generates heat during adaptive thermogenesis through a combination of oxidative metabolism and uncoupling protein 1-mediated electron transport chain uncoupling, using both free-fatty acids and glucose as substrate. Previous rat-based work in 1942 showed that prolonged partial fasting followed by refeeding led to a dramatic, transient increase in glycogen stores in multiple fat depots. In the present study, the protocol was replicated in male CD1 mice, resulting in a 2000-fold increase in interscapular BAT (IBAT) glycogen levels within 4-12 hours (hr) of refeeding, with IBAT glycogen stores reaching levels comparable to fed liver glycogen. Lesser effects occurred in white adipose tissues (WAT). Over the next 36 hr, glycogen levels dissipated and histological analysis revealed an over-accumulation of lipid droplets, suggesting a potential metabolic connection between glycogenolysis and lipid synthesis. 24 hr of total starvation followed by refeeding induced a robust and consistent glycogen over-accumulation similar in magnitude and time course to the prolonged partial fast. Experimentation demonstrated that hyperglycemia was not sufficient to drive glycogen accumulation in IBAT, but that elevated circulating insulin was sufficient. Additionally, pharmacological inhibition of catecholamine production reduced refeeding-induced IBAT glycogen storage, providing evidence of a contribution from the central nervous system. These findings highlight IBAT as a tissue that integrates both canonically-anabolic and catabolic stimulation for the promotion of glycogen storage during recovery from caloric deficit. The preservation of this robust response through many generations of animals not subjected to food deprivation suggests that the over-accumulation phenomenon plays a critical role in IBAT physiology. PMID:23861810

Carmean, Christopher M; Bobe, Alexandria M; Yu, Justin C; Volden, Paul A; Brady, Matthew J

2013-07-04

166

Lead Uptake and Effects on Seed Germination and Plant Growth in a Pb Hyperaccumulator Brassica pekinensis Rupr  

Microsoft Academic Search

Heavy metal contamination of soil, water and air has caused serious environmental hazard in the biosphere due to rapid industrialization and urbanization. Lead is probably one of the most frequently encountered heavy metals in polluted environment. The primary sources of this metal include mining and smelting of metalliferous ores, burning of leaded gasoline, disposal of municipal sewage and industrial wastes

Z.-T. Xiong

1998-01-01

167

Effect of citric acid on phytoextraction and antioxidative defense in Solanum nigrum L. as a hyperaccumulator under Cd and Pb combined pollution  

Microsoft Academic Search

The impact of citric acid on the ability of Solanum nigrum L. to accumulate heavy metals and on its antioxidant enzyme activity were investigated to further elucidate the effect of\\u000a chelation on the heavy metal uptake and antioxidative defense in plants under conditions of heavy metal pollution. In the\\u000a presence of multiple metal contaminants (Cd and Pb), citric acid treatment

Yang GaoChiyuan; Chiyuan Miao; Jun Xia; Chunyan Luo; Liang Mao; Pei Zhou; Wanjun Shi

168

Identification and validation of heavy metal and radionuclide hyperaccumulating terrestrial plant species. Quarterly progress report, July 1, 1996--September 30, 1996  

SciTech Connect

Potential for phytoremediation of an aged radiocesium-contaminated soil from Brookhaven National Laboratory was investigated in three phases: (1) hydroponic screening for plant species capable of accumulating elevated levels of cesium in shoots, (2) amending contaminated soil to enhance {sup 137}Cs bioavailability, and (3) phytoextracting radiocesium with plant roots and its removal in harvested shoots. The bioaccumulation ratio of Cs in shoots of hydroponically grown plants ranged between 38 and 165. From solution, dicot species accumulated 2- to 4-fold more cesium in shoots than grasses. The effect of several chemical compounds on {sup 137}Cs desorption from the contaminated soil was investigated. Ammonium salts were the most effective at desorbing Cs from contaminated soil, but only 25% of radiocesium could be desorbed. Although release of radiocesium from the soil was concentration-dependent, this effect appeared to level off above 0.2 M ammonium in solution. In a pot study, from the soil contaminated with 400 pCi g{sup -1} soil, the greatest amount of {sup 137}Cs, 140 pCi, was removed in shoots of cabbage (Brassica oleracea var. capitata). {sup 137}Cs accumulation in shoots was significantly increased by the addition of 40 NH{sub 4}NO{sub 3} kg{sup -1} soil. Increasing NH{sub 4}NO{sub 3} application from 40 to 80 mmoles kg{sup -1} soil did not further increase radiocesium phytoextraction. The ability to accumulate radiocesium from soil in shoots was significantly different among species tested. This ability increased in order: reed Canary grass (Phalaris arundinacea) < Indian mustard (Brassica juncea) < tepary bean (Phaseolus acutifolius) < cabbage.

Kochian, L. [Cornell Univ., Ithaca, NY (United States)

1997-05-01

169

Off-line separation and determination of rare earth elements associated with chloroplast pigments of hyperaccumulator Dicranopteris dichotoma by normal-phase liquid chromatography and ICP–MS  

Microsoft Academic Search

An off-line normal-phase liquid chromatography–ICP–MS method has been used for separation and determination of the rare earth elements (REE) associated with chloroplast pigments of Dicranopteris dichotoma. The stability of REE-bound pigments was tested, and almost no destruction of REE-bound pigments occurred during the so-called normal-phase liquid chromatography. The accumulated free REE ions on the microcrystalline cellulose column were cleaned by

Z. G. Wei; F. S. Hong; M. Yin; H. X. Li; F. Hu; G. W. Zhao; J. W. C. Wong

2004-01-01

170

The current status of the elemental defense hypothesis in relation to pathogens  

PubMed Central

Metal hyperaccumulating plants are able to accumulate exceptionally high concentrations of metals, such as zinc, nickel, or cadmium, in their aerial tissues. These metals reach concentrations that would be toxic to most other plant species. This trait has evolved multiple times independently in the plant kingdom. Recent studies have provided new insight into the ecological and evolutionary significance of this trait, by showing that some metal hyperaccumulating plants can use high concentrations of accumulated metals to defend themselves against attack by pathogenic microorganisms and herbivores. Here, we review the evidence that metal hyperaccumulation acts as a defensive trait in plants, with particular emphasis on plant–pathogen interactions. We discuss the mechanisms by which defense against pathogens might have driven the evolution of metal hyperaccumulation, including the interaction of this trait with other forms of defense. In particular, we consider how physiological adaptations and fitness costs associated with metal hyperaccumulation could have resulted in trade-offs between metal hyperaccumulation and other defenses. Drawing on current understanding of the population ecology of metal hyperaccumulator plants, we consider the conditions that might have been necessary for metal hyperaccumulation to be selected as a defensive trait, and discuss the likelihood that these were fulfilled. Based on these conditions, we propose a possible scenario for the evolution of metal hyperaccumulation, in which selective pressure for resistance to pathogens or herbivores, combined with gene flow from non-metallicolous populations, increases the likelihood that the metal hyperaccumulating trait becomes established in plant populations.

Horger, Anja C.; Fones, Helen N.; Preston, Gail M.

2013-01-01

171

A newly found cadmium accumulator— Taraxacum mongolicum  

Microsoft Academic Search

Identification of hyperaccumulator and accumulator is still key step of phytoextracting-contaminated soils by heavy metals. In a former published experiment, Taraxacum mongolicum showed basic characteristics of hyperaccumulators. In order to confirm if this plant was a Cd-hyperaccumulator, concentration gradient experiment and sample-analyzing experiments were designed and performed. The results showed that Cd enrichment factor and Cd transformation factor of T.

Shuhe Wei; Qixing Zhou; Shiny Mathews

2008-01-01

172

Trends in literature on new oilseed crops and related species: Seeking evidence of increasing or waning interest  

Technology Transfer Automated Retrieval System (TEKTRAN)

Bibliographic records on eight new crop species Camelina, Crambe, Cuphea, Physaria, Limnanthes, Stokesia, Thlaspi, and Vernonia from Agricola, CAB Abstracts, Scopus, and Web of Science were analyzed for historical and recent trends in the areas of research, author distribution, and quantity and impa...

173

Seed oil development of pennycress under field conditions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pennycress (Thlaspi sp) has been targeted as a potential oilseed for the biofuels industry. Its seeds contain ~36% oil, where erucic acid is the major fatty acid presented with 38.1%. Additionally, the physical proprieties of the methyl esters are in the range to satisfy the needs of the biodiesel m...

174

Amaranthus Tricolor Has the Potential for Phytoremediation of Cadmium?Contaminated Soils  

Microsoft Academic Search

Phytoremediation is a developing technology that uses plants to clean up pollutants in soils. To adopt this technology to cadmium (Cd)–contaminated soils efficiently, a Cd hyperaccumulator with fast growth rate and large biomass is required. In the present study, we selected Caryophyllales as a potential clade that might include Cd hyperaccumulators because this clade had a high mean concentration of

Toshihiro Watanabe; Yasutoshi Murata; Mitsuru Osaki

2009-01-01

175

Phytoextraction of metals and metalloids from contaminated soils  

Microsoft Academic Search

The removal of inorganic contaminants by plants is termed phytoextraction. Recent studies have looked at the feasibility of phytoextraction, and demonstrate that both good biomass yields and metal hyperaccumulation are required to make the process efficient. Adding chelating agents to soil to increase the bioavailability of contaminants can sometimes induce hyperaccumulation in normal plants, but may produce undesirable environmental risks.

Steve P McGrath; Fang-Jie Zhao

2003-01-01

176

Poplar maintains zinc homeostasis with heavy metal genes HMA4 and PCS1  

Technology Transfer Automated Retrieval System (TEKTRAN)

This project has identified two large gene families, HMA and ZIP, in poplar that have been greatly expanded by the latest Salicoid genome duplication in poplar. In other species, these two families have been shown to be central in both hyperaccumulators and non-hyperaccumulators In poplar, many of t...

177

Bacterial Inoculants Affecting Nickel Uptake by Alyssum murale From Low, Moderate and High Ni Soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Metal hyperaccumulator plants like Alyssum murale have a remarkable ability to hyperaccumulate Ni from soils containing mostly insoluble Ni. We have shown some rhizobacteria increase the phytoavailability of Ni in soils, thus enhancing Ni accumulation by A. murale. Nine bacterial strains, originally...

178

MECHANISMS OF NICKEL UPTAKE AND HYPERACCUMULATON BY THE PLANTS AND IMPLICATION TO PHYTOREMEDIATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

More than 300 plant species are known to be Ni hyperaccumulators, and these are capable of accumulating a very high concentrations of Ni without any adverse effects. Progress is being made to understand the physiological, biochemical, molecular and genetic basis of Ni tolerance and hyperaccumulation...

179

Antioxidative response of metal-accumulator and non-accumulator plants under cadmium stress  

Microsoft Academic Search

The present study aims to elucidate the role of antioxidative enzyme in the adaptive responses of metal-accumulators (Thlaspi caerulescens and Brassica juncea) and non-accumulator plant (Nicotiana tabacum) to Cadmium stress. When seedlings of plants were grown in hydroponic condition for a period of 4 days in the presence of\\u000a 200 or 400 ?M CdCl2, photosynthetic rate, transpiration rate and stomatal conductance in

Zi Wang; Yuxiu Zhang; Zhibo Huang; Lin Huang

2008-01-01

180

Roles of Organic Acids and Nitrate in the Long-Distance Transport of Cobalt in Xylem Saps of Alyssum murale and Trifolium subterraneum  

Microsoft Academic Search

Roles of organic acids and nitrate in the long-distance transport of cobalt (Co) in xylem saps of hyperaccumulator Alyssum murale and non-hyperaccumulator Trifolium subterraneum were studied under hydroponic conditions. Organic acids (oxalic, malic, malonic, citric, and fumaric) and nitrate in xylem\\u000a sap samples were separated and determined simultaneously by reversed-phase high performance liquid chromatography after solid-phase\\u000a extraction with nanosized hydroxyapatite.

Wei Wei; Yu Wang; Zheng-Gui Wei; Hai-Yan Zhao; Hui-Xin Li; Feng Hu

2009-01-01

181

Chelate-Enhanced Phytoremediation of Soils Polluted with Heavy Metals  

Microsoft Academic Search

In general, hyperaccumulators are low biomass, slow-growing plants. High biomass non-hyperaccumulator plants by themselves are not a valid alternative for phytoextraction as they also have many limitations, such as small root uptake and little root-to-shoot translocation. In this context, chemically-induced phytoextraction (based on the fact that the application of certain chemicals, mostly chelating agents, to the soil significantly enhances metal

I. Alkorta; J. Hernández-Allica; J. M. Becerril; I. Amezaga; I. Albizu; M. Onaindia; C. Garbisu

2004-01-01

182

Metallophytes—a view from the rhizosphere  

Microsoft Academic Search

Some plants hyperaccumulate metals or metalloids to levels several orders of magnitude higher than other species. This intriguing\\u000a phenomenon has received considerable attention in the past decade. While research has mostly focused on the above-ground organs,\\u000a roots are the sole access point to below-ground trace elements and as such they play a vital role in hyperaccumulation. Here\\u000a we highlight the

Élan R. Alford; Elizabeth A. H. Pilon-Smits; Mark W. Paschke

2010-01-01

183

Plant defense using toxic inorganic ions: conceptual models of the defensive enhancement and joint effects hypotheses.  

PubMed

The concept of plant defense using toxic mineral elements originated as an explanation for extremely elevated concentrations of some elements (termed hyperaccumulation) in some plant tissues. The Defensive Enhancement Hypothesis suggests that hyperaccumulation evolved because, after an initial defensive benefit accrued from a relatively low initial concentration, increased concentration of an element provided increased plant fitness and drove evolution of higher element concentrations until hyperaccumulation was achieved. The Joint Effects Hypothesis postulates that additive or synergistic effects between element-based defenses, or between toxic element and organic chemical defenses, may have contributed to the evolution of hyperaccumulation. By lessening the concentration of an element necessary to provide an initial defensive benefit to a plant, joint effects could decrease the level of an element that provides an initial defensive benefit, allowing additive or synergistic defensive enhancement to take effect. Recent experimental tests have demonstrated defense at relatively low element concentrations, and tests of metal/metal and metal/organic compound combinations have shown joint effects. These hypotheses suggest how hyperaccumulator plants may have evolved in response to plant-herbivore interactions, and suggest that toxic element levels below those used to define hyperaccumulation may be ecologically effective. PMID:22921002

Boyd, Robert S

2012-07-04

184

The use of the model species Arabidopsis halleri towards phytoextraction of cadmium polluted soils.  

PubMed

Phytoremediation consists in treating environmental pollutions through the use of plants and their associated microbes. Phytoremediation can be used for pollutant stabilization, extraction, degradation or volatilization. Cadmium is one of the most toxic trace metallic elements for living organisms and its accumulation in the environment is recognized as a worldwide concern. Plants suitable for efficient pollutant extraction from the soil should combine different characteristics like fast growth, high biomass, high tolerance and high accumulation capacities in harvestable parts. A rare class of plants called hyperaccumulators combines extremely high tolerance degrees and foliar accumulation of trace elements. With regard to cadmium, none of the Cd hyperaccumulators identified has met the criteria for efficient phytoextraction so far. By virtue of genetic engineering it is possible to transfer genes involved in Cd tolerance or accumulation in high biomass plants. Nevertheless, the genetic determinants of Cd hyperaccumulation are far from being understood. It is thus indispensable to acquire more knowledge about these processes. Among Cd hyperaccumulators, Arabidopsis halleri (some populations can hyperaccumulate Cd) is considered as a model species for the study of metal homeostasis and detoxification. This review will summarize our knowledge about Cd tolerance and accumulation acquired in A. halleri and how this knowledge may be used in phytoextraction. PMID:22850245

Claire-Lise, Meyer; Nathalie, Verbruggen

2012-07-28

185

Replication and encapsidation of the viroid-like satellite RNA of lucerne transient streak virus are supported in divergent hosts by cocksfoot mottle virus and turnip rosette virus.  

PubMed

Cocksfoot mottle sobemovirus supports replication and encapsidation of the viroid-like satellite RNA (sat-RNA) of lucerne transient streak virus (LTSV) in two monocotyledonous species, Triticum aestivum and Dactylis glomerata. Additionally, LTSV sat-RNA replicates effectively in the presence of turnip rosette sobemovirus in Brassica rapa, Raphanus raphanistrum and Sinapsis arvensis, but not in Thlaspi arvense or Nicotiana bigelovii, indicating that host species markedly influence this interaction. Previous reports of the association between LTSV sat-RNA and helper sobemoviruses were limited to dicotyledonous hosts. Our results demonstrate that the biological interaction between these two entities spans divergent dicotyledonous and monocotyledonous species. PMID:7682254

Sehgal, O P; Sinha, R C; Gellatly, D L; Ivanov, I; AbouHaidar, M G

1993-04-01

186

Isolation and characterization of metal resistant-tolerant rhizosphere bacteria from the serpentine soils in Turkey  

Microsoft Academic Search

Despite the number of studies describing metal hyper-accumulating plants and their associated bacteria in various regions\\u000a and countries, there is no information on rhizosphere microbial potential of the Turkish serpentine soils. This study aimed\\u000a to explore the rhizosphere microbial diversity of Ni-resistant, hyper-accumulating plants grown on Ni-rich soils and their\\u000a metal tolerance–resistance characteristics. One hundred ninety-one locations were visited to

O?uz Can Turgay; Arzu Görmez; Serdar Bilen

187

Engineering Plant-Microbe Symbiosis for Rhizoremediation of Heavy Metals  

Microsoft Academic Search

The use of plants for rehabilitation of heavy-metal-contaminated environments is an emerging area of interest because it provides an ecologically sound and safe method for restoration and remediation. Although a number of plant species are capable of hyperaccumulation of heavy metals, the technology is not applicable for remediating sites with multiple contaminants. A clever solution is to combine the advantages

Cindy H. Wu; Thomas K. Wood; Ashok Mulchandani; Wilfred Chen

2006-01-01

188

DEVELOPMENT OF A NEW TECHNOLOGY FOR PHYTOEXTRACTION OF NICKEL - COMMERCIAL CONSIDERATIONS  

Technology Transfer Automated Retrieval System (TEKTRAN)

We have made important progress in developing a commercial technology using hyperaccumulator plant species to phytoextract nickel (Ni) from contaminated and/or Ni-rich soils. Development of such a technology required identifying or creating an ideal phytoextraction plant, optimizing soil and crop m...

189

Promoted dissipation of phenanthrene and pyrene in soils by amaranth ( Amaranthus tricolor L.)  

Microsoft Academic Search

A study was conducted to investigate the performance of amaranth, a known hyperaccumulator of cesium, on the promotion of the dissipation of soil phenanthrene and pyrene, which are PAHs (polycyclic aromatic hydrocarbons). Amaranthus tricolor L. ‘een choi’ was the cultivar used. The presence of Amaranthus tricolor L. evidently enhanced the dissipation of these PAHs in soils with initial phenanthrene concentrations

Wanting Ling; Yanzheng Gao

2004-01-01

190

Selenium Accumulation in Flowers and its Effects on Pollination  

Technology Transfer Automated Retrieval System (TEKTRAN)

Selenium, both an essential micronutrient and a potential toxin, is hyperaccumulated by some plants up to 1% of dry weight. The functional significance of this rare phenomenon may be an elemental defense against herbivores and pathogens. In this first of its kind study, we investigate Se distributio...

191

Phytoremediation of metals, metalloids, and radionuclides  

Microsoft Academic Search

Phytoremediation is a developing technology that can potentially address the problems of contaminated agricultural land or more intensely polluted areas affected by urban or industrial activities. Three main strategies currently exist to phytoextract inorganic substances from soils using plants:(1) use of natural hyperaccumulators; (2) enhancement of element uptake of high biomass species by chemical additions to soil and plants; and

S. P. McGrath; J. Zhao; E. Lombi

2002-01-01

192

The Potential of Thelypteris palustris and Asparagus sprengeri in Phytoremediation of Arsenic Contamination  

Microsoft Academic Search

The potential of two plants, Thelypteris palustris (marsh fern) and Asparagus sprengeri (asparagus fern), for phytoremediation of arsenic contamination was evaluated. The plants were chosen for this study because of the discovery of the arsenic hyperaccumulating fern, Pteris vittata (Ma et al., 2001) and previous research indicating asparagus fern's ability to tolerate >1200 ppm soil arsenic. Objectives were (1) to

LaShunda L. Anderson; Maud Walsh; Amitava Roy; Christopher M. Bianchetti; Gregory Merchan

2010-01-01

193

Physiological Functions of Nitric Oxide in Sedum Alfredii Hance under Complex Heavy Metals Stress  

Microsoft Academic Search

Heavy metals contamination is a major environmental issue, and phytoremediation is a promising, environmentally friendly alternative to conventional cleanup techniques for heavy metal contaminated sites. This paper is intended to explore the physiological functions of nitric oxide (NO) in the signaling pathways as well as defense responses in Sedum Alfredii Hance, a new zinc (Zn) promising hyperaccumulating plant species for

Xiao-ling Zhang; Youqiong Cai; Qiao Yang; Wuzhong Ni; Yunhua Hui; Huijuan Yu

2009-01-01

194

Arsenic and heavy metal accumulation by Athyrium yokoscense from contaminated soils  

Microsoft Academic Search

Athyrium yokoscense, a type of fern that grows vigorously in mining areas in Japan, is well known as a Cd hyperaccumulator as well as a Cu, Pb and Zn tolerant plant. However, no information is available on As accumulation of A. yokoscense, although it often grows on soils containing high levels of both heavy metals and As. In this study, young

Tran Khanh Van; Yumei Kang; Takahiro Fukui; Katsutoshi Sakurai; K?z? Iwasaki; Yoshio Aikawa; Nguyen Minh Phuong

2006-01-01

195

Phytoaccumulation of trace elements by wetland plants: 3. Uptake and accumulation of ten trace elements by twelve plant species  

Microsoft Academic Search

Interest is increasing in using wetland plants in constructed wetlands to remove toxic elements from polluted wastewater. To identify those wetland plants that hyperaccumulate trace elements, 12 plant species were tested for their efficiency to bioconcentrate 10 potentially toxic trace elements including As, b, Cd, Cr, Cu, Pb, Mn, Hg, Ni, and Se. Individual plants were grown under carefully controlled

Jin-Hong Qian; Adel Zayed; Yong-Liang Zhu; Mei Yu; Norman Terry

1999-01-01

196

The effect of EDTA and citric acid on phytoremediation of Cd, Cr, and Ni from soil using Helianthus annuus  

Microsoft Academic Search

The possibility to clean heavy metal contaminated soils with hyperaccumulator plants has shown great potential. One of the most recently studied species used in phytoremediation applications are sunflowers. In this study, two cultivars of Helianthus annuus were used in conjunction with ethylene diamine tetracetic acid (EDTA) and citric acid (CA) as chelators. Two different concentrations of the chelators were studied

Cafer Turgut; M. Katie Pepe; Teresa J. Cutright

2004-01-01

197

Chelator-buffered nutrient solution is ineffective in extracting Ni from seeds of Alyssum  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hyperaccumulator species of the genera Alyssum can accumulate 100 times more Ni than normal crops and are therefore used for phytomining and phytoextraction of nickel contaminated soils. Basic studies on the physiology and metal uptake mechanisms of these plants are needed to increase efficiency and...

198

NiO(s) (Bunsenite) is not Available to Alyssum species  

Technology Transfer Automated Retrieval System (TEKTRAN)

AIMS: To determine if the Ni-hyperaccumulator Alyssum corsicum can absorb Ni from the kinetically inert crystalline mineral NiO(s) (bunsenite). METHODS: A. corsicum and A. montanum plants were grown for 30 days in a serpentine Hoagland solution. NiO was provided at 0 or 0.1 g L-1 (1.34 mmol L-1) ...

199

Making Phytoremediation Work Better: Maximizing a Plant’s Growth Potential in the Midst of Adversity  

Microsoft Academic Search

While a number of different plants can either breakdown a variety of organic contaminants or hyperaccumulate metals from the environment, even the most efficient of those plants is typically inhibited by the presence of the toxicant(s). The plant stress that is induced by the presence of various environmental toxicants typically limits a plant's growth and ultimately its ability to phytoremediate

Bernard R. Glick; Jennifer C. Stearns

2011-01-01

200

Making phytoremediation work better: Maximizing a plant's growth potential in the midst of adversity  

Microsoft Academic Search

While a number of different plants can either breakdown a variety of organic contaminants or hyperaccumulate metals from the environment, even the most efficient of those plants is typically inhibited by the presence of the toxicant(s). The plant stress that is induced by the presence of various environmental toxicants typically limits a plant's growth and ultimately its ability to phytoremediate

Bernard R. Glick; Jennifer C. Stearns

2011-01-01

201

EFFECTIVENESS OF APPLYING ARSENATE` REDUCING BACTERIA TO ENHANCE ARSENIC REMOVAL FROM POLLUTED SOILS BY PTERIS VITTATA L  

Microsoft Academic Search

Arsenic is a common contaminant in soils and water. It is well-established that the fern Pteris vittata L. is an As hyperaccumulator and therefore has potential to phyroremediate As-polluted soils. Also, it is accepted that rhizosphere microflora play an enhancing role in plant uptake of metallic elements from soils. Studies showed that hydroponiclly grown P. Vittata accumulated arsenite more than

Q. Yang; S. Tu; G. Wang; X. Liao; X. Yan

2011-01-01

202

Effectiveness of Applying Arsenate Reducing Bacteria to Enhance Arsenic Removal From Polluted Soils by Pteris Vittata L  

Microsoft Academic Search

Arsenic is a common contaminant in soils and water. It is well established that the fern Pteris vittata L. is an As hyperaccumulator and therefore has potential to phyroremediate As-polluted soils. Also, it is accepted that rhizosphere microflora play an enhancing role in plant uptake of metallic elements from soils. Studies showed that hydroponiclly grown P. Vittata accumulated arsenite more

Q. Yang; S. Tu; G. Wang; X. Liao; X. Yan

2012-01-01

203

Harvesting a crop of gold in plants  

Microsoft Academic Search

The possibility of turning base metals into gold has intrigued many scientists since the early alchemists, and the discovery of significant gold uptake by plants has long been a `philosopher's stone'. But background levels of gold in plants are usually very low, rarely exceeding 10 ng per g dry tissue (10 p.p.b.). Hyperaccumulator plants, however, have 100 times the elemental

Christopher W. N. Anderson; Robert R. Brooks; Robert B. Stewart; Robyn Simcock

1998-01-01

204

Mechanisms of cadmium detoxification in cattail ( Typha angustifolia L.)  

Microsoft Academic Search

Cadmium (Cd) is a widespread heavy metal pollutant and environmental and human health hazard, which may be partially resolved using green and cost-effective phytoremediation techniques. However, the efficiency of phytoremediation is often limited by the small biomass of Cd-hyperaccumulator plants. Although cattail (Typha angustifolia L.) is tolerant of heavy metals and has a high biomass, there is little information available

Weifeng Xu; Weiming Shi; Feng Yan; Biao Zhang; Jiansheng Liang

2011-01-01

205

The Engineered Phytoremediation of Ionic and Methylmercury Pollution  

SciTech Connect

Our current specific objectives are to use transgenic plants to control the chemical species, electrochemical state, and above ground binding of mercury to (a) prevent methylmercury from entering the food-chain, (b) remove mercury from polluted sites, and (c) hyperaccumulate mercury in above ground tissues for later harvest.

Richard Meagher; Sarah Marshburn; Andrew Heaton; Anne Marie Zimer; Raoufa Rahman

2003-06-24

206

Chemical Mutagenesis—A Promising Technique to Increase Metal Concentration and Extraction in Sunflowers  

Microsoft Academic Search

Since most of the metal-hyperaccumulating wild plants only produce very low biomass and many high-yielding crops accumulate only moderate amounts of metals, the current research is mainly focused on overcoming these limitations and the optimization of metal phytoextraction. The main goal of the present study was the improvement of metal concentration and extraction properties of Helianthus annuus L by chemical

Erika Nehnevajova; Rolf Herzig; Guido Federer; Karl-Hans Erismann; Jean-Paul Schwitzguébel

2007-01-01

207

USE OF NOVEL SYNCHROTRON-BASED TECHNIQUES TO EXPLORE THE CONNECTION BETWEEN METAL SPECIATION IN SOILS AND PLANTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

We investigated the speciation of Ni in smelter contaminated soils in order to discern what effect Ni speciation has on the availability and compartmentalization of Ni in the hyperaccumulator Alyssum murale. Using a combination of techniques including SEM, micro-XAFS and SXRF it was found that the ...

208

DEGRADATION OF ALYSSUM BIOMASS IN SOIL  

Technology Transfer Automated Retrieval System (TEKTRAN)

The reasons for Ni hyperaccumulation remain unproven; however, elemental allelopathy has been suggested as a possible reason for this unusual trait. It has been suggested that continual transport of Ni from soil to leaves, then shedding of leaves to fall on the soil surface, may create a Ni toxic zo...

209

A Comparison of Sulfate and Selenium Accumulation in Relation to the Expression of Sulfate Transporter Genes in Astragalus Species1[OA  

PubMed Central

Sulfate and selenate uptake were investigated in both selenium (Se) hyperaccumulators (Astragalus racemosus and Astragalus bisulcatus) and closely related nonaccumulator species (Astragalus glycyphyllos and Astragalus drummondii). Sulfur (S) starvation increased Se accumulation, whereas increased selenate supply increased sulfate accumulation in both root and shoot tissues. cDNAs for homologs of groups 1 to 4 sulfate transporters were cloned from these Astragalus species to investigate patterns of expression and interactions with sulfate and selenate uptake. In contrast to all other previously analyzed plant species, abundant gene expression of putative sulfate transporters was observed for both Se-hyperaccumulating and nonaccumulating Astragalus, regardless of S and Se status. Furthermore, quantitative analysis of expression indicated a transcript level in Se-hyperaccumulating Astragalus comparable with other plant species under S deprivation. The high expression of sulfate transporters in certain Astragalus species may lead to enhanced Se uptake and translocation ability and therefore may contribute to the Se hyperaccumulation trait; however, it is not sufficient to explain S/Se discriminatory mechanisms.

Cabannes, Emmanuelle; Buchner, Peter; Broadley, Martin R.; Hawkesford, Malcolm J.

2011-01-01

210

Characteristics of heavy metal uptake by plant species with potential for phytoremediation and phytomining  

Microsoft Academic Search

Genetically transformed hairy root cultures were established for a range of plant species and applied in studies of growth and accumulation of heavy metals. Experiments were conducted using liquid nutrient medium containing elevated concentrations of Ni, Cd or Cu. Hairy roots of three hyperaccumulator species were tested for Ni uptake, of these, Alyssum bertolonii accumulated the highest Ni contents in

T. V. Nedelkoska; P. M. Doran

2000-01-01

211

Phytoremediative urban design: Transforming a derelict and polluted harbour area into a green and productive neighbourhood.  

PubMed

Many urban areas are polluted by industrial activities and waste disposal in landfills. Since conventional soil remediation techniques are costly and unsustainable, phytoremediation might offer an alternative. In this article, we explore how phytoremediation can be integrated into the transformation of urban post-industrial areas, while improving public space. Buiksloterham, a polluted and deprived industrial area in Amsterdam, serves as case study. Buiksloterham is polluted with heavy metals, with Zinc (Zn) concentrations being the highest. A regression-model for Alpine Pennycress (Thlaspi caerulescens) is used to estimate the time needed to remediate the site. This reveals a conflict in time between remediation and urban development. A research by design experiment shows how to overcome this conflict by dealing with polluted soil innovatively while emphasizing spatial and aesthetic qualities of the phytoremediation plant species. The resulting landscape framework integrates phytoremediation with biomass production and gives new ecological, economic and social value to Buiksloterham. PMID:23452757

Wilschut, M; Theuws, P A W; Duchhart, I

2013-02-26

212

Fanweed toxicosis in cattle: case history, analytical method, suggested treatment, and fanweed detoxification.  

PubMed

Two hundred and twenty head of pregnant cows were fed virtually 100% fanweed (Thlaspi arvense) in November 1984. One hundred became distressed and colicy within 4 hr of feeding. Eight died over the next 5 days despite removal of the feed and symptomatic treatment. Necropsy revealed massive submucosal edema of the wall of the forestomachs, particularly the rumen. Four abortions occurred. The feed was analyzed and was found to liberate 250 mg/100g of AITC. Possible methods of treatment were devised in case the problem should recur. Fanweed contains sinigrin and the enzyme myrosin. When the plant is crushed and moistened, allylisothiocyanate (AITC) is formed along with glucose and potassium acid sulfate. Application of Le Chatelier's principle led to an investigation of the effect of pH on in vitro generation of AITC. Methods of destroying AITC were also examined, and detoxification studies were undertaken on fanweed. PMID:3576950

Smith, R A; Crowe, S P

1987-04-01

213

Cloning and expression of Brassica napus beta-carbonic anhydrase cDNA.  

PubMed

A new full-length beta-carbonic anhydrase cDNA was obtained from Brassica napus by homologous cloning. The cDNA has an open-reading frame of 996 nucleotides, encoding 331 amino acids with a calculated molecular weight of 35,692 Da and an estimated pI value of 5.459. The deduced amino acid sequence of beta-carbonic anhydrase from Brassica napus shared significant identity with beta-carbonic anhydrases from Brassica carinata, Arabidopsis thaliana, and Thlaspi caerulescens (97.9%, 94%, and 93.5% identity, respectively). This cDNA was expressed in Escherichia coli BL21 (DE3) using the expression vector pET-32a(+). The expression band corresponded to the calculated mass plus the N-terminal fusion protein derived from the vector. PMID:20158161

Deng, Qiu-Hong; Li, Mao-Teng; Yu, Long-Jiang

214

Evaluation of three ornamental plants for phytoremediation of Pb-contamined soil.  

PubMed

Characteristics of accumulation and tolerance of lead (Pb) in Quamolit pennata, Antirrhinum majus L. and Celosia cristata pyramidalis were investigated to identify Pb-accumulating plants. In this study, pot culture experiment was conducted to assess whether these plants are Pb-hyperaccumulators or accumulators. The results indicated that the Pb enrichment factor (concentration in plant/soil) and Pb translocation factor (concentration in shoot/root) of these plants were principally <1 in pot culture and concentration gradient experiments. However, the Pb concentration in Celosia cristata pyramidalis shoots was higher than 1000 mg kg(-1), the threshold concentration for a Pb-hyperaccumulator. Shoot biomass of Celosia cristata pyramidalis had no significantly (p < 0.05) variation compared to the control. Based on these results, only Celosia cristata pyramidalis could be identified as a Pb-accumulator. PMID:23487996

Cui, Shuang; Zhang, Tingan; Zhao, Shanlin; Li, Ping; Zhou, Qixing; Zhang, Qianru; Han, Qing

2013-01-01

215

Enhancement of phosphate absorption by garden plants by genetic engineering: a new tool for phytoremediation.  

PubMed

Although phosphorus is an essential factor for proper plant growth in natural environments, an excess of phosphate in water sources causes serious pollution. In this paper we describe transgenic plants which hyperaccumulate inorganic phosphate (Pi) and which may be used to reduce environmental water pollution by phytoremediation. AtPHR1, a transcription factor for a key regulator of the Pi starvation response in Arabidopsis thaliana, was overexpressed in the ornamental garden plants Torenia, Petunia, and Verbena. The transgenic plants showed hyperaccumulation of Pi in leaves and accelerated Pi absorption rates from hydroponic solutions. Large-scale hydroponic experiments indicated that the enhanced ability to absorb Pi in transgenic torenia (AtPHR1) was comparable to water hyacinth a plant that though is used for phytoremediation causes overgrowth problems. PMID:23984322

Matsui, Keisuke; Togami, Junichi; Mason, John G; Chandler, Stephen F; Tanaka, Yoshikazu

2013-08-04

216

Selenite precipitation by a rhizospheric strain of Stenotrophomonas sp. isolated from the root system of Astragalus bisulcatus: a biotechnological perspective  

Microsoft Academic Search

A bacterial strain (SeITE02), related to the species Stenotrophomonas maltophilia and resistant to selenite (SeIV) up to 50 mM in the growth medium, was isolated from rhizospheric soil of a selenium hyperaccumulator plant, the legume Astragalus bisulcatus. The influence of SeIV on the active growth of this Se-tolerant bacterial strain has been investigated in oxic conditions, along with the isolate's

Simona Di Gregorio; Silvia Lampis; Giovanni Vallini

2005-01-01

217

The mechanism of metal nanoparticle formation in plants: limits on accumulation  

Microsoft Academic Search

Metal nanoparticles have many potential technological applications. Biological routes to the synthesis of these particles\\u000a have been proposed including production by vascular plants, known as phytoextraction. While many studies have looked at metal\\u000a uptake by plants, particularly with regard to phytoremediation and hyperaccumulation, few have distinguished between metal\\u000a deposition and metal salt accumulation. This work describes the uptake of AgNO3,

R. G. Haverkamp; A. T. Marshall

2009-01-01

218

Involvement of auxin and nitric oxide in plant Cd-stress responses  

Microsoft Academic Search

Cadmium (Cd) toxicity inhibited the seedling growth while inducing the occurrences of lateral roots (LR) and adventitious\\u000a roots (AR). Further study indicated that auxin and nitric oxide (NO) are involved in the processes. In this study, we chose\\u000a model plant Arabidopsis thaliana and Cd-hyperaccumulator Solanum nigrum as material to examine the involvement of Cd-induced auxin redistribution in NO accumulation in

Jin Xu; Wenying Wang; Jianhang Sun; Yuan Zhang; Qing Ge; Liguo Du; Hengxia Yin; Xiaojing Liu

219

Effects of calcium on nickel tolerance and accumulation in Alyssum species and cabbage grown in nutrient solution  

Microsoft Academic Search

Nickel (Ni) phytoextraction using hyperaccumulator plant species to accumulate Ni from mineralized and contaminated soils\\u000a rich in Ni is undergoing commercial development. Serpentinite derived soils have a very low ratio of Ca\\/Mg among soils due\\u000a the nature of the parent rock. In crop plants, soil Ca reduces Ni uptake and phytotoxicity, so it is possible that the low\\u000a Ca of

Rufus L. Chaney; Kuang-Yu Chen; Yin-Ming Li; J. Scott Angle; Alan J. M. Baker

2008-01-01

220

Mechanisms of Plant Resistance to Metal and Metalloid Ions and Potential Biotechnological Applications  

Microsoft Academic Search

Metal and metalloid resistances in plant species and genotypes\\/accessions are becoming increasingly better understood at the\\u000a molecular and physiological level. Much of the recent focus into metal resistances has been on hyperaccumulators as these\\u000a are excellent systems to study resistances due to their very abnormal metal(loid) physiology and because of their biotechnological\\u000a potential. Advances into the mechanistic basis of metal(loid)

Andrew A. Meharg

2005-01-01

221

Analysis of Arsenic in Soil and Vegetation of a Contaminated Area in Zarshuran, Iran  

Microsoft Academic Search

To assess the potential for arsenic (As) hyperaccumulation of native plant species, plant and soil samples were collected from the Zarshuran area (north-western Iran), which has a history of As pollution from mining. Total and water-soluble As in the soil ranged from 11.2 to 6525 and from 0.004 to 13.08 mg kg, respectively. Among 89 plant species, the highest foliar

Naser Karimi; S. Majid Ghaderian; Hosein Maroofi; Henk Schat

2009-01-01

222

Arsenic-contaminated soils phytotoxicity studies with sunflower and sorghum  

Microsoft Academic Search

Background, Aim and Scope  Environmental pollution caused by arsenic (As) is a major ecological problem. There has been intense worldwide effort to find\\u000a As-hyperaccumulating plants that can be used in phytoremediation—the green-plant-assisted removal of chemical pollutants from\\u000a soils. For phytoremediation, it is natural to prefer cultivated rather than wild plants, because their agriculture is well\\u000a known. This study was conducted to

Yelena Vo Lyubun; Paul V. Kosterin; Elena A. Zakharova; Alexander A. Shcherbakov; Evgenii Eo Fedorov

2002-01-01

223

Application of plant growth-promoting endophytes (PGPE) isolated from Solanum nigrum L. for phytoextraction of Cd-polluted soils  

Microsoft Academic Search

Many plant growth-promoting endophytes (PGPE) can assist their host plants cope with contaminant-induced stress responses, which can improve plant growth. In this study, four heavy metals resistant endophytic bacteria, Serratia nematodiphila LRE07, Enterobacter aerogenes LRE17, Enterobacter sp. LSE04 and Acinetobacter sp. LSE06, were isolated from Cd-hyperaccumulator Solanum nigrum L. grown in metal-polluted soil. Their plant growth promoting properties such as

Liang Chen; Shenglian Luo; Xiao Xiao; Hanjun Guo; Jueliang Chen; Yong Wan; Bo Li; Taoying Xu; Qiang Xi; Chan Rao; Chengbin Liu; Guangming Zeng

2010-01-01

224

Arsenic speciation and transport in Pteris vittata L. and the effects on phosphorus in the xylem sap  

Microsoft Academic Search

The mechanism of arsenic (As) transport in Pteris vittata L. (Chinese brake fern), the first known arsenic-hyperaccumulating plant, is important to understand how arsenic is detoxified in the fern. The effects of arsenic concentration and form on arsenic and phosphorus in xylem sap were investigated using hydroponics systems. Ferns were subjected to 0, 10 or 50mgAsl?1 as As(III), As(V), DMA

G. M. Kertulis; L. Q. Ma; G. E. MacDonald; R. Chen; J. D. Winefordner; Y. Cai

2005-01-01

225

Shining light on metals in the environment  

SciTech Connect

Elucidating the speciation of heavy metals in the environment is paramount to understanding their potential mobility and bioavailability. Cutting-edge synchrotron-based techniques such as microfocused X-ray absorption fine-structure (XAFS) and X-ray fluorescence (XRF) spectroscopy and microtomography have revolutionized the way metal reactions and processes in natural systems are studied. In this article, we apply these intense-light tools to decipher metal forms (species) and associations in contaminated soils and metal-hyperaccumulating plants.

McNear, Jr., D.H.; Tappero, R.; Sparks, D.L. (Delaware)

2010-07-20

226

Selenium tolerance in Astragalus chrysochlorus : identification of a cDNA fragment encoding a putative Selenocysteine methyltransferase  

Microsoft Academic Search

Selenium (Se) plays an indispensable role in human nutrition and has been implicated to have important health benefits, including\\u000a being a cancer preventative agent. Selected members of the genus Astragalus (Fabaceae) are known for their ability to accumulate high levels of selenium, mainly in the form of methyl-selenocysteine\\u000a (MeSeCys). The Se-hyperaccumulator Astragalus bisulcatus metabolizes >90% of the accumulated Se into

?ule Ar?; Özgür Çak?r; Neslihan Turgut-Kara

2010-01-01

227

Colonization and Modulation of Host Growth and Metal Uptake by Endophytic Bacteria of Sedum alfredii  

Microsoft Academic Search

Sedum alfredii Hance is a Zn and Cd co-hyperaccumulating plant species found in an old mining area in China. Four bacterial strains, Burkholderia sp. SaZR4, Burkholderia sp. SaMR10, Sphingomonas sp. SaMR12 and Variovorax sp. SaNR1, isolated from surface-sterilized S. alfredii plants were used to investigate their endophytic nature and root colonization patterns and effects on phytoextraction of Zn and Cd.

Xincheng Zhang; Li Lin; Zhiqiang Zhu; Xiaoe Yang; Yuyan Wang; Qianli An

2012-01-01

228

Phytofiltration of Arsenic-Contaminated Groundwater Using Pteris Vittata L.: Effect of Plant Density and Nitrogen and Phosphorus Levels  

Microsoft Academic Search

This field-scale hydroponic experiment investigated the effects of plant density and nutrient levels on arsenic (As) removal by the As-hyperaccumulator Pteris vittata L. (Chinese brake fern). All ferns were grown in plastic tanks containing 30 L of As-contaminated groundwater (130 ?g·L As) collected from South Florida. The treatments consisted of four plant densities (zero, one, two, or four plants per

Seenivasan Natarajan; Robert H. Stamps; Uttam K. Saha; Lena Q. Ma

2008-01-01

229

Analysis of the metabolome and transcriptome of Brassica carinata seedlings after lithium chloride exposure  

Microsoft Academic Search

Exposure of B. carinata seedlings to increasing concentrations of a non-physiological ion, lithium, showed significant effects on the germination rate, root length, chlorophyll content and fresh weight in brown-seeded and yellow-seeded near-isogenic lines. Metal content analysis and phytochemical profiling indicated that lithium hyper-accumulated and the lipid and phenolic composition dramatically changed in brown-seeded seedlings. Here, sinapic acid esters and chloroplast

Xiang Li; Peng Gao; Branimir Gjetvaj; Neil Westcott; Margaret Y. Gruber

2009-01-01

230

Conjugative plasmid mediated inducible nickel resistance in Hafnia alvei 5-5  

Microsoft Academic Search

  \\u000a \\u000a Hafnia alvei 5-5, isolated from a soil-litter mixture underneath the canopy of the nickel-hyperaccumulating tree Sebertia acuminata (Sapotaceae) in New Caledonia, was found to be resistant to 30 mM Ni2+ or 2 mM Co2+. The 70-kb plasmid, pEJH 501, was transferred by conjugation to Escherichia coli, Serratia marcescens, and Klebsiella oxytoca. Transconjugant strains expressed inducible nickel resistance to between 5 and

Jeong Eun Park; Kho Eun Young; Hans-Günter Schlegel; Ho Gun Rhie; Ho Sa Lee

2003-01-01

231

Antioxidant defense system in leaves of Indian mustard ( Brassica juncea ) and rape ( Brassica napus ) under cadmium stress  

Microsoft Academic Search

Plant species capable of hyper-accumulating heavy metals are of considerable interest for phytoremediation, and differ in\\u000a their ability to accumulate metals from environment. Using two brassica species (Brassica juncea and Brassica napus), nutrient solution experiments were conducted to study variation in tolerance to cadmium (Cd) toxicity based on (1) lipid\\u000a peroxidation and (2) changes in antioxidative defense system in leaves

Issam Nouairi; Wided Ben Ammar; Nabil Ben Youssef; Douja Daoud Ben Miled; Mohamed Habib Ghorbal; Mokhtar Zarrouk

2009-01-01

232

EDTA-assisted Pb phytoextraction.  

PubMed

Pb is one of the most widespread and metal pollutants in soil. It is generally concentrated in surface layers with only a minor portion of the total metal found in soil solution. Phytoextraction has been proposed as an inexpensive, sustainable, in situ plant-based technology that makes use of natural hyperaccumulators as well as high biomass producing crops to help rehabilitate soils contaminated with heavy metals without destructive effects on soil properties. The success of phytoextraction is determined by the amount of biomass, concentration of heavy metals in plant, and bioavailable fraction of heavy metals in the rooting medium. In general, metal hyperaccumulators are low biomass, slow growing plant species that are highly metal specific. For some metals such as Pb, there are no hyperaccumulator plant species known to date. Although high biomass-yielding non-hyperaccumulator plants lack an inherent ability to accumulate unusual concentrations of Pb, soil application of chelating agents such as EDTA has been proposed to enhance the metal concentration in above-ground harvestable plant parts through enhancing the metal solubility and translocation from roots to shoots. Leaching of metals due to enhanced mobility during EDTA-assisted phytoextraction has been demonstrated as one of the potential hazards associated with this technology. Due to environmental persistence of EDTA in combination with its strong chelating abilities, the scientific community is moving away from the use of EDTA in phytoextraction and is turning to less aggressive alternative strategies such as the use of organic acids or more degradable APCAs (aminopolycarboxylic acids). We have therefore arrived at a point in phytoremediation research history in which we need to distance ourselves from EDTA as a proposed soil amendment within the context of phytoextraction. However, valuable lessons are to be learned from over a decade of EDTA-assisted phytoremediation research when considering the implementation of more degradable alternatives in assisted phytoextraction practices. PMID:19121533

Saifullah; Meers, E; Qadir, M; de Caritat, P; Tack, F M G; Du Laing, G; Zia, M H

2009-01-01

233

Analysis of Sulfur And Selenium Assimilation in 'Astragalus' Plants With Varying Capacities to Accumulate Selenium  

SciTech Connect

Several Astragalus species have the ability to hyperaccumulate selenium (Se) when growing in their native habitat. Given that the biochemical properties of Se parallel those of sulfur (S), we examined the activity of key S assimilatory enzymes ATP sulfurylase (ATPS), APS reductase (APR), and serine acetyltransferase (SAT), as well as selenocysteine methyltransferase (SMT), in eight Astragalus species with varying abilities to accumulate Se. Se hyperaccumulation was found to positively correlate with shoot accumulation of S-methylcysteine (MeCys) and Se-methylselenocysteine (MeSeCys), in addition to the level of SMT enzymatic activity. However, no correlation was observed between Se hyperaccumulation and ATPS, APR, and SAT activities in shoot tissue. Transgenic Arabidopsis thaliana overexpressing both ATPS and APR had a significant enhancement of selenate reduction as a proportion of total Se, whereas SAT overexpression resulted in only a slight increase in selenate reduction to organic forms. In general, total Se accumulation in shoots was lower in the transgenic plants overexpressing ATPS, PaAPR, and SAT. Root growth was adversely affected by selenate treatment in both ATPS and SAT overexpressors and less so in the PaAPR transgenic plants. Such observations support our conclusions that ATPS and APR are major contributors of selenate reduction in planta. However, Se hyperaccumulation in Astragalus is not driven by an overall increase in the capacity of these enzymes, but rather by either an increased Se flux through the S assimilatory pathway, generated by the biosynthesis of the sink metabolites MeCys or MeSeCys, or through an as yet unidentified Se assimilation pathway.

Sors, T.G.; Ellis, D.R.; Na, G.Nam.; Lahner, B.; Lee, S.; Leustek, T.; Pickering, I.J.; Salt, D.E.; /Purdue U. /Rutgers U., Piscataway /Saskatchewan U.

2007-08-08

234

Removing heavy metals from synthetic effluents using “kamikaze” Saccharomyces cerevisiae cells  

Microsoft Academic Search

One key step of the bioremediation processes designed to clean up heavy metal contaminated environments is growing resistant\\u000a cells that accumulate the heavy metals to ensure better removal through a combination of biosorption and continuous metabolic\\u000a uptake after physical adsorption. Saccharomyces cerevisiae cells can easily act as cation biosorbents, but isolation of mutants that are both hyperaccumulating and tolerant to

Lavinia Ruta; Codruta Paraschivescu; Mihaela Matache; Sorin Avramescu; Ileana Cornelia Farcasanu

2010-01-01

235

Screening of plant species for phytoremediation of uranium, thorium, barium, nickel, strontium and lead contaminated soils from a uranium mill tailings repository in South China.  

PubMed

The concentrations of uranium, thorium, barium, nickel, strontium and lead in the samples of the tailings and plant species collected from a uranium mill tailings repository in South China were analyzed. Then, the removal capability of a plant for a target element was assessed. It was found that Phragmites australis had the greatest removal capabilities for uranium (820 ?g), thorium (103 ?g) and lead (1,870 ?g). Miscanthus floridulus had the greatest removal capabilities for barium (3,730 ?g) and nickel (667 ?g), and Parthenocissus quinquefolia had the greatest removal capability for strontium (3,920 ?g). In this study, a novel coefficient, termed as phytoremediation factor (PF), was proposed, for the first time, to assess the potential of a plant to be used in phytoremediation of a target element contaminated soil. Phragmites australis has the highest PFs for uranium (16.6), thorium (8.68), barium (10.0) and lead (10.5). Miscanthus floridulus has the highest PF for Ni (25.0). Broussonetia papyrifera and Parthenocissus quinquefolia have the relatively high PFs for strontium (28.1 and 25.4, respectively). On the basis of the definition for a hyperaccumulator, only Cyperus iria and Parthenocissus quinquefolia satisfied the criteria for hyperaccumulator of uranium (36.4 ?g/g) and strontium (190 ?g/g), and could be the candidates for phytoremediation of uranium and strontium contaminated soils. The results show that the PF has advantage over the hyperaccumulator in reflecting the removal capabilities of a plant for a target element, and is more adequate for assessing the potential of a plant to be used in phytoremediation than conventional method. PMID:21523506

Li, Guang-yue; Hu, Nan; Ding, De-xin; Zheng, Ji-fang; Liu, Yu-long; Wang, Yong-dong; Nie, Xiao-qin

2011-04-27

236

Composition, speciation and distribution of iron minerals in Imperata cylindrica.  

PubMed

A comparative study of the roots, rhizomes and leaves of an iron hyperaccumulator plant, Imperata cylindrica, isolated from the banks of an extreme acidic environment, using complementary techniques: Mösbauer spectroscopy (MS), X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled to energy-dispersive X-ray microanalysis (EDAX) and transmission electron microscopy (TEM), has shown that two main biominerals, jarosite and ferrihydrate-ferritin, accumulate in the different tissues. Jarosite accumulates mainly in roots and rhizomes, while ferritin has been detected in all the structures. A model of iron management in I. cylindrica is presented. PMID:17502153

Amils, Ricardo; de la Fuente, Vicenta; Rodríguez, Nuria; Zuluaga, Javier; Menéndez, Nieves; Tornero, Jesús

2007-03-19

237

Isolation of Gibberellin Precursors from Heavily Pigmented Tissues 1  

PubMed Central

The kauranoid precursors of gibberellins are difficult to isolate from heavily pigmented plant tissues. In this paper, we describe relatively simple and efficient procedures for the purification of these compounds from tissues containing chlorophyll and other high molecular weight pigments. Extracts of shoots from Thlaspi arvense L. were subjected first to size exclusion chromatography using ethyl acetate as the eluting solvent. This procedure resulted in the separation of kauranoids as a class of compounds from chlorophyll. Typically, a 90% reduction in mass of the kauranoid enriched-fraction was observed. This fraction was subjected to reverse phase high performance liquid chromatography and individual fractions analyzed by combined gas chromatography-mass spectrometry. Five kauranoids were identified in shoot extracts of T. arvense: ent-kaur-16-ene, ent-kaur-16-en-19-ol, ent-kaur-16-en-19-oic acid, trachylobanoic acid, and 7?, 13-dihydroxykaurenolide. The metabolic relationships of these compounds to the gibberellins previously identified in this species (JD Metzger, MC Mardaus [1986] Plant Physiol 80: 396-402) are discussed. In addition, the utility of size exclusion chromatography in preparative situations is demonstrated by the purification of ent-kaurenoic acid in milligram quantities from the florets of Helianthus annuus L.

Metzger, James D.; Hazebroek, Jan P.

1989-01-01

238

A comparative study of salt tolerance parameters in 11 wild relatives of Arabidopsis thaliana  

PubMed Central

Salinity is an abiotic stress that limits both yield and the expansion of agricultural crops to new areas. In the last 20 years our basic understanding of the mechanisms underlying plant tolerance and adaptation to saline environments has greatly improved owing to active development of advanced tools in molecular, genomics, and bioinformatics analyses. However, the full potential of investigative power has not been fully exploited, because the use of halophytes as model systems in plant salt tolerance research is largely neglected. The recent introduction of halophytic Arabidopsis-Relative Model Species (ARMS) has begun to compare and relate several unique genetic resources to the well-developed Arabidopsis model. In a search for candidates to begin to understand, through genetic analyses, the biological bases of salt tolerance, 11 wild relatives of Arabidopsis thaliana were compared: Barbarea verna, Capsella bursa-pastoris, Hirschfeldia incana, Lepidium densiflorum, Malcolmia triloba, Lepidium virginicum, Descurainia pinnata, Sisymbrium officinale, Thellungiella parvula, Thellungiella salsuginea (previously T. halophila), and Thlaspi arvense. Among these species, highly salt-tolerant (L. densiflorum and L. virginicum) and moderately salt-tolerant (M. triloba and H. incana) species were identified. Only T. parvula revealed a true halophytic habitus, comparable to the better studied Thellungiella salsuginea. Major differences in growth, water transport properties, and ion accumulation are observed and discussed to describe the distinctive traits and physiological responses that can now be studied genetically in salt stress research.

Orsini, Francesco; D'Urzo, Matilde Paino; Inan, Gunsu; Serra, Sara; Oh, Dong-Ha; Mickelbart, Michael V.; Consiglio, Federica; Jeong, Jae Cheol; Yun, Dae-Jin; Bohnert, Hans J.; Bressan, Ray A.; Maggio, Albino

2010-01-01

239

Candidate gene analysis of organ pigmentation loci in the Solanaceae.  

PubMed

Ten structural genes from the Capsicum (pepper) carotenoid biosynthetic pathway have been localized on a (Capsicum annuum x Capsicum chinense)F(2) genetic map anchored in Lycopersicon (tomato). The positions of these genes were compared with positions of the same genes in tomato when known, and with loci from pepper, potato, and tomato that affect carotenoid levels in different tissues. C2, one of three phenotypically defined loci determining pepper fruit color, cosegregated with phytoene synthase. The capsanthin-capsorubin synthase (Ccs) locus, shown previously to cosegregate with Y, another pepper fruit color locus, mapped to pepper chromosome 6. Other structural genes in pepper corresponded to loci affecting carotenoid production as follows: Ccs in pepper and the B locus for hyperaccumulation of beta-carotene in tomato fruit mapped to homeologous regions; the position of the lycopene beta-cyclase gene in pepper may correspond to the lutescent-2 mutation in tomato; and the lycopene epsilon-cyclase locus in pepper corresponded to the lycopene epsilon-cyclase locus/Del mutation for hyperaccumulation of delta-carotene in tomato fruit. Additional associations were seen between the structural genes and previously mapped loci controlling quantitative variation in pepper and tomato fruit color. These results demonstrate that comparative analyses using candidate genes may be used to link specific metabolic phenotypes and loci that affect these phenotypes in related species. PMID:11027328

Thorup, T A; Tanyolac, B; Livingstone, K D; Popovsky, S; Paran, I; Jahn, M

2000-10-10

240

Arsenic in the rhizosphere soil solution of ferns.  

PubMed

The aim of this study was to explore the evidence of arsenic hyperaccumulation in plant rhizosphere solutions. Six common fern plants were selected and grown in three types of substrate: arsenic (As) -tailings, As-spiked soil, and soil-As-tailing composites. A rhizobox was designed with an in-situ collection of soil solutions to analyze changes in the As concentration and valence as well as the pH, dissolved organic carbon (DOC) and total nitrogen (TN). Arsenite composed less than 20% of the total As, and As depletion was consistent with N depletion in the rhizosphere solutions of the various treatments. The As concentrations in the rhizosphere and non-rhizosphere solutions in the presence of plants were lower than in the respective controls without plants, except for in the As-spiked soils. The DOC concentrations were invariably higher in the rhizosphere versus non-rhizosphere solutions from the various plants; however, no significant increase in the DOC content was observed in Pteris vittata, in which only a slight decrease in pH appeared in the rhizosphere compared to non-rhizosphere solutions. The results showed that As reduction by plant roots was limited, acidification-induced solubilization was not the mechanism for As hyperaccumulation. PMID:22908657

Wei, Chaoyang; Zheng, Huan; Yu, Jiangping

2012-12-01

241

A transcriptomic network underlies microstructural and physiological responses to cadmium in Populus x canescens.  

PubMed

Bark tissue of Populus × canescens can hyperaccumulate cadmium, but microstructural, transcriptomic, and physiological response mechanisms are poorly understood. Histochemical assays, transmission electron microscopic observations, energy-dispersive x-ray microanalysis, and transcriptomic and physiological analyses have been performed to enhance our understanding of cadmium accumulation and detoxification in P. × canescens. Cadmium was allocated to the phloem of the bark, and subcellular cadmium compartmentalization occurred mainly in vacuoles of phloem cells. Transcripts involved in microstructural alteration, changes in nutrition and primary metabolism, and stimulation of stress responses showed significantly differential expression in the bark of P. × canescens exposed to cadmium. About 48% of the differentially regulated transcripts formed a coregulation network in which 43 hub genes played a central role both in cross talk among distinct biological processes and in coordinating the transcriptomic regulation in the bark of P. × canescens in response to cadmium. The cadmium transcriptome in the bark of P. × canescens was mirrored by physiological readouts. Cadmium accumulation led to decreased total nitrogen, phosphorus, and calcium and increased sulfur in the bark. Cadmium inhibited photosynthesis, resulting in decreased carbohydrate levels. Cadmium induced oxidative stress and antioxidants, including free proline, soluble phenolics, ascorbate, and thiol compounds. These results suggest that orchestrated microstructural, transcriptomic, and physiological regulation may sustain cadmium hyperaccumulation in P. × canescens bark and provide new insights into engineering woody plants for phytoremediation. PMID:23530184

He, Jiali; Li, Hong; Luo, Jie; Ma, Chaofeng; Li, Shaojun; Qu, Long; Gai, Ying; Jiang, Xiangning; Janz, Dennis; Polle, Andrea; Tyree, Melvin; Luo, Zhi-Bin

2013-03-25

242

Effects of selenium accumulation on reproductive functions in Brassica juncea and Stanleya pinnata  

PubMed Central

Selenium (Se) is an essential micronutrient for many organisms, but is also a toxin and environmental pollutant at elevated levels. Due to its chemical similarity to sulphur, most plants readily take up and assimilate Se. Se accumulators such as Brassica juncea can accumulate Se between 0.01% and 0.1% of dry weight (DW), and Se hyperaccumulators such as Stanleya pinnata (Brassicaeae) contain between 0.1% and 1.5% DW of Se. While Se accumulation offers the plant a variety of ecological benefits, particularly protection from herbivory, its potential costs are still unexplored. This study examines the effects of plant Se levels on reproductive functions. In B. juncea, Se concentrations >0.05–0.1% caused decreases in biomass, pollen germination, individual seed and total seed weight, number of seeds produced, and seed germination. In S. pinnata there was no negative effect of increased Se concentration on pollen germination. In cross-pollination of B. juncea plants with different Se levels, both the maternal and paternal Se level affected reproduction, but the maternal Se concentration had the most pronounced effect. Interestingly, high-Se maternal plants were most efficiently pollinated by Se-treated paternal plants. These data provide novel insights into the potential reproductive costs of Se accumulation, interactive effects of Se in pollen grains and in the pistil, and the apparent evolution of physiological tolerance mechanisms in hyperaccumulators to avoid reproductive repercussions.

Prins, Christine N.; Hantzis, Laura J.; Quinn, Colin F.; Pilon-Smits, Elizabeth A. H.

2011-01-01

243

Proline improves copper tolerance in chickpea (Cicer arietinum).  

PubMed

The present study suggests the involvement of proline in copper tolerance of four genotypes of Cicer arietinum (chickpea). Based on the data of tolerance index and lipid peroxidation, the order for copper tolerance was as follows: RSG 888 > CSG 144 > CSG 104 > RSG 44 in the selected genotypes. The basis of differential copper tolerance in chickpea genotypes was characterized by analyzing, antioxidant enzymes (superoxide dismutase, ascorbated peroxidase and catalase), phytochelatins, copper uptake, and proline accumulation. Chickpea genotypes showed stimulated superoxide dismutase activity at all tested concentrations of copper, but H(2)O(2) decomposing enzymes especially; ascorbate peroxidase did not increase with 25 and 50 microM copper treatments. Catalase activity, however, increased at lower copper concentrations but failed to stimulate at 50 microM copper. Such divergence in responses of these enzymes minimizes their importance in protecting chickpea against copper stress. The sensitive genotypes showed greater enhancement of phytochelatins than that of tolerant genotypes. Hence, the possibility of phytochelatins in improving copper tolerance in the test plant is also excluded. Interestingly, the order of proline accumulation in the chickpea genotypes (RSG 888 > CSG 144 > CSG 104 > RSG 44) was exactly similar to the order of copper tolerance. Based on hyperaccumulation of proline in tolerant genotype (RSG 44) and the reduction and improvement of lipid peroxidation and tolerance index, respectively, by proline pretreatment, we conclude that hyperaccumulation of proline improves the copper tolerance in chickpea. PMID:20625778

Singh, Vijeta; Bhatt, Indu; Aggarwal, Anjali; Tripathi, Bhumi Nath; Munjal, Ashok Kumar; Sharma, Vinay

2010-07-13

244

Mechanisms of lichen resistance to metallic pollution  

SciTech Connect

Some lichens have a unique ability to grow in heavily contaminated areas due to the development of adaptative mechanisms allowing a high tolerance to metals. Here the authors report on the chemical forms of Pb and Zn in the metal hyperaccumulator Diploschistes muscorum and of Pb in the metal tolerant lichen Xanthoria parietina. The speciation of Zn and Pb has been investigated by powder X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy using the advanced third-generation synchrotron radiation source of the European synchrotron radiation facility (ESRF in Grenoble). This study reveals that in both lichens cells are protected from toxicity by complexation of heavy metals, but the strategies differ: in D. muscorum, Pb and Zn are accumulated through an enhanced synthesis of oxalate, which precipitates toxic elements as insoluble salts, whereas in X. parietina, Pb is complexed to carboxylic groups of the fungal cell walls. The authors conclude that hyperaccumulation of metals results from a reactive mechanism of organic acid production, whereas metallo-tolerance is achieved by a passive complexation to existing functional groups.

Sarret, C.; Manceau, A.; Eybert-Berard, L. [Univ. of Grenoble and CNRS (France). Environmental Geochemistry Group; Cuny, D.; Haluwyn, C. van [Lab. de Botanique et de Cryptogamie, Lille (France); Deruelle, S. [Institut d`Ecologie, Paris (France); Hazemann, J.L.; Menthonnex, J.J. [Univ. of Grenoble and CNRS (France). Environmental Geochemistry Group]|[CNRS, Grenoble (France). Lab. de Cristallographie; Soldo, Y. [CNRS, Grenoble (France). Lab. de Cristallographie

1998-11-01

245

Arbuscular mycorrhizal fungi enhance both absorption and stabilization of Cd by Alfred stonecrop (Sedum alfredii Hance) and perennial ryegrass (Lolium perenne L.) in a Cd-contaminated acidic soil.  

PubMed

A greenhouse pot experiment was conducted to compare the phytoextraction efficiencies of Cd by hyper-accumulating Alfred stonecrop (Sedum alfredii Hance) and fast-growing perennial ryegrass (Lolium perenne L.) from a Cd-contaminated (1.6mgkg(-1)) acidic soil, and their responses to the inoculations of two arbuscular mycorrhizal (AM) fungal strains, Glomus caledonium 90036 (Gc) and Glomus mosseae M47V (Gm). Ryegrass and stonecrop were harvested after growing for 9 and 27 wk, respectively. Without AM fungal inoculation, the weekly Cd extraction by stonecrop (8.0?gpot(-1)) was 4.3 times higher than that by ryegrass (1.5?gpot(-1)). Both Gc and Gm significantly increased (P<0.05) root mycorrhizal colonization rates, soil acid phosphatase activities, and available P concentrations, and thereby plant P absorptions (except for Gm-inoculated ryegrass), shoot biomasses, and Cd absorptions (except for Gm-inoculated stonecrop), while only Gc-inoculated stonecrop significantly accelerated (P<0.05) the phytoextraction efficiency of Cd by 78%. In addition, both Gc and Gm significantly decreased (P<0.05) phytoavailable Cd concentrations by 21-38% via elevating soil pH. The results suggested the potential application of hyper-accumulating Alfred stonecrop associated with AM fungi (notably Gc) for both extraction and stabilization of Cd in the in situ treatment of Cd-contaminated acidic soil. PMID:24011894

Hu, Junli; Wu, Shengchun; Wu, Fuyong; Leung, Ho Man; Lin, Xiangui; Wong, Ming Hung

2013-09-05

246

PHOSPHATE INCORPORATION DURING GLYCOGEN SYNTHESIS AND LAFORA DISEASE  

PubMed Central

SUMMARY Glycogen is a branched polymer of glucose that serves as an energy store. Phosphate, a trace constituent of glycogen, has profound effects on glycogen structure and phosphate hyperaccumulation is linked to Lafora disease, a fatal progressive myoclonus epilepsy that can be caused by mutations of laforin, a glycogen phosphatase. However, little is known about the metabolism of glycogen phosphate. We demonstrate here that the biosynthetic enzyme glycogen synthase, which normally adds glucose residues to glycogen, is capable of incorporating the ?-phosphate of its substrate UDP-glucose at a rate of one phosphate per approximately 10,000 glucoses, in what may be considered a catalytic error. We show that the phosphate in glycogen is present as C2 and C3 phosphomonoesters. Since hyperphosphorylation of glycogen causes Lafora disease, phosphate removal by laforin may thus be considered a repair or damage control mechanism.

Tagliabracci, Vincent S.; Heiss, Christian; Karthik, Chandra; Contreras, Christopher J.; Glushka, John; Ishihara, Mayumi; Azadi, Parastoo; Hurley, Thomas D.; DePaoli-Roach, Anna A.; Roach, Peter J.

2011-01-01

247

Phytoremediation potential of paragrass--an in situ approach for chromium contaminated soil.  

PubMed

The present in situ phytoextraction approach uses paragrass (Brachiaria mutica (Forssk) Stapf) as a hyper accumulator for attenuation of chromium level in soil and mine waste water at South Kaliapani chromite mine area of Orissa. The bioconcentration factor (BCF) for Cr was maximum (0.334) in 100 days grown paragrass weeds. Transportation index (Ti) i.e. 6.16 and total accumulation rate (TAR) i.e. 8.2 mg kg(-1)day(-1) was maximum in 125 days old paragrass grown in Cr contaminated experimental cultivated plots. Cr bioaccumulation in roots was nearly 1000 times more than shoots. Paragrass showed luxuriant growth with massive fibrous roots when grown over Cr contaminated soils (11,170 mg/ kg dry soil). Cr bioaccumulation varies significantly with plant age, biomass and level of Cr contamination in irrigated mine waste water and soil. Paragrass could be used as hyperaccumulators as it showed rapid massive growth with a high tolerance to Cr. PMID:22908645

Mohanty, Monalisa; Patra, Hemanta Kumar

2012-09-01

248

Selenometabolomics explored by speciation.  

PubMed

Selenium (Se) belongs to the same group as sulfur in the periodic table but possesses certain chemical properties characteristic of a metal. It is an essential element in animals but becomes severely toxic when the amount ingested exceeds the required level. On the other hand, Se is not essential in plants although some plants are Se hyperaccumulators. Se changes into several chemical forms when metabolized. Thus, the identification of selenometabolites would enable us to formulate a metabolic chart of Se. Recently, speciation analysis by hyphenated techniques has contributed immensely to the study of selenometabolomes, i.e., the entirety of selenometabolites. Indeed, speciation has unveiled some unique selenometabolites in biological samples. The aim of this review is to present newly identified selenometabolites in animals and plants by speciation using hyphenated techniques and to delineate the perspectives of Se biology and toxicology from the viewpoint of speciation. PMID:23123457

Ogra, Yasumitsu; Anan, Yasumi

2012-01-01

249

Phytoremediation of Ionic and Methyl Mercury Pollution  

SciTech Connect

Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to control the chemical speciation, electrochemical state, transport, and aboveground binding of mercury in order to manage this toxicant. To advance this mercury phytoremediation strategy, our planned research focuses on the following Specific Aims: (1) to increase the transport of mercury to aboveground tissue; (2) to identify small mercury binding peptides that enhance hyperaccumulation aboveground; (3) to test the ability of multiple genes acting together to enhance resistance and hyperaccumulation; (4) to construct a simple molecular system for creating male/female sterility, allowing engineered grass, shrub, and tree species to be released indefinitely at contaminated sites; (5) to test the ability of transgenic cottonwood and rice plants to detoxify ionic mercury and prevent methylmercury release from contaminated sediment; and (6) to initiate field testing with transgenic cottonwood and rice for the remediation of methylmercury and ionic mercury. The results of these experiments will enable the phytoremediation of methyl- and ionic mercury by a wide spectrum of deep-rooted, fast-growing plants adapted to diverse environments. We have made significant progress on all six of these specific aims as summarized below.

Meagher, Richard B.

2005-06-01

250

The tolerance efficiency of Panicum maximum and Helianthus annuus in TNT-contaminated soil and nZVI-contaminated soil.  

PubMed

This study was designed to compare the initial method for phytoremediation involving germination and transplantation. The study was also to determine the tolerance efficiency of Panicum maximum (Purple guinea grass) and Helianthus annuus (Sunflower) in TNT-contaminated soil and nZVI-contaminated soil. It was found that the transplantation of Panicum maximum and Helianthus annuus was more suitable than germination as the initiate method of nano-phytoremediation potting test. The study also showed that Panicum maximum was more tolerance than Helianthus annuus in TNT and nZVI-contaminated soil. Therefore, Panicum maximum in the transplantation method should be selected as a hyperaccumulated plant for nano-phytoremediation potting tests. Maximum tolerance dosage of Panicum maximum to TNT-concentration soil was 320 mg/kg and nZVI-contaminated soil was 1000 mg/kg in the transplantation method. PMID:22702809

Jiamjitrpanich, Waraporn; Parkpian, Preeda; Polprasert, Chongrak; Laurent, François; Kosanlavit, Rachain

2012-01-01

251

Making phytoremediation work better: maximizing a plant's growth potential in the midst of adversity.  

PubMed

While a number of different plants can either breakdown a variety of organic contaminants or hyperaccumulate metals from the environment, even the most efficient of those plants is typically inhibited by the presence of the toxicant(s). The plant stress that is induced by the presence of various environmental toxicants typically limits a plant's growth and ultimately its ability to phytoremediate the toxicant(s). Here, it is argued that the simple strategy of adding plant growth-promoting bacteria (preferably endophytes) that reduce plant ethylene levels by ACC deaminase activity and have the ability to synthesize the phytohoromone IAA, and are used to phytoremediate various toxicants can significantly (and often dramatically) increase both plant growth and phytoremediation activity in the presence of those toxicants. PMID:22046748

Glick, Bernard R; Stearns, Jennifer C

2011-01-01

252

Perspectives of bacterial ACC deaminase in phytoremediation.  

PubMed

Phytoremediation of contaminated soil and water environments is regulated and coordinated by the plant root system, yet root growth is often inhibited by pollutant-induced stress. Prolific root growth could maximize rates of hyperaccumulation of inorganic contaminants or rhizodegradation of organic pollutants, and thus accelerate phytoremediation. Accelerated ethylene production in response to stress induced by contaminants is known to inhibit root growth and is considered as a major limitation in improving phytoremediation efficiency. Recent work shows that bacterial 1-aminocyclopropane-1-carboxylate (ACC) deaminase regulates ethylene levels in plants by metabolizing its precursor ACC into alpha-ketobutyric acid and ammonia. Plants inoculated with ACC deaminase bacteria or transgenic plants that express bacterial ACC deaminase genes can regulate their ethylene levels and consequently contribute to a more extensive root system. Such proliferation of roots in contaminated soil can lead to enhanced uptake of heavy metals or rhizodegradation of xenobiotics. PMID:17573137

Arshad, Muhammad; Saleem, Muhammad; Hussain, Sarfraz

2007-06-18

253

Zinc accumulation and synthesis of ZnO nanoparticles using Physalis alkekengi L.  

PubMed

A field survey and greenhouse experiments were conducted using Physalis alkekengi L. to investigate strategies of phytoremediation. In addition, ZnO nanoparticles were synthesized using P. alkekengi. P. alkekengi plants grew healthily at Zn levels from 50 to 5000 mg kg(-1) in soils. The plants incorporated Zn into their aerial parts (with mean dry weight values of 235-10,980 mg kg(-1)) and accumulated biomass (with a mean dry weight of 25.7 g plant(-1)) during 12 weeks. The synthesized ZnO nanoparticles showed a polydisperse behavior and had a mean size of 72.5 nm. The results indicate that P. alkekengi could be used for the remediation of zinc-contaminated soils. Moreover, the synthetic method of synthesizing ZnO nanoparticles from Zn hyperaccumulator plants constitutes a new insight into the recycling of metals in plant sources. PMID:21549461

Qu, Jiao; Yuan, Xing; Wang, Xinhong; Shao, Peng

2011-05-06

254

A phytogeochemical study of the Trás-os-Montes region (NE Portugal): possible species for plant-based soil remediation technologies.  

PubMed

Phytoremediation techniques are now considered to be promising alternatives to conventional techniques for the remediation of diffused or moderately contaminated soils. Despite their growing acceptance relatively few plant species have been studied for phytoremediation purposes. Further geobotanical surveys and plant screenings are necessary since these could lead to the identification of additional species with potential value for such applications. Serpentine areas could prove valuable sources of such plants. In this study heavy metal accumulation was determined in the flora associated with ultramafic and non-ultramafic soils of the Trás-os-Montes region of NE Portugal. Study sites were selected to represent a wide range of soil-forming rocks (serpentinized (S), ultrabasic (UB), basic (B) and acid (migmatite, M and schists, SC) rocks) and plant metal accumulation was related to soil metal bioavailability. Nine plant species (representing 7 families) were sampled including the Ni hyperaccumulator Alyssum serpyllifolium subsp. lusitanicum. The greatest metal accumulation, transport (leaf[metal]:root[metal]) and bioaccumulation (leaf[metal]/soil[metal]) was found in four of the non metal-hyperaccumulating species: Cistus ladanifer, Lavandula stoechas, Plantago subulata subsp. radicata and Thymus mastichina. Metal accumulation depended on both the plant species and the edaphic conditions at its provenance. While P. subulata is of less interest due to its low biomass the remaining three species could be of use in phytoremediation technologies such as phytoextraction, and particularly in soils contaminated with Cr, Mn and Zn. These three species are also of economic interest due to their oil and fragrance producing biomass. PMID:16399000

Díez Lázaro, J; Kidd, P S; Monterroso Martínez, C

2006-02-01

255

Phytoremediation of Ionic and Methyl Mercury Pollution  

SciTech Connect

Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems. Our current strategy is to engineer plants to control the chemical speciation, electrochemical state, transport, and aboveground binding of mercury in order to manage this toxicant.

Meagher, Richard B.

2005-06-01

256

The extent of arsenic and of metal uptake by aboveground tissues of Pteris vittata and Cyperus involucratus growing in copper- and cobalt-rich tailings of the Zambian copperbelt.  

PubMed

The extent of arsenic (As) and metal accumulation in fronds of the As hyperaccumulator Pteris vittata (Chinese brake fern) and in leaves of Cyperus involucratus, which grow on the surface of an old flotation tailings pond in the Zambian Copperbelt province, was studied. The tailings consist of two types of material with distinct chemical composition: (1) reddish-brown tailings rich in As, iron (Fe), and other metals, and (2) grey-green tailings with a lower content of As, Fe, and other metals, apart from manganese (Mn). P. vittata accumulates from 2350 to 5018 ?g g(-1) As (total dry weight [dw]) in its fronds regardless of different total and plant-available As concentrations in both types of tailings. Concentrations of As in C. involucratus leaves are much lower (0.24-30.3 ?g g(-1) dw). Contents of copper (Cu) and cobalt (Co) in fronds of P. vittata (151-237 and 18-38 ?g g(-1) dw, respectively) and in leaves of C. involucratus (96-151 and 9-14 ?g g(-1) dw, respectively) are high, whereas concentrations of other metals (Fe, Mn, and zinc [Zn]) are low and comparable with contents of the given metals in common plants. Despite great differences in metal concentrations in the two types of deposited materials, concentrations of most metals in plant tissues are very similar. This indicates an exclusion or avoidance mechanism operating when concentrations of the metals in substrate are particularly high. The results of the investigation show that Chinese brake fern is not only a hyperaccumulator of As but has adapted itself to high concentrations of Cu and Co in flotation tailings of the Zambian Copperbelt. PMID:20949352

K?íbek, Bohdan; Mihaljevi?, Martin; Sracek, Ondra; Knésl, Ilja; Ettler, Vojt?ch; Nyambe, Imasiku

2010-10-15

257

Evaluation of three endemic Mediterranean plant species Atriplex halimus, Medicago lupulina and Portulaca oleracea for Phytoremediation of Ni, Pb and Zn  

NASA Astrophysics Data System (ADS)

The success of phytoremediation depends upon the identification of suitable plants species that hyperaccumulate/tolerate heavy metals and produce large amounts of biomass. In this study, three endemic Mediterranean plant species Atriplex halimus, Medicago lupulina and Portulaca oleracea, were grown hydroponically to assess their potential use in phytoremediation of Ni, Pb and Zn and biomass production. The objective of this research is to improve phytoremediation procedures by searching for a new endemic Mediterranean plant species which can be used for phytoremediation of low/moderate contamination in the Mediterranean arid and semiarid conditions and bioenergy production. The hydroponics experiment was carried out in a growth chamber using half strength Hoagland's solution as control (CTR) and 5 concentrations for Pb and Zn (5, 10, 25, 50 and 100 mg L-1) and 3 concentrations for Ni (1, 2, and 5 mg L-1). Complete randomized design with five replications was adopted. Main growth parameters (shoot and root dry weight, shoot and root length and chlorophyll content) were determined. Shoots and roots were analyzed for their metals contents. Some interesting contributions of this research are: (i) plant metal uptake efficiency ranked as follows: A. halimus > M. lupulina > P. oleracea, whereas heavy metal toxicity ranked as follows: Ni > Zn > Pb, (ii) none of the plant species was identified as hyperaccumulator, (iii) Atriplex halimus and Medicago lupulina can accumulate Ni, Pb and Zn in their roots, (iv) translocate small fraction to their above ground biomass, and (v) indicate moderate pollution levels of the environment. In addition, as they are a good biomass producer, they can be used in phytostabilisation of marginal lands and their above ground biomass can be used for livestock feeding as well for bioenergy production.

Chami, Ziad Al; Amer, Nasser; Bitar, Lina Al; Mondelli, Donato; Dumontet, Stefano

2013-04-01

258

Element accumulation patterns of deciduous and evergreen tree seedlings on acid soils: implications for sensitivity to manganese toxicity.  

PubMed

Foliar nutrient imbalances, including the hyperaccumulation of manganese (Mn), are correlated with symptoms of declining health in sensitive tree species growing on acidic forest soils. The objectives of this study were to: (1) compare foliar nutrient accumulation patterns of six deciduous (sugar maple (Acer saccharum Marsh.), red maple (Acer rubrum L.), red oak (Quercus rubra L.), white oak (Quercus alba L.), black cherry (Prunus serotina Ehrh.) and white ash (Fraxinus americana L.)) and three evergreen (eastern hemlock (Tsuga canadensis L.), white pine (Pinus strobus L.) and white spruce (Picea glauca (Moench) Voss.)) tree species growing on acidic forest soils; and (2) examine how leaf phenology and other traits that distinguish evergreen and deciduous tree species influence foliar Mn accumulation rates and sensitivity to excess Mn. For the first objective, leaf samples of seedlings from five acidic, non-glaciated field sites on Pennsylvania's Allegheny Plateau were collected and analyzed for leaf element concentrations. In a second study, we examined growth and photosynthetic responses of seedlings exposed to excess Mn in sand culture. In field samples, Mn in deciduous foliage hyperaccumulated to concentrations more than twice as high as those found in evergreen needles. Among species, sugar maple was the most sensitive to excess Mn based on growth and photosynthetic measurements. Photosynthesis in red maple and red oak was also sensitive to excess Mn, whereas white oak, black cherry, white ash and the three evergreen species were tolerant of excess Mn. Among the nine species, relative rates of photosynthesis were negatively correlated with foliar Mn concentrations, suggesting that photosynthetic sensitivity to Mn is a function of its rate of accumulation in seedling foliage. PMID:15519989

St Clair, Samuel B; Lynch, Jonathan P

2005-01-01

259

Phytoremediation of Ionic and Methyl Mercury Pollution  

SciTech Connect

Phytoremediation is defined as the use of plants to extract, resist, detoxify, and/or sequester toxic environmental pollutants. The long-term goal of the proposed research is to develop and test highly productive, field-adapted plant species that have been engineered for the phytoremediation of mercury. A variety of different genes, which should enable plants to clean mercury polluted sites are being tested as tools for mercury phytoremediation, first in model laboratory plants and then in potential field species. Several of these genes have already been shown to enhance mercury phytoremediation. Mercury pollution is a serious, world-wide problem affecting the health of human and wildlife populations. Environmentally, the most serious mercury threat is the production of methylmercury (CH3Hg+) by native bacteria at mercury contaminated wetland sites. Methylmercury is inherently more toxic than metallic (Hg(0)) or ionic (Hg(II)) mercury, and because methylmercury is prolifically biomagnified up the food chain, it poses the most immediate danger to animal populations. We have successfully engineered two model plants, Arabidopsis and tobacco, to use the bacterial merB gene to convert methylmercury to less toxic ionic mercury and to use the bacterial merA gene to further detoxify ionic mercury to the least toxic form of mercury, metallic mercury. Plants expressing both MerA and MerB proteins detoxify methylmercury in two steps to the metallic form. These plants germinate, grow, and set seed at normal growth rates on levels of methylmercury or ionic mercury that are lethal to normal plants. Our newest efforts involve engineering plants with several additional bacterial and plant genes that allow for higher levels of mercury resistance and mercury hyperaccumulation. The potential for these plants to hyperaccumulate mercury was further advanced by developing constitutive, aboveground, and root-specific gene expression systems.

Meagher, Richard B.

2004-12-01

260

Fungi ingestion as an important factor influencing heavy metal intake in roe deer: evidence from faeces.  

PubMed

In nature, animals have to cope with the fluctuating bioavailable metal pool in their habitat, which results in a seasonal variability of heavy metal levels in the animal body. Indeed, a pronounced summer-autumnal peak of heavy metals in roe deer (Capreolus capreolus L.) kidney was recently found in Slovenia. Considering the well-known hyperaccumulative ability of fungi, their ingestion was hypothesised to be one of the main reasons for the peak. Although fungi as a group are known to be a seasonally important food source for roe deer, data on their composition in the nutrition of the species have been lacking. To ascertain the importance of fungi ingestion on heavy metal intake in roe deer, we simultaneously studied fungal spores (by microscopic determination) and heavy metal levels (by inductively coupled plasma mass spectrometry and atomic absorption spectrometry) in roe deer faeces, collected in the period July-November 2001 at Veliki Vrh, the Salek Valley, Slovenia. Irrespective of species, fungal spores were present in 89% of faeces; the following genera were found to be consumed by roe deer: Lycoperdon, Calvatia, Hypholoma, Coprinus, Russula, Elaphomyces, Xerocomus, Enteloma, Amanita, Cortinarius, Agaricus, Inocybe, Boletus, Macrolepiota, Suillus and Pluteus. While the importance of fungi ingestion on the seasonal variability of other metals is less clear, it doubtless influences Hg intake in roe deer, which is confirmed by: (a) the high frequency of fungi in roe deer nutrition; (b) their hyperaccumulative ability; (c) the temporal distribution of Hg in roe deer faeces; (d) differences among three classes of faeces established on the basis of the frequency of spores present; (e) the correlation between the number of fungal genera present and Hg levels in faeces. Therefore, the influence of fungi ingestion has to be taken into consideration in assessing the hazard due to the accumulation of mercury along the food-chain. PMID:15081708

Pokorny, Bostjan; Al Sayegh-Petkovsek, Samar; Ribaric-Lasnik, Cvetka; Vrtacnik, Jaroslav; Doganoc, Darinka Z; Adamic, Miha

2004-05-25

261

A chemical screen for suppressors of the avrRpm1-RPM1-dependent hypersensitive cell death response in Arabidopsis thaliana.  

PubMed

Arabidopsis thaliana RPM1 encodes an intracellular immune sensor that conditions disease resistance to Pseudomonas syringae expressing the type III effector protein AvrRpm1. Conditional expression of this type III effector in a transgenic line carrying avrRpm1 under the control of a steroid-inducible promoter results in RPM1-dependent cell death that resembles the cell death response of the incompatible RPM1-avrRpm1 plant-bacterium interaction. This line was previously used in a genetic screen, which revealed two genes that likely function in the folding of pre-activation RPM1. We established a chemical screen for small molecules that suppress steroid-inducible and RPM1-avrRpm1-dependent cell death in Arabidopsis seedlings. Screening of a library comprising 6,800 compounds of natural origin identified two trichothecene-type mycotoxins, 4,15-diacetoxyscirpenol (DAS) and neosolaniol (NEO), which are synthesized by Fusarium and other fungal species. However, protein blot analysis revealed that DAS and NEO inhibit AvrRpm1 synthesis rather than suppress RPM1-mediated responses. This inhibition of translational activity likely explains the survival of the seedlings under screening conditions. Likewise, flg22-induced defense responses are also impaired at the translational, but not the transcriptional, level by DAS or NEO. Unexpectedly, both compounds not only prevented AvrRpm1 synthesis, but rather caused an apparent hyper-accumulation of RPM1 and HSP70. The hyper-accumulation phenotype is likely unrelated to the ribotoxic function of DAS and NEO and could be due to an inhibitory activity on the proteolytic machinery of Arabidopsis or elicitor-like activities of type A trichothecenes. PMID:20140739

Serrano, Mario; Hubert, David A; Dangl, Jeffery L; Schulze-Lefert, Paul; Kombrink, Erich

2010-02-07

262

The effect of EDDS and citrate on the uptake of lead in hydroponically grown Matthiola flavida.  

PubMed

Root and shoot lead concentrations and the impact of chelating agents on these were investigated in two populations of the novel metallophyte Matthiola flavida. Plants were exposed in hydroponics to Pb(NO3)2, supplied alone, or in combination with citric acid, or EDDS. When supplied at concentrations expected to bind about 95% of the Pb in a solution containing 1-?M Pb (1000?M citrate or 3.1?M EDDS, respectively), the root and shoot Pb concentrations were dramatically lowered, in comparison with a 1-?M free ionic Pb control exposure. A 1-mM EDDS+1-?M Pb treatment decreased the plants' Pb concentrations further, even to undetectable levels in one population. At 100?M Pb in a 1-mM EDDS-amended solution the Pb concentration increased strongly in shoots, but barely in roots, in comparison with the 1-?M Pb+1-mM EDDS treatment, without causing toxicity symptoms. Further increments of the Pb concentration in the 1-mM EDDS-amended solution, i.e. to 800 and 990?M, caused Pb hyperaccumulation, both in roots and in shoots, associated with a complete arrest of root growth and foliar necrosis. M. flavida seemed to be devoid of constitutive mechanisms for uptake of Pb-citrate or Pb-EDDS complexes. Hyperaccumulation of Pb-EDDS occurred only at high exposure levels. Pb-EDDS was toxic, but is much less so than free Pb. Free EDDS did not seem to be toxic at the concentrations tested. PMID:23806486

Mohtadi, Ahmad; Ghaderian, Seyed Majid; Schat, Henk

2013-06-24

263

A Phytoremediation Strategy for Arsenic  

SciTech Connect

A Phytoremediation Strategy for Arsenic Progress Report May, 2005 Richard B. Meagher Principal Investigator Arsenic pollution affects the health of several hundred millions of people world wide, and an estimated 10 million Americans have unsafe levels of arsenic in their drinking water. However, few environmentally sound remedies for cleaning up arsenic contaminated soil and water have been proposed. Phytoremediation, the use of plants to extract and sequester environmental pollutants, is one new technology that offers an ecologically sound solution to a devastating problem. We propose that it is less disruptive to the environment to harvest and dispose of several thousand pounds per acre of contaminated aboveground plant material, than to excavate and dispose of 1 to 5 million pounds of contaminated soil per acre (assumes contamination runs 3 ft deep). Our objective is to develop a genetics-based phytoremediation strategy for arsenic removal that can be used in any plant species. This strategy requires the enhanced expression of several transgenes from diverse sources. Our working hypothesis is that organ-specific expression of several genes controlling the transport, electrochemical state, and binding of arsenic will result in the efficient extraction and hyperaccumulation of arsenic into aboveground plant tissues. This hypothesis is supported by theoretical arguments and strong preliminary data. We proposed six Specific Aims focused on testing and developing this arsenic phytoremediation strategy. During the first 18 months of the grant we made significant progress on five Specific Aims and began work on the sixth as summarized below. Specific Aim 1: Enhance plant arsenic resistance and greatly expand sinks for arsenite by expressing elevated levels of thiol-rich, arsenic-binding peptides. Hyperaccumulation of arsenic depends upon making plants that are both highly tolerant to arsenic and that have the capacity to store large amounts of arsenic aboveground. Phytochelatins bind diverse thiol-reactive elements like As(III) and are synthesized from amino acids in a three-step enzymatic pathway utilizing three enzymes: ECS = gamma-glutamylcysteine synthetase; GS = GSH synthetase; and PS = phytochelatin synthase. We cloned each of the genes that encode these enzymes and used at least two different plant promoters to express them in transgenic Arabidopsis. We have shown that all three confer significant resistance to arsenic and allow rapid growth on a concentration of arsenic (300 micromolar) that kills wild-type seeds and plants.

Meagher, Richard B.

2005-06-01

264

Timing of phosphate application affects arsenic phytoextraction by Pteris vittata L. of different ages.  

PubMed

The effects of timing in phosphate application on plant growth and arsenic removal by arsenic hyperaccumulator Pteris vittata L. of different ages were evaluated. The hydroponic experiment consisted of three plant ages (A45d, A90d and A180d) and three P feeding regimens (P200+0, P134+66 and P66+134) growing for 45 d in 0.2-strength Hoagland-Arnon solution containing 145 microg L(-1) As. While all plants received 200 microM P, P was added in two phases: during acclimation and after arsenic exposure. High initial P-supply (P200+0) favored frond biomass production and plant P uptake, while split-P application (P134+66 and P66+134) favored plant root production. Single P addition favored arsenic accumulation in the roots while split-P addition increased frond arsenic accumulation. Young ferns (A45d) in treatment P134+66 were the most efficient in arsenic removal, reducing arsenic concentration to below 10 microg L(-1) in 35 d. The results indicated that the use of young ferns, coupled with feeding of low initial P or split-P application, increased the efficiency of arsenic removal by P. vittata. PMID:18045757

Santos, Jorge A G; Gonzaga, Maria I S; Ma, Lena Q; Srivastava, M

2007-11-28

265

Accumulation and localization of cadmium in Echinochloa polystachya grown within a hydroponic system.  

PubMed

Phytoremediation is a technology for extracting or inactivating pollutants. Echinochloa polystachya [(H.B.K.) Hitchcock] (Poaceae) is a fast-growing perennial grass that is common in tropical areas and is often found in oil-polluted soils that contain high concentrations of heavy metals. However, its tolerance to heavy metals, and its ability to accumulate them, has yet to be investigated. Here we test the hypothesis that E. polystachya is able to accumulate high concentrations of cadmium (Cd). Plants were grown hydroponically with different levels of Cd(2+) (0, 0.25, 1, 2, 10, 50, and 100mgL(-1)), and were found to be tolerant to Cd(2+) at all levels. No metal-toxicity symptoms were observed at any Cd(2+) level. Root and leaves Cd concentrations were 299+/-13.93 and 233+/-8.77mgkg(-1) (on a dry weight basis), respectively. Scanning electron microscopy showed the inclusion of Cd within the xylem; this result was confirmed by energy dispersive X-ray spectrometry. Leaf tissues also accumulated Cd, especially within the bulliform cells of the epidermis. We conclude that E. polystachya is a hyperaccumulator of Cd. While data for other metals are not yet available, E. polystachya shows promise in the phytoextraction of Cd from polluted tropical sites. PMID:16920257

Solís-Domínguez, F A; González-Chávez, M C; Carrillo-González, R; Rodríguez-Vázquez, R

2006-07-14

266

Phytoremediation of heavy metals--concepts and applications.  

PubMed

The mobilization of heavy metals by man through extraction from ores and processing for different applications has led to the release of these elements into the environment. Since heavy metals are nonbiodegradable, they accumulate in the environment and subsequently contaminate the food chain. This contamination poses a risk to environmental and human health. Some heavy metals are carcinogenic, mutagenic, teratogenic and endocrine disruptors while others cause neurological and behavioral changes especially in children. Thus remediation of heavy metal pollution deserves due attention. Different physical and chemical methods used for this purpose suffer from serious limitations like high cost, intensive labor, alteration of soil properties and disturbance of soil native microflora. In contrast, phytoremediation is a better solution to the problem. Phytoremediation is the use of plants and associated soil microbes to reduce the concentrations or toxic effects of contaminants in the environments. It is a relatively recent technology and is perceived as cost-effective, efficient, novel, eco-friendly, and solar-driven technology with good public acceptance. Phytoremediation is an area of active current research. New efficient metal hyperaccumulators are being explored for applications in phytoremediation and phytomining. Molecular tools are being used to better understand the mechanisms of metal uptake, translocation, sequestration and tolerance in plants. This review article comprehensively discusses the background, concepts and future trends in phytoremediation of heavy metals. PMID:23466085

Ali, Hazrat; Khan, Ezzat; Sajad, Muhammad Anwar

2013-03-07

267

Functional analysis of metals distribution in organs of the beetle Chrysolina pardalina exposed to excess of nickel by Micro-PIXE  

NASA Astrophysics Data System (ADS)

Micro-PIXE mapping of elemental distribution within organs of Chrysolina pardalina beetle feeding on a nickel hyperaccumulating plant species Berkheya coddii, was used to check its ability to cope with excess of nickel and to study quantitative and qualitative relations between nickel and other elements in physiologically important structures. Data analysis was performed using a new PC based version of the GeoPIXE software (GeoPIXE II). The use of micro-PIXE, supported with analysis of electronograms demonstrated mechanism of Ni rejection from the insects' body. Concretions rich in Zn, Cu, Fe, Mn, Br are formed in Malpighian tubules and in the midgut cells. Organs important for maintaining homeostasis are protected against excess of metals. Malpighian tubules play a crucial role in Ni elimination from hemolymph, further rejected through the digestive tract and in larve also with exuvia during molting. Both used methods proved that midgut cells in adults could regenerate. Such an adaptive mechanism has not been earlier described in adult beetles.

Przybylowicz, W. J.; Mesjasz Przybylowicz, J.; Migula, P.; Glowacka, E.; Nakonieczny, M.; Augustyniak, M.

2003-09-01

268

Comparative performance of trace element bioaccumulation and biomonitoring in the plant species Typha domingensis, Phragmites australis and Arundo donax.  

PubMed

Toxic levels of trace elements in the environment have been reported worldwide over the last few decades, and their increasing concentrations are of the utmost concern because of the adverse effects on human life and ecosystems. Several plant species are able to accumulate trace elements, and may be used for monitoring and remediation of polluted sites. This study compared the capacity of trace element bioaccumulation in three wetland plants distributed worldwide: Typha domingensis, Phragmites australis and Arundo donax. The aims were to identify which species show better potential for removal and monitoring of these elements: Al, As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn. Results showed that all species may be used as biomonitors of trace element contamination in sediment, but only P. australis and A. donax showed also a correlation with water. Overall, T. domingensis and P. australis showed a greater capacity of bioaccumulation as well as a greater efficiency of element removal than A. donax. In particular, T. domingensis and P. australis may be used for Hg phytostabilization, the former acted also as a hyperaccumulator for Hg phytoextraction and as a promising species for As phytostabilization. In contaminated wetlands, the presence of T. domingensis and P. australis may increase the general retention of trace elements, thus, their introduction is recommended for possible actions of phytoremediation and biomonitoring. PMID:23932595

Bonanno, Giuseppe

2013-08-07

269

Responses of Noccaea caerulescens and Lupinus albus in trace elements-contaminated soils.  

PubMed

Plants exposed to trace elements can suffer from oxidative stress, which is characterised by the accumulation of reactive oxygen species, alteration in the cellular antioxidant defence system and ultimately lipid peroxidation. We assessed the most-appropriate stress indexes to describe the response of two plant species, with different strategies for coping with trace elements (TEs), to particular contaminants. Noccaea caerulescens, a hyperaccumulator, and Lupinus albus, an excluder, were grown in three soils of differing pH: an acidic soil, a neutral soil (both contaminated mainly by Cu, Zn and As) and a control soil. Then, plant stress indicators were measured. As expected, N. caerulescens accumulated higher levels of Zn and Cd in shoots than L. albus, this effect being stronger in the acid soil, reflecting greater TE solubility in this soil. However, the shoot concentrations of Mn were higher in L. albus than in N. caerulescens, while the As concentration was similar in the two species. In L. albus, the phenolic content and lipid peroxidation were related with the Cu concentration, whereas the Zn and Cd concentrations in N. caerulescens were more closely related to glutathione content and lipid peroxidation. Interestingly, phytochelatins were only found in L. albus grown in polluted soils. Hence, the two species differed with respect to the TEs which provoked stress and the biochemical indicators of the stress, there being a close relationship between the accumulation of TEs and their associated stress indicators in the different plant organs. PMID:23466747

Martínez-Alcalá, Isabel; Hernández, Luis E; Esteban, Elvira; Walker, David J; Bernal, M Pilar

2013-02-12

270

Proteomic analysis of Mn-induced resistance to powdery mildew in grapevine.  

PubMed

Previous studies documented that metal hyperaccumulation armours plants with direct defences against pathogens. In the present study, it was found that high leaf Mn concentrations (<2500 µg g(-1)) induced grapevine resistance to powdery mildew [Uncinula necator (Schw.) Burr]. Manganese delayed pathogen spreading after powdery mildew (PM) inoculation, but did not directly inhibit pathogen growth on a long-term basis. It was postulated that the grapevine resistance resulted from the induction of protective mechanisms in planta. To test this hypothesis, the proteome profile was analysed by Difference Gel Electrophoresis (DIGE) methods to identify proteins that are putatively involved in pathogen resistance. A high Mn concentration caused little oxidative pressure in grapevine, but oxidative stress was deeply enhanced by PM stress. Except for a few proteins that were related to oxidative pressure and proteins specially regulated by Mn or PM, most of the detected proteins exhibited similar changes under excess Mn stress and under PM stress, suggesting that similar signalling processes mediate the responses to the two stresses. As well as PM stress, high leaf Mn concentration significantly enhanced salicylic acid concentration and increased the expression of proteins involved in ethylene and jasmonic acid synthesis. The proteins related to pathogen resistance were also enhanced by excess Mn, including a PR-like protein, an NBS-LRR analogue, and a JOSL protein, and this was accompanied by the increased activity of phenylalanine ammonia lyase. It was concluded that high leaf Mn concentration triggered protective mechanisms against pathogens in grapevine. PMID:22936830

Yao, Yin An; Wang, Junru; Ma, XueMei; Lutts, Stanley; Sun, Chuanchuan; Ma, Jinbiao; Yang, Yongqing; Achal, Varenyam; Xu, Gang

2012-09-01

271

Extensive variation in cadmium tolerance and accumulation among populations of Chamaecrista fasciculata.  

PubMed

Plant populations may vary substantially in their tolerance for and accumulation of heavy metals, and assessment of this variability is important when selecting species to use in restoration or phytoremediation projects. We examined the population variation in cadmium tolerance and accumulation in a leguminous pioneer species native to the eastern United States, the partridge pea (Chamaecrista fasciculata). We assayed growth, reproduction and patterns of cadmium accumulation in six populations of C. fasciculata grown on a range of cadmium-contaminated soils. In general, C. fasciculata exhibited tolerance in low to moderate soil cadmium concentrations. Both tolerance and accumulation patterns varied across populations. C. fasciculata exhibited many characteristics of a hyperaccumulator species, with high cadmium uptake in shoots and roots. However, cadmium was excluded from extrafloral nectar. As a legume with tolerance for moderate cadmium contamination, C. fasciculata has potential for phytoremediation. However, our findings also indicate the importance of considering the effects of genetic variation on plant performance when screening plant populations for utilization in remediation and restoration activities. Also, there is potential for cadmium contamination to affect other species through contamination of leaves, fruits, flowers, pollen and root nodules. PMID:23667586

Henson, Tessa M; Cory, Wendy; Rutter, Matthew T

2013-05-07

272

Muscle length and myonuclear position are independently regulated by distinct Dynein pathways  

PubMed Central

Various muscle diseases present with aberrant muscle cell morphologies characterized by smaller myofibers with mispositioned nuclei. The mechanisms that normally control these processes, whether they are linked, and their contribution to muscle weakness in disease, are not known. We examined the role of Dynein and Dynein-interacting proteins during Drosophila muscle development and found that several factors, including Dynein heavy chain, Dynein light chain and Partner of inscuteable, contribute to the regulation of both muscle length and myonuclear positioning. However, Lis1 contributes only to Dynein-dependent muscle length determination, whereas CLIP-190 and Glued contribute only to Dynein-dependent myonuclear positioning. Mechanistically, microtubule density at muscle poles is decreased in CLIP-190 mutants, suggesting that microtubule-cortex interactions facilitate myonuclear positioning. In Lis1 mutants, Dynein hyperaccumulates at the muscle poles with a sharper localization pattern, suggesting that retrograde trafficking contributes to muscle length. Both Lis1 and CLIP-190 act downstream of Dynein accumulation at the cortex, suggesting that they specify Dynein function within a single location. Finally, defects in muscle length or myonuclear positioning correlate with impaired muscle function in vivo, suggesting that both processes are essential for muscle function.

Folker, Eric S.; Schulman, Victoria K.; Baylies, Mary K.

2012-01-01

273

Compromised virus-induced gene silencing in RDR6-deficient plants.  

PubMed

RNA silencing in plants serves as a potent antiviral defense mechanism through the action of small interfering RNAs (siRNAs), which direct RNA degradation. siRNAs can be derived directly from the viral genome or via the action of host-encoded RNA-dependent RNA polymerases (RDRs). Plant genomes encode multiple RDRs, and it has been demonstrated that plants defective for RDR6 hyperaccumulate several classes of virus. In this study, we compared the effectiveness of virus-induced gene silencing (VIGS) and RNA-directed DNA methylation (RdDM) in wild-type and RDR6-deficient Nicotiana benthamiana plants. For the potexvirus Potato virus X (PVX) and the potyvirus Plum pox virus (PPV), the efficiency of both VIGS and RdDM were compromised in RDR6-defective plants despite accumulating high levels of viral siRNAs similar to infection of wild-type plants. The reduced efficiency of VIGS and RdDM was unrelated to the size class of siRNA produced and, at least for PVX, was not dependent on the presence of the virus-encoded silencing suppressor protein, 25K. We suggest that primary siRNAs produced from PVX and PPV in the absence of RDR6 may not be good effectors of silencing and that RDR6 is required to produce secondary siRNAs that drive a more effective antiviral response. PMID:19129420

Vaistij, Fabián E; Jones, Louise

2009-01-07

274

Ctr1 transports silver into mammalian cells.  

PubMed

Silver is a non-essential, toxic metal. The use of silver as an antimicrobial agent in many applications and its presence as a contaminant in foods and air can lead to accumulation in tissues. Despite its widespread use, the systems involved in the uptake of silver into mammalian cells are presently unknown. Previous studies have shown that copper uptake at the plasma membrane by copper transporter 1 (Ctr1) is inhibited by an excess of silver, suggesting that Ctr1 may function in importing silver into cells. In this study we examined directly the role of Ctr1 in the accumulation of silver in mammalian cells using over-expression experiments and mouse embryonic fibroblast cells lacking Ctr1. COS-7 cells transfected to express a human Ctr1-green fluorescent protein (hCtr1-GFP) fusion protein hyper-accumulated silver when incubated in medium supplemented with low micromolar concentrations (2.5-10 micromol/L) of AgNO(3). An hCtr1-GFPM150L,M154L variant deficient for copper transport failed to stimulate accumulation of silver. Mouse embryonic fibroblast cells lacking Ctr1 showed approximately a 50% reduction in silver content when incubated in silver-supplemented medium compared to a wild-type isogenic cell line. Collectively, these data demonstrate that Ctr1 transports both copper and silver and suggest that Ctr1 is an important transport protein in the accumulation of silver in mammalian cells. PMID:20569931

Bertinato, Jesse; Cheung, Lawrence; Hoque, Rezaul; Plouffe, Louise J

2010-02-12

275

Imaging of metal bioaccumulation in hay-scented fern (Dennstaedtia punctilobula) rhizomes growing on contaminated soils by laser ablation ICP-MS.  

PubMed

Understanding Pb removal from the translocation stream is vital to engineering Pb hyperaccumulation in above ground organs, which would enhance the economic feasibility of Pb phytoextraction technologies. We investigated Cu, Pb, Sb and Zn distributions in Hay-scented fern (Dennstaedtia punctilobula) rhizomes on shooting range soils by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), analyzing digested rhizomes, stems, and fronds using ICP-MS. Nutrients Cu and Zn concentrated in fronds while toxic elements Pb and Sb did not, showing potential Pb and Sb sequestration in the rhizome. Frond and rhizome concentration of Pb was 0.17 ± 0.10% and 0.32 ± 0.21% of dry biomass, respectively. The 208Pb/13C and 121Sb/13C determined by LA-ICP-MS increased from inner sclerotic cortex to the epidermis, while Pb concentrated in the starchy cortex only in contaminated sites. These results suggest that concentration dependent bioaccumulation in the rhizome outer cortex removes Pb from the vascular transport stream. PMID:22595761

Koelmel, Jeremy; Amarasiriwardena, Dulasiri

2012-05-15

276

Potential phytoextraction and phytostabilization of perennial peanut on copper-contaminated vineyard soils and copper mining waste.  

PubMed

This study sought to evaluate the potential of perennial peanut (Arachis pintoi) for copper phytoremediation in vineyard soils (Inceptisol and Mollisol) contaminated with copper and copper mining waste. Our results showed high phytomass production of perennial peanut in both vineyard soils. Macronutrient uptakes were not negatively affected by perennial peanut cultivated in all contaminated soils. Plants cultivated in Mollisol showed high copper concentrations in the roots and shoots of 475 and 52 mg kg(-1), respectively. Perennial peanut plants showed low translocation factor values for Cu, although these plants showed high bioaccumulation factor (BCF) for both vineyard soils, Inceptisol and Mollisol, with BCF values of 3.83 and 3.24, respectively, being characterized as a copper hyperaccumulator plant in these soils. Copper phytoextraction from Inceptisol soil was the highest for both roots and entire plant biomass, with more than 800 mg kg(-1) of copper in whole plant. The highest potential copper phytoextraction by perennial peanut was in Inceptisol soil with copper removal of 2,500 g ha(-1). Also, perennial peanut showed high potential for copper phytoremoval in copper mining waste and Mollisol with 1,700 and 1,500 g of copper per hectare, respectively. In addition, perennial peanuts characterized high potential for phytoextraction and phytostabilization of copper in vineyard soils and copper mining waste. PMID:21286847

Andreazza, Robson; Bortolon, Leandro; Pieniz, Simone; Giacometti, Marcelo; Roehrs, Dione D; Lambais, Mácio R; Camargo, Flávio A O

2011-02-01

277

Irrigation of three wetland species and a hyperaccumlating fern with arsenic-laden solutions: observations of growth, arsenic uptake, nutrient status, and chlorophyll content.  

PubMed

Engineered wetlands can be an integral part of a treatment strategy for remediating arsenic-contaminated wastewater, wherein, As is removed by adsorption to soil particles, chemical transformation, precipitation, or accumulation by plants. The remediation process could be optimized by choosing plant species that take up As throughout the seasonal growing period. This report details experiments that utilize wetland plant species native to Ohio (Carex stricta, Pycnanthemum virginianum, and Spartina pectinata) that exhibit seasonally related maximal growth rates, plus one hyperaccumulating fern (Pteris vittata) that was used to compare arsenic tolerance. All plants were irrigated with control or As-laden nutrient solutions (either 0, 1.5, or 25 mg As L(-1)) for 52 d. Biomass, nutrient content, and chlorophyll content were compared between plants treated and control plants (n = 5). At the higher concentration of arsenic (25 mg L(-1)), plant biomass, leaf area, and total chlorophyll were all lower than values in control plants. A tolerance index, based on total plant biomass at the end of the experiment, indicated C. stricta (0.99) and S. pectinata (0.84) were more tolerant than the other plant species when irrigated with 1.5 mg As L(-1). These plant species can be considered as candidates for engineered wetlands. PMID:23819297

Rofkar, Jordan R; Dwyer, Daryl F

2013-01-01

278

The CRR1 Nutritional Copper Sensor in Chlamydomonas Contains Two Distinct Metal-Responsive Domains[C][W][OA  

PubMed Central

Copper response regulator 1 (CRR1), an SBP-domain transcription factor, is a global regulator of nutritional copper signaling in Chlamydomonas reinhardtii and activates genes necessary during periods of copper deficiency. We localized Chlamydomonas CRR1 to the nucleus in mustard (Sinapis alba) seedlings, a location consistent with its function as a transcription factor. The Zn binding SBP domain of CRR1 binds copper ions in vitro. Cu(I) can replace Zn(II), but the Cu(II) form is unstable. The DNA binding activity is inhibited in vitro by Cu(II) or Hg(II) ions, which also prevent activation of transcription in vivo, but not by Co(II) or Ni(II), which have no effect in vivo. Copper inhibition of DNA binding is reduced by mutation of a conserved His residue. These results implicate the SBP domain in copper sensing. Deletion of a C-terminal metallothionein-like Cys-rich domain impacted neither nutritional copper signaling nor the effect of mercuric supplementation, but rendered CRR1 insensitive to hypoxia and to nickel supplementation, which normally activate the copper deficiency regulon in wild-type cells. Strains carrying the crr1-?Cys allele upregulate ZRT genes and hyperaccumulate Zn(II), suggesting that the effect of nickel ions may be revealing a role for the C-terminal domain of CRR1 in zinc homeostasis in Chlamydomonas.

Sommer, Frederik; Kropat, Janette; Malasarn, Davin; Grossoehme, Nicholas E.; Chen, Xiaohua; Giedroc, David P.; Merchant, Sabeeha S.

2010-01-01

279

Arsenic tolerance, uptake, and accumulation by nonmetallicolous and metallicolous populations of Pteris vittata L.  

PubMed

Although it is known that the first As hyperaccumulator identified, Pteris vittata L., could exist in As-contaminated as well as uncontaminated soils, intra-specific variation in As accumulation among metallicolous (from As-contaminated soils) and nonmetallicolous populations (from uncontaminated soils) of P. vittata has not been fully explored. Variations in As concentrations of fronds were observed in three nonmetallicolous populations and four metallicolous populations of P. vittata collected from southeast China. The kinetics study showed that the concentration-dependent influx of arsenate and arsenite observed followed Michaelis-Menten kinetics, and that the average V max for arsenate and arsenite was apparently larger in the three nonmetallicolous populations than that in the three metallicolous populations. The pot trials indicated that the nonmetallicolous populations had significantly (p?

Wu, Fuyong; Deng, Dan; Wu, Shengchun; Lin, Xiangui; Wong, Ming Hung

2013-03-14

280

Arsenic and Antimony Transporters in Eukaryotes  

PubMed Central

Arsenic and antimony are toxic metalloids, naturally present in the environment and all organisms have developed pathways for their detoxification. The most effective metalloid tolerance systems in eukaryotes include downregulation of metalloid uptake, efflux out of the cell, and complexation with phytochelatin or glutathione followed by sequestration into the vacuole. Understanding of arsenic and antimony transport system is of high importance due to the increasing usage of arsenic-based drugs in the treatment of certain types of cancer and diseases caused by protozoan parasites as well as for the development of bio- and phytoremediation strategies for metalloid polluted areas. However, in contrast to prokaryotes, the knowledge about specific transporters of arsenic and antimony and the mechanisms of metalloid transport in eukaryotes has been very limited for a long time. Here, we review the recent advances in understanding of arsenic and antimony transport pathways in eukaryotes, including a dual role of aquaglyceroporins in uptake and efflux of metalloids, elucidation of arsenic transport mechanism by the yeast Acr3 transporter and its role in arsenic hyperaccumulation in ferns, identification of vacuolar transporters of arsenic-phytochelatin complexes in plants and forms of arsenic substrates recognized by mammalian ABC transporters.

Maciaszczyk-Dziubinska, Ewa; Wawrzycka, Donata; Wysocki, Robert

2012-01-01

281

Muscle length and myonuclear position are independently regulated by distinct Dynein pathways.  

PubMed

Various muscle diseases present with aberrant muscle cell morphologies characterized by smaller myofibers with mispositioned nuclei. The mechanisms that normally control these processes, whether they are linked, and their contribution to muscle weakness in disease, are not known. We examined the role of Dynein and Dynein-interacting proteins during Drosophila muscle development and found that several factors, including Dynein heavy chain, Dynein light chain and Partner of inscuteable, contribute to the regulation of both muscle length and myonuclear positioning. However, Lis1 contributes only to Dynein-dependent muscle length determination, whereas CLIP-190 and Glued contribute only to Dynein-dependent myonuclear positioning. Mechanistically, microtubule density at muscle poles is decreased in CLIP-190 mutants, suggesting that microtubule-cortex interactions facilitate myonuclear positioning. In Lis1 mutants, Dynein hyperaccumulates at the muscle poles with a sharper localization pattern, suggesting that retrograde trafficking contributes to muscle length. Both Lis1 and CLIP-190 act downstream of Dynein accumulation at the cortex, suggesting that they specify Dynein function within a single location. Finally, defects in muscle length or myonuclear positioning correlate with impaired muscle function in vivo, suggesting that both processes are essential for muscle function. PMID:22951643

Folker, Eric S; Schulman, Victoria K; Baylies, Mary K

2012-09-05

282

Stable Transformation of Ferns Using Spores as Targets: Pteris vittata and Ceratopteris thalictroides.  

PubMed

Ferns (Pteridophyta) are very important members of the plant kingdom that lag behind other taxa with regards to our understanding of their genetics, genomics, and molecular biology. We report here, to our knowledge, the first instance of stable transformation of fern with recovery of transgenic sporophytes. Spores of the arsenic hyperaccumulating fern Pteris vittata and tetraploid 'C-fern Express' (Ceratopteris thalictroides) were stably transformed by Agrobacterium tumefaciens with constructs containing the P. vittata actin promoter driving a GUSPlus reporter gene. Reporter gene expression assays were performed on multiple tissues and growth stages of gametophytes and sporophytes. Southern-blot analysis confirmed stable transgene integration in recovered sporophytes and also confirmed that no plasmid from A. tumefaciens was present in the sporophyte tissues. We recovered seven independent transformants of P. vittata and four independent C. thalictroides transgenics. Inheritance analyses using ?-glucuronidase (GUS) histochemical staining revealed that the GUS transgene was stably expressed in second generation C. thalictroides sporophytic tissues. In an independent experiment, the gusA gene that was driven by the 2× Cauliflower mosaic virus 35S promoter was bombarded into P. vittata spores using biolistics, in which putatively stable transgenic gametophytes were recovered. Transformation procedures required no tissue culture or selectable marker genes. However, we did attempt to use hygromycin selection, which was ineffective for recovering transgenic ferns. This simple stable transformation method should help facilitate functional genomics studies in ferns. PMID:23933990

Muthukumar, Balasubramaniam; Joyce, Blake L; Elless, Mark P; Stewart, C Neal

2013-08-09

283

Pho85p, a cyclin-dependent protein kinase, and the Snf1p protein kinase act antagonistically to control glycogen accumulation in Saccharomyces cerevisiae.  

PubMed Central

In Saccharomyces cerevisiae, nutrient levels control multiple cellular processes. Cells lacking the SNF1 gene cannot express glucose-repressible genes and do not accumulate the storage polysaccharide glycogen. The impaired glycogen synthesis is due to maintenance of glycogen synthase in a hyperphosphorylated, inactive state. In a screen for second site suppressors of the glycogen storage defect of snf1 cells, we identified a mutant gene that restored glycogen accumulation and which was allelic with PHO85, which encodes a member of the cyclin-dependent kinase family. In cells with disrupted PHO85 genes, we observed hyperaccumulation of glycogen, activation of glycogen synthase, and impaired glycogen synthase kinase activity. In snf1 cells, glycogen synthase kinase activity was elevated. Partial purification of glycogen synthase kinase activity from yeast extracts resulted in the separation of two fractions by phenyl-Sepharose chromatography, both of which phosphorylated and inactivated glycogen synthase. The activity of one of these, GPK2, was inhibited by olomoucine, which potently inhibits cyclin-dependent protein kinases, and contained an approximately 36-kDa species that reacted with antibodies to Pho85p. Analysis of Ser-to-Ala mutations at the three potential Gsy2p phosphorylation sites in pho85 cells implicated Ser-654 and/or Thr-667 in PHO85 control of glycogen synthase. We propose that Pho85p is a physiological glycogen synthase kinase, possibly acting downstream of Snf1p.

Huang, D; Farkas, I; Roach, P J

1996-01-01

284

Recent developments in microtomography at GeoSoilEnviroCARS  

SciTech Connect

A facility for x-ray computed microtomography (CMT) is operating as a national user facility for earth and environmental sciences research on the bending magnet beamline at the GeoSoilEnviroCARS sector at the Advanced Photon Source (APS). The APS bending magnet has a critical energy of 20 keV, and thus provides high flux at photon energies up to 100 keV, making it well suited to imaging a wide range of earth materials up to several cm in size. The beamline is equipped with a Si (111) double-crystal monochromator covering the energy range from 5 to 70 keV with beam sizes up to 50mm wide and 6mm high. The transmitted x-rays are imaged with a single crystal YAG or CdWO{sub 4} scintillator, a microscope objective and a 1300 x 1030 pixel 12-bit 5MHz CCD detector. The maximum spatial resolution is under 1.5 {micro}m in both the transmission radiographs and the reconstructed slices. Data collection times for full 3-D datasets range from 5-60 minutes. This facility has been used for a wide range of studies, including multiphase fluids in porous media, high-pressure studies, meteorites, and hyper-accumulating plants. We present recent technical improvements in the system, which include improved optics for samples larger than 5mm, significant reduction of ring artifacts, and correction of mechanical errors in the rotation stage.

Rivers, M.L.; Wang, Y. (UC); (UC)

2008-08-04

285

RanGAP2 mediates nucleocytoplasmic partitioning of the NB-LRR immune receptor Rx in the Solanaceae, thereby dictating Rx function.  

PubMed

The potato (Solanum tuberosum) nucleotide binding-leucine-rich repeat immune receptor Rx confers resistance to Potato virus X (PVX) and requires Ran GTPase-activating protein 2 (RanGAP2) for effective immune signaling. Although Rx does not contain a discernible nuclear localization signal, the protein localizes to both the cytoplasm and nucleus in Nicotiana benthamiana. Transient coexpression of Rx and cytoplasmically localized RanGAP2 sequesters Rx in the cytoplasm. This relocation of the immune receptor appeared to be mediated by the physical interaction between Rx and RanGAP2 and was independent of the concomitant increased GAP activity. Coexpression with RanGAP2 also potentiates Rx-mediated immune signaling, leading to a hypersensitive response (HR) and enhanced resistance to PVX. Besides sequestration, RanGAP2 also stabilizes Rx, a process that likely contributes to enhanced defense signaling. Strikingly, coexpression of Rx with the Rx-interacting WPP domain of RanGAP2 fused to a nuclear localization signal leads to hyperaccumulation of both the WPP domain and Rx in the nucleus. As a consequence, both Rx-mediated resistance to PVX and the HR induced by auto-active Rx mutants are significantly suppressed. These data show that a balanced nucleocytoplasmic partitioning of Rx is required for proper regulation of defense signaling. Furthermore, our data indicate that RanGAP2 regulates this partitioning by serving as a cytoplasmic retention factor for Rx. PMID:21169509

Tameling, Wladimir I L; Nooijen, Claudia; Ludwig, Nora; Boter, Marta; Slootweg, Erik; Goverse, Aska; Shirasu, Ken; Joosten, Matthieu H A J

2010-12-17

286

The CRR1 nutritional copper sensor in Chlamydomonas contains two distinct metal-responsive domains.  

PubMed

Copper response regulator 1 (CRR1), an SBP-domain transcription factor, is a global regulator of nutritional copper signaling in Chlamydomonas reinhardtii and activates genes necessary during periods of copper deficiency. We localized Chlamydomonas CRR1 to the nucleus in mustard (Sinapis alba) seedlings, a location consistent with its function as a transcription factor. The Zn binding SBP domain of CRR1 binds copper ions in vitro. Cu(I) can replace Zn(II), but the Cu(II) form is unstable. The DNA binding activity is inhibited in vitro by Cu(II) or Hg(II) ions, which also prevent activation of transcription in vivo, but not by Co(II) or Ni(II), which have no effect in vivo. Copper inhibition of DNA binding is reduced by mutation of a conserved His residue. These results implicate the SBP domain in copper sensing. Deletion of a C-terminal metallothionein-like Cys-rich domain impacted neither nutritional copper signaling nor the effect of mercuric supplementation, but rendered CRR1 insensitive to hypoxia and to nickel supplementation, which normally activate the copper deficiency regulon in wild-type cells. Strains carrying the crr1-?Cys allele upregulate ZRT genes and hyperaccumulate Zn(II), suggesting that the effect of nickel ions may be revealing a role for the C-terminal domain of CRR1 in zinc homeostasis in Chlamydomonas. PMID:21131558

Sommer, Frederik; Kropat, Janette; Malasarn, Davin; Grossoehme, Nicholas E; Chen, Xiaohua; Giedroc, David P; Merchant, Sabeeha S

2010-12-03

287

Sphingoid bases and the serine catabolic enzyme CHA1 define a novel feedforward/feedback mechanism in the response to serine availability.  

PubMed

Targets of bioactive sphingolipids in Saccharomyces cerevisiae were previously identified using microarray experiments focused on sphingolipid-dependent responses to heat stress. One of these heat-induced genes is the serine deamidase/dehydratase Cha1 known to be regulated by increased serine availability. This study investigated the hypothesis that sphingolipids may mediate the induction of Cha1 in response to serine availability. The results showed that inhibition of de novo synthesis of sphingolipids, pharmacologically or genetically, prevented the induction of Cha1 in response to increased serine availability. Additional studies implicated the sphingoid bases phytosphingosine and dihydrosphingosine as the likely mediators of Cha1 up-regulation. The yeast protein kinases Pkh1 and Pkh2, known sphingoid base effectors, were found to mediate CHA1 up-regulation via the transcription factor Cha4. Because the results disclosed a role for sphingolipids in negative feedback regulation of serine metabolism, we investigated the effects of disrupting this mechanism on sphingolipid levels and on cell growth. Intriguingly, exposure of the cha1? strain to high serine resulted in hyperaccumulation of endogenous serine and in turn a significant accumulation of sphingoid bases and ceramides. Under these conditions, the cha1? strain displayed a significant growth defect that was sphingolipid-dependent. Together, this work reveals a feedforward/feedback loop whereby the sphingoid bases serve as sensors of serine availability and mediate up-regulation of Cha1 in response to serine availability, which in turn regulates sphingolipid levels by limiting serine accumulation. PMID:22277656

Montefusco, David J; Newcomb, Benjamin; Gandy, Jason L; Brice, Sarah E; Matmati, Nabil; Cowart, L Ashley; Hannun, Yusuf A

2012-01-25

288

[Hormesis effect of cadmium on Lonicera japonica].  

PubMed

A hydroponic experiment was conducted to study the growth characteristics of Lonicera japonica under the stress of different concentrations (0, 0.5, 2.5, 5, 10, and 25 mg L-1 ) cadmium (Cd), aimed to explore the hormesis effect of low concentrations Cd on L. japonica. At < or =5 mg L-1 of Cd, the maximum root length, plant dry biomass, and the contents of chlorophyll a, chlorophyll b, and carotenoid of L. japonica increased significantly, with the increment being 13. 6%, 11.7%, 14. 0% ,10. 8%, and 54. 5%, respectively, as compared with the control. <5 mg L-1 of Cd also had a definite positive effect on the leaf water content. At> or = 10 mg L-1 of Cd, the growth of L. japonica was inhibited significantly. When exposed to 25 mg L-1 of Cd, the shoot Cd concentration of L. japonica reached 622. 93 mg kg-1 , suggesting that L. japonica had a strong capacity of Cd-hyperaccumulation. The dose range of the hormesis effect of Cd on L. japonica was 0.5-5 mg L-1 of Cd. PMID:23898648

Jia, Lian; Liu, Zhou-Li; Chen, Wei; H E, Xing-Yuan; Q I, Dan

2013-04-01

289

Enhancement of heavy metal phytoremediation by Alnus firma with endophytic Bacillus thuringiensis GDB-1.  

PubMed

Phytoremediation shows potential for remediating mine tailing sites contaminated with heavy metals. Our aim was to isolate, characterize, and assess the potential of endophytic bacteria to enhance growth and metal accumulation by the hyperaccumulator Alnus firma. A bacterial strain isolated from roots of Pinus sylvestris had the capacity to remove heavy metals from mine tailing and was identified as Bacillus thuringiensis GDB-1 based on 16S ribosomal DNA sequencing. GDB-1 exhibited plant growth-promoting traits, including 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, indole acetic acid (IAA) and siderophore production, and P solubilization. The efficiency of GDB-1 to remove heavy metals was influenced by pH and initial metal concentration. Removal capacity (mg/l) was 77% for Pb (100), 64% for Zn (50), 34% for As (50), 9% for Cd (10), 8% for Cu (10), and 8% for Ni (10) during the active growth cycle in heavy metal-amended, mine tailing extract medium. Inoculating soil with GDB-1 significantly increased biomass, chlorophyll content, nodule number, and heavy metal (As, Cu, Pb, Ni, and Zn) accumulation in A. firma seedlings. Results indicate that inoculating the native plant A. firma with B. thuringiensis GDB-1 improves its efficiency for phytoremediation of soil containing mine tailings contaminated with heavy metals. PMID:23500429

Babu, A Giridhar; Kim, Jong-Dae; Oh, Byung-Taek

2013-02-18

290

Aquatic arsenic: phytoremediation using floating macrophytes.  

PubMed

Phytoremediation, a plant based green technology, has received increasing attention after the discovery of hyperaccumulating plants which are able to accumulate, translocate, and concentrate high amount of certain toxic elements in their above-ground/harvestable parts. Phytoremediation includes several processes namely, phytoextraction, phytodegradation, rhizofiltration, phytostabilization and phytovolatilization. Both terrestrial and aquatic plants have been tested to remediate contaminated soils and waters, respectively. A number of aquatic plant species have been investigated for the remediation of toxic contaminants such as As, Zn, Cd, Cu, Pb, Cr, Hg, etc. Arsenic, one of the deadly toxic elements, is widely distributed in the aquatic systems as a result of mineral dissolution from volcanic or sedimentary rocks as well as from the dilution of geothermal waters. In addition, the agricultural and industrial effluent discharges are also considered for arsenic contamination in natural waters. Some aquatic plants have been reported to accumulate high level of arsenic from contaminated water. Water hyacinth (Eichhornia crassipes), duckweeds (Lemna gibba, Lemna minor, Spirodela polyrhiza), water spinach (Ipomoea aquatica), water ferns (Azolla caroliniana, Azolla filiculoides, and Azolla pinnata), water cabbage (Pistia stratiotes), hydrilla (Hydrilla verticillata) and watercress (Lepidium sativum) have been studied to investigate their arsenic uptake ability and mechanisms, and to evaluate their potential in phytoremediation technology. It has been suggested that the aquatic macrophytes would be potential for arsenic phytoremediation, and this paper reviews up to date knowledge on arsenic phytoremediation by common aquatic macrophytes. PMID:21435676

Rahman, M Azizur; Hasegawa, H

2011-03-23

291

Compatible solute accumulation and stress-mitigating effects in barley genotypes contrasting in their salt tolerance.  

PubMed

The accumulation of compatible solutes is often regarded as a basic strategy for the protection and survival of plants under abiotic stress conditions, including both salinity and oxidative stress. In this work, a possible causal link between the ability of contrasting barley genotypes to accumulate/synthesize compatible solutes and their salinity stress tolerance was investigated. The impact of H(2)O(2) (one of the components of salt stress) on K(+) flux (a measure of stress 'severity') and the mitigating effects of glycine betaine and proline on NaCl-induced K(+) efflux were found to be significantly higher in salt-sensitive barley genotypes. At the same time, a 2-fold higher accumulation of leaf and root proline and leaf glycine betaine was found in salt-sensitive cultivars. The total amino acid content was also less affected by salinity in salt-tolerant cultivars. In these, potassium was found to be the main contributor to cytoplasmic osmolality, while in salt-sensitive genotypes, glycine betaine and proline contributed substantially to cell osmolality, compensating for reduced cytosolic K(+). Significant negative correlations (r= -0.89 and -0.94) were observed between Na(+)-induced K(+) efflux (an indicator of salt tolerance) and leaf glycine betaine and proline. These results indicate that hyperaccumulation of known major compatible solutes in barley does not appear to play a major role in salt-tolerance, but rather, may be a symptom of salt-susceptibility. PMID:18182428

Chen, Zhonghua; Cuin, Tracey A; Zhou, Meixue; Twomey, Amanda; Naidu, Bodapati P; Shabala, Sergey

2007-01-01

292

Zinc and/or cadmium accumulation in Gynura pseudochina (L.) DC. studied in vitro and the effect on crude protein  

NASA Astrophysics Data System (ADS)

Gynura pseudochina (L.) DC. is a zinc (Zn)/cadmium (Cd) hyperaccumulative plant. The aim of this study was to examine the tolerance of G. pseudochina (L.) DC. for Zn and/or Cd accumulation and protein expression. An in vitro tissue culture system was used to control the environment and effects of the microorganisms. Treatments with higher Zn and Cd concentrations increased chlorosis and the accumulation of metals in the root and shoot. Cd treatment at low levels induced the growth of the plant, and the translocation factor was high. A dual treatment with Cd and Zn decreased the metals' toxicity and demonstrated the plant's proclivity to accumulate Cd. The SDS–PAGE and FT-IR analyses showed the effect of the metals' toxicity on protein expression and secondary structure. Moreover, using XAFS techniques, it was demonstrated that treatment with a high Zn concentration (100 mg l?1) resulted in tetrahedral coordination with mixed S/O ligation in the protein extract as compared with ZnO coordination in the protein extract from the control plant cultured in the presence of trace levels of Zn (0.04 mg l?1). This research suggested that G. pseudochina (L.) DC. had properties to tolerate a high Zn and Cd concentration, related to the sulphur proteins.

Panitlertumpai, Natthawoot; Nakbanpote, Woranan; Sangdee, Aphidech; Thumanu, Kanjana; Nakai, Izumi; Hokura, Akiko

2013-03-01

293

Cadmium effects on growth and mineral nutrition of two halophytes: Sesuvium portulacastrum and Mesembryanthemum crystallinum.  

PubMed

Growth, cadmium accumulation and potassium and calcium status were studied in two halophytes from Aizoaceae family: Sesuvium portulacastrum and Mesembryanthemum crystallinum. After multiplication, the seedlings were cultivated on nutrient solution supplemented with NaCl (100mM) and CdCl2 (0, 50, 100, 200 and 300 microM). After 1 month of treatment, plants were harvested and the dry weight, as well as the Cd, K and Ca concentrations in tissues were determined. Results showed that S. portulacastrum, a perennial halophyte with slow growth, is significantly more tolerant to Cd than M. crystallinum, an annual plant. Cd severely inhibited Mesembryanthemum growth even at the lowest Cd concentration in culture medium (50 microM), and did not modify significantly that of Sesuvium. For both halophytes, Cd accumulation was significantly higher in the roots than in the shoots. However, Cd concentration reached 350-700 microg g(-1) DM in the shoots, values characteristic of Cd hyperaccumulator plants. The addition of Cd in the culture medium led to a disturbance of Ca and especially K nutrition, suggesting the possibility to improve plant growth and Cd phytoextraction of both halophytes by increasing nutrient availability in the culture medium. PMID:16255171

Ghnaya, Tahar; Nouairi, Issam; Slama, Inès; Messedi, Dorsaf; Grignon, Claude; Abdelly, Chedly; Ghorbel, Mohamed Habib

2005-10-01

294

Plants Level of Chromium and Nickel at a Refuse Site, Any Positive Impact?  

NASA Astrophysics Data System (ADS)

Trace metals, including heavy metals can be dangerous to the biota and human beings. Consequently, a study of the accumulation of two unpopular heavy metals, Chromium (Cr) and Nickel (Ni), in four species of plants were carried out. At Ojota refuse sites (Old and New) in Lagos State, Nigeria, from where samples were taken; knowledge about these metals were scarce. The results obtained from the analysis of leaves and roots of plants showed that the sites were heavily polluted by chromium and nickel containing substances, which were indiscriminately dumped at the sites. Values were far above the background level with higher concentrations being recorded at the New Refuse Site (NRS). The concentrations obtained were also found to correlate strongly with the results of some soil physico-chemical properties, which were determined during the study. The plants used in the present research were observed to display a higher level of tolerance to metal concentration, an important characteristic of hyper-accumulator plants in phytoremediation study. Consequently, they are recommended for cultivation in non-grazing heavy metal polluted sites. However, livestock feedings and vegetable consumption at the present sites should be discouraged to avoid metal poisoning.

Ololade, I. A.; Ashoghon, A. O.; Adeyemi, O.

295

Malformed selenoproteins are removed by the ubiquitin--proteasome pathway in Stanleya pinnata.  

PubMed

Despite the widely accepted belief that selenium toxicity in plants is manifested by the misincorporation of selenocysteine into selenoproteins, there is a lack of data suggesting that selenoproteins are malformed or misfolded. Plant mechanisms to prevent the formation of selenoproteins are associated with increased selenium tolerance, yet there is no evidence to suggest that selenoproteins are malformed or potentially misfolded. We reasoned that if selenoproteins are malformed, then they might be degraded by the ubiquitin-proteasome pathway. The data demonstrate that selenate treatment induced the accumulation of both oxidized and ubiquitinated proteins, thus implicating both the 20S and 26S proteasome of Stanleya pinnata, a selenium-hyperaccumulating plant, in a selenate response. Inhibition of the proteasome increases the amount of selenium incorporated into protein, but not other elements. Furthermore, a higher percentage of selenium was found in a ubiquitinated protein fraction compared with other elements, suggesting that malformed selenoproteins are preferentially ubiquitinated and removed by the proteasome. Additionally, levels of the 20S and 26S proteasome and two heat shock proteins increase upon selenate treatment. Arabidopsis mutants with defects in the 26S proteasome have decreased selenium tolerance, which further supports the hypothesis that the 26S proteasome probably prevents selenium toxicity by removing selenoproteins. PMID:22323770

Sabbagh, Melissa; Van Hoewyk, Doug

2012-02-09

296

The role of heavy-metal ATPases, HMAs, in zinc and cadmium transport in rice.  

PubMed

The P(1B)-type heavy metal ATPases (HMAs) are diverse in terms of tissue distribution, subcellular localization, and metal specificity. Functional studies of HMAs have shown that these transporters can be divided into two subgroups based on their metal-substrate specificity: a copper (Cu)/silver (Ag) group and a zinc (Zn)/cobalt (Co)/cadmium (Cd)/lead (Pb) group. Studies on Arabidopsis thaliana and metal hyperaccumulator plants indicate that HMAs play an important role in the translocation or detoxification of Zn and Cd in plants. Rice possesses nine HMA genes, of which OsHMA1-OsHMA3 belong to the Zn/Co/Cd/Pb subgroup. OsHMA2 plays an important role in root-to-shoot translocation of Zn and Cd, and participates in Zn and Cd transport to developing seeds in rice. OsHMA3 transports Cd and plays a role in the sequestration of Cd into vacuoles in root cells. Modification of the expression of these genes might be an effective approach for reducing the Cd concentration in rice grains. PMID:23072989

Takahashi, Ryuichi; Bashir, Khurram; Ishimaru, Yasuhiro; Nishizawa, Naoko K; Nakanishi, Hiromi

2012-10-16

297

Phytoextraction of metals and rhizoremediation of PAHs in co-contaminated soil by co-planting of Sedum alfredii with ryegrass (Lolium perenne) or castor (Ricinus communis).  

PubMed

A pot experiment was conducted to investigate the potential for phytoextraction of heavy metals and rhizoremediation of polycyclic aromatic hydrocarbons (PAHs) in co-contaminated soil by co-planting a cadmium/zinc (Cd/Zn) hyperaccumulator and lead (Pb) accumulator Sedum alfredii with ryegrass (Lolium perenne) or castor (Ricinus communis). Co-planting with castor decreased the shoot biomass of S. alfredii as compared to that in monoculture. Cadmium concentration in S. alfredii shoot significantly decreased when grown with ryegrass or castor as compared to that in monoculture. However, no reduction of Zn or Pb concentration in S. alfredii shoot was detected in co-planting treatments. Total removal of either Cd, Zn, or Pb by plants was similar across S. alfredii monoculture or co-planting with ryegrass or castor, except enhanced Pb removal in S. alfredii and ryegrass co-planting treatment. Co-planting of S. alfredii with ryegrass or castor significantly enhanced the pyrene and anthracene dissipation as compared to that in the bare soil or S. alfredii monoculture. This appears to be due to the increased soil microbial population and activities in both co-planting treatments. Co-planting of S. alfredii with ryegrass or castor provides a promising strategy to mitigate both metal and PAH contaminants from co-contaminated soils. PMID:23488013

Wang, Kai; Huang, Huagang; Zhu, Zhiqiang; Li, Tingqiang; He, Zhenli; Yang, Xiaoe; Alva, Ashok

2013-01-01

298

The Nup107-160 Nucleoporin Complex Is Required for Correct Bipolar Spindle Assembly  

PubMed Central

The Nup107-160 complex is a critical subunit of the nuclear pore. This complex localizes to kinetochores in mitotic mammalian cells, where its function is unknown. To examine Nup107-160 complex recruitment to kinetochores, we stained human cells with antisera to four complex components. Each antibody stained not only kinetochores but also prometaphase spindle poles and proximal spindle fibers, mirroring the dual prometaphase localization of the spindle checkpoint proteins Mad1, Mad2, Bub3, and Cdc20. Indeed, expanded crescents of the Nup107-160 complex encircled unattached kinetochores, similar to the hyperaccumulation observed of dynamic outer kinetochore checkpoint proteins and motors at unattached kinetochores. In mitotic Xenopus egg extracts, the Nup107-160 complex localized throughout reconstituted spindles. When the Nup107-160 complex was depleted from extracts, the spindle checkpoint remained intact, but spindle assembly was rendered strikingly defective. Microtubule nucleation around sperm centrosomes seemed normal, but the microtubules quickly disassembled, leaving largely unattached sperm chromatin. Notably, Ran-GTP caused normal assembly of microtubule asters in depleted extracts, indicating that this defect was upstream of Ran or independent of it. We conclude that the Nup107-160 complex is dynamic in mitosis and that it promotes spindle assembly in a manner that is distinct from its functions at interphase nuclear pores.

Orjalo, Arturo V.; Arnaoutov, Alexei; Shen, Zhouxin; Boyarchuk, Yekaterina; Zeitlin, Samantha G.; Fontoura, Beatriz; Briggs, Steven; Dasso, Mary

2006-01-01

299

Novel Nickel Resistance Genes from the Rhizosphere Metagenome of Plants Adapted to Acid Mine Drainage? †  

PubMed Central

Metal resistance determinants have traditionally been found in cultivated bacteria. To search for genes involved in nickel resistance, we analyzed the bacterial community of the rhizosphere of Erica andevalensis, an endemic heather which grows at the banks of the Tinto River, a naturally metal-enriched and extremely acidic environment in southwestern Spain. 16S rRNA gene sequence analysis of rhizosphere DNA revealed the presence of members of five phylogenetic groups of Bacteria and the two main groups of Archaea mostly associated with sites impacted by acid mine drainage (AMD). The diversity observed and the presence of heavy metals in the rhizosphere led us to construct and screen five different metagenomic libraries hosted in Escherichia coli for searching novel nickel resistance determinants. A total of 13 positive clones were detected and analyzed. Insights about their possible mechanisms of resistance were obtained from cellular nickel content and sequence similarities. Two clones encoded putative ABC transporter components, and a novel mechanism of metal efflux is suggested. In addition, a nickel hyperaccumulation mechanism is proposed for a clone encoding a serine O-acetyltransferase. Five clones encoded proteins similar to well-characterized proteins but not previously reported to be related to nickel resistance, and the remaining six clones encoded hypothetical or conserved hypothetical proteins of uncertain functions. This is the first report documenting nickel resistance genes recovered from the metagenome of an AMD environment.

Mirete, Salvador; de Figueras, Carolina G.; Gonzalez-Pastor, Jose E.

2007-01-01

300

Vegetation composition and heavy metal uptake by wild plants at three contaminated sites in Xiangxi area, China.  

PubMed

The plant species composition and their ability to accumulate heavy metals were investigated at three contaminated sites in Xiangxi area, Southern China. The concentrations of Cd, Pb, Zn, and Cu in more than 363 samples of 125 plant species were analyzed in the present study. The average concentrations of Cd, Pb, Zn, and Cu in the plants were 19, 81, 637, and 8 mg kg(-1), respectively. The highest concentration of Cd in above-ground plant tissues was found to be 287 mg kg(-1) in the leaves of Lobelia chinensis Lour, at the Datianwan site, followed by Solamim nigrum L. with 99 mg kg(-1) Cd in the leaves. They might be potential Cd hyperaccumulators. At the three contaminated sites, some dominant and relative dominant species with high accumulation potential of metals, such as Kalimeris indice (L.) Sch.-Bip. and Solanum nigrum L., might be suitable for use in the phytoextraction of contaminated soils. The dominant and relative dominant species with low accumulation of metals and dense fibrous root systems, such as Imperata cylindrical (L.) Beauv. var. major C. E. and Miscanthus floridulus (Labill.) Warb., might be suitable for stabilizing such metal contaminated sites. PMID:16401571

Peng, Kejian; Li, Xiangdong; Luo, Chunling; Shen, Zhenguo

2006-01-01

301

Stable Transformation of Ferns Using Spores as Targets: Pteris vittata and Ceratopteris thalictroides1[W][OPEN  

PubMed Central

Ferns (Pteridophyta) are very important members of the plant kingdom that lag behind other taxa with regards to our understanding of their genetics, genomics, and molecular biology. We report here, to our knowledge, the first instance of stable transformation of fern with recovery of transgenic sporophytes. Spores of the arsenic hyperaccumulating fern Pteris vittata and tetraploid ‘C-fern Express’ (Ceratopteris thalictroides) were stably transformed by Agrobacterium tumefaciens with constructs containing the P. vittata actin promoter driving a GUSPlus reporter gene. Reporter gene expression assays were performed on multiple tissues and growth stages of gametophytes and sporophytes. Southern-blot analysis confirmed stable transgene integration in recovered sporophytes and also confirmed that no plasmid from A. tumefaciens was present in the sporophyte tissues. We recovered seven independent transformants of P. vittata and four independent C. thalictroides transgenics. Inheritance analyses using ?-glucuronidase (GUS) histochemical staining revealed that the GUS transgene was stably expressed in second generation C. thalictroides sporophytic tissues. In an independent experiment, the gusA gene that was driven by the 2× Cauliflower mosaic virus 35S promoter was bombarded into P. vittata spores using biolistics, in which putatively stable transgenic gametophytes were recovered. Transformation procedures required no tissue culture or selectable marker genes. However, we did attempt to use hygromycin selection, which was ineffective for recovering transgenic ferns. This simple stable transformation method should help facilitate functional genomics studies in ferns.

Muthukumar, Balasubramaniam; Joyce, Blake L.; Elless, Mark P.; Stewart, C. Neal

2013-01-01

302

Hepatocyte growth factor leads to recovery from alcohol-induced fatty liver in rats  

PubMed Central

A fatty liver is characterized by the hyperaccumulation of lipids within hepatocytes and is often caused by excessive alcohol intake. Rats fed ethanol-containing diets for 37 days showed remarkable increase in hepatic lipids and lipid droplet accumulation in the hepatocytes, indicating the onset of alcoholic fatty liver. Administration of hepatocyte growth factor (HGF) for the last seven days of ethanol treatment markedly decreased hepatic lipids to a level lower than that seen before HGF treatment. In contrast, serum levels of lipids and lipoproteins increased with HGF administration. Primary cultured hepatocytes prepared from the fatty liver retained lipid droplets during a 48-hour culture. However, when cultured in the presence of HGF, intracellular lipid concentrations decreased and lipid secretion was enhanced. Consistent with these events, HGF stimulated the rate of protein synthesis of apolipoprotein B (apoB) and enhanced subsequent mobilization of lipids into the medium. These results indicate that HGF administration induced recovery from the fatty liver, at least in part, by enhancing apoB synthesis and the subsequent mobilization of lipids from hepatocytes with fatty change. The possibility that HGF can be therapeutic for subjects with an alcohol-related fatty liver warrants further attention.

Tahara, Minoru; Matsumoto, Kunio; Nukiwa, Toshihiro; Nakamura, Toshikazu

1999-01-01

303

Potential of weed species applied to remediation of soils contaminated with heavy metals.  

PubMed

To screen out a series of ideal plants that can effectively remedy contaminated soils by heavy metals is the main groundwork of phytoremediation engineering and the first step of its commercial application on a large scale. In this study, accumulation and endurance of 45 weed species in 16 families from an agricultural site were in situ examined by using the pot-culture field experiment, and the remediation potential of some weed species with high accumulation of heavy metals was assayed. The results showed that Solanum nigrum and Conyza canadensis can not only accumulate high concentration of Cd, but also strongly endure to single Cd and Cd-Pb-Cu-Zn combined pollution. Thus 2 weed species can be regarded as good hyperaccumulators for the remediation of Cd-contaminated soils. Although there were high Cd-accumulation in Artemigia selengensis, Znula britannica and Cephalanoplos setosum, their biomass was adversely affected due to action of heavy metals in the soils. If the problem of low endurance to heavy metals can be solved by a reinforcer, 3 weed species can be perhaps applied commercially. PMID:15559831

Wei, Shu-He; Zhou, Qi-Xing; Wang, Xin; Cao, Wei; Ren, Li-Ping; Song, Yu-Fang

2004-01-01

304

RanGAP2 Mediates Nucleocytoplasmic Partitioning of the NB-LRR Immune Receptor Rx in the Solanaceae, Thereby Dictating Rx Function[W][OA  

PubMed Central

The potato (Solanum tuberosum) nucleotide binding–leucine-rich repeat immune receptor Rx confers resistance to Potato virus X (PVX) and requires Ran GTPase-activating protein 2 (RanGAP2) for effective immune signaling. Although Rx does not contain a discernible nuclear localization signal, the protein localizes to both the cytoplasm and nucleus in Nicotiana benthamiana. Transient coexpression of Rx and cytoplasmically localized RanGAP2 sequesters Rx in the cytoplasm. This relocation of the immune receptor appeared to be mediated by the physical interaction between Rx and RanGAP2 and was independent of the concomitant increased GAP activity. Coexpression with RanGAP2 also potentiates Rx-mediated immune signaling, leading to a hypersensitive response (HR) and enhanced resistance to PVX. Besides sequestration, RanGAP2 also stabilizes Rx, a process that likely contributes to enhanced defense signaling. Strikingly, coexpression of Rx with the Rx-interacting WPP domain of RanGAP2 fused to a nuclear localization signal leads to hyperaccumulation of both the WPP domain and Rx in the nucleus. As a consequence, both Rx-mediated resistance to PVX and the HR induced by auto-active Rx mutants are significantly suppressed. These data show that a balanced nucleocytoplasmic partitioning of Rx is required for proper regulation of defense signaling. Furthermore, our data indicate that RanGAP2 regulates this partitioning by serving as a cytoplasmic retention factor for Rx.

Tameling, Wladimir I.L.; Nooijen, Claudia; Ludwig, Nora; Boter, Marta; Slootweg, Erik; Goverse, Aska; Shirasu, Ken; Joosten, Matthieu H.A.J.

2010-01-01

305

The effect of excess Zn on mineral nutrition and antioxidative response in rapeseed seedlings.  

PubMed

Zinc (Zn) is a necessary element for plants, but excess Zn can be detrimental. To investigate Zn toxicity, rapeseed (Brassica napus) seedlings were treated with 0.07-1.12 mM Zn for 7d. Inhibition of plant growth along with root damage, chlorosis and decreased chlorophyll (a and b) content in newly expanded leaves (the second and third leaves formed following cotyledons) were found under Zn stress. The Zn content increased in plants under external Zn stress, while concentrations of phosphorus, copper, iron, manganese and magnesium reduced significantly, especially in roots. Meanwhile, increased lipid peroxidation was detected biochemically and histochemically. Compared with controls, NADH oxidase and peroxidase (POD) activity increased in leaves and roots of plants under high Zn, but superoxide dismutase (SOD), catalase and ascorbate peroxidase activities decreased. The changes in glutathione S-transferase activity and in ascorbic acid, dehydroascorbate, non-protein thiols and glutathione contents were also measured under Zn stress. Isoforms of SOD and POD were separated using non-denaturing polyacrylamide gel electrophoresis and their activities were analyzed. Our results suggested that excess Zn exerts its toxicity partially through disturbing nutrient balance and inducing oxidative stress in plants. These data will be helpful for better understanding of toxicity of Zn and the adaptive mechanism in Zn non-hyperaccumulator plants. PMID:19328518

Wang, Chao; Zhang, Song He; Wang, Pei Fang; Hou, Jun; Zhang, Wen Jing; Li, Wei; Lin, Zhi Ping

2009-03-27

306

Response of the lichen Cladonia rei Schaer. to strong heavy metal contamination of the substrate.  

PubMed

The phenomenon of mass occurrence of the lichen Cladonia rei in extremely contaminated post-smelting slag dumps was studied in relation to metal accumulation capacity of this lichen. The research was aimed to evaluate the relationships between element contents in the thalli and in the corresponding substrate. The study was conducted in terms of a wide spectrum of Zn, Cd, Pb and As contents. The concentrations of these elements in the lichen thalli and substrate samples were measured. Various regression models were considered to find the best fitted one that greatly reflects the dependencies. Various Cladonia species and the hyperaccumulator Diploschistes muscorum were also included in the study for comparison purposes. Specific non-linear regression models described by a power function reflected relationships between Zn and Cd contents in C. rei thalli and in the host substrate in the most reliable way. The relationship for As was also noted, but none significant model was found. Contrarily, Pb concentrations in the thalli varied independently of the metal levels in the substrate. Nevertheless, the concentrations of all measured heavy metals in C. rei thalli are relatively low considering the frequently enormous substrate contamination. Different Cladonia species demonstrated a generally similar accumulation capacity and could be considered as weak accumulators. The restrained accumulation pattern may be one of the important attributes of C. rei which facilitates its colonisation of extremely contaminated dumps. This finding highlights ecological importance of this species as stable and resistant pioneer in such affected sites. PMID:23589242

Osyczka, Piotr; Rola, Kaja

2013-04-16

307

Cryptococcus neoformans copper detoxification machinery is critical for fungal virulence.  

PubMed

Copper (Cu) is an essential metal that is toxic at high concentrations. Thus, pathogens often rely on host Cu for growth, but host cells can hyperaccumulate Cu to exert antimicrobial effects. The human fungal pathogen Cryptococcus neoformans encodes many Cu-responsive genes, but their role in infection is unclear. We determined that pulmonary C. neoformans infection results in Cu-specific induction of genes encoding the Cu-detoxifying metallothionein (Cmt) proteins. Mutant strains lacking CMTs or expressing Cmt variants defective in Cu-coordination exhibit severely attenuated virulence and reduced pulmonary colonization. Consistent with the upregulation of Cmt proteins, C. neoformans pulmonary infection results in increased serum Cu concentrations and increases and decreases alveolar macrophage expression of the Cu importer (Ctr1) and ATP7A, a transporter implicated in phagosomal Cu compartmentalization, respectively. These studies indicate that the host mobilizes Cu as an innate antifungal defense but C. neoformans senses and neutralizes toxic Cu to promote infection. PMID:23498952

Ding, Chen; Festa, Richard A; Chen, Ying-Lien; Espart, Anna; Palacios, Òscar; Espín, Jordi; Capdevila, Mercè; Atrian, Sílvia; Heitman, Joseph; Thiele, Dennis J

2013-03-13

308

Arabidopsis and the Genetic Potential for the Phytoremediation of Toxic Elemental and Organic Pollutants  

PubMed Central

In a process called phytoremediation, plants can be used to extract, detoxify, and/or sequester toxic pollutants from soil, water, and air. Phytoremediation may become an essential tool in cleaning the environment and reducing human and animal exposure to potential carcinogens and other toxins. Arabidopsis has provided useful information about the genetic, physiological, and biochemical mechanisms behind phytoremediation, and it is an excellent model genetic organism to test foreign gene expression. This review focuses on Arabidopsis studies concerning: 1) the remediation of elemental pollutants; 2) the remediation of organic pollutants; and 3) the phytoremediation genome. Elemental pollutants include heavy metals and metalloids (e.g., mercury, lead, cadmium, arsenic) that are immutable. The general goal of phytoremediation is to extract, detoxify, and hyperaccumulate elemental pollutants in above-ground plant tissues for later harvest. A few dozen Arabidopsis genes and proteins that play direct roles in the remediation of elemental pollutants are discussed. Organic pollutants include toxic chemicals such as benzene, benzo(a)pyrene, polychlorinated biphenyls, trichloroethylene, trinitrotoluene, and dichlorodiphenyltrichloroethane. Phytoremediation of organic pollutants is focused on their complete mineralization to harmless products, however, less is known about the potential of plants to act on complex organic chemicals. A preliminary survey of the Arabidopsis genome suggests that as many as 700 genes encode proteins that have the capacity to act directly on environmental pollutants or could be modified to do so. The potential of the phytoremediation proteome to be used to reduce human exposure to toxic pollutants appears to be enormous and untapped.

Cobbett, Christopher S.; Meagher, Richard B.

2002-01-01

309

Tie-dyed2 encodes a callose synthase that functions in vein development and affects symplastic trafficking within the phloem of maize leaves.  

PubMed

The tie-dyed2 (tdy2) mutant of maize (Zea mays) displays variegated green and yellow leaves. Intriguingly, the yellow leaf tissues hyperaccumulate starch and sucrose, the soluble sugar transported long distance through the phloem of veins. To determine the molecular basis for Tdy2 function, we cloned the gene and found that Tdy2 encodes a callose synthase. RNA in situ hybridizations revealed that in developing leaves, Tdy2 was most highly expressed in the vascular tissue. Comparative expression analysis with the vascular marker maize PINFORMED1a-yellow fluorescent protein confirmed that Tdy2 was expressed in developing vein tissues. To ascertain whether the defect in tdy2 leaves affected the movement of sucrose into the phloem or its long-distance transport, we performed radiolabeled and fluorescent dye tracer assays. The results showed that tdy2 yellow leaf regions were defective in phloem export but competent in long-distance transport. Furthermore, transmission electron microscopy of tdy2 yellow leaf regions showed incomplete vascular differentiation and implicated a defect in cell-to-cell solute movement between phloem companion cells and sieve elements. The disruption of sucrose movement in the phloem in tdy2 mutants provides evidence that the Tdy2 callose synthase functions in vascular maturation and that the vascular defects result in impaired symplastic trafficking into the phloem translocation stream. PMID:22932757

Slewinski, Thomas L; Baker, R Frank; Stubert, Adam; Braun, David M

2012-08-29

310

Assessment of bioaccumulation of heavy metals by different plant species grown on fly ash dump.  

PubMed

A field experiment was conducted on a 10-hectare area on fly ash dump at Khaperkheda Thermal Power Plant, Nagpur, India, where different ecologically and economically important plant species were planted using bioremediation technology. The technology involves the use of organic amendment and selection of suitable plant species along with site-specific nitrogen-fixing strains of biofertilizers. The study was conducted to find out the metal accumulation potential of different plant species. The total heavy metal contents in fly ash were determined and their relative abundance was found in the order of Fe>Mn>Zn>Cu>Ni>Cr>Pb>Cd. Fly ash samples had acidic pH, low electrical conductivity, low level of organic carbon and trace amounts of N and P. Plantation of divergent species was done on fly ash dump using the bioremediation technique. After 3 years of plantation, luxuriant growth of these species was found covering almost the entire fly ash dump. The results of the metal analysis of these species indicated that iron accumulated to the greatest extent in vegetation followed by Mn, Ni, Zn, Cu, Cr and Pb. Cassia siamea was found to accumulate all metals at higher concentrations compared to other species. The experimental study revealed that C. siamea could be used as a hyper-accumulator plant for bioremediation of fly ash dump. PMID:19171381

Jambhulkar, Hemlata P; Juwarkar, Asha A

2009-01-25

311

tie-dyed1 Regulates carbohydrate accumulation in maize leaves.  

PubMed

Acquisition of cell identity requires communication among neighboring cells. To dissect the genetic pathways regulating cell signaling in later leaf development, a screen was performed to identify mutants with chloroplast pigmentation sectors that violate cell lineage boundaries in maize (Zea mays) leaves. We have characterized a recessive mutant, tie-dyed1 (tdy1), which develops stable, nonclonal variegated yellow and green leaf sectors. Sector formation requires high light, occurs during a limited developmental time, and is restricted to leaf blade tissue. Yellow tdy1 sectors accumulate excessive soluble sugars and starch, whereas green sectors appear unaffected. Significantly, starch accumulation precedes chlorosis in cells that will become a yellow sector. Retention of carbohydrates in tdy1 leaves is associated with a delay in reproductive maturity, decreased stature, and reduced yield. To explain the tdy1 sectoring pattern, we propose a threshold model that incorporates the light requirement and the hyperaccumulation of photoassimilates. A possible function consistent with this model is that TDY1 acts as a sugar sensor to regulate an inducible sugar export pathway as leaves develop under high light conditions. PMID:17071639

Braun, David M; Ma, Yi; Inada, Noriko; Muszynski, Michael G; Baker, R Frank

2006-10-27

312

Accumulation of arsenic, lead, copper, and zinc, and synthesis of phytochelatins by indigenous plants of a mining impacted area.  

PubMed

Several native plants, able to grow in an unconfined mining impacted area that is now in close vicinity with urban areas, were evaluated for their ability to accumulate heavy metals. The main soil contaminants were As, Pb, Cu, and Zn. Sampling of the rhizospheric metal polluted soil showed that Euphorbia prostrata Aiton, Parthenium incanum Kunth, and Zinnia acerosa (DC.) A. Gray were able to grow in the presence of high amounts of mixtures of these elements. The plants accumulated the metals in the above ground parts and increased the synthesis of thiol molecules. E. prostrata showed the highest capacity for accumulation of the mixture of elements (588 ?g g DW(-1)). Analysis of the thiol-molecules profile showed that these plants synthesized high amounts of long-chain phytochelatins, accompanied by low amounts of monothiol molecules, which may be related to their higher resistance to As and heavy metals. The three plants showed translocation factors from roots to leaves >1 for As, Pb, Cu, and Zn. Thus, by periodically removing aerial parts, these plants could be useful for the phytoremediation of semi-arid and arid mining impacted areas, in which metal hyper-accumulator plants are not able to grow. PMID:23649544

Machado-Estrada, Blenda; Calderón, Jaqueline; Moreno-Sánchez, Rafael; Rodríguez-Zavala, José S

2012-11-28

313

Intraspecific differences of arbuscular mycorrhizal fungi in their impacts on arsenic accumulation by Pteris vittata L.  

PubMed

It has been shown that Pteris vittata, an arsenic hyperaccumulator, could be colonized by arbuscular mycorrhizal (AM) fungi either in controlled conditions or at field sites. However, physiological mechanisms of AM fungi influencing As accumulation and tolerance in the plant are not fully elucidated. Two predominant fungal species, Glomus mosseae and Glomus geosporum, and a rapidly sporulating fungal species, Glomus etunicatum, associated with P. vittata were isolated from As-contaminated soils. Two uncontaminated isolates, G. mosseae and G. etunicatum, served as reference isolates. Based on germination of spores exposed to elevated As, Pb and Zn concentrations, two contrasting isolates of G. mosseae were selected to investigate As accumulation in two populations of P. vittata [from an uncontaminated site of Hong Kong (HK) and an As-contaminated site located in Jinchuantang (JCT) of Hunan Province, China, respectively] under hydroponic culture and pot trials. At lower levels of As exposure (50-200 microM), both uncontaminated and metal-contaminated isolates of G. mosseae significantly increased short-term As influx into roots of P. vittata. However, at higher levels of As exposure (400-1000 microM), only uncontaminated isolates significantly increased short-term As influx into roots. When growing on 100mg As kg(-1) soils, uncontaminated isolates exhibited a higher level of colonization in roots of P. vittata than metal-contaminated isolates and only the former significantly increased As accumulation in roots of HK population and in fronds of JCT population. It was concluded that there were intraspecific differences of AM fungi in their impacts on As accumulation by P. vittata. PMID:19535126

Wu, F Y; Ye, Z H; Wong, M H

2009-06-16

314

Selenite precipitation by a rhizospheric strain of Stenotrophomonas sp. isolated from the root system of Astragalus bisulcatus: a biotechnological perspective.  

PubMed

A bacterial strain (SeITE02), related to the species Stenotrophomonas maltophilia and resistant to selenite (SeIV) up to 50 mM in the growth medium, was isolated from rhizospheric soil of a selenium hyperaccumulator plant, the legume Astragalus bisulcatus. The influence of SeIV on the active growth of this Se-tolerant bacterial strain has been investigated in oxic conditions, along with the isolate's ability to reduce selenite to elemental selenium (Se(0)). Interestingly, concentrations of 0.5 mM SeIV were wholly reduced by strain SeITE02 in liquid culture within 52 h. Moreover, 87% of SeIV added to the growth medium at the initial concentration of 2.0 mM underwent again reduction in 120 h. Actually, a selenite-mediated induction of a sort of adaptive response to detrimental SeIV effects magnified the efficiency of SeITE02 in reducing this toxic oxyanion. Furthermore, the SeIV influence on cell morphology of strain SeITE02 was evidenced by phase-contrast and electron microscopy analyses. In particular, transmission electron microscopy (TEM)-energy-dispersive X-ray (EDX) analysis of S. maltophilia strain SeITE02, grown in presence of SeIV, showed electron-dense Se(0) granules either in the cell cytoplasm or in the extracellular space. Therefore, the capability of strain SeITE02 to quickly reduce soluble and harmful SeIV to insoluble and unavailable Se(0) may be looked at as a promising exploitable option for the setup of low-cost biological treatments tailored to manage contamination in selenium-laden effluents. PMID:15661289

Di Gregorio, Simona; Lampis, Silvia; Vallini, Giovanni

2005-02-01

315

Dual roles of reactive oxygen species and NADPH oxidase RBOHD in an Arabidopsis-Alternaria pathosystem.  

PubMed

Arabidopsis (Arabidopsis thaliana) NADPH oxidases have been reported to suppress the spread of pathogen- and salicylic acid-induced cell death. Here, we present dual roles of RBOHD (for respiratory burst oxidase homolog D) in an Arabidopsis-Alternaria pathosystem, suggesting either initiation or prevention of cell death dependent on the distance from pathogen attack. Our data demonstrate that a rbohD knockout mutant exhibits increased spread of cell death at the macroscopic level upon inoculation with the fungus Alternaria brassicicola. However, the cellular patterns of reactive oxygen species accumulation and cell death are fundamentally different in the AtrbohD mutant compared with the wild type. Functional RBOHD causes marked extracellular hydrogen peroxide accumulation as well as cell death in distinct, single cells of A. brassicicola-infected wild-type plants. This single cell response is missing in the AtrbohD mutant, where infection triggers spreading-type necrosis preceded by less distinct chloroplastic hydrogen peroxide accumulation in large clusters of cells. While the salicylic acid analog benzothiadiazole induces the action of RBOHD and the development of cell death in infected tissues, the ethylene inhibitor aminoethoxyvinylglycine inhibits cell death, indicating that both salicylic acid and ethylene positively regulate RBOHD and cell death. Moreover, A. brassicicola-infected AtrbohD plants hyperaccumulate ethylene and free salicylic acid compared with the wild type, suggesting negative feedback regulation of salicylic acid and ethylene by RBOHD. We propose that functional RBOHD triggers death in cells that are damaged by fungal infection but simultaneously inhibits death in neighboring cells through the suppression of free salicylic acid and ethylene levels. PMID:19726575

Pogány, Miklós; von Rad, Uta; Grün, Sebastian; Dongó, Anita; Pintye, Alexandra; Simoneau, Philippe; Bahnweg, Günther; Kiss, Levente; Barna, Balázs; Durner, Jörg

2009-09-02

316

Organometallic geochemistry. Isolation and identification of organoarsenic and inorganic arsenic compounds from Green River formation oil shale  

SciTech Connect

Transformations and bioaccumulation of trace metals and metalloids, especially arsenic, are well known to occur in modern microorganisms, including the bacteria molds, and marine plankton or algae. Such microflora demonstrate capacities for uptake of both inorganic forms of elements, and in some instances, are shown to involve biomethylation of inorganic substrates which result in cellular incorporation of organometal(loid)s, e.g., methylarsonic acid or dimethylarsonic acid. Arsenic is known to bioaccumulate in higher marine organisms to a substantial degree where it resides in some shellfish tissues as arsenobetaine. Similar considerations for ancient metal(loid) uptake or transformations appear quite reasonable for primordial microflora, especially the algae which account for the present ubiquitous distribution of kerogen in shale rocks. In general, the fossil deposition record suggests that substantial metal(loid) accumulation also occurred in higher plants which underwent diagenesis to form modern petroleum and coal deposits. In many instances, various present-day species of plants are known to both selectively and extensively hyperaccumulate various metal(loid)s to such a degree that geochemical prospecting is feasible by correlating metal concentration profiles with local flora. It is not unexpected, therefore, to discern characteristic concentration patterns for trace elements in various fossil deposits - whether we regard these as essential or toxic to life and to expect gross differences in the profiles between the three main types: coal, kerogen, and petroleum. Similarly expected, though far more subtle, we might anticipate that element distributions for these three main fossil sources also depend upon specific sites, and reflect their terrestrial or marine origins, subsequent geochemical history, and maturation.

Fish, R.H.; Brinckman, F.E.

1983-02-01

317

Characterization of endophytic Rahnella sp. JN6 from Polygonum pubescens and its potential in promoting growth and Cd, Pb, Zn uptake by Brassica napus.  

PubMed

Microbe-assisted phytoremediation has been considered as a promising measure for the remediation of heavy metal-polluted soils. In this study, a metal-tolerance and plant growth-promoting endophytic bacterium JN6 was firstly isolated from roots of Mn-hyperaccumulator Polygonum pubescens grown in metal-contaminated soil and identified as Rahnella sp. based on 16S rDNA gene sequence analysis. Strain JN6 showed very high Cd, Pb and Zn tolerance and effectively solubilized CdCO(3), PbCO(3) and Zn(3)(PO(4))(2) in culture solution. The isolate produced plant growth-promoting substances such as indole-3-acetic acid, siderophore, 1-aminocyclopropane-1-carboxylic deaminase, and also solubilized inorganic phosphate. Based upon its ability in metal tolerance and solubilization, the isolate JN6 was further studied for its effects on the growth and accumulation of Cd, Pb and Zn in Brassica napus (rape) by pot experiments. Rape plants inoculated with the isolate JN6 had significantly higher dry weights, concentrations and uptake of Cd, Pb and Zn in both above-ground and root tissues than those without inoculation grown in soils amended with Cd (25 mg kg(-1)), Pb (200 mg kg(-1)) or Zn (200 mg kg(-1)). The isolate also showed a high level of colonization in tissue interior of rapes. The present results demonstrated that Rahnella sp. JN6 is a valuable microorganism, which can cost-effectively improve the efficiency of phytoremediation in soils contaminated by Cd, Pb and Zn. PMID:23177711

He, Huaidong; Ye, Zhihong; Yang, Danjing; Yan, Junlan; Xiao, Li; Zhong, Ting; Yuan, Ming; Cai, Xinde; Fang, Zhanqiang; Jing, Yuanxiao

2012-11-21

318

Shoot-to-Root Signal Transmission Regulates Root Fe(III) Reductase Activity in the dgl Mutant of Pea.  

PubMed Central

To understand the root, shoot, and Fe-nutritional factors that regulate root Fe-acquisition processes in dicotyledonous plants, Fe(III) reduction and net proton efflux were quantified in root systems of an Fe-hyperaccumulating mutant (dgl) and a parental (cv Dippes Gelbe Viktoria [DGV]) genotype of pea (Pisum sativum). Plants were grown with (+Fe treated) or without (-Fe treated) added Fe(III)-N,N'-ethylenebis[2-(2-hydroxyphenyl)-glycine] (2 [mu]M); root Fe(III) reduction was measured in solutions containing growth nutrients, 0.1 mM Fe(III)-ethylenediaminetetraacetic acid, and 0.1 mM Na2-bathophenanthrolinedisulfonic acid. Daily measurements of Fe(III) reduction (d 10-20) revealed initially low rates in +Fe-treated and -Fe-treated dgl, followed by a nearly 5-fold stimulation in rates by d 15 for both growth types. In DGV, root Fe(III) reductase activity increased only minimally by d 20 in +Fe-treated plants and about 3-fold in -Fe-treated plants, beginning on d 15. Net proton efflux was enhanced in roots of -Fe-treated DGV and both dgl growth types, relative to +Fe-treated DGV. In dgl, the enhanced proton efflux occurred prior to the increase in root Fe(III) reductase activity. Reductase studies using plants with reciprocal shoot:root grafts demonstrated that shoot expression of the dgl gene leads to the generation of a transmissible signal that enhances Fe(III) reductase activity in roots. The dgl gene product may alter or interfere with a normal component of a signal transduction mechanism regulating Fe homeostasis in plants.

Grusak, M. A.; Pezeshgi, S.

1996-01-01

319

Vps1 in the late endosome-to-vacuole traffic.  

PubMed

Vacuolar protein sorting 1 (Vps1), the yeast homolog to human dynamin, is a GTP hydrolyzing protein, which plays an important role in protein sorting and targeting between the Golgi and late endosomal compartments. In this study, we assessed the functional significance of Vps1 in the membrane traffic towards the vacuole. We show here that vps1 delta cells accumulated FM4-64 to a greater extent than wild-type (WT))cells, suggesting slower endocytic degradation traffic toward the vacuole. In addition, we observed that two endosome-to-vacuole traffic markers, DsRed-FYVE and Ste2-GFP, were highly accumulated in Vps1-deficient cells, further supporting Vps1's implication in efficient trafficking of endocytosed materials to the vacuole. Noteworthy, a simultaneous imaging analysis in conjunction with FM4-64 pulse-chase experiment further revealed that Vps1 plays a role in late endosome to the vacuole transport. Consistently, our subcellular localization analysis showed that Vps1 is present at the late endosome. The hyperaccumulation of endosomal intermediates in the vps1 mutant cells appears to be caused by the disruption of integrity of HOPS tethering complexes, manifested by mislocalization of Vps39 to the cytoplasm. Finally, we postulate that Vps1 functions together with the Endosomal Sorting Complex Required for Transport (ESCRT) complex at the late endosomal compartments, based on the observation that the double mutants, in which VPS1 along with singular ESCRT I, II and III genes have been disrupted, exhibited synthetic lethality. Together, we propose that Vps1 is required for correct and efficient trafficking from the late endosomal compartments to the vacuole. PMID:23385815

Hayden, Jacob; Williams, Michelle; Granich, Ann; Ahn, Hyoeun; Tenay, Brandon; Lukehart, Joshua; Highfill, Chad; Dobard, Sarah; Kim, Kyoungtae

2013-03-01

320

Soil aluminium uptake and accumulation by Paspalum notatum.  

PubMed

Paspalum notatum Flugge has been widely utilized for the purpose of ecological restoration of degraded land in the tropics and subtropics, where soil active aluminium (Al) is usually high as a result of acidification. Pot experiments were conducted to determine Al toxicity on P. notatum and to compare its potential to remove Al with another three plant species, Vetiveria zizanioides, Tristania conferta and Schima wallichii. In the Al addition experiment, the biomass of P. notatum and Al accumulation significantly decreased as the added Al concentration increased, but Al concentration in the plant markedly increased. A parallel experiment was conducted with the above four species, grown in lateritic soil and in oil shale waste containing high concentration of active Al. The biomasses of all four species were reduced obviously in the waste compared to in the soil. The effects of substrate on Al concentration, accumulation and translocation efficiency differed among species, and plants had significantly higher Al accumulation factors when grown in the soil than in the waste. Most of the Al taken up by P. notatum was transferred to above-ground parts; as a result, Al concentration in stems and leaves became quite high, over 1000 or even 3000 mg kg(-1); whereas for the other three species, Al concentration in shoots was much lower than in roots. Paspalum notatum was therefore much higher than the other three species with regard to Al translocation efficiency and therefore P. notatum may be regarded as both an effective Al hyper-accumulator and a potential Al hyper-remover. PMID:19423590

Huang, Juan; Xia, Hanping; Li, Zhi'an; Xiong, Yanmei; Kong, Guohui; Huang, Juan

2009-05-07

321

Phytoaccumulation of trace elements by wetland plants: 3. Uptake and accumulation of ten trace elements by twelve plant species  

SciTech Connect

Interest is increasing in using wetland plants in constructed wetlands to remove toxic elements from polluted wastewater. To identify those wetland plants that hyperaccumulate trace elements, 12 plant species were tested for their efficiency to bioconcentrate 10 potentially toxic trace elements including As, b, Cd, Cr, Cu, Pb, Mn, Hg, Ni, and Se. Individual plants were grown under carefully controlled conditions and supplied with 1 mg L{sup {minus}1} of each trace element individually for 10 d. Except B, all elements accumulated to much higher concentrations in roots than in shoots. Highest shoot tissue concentrations (mg kg{sup {minus}1} DW) of the various trace elements were attained by the following species: umbrella plant (Cyperus alternifolius L.) for Mn (198) and Cr (44); water zinnia (Wedelia trilobata Hitchc.) for Cd (148) and Ni (80); smartweed (Polygonum hydropiperoides Michx.) for Cu (95) and Pb (64); water lettuce (Pistia stratiotes L.) for Hg (92), As (34), and Se (39); and mare's tail (hippuris vulgaris L.) for B (1132). Whereas, the following species attained the highest root tissue concentrations (mg kg{sup {minus}1} DW); stripped rush (Baumia rubiginosa) for Mn (1683); parrot's feather (Myriophyllum brasiliense Camb.) for Cd (1426) and Ni (1077); water lettuce for Cu (1038), Hg (1217), and As (177); smartweed for Cr (2980) and Pb (1882); mare's tail for B (1277); and monkey flower (Mimulus guttatus Fisch.) for Se (384). From a phytoremediation perspective, smartweed was probably the best plant species for trace element removal from wastewater due to its faster growth and higher plant density.

Qian, J.H.; Zayed, A.; Zhu, Y.L.; Yu, M.; Terry, N.

1999-10-01

322

Phytoremediation: using green plants to clean up contaminate soil, groundwater, and wastewater  

SciTech Connect

Phytoremediation, an emerging cleanup technology for contaminated soils, groundwater, and wastewater that is both low-tech and low-cost, is defined as the engineered use of green plants (including grasses, forbs, and woody species) to remove, contain, or render harmless such environmental contaminants as heavy metals, trace elements, organic compounds and radioactive compounds in soil or water. Our research includes a successful field demonstration of a plant bioreactor for processing the salty wastewater from petroleum wells; the demonstration is currently under way at a natural gas well site in Oklahoma, in cooperation with Devon Energy Corporation. A greenhouse experiment on zinc uptake in hybrid poplar (Populus sp.) was initiated in 1995. These experiments are being conducted to confirm and extend field data indicating high levels of zinc (4,200 ppm) in leaves of hybrid poplar growing as a cleanup system at a site with zinc contamination in the root zone of some of the trees. Analyses of soil water from experimental pots that had received several doses of zinc indicated that the zinc was totally sequestered by the plants in about 4 hours during a single pass through the root system. The data also showed concentrations of sequestered metal of >38,000 ppm Zn in the dry root tissue. These levels of sequestered zinc exceed the levels found in either roots or tops of many of the known ``hyperaccumulator`` species. Because the roots sequester most of the contaminant taken up in most plants, a major objective of this program is to determine the feasibility of root harvesting as a method to maximize the removal of contaminants from soils. Available techniques and equipment for harvesting plant roots, including young tree roots, are being evaluated and modified as necessary for use with phytoremediation plants.

Negri, M.C.; Hinchman, R.R. [Argonne National Lab., IL (United States); Gatliff, E.G. [Applied Natural Sciences, Inc., Hamilton, OH (United States)

1996-07-01

323

Simultaneous determination of inorganic and organic antimony species by using anion exchange phases for HPLC-ICP-MS and their application to plant extracts of Pteris vittata.  

PubMed

Antimony is a common contaminant at abandoned sites for non-ferrous ore mining and processing. Because of the possible risk of antimony by transfer to plants growing on contaminated sites, it is of importance to analyze antimony and its species in such biota. A method based on high performance liquid chromatographic separation and inductively coupled plasma mass spectrometric detection (HPLC-ICP-MS) was developed to determine inorganic antimony species such as Sb(III) and Sb(V) as well as possible antimony-organic metabolisation products of the antimony transferred into plant material within one chromatographic run. The separation is performed using anion chromatography on a strong anion exchange column (IonPac AS15/AG 15). Based on isocratic optimizations for the separation of Sb(III) and Sb(V) as well as Sb(V) and trimenthylated Sb(V) (TMSb(V)), a chromatographic method with an eluent gradient was developed. The suggested analytical method was applied to aqueous extracts of Chinese break fern Pteris vittata samples. The transfer of antimony from spiked soil composites into the fern, which is known as a hyperaccumulator for arsenic, was investigated under greenhouse conditions. Remarkable amounts of antimony were transferred into roots and leaves of P. vittata growing on spiked soil composites. Generally, P. vittata accumulates not only arsenic (as shown in a multiplicity of studies in the last decade), but also antimony to a lower extent. The main contaminant in the extracts was Sb(V), but also elevated concentrations of Sb(III) and TMSb(V) (all in microg L(-1) range). An unidentified Sb compound in the plant extracts was detected, which slightly differ in elution time from TMSb(V). PMID:19269435

Müller, Karsten; Daus, Birgit; Mattusch, Jürgen; Stärk, Hans-Joachim; Wennrich, Rainer

2009-01-15

324

Ecological restoration of mineland with particular reference to the metalliferous mine wasteland in China: A review of research and practice.  

PubMed

Despite a principal contributor to the rapid economic growth, the mining industry in China produced a large amount of wasteland and caused water pollution and soil erosion as well as other environmental damages. In 2002, this industry generated 265.4 Mt tailings, 130.4 Mt gangue and 107.8 Mt smelting slags. The degraded land associated with mining is estimated to be 3.2 Mha by the end of 2004, deteriorating the land shortage of China. Restoration of mine wasteland began in late 1970s but the restoration process was sluggish. The overall restoration rate (the ratio of reclaimed land area to the total degraded land area) of mine wasteland was some 10-12% with a higher rate for coal mine spoils but a lower rate for metal-mined derelict land. From 1994 to 2004, 149 research papers were published about the restoration of China's mining wasteland, of which 70 were on metal-mined land and 61 on the non-metal-mined land. Although 37 institutions in China were involved in the restoration research, only a few remained active and productive. Metal-mined derelict land is often more metal toxic and deficient of macronutrients and is tougher for revegetation. Many substrate amelioration techniques were proposed and tolerant plant species were tested for use of reclamation of the metal-mined tailings. Five hyperaccumulator species have been reported in China for the potential use in phytoremediation. However, these accomplishments were all at laboratory or small-scale field demonstration stage and still far from the practical use in reality. To accelerate the restoration and utilization of mine wasteland, several recommendations are put forward in this review. Above these suggestions, the commitment and efficiency of the government at all levels are vital. PMID:15992864

Li, M S

2005-06-29

325

Mouse HORMAD1 and HORMAD2, Two Conserved Meiotic Chromosomal Proteins, Are Depleted from Synapsed Chromosome Axes with the Help of TRIP13 AAA-ATPase  

PubMed Central

Meiotic crossovers are produced when programmed double-strand breaks (DSBs) are repaired by recombination from homologous chromosomes (homologues). In a wide variety of organisms, meiotic HORMA-domain proteins are required to direct DSB repair towards homologues. This inter-homologue bias is required for efficient homology search, homologue alignment, and crossover formation. HORMA-domain proteins are also implicated in other processes related to crossover formation, including DSB formation, inhibition of promiscuous formation of the synaptonemal complex (SC), and the meiotic prophase checkpoint that monitors both DSB processing and SCs. We examined the behavior of two previously uncharacterized meiosis-specific mouse HORMA-domain proteins—HORMAD1 and HORMAD2—in wild-type mice and in mutants defective in DSB processing or SC formation. HORMADs are preferentially associated with unsynapsed chromosome axes throughout meiotic prophase. We observe a strong negative correlation between SC formation and presence of HORMADs on axes, and a positive correlation between the presumptive sites of high checkpoint-kinase ATR activity and hyper-accumulation of HORMADs on axes. HORMADs are not depleted from chromosomes in mutants that lack SCs. In contrast, DSB formation and DSB repair are not absolutely required for depletion of HORMADs from synapsed axes. A simple interpretation of these findings is that SC formation directly or indirectly promotes depletion of HORMADs from chromosome axes. We also find that TRIP13 protein is required for reciprocal distribution of HORMADs and the SYCP1/SC-component along chromosome axes. Similarities in mouse and budding yeast meiosis suggest that TRIP13/Pch2 proteins have a conserved role in establishing mutually exclusive HORMAD-rich and synapsed chromatin domains in both mouse and yeast. Taken together, our observations raise the possibility that involvement of meiotic HORMA-domain proteins in the regulation of homologue interactions is conserved in mammals.

Roig, Ignasi; Bolcun-Filas, Ewelina; Xu, Huiling; Boonsanay, Verawan; Eckmann, Christian R.; Cooke, Howard J.; Jasin, Maria; Keeney, Scott; McKay, Michael J.; Toth, Attila

2009-01-01

326

Chemical mutagenesis--a promising technique to increase metal concentration and extraction in sunflowers.  

PubMed

Since most of the metal-hyperaccumulating wild plants only produce very low biomass and many high-yielding crops accumulate only moderate amounts of metals, the current research is mainly focused on overcoming these limitations and the optimization of metal phytoextraction. The main goal of the present study was the improvement of metal concentration and extraction properties of Helianthus annuus L by chemical mutagenesis (the non-GMO approach). Sunflowers--hybrid cultivar Salut and inbred lines-were treated with the chemical mutagen ethyl methanesulfonate (EMS). The effect of chemical mutagenesis on metal concentration in and extraction by new sunflower M1 and M2 mutants was directly assessed on a metal-contaminated field in Raft, Switzerland. Mutants of the M2 generation showed a 2-3 times higher metal shoot concentration than the control plants. The best M2 sunflower "giant mutant" 14/185/04 showed a significantly enhanced metal extraction ability: 7.5 times for Cd, 9.2 times for Zn, and 8.2 times for Pb in aboveground parts, as compared to the control plants. Theoretical calculations for the phytoextraction potential of new sunflower variants note that the best sunflower mutant can produce up to 26 t dry matter per hectare and remove 13.3 kg Zn per hectare and year at the sewage sludge contaminated site of Raft; that is a gain factor of 9 compared to Zn extraction by sunflower controls. Furthermore, the use of sunflower oil and biomass for technical purposes (lubricants, biodiesel, biogas) should produce an additional value and improve the economical balance of phytoextraction. PMID:18246722

Nehnevajova, Erika; Herzig, Rolf; Federer, Guido; Erismann, Karl-Hans; Schwitzguébel, Jean-Paul

327

A greenhouse and field-based study to determine the accumulation of arsenic in common homegrown vegetables grown in mining-affected soils.  

PubMed

The uptake of arsenic by plants from contaminated soils presents a health hazard that may affect home gardeners neighboring contaminated environments. A controlled greenhouse study was conducted in parallel with a co-created citizen science program (home garden experiment) to characterize the uptake of arsenic by common homegrown vegetables near the Iron King Mine and Humboldt Smelter Superfund site in southern Arizona. The greenhouse and home garden arsenic soil concentrations varied considerably, ranging from 2.35 to 533 mg kg(-1). In the greenhouse experiment four vegetables were grown in three different soil treatments and in the home garden experiment a total of 63 home garden produce samples were obtained from 19 properties neighboring the site. All vegetables accumulated arsenic in both the greenhouse and home garden experiments, ranging from 0.01 to 23.0 mg kg(-1) dry weight. Bioconcentration factors were determined and show that arsenic uptake decreased in the order: Asteraceae>Brassicaceae>Amaranthaceae>Cucurbitaceae>Liliaceae>Solanaceae>Fabaceae. Certain members of the Asteraceae and Brassicaceae plant families have been previously identified as hyperaccumulator plants, and it can be inferred that members of these families have genetic and physiological capacity to accumulate, translocate, and resist high amounts of metals. Additionally, a significant linear correlation was observed between the amount of arsenic that accumulated in the edible portion of the plant and the arsenic soil concentration for the Asteraceae, Brassicaceae, Amaranthaceae, and Fabaceae families. The results suggest that home gardeners neighboring mining operations or mine tailings with elevated arsenic levels should be made aware that arsenic can accumulate considerably in certain vegetables, and in particular, it is recommended that gardeners limit consumption of vegetables from the Asteraceae and Brassicaceae plant families. PMID:23201696

Ramirez-Andreotta, Monica D; Brusseau, Mark L; Artiola, Janick F; Maier, Raina M

2012-11-29

328

Knocking Out ACR2 Does Not Affect Arsenic Redox Status in Arabidopsis thaliana: Implications for As Detoxification and Accumulation in Plants  

PubMed Central

Many plant species are able to reduce arsenate to arsenite efficiently, which is an important step allowing detoxification of As through either efflux of arsenite or complexation with thiol compounds. It has been suggested that this reduction is catalyzed by ACR2, a plant homologue of the yeast arsenate reductase ScACR2. Silencing of AtACR2 was reported to result in As hyperaccumulation in the shoots of Arabidopsis thaliana. However, no information of the in vivo As speciation has been reported. Here, we investigated the effect of AtACR2 knockout or overexpression on As speciation, arsenite efflux from roots and As accumulation in shoots. T-DNA insertion lines, overexpression lines and wild-type (WT) plants were exposed to different concentrations of arsenate for different periods, and As speciation in plants and arsenite efflux were determined using HPLC-ICP-MS. There were no significant differences in As speciation between different lines, with arsenite accounting for >90% of the total extractable As in both roots and shoots. Arsenite efflux to the external medium represented on average 77% of the arsenate taken up during 6 h exposure, but there were no significant differences between WT and mutants or overexpression lines. Accumulation of As in the shoots was also unaffected by AtACR2 knockout or overexpression. Additionally, after exposure to arsenate, the yeast (Saccharomyces cerevisiae) strain with ScACR2 deleted showed similar As speciation as the WT with arsenite-thiol complexes being the predominant species. Our results suggest the existence of multiple pathways of arsenate reduction in plants and yeast.

Liu, Wenju; Schat, Henk; Bliek, Mathijs; Chen, Yi; McGrath, Steve P.; George, Graham; Salt, David E.; Zhao, Fang-Jie

2012-01-01

329

Functional characterization of AtATM1, AtATM2, and AtATM3, a subfamily of Arabidopsis half-molecule ATP-binding cassette transporters implicated in iron homeostasis.  

PubMed

The functional capabilities of one of the smallest subfamilies of ATP-binding cassette transporters from Arabidopsis thaliana, the AtATMs, are described. Designated AtATM1, AtAATM2, and AtATM3, these half-molecule ABC proteins are homologous to the yeast mitochondrial membrane protein ATM1 (ScATM1), which is clearly implicated in the export of mitochondrially synthesized iron/sulfur clusters. Yeast ATM1-deficient (atm1) mutants grow very slowly (have a petite phenotype), are respiration-deficient, accumulate toxic levels of iron in their mitochondria, and show enhanced compensatory high affinity iron uptake. Of the three Arabidopsis ATMs, AtATM3 bears the closest functional resemblance to ScATM1. Heterologously expressed AtATM3 is not only able to complement the yeast atm1 petite phenotype but is also able to suppress the constitutively high capacity for high affinity iron uptake associated with loss of the chromosomal copy of ScATM1, abrogate intra-mitochondrial iron hyperaccumulation, and restore mitochondrial respiratory function and cytochrome c levels. By comparison, AtATM1 only weakly suppresses the atm1 phenotype, and AtATM2 exerts little or no suppressive action but instead is toxic when expressed in this system. The differences between AtATM3 and AtATM1 are maintained after exchanging their target peptides, and these proteins as well as AtATM2 colocalize with the mitochondrial fluor MitoTracker Red when expressed in yeast as GFP fusions. Although its toxicity when heterologously expressed in yeast, except when fused with GFP, precludes the functional analysis of native AtATM2, a common function, mitochondrial export of Fe/S clusters or their precursors for the assembly of cytosolic Fe/S proteins, is inferred for AtATM3 and AtATM1. PMID:17517886

Chen, Sixue; Sánchez-Fernández, Rocío; Lyver, Elise R; Dancis, Andrew; Rea, Philip A

2007-05-21

330

Cadmium Stress Responses in Brassica juncea: Hints from Proteomics and Metabolomics.  

PubMed

Among heavy metal stressors, cadmium (Cd) pollution is one leading threat to the environment. In this view, research efforts have been increasingly put forward to promote the individuation of phytoextractor plants that are capable of accumulating and withstanding the toxic metals, including Cd, in the aerial parts. We hereby adopted the hyperaccumulator B. juncea (Indian mustard) as a model to investigate plant responses to Cd stress at low (25 ?M) and high (100 ?M) doses. Analytical strategies included mass-spectrometry-based determination of Cd and the assessment of its effect on the leaf proteome and metabolome. Results were thus integrated with routine physiological data. Taken together, physiology results highlighted the deregulation of photosynthesis efficiency, ATP synthesis, reduced transpiration, and the impairment of light-independent carbon fixation reactions. These results were supported at the proteomics level by the observed Cd-dependent alteration of photosystem components and the alteration of metabolic enzymes, including ATP synthase subunits, carbonic anhydrase, and enzymes involved in antioxidant responses (especially glutathione and phytochelatin homeostasis) and the Calvin cycle. Metabolomics results confirmed the alterations of energy-generating metabolic pathways, sulfur-compound metabolism (GSH and PCs), and Calvin cycle. Besides, metabolomics results highlighted the up-regulation of phosphoglycolate, a byproduct of the photorespiration metabolism. This was suggestive of the likely increased photorespiration rate as a means to cope with Cd-induced unbalance in stomatal conductance and deregulation of CO2 homeostasis, which would, in turn, promote CO2 depletion and O2 (and thus oxidative stress) accumulation under prolonged photosynthesis in the leaves from plants exposed to high doses of CdCl2. Overall, it emerges that Cd-stressed B. juncea might rely on photorespiration, an adaptation that would prevent the over-reduction of the photosynthetic electron transport chain and photoinhibition. PMID:24074147

D'Alessandro, Angelo; Taamalli, Manel; Gevi, Federica; Timperio, Anna Maria; Zolla, Lello; Ghnaya, Tahar

2013-10-08

331

The role of plant-associated bacteria in the mobilization and phytoextraction of trace elements in contaminated soils  

PubMed Central

Phytoextraction makes use of trace element-accumulating plants that concentrate the pollutants in their tissues. Pollutants can be then removed by harvesting plants. The success of phytoextraction depends on trace element availability to the roots and the ability of the plant to intercept, take up, and accumulate trace elements in shoots. Current phytoextraction practises either employ hyperaccumulators or fast-growing high biomass plants; the phytoextraction process may be enhanced by soil amendments that increase trace element availability in the soil. This review will focus on the role of plant-associated bacteria to enhance trace element availability in the rhizosphere. We report on the kind of bacteria typically found in association with trace element – tolerating or – accumulating plants and discuss how they can contribute to improve trace element uptake by plants and thus the efficiency and rate of phytoextraction. This enhanced trace element uptake can be attributed to a microbial modification of the absorptive properties of the roots such as increasing the root length and surface area and numbers of root hairs, or by increasing the plant availability of trace elements in the rhizosphere and the subsequent translocation to shoots via beneficial effects on plant growth, trace element complexation and alleviation of phytotoxicity. An analysis of data from literature shows that effects of bacterial inoculation on phytoextraction efficiency are currently inconsistent. Some key processes in plant–bacteria interactions and colonization by inoculated strains still need to be unravelled more in detail to allow full-scale application of bacteria assisted phytoremediation of trace element contaminated soils.

Sessitsch, Angela; Kuffner, Melanie; Kidd, Petra; Vangronsveld, Jaco; Wenzel, Walter W.; Fallmann, Katharina; Puschenreiter, Markus

2013-01-01

332

Cyclin Partners Determine Pho85 Protein Kinase Substrate Specificity In Vitro and In Vivo: Control of Glycogen Biosynthesis by Pcl8 and Pcl10  

PubMed Central

In Saccharomyces cerevisiae, PHO85 encodes a cyclin-dependent protein kinase (Cdk) with multiple roles in cell cycle and metabolic controls. In association with the cyclin Pho80, Pho85 controls acid phosphatase gene expression through phosphorylation of the transcription factor Pho4. Pho85 has also been implicated as a kinase that phosphorylates and negatively regulates glycogen synthase (Gsy2), and deletion of PHO85 causes glycogen overaccumulation. We report that the Pcl8/Pcl10 subgroup of cyclins directs Pho85 to phosphorylate glycogen synthase both in vivo and in vitro. Disruption of PCL8 and PCL10 caused hyperaccumulation of glycogen, activation of glycogen synthase, and a reduction in glycogen synthase kinase activity in vivo. However, unlike pho85 mutants, pcl8 pcl10 cells had normal morphologies, grew on glycerol, and showed proper regulation of acid phosphatase gene expression. In vitro, Pho80-Pho85 complexes effectively phosphorylated Pho4 but had much lower activity toward Gsy2. In contrast, Pcl10-Pho85 complexes phosphorylated Gsy2 at Ser-654 and Thr-667, two physiologically relevant sites, but only poorly phosphorylated Pho4. Thus, both the in vitro and in vivo substrate specificity of Pho85 is determined by the cyclin partner. Mutation of PHO85 suppressed the glycogen storage deficiency of snf1 or glc7-1 mutants in which glycogen synthase is locked in an inactive state. Deletion of PCL8 and PCL10 corrected the deficit in glycogen synthase activity in both the snf1 and glc7-1 mutants, but glycogen synthesis was restored only in the glc7-1 mutant strain. This genetic result suggests an additional role for Pho85 in the negative regulation of glycogen accumulation that is independent of Pcl8 and Pcl10.

Huang, Dongqing; Moffat, Jason; Wilson, Wayne A.; Moore, Lynda; Cheng, Christine; Roach, Peter J.; Andrews, Brenda

1998-01-01

333

Phytoremedial assessment of flora tolerant to heavy metals in the contaminated soils of an abandoned Pb mine in Central Portugal.  

PubMed

Significant accumulation of heavy metals in soils and flora exists around the abandoned Barbadalhos Pb mine in Central Portugal. Soil and plant samples [49 species] were collected from two line transects, LT 1 and LT 2, in the mineralized and non-mineralized area, respectively to gain a comprehensive picture of heavy metals in soils and flora to assess its potential for phytoremediation. Phytosociological inventories of the vegetation were made using the Braun-Blanquet cover-abundance scale. Metal concentrations in soil ranged from (in mg kg(-1)): 98-9330 [Pb], 110-517 [Zn], 7.1-50 [Co], 69-123 [Cr], 31-193 [Cu], 33400-98500 [Fe], 7.7-51 [Ni], 0.95-13 [Ag], 2.8-208 [As], and 71-2220 [Mn] along LT 1; and 24-93 [Pb], 30-162 [Zn], 3.7-34 [Co], 61-196 [Cr], 21-46 [Cu], 24100-59400 [Fe], 17-87 [Ni], 0.71-1.9 [Ag], 4.3-12 [As], and 44-1800 [Mn] along LT 2. Plant metal content ranged from (in mg kg(-1)): 1.11-548 [Pb], 7.06-1020 [Zn], 0.08-2.09 [Co], 0.09-2.03 [Cr], 2.63-38.5 [Cu], 10.4-4450 [Fe], 0.38-8.9 [Ni], and 0.03-1.9 [Ag] along LT 1; and 0.94-11.58 [Pb], 2.83-96.5 [Zn], 0.12-1.44 [Co], 0.21-1.49 [Cr], 1.61-22.7 [Cu], 4.6-2050 [Fe], 0.51-4.81 [Ni], and 0.02-0.31 [Ag] along LT 2. Plants with highest uptake of metals were: Cistus salvifolius (548 mg Pb kg(-1)), Digitalis purpurea (1017 mg Zn kg(-1) and 4450 mg Fe kg(-1)). Mentha suavolens and Ruscus ulmifolius were seen to hyperaccumulate Ag (1.9 and 1 mg Ag kg(-1), respectively). More metals and higher concentrations were traced in plants from LT 1, especially for Pb and Zn. PMID:23098582

Pratas, João; Favas, Paulo J C; D'Souza, Rohan; Varun, Mayank; Paul, Manoj S

2012-10-23

334

Nickel-resistant bacteria from anthropogenically nickel-polluted and naturally nickel-percolated ecosystems.  

PubMed

DNA fragments harboring the nickel resistance determinants from bacteria isolated from anthropogenically polluted ecosystems in Europe and Zaire were compared with those harboring the nickel resistance determinants from bacteria isolated from naturally nickel-percolated soils from New Caledonia by DNA-DNA hybridization. The biotinylated DNA probes were derived from the previously described Alcaligenes eutrophus CH34, Alcaligenes xylosoxidans 31A, Alcaligenes denitrificans 4a-2, and Klebsiella oxytoca CCUG 15788 and four new nickel resistance-determining fragments cloned from strains isolated from soils under nickel-hyperaccumulating trees. Nine probes were hybridized with endonuclease-cleaved plasmid and total DNA samples from 56 nickel-resistant strains. Some of the New Caledonian strains were tentatively identified as Acinetobacter, Pseudomonas mendocina, Comamonas, Hafnia alvei, Burkholderia, Arthrobacter aurescens, and Arthrobacter ramosus strains. The DNA of most strains showed homologies to one or several of the following nickel resistance determinants: the cnr and ncc operons of the strains A. eutrophus CH34 and A. xylosoxidans 31A, respectively, the nre operon of strain 31A, and the nickel resistance determinants of K. oxytoca. On the basis of their hybridization reactions the nickel resistance determinants of the strains could be assigned to four groups: (i) cnr/ncc type, (ii) cnr/ncc/nre type, (iii) K. oxytoca type, and (iv) others. The majority of the strains were assigned to the known groups. Among the strains from Belgium and Zaire, exclusively the cnr/ncc and the cnr/ncc/nre types were found. Among the New Caledonian strains all four types were represented. Homologies to the nre operon were found only in combination with the cnr/ncc operon. The homologies to the cnr/ncc operon were the most abundant and were detected alone or together with homologies to the nre operon. Only the DNA of the strains isolated from soil in Scotland and the United States and that of five of the New Caledonian strains did not show any detectable homologies to any of our probes. The nickel resistance fragment isolated from Burkholderia strain 32W-2 was studied in some detail. This 15-kb BamHI fragment conferred resistance to 1 to 5 mM NiCl(inf2) to Escherichia coli and resistance to up to 25 mM NiCl(inf2) to A. eutrophus. It showed strong homologies to both the cnr/ncc operon and the nre operon and conferred strictly regulated (inducible) nickel resistance to A. eutrophus. PMID:16535048

Stoppel, R; Schlegel, H G

1995-06-01

335

Mapping of fluoride endemic area and assessment of F(-1) accumulation in soil and vegetation.  

PubMed

The prevalence of fluorosis is mainly due to the consumption of more fluoride (F(-1)) through drinking water, vegetables, and crops. The objective of the study was mapping of F(-1) endemic area of Newai Tehsil, Tonk district, Rajasthan, India. For the present study, water, soil (0-45 cm), and vegetation samples were collected from 17 villages. Fluoride concentration in water samples ranged from 0.3 to 9.8 mg/l. Out of 17 villages studied, the amounts of F(-1) content of eight villages were found to exceed the permissible limits. Labile F(-1) content and total F(-1) content in soil samples ranges 11.00-70.05 mg/l and 50.3-179.63 ?g g(-1), respectively. F(-1) content in tree species was found in this order Azadirachta indica 47.32-55.76 ?g g(-1) > Prosopis juliflora 40.16-49.63 ?g g(-1) > Acacia tortilis 34.39-43.60 ?g g(-1). While in case of leafy vegetables, F(-1) content order was Chenopodium album 54.23-98.42 ?g g(-1) > Spinacea oleracea 30.41-64.09 ?g g(-1) > Mentha arvensis 35.48-51.97 ?g g(-1). The order of F(-1) content in crops was found as 41.04 ?g g(-1) Pennisetum glaucum > 13.61 ?g g(-1) Brassica juncea > 7.98 ?g g(-1) Triticum sativum in Krishi Vigyan Kendra (KVK) farms. Among vegetation, the leafy vegetables have more F(-1) content. From the results, it is suggested that the people of KVK farms should avoid the use of highly F(-1) containing water for irrigation and drinking purpose. It has been recommended to the government authority to take serious steps to supply drinking water with low F(-1) concentration for the fluorosis affected villages. Further, grow more F(-1) hyperaccumulator plants in F(-1) endemic areas to lower the F(-1) content of the soils. PMID:22638723

Saini, Poonam; Khan, Suphiya; Baunthiyal, Mamta; Sharma, Vinay

2012-05-26

336

Environmental hazards of aluminum to plants, invertebrates, fish, and wildlife  

USGS Publications Warehouse

Aluminum is extremely common throughout the world and is innocuous under circumneutral or alkaline conditions. However, in acidic environments, it can be a maJor limiting factor to many plants and aquatic organisms. The greatest concern for toxicity in North America occurs in areas that are affected by wet and dry acid deposition, such as eastern Canada and the northeastern U.S. Acid mine drainage, logging, and water treatment plant effluents containing alum can be other maJor sources of Al. In solution, the metal can combine with several different agents to affect toxicity. In general, Al hydroxides and monomeric Al are the most toxic forms. Dissolved organic carbons, F, PO(3)3- and SO(4)2- ameliorate toxicity by reducing bioavailability. Elevated metal levels in water and soil can cause serious problems for some plants. Algae tend to be both acid- and Al tolerant and, although some species may disappear with reduced pH, overall algae productivity and biomass are seldom affected if pH is above 3.0. Aluminum and acid toxicity tend to be additive to some algae when pH is less than 4.5. Because the metal binds with inorganic P, it may reduce P availability and reduce productivity. Forest die-backs in North America involving red spruce, Fraser fir, balsam fir, loblolly pine, slash pine, and sugar maples have been ascribed to Al toxicity, and extensive areas of European forests have died because of the combination of high soil Al and low pH. Extensive research on crops has produced Al-resistant cultivars and considerable knowledge about mechanisms of and defenses against toxicity. Very low Al levels may benefit some plants, although the metal is not recognized as an essential nutrient. Hyperaccumulator species of plants may concentrate Al to levels that are toxic to herbivores. Toxicity in aquatic invertebrates is also acid dependent. Taxa such as Ephemeroptera, Plecoptera, and Cladocera are sensitive and may perish when Al is less than 1 mg.L-1 whereas dipterans, molluscs, and isopods seem to be tolerant. In Al-sensitive species, elevated levels (approximately 500 micrograms.L-1) affect ion regulation and respiratory efficiency. Toxicity tends to be greatest near a species` threshold of pH sensitivity. At lower pHs, Al may have a slight ameliorative effect by interfering with H+ transport across membranes. Aquatic invertebrates can accumulate very high levels of Al, but most of this appears to be through adsorption rather than assimilation. Aluminum concentrations may be as high as 5000 mg.kg-1 in insects and greater than 17,000 mg.kg-1 in other invertebrates.

Sparling, D.W.; Lowe, T.P.

1996-01-01

337

Ctr2 is partially localized to the plasma membrane and stimulates copper uptake in COS-7 cells.  

PubMed

Ctr1 (copper transporter 1) mediates high-affinity copper uptake. Ctr2 (copper transporter 2) shares sequence similarity with Ctr1, yet its function in mammalian cells is poorly understood. In African green monkey kidney COS-7 cells and rat tissues, Ctr2 migrated as a predominant band of approximately 70 kDa and was most abundantly expressed in placenta and heart. A transiently expressed hCtr2-GFP (human Ctr2-green fluorescent protein) fusion protein and the endogenous Ctr2 in COS-7 cells were mainly localized to the outer membrane of cytoplasmic vesicles, but were also detected at the plasma membrane. Biotinylation of Ctr2 with the membrane-impermeant reagent sulfo-NHS-SS-biotin [sulfosuccinimidyl-2-(biotinamido)ethyl-1,3-dithiopropionate] confirmed localization at the cell surface. Cells expressing hCtr2-GFP hyperaccumulated copper when incubated in medium supplemented with 10 microM CuSO(4), whereas cells depleted of endogenous Ctr2 by siRNAs (small interfering RNAs) accumulated lower levels of copper. hCtr2-GFP expression did not affect copper efflux, suggesting that hCtr2-GFP increased cellular copper concentrations by promoting uptake at the cell surface. Kinetic analyses showed that hCtr2-GFP stimulated saturable copper uptake with a K(m) of 11.0+/-2.5 microM and a K(0.5) of 6.9+/-0.7 microM when data were fitted to a rectangular hyperbola or Hill equation respectively. Competition experiments revealed that silver completely inhibited hCtr2-GFP-dependent copper uptake, whereas zinc, iron and manganese had no effect on uptake. Furthermore, increased copper concentrations in hCtr2-GFP-expressing cells were inversely correlated with copper chaperone for Cu/Zn superoxide dismutase protein expression. Collectively, these results suggest that Ctr2 promotes copper uptake at the plasma membrane and plays a role in regulating copper levels in COS-7 cells. PMID:17944601

Bertinato, Jesse; Swist, Eleonora; Plouffe, Louise J; Brooks, Stephen P J; L'abbé, Mary R

2008-02-01

338

The effects of soil type and chemical treatment on nickel speciation in refinery enriched soils: A multi-technique investigation  

NASA Astrophysics Data System (ADS)

Aerial deposition of Ni from a refinery in Port Colborne, Ontario, Canada has resulted in the enrichment of 29 km 2 of land with Ni concentrations exceeding the Canadian Ministry of the Environment's remedial action level of 200 mg kg -1. Several studies on these soils have shown that making the soils calcareous was effective at reducing chemically extractable Ni, as well as alleviating Ni phytotoxicity symptoms in vegetable crops grown in the vicinity of the refinery. Conversely, dolomitic limestone additions resulted in increased uptake of Ni in the Ni hyperaccumulator Alyssum murale 'Kotodesh', a plant whose use was proposed as a remediation strategy for this area. In this paper we use multiple techniques to directly assess the role soil type and lime treatments play in altering the speciation of Ni in the Welland loam and Quarry muck soils around the refinery and relate these findings to Ni mobility and bioavailability. Stirred-flow dissolution experiments using pH 4 HNO 3 showed that Ni release from the limed Quarry muck and Welland loam soils was reduced (˜0.10%) relative to the unlimed soils (˜2.0%). Electron microprobe analysis (EMPA) identified approximately spherical NiO and Ni metal particles, which are associated with no other metals, and range from 5 to 50 ?m in diameter. Synchrotron micro-X-ray absorption fine structure and X-ray fluorescence spectroscopies showed that Ni and Al layered double hydroxide (Ni-Al LDH) phases were present in both the limed and unlimed mineral soils, with a tendency towards more stable (e.g., aged-LDH and phyllosilicate) Ni species in the limed soil, possibly aided by the solubilization of Si with increasing pH. In the muck soils, Ni-organic complexes (namely fulvic acid) dominated the speciation in both limed and unlimed soils. The results reported herein show that both soil type and treatment have a pronounced effect on the speciation of Ni in the soils surrounding the Port Colborne refinery. We provide the first evidence that Ni-Al LDH phases can form in anthropogenically enriched mineral field soils at circumneutral pH, and can lead to a reduction in Ni mobility. In the organic soils Ni is strongly complexed by soil organic matter; a property enhanced with liming. Interestingly, increased accumulation of Ni by A. murale grown in the limed muck and loam soils indicates that the plant may be capable of removing Ni from those fractions typically considered unavailable to most plants.

McNear, David H.; Chaney, Rufus L.; Sparks, Donald L.

2007-05-01

339

Potential of MuS1 Transgenic Tobacco for Phytoremediation of the Urban Soils Contaminated with Cadmium  

NASA Astrophysics Data System (ADS)

Urban soils are prone to contamination by trace elements such as Cd, Cu, Pb and Zn. Phytoremediation is one of the attractive remediation methods for soils contaminated with trace elements due to its non-destructive and environmentally-friendly characteristic. Scientists have tried to find hyper-accumulator plants in nature or to develop transgenic plant through genetic engineering. This study was carried out to identify a potential of MuS1 transgenic tobacco for phytoremediation of the urban soils contaminated with Cd. MuS1 is known as a multiple stress related gene with several lines. The previous study using RT-PCR showed that the expression of MuS1 gene in tobacco plant induced tolerance to Cd stress. For this study, MuS1 transgenic tobacco and wild-type tobacco (control) were cultivated in a hydroponic system treated with Cd (0, 50, 100 and 200?M Cd) for 3 weeks. At harvest, both tobacco and nutrient solution were collected and were analyzed for Cd. Effect of Cd treatment on morphological change of the tobacco leaves was also observed by variable-pressure scanning electron microscopy (VP-SEM). The tolerance of MuS1 transgenic tobacco to Cd stress was better than that of wild-type tobacco at all Cd levels. Especially, wild-type tobacco showed chlorosis and withering with 200?M Cd treatment, whereas MuS1 transgenic tobacco gradually recovered from Cd damage. Wild-type tobacco accumulated more Cd (4.65mg per plant) than MuS1 transgenic tobacco (2.37mg per plant) with 200?M Cd treatment. Cd translocation rate from root to leaves was 81.8 % for wild-type tobacco compared to 37.1 % for MuS1 transgenic tobacco. Result of VP-SEM showed that the number of trichome in the leaves for wild-type tobacco increased in comparison with that for untreated samples after 3 weeks, while that for MuS1 transgenic tobacco was not changed by Cd treatment. Results showed that the mechanism of the recovery of the MuS1 tobacco plant was not by high level of Cd uptake and accumulation in the plant but by revealing resistance to Cd through inducing less Cd uptake and/or more Cd immobilization around roots, resulting in less translocation to shoot. In conclusion, this study showed a potential to use MuS1 transgenic tobacco for phytoremediation of the urban soils contaminated with Cd.

Kim, K. H.; Kim, Y. N.; Kim, S. H.

2010-05-01

340

Phytoremediation of soils contaminated by cadmium  

NASA Astrophysics Data System (ADS)

Phytoremediation is a technique to clean up soils contaminated with heavy metals. Advantages of this method are that (1) This technique is suitable to cleanup soils slightly contaminated with heavy metals in relatively wide area. (2) The expense for clean up is lower than civil engineering techniques. (3) This method can remove heavy metals fundamentally from contaminated. (4) The heavy metals are able to recycle by ashing of plants. Many researches have been done on the phytoremediation up to now, but almost all these researches were devoted to clarify the phytoremediation from the view point of plants themselves. However, few efforts have been devoted to analyze the migrations of heavy metals in soils during the phytoremediation process. The objective of this study is to clarify the features of Cd migration when plant roots are absorbing Cd from the ambient soils. Especially, we focused on finding the Cd migration pattern by changing the soil condition such as plant growing periods, planting densities, and the initial Cd concentration in soils. We planted sunflowers in columns filled with Cd contaminated soils because sunflower is a well-known hyperaccumulator of Cd from soils. By cutting the shoots of plants at the soil surface, and by keeping the plant roots in the soils without disturbance, the Cd concentrations, moisture contents, pH distributions, EC distributions, and dry weight of residual roots in the soils were carefully analyzed. The experimental results showed that (1)The growth of the planted sunflowers were suffered by applying of Cd. (2)The decrease of suction was affected by water uptake by roots at the depth from 0 to 5 cm. Water contents with plants in soils decrease more than without plants. (3)Cd adsorption by roots was predominant within 5cm from soil surface. In addition, it was also shown that there was an optimal Cd concentration where Cd is most effectively adsorbed by the plant. In this experiment we found that 40 to 60 mg kg-1 was the optimal concentration. By a trial calculation, it was revealed that more than 30 times of planting-cultivating processes were needed to decrease the Cd concentration from 9.75 to 0.4 mg Cd kg-1. When the sunflower was not planted, Cd did not move in the soils even when the soil water the sunflower was planted, Cd in the soil moved toward the plant roots associating with the water uptake by the roots. This Cd movement may have enhanced by the secretion of organic acid from plant roots.

Watai, H.; Miyazaki, T.; Fujikawa, T.; Mizoguchi, M.

2004-12-01

341

A greenhouse study on arsenic remediation potential of Vetiver grass (Vetiveria Zizanioides) as a function of soil physico-chemical properties  

NASA Astrophysics Data System (ADS)

Arsenic is one of the most harmful and toxic metals, being a Group A human carcinogen. Mining activities as well as the use of arsenic-containing pesticides have resulted in the contamination of a wide variety of sites including mine tailings, cattle dip sites, wood treatment sites, pesticide treatment areas, golf courses, etc. Phytoremediation has emerged as a novel and promising technology, which uses plants to clean up contaminated soil and water taking advantage of plant's natural abilities to extract and accumulate various contaminants. This method has distinct advantages, since it maintains the biological properties and physical structure of the soil, is environment friendly, and above all, inexpensive. However, effective remediation of contaminated residential soils using a specific plant species is an immensely complex task whose success depends on a multitude of factors including the ability of the target plant to uptake, translocate, detoxify, and accumulate arsenic in its system. One of the major challenges in phytoremediation lies in identifying a fast- growing, high biomass plant that can accumulate the contaminant in its harvestable parts. vetiver grass (Vetiveria zizanioides) is a fast-growing perennial grass with strong ecological adaptability and large biomass. While this plant is not a hyperaccumulator of arsenic, it has been reported to be able to tolerate and accumulate considerable amounts of arsenic. Being a high biomass, fast-growing plant, vetiver has the potential to be used for arsenic remediation. The present study investigates the potential of vetiver grass to tolerate and accumulate arsenic in soils with varying physico-chemical properties. A greenhouse study is in progress to study the uptake, tolerance and stress response of vetiver grass to inorganic arsenical pesticide. A column study was set up using 5 soils (Eufaula, Millhopper, Orelia, Orla, and Pahokee Muck) contaminated with sodium arsenite at 4 different concentrations of arsenic (0, 45, 225 and 450 mgAs/kg soil). Vetiver plants were grown for a period of 4 months, harvested at two time periods (2 months and 4 months). Plant biomass, shoot and root lengths, arsenic accumulation in roots and shoots were measured. Total and exchangeable arsenic was correlated with phyto-extracted arsenic. In addition, 3 important antioxidant enzyme activities were measured in root and shoot tissues, viz., Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidases (GPx) to evaluate the effect of arsenic stress on vetiver plants. This study will provide information on the capability of vetiver grass to remediate sites contaminated with arsenic as a function of soil physico- chemical properties.

Quispe, M. A.; Datta, R.; Sarkar, D.; Sharma, S.

2006-05-01

342

Cadmium uptake, chemical forms, subcellular distribution, and accumulation in Echinodorus osiris Rataj.  

PubMed

Phytoremediation is a technology for extracting or inactivating pollutants in soil. Echinodorus osiris (E. osiris) is a fast growing perennial wetland plant that is common in tropical and subtropical areas and has a high tolerance to cadmium (Cd). However, the absorption dynamics, subcellular distribution and accumulation of Cd by E. osiris had not been investigated. In this paper, hydroponic experiments with different levels of Cd(2+) (0, 5.0, 15.0 mg L(-1)) were carried out to determine these characteristics of E. osiris. The results indicated that the Cd absorption rate of Echinodorus osiris decreased over time, and the absorption rate within 0.5-1.0 h was faster than after 1.0 h. In a 6.0 hour time period, the rate of Cd uptake fit a quadratic polynomial curve when E. osiris was grown under the 5 mg L(-1) Cd treatment. However, the rate of Cd uptake by E. osiris fit a cubic polynomial model with the 15 mg L(-1) Cd treatment. In the roots, the ethanol-extractable Cd, water-extractable Cd, and NaCl-extractable Cd were the largest proportions of the total Cd. The HAc-extractable Cd, HCl-extractable Cd, and residual-Cd represented a larger proportion of the total Cd in the leaves which was combined with phosphate including CdHPO4, Cd3 (PO4)2, and oxalic acid. When analyzing the subcellular distribution of Cd in the plant, the soluble fraction containing Cd accounted for the largest part (69.49-88.39%) followed by the Cd bound to the cell wall (8.44-25.62%). Both the lower and the higher Cd treatments demonstrated that compartmentation by the vacuole and cell wall binding were two effective defense mechanisms of the plant. However, the vacuole became the main site for Cd accumulation in the leaves under the 15 mg L(-1) Cd treatment. E. osiris was able to accumulate high concentrations of Cd in both the roots and the leaves. The Cd concentration reached 502.97 mg kg(-1) and 2742.95 mg kg(-1) in the shoots and roots, respectively, after 27 days of cultivation. It was concluded that E. osiris is a potential hyperaccumulator of Cd. PMID:23764771

Zhang, Chaolan; Zhang, Peng; Mo, Chuangrong; Yang, Weiwei; Li, Qinfeng; Pan, Liping; Lee, D K

2013-07-01

343

Heavy Metal Uptake, Translocation, and Bioaccumulation Studies of Triticum aestivum Cultivated in Contaminated Dredged Materials  

PubMed Central

Phytoremediation is a technology that uses vegetation to remediate contaminants from water, soil, and sediments. Unlike traditional remediation techniques such as soil washing or vitrification, phytoremediation offers a technology that is solar-driven, aesthetically pleasing, and cost effective. Recent studies indicate that winter wheat (Triticum aestivum L.) is a potential accumulator for heavy metals such as lead (Pb) and cadmium (Cd) in hydroponic systems. Based on these findings, a laboratory study was conducted with the primary objective of determining the phytoaccumulation capability of this plant species for heavy metals from contaminated dredged materials (DMs) originating from two confined disposal facilities (CDF). The United States Army Corps of Engineers (USACE) manages several hundred million cubic meters of DMs each year, and 5 to 10 % of these DMs require special handling because they are contaminated with hazardous substances that can move from the substrates into food webs causing unacceptable risk outside CDFs. Phytoremediation may offer an alternative to decrease this risk. Chemical analyses by USACE personnel identified 17 metals in various DMs, but in this present study, only zinc (Zn) and Cd were investigated. Pre-germinated seeds of the test plants were planted under laboratory conditions in pots containing the various DMs and reference soil. Four weeks after planting, plants were harvested and separated into roots and shoots for biomass production and tissue metal concentrations analyses. Results showed that T. aestivum plants have the capacity to tolerate and grow in multiple-metal contaminated DMs with the potential of accumulating various amounts of Zn and Cd. Root and shoot biomass of T. aestivum were not significantly affected by the DMs on which the plants were grown suggesting that this plant species can grow just as well on DMs contaminated by various metals as in the reference soil. No significant differences in the Zn tissue concentrations were observed, differences in Cd tissue concentrations were noted. A maximum concentration of 26 mg Cd kg?1 DW was detected in T. aestivum shoots. Although Cd tissue concentrations of T. aestivum plants in this study were below the Cd plant hyperaccumulation criterion of >100 mg kg?1 Cd found in other studies, this plant species however may still have beneficial uses for phytoremediation studies. T. aestivum plants may serve as an indicator plant for environmental assessment and management, in which the concentration of heavy metals (e.g. Cd) mirrors the concentration in the substrate without dying due to phytotoxicity at low metal concentrations.

Shumaker, Ketia L.; Begonia, Gregorio

2005-01-01

344

Arsenic Accumulation by Pteris vittata L. in Two Chemically Variant Soils Treated with Arsenical Pesticides - Greenhouse Study  

NASA Astrophysics Data System (ADS)

Arsenic (As) is one of the most toxic elements present in the environment. Over the years, arsenic has found its way to the environment due to its extensive use in agriculture and in industrial practices as pesticides, fertilizers, wood preservatives, smelter wastes and coal combustion ash, all of which are of great environmental concern. Arsenic contamination affects biological activities because it is a carcinogen and a mutagen, which has detrimental effects on the immune system of animals. Remediation of arsenic-contaminated soils has become a major environmental issue in the recent years. Several physical and chemical treatment methods, such as soil washing, co-precipitation, and excavation, have used to remediate As, but all of these methods are rather expensive and can disturb soil physiology and ecology. Phytoremediation, a plant based technology for the removal of toxic contaminants from soil and water is an attractive approach. Of late, this technology has received a high degree of attention from the scientific community because it is environment-friendly and also because of its tremendous cost efficiency compared to the conventional methods. Chinese Brake Fern (Pteris vittata L.) is a known arsenic hyperaccumulator that is being used extensively at present to remove As from soils. However, the degree of efficiency of this plant in accumulating As is likely to be a function of the soil properties. The objective of the reported study was to investigate arsenic uptake by Chinese Brake Fern in As-contaminated soils from the Immokalee (acid sand with minimal As-retention potential) and Millhopper series (sandy loam with high Fe/Al content, hence, high As-retention potential). A greenhouse experiment was designed to evaluate the effects on As uptake by Chinese Brake Fern at two pesticide application rates: 225 mg/kg and 500 mg/kg As in two chemical forms, namely sodium arsenate (AsV) and dimethylarsinic acid (DMA). Each treatment was replicated three times in separate columns. The leaf tissues were collected at time-intermediate (3 months) and at time-final (6 months, when root tissues were also collected) to measure As accumulation after acid-digesting the plants, followed by metal analysis using a graphite furnace atomic absorption spectrophotometer. Plant biomass was monitored for potential growth inhibition. Results showed that As accumulation in shoot was much higher root in both Millhopper and Immokalee soils. Higher As concentrations in plant tissues were observed at the higher application rate treatments in both soils for both arsenate and DMA. However, plant biomass decreased at high As concentration. The results indicate possible biochemical mechanisms in Chinese Brake Fern that enhance As uptake and its translocation from root to shoot.

Therapong, C.; Datta, R.; Sarkar, D.; Pachanoor, D.

2006-05-01

345

Cationic amphiphilic drugs cause a marked expansion of apparent lysosomal volume: Implications for an intracellular distribution-based drug interaction  

PubMed Central

How a drug distributes within highly compartmentalized mammalian cells can affect both the activity and pharmacokinetic behavior. Many commercially available drugs are considered to be lysosomotropic, meaning they are extensively sequestered in lysosomes by an ion trapping-type mechanism. Lysosomotropic drugs typically have a very large apparent volume of distribution and a prolonged half-life in vivo, despite minimal association with adipose tissue. In this report we tested the prediction that the accumulation of one drug (perpetrator) in lysosomes could influence the accumulation of a secondarily administered one (victim), resulting in an intracellular distribution-based drug interaction. To test this hypothesis cells were exposed to nine different hydrophobic amine-containing drugs, which included imipramine, chlorpromazine and amiodarone, at a 10 µM concentration for 24 to 48 hours. After exposure to the perpetrators the cellular accumulation of LysoTracker Red (LTR), a model lysosomotropic probe, was evaluated both quantitatively and microscopically. We found that all of the tested perpetrators caused a significant increase in the cellular accumulation of LTR. Exposure of cells to imipramine caused an increase in the cellular accumulation of other lysosomotropic probes and drugs including LyosTracker Green, daunorubicin, propranolol and methylamine; however, imipramine did not alter the cellular accumulation of non-lysosomotropic amine-containing molecules including MitoTracker Red and sulforhodamine 101. In studies using ionophores to abolish intracellular pH gradients we were able to resolve ion trapping-based cellular accumulation from residual pH-gradient independent accumulation. Results from these evaluations in conjunction with lysosomal pH measurements enabled us to estimate the relative aqueous volume of lysosomes of cells before and after imipramine treatment. Our results suggest that imipramine exposure caused a 4-fold expansion in the lysosomal volume, which provides the basis for the observed drug interaction. The imipramine-induced lysosomal volume expansion was shown to be both time- and temperature-dependent and reversed by exposing cells to hydroxypropyl-?-cyclodextrin, which reduced lysosomal cholesterol burden. This suggests that the expansion of lysosomal volume occurs secondary to perpetrator-induced elevations in lysosomal cholesterol content. In support of this claim, the cellular accumulation of LTR was shown to be higher in cells isolated from patients with Niemann-Pick Type C disease, which are known to hyper-accumulate cholesterol in lysosomes.

Funk, Ryan S.; Krise, Jeffrey P.

2012-01-01

346

Exposure and bioavailability of arsenic in contaminated soils from the La Parrilla mine, Spain  

NASA Astrophysics Data System (ADS)

Arsenic derived from mining activity may contaminate water, soil and plant ecosystems resulting in human health and ecotoxicological risks. In this study, exposure assessment of arsenic (As) in soil, spoil, pondwater and plants collected from the areas contaminated by mine tailings and spoils in and around the La Parrilla mine, Caceres province, Spain, was carried out using AAS method. Water solubility, bioavailability and soil-plant transfer coefficients of As and phytoremediation potential of plants were determined. Arsenic concentrations varied from 148 to 2,540 mg/kg in soils of site 1 and from 610 to 1,285 mg/kg in site 2 exceeding the guideline limit for agricultural soil (50 mg/kg). Arsenic concentrations in pond waters varied from 8.8 to 101.4 ?g/l. High concentrations of water-soluble As in the soils that ranged from 0.10 to 4.71 mg/kg in site 1 and from 0.46 to 4.75 mg/kg in site 2 exceeded the maximum permitted level of water-soluble As (0.04 mg/kg) in agricultural soils. Arsenic concentrations varied from 0.8 to 149.5 mg/kg dry wt in the plants of site 1 and from 2.0 to 10.0 mg/kg in the plants of site 2. Arsenic concentrations in plants increased in the approximate order: Retama sphaerocarpa < Pteridium aquilinum < Erica australis < Juncus effusus < Phalaris caerulescens < Spergula arvensis in site 1. The soil-plant transfer coefficients for As ranged from 0.001 to 0.21 in site 1 and from 0.004 to 0.016 in site 2. The bioconcentration factor based on water-soluble As of soil varied from 3.2 to 593.9 in the plants of site 1 whereas it varied from 2.1 to 20.7 in the plants of site 2. To our knowledge, this is the first study in Europe to report that the fern species P. aquilinum accumulates extremely low contents of As in its fronds despite high As levels in the soils. Therefore, the S. arvensis, P. caerulescens and J. effusus plant species grown in this area might be used to partly remove the bioavailable toxic As for the purpose of minimization of mining impacts until hypothetical hyperaccumulating and/or transgenic plants could be transplanted for the phytoremediation of As contaminated soils.

Anawar, H. M.; Garcia-Sanchez, A.; Murciego, A.; Buyolo, T.

2006-05-01

347

Cationic amphiphilic drugs cause a marked expansion of apparent lysosomal volume: implications for an intracellular distribution-based drug interaction.  

PubMed

How a drug distributes within highly compartmentalized mammalian cells can affect both the activity and pharmacokinetic behavior. Many commercially available drugs are considered to be lysosomotropic, meaning they are extensively sequestered in lysosomes by an ion trapping-type mechanism. Lysosomotropic drugs typically have a very large apparent volume of distribution and a prolonged half-life in vivo, despite minimal association with adipose tissue. In this report we tested the prediction that the accumulation of one drug (perpetrator) in lysosomes could influence the accumulation of a secondarily administered one (victim), resulting in an intracellular distribution-based drug interaction. To test this hypothesis cells were exposed to nine different hydrophobic amine-containing drugs, which included imipramine, chlorpromazine and amiodarone, at a 10 ?M concentration for 24 to 48 h. After exposure to the perpetrators the cellular accumulation of LysoTracker Red (LTR), a model lysosomotropic probe, was evaluated both quantitatively and microscopically. We found that all of the tested perpetrators caused a significant increase in the cellular accumulation of LTR. Exposure of cells to imipramine caused an increase in the cellular accumulation of other lysosomotropic probes and drugs including LyosTracker Green, daunorubicin, propranolol and methylamine; however, imipramine did not alter the cellular accumulation of non-lysosomotropic amine-containing molecules including MitoTracker Red and sulforhodamine 101. In studies using ionophores to abolish intracellular pH gradients we were able to resolve ion trapping-based cellular accumulation from residual pH-gradient independent accumulation. Results from these evaluations in conjunction with lysosomal pH measurements enabled us to estimate the relative aqueous volume of lysosomes of cells before and after imipramine treatment. Our results suggest that imipramine exposure caused a 4-fold expansion in the lysosomal volume, which provides the basis for the observed drug interaction. The imipramine-induced lysosomal volume expansion was shown to be both time- and temperature-dependent and reversed by exposing cells to hydroxypropyl-?-cyclodextrin, which reduced lysosomal cholesterol burden. This suggests that the expansion of lysosomal volume occurs secondary to perpetrator-induced elevations in lysosomal cholesterol content. In support of this claim, the cellular accumulation of LTR was shown to be higher in cells isolated from patients with Niemann-Pick type C disease, which are known to hyperaccumulate cholesterol in lysosomes. PMID:22449202

Funk, Ryan S; Krise, Jeffrey P

2012-04-06

348

Influence of fertilization on the capability of rice resistance to diseases  

NASA Astrophysics Data System (ADS)

Organic cultivation of rice requires no use of any agricultural chemicals during the entire period of growth, and so the rice's self-prevention of diseases and pests is vitally important. A field experiment was carried out to study the possible influence of different fertilization on the capability of rice resistance to diseases and pests. A rice variety used for this experiment is Jia-He 218. Four treatments (A, B, C and D) were designed: A is a control, without using any fertilizers; B, after manuring of green azolla, 0.67 kg/m2; C, after manuring of rapeseed cake, 0.30 kg/m2; D, after fertilizing of ammonium bicarbonate, 0.025 kg/m2, and urea, 0.025 kg/m2. The experiment plot is 66.7 m2, with three replicates. The results indicated that the fertilization patterns significantly influence the growth of rice seedlings: The heights by A, B, C and D are 37 cm, 40 cm , 42 cm and 45 cm on average, respectively; the spike numbers, 45, 65, 73 and 75, respectively; chlorophyll contents in leaves, 1.84 mg/g, 2.42 mg/g, 3.02 mg/g and 3.97 mg/g, respectively. The rice with the different fertilization also varies in nutrient concentration in leaves: NH4-N concentration in leaves by A, B, C and D is 47.5 mg/kg, 61.1 mg/kg, 74.7 mg/kg and 135.8 mg/kg on average, respectively; NO3-N in leaves, 138.9 mg/kg, 185.2 mg/kg, 154.3 mg/kg and 293.2 mg/kg, respectively. The fertilization patterns, moreover, show a significant influence on the incidence of diseases and pests to rice seedlings: The incidence of rice cnaphalocrocis medinalis by A, B, C and D is 1.33 %, 1.50 %, 1.75 % and 89.0 % on average, respectively; that of bacterial leaf blight, 0, 1.25 %, 1.75 % and 85.0 %, respectively; number of rice planthopper in each plant, 20, 21, 21 and 30, respectively. As a result, the yield of rice grain by A, B, C and D is 4540 kg/ha, 4606 kg/ha, 4503 kg/ha and 4092 kg/ha on average, respectively. In conclusion, the rice seedlings treated with chemical fertilizers grow large and tender, which makes it more vulnerable to diseases and pests, resulting in low grain yield. In addition, its immune system capability might be significantly reduced by hyper-accumulation of free nutrients in leaves or stems due to excessive application of chemical fertilizers, and thus leaving it more seriously attacked by diseases and pests.

Hu, Xue-Feng; Chang, Yue-Ya; Jiang, Ying; Yan, Xiao-Juan; Luo, Fan

2013-04-01

349

Phyto extraction and accumulation of mercury in selected plant species grown in soil contaminated with different mercury compounds  

SciTech Connect

The objective of our research is to screen and search for suitable plant species for phyto-remediation of mercury-contaminated soil. Currently our effort is specifically focused on mercury removal from the U.S. Department of Energy's (DOE) Oak Ridge Site, where mercury contamination is a major concern in the Y-12 Watershed area. In order to cost effectively implement those remediation efforts currently planned for FY09, it is necessary now to obtain an improved understanding of biological means of removing mercury and mercury compounds from the Oak Ridge ecosystem. Phyto-remediation is a technology that uses various plants to degrade, extract, contain, or immobilize contaminants from soil and water. In particular, phyto-extraction is the uptake of contaminants by plant roots and translocation within the plants to shoots or leaves. Contaminants are generally removed by harvesting the plants. We have investigated phyto-extraction of mercury from contaminated soil by using some of the known metal accumulating wild plants since no natural plant species with mercury hyper-accumulating properties has yet been identified. Different natural plant species have been studied for mercury uptake, accumulation, toxicity and overall mercury removal efficiency. Various mercury compounds, such as HgS, HgCl{sub 2} and Hg(NO{sub 3}){sub 2}, were used as contaminant sources. Different types of soil were examined and chosen for phyto-remediation experiments. We have applied microscopy and diffuse reflectance spectrometry as well as conventional analytical chemistry to monitor the phyto-remediation processes of mercury uptake, translocation and accumulation; and the physiological impact of mercury contaminants on selected plant species. Our results indicate that certain plant species, such as beard grass (Polypogon monospeliensis), accumulated a very limited amount of mercury in the shoots (<65 mg/kg), even though root mercury accumulation is significant (maximum 2298 mg/kg). Consequently, this plant species may not be suitable for mercury phyto-remediation. Other plant species, such as Indian mustard (Brassica juncea), a well-studied metal accumulator, exhibited severe chlorosis symptoms during some experiments. Among all the plant species studied, Chinese brake fern (Pteris vittata) accumulated significant amount of mercury in both roots and shoots and hence may be considered as a potential candidate for mercury phyto-extraction. During one experiment, brake ferns accumulated 540 mg/kg and 1469 mg/kg in shoots after 18 days of growing in soils treated with 500 ppm and 1000 ppm HgCl{sub 2} powder, respectively; no visual stress symptoms were observed. We also studied mercury phyto-remediation using aged soils that contaminated HgS, HgCl{sub 2}, and Hg(NO{sub 3}){sub 2}. We have found that up to hundreds of ppm mercury can be accumulated in the roots of Indian mustard plants grown with soil contaminated by mercury sulfide; HgS is assumed to be the most stable and also the predominant mercury form in Oak Ridge flood plain soils. We have also started to investigate different mercury uptake mechanisms, such as root uptake of soil contaminant and foliar mercury accumulation from ambient air. (authors)

Su, Y.; Han, F.; Shiyab, S.; Monts, D.L. [Mississippi State Univ., Institute for Clean Energy Technology (ICET), Starkville, MS (United States)

2007-07-01

350

Accumulation of mercury in selected plant species grown in soils contaminated with different mercury compounds  

SciTech Connect

The objective of our research is to screen and search for suitable plant species for phyto-remediation of mercury-contaminated soil. Currently our effort is specifically focused on mercury removal from the U.S. Department of Energy (DOE) sites, where mercury contamination is a major concern. In order to cost effectively implement mercury remediation efforts, it is necessary now to obtain an improved understanding of biological means of removing mercury and mercury compounds.. Phyto-remediation is a technology that uses various plants to degrade, extract, contain, or immobilize contaminants from soil and water. In particular, phyto-extraction is the uptake of contaminants by plant roots and translocation within the plants to shoots or leaves. Contaminants are generally removed by harvesting the plants. We have investigated phyto-extraction of mercury from contaminated soil by using some of the known metal-accumulating plants since no natural plant species with mercury hyper-accumulating properties has yet been identified. Different natural plant species have been studied for mercury uptake, accumulation, toxicity and overall mercury removal efficiency. Various mercury compounds, such as HgS, HgCl{sub 2}, and Hg(NO{sub 3}){sub 2}, were used as contaminant sources. Different types of soil were examined and chosen for phyto-remediation experiments. We have applied microscopy and diffuse reflectance spectrometry as well as conventional analytical chemistry to monitor the phyto-remediation processes of mercury uptake, translocation and accumulation, and the physiological impact of mercury contaminants on selected plant species. Our results indicate that certain plant species, such as beard grass (Polypogon monospeliensis), accumulated a very limited amount of mercury in the shoots (<65 mg/kg), even though root mercury accumulation is significant (maximum 2298 mg/kg). Consequently, this plant species may not be suitable for mercury phyto-remediation. Other plant species, such as Indian mustard (Brassica juncea), a well-studied metal accumulator, exhibited severe chlorosis symptoms during some experiments. Among all the plant species studied, Chinese brake fern (Pteris vittata) accumulated significant amount of mercury in both roots and shoots and hence may be considered as a potential candidate for mercury phyto-extraction. During one experiment, Chinese brake ferns accumulated 540 mg/kg and 1469 mg/kg in shoots after 18 days of growing in soils treated with 500 parts-per-million (ppm) and 1000 ppm HgCl{sub 2} powder, respectively; no visual stress symptoms were observed. We also studied mercury phyto-remediation using aged soils that contained HgS, HgCl{sub 2}, or Hg(NO{sub 3}){sub 2}. We have found that up to hundreds of ppm mercury can be accumulated in the roots of Indian mustard plants grown with soil contaminated by mercury sulfide; HgS is assumed to be the most stable and also the predominant mercury form in flood plain soils. We have also started to investigate different mercury uptake mechanisms, such as root uptake of soil contaminant and foliar mercury accumulation from ambient air. We have observed mercury translocation from roots to shoot for Chinese fern and two Indian mustard varieties. (authors)

Su, Yi; Han, Fengxiang; Shiyab, Safwan; Chen, Jian; Monts, David L. [Institute for Clean Energy Technology (ICET), Mississippi State University, 205 Research Blvd, Starkville, MS 39759 (United States)

2007-07-01

351

The fate of arsenic in soil-plant systems.  

PubMed

Arsenic is a natural trace element found in the environment. In some cases and places, human activities have increased the soil concentration of As to levels that exceed hazard thresholds. Amongst the main contributing sources of As contamination of soil and water are the following: geologic origin, pyriticmining, agriculture, and coal burning. Arsenic speciation in soils occurs and is relatively complex. Soils contain both organic and inorganic arsenic species. Inorganic As species include arsenite and arsenate, which are the most abundant forms found in the environment. The majority of As in aerated soils exists as H?AsO?- (acid soils) or HAsO?²- (neutral species and basic). However, HA?sO? is the predomiant anaerobic soils, where arsenic availability is higher and As(III) is more weakly retained in the soil matrix than is As(V). The availability of As in soils is usually driven by multiple factors. Among these factors is the presence of Fe-oxides and/or phosphorus, (co)precipitation in salts, pH, organic matter, clay content, rainfall amount, etc. The available and most labile As fraction can potentially be taken up by plant roots, although the concentration of this fraction is usually low. Arsenic has no known biological function in plants. Once inside root cells, As(V) is quickly reduced to As(III), and, in many plant species, becomes complexed. Phosphorus nutrition influences As(V) uptake and toxicity in plants, whilst silicon has similar influences on As(III). Plants cope with As contamination in their tissues by possessing detoxification mechanisms. Such mechanisms include complexation and compartmentalization. However, once these mechanisms are saturated, symptoms of phytotoxicity appear. Phytotoxic effects commonly observed from As exposure includes growth inhibition, chlorophyll degradation, nutrient depletion and oxidative stress. Plants vary in their ability to accumulate and tolerate As (from tolerant hyperaccumulators to sensitive excluders), and some plants are useful for soil reclamation and in sustainable agriculture, The status of current scientific knowledge allows us to manage As contamination in the soil-plant system and to mitigate arsenic's effects. Phytoremediation is an emerging technology suitable for reclaiming As-contaminated soils and waters. Phytoextraction has been used to clean As-contaminated soils, although its applicability has not yet reached maturity. Phytostabilization has been employed to reduce environmental risk by confining As as an inert form in soils and has shown success in both laboratory experiments and in field trials. Phytofiltration has been used to treat As-enriched waters. Such treatment removes As when it is accumulated in plants grown in or on water. In agricultural food production, appropriate soil management and plant variety/species selection can minimize As-associated human dis- eases and the transfer of As within the food chain. Selecting suitable plants for use on As-contaminated soils may also enhance alternative land use, such as for energy or raw material production. PMID:22057929

Moreno-Jiménez, Eduardo; Esteban, Elvira; Peñalosa, Jesús M

2012-01-01

352

Environmental hazards of aluminum to plants, invertebrates, fish, and wildlife.  

PubMed

Aluminum is extremely common throughout the world and is innocuous under circumneutral or alkaline conditions. However, in acidic environments, it can be a major limiting factor to many plants and aquatic organisms. The greatest concern for toxicity in North America occurs in areas that are affected by wet and dry acid deposition, such as eastern Canada and the northeastern U.S. Acid mine drainage, logging, and water treatment plant effluents containing alum can be other major sources of Al. In solution, the metal can combine with several different agents to affect toxicity. In general, Al hydroxides and monomeric Al are the most toxic forms. Dissolved organic carbons, F, PO(3)3- and SO(4)2- ameliorate toxicity by reducing bioavailability. Elevated metal levels in water and soil can cause serious problems for some plants. Algae tend to be both acid- and Al tolerant and, although some species may disappear with reduced pH, overall algae productivity and biomass are seldom affected if pH is above 3.0. Aluminum and acid toxicity tend to be additive to some algae when pH is less than 4.5. Because the metal binds with inorganic P, it may reduce P availability and reduce productivity. Forest die-backs in North America involving red spruce, Fraser fir, balsam fir, loblolly pine, slash pine, and sugar maples have been ascribed to Al toxicity, and extensive areas of European forests have died because of the combination of high soil Al and low pH. Extensive research on crops has produced Al-resistant cultivars and considerable knowledge about mechanisms of and defenses against toxicity. Very low Al levels may benefit some plants, although the metal is not recognized as an essential nutrient. Hyperaccumulator species of plants may concentrate Al to levels that are toxic to herbivores. Toxicity in aquatic invertebrates is also acid dependent. Taxa such as Ephemeroptera, Plecoptera, and Cladocera are sensitive and may perish when Al is less than 1 mg.L-1 whereas dipterans, molluscs, and isopods seem to be tolerant. In Al-sensitive species, elevated levels (approximately 500 micrograms.L-1) affect ion regulation and respiratory efficiency. Toxicity tends to be greatest near a species' threshold of pH sensitivity. At lower pHs, Al may have a slight ameliorative effect by interfering with H+ transport across membranes. Aquatic invertebrates can accumulate very high levels of Al, but most of this appears to be through adsorption rather than assimilation. Aluminum concentrations may be as high as 5000 mg.kg-1 in insects and greater than 17,000 mg.kg-1 in other invertebrates.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7494908

Sparling, D W; Lowe, T P

1996-01-01