Hyperaccumulator Plants Research Articles

Complete genome sequence of Pseudomonas moorei strain m318 isolated from rhizosphere of Pteris multifida in high-arsenic-content soil.

Pseudomonas moorei strain m318 is an arsenite-oxidizing rhizobacterium isolated from the rhizosphere of an arsenic hyperaccumulator plant, beneficial for arsenic phytoremediation. Here, we report the complete genome sequence of this strain, which consists of a circular chromosome assembled using long reads sequenced on Nanopore and polished with Illumina paired-end reads.

Single-cell atlases reveal leaf cell-type-specific regulation of metal transporters in the hyperaccumulator Sedum alfredii under cadmium stress

Hyperaccumulation in plants is a complex and dynamic biological process. Sedum alfredii, the most studied Cd hyperaccumulator, can accumulate up to 9000 mg kg−1 Cd in its leaves without suffering toxicity. Although several studies have reported the molecular mechanisms of Cd hyperaccumulation, our understanding of the cell-type-specific transcriptional regulation induced by Cd remains limited. In this study, the first full-length transcriptome of S. alfredii was generated using the PacBio Iso-Seq technology. A total of 18,718,513 subreads (39.90 Gb) were obtained, with an average length of 2133 bp. The single-cell RNA sequencing was employed on leaves of S. alfredii grown under Cd stress. A total of 12,616 high-quality single cells were derived from the control and Cd-treatment samples of S. alfredii leaves. Based on cell heterogeneity and the expression profiles of previously reported marker genes, seven cell types with 12 transcriptionally distinct cell clusters were identified, thereby constructing the first single-cell atlas for S. alfredii leaves. Metal transporters such as CAX5, COPT5, ZIP5, YSL7, and MTP1 were up-regulated in different cell types of S. alfredii leaves under Cd stress. The distinctive gene expression patterns of metal transporters indicate special gene regulatory networks underlying Cd tolerance and hyperaccumulation in S. alfredii. Collectively, our findings are the first observation of the cellular and molecular responses of S. alfredii leaves under Cd stress and lay the cornerstone for future hyperaccumulator scRNA-seq investigations.

Comparative assessment of Brassica cultivars for genotypic variability in phytoremediation of soil exposed to lead (Pb) contamination.

The soil pollution caused with accretion of pollutant elements like lead (Pb) is the major environmental concern nowadays. Phytoremediation of contaminated soils using Brassica cultivars that act as hyperaccumulator plants for Pb emerges as an important technique for decontamination of Pb spiked soils. Therefore, pot study was carried out to compare the efficiency of three Brassica cultivars and select the most efficient cultivar for phytoremediation of Pb spiked soils. The experimental soil was contaminated with Pb applied @ 0, 125, 250, 500, 750, and 1,000 mg kg-1 soil. Our outcomes reflected that increased rates of Pb pollution in soil from 125 to 1,000 mg kg-1 soil resulted in decline of yield but enhanced the Pb acquisition of all Brassica cultivars. Comparison of cultivars indicated the highest biomass production (16.7 g pot-1), Pb acquisition (4,011.7 μg pot-1), contamination indices i.e., tolerance index (70.6), and bioaccumulation coefficient (17.03) by Brassica juncea produced thereby proving it as the most efficient cultivar for phytoremediation of Pb spiked soil.

Rhizobiome diversity of field-collected hyperaccumulating Noccaea sp.

Hyperaccumulating plants are able to (hyper)accumulate high concentrations of metal(loid)s in their above-ground tissues without any signs of toxicity. Studies on the root-associated microbiome have been previously conducted in relation to hyperaccumulators, yet much remains unknown about the interactions between hyperaccumulating hosts and their microbiomes, as well as the dynamics within these microbial communities. Here, we assess the impact of the plant host on shaping microbial communities of three naturally occurring populations of Noccaea species in Slovenia: Noccaea praecox and co-occurring N. caerulescens from the non-metalliferous site and N. praecox from the metalliferous site. We investigated the effect of metal enrichment on microbial communities and explored the interactions within microbial groups and their environment. The abundance of bacterial phyla was more homogeneous than fungal classes across all three Noccaea populations and across the three root-associated compartments (roots, rhizosphere, and bulk soil). While most fungal and bacterial Operational Taxonomic Units (OTUs) were found at both sites, the metalliferous site comprised more unique OTUs in the root and rhizosphere compartments than the non-metalliferous site. In contrast to fungi, bacteria exhibited differentially significant abundance between the metalliferous and non-metalliferous sites as well as statistically significant correlations with most of the soil parameters. Results revealed N. caerulescens had the highest number of negative correlations between the bacterial phyla, whereas the population from the metalliferous site had the fewest. This decrease was accompanied by a big perturbation in the bacterial community at the metalliferous site, indicating increased selection between the bacterial taxa and the formation of potentially less stable rhizobiomes. These findings provide fundamentals for future research on the dynamics between hyperaccumulators and their associated microbiome.

Ecological implications of chromium-contaminated effluents from Indian tanneries and their phytoremediation: a sustainable approach.

Industrial activities are paramount to sustaining the economy in a rapidly developing nation and global powerhouse like India. Leather industries are important in the country's economic map due to the high revenue and employment generation opportunities. Several of these industries contribute largely to environmental pollution. The pollution of the environment is mainly caused by improper disposal of the tannery effluents that are highly rich in hexavalent chromium, a potent human carcinogen. Hexavalent chromium imparts toxic effects on the biotic components, which include plants, animals, and humans. The review portrays the current status of the Indian leather tanning sector and its impact on the Indian economy. The process of chromium tanning and its adverse effects on the environmental biotic components have been briefly discussed. Phytoremediation of these effluents using suitable hyperaccumulating plants has been suggested as an eco-friendly and cost-effective approach for the sustainable restoration of the polluted environment. The mechanism behind the remediation approach and the factors influencing it have been detailed. The manuscript briefly discusses some important advancements in the field of phytoremediation and emerging technologies and concludes by emphasizing further research for sustainable management of tannery wastes.

Inoculation of multi-metal-resistant Bacillus sp. to a hyperaccumulator plant Sedum alfredii for facilitating phytoextraction of heavy metals from contaminated soil

Co-contamination of soil by multiple heavy metals is a significant global challenge. An effective strategy to address this issue involves using hyperaccumulators such as Sedum alfredii (S. alfredii). The efficiency of phytoremediation can be improved by supplementing with plant growth-promoting bacteria (PGPB). However, bacteria resources of PGPB resistant to multi-heavy metal contamination are still lacking. This study focused nine different strains of Bacillus and screened for resistance to heavy metals including cadmium (Cd), zinc (Zn), copper (Cu), and lead (Pb). A superior strain, Bacillus subtilis PY79 (B. subtilis), showed tolerance for all tested metals. Inoculation with B. subtilis in the rhizosphere of S. alfredii increased the accumulation of Cd, Zn, Cu, and Pb by 88.02%, 58.99%, 90.22%, and 54.97% in the plant shoots after 30 days respectively. B. subtilis application lowered the pH of the rhizosphere soil, thereby increasing the bioavailability of nutrients and heavy metals. Furthermore, B. subtilis helped S. alfredii recruit PGPB and heavy metal-resistant bacteria such as Edaphobacter, Niastella, and Chitinophaga, enhancing the growth and phytoremediation efficiency. Moreover, inoculation with B. subtilis not only upregulated genes of the ABC, HMA, ZIP, and MTP families involved in the translocation and detoxification of heavy metals but also increased the secretion of antioxidants within the cells. These findings indicate that B. subtilis enhances the tolerance, uptake, and translocation of heavy metals in S. alfredii, offering valuable insights for the phytoremediation of multi-metal-contaminated soils.

Heavy metal tolerance in crop plants: an in silico comprehensive analysis of Metal- tolerance gene family in barley

Heavy metal contamination in soil is a global concern due to its harmful effect to all living organisms. Phytoremediation is an emerging cost- effective technology, which utilizes different types of hyperaccumulator plants for the removal of heavy metal pollutants. Crop plants have been suggested as a good candidate for recultivation of agricultural soil in phytoremediation process, however the molecular mechanisms responsible for the crop tolerance to heavy metals is still unknown. Metal-tolerance proteins (MTPs) are divalent cation transporters that play critical roles in metal tolerance and ion homeostasis in plants. The current study identified 12 HvMTPs in the barley (Hordeum vulgare, Hv) genome; the majority of MTPs were hydrophobic proteins found in the vacuolar membrane. Gene expression profiling suggests that HvMTPs play an active role in maintaining barley nutrient homeostasis throughout its life cycle. The expression of barley HvMTP genes in the presence of heavy metals revealed that these MTPs were induced by at least one metal ion, implying their involvement in metal tolerance.

Lead-induced changes in plant cell ultrastructure: an overview.

Lead (Pb) is one of the most harmful toxic metals and causes severe damage to plants even at low concentrations. Pb inhibits plant development, reduces photosynthesis rates, and causes metabolic disfunctions. Plant cells display these alterations in the form of abnormal morphological modifications resulting from ultrastructural changes in the cell wall, plasma membrane, chloroplast, endoplasmic reticulum, mitochondria, and nuclei. Depending on plant tolerance capacity, the ultrastructural changes could be either a sign of toxicity that limits plant development or an adaptive strategy to cope with Pb stress. This paper gathers data on Pb-induced changes in cell ultrastructure observed in many tolerant and hyperaccumulator plants and describes the ultrastructural changes that appear to be mechanisms to alleviate Pb toxicity. The different modifications caused by Pb in cell organelles are summarized and reinforced with hypotheses that provide an overview of plant responses to Pb stress and explain the physiological and morphological changes that occur in tolerant plants. These ultrastructural modifications could help assess the potential of plants for use in phytoremediation.

Assisted Phytoremediation between Biochar and Crotalaria pumila to Phytostabilize Heavy Metals in Mine Tailings.

The increasing demand for mineral resources has generated mine tailings with heavy metals (HM) that negatively impact human and ecosystem health. Therefore, it is necessary to implement strategies that promote the immobilization or elimination of HM, like phytoremediation. However, the toxic effect of metals may affect plant establishment, growth, and fitness, reducing phytoremediation efficiency. Therefore, adding organic amendments to mine tailings, such as biochar, can favor the establishment of plants, reducing the bioavailability of HM and its subsequent incorporation into the food chain. Here, we evaluated HM bioaccumulation, biomass, morphological characters, chlorophyll content, and genotoxic damage in the herbaceous Crotalaria pumila to assess its potential for phytostabilization of HM in mine tailings. The study was carried out for 100 days on plants developed under greenhouse conditions under two treatments (tailing substrate and 75% tailing/25% coconut fiber biochar substrate); every 25 days, 12 plants were selected per treatment. C. pumila registered the following bioaccumulation patterns: Pb > Zn > Cu > Cd in root and in leaf tissues. Furthermore, the results showed that individuals that grew on mine tailing substrate bioaccumulated many times more metals (Zn: 2.1, Cu: 1.8, Cd: 5.0, Pb: 3.0) and showed higher genetic damage levels (1.5 times higher) compared to individuals grown on mine tailing substrate with biochar. In contrast, individuals grown on mine tailing substrate with biochar documented higher chlorophyll a and b content (1.1 times more, for both), as well as higher biomass (1.5 times more). Therefore, adding coconut fiber biochar to mine tailing has a positive effect on the establishment and development of C. pumila individuals with the potential to phytoextract and phytostabilize HM from polluted soils. Our results suggest that the binomial hyperaccumulator plant in combination with this particular biochar is an excellent system to phytostabilize soils contaminated with HM.

Phytoremediation in sustainable wastewater management: an eco-friendly review of current techniques and future prospects

ABSTRACT The sustainable wastewater treatment method known as phytoremediation is reviewed in this paper, with particular attention paid to important technologies including phytoextraction, rhizofiltration, phytostabilization, phytodegradation, and phytovolatilization. The study emphasizes the effectiveness of phytoextraction for heavy metal contamination using hyperaccumulator plants. It also highlights the versatility of phytoremediation by presenting compelling case examples in various situations. This environmentally friendly strategy offers affordable answers to the worldwide water pollution challenge and is in accordance with the growing demand for environmentally aware techniques. Phytoremediation – which emphasizes methods like phytoextraction – becomes a more viable path forward for wastewater pollution mitigation as environmental stewardship advances. By fusing theoretical understanding with real-world implementations, the article advances the conversation on sustainable wastewater treatment while reinforcing phytoremediation's promise for a more environmentally friendly future.

Screening potential plants in the gold mining area for phytoremediation approach

Abstract Heavy metal waste can be caused by anthropogenic activity. This waste can pollute soil and water far from the source. One of the ways to immobilize the heavy metals is using a plant that can accumulate them. This research aimed to screen potential plants that can be used as remediation agents due to ASGM activity in the post-mining area. This study was conducted at PT Napal Umbar Picung (NUP), Tanggamus Regency, Lampung. The study collected the potential hyperaccumulator plant from contaminated areas. Plant samples were dried at 80°C for three days in a ventilated oven. The dried samples were powdered using the Philips Blender 5000 series into fine-grained sizes. The powder samples were analyzed using X-ray fluorescence (XRF). The highest concentrations of As, Cd, Fe, Hg, Ni, Pb, and Zn in the shoot tissues of ASGM at PT NUP were 285.8 mg/kg, 11.7 mg/kg, 258,320 mg/kg, 501.6 mg/kg, 57.4 mg/kg, 806.2 mg/kg, and 4,520 mg/kg. The results showed that the hyperaccumulator plant of Hg was Alpinia galanga. Christella sp. Chromolaena odorata, Clidemia hirta, Melastoma malabathricum, and Nephrolepis cordifolia. This study can conclude that the plants can be used as a phytoremediation approach to heavy metals contamination such as As, Cd, Fe, Ni, Pb, Zn, and especially Hg.

Vitality behind desolation: Characteristics and succession process of plant communities in the Chongqing special steel plant brownfield

Phytoremediation is a sustainable way to clean contaminated urban soil, but selecting the right plants and designing communities is crucial. This study focuses on the vegetation in a disused steel plant in Chongqing, China, abandoned for nearly two decades. The goal is to reveal the plant community and succession patterns to inform the restoration of brownfield sites. This study combined the sample line and plot to investigate the vegetation and its growth environment in the Steel Plant. Information was recorded, including plant species, quantity, distribution, soil nutrients, humidity, and light. Cluster analysis categorized plant community types, and redundancy analysis examined the link between environmental conditions and plant types. The study found that: 1) There are 65 plant species (including 13 native trees) in the steel plant’s brownfield area, with Broussonetia papyrifera, Pteris vittata, and Debregeasia orientalis being the most abundant. The plants inside the plant were divided into seven groups based on species composition. 2) Soil moisture showed a significant positive correlation (Pearson index of 0.628) with plant survival, followed by a notable correlation with light intensity. 3) Environmental conditions partly influenced plant species composition and abundance variations. 4) 11 hyper-accumulating plant species were identified, focusing on three: the As hyper-accumulator Pteris vittata and the Cd hyper-accumulators Solanum nigrum and Debregeasia orientalis. The findings of this research will offer valuable insights for applying phytoremediation techniques in addressing contamination issues in brownfields within steel plants.

A Systematic Review on Phytoremediation of Cadmium-Contaminated Soils: Identifying Hyperaccumulator Plants, Assessing Soil Quality, Analyzing Contamination Sources and Determining Health Risks

Cadmium is a highly toxic heavy metal found in soils due to various anthropogenic and natural sources, posing significant environmental and health risks. This systematic review aimed to identify plant species that can effectively accumulate cadmium, assess soil quality and contamination sources in cadmium- affected areas, and evaluate potential health risks within affected communities. Relevant studies and articles were methodically selected from databases such as PubMed, Science Direct, Google Scholar, Research Gate, and Zendy, following Prisma Guidelines. The reviewed studies, both local and international, were published after 2000. The review found that several plant species can accumulate high levels of cadmium, with Athyrium wardii (Hook.) (Makino) achieving a 55% removal rate, Linum usitatissimum L. (Flax) achieving 32-49% removal, and T. caerulescens (Alpine Pennycress) achieving 19-36% removal. These plants showed the highest cadmium concentrations in their roots, followed by stems and leaves. Anthropogenic sources of cadmium in farm soil include agricultural activities and emissions from fuel combustion, with petrochemical industries significantly contributing through oil and gas flares, leading to elevated levels of nickel and cadmium. The review highlighted that higher cadmium accumulation poses substantial health risks, with risk concentrations higher in agricultural lands than in urban areas, implying a higher carcinogenic risk for people in these regions.

Screening and Stress Responsive Characteristics of Potential Hyperaccumulator of Pb, Zn, and Cd Compound Heavy Metals

To screen for Pb, Zn, and Cd composite heavy metal hyperaccumulator plants, a survey, sampling, and analysis of dominant plants in typical lead-zinc mines and smelter areas in Baoji City were conducted. Potential Pb, Zn, and Cd composite heavy metal hyperaccumulator plants were initially screened, and a pot experiment of soil cultivation was carried out to observe the response characteristics of chlorophyll （chlorophyll a, chlorophyll b, carotenoids, and total chlorophyll）, antioxidant enzymes （SOD, CAT, and POD）, and other physiological indicators （MDA and proline） under the stress of Pb, Zn, and Cd composite heavy metals. A field experiment was also conducted to further verify and determine their enrichment ability for Pb, Zn, and Cd composite heavy metals, aiming to provide scientific basis and technical support for the remediation of Pb, Zn, and Cd composite heavy metal-polluted soil. The field survey revealed that Symphytum officinale L. met the international hyperaccumulator plant index requirements for the enrichment of Pb, Zn, and Cd, with enrichment quantity, bioconcentration factor （BCF）, and transfer factor （TF） all meeting the requirements. It was a potential hyperaccumulator plant for Pb, Zn, and Cd composite heavy metals. The soil cultivation pot experiment showed that as the gradient of Pb, Zn, and Cd composite heavy metal stress increased, the content of chlorophyll a, chlorophyll b, and total chlorophyll in S. officinale L. leaves gradually decreased, causing disruption to the plant's photosynthetic system when the gradient was greater than or equal to IV. The chlorophyll content in Ricinus communis L. leaves exhibited a "low-stimulation-high-inhibition" phenomenon, while excessive stress stimulated the activation of its own protective systems, leading to reduced toxicity. In addition, there were significant differences （P < 0.05） in the content of chlorophyll a, chlorophyll b, carotenoids, and total chlorophyll between S. officinale L. and R. communis L. both compared to the control treatment and between stress gradients. The SOD activity in the leaves of S. officinale L. and R. communis L. showed a trend of increasing first, then decreasing, and then increasing. The CAT activity in the leaves of S. officinale L. exhibited a "low-stimulation-high-inhibition" effect, whereas the CAT activity in the leaves of R. communis L. showed a trend of continuous decrease. The POD activity in the leaves of S. officinale L. generally increased, whereas in the leaves of R. communis L., it increased first, then decreased, and then increased. The MDA content in the leaves of S. officinale L. generally decreased, whereas in the leaves of R. communis L., it exhibited an upward trend. In addition, whether compared to the control between stress gradients, there were significant differences （P < 0.05） in the SOD, CAT, POD, MDA, and proline content of S. officinale L. and R. communis L. The field experiment results indicated that S. officinale L. could meet the hyperaccumulator plant index requirements for the enrichment of Pb, Zn, and Cd, making it a potential germplasm resource for Pb, Zn, and Cd composite heavy metal hyperaccumulator plants. It can be an ideal choice for the remediation of Pb, Zn, and Cd composite heavy metal-polluted soil.

The dynamic response mechanism of crops to manganese uptake and transfer mediated by different intercropping crop attributes.

An issue of pressing concern is the manganese contamination in farmland soils adjacent to industrial areas. To address this, intercropping hyperaccumulator plants with crops emerges as a sustainable approach to ensuring food security. This study aims to investigate the influence of intercropping Sedum alfredii with maize or soybean on their growth and the dynamics of manganese accumulation through field experiments. The results showed that compared with monoculture, the Sedum alfredii-maize intercropping system exhibited a land equivalent ratio (LER) of 1.89, signifying a 71.13% augmentation in bioaccumulation amount (BCA). Additionally, it led to a significant reduction in manganese content in various organs, ranging from 17.05% to 25.50%. However, the Sedum alfredii-soybean intercropping system demonstrated a LER of 1.94, accompanied by a 66.11% increase in BCA, but did not significantly reduce the manganese content in the roots, stems, and pods of soybeans. Furthermore, manganese accumulation in maize and soybean grains was primarily attributed to the aboveground translocation of manganese. The intercropping effect on blocking manganese absorption of maize during growth and maturity is primarily attributed to the earlier manganese accumulation in intercropped maize by 2.63 to 4.35 days, and a reduction of 21.95% in the maximum manganese accumulation rate. The study found that manganese accumulation dynamics vary significantly depending on the crop family. Intercropping Sedum alfredii with maize enhances land-use efficiency and reduces manganese uptake by crops, making it a promising strategy for remediating manganese-contaminated farmland near industrial areas. © 2024 Society of Chemical Industry.

Potential Combination of Phytoremediation Plants and Compost in Remediation of Hg in Ex-Gold Mine Soil Contaminated Mercury (Hg)

Heavy metal mercury pollution in the environment can have negative impacts on both surrounding ecosystems and human health. Sources of mercury pollution often come from mining activities, particularly from many unlicensed gold mines (PETI) that use the mercury amalgamation method to extract gold. Due to the persistent, bioaccumulative, and toxic nature of mercury, contamination in the soil has increased. One effort to reduce mercury toxicity is the application of absorption methods using phytoremediation plants and compost as regulating factors. The aim of this study is to review sources of information related to the use of phytoremediation plants and the application of compost as remediators to clean mercury (Hg)-contaminated soil. To reduce levels of heavy metal contamination, plants employ five phytoremediation mechanisms: phytoextraction, phytostabilization, rhizofiltration, phyto degradation, and phytovolatilization. Therefore, selecting hyperaccumulator plants that have the ability to accumulate mercury (Hg) at levels 100 times higher than ordinary plants is crucial for effective remediation. Additionally, the use of compost as a source of organic material can enhance mercury mobility. The addition of organic materials such as compost can increase C organic content, cation exchange capacity (CEC), pH, and Hg-chelate formation, thereby maximizing mercury absorption by plants. This combination has a positive impact on reducing mercury levels in the soil and is environmentally safe.

Transcriptome and protein-protein interaction analysis reveals the tolerance of poplar to high boron toxicity regulated by transport and cell wall synthesis pathways

Soil contamination with high levels of boron (B) destroys the balance of the soil ecosystem, reduces crop yields and poses a potential threat to human health and safety. Hyperaccumulator plants such as poplar can be used to mitigate high B soil contamination and its negative effects. Despite having a certain level of understanding of the physiological response of poplars to high boron stress tolerance, the differences in boron accumulation efficiency among different clones and their underlying molecular mechanisms are still unclear. The effects of high B toxicity on growth, B accumulation and physiological parameters were investigated in this research to compare the high B tolerance and high B accumulation abilities of five poplar clones (717, SXY, NL895, 84 K, and T89). Then two poplar clones (SXY and T89) were selected, due to their differences in B content and accumulation under high B toxicity, for transcriptomic and protein-protein interactions (PPI) analysis. The plant biomass and root-to-shoot ratio were reduced, the leaves exhibited symptoms of chlorosis and shrinkage of high B stressed five poplar clones. Boron toxicity significantly decreased the net photosynthetic rates, disturbed the balance of redox, induced the accumulation of H2O2 and malondialdehyde (MDA), and caused the increase in free proline levels in roots and leaves. B accumulation was significantly increased in the high B treated new leaves. The SXY clones showed the highest B accumulation, making it a potential hyperaccumulator for B contaminated soils. The transcriptome analysis of SXY and T89 revealed differential expression of genes involved in cell wall organization, active transmembrane transporter activity, cell wall synthesis, and B transport. The analysis of PPI indicates that these proteins work together in group functions. We identified some key differentially expressed genes (DEGs) related to transport and cell wall degradation. Our findings suggest that poplar is a plant that can tolerate high levels of boron, and it is possible to select poplar clones that accumulate high levels of boron to reduce soil boron pollution. The potential candidate genes, involved in transport and cell wall synthesis, can be focused on to improve poplar tolerance to high B in future breeding programs.

Bacteria from the rhizosphere of a selenium hyperaccumulator plant can improve the selenium uptake of a non-hyperaccumulator plant

Bacteria from the rhizosphere of a selenium hyperaccumulator plant can improve the selenium uptake of a non-hyperaccumulator plant

Heavy metals removal from industrial wastewater of Biskra (Algeria) by Arundo donax and Phragmites australis.

Industrial effluents pose a serious environmental problem, because they contain toxic contaminants mainly heavy metals that are the most dangerous to humans, animals, plants, and the environment in general. Phytoremediation using macrophytes is an adopted technique for the environment decontamination due to its efficiency and cost-effectiveness. The present study aims to highlight the capabilities of macrophytes to remove heavy metals from wastewater of Biskra region (Algeria). The methodology consists of filling out the filters planted with Arundo donax and Phragmites australis with raw industrial wastewater, then recovering decontaminated water after 15 days to assess removal of lead, copper, zinc, and iron. Both plants had shown a good efficiency for the removal of metals loaded in wastewater eliminating about 94 to 98% of initial concentration. In addition, calculated bioaccumulation factor (BAF) had confirmed the accumulation of heavy metals in different parts of experimental plants; recorded values of BAF > 1 allowed the consideration of Arundo donax and Phragmites australis as good hyper-accumulator plants. Obtained results confirm the efficiency of phytoremediation technology using macrophytes for the wastewater treatment in particular and the environment decontamination in general.

In vivo imaging of nickel-rich laticifers: A breakthrough in metal hyperaccumulation

The discovery of the nickel-rich latex of the New Caledonian endemic tree Pycnandra acuminata introduced the term ‘hyperaccumulator’ and gave rise to a new field of research. This then instigated a global quest for these unusual hyperaccumulator plants, even while the underlying mechanisms of nickel acquisition, transport, and internal elemental distribution remained unknown for this original laticifer-bearing hyperaccumulator plant. Here we reveal for the first time the distribution of nickel-filled laticifers in the different plant organs of P. acuminata. The pressurised nickel laticifers were imaged multimodally with a combination of synchrotron X-ray fluorescence (XRF) microscopy, microtomography (XRF-μCT) and synchrotron X-ray phase contrast imaging microtomography (PCI-μCT). These advanced synchrotron methodologies allowed for complimentary non-invasive reconstructions of an in-situ model of the laticiferous system in this species. The data shows the distribution of the nickel-rich laticifers within whole plant tissues from roots to apical tip, thus suggesting nickel trafficking in the laticifer network. The extraordinary concentration of nickel within P. acuminata laticifers functions as an effective natural tracer for XRF-μCT and PCI-μCT to probe the structure and organization of these cells, thereby permitting insights into the development and physiological functioning of this unique duct system.