Metal Accumulation Potential Research Articles

Phytoassessment of Vetiver grass enhanced with EDTA soil amendment grown in single and mixed heavy metal-contaminted soil.

Over the years, ethylene-diamine-tetra-acetate (EDTA) has been widely used for many purposes. However, there are inadequate phytoassessment studies conducted using EDTA in Vetiver grass. Hence, this study evaluates the phytoassessment (growth performance, accumulation trends, and proficiency of metal uptake) of Vetiver grass, Vetiveria zizanioides (Linn.) Nash in both single and mixed heavy metal (Cd, Pb, Cu, and Zn)-disodium EDTA-enhanced contaminated soil. The plant growth, metal accumulation, and overall efficiency of metal uptake by different plant parts (lower root, upper root, lower tiller, and upper tiller) were thoroughly examined. The relative growth performance, metal tolerance, and phytoassessment of heavy metal in roots and tillers of Vetiver grass were examined. Metals in plants were measured using the flame atomic absorption spectrometry (F-AAS) after acid digestion. The root-tiller (R/T) ratio, biological concentration factor (BCF), biological accumulation coefficient (BAC), tolerance index (TI), translocation factor (TF), and metal uptake efficacy were used to estimate the potential of metal accumulation and translocation in Vetiver grass. All accumulation of heavy metals were significantly higher (p < 0.05) in both lower and upper roots and tillers of Vetiver grass for Cd + Pb + Cu + Zn + EDTA treatments as compared with the control. The single Zn + EDTA treatment accumulated the highest overall total amount of Zn (8068 ± 407 mg/kg) while the highest accumulation for Cu (1977 ± 293 mg/kg) and Pb (1096 ± 75 mg/kg) were recorded in the mixed Cd + Pb + Cu + Zn + EDTA treatment, respectively. Generally, the overall heavy metal accumulation trends of Vetiver grass were in the order of Zn >>> Cu > Pb >> Cd for all treatments. Furthermore, both upper roots and tillers of Vetiver grass recorded high tendency of accumulation for appreciably greater amounts of all heavy metals, regardless of single and/or mixed metal treatments. Thus, Vetiver grass can be recommended as a potential phytoextractor for all types of heavy metals, whereby its tillers will act as the sink for heavy metal accumulation in the presence of EDTA for all treatments.

Tools for non-invasive sampling of metal accumulation and its effects in Mediterranean pond turtle populations inhabiting mining areas

Among reptiles, freshwater turtle species have high potential for metal accumulation because of their long lifespan or their aquatic and terrestrial habits. In order to monitor metal bioaccumulation, determine potential toxic effects, and investigate tools for non-invasive metal sampling in reptiles, we studied lead (Pb) and mercury (Hg) accumulation in Mediterranean pond turtles (Mauremys leprosa) inhabiting two former mining areas, one of them with high environmental concentrations of Pb (Sierra Madrona-Alcudia Valley district) and the other one with high environmental concentrations of Hg (Almadén district). Individuals from the Pb mining area showed mean blood concentrations (i.e. 5.59 μg Pb/g dry weight, d.w.) that were higher than those measured in other populations. Blood Hg concentrations were highest (8.83 μg Hg/g d.w.) in the site close to the former Hg mines, whereas blood Hg concentrations in terrapins from another site of Almadén district, located ∼28 km downstream, were not different from locations at the non-mining area. Animals from the Pb-contaminated site showed evidence of oxidative stress, whereas those from the Hg-contaminated site showed increased activity of the antioxidant enzyme glutathione peroxidase, as well as reduced circulating levels of the main endogenous antioxidant peptide, glutathione. Concentrations measured in feces and carapace scutes were useful indicators to monitor blood concentrations of Pb, but not of Hg. Our results provide evidence of the usefulness of freshwater turtles as sentinels of chronic metal pollution, and validate non-invasive tools to advance Pb monitoring in reptiles.

Phytoremediation of Lead and Chromium Contaminated Soil Improves with the Endogenous Phenolics and Proline Production in Parthenium, Cannabis, Euphorbia, and Rumex Species

Phytoremediation is the most promising and emerging technology for remediation of metal-contaminated sites. The aim of the current research was to investigate the metals accumulation potential of four weed species i.e., Parthenium, Cannabis, Euphorbia, and Rumex species. The endogenous free proline, total phenolic, carotenoids, and chlorophyll contents were assessed under metals stress and correlated with metals accumulation in plants. Plants of each species were allowed to grow in reference (uncontaminated) soil and other group on industrial effluent-contaminated soil under natural environment. Phytoextraction potentials of these plants were evaluated for removal of lead (Pb) and chromium (Cr). The heavy metal concentration in plant parts was analyzed by atomic absorption spectrophotometer. Varied accumulation of metals was found among different weed species. Moreover, metal accumulation was different within plant tissues i.e., roots, leaves, and stem. Cannabis and Parthenium showed bio-concentration BCF > 1 for Pb, reflecting their high metal accumulation potential and both plants were found superior than Rumex and Euphorbia for Cr accumulation. The endogenous free proline and phenolic contents showed significantly positive correlation with Pb accumulation in four plants i.e., Parthenium (R2 = 0.977, R2 = 0.9996), Cannabis (R2 = 0.9924, R2 = 0.9999), Euporbia (R2 = 0.9992, R2 = 0.9832), Rumex (R2 = 0.6033, R2 = 0.8272) respectively. Similarly, Cr accumulation in plants showed significantly positive correlation with proline and phenolic but the BCF ˂ 1.The chlorophyll and carotenoids contents in all plants negatively correlated with Pb and Cr concentration.

Investigating metal removal potential of aquatic macrophytes at different harvest regimes to maximize remediation of metal contaminated wastewater in constructed wetland

In present study, the metal accumulation potential and growth dynamics of two aquatic macrophytes viz. Sagittaria sagittifolia and Colocasia esculenta were investigated at varying harvest time and frequency for maximum metal removal from mixed industrial wastewater employing horizontal flow constructed wetland (CW) technology. Both plant species were harvested five times i.e. 0, 30, 60, 90 and 120 days during experiment. S. sagittifolia attained maximum biomass (216.2 g dw m−1) and growth rate (1.25 g plant−1 day−1) at H3, whilst that of C. esculenta (204.3 g dw m−1 and 1.01 g plant−1 day−1 respectively) at H4. The plant species also differed in their metal uptake capability. With exception of Cr, other heavy metals viz. Zn, Cu and Cd accumulated more in S. sagittifolia than C. esculenta. In general, the metal uptake efficiency of S. sagittifolia was higher than that of C. esculenta, which increased up to H3 in former, whilst up to H4 in latter. The maximum Zn, Cu and Cd removal (115.55, 53.78 and 4.26 g/wetland respectively) was observed by S. sagittifolia in CW1, whilst Cr removal (12.79 g/wetland) by C.esculenta was recorded in CW2. Both plants showed metal tolerance ability in terms of reduced and oxidized glutathione content in their leaves. As such, the optimum harvesting regimes (time and frequency) in sequential manner accumulating maximum metals could enhance the metal removal efficiency of aquatic macrophytes.

THE POTENTIAL IMPACT OF LANDFILL ON THE NEAR VICINITY WITH THE USE OF HEAVY-METAL ACCUMULATOR PLANTS

This study was conducted to screen plants growing on potentially contaminated areas of landfill body and nearest surrounding to determine their potential for metal accumulation. In addition, enrichment coefficient (EC) for plant/soil system, correlation and principal component analysis were used for determining the environmental contamination from landfill in terms of heavy metal (HM) accumulation. The examined plant samples meet the stated requirements. The highest values in samples 1 -8 reached Fe (491 191 000 mg/kg DM), the second values were Mn (35.1 342 mg/kg DM) and the third was Zn (26.9 145 mg/kg DM). The highest concentrations of Co, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were observed (in order) in plant samples 4, 2 and 1, i.e. plants collected in the vicinity of the landfill. The examined soil samples meet the stated requirements. The highest values in samples 1 -8 reached Fe (23 300 to 63 400 mg/kg DM), the second were recorded for Mn (527-908 mg/kg DM) and the third was Zn (83.0 -519 mg/kg DM). The highest concentrations of Co, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were observed (in order) in soil samples 7, 2 and 5. EC was calculated for all 8 sampling points. The highest degree of accumulation was observed for Cd in all 8 sampling points. In contrast, the lowest concentration of all the examined heavy metals was determined for Cd in plant and soil samples.

Screening &amp; Assessment of Heavy Metal Accumulation Potential of Amaranthus Spinosus &amp; Cassia Tora In &amp; Around the Vicinity of Anand, Gujarat

Screening &amp; Assessment of Heavy Metal Accumulation Potential of Amaranthus Spinosus &amp; Cassia Tora In &amp; Around the Vicinity of Anand, Gujarat

Environmental assessment of the effects of a municipal landfill on the content and distribution of heavy metals in Tanacetum vulgare L.

Heavy metal pollution is an important concern because of its potential to affect human health. This study was conducted to analyze plants growing on a landfill body and in its surroundings to determine their potential for heavy metal accumulation. In addition, the enrichment coefficient (EC) for the plant/soil system was used for determining the environmental contamination from a landfill in terms of heavy metal accumulation. The samples were taken in 2013–2014. Of the analyzed metals, iron achieved the highest values in the samples, i.e. - stalk (103.4–6564.6 mg/kg DM), roots (6563.6–33,036.6 mg/kg DM), leaf (535.1–11,275 mg/kg DM) and soil (12,389–39,381.9 mg/kg DM). The highest concentrations were determined in 2013 for Fe, Mn and Zn. Iron achieved the highest concentrations in the years 2013–2014. Next, EC values were then calculated, with the highest noted for Cd. Cd, as well as Cr, Ni and Zn are accumulated mostly in the leaves, whereas Co, Cu, Fe, Hg, Mn and Pb are accumulated mainly in the roots of T. vulgare.

Accumulation of heavy metals in native plants growing on mining-influenced sites in Jinchang: a typical industrial city (China)

Such activities as mining, metal ore smelting and the discharging of mining wastes lead to heavy metal contamination. Phytoremediation, including phytoextraction and phytostabilization, has been considered for a long time to be effective in remediating metal-polluted soils. This research assessed the chance of 40 plants (35 species) distributing on mining-influenced sites for phytoremediation purposes. The results showed that total soil Ni, Cu, Cd, Cr and Co concentrations were in the ranges of 107–3045, 116–2580, 7.1–22.7, 115–897 and 23.2–144.3 mg kg−1, respectively, whereas heavy metal contents in plants were in the ranges of 0.60–435.61, 2.41–298.31, 0.03–32.10, 0.08–88.20 and 0.11–28.52 mg kg−1, respectively. Therefore, no species can be used for phytoextraction purposes because no hyperaccumulator was identified. Salsola passerine, Stipa capillata, Cynanchum Chinense and Halogeton glomeratus with translocation factor (TF) > 1 for all five metals were considered to be accumulators. All plants were observed to hold a bioconcentration factor (BCF) 1, reflecting its low metal accumulation potential. Among the species studied, Oxytropis aciphylla, Salix matsudana, Tamarix hispida, Robinia pseudoacacia, Picea crassifolia, Lycium barbarum and Phragmites communis had both a BCF and TF < 1 for all five metals and were considered the most suitable for the phytostabilization of metal-polluted sites.

Heavy Metal tolerant Non endosymbiont PGPR’s; Psuedomonas spp. and Bacillus spp. associated with the roots of evergreen shrubs Casuarinas equisetifolia

There is a lack in research related to association of non-endosymbiont bacteria with Casuarina sp. PGPR non-endosymbiont bacteria like pseudomonas sp. and Bacillus sp. are long associated with their properties of heavy metal accumulation and plant growth promoting activity. The present study focuses on heavy metal tolerant and accumulation potential of non endosymbiont PGPR isolated from rhizosphere of Casuarina equisetifolia . The plant growth promoting properties was studied by pot culture studies on fast growing Indian moth bean Vigna aconitifolia . In the pot culture study three bacterial isolates were found to be increasing the root and shoot length by Pseudomonas sp. RS-1 (7.4±0.64 and 21.7±1.42), Bacillus sp. RS-2 (6.5±0.93 21.2±2.09) and and Bacillus sp. RS-3 (6.4±0.73 19.1±1.83) respectively. The maximum tolerance concentration of Pseudomonas sp. RS-1 shows 200 mg/L towards Cr (VI), Pb (II) 150 mg/L whereas tolerance for Cd (II), and Zn (II) were 100mg/L. Maximum % removal was shown by Bacillus sp. RS-3 towards Cr, Pb and Zn (42.51, 26.35 and 26.65 % respectively), Pseudomonas sp. RS-1 towards Cd (36.52 %). As Frankia ecological interaction between non-endosymbiont bacteria and phytoremediation ability of Casuarina sp. is not fully understood. Further study in this area may lead to better prospect in application of Casuarina as a phytoremediation agent.

Exploring metal detoxification and accumulation potential during vermicomposting of Tea factory coal ash: sequential extraction and fluorescence probe analysis.

Metal contamination from coal ashes (CAs) is widely recognized as a significant environmental concern. To learn more about metal detoxification and accumulation potential of earthworm species, metal-rich tea factory coal ashes (TFCA) were fed to Eisenia fetida and Lampito mauritii by employing a fluorescent tag detection method. Fascinatingly, on feeding fluorescence probed Zn and Cd along with cow dung to Eisenia fetida, the detection of the gut-proteins with a molecular mass higher than 100 kDa was a distinct evidence of metal binding. Significant increases were observed in the content of humified organic C [humic acid (HAC) and fulvic acid C (FAC)] and degree of humification during vermicomposting. Concurrently, considerably large amount of toxic metals (Cr, Cd, Pb, and Zn) was transformed from exchangeable to recalcitrant (organic matter and mineral bound) fractions. Moreover, total metal concentrations were reduced with high removal efficiency upon vermicomposting.

Anti-oxidative feedback and biomarkers in the intertidal seagrass Zostera japonica induced by exposure to copper, lead and cadmium

To investigate the potential influences of anthropogenic pollutants, we evaluated the responses of the intertidal seagrass Zostera japonica to three heavy metals: copper (Cu), lead (Pb), and cadmium (Cd). Z. japonica was exposed to various concentrations of Cu, Pb, and Cd (0, 0.5, 5, 50μM) over seven days. The effects were then analyzed using the antioxidant enzyme catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), glutathione peroxidase (GPX), and lipid peroxidation measured using malondialdehyde (MDA) as proxy. Metal accumulation in the above-ground tissues and phenotypic changes were also investigated. Our results revealed that heavy metal concentration increased in seagrass exposed to high levels of metals. Z. japonica has great potential for metal accumulation and a suitable candidate for the decontamination of moderately Cu contaminated bodies of water and can also potentially enhanced efforts of environmental decontamination, either through phytoextraction abilities or by functioning as an indicator for monitoring programs that use SOD, CAT, GPX, POD and MDA as biomarkers.

Seasonal profile of metal accumulation in the acanthocephalan Pomphorhynchus laevis: a valuable tool to study infection dynamics and implications for metal monitoring

BackgroundA large number of studies demonstrated that acanthocephalans exhibit a high metal accumulation potential and thus can be used as sensitive accumulation indicators. However, similar to free-living bioindicators, a seasonal variation in metal concentrations in parasites might occur. Accordingly, the influence of seasonality has to be elucidated if parasites should be applied as sentinels.MethodsIn order to assess a possible seasonal profile of element concentrations, the concentrations of As, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, V and Zn in the acanthocephalan Pomphorhynchus laevis and in its host barbel (Barbus barbus) were analysed in a seasonal manner (spring, summer and autumn) using inductively coupled plasma mass spectrometry (ICP-MS).ResultsFive elements (As, Cd, Cu, Pb and Zn) were detected in significantly higher concentrations in the parasites compared to host muscle, intestine and liver. Their levels in P. laevis showed a clear seasonal pattern, while the concentrations in the fish tissues remained similar during the year. The highest concentrations in the parasites were found in autumn, followed by spring and summer. Evidence from the literature suggests that this profile coincides with the seasonality of acanthocephalan transmission, as their annual concentration profile reflected the mean individual weight pattern during the year. Parasite infrapopulations in autumn consisted mainly of young worms which are characterised by an accelerated metabolism and a higher surface to volume ratio resulting in higher element concentrations when compared to older worms which are assumed to slow down their metabolism and additionally excrete metals with their eggs.ConclusionsBased on the available data from the present study and literature, a model is suggested, which visualises the accumulation kinetic of several elements under natural conditions. According to the element accumulation data the lifespan of P. laevis in barbel was roughly estimated to range between six and eight months.

Elucidation of zinc and copper induced oxidative stress, DNA damage and activation of defence system during seed germination in Cassia angustifolia Vahl

Investigations conducted on Cassia angustifolia to see the effect of zinc (Zn) and copper (Cu) during seed germination, revealed drastic toxicity on seedling growth, alteration in antioxidant enzymes, morphological changes and metal accumulation in various plant parts. Seeds were germinated on Knop’s medium containing Zn and Cu individually in various concentrations (0, 1, 10, 50, 100 and 200mgL−1). Decline in seed germination initiated above 1mgL−1 and maximum inhibition was seen at 200mgL−1 where it was 40 and 25.0%, respectively under Zn and Cu over control (67.67%). Average shoot length decreased from 5.53cm (control) to 2.1 and 1.4cm whereas average root length decreased from 7.12cm (control) to 1.5 and 0.3cm under Zn and Cu, respectively. Atomic absorption spectroscopy revealed that maximum Zn and Cu (1682.48 and 9516.99mgkg−1 dry weight, respectively) were stored in roots. Superoxide dismutase activity increased up to 2.71 and 3.27 fold at 200mgL−1 Zn and Cu, respectively. Catalase, ascorbate peroxidase, guaiacol peroxidase and glutathione reductase followed similar trend. Malondialdehyde and proline content accounted for 52.7μmolmg−1 and 10.0μmolg−1 fresh weight, respectively in control seedlings. Malondialdehyde increased up to 2.5 and 3.33 fold and proline up to 9.42 and 11.20 fold at 200mgL−1 Zn and Cu, respectively. Comet assay revealed extensive DNA damage at higher concentration and protein analysis showed various low molecular weight proteins (20–14kDa) at higher concentration. This is our first report of in vitro heavy metal stress study on C. angustifolia. Induction of anti-oxidative response and proline accumulation suggests the tolerance strategy adopted by C. angustifolia and its high metal accumulation potential can be utilized in phytoremediation.

Heavy Metal Accumulation Potential of Some Wetland Plants Growing Naturally in the City of Kolkata, India

Freshwaters are not only used locally in many developing countries but they are often over exploited for domestic purposes, agriculture and disposal of industrial wastes which result in an overload of excess nutrients, harmful chemicals and heavy metals. Plant species together with sediments and water samples collected from eleven aquatic water bodies in the vicinity of industrial units in Kolkata were studied for their potential to uptake Pb, Cd and Cr under field conditions. Cd and Cr concentrations in the sediments were higher than background values considered to be toxic. Alternanthera philoxeroides and Eichhornia crassipes were the two invasive species present, with the former being more widely distributed. Among native plants, Ipomoea aquatica was the most abundant. Metal uptake in the plants differed among species, tissues and sites. Pb and Cd accumulation in root tissues for all plants in most sites suggested an exclusion strategy for metal tolerance. Since I. aquatica is widely consumed in many parts of SE Asia, its metal content should be checked before use since it was found to efficiently translocate both Pb and Cd from roots to shoots. The potential of A. philoxeroides as a metal excluder needs to be explored further since it translocates less to its shoots as compared to E. crassipes and I. aquatica.

An Assessment of Metal in Fly Ash and Their Translocation and Bioaccumulation in Perennial Grasses Growing at the Reclaimed Opencast Mines

Rapid expansion of the industrial sector adds more effluent into the agricultural land and in the vicinity of industry, which possesses the major threat of land contamination and environmental degradation. The present study was conducted to determine toxic metal concentration in fly ash and metal accumulation potential of the Saccharum munja and Cynodon dactylon, the two main grass species growing naturally on fly ash lagoon for Fe, Ni, Zn, Cu, Mn, Pb and Cd. Accumulation of metals were found in the order of Fe > Zn > Mn > Cu > Ni > Pb and Cd. In spite of significant accumulation of Fe in the root and shoot, the BCF and BAC were found very low ( 1 for Zn and Pb) and low bioaccumulation coefficient (<1 for Fe, Mn, Ni, Cu and Cd) suggests its suitability for phytoremediation of fly ash lagoons. Findings of the study suggest that weed species may be used for the stabilization of toxic metals contaminated land and to empower the rural economy.

Preparation of vectors with metallothionein gene enriched by additional metal binding domain and their transient expression in Nicotiana tabacum

The issue of finding plants suitable for phytoremediation of inorganic contaminants can be addressed through the preparation of genetically modified plants with an increased metal accumulation potential. A HisCUP gene, which encodes for a yeast metallothionein fused with a polyhistidine tail (His), was chosen for preparation of two plant vectors. These two plant vectors were constructed and a HisCUP gene expression was subsequently investigated. We firstly prepared a vector pNOV2819/RbcS/HisCUP which enabled selection on a mannose medium and contained the HisCUP gene under an inducible Rubisco promoter. Secondly, we designed a vector pGreen0029/35S/HisCUP which enabled selection of plants on a medium with kanamycin and carried the HisCUP gene under a constitutive CaMV 35S promoter. The transient expression of the HisCUP gene in tobacco plants was confirmed at RNA and protein levels for both constructs. The relative expression of the HisCUP gene was determined by semi-quantitative real-time PCR; a higher expression was detected for the vector pNOV2819/RbcS/HisCUP.

Interaction of Heavy Metals in Multimetal Biosorption by Galerina vittiformis from Soil

ABSTRACT Soil heavy metal contamination, a major threat due to industrialization, can be tackled by an efficient and economical process called bioremediation. Mushrooms are employed to accumulate heavy metals from soil due to their high metal accumulation potential and better adaptability. The bioaccumulation potential of Galerina vittiformis was already reported for individual metals. At natural conditions, since soil consists of more than one polluting metal, more focus has to be given to multimetal systems. In this study, multimetal accumulation potential was analyzed using central composite design, and the responses obtained were analyzed using response surface methodology. Heavy metals such as Cu(II), Cd(II), Cr(VI), Pb(II), and Zn(II) were subjected to biosorption at 10–250 mg/kg concentrations along with pH 5–8. The results showed that the preference of the organism for the five metals under study was in the order Pb(II) > Zn(II) > Cd(II) > Cu(II) > Cr(VI) at pH 6.5 under multimetal condition. The study also indicates that the metal interaction pattern in multimetal interaction is a property of their ionic radii. The response surface methodology clearly explains the effect of interaction of heavy metals on the accumulation potential of the organism using three-dimensional response plots. The present work suggests that the fungus Galerina vittiformis could be employed as a low-cost metal removal agent from heavy metal–polluted soil.

Phytoextraction capacity of Pelargonium graveolens L’Hér. grown on soil amended with tannery sludge – Its effect on the antioxidant activity and oil yield

The metal accumulation potential of Pelargonium graveolens L’Hér. grown with various amendments of heavy metal (HM) rich tannery sludge (TS) was studied. Root accumulated more metals followed by leaves and stem. At 50:50 ratio of TS and soil, translocation factor (TF) for Cd, Co, Ni, Pb and Cr were 0.77, 0.74, 1.09, 0.81 and 0.70, respectively. Chlorophyll a, chlorophyll b, carotenoid content and biomass of plant were high at 50:50 ratio of sludge and soil. Maximum oil content was observed at the same ratio of sludge and soil. No detectable amount of metal was found in the oil of P. graveolens. Citronellol, geraniol (C/G) ratio was close to 1 at 50:50 ratio of TS and soil, which is considered to be the best oil quality and most preferred by the industries. HMs present in TS increased oxidative stress in plant resulting in increased level of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), proline and melondialdehyde (MDA) at all ratios of TS and soil as compared to control. At 100% TS without soil antioxidant activity decreased which indicated that high concentration of HMs impaired the oxygen scavenging function. Translocation factor emphasized that 50:50 ratio of TS and soil were suitable for extraction of various metals without affecting the oil yield of P. graveolens. So, this plant can be suggested as a good candidate to be grown in metal polluted soil vis-à-vis for phytostabilization of metals.

Rhizoremediation potential of spontaneously grown Typha latifolia on fly ash basins: Study from the field

Lesson of the phytoremediation from the field research is a current need. In this regard, we took a field study on the phytoremediation of fly ash (FA) basins. Increasing disposal area of FA is an environmental concern and poses a threat to various ecosystems worldwide. Luxuriant and spontaneous growth of Typha latifolia on FA basin revealed its toxitolerant characteristics and colonizer nature. The metal accumulation of Zn, Mn, Cu, Pb, Cd, Cr and Ni ranged from 72 to 133, 80 to 183, 8 to 43, 3 to 16, 2 to 8, 4 to 37 and 10 to 36μgg−1in root, rhizome and middle part of leaf in T. latifolia plant grown under flooded and non-flooded conditions of FA basin, respectively. The bioconcentration factor (BCF) calculated under both flooded and non-flooded conditions for Zn, Mn and Ni in all plant parts were found to be greater than one. The BCF value for Cr was greater than one in root and rhizome parts of the plant, whereas BCF value for Pb was higher than one only in root part. This clearly shows the metal accumulation potential of T. latifolia. The translocation factors (TF) for all the metals were lower than one except for Mn metal under both the conditions. These field results revealed that T. latifolia is a suitable candidate for the rhizoremediation of heavy metals in FA basin because of its lower TF values than one. Being cosmopolitan and perennial nature it may be used for the rhizoremediation of FA basins worldwide.

Heterologous expression of Ceratophyllum demersum phytochelatin synthase, CdPCS1, in rice leads to lower arsenic accumulation in grain.

Recent studies have identified rice (Oryza sativa) as a major dietary source of inorganic arsenic (As) and poses a significant human health risk. The predominant model for plant detoxification of heavy metals is complexation of heavy metals with phytochelatins (PCs), synthesized non-translationally by PC synthase (PCS) and compartmentalized in vacuoles. In this study, in order to restrict As in the rice roots as a detoxification mechanism, a transgenic approach has been followed through expression of phytochelatin synthase, CdPCS1, from Ceratophyllum demersum, an aquatic As-accumulator plant. CdPCS1 expressing rice transgenic lines showed marked increase in PCS activity and enhanced synthesis of PCs in comparison to non-transgenic plant. Transgenic lines showed enhanced accumulation of As in root and shoot. This enhanced metal accumulation potential of transgenic lines was positively correlated to the content of PCs, which also increased several-fold higher in transgenic lines. However, all the transgenic lines accumulated significantly lower As in grain and husk in comparison to non-transgenic plant. The higher level of PCs in transgenic plants relative to non-transgenic presumably allowed sequestering and detoxification of higher amounts of As in roots and shoots, thereby restricting its accumulation in grain.