Hyperaccumulator Plants Research Articles

Quantitative proteome analysis reveals changes of membrane transport proteins in Sedum plumbizincicola under cadmium stress

Sedum plumbizincicola is an herbaceous species tolerant of excessive cadmium accumulation in above-ground tissues. The implications of membrane proteins, especially integrative membrane proteins, in Cd detoxification of plants have received attention in recent years, but a comprehensive profiling of Cd-responsive membrane proteins from Cd hyperaccumulator plants is lacking. In this study, the membrane proteins of root, stem, and leaf tissues of S. plumbizincicola seedlings treated with Cd solution for 0, 1 or 4 days were analyzed by Tandem Mass Tag (TMT) labeling-based proteome quantification (Data are available via ProteomeXchange with identifier PXD025302). Total 3353 proteins with predicted transmembrane helices were identified and quantified in at least one tissue group. 1667 proteins were defined as DAPs (differentially abundant proteins) using fold change >1.5 with p-values <0.05. The number of DAPs involved in metabolism, transport protein, and signal transduction was significantly increased after exposure to Cd, suggesting that the synthesis and decomposition of organic compounds and the transport of ions were actively involved in the Cd tolerance process. The number of up-regulated transport proteins increased significantly from 1-day exposure to 4-day exposure, from 5 to 112, 16 to 42, 18 to 44, in root, stem, and leaf, respectively. Total 352 Cd-regulated transport proteins were identified, including ABC transporters, ion transport proteins, aquaporins, proton pumps, and organic transport proteins. Heterologous expression of SpABCB28, SpMTP5, SpNRAMP5, and SpHMA2 in yeast and subcellular localization showed the Cd-specific transport activity. The results will enhance our understanding of the molecular mechanism of Cd hypertolerance and hyperaccumulation in S. plumbizincicola and will be benefit for future genetic engineering in phytoremediation.

Isolation and Identification of the Plant Endophyte R-13 and Its Effect on Cadmium Accumulation in Solanum nigrum L.

The combination of endophytes and hyperaccumulator plants can significantly improve the efficiency of heavy metal phytoremediation in contaminated soil. A plant endophyte named Herbaspirillum R-13 was isolated from rice roots in a cadmium (Cd) contaminated paddy field. This strain exhibited a strong tolerance to Cd2+ and could grow on a solid medium with a Cd2+ concentration of 300 mg·kg-1. The R-13 strain was able to produce siderophores and Indole acetic acid (IAA), through color reactions. In addition, Pikovskaya's and Ashby's solid medium tests showed that the R-13 strain had a lower capacity for dissolving phosphorus but a higher capacity for fixing nitrogen. In the pot experiment, high-throughput sequencing technology was used to track the colonization of the R-13 strain in Solanum nigrum L. roots. Three days after inoculation, the relative abundance of Herbaspirillum in the root of Solanum nigrum L. had increased by 201.88% compared to the blank control (CK) and after two inoculations, the relative abundance of Herbaspirillum in the root of Solanum nigrum L. had increased by 1182.44% compared to CK. The relative abundance of Herbaspirillum in the root of Solanum nigrum L. began to decrease significantly from 5 days after inoculation. Inoculation with 20 mL·pot-1 of R-13 fermentation broth resulted in no significant effects on the Cd content of roots, stems, leaves, or fruits of S. nigrum L. With 40 mL·pot-1 of fermentation broth, the Cd content of vegetative organs and fruits was significantly increased. When it reached 200 mL·pot-1, the Cd content of vegetative organs was the highest, with Cd concentrations in the roots, stems, leaves, and fruits increasing by 84.42%, 43.67%, 64.06%, and 20.29%, respectively. In conclusion, root inoculation with endophytic Herbaspirillum R-13 can significantly increase the relative content of Herbaspirillum in the root system and enhance Cd absorption of S. nigrum L. Therefore, this strain has excellent prospects for application in the phytoremediation of soil contaminated with Cd.

Effects of intercropping with Solanum photeinocarpum and its post-grafting generations on cadmium accumulation in loquat (Eriobotrya japonica)

Cadmium (Cd) contamination of orchard soils is a global problem that has been increasing. To decrease the Cd accumulation in fruits, intercropping the orchard crops with hyperaccumulator plants has been used for soil remediation. A pot and a field experiment were conducted to study the effects of intercropping the potential Cd-hyperaccumulator Solanum photeinocarpum and its post-grafting generations with loquat (Eriobotrya japonica) on the growth and Cd uptake of these two plant species. In the pot experiment, intercropping improved the biomass, Cd content, Cd extraction, and root-to-shoot Cd translocation in both species. Intercropping increased the DNA methylation levels, antioxidant enzyme activity, and soluble protein content of loquat seedlings. These results indicate that intercropping could improve the phytoremediation of S. photeinocarpum and its post-grafting generations and increase the Cd uptake in loquat seedlings. In the field experiment, intercropping increased the Cd contents in the old branches, while it decreased that in the young branches and fruits of loquat. These findings indicate that intercropping could increase the Cd uptake in old tissues but reduce the Cd uptake in young tissues and fruits of loquat. So, intercropping loquat with S. photeinocarpum and its post-grafting generations could be used in Cd-contaminated orchards.

Phenotype Switching in Metal-Tolerant Bacteria Isolated from a Hyperaccumulator Plant.

Simple SummaryAzolla filiculoides L. is an aquatic fern with the potential for degradation and accumulation of pollutants. It is accompanied by microorganisms (a microbiome) that may participate in these processes. Microorganisms showing specific phenotypes may promote plant growth in the presence of pollutants. We intended to identify such beneficial strains by studying their potential for the degradation of given organic compounds and the production of hydrolytic enzymes and phytohormones under heavy metal stress (Pb, Cd, Cr (VI), Ni, Ag, and Au). We found 10 isolates displaying varying phenotypes depending on the stress factor. The most efficient was Delftia sp., which showed potential for both degradation of organics and plant growth promotion. Other strains were more efficient at metabolizing organics or exhibited enzymatic responses in the presence of the studied metals. These identified phenotypes made all strains beneficial in both supporting plants in unfavorable conditions and degradation of organic compounds. A biopreparation containing these strains may be valuable as both a biofertilizer and a bioremediation agent.As an adaptation to unfavorable conditions, microorganisms may represent different phenotypes. Azolla filiculoides L. is a hyperaccumulator of pollutants, but the functions of its microbiome have not been well recognized to date. We aimed to reveal the potential of the microbiome for degradation of organic compounds, as well as its potential to promote plant growth in the presence of heavy metals. We applied the BiologTM Phenotypic Microarrays platform to study the potential of the microbiome for the degradation of 96 carbon compounds and stress factors and assayed the hydrolytic potential and auxin production by the microorganisms in the presence of Pb, Cd, Cr (VI), Ni, Ag, and Au. We found various phenotype changes depending on the stress factor, suggesting a possible dual function of the studied microorganisms, i.e., in bioremediation and as a biofertilizer for plant growth promotion. Delftia sp., Staphylococcus sp. and Microbacterium sp. exhibited high efficacy in metabolizing organic compounds. Delftia sp., Achromobacter sp. and Agrobacterium sp. were efficient in enzymatic responses and were characterized by metal tolerant. Since each strain exhibited individual phenotype changes due to the studied stresses, they may all be beneficial as both biofertilizers and bioremediation agents, especially when combined in one biopreparation.

Arabidopsis thaliana Zn2+-efflux ATPases HMA2 and HMA4 are required for resistance to the necrotrophic fungus Plectosphaerella cucumerina BMM.

Zinc is an essential nutrient at low concentrations, but toxic at slightly higher ones. It has been proposed that hyperaccumulator plants may use the excess zinc to fend off pathogens and herbivores. However, there is little evidence of a similar response in other plants. Here we show that Arabidopsis thaliana leaves inoculated with the necrotrophic fungus Plectosphaerella cucumerina BMM (PcBMM) accumulate zinc and manganese at the infection site. Zinc accumulation did not occur in a double mutant in the zinc transporters HEAVY METAL ATPASE2 and HEAVY METAL ATPASE4 (HMA2 and HMA4), which has reduced zinc translocation from roots to shoots. Consistent with a role in plant immunity, expression of HMA2 and HMA4 was up-regulated upon PcBMM inoculation, and hma2hma4 mutants were more susceptible to PcBMM infection. This phenotype was rescued upon zinc supplementation. The increased susceptibility to PcBMM infection was not due to the diminished expression of genes involved in the salicylic acid, ethylene, or jasmonate pathways since they were constitutively up-regulated in hma2hma4 plants. Our data indicate a role of zinc in resistance to PcBMM in plants containing ordinary levels of zinc. This layer of immunity runs in parallel to the already characterized defence pathways, and its removal has a direct effect on resistance to pathogens.

Competition for light induces metal accumulation in a metal hyperaccumulating plant.

Plants can respond to competition with a myriad of physiological or morphological changes. Competition has also been shown to affect the foraging decisions of plants belowground. However, a completely unexplored idea is that competition might also affect plants' foraging for specific elements required to inhibit the growth of their competitors. In this study, we examined the effect of simulated competition on root foraging and accumulation of heavy metals in the metal hyperaccumulating perennial plant Arabidopsis halleri, whose metal accumulation has been shown to provide allelopathic ability. A. halleri plants originating from both metalliferous and non-metalliferous soils were grown in a "split-root" setup with one root in a high-metal pot and the other in a low-metal one. The plants were then assigned to either simulated light competition or no-competition (control) treatments, using vertical green or clear plastic filters, respectively. While simulated light competition did not induce greater root allocation into the high-metal pots, it did result in enhanced metal accumulation by A. halleri, particularly in the less metal-tolerant plants, originating from non-metalliferous soils. Interestingly, this accumulation response was particularly enhanced for zinc rather than cadmium. These results provide support to the idea that the accumulation of metals by hyperaccumulating plants can be facultative and change according to their demand following competition.

Efficiency of transporter genes and proteins in hyperaccumulator plants for metals tolerance in wastewater treatment: Sustainable technique for metal detoxification

Environmental contamination of heavy metals is now becoming increasingly a concern and a significant problem due to its harmful effects worldwide. The plant-meditated approach is encouraging to eliminate toxins avoiding side effects from polluted wastewater. For the development of appropriate plant species for the mechanisms of heavy metal absorption, transport, detoxification, identification, and signaling pathways would be important facts. Transporter genes like ATP-phosphoribosyl transferase (ATP-PRT), Yellow Stripe-like (YSL), NAS (nicotinamide synthase), SAMS (S-adenosyl-methionine synthetase), FER (ferritin Fe (III) binding), HMA (heavy metal ATPase), IREG (iron-regulated transporter), and proteins like cation diffusion facilitators (CDF), ZRT, IRT-like protein (ZIP), and natural resistance-associated macrophage protein (NRAMP) are active in heavy metal accumulation, translocalisation, sequestration, and resistance. Besides, chelating agents and metabolites can be used either to increase heavy metal bioavailability, which facilitates heavy metal accumulation in plants and further promote plant growth and fitness. This review paper addresses key roles and potential transporter genes and proteins for the remediation of heavy metals from hyperaccumulator plants. This review specifically focuses on the efficacy of transporter genes and proteins in hyperaccumulator plants in metal restoration, discussing the use of these plants for wastewater treatment processes. • Discusses the efficiency of hyperaccumulator plant for removal of metals. • Summarizes transporter gene and proteins in heavy metal uptake and tolerance. • Proposes improved prospects for wastewater treatment.

Bioaugmentation with As-transforming bacteria improves arsenic availability and uptake by the hyperaccumulator plant Pteris vittata (L).

Inorganic arsenic (As) is a toxic and carcinogenic pollutant that has long-term impacts on environmental quality and human health. Pteris vittata plants hyperaccumulate As from soils. Soil bacteria are critical for As-uptake by P. vittata. We examined the use of taxonomically diverse soil bacteria to modulate As speciation in soil and their effect on As-uptake by P. vittata. Aqueous media inoculated with Pseudomonas putida MK800041, P. monteilii MK344656, P. plecoglossicida MK345459, Ochrobactrum intermedium MK346993 or Agrobacterium tumefaciens MK346997 resulted in the oxidation of 5–30% As(III) and a 49–79% reduction of As(V). Soil inoculated with P. monteilii increased extractable As(III) and As(V) from 0.5 and 0.09 in controls to 0.9 and 0.39 mg As kg−1 soil dry weight, respectively. Moreover, and P. vittata plants inoculated with P. monteilii, P. plecoglossicida, O. intermedium strains, and A. tumefaciens strains MK344655, MK346994, MK346997, significantly increased As-uptake by 43, 32, 12, 18, 16, and 14%, respectively, compared to controls. The greatest As-accumulation (1.9 ± 0.04 g kg−1 frond Dwt) and bioconcentration factor (16.3 ± 0.35) was achieved in plants inoculated with P. monteilii. Our findings indicate that the tested bacterial strains can increase As-availability in soils, thus enhancing As-accumulation by P. vittata. Novelty statement Pteris vittata, a well-known As-hyperaccumulator, has the remarkable ability to accumulate higher levels of As in their above-ground biomass. The As-tolerant bacteria-plant interactions play a significant role in bioremediation by mediating As-redox and controlling As-availability and uptake by P. vittata. Our studies indicated that most of the tested bacterial strains isolated from As-impacted soil significantly enhanced As-uptake by P. vittata. P. monteilii oxidized 20% of As(III) and reduced 50% of As(V), increased As-extraction from soils, and increased As-uptake by 43% greater compared with control. Therefore, these strains associated with P. vittata can be used in large-scale field applications to remediate As-contaminated soil.

Plant–microbe–metal interactions for heavy metal bioremediation: a review

Considerable amounts of heavy metals have contaminated the soil from potential manmade point and non-point sources such as industry, urbanisation and agriculture. In both managed and natural ecosystems, beneficial plant–microbe interactions play a significant role improving the growth and health of plants, and could be applied for improving soil fertility as well as crop productivity. Additionally, plant–microbe interactions could be utilised in bioremediation of heavy metal-contaminated soils. The efficiency of phytoremediation can be improved with the aid of plant-growth-promoting bacteria (PGPB), which can change metals to bioavailable and soluble forms. PGPB perform remediation through processes such as production of siderophores, organic acids and biosurfactants, biomethylation, redox processes, phosphorus solubilisation, nitrogen fixation and iron sequestration. These processes improve plant growth and increase plant biomass along with phytoremediation. A crucial solution to the problem of heavy metal contamination might be an appropriate understanding of hyperaccumulator plants and their interaction with microbes. Emerging strategies for either enhancing or reducing the bioavailability of heavy metals in the rhizosphere, such as improving plant establishment, growth and health can significantly accelerate the heavy metal bioremediation process. In this review, we feature the function of PGPB to assist phytoremediation of heavy metals as an eco-friendly and economical approach.

Scope and future perspectives of phytoremediation

Phytoremediation is the plant-based technology that has emerged as a novel cost effective and ecofriendly technology in which green plants are used for extraction, sequestration and/or detoxification of the pollutants. Plants possess the natural ability to degrade heavy metals and this property of plants to detoxify contaminants can be used by genetic engineering approach. Currently, the quality of soil and water has degraded considerably due heavy metal accumulation through discharge of industrial, agricultural and domestic waste. Heavy metal pollution is a global concern and a major health threat worldwide. They are toxic, and can damage living organisms even at low concentrations and tend to accumulate in the food chain. The most common heavy metal contaminants are: As, Cd, Cr, Cu, Hg, Pb and Zn. High levels of metals in soil can be phytotoxic, leading to poor plant growth and soil cover due to metal toxicity and can lead to metal mobilization in runoff water and thus have a negative impact on the whole ecosystem. Phytoremediation is a green strategy that uses hyperaccumulator plants and their rhizospheric micro-organisms to stabilize, transfer or degrade pollutants in soil, water and environment. Mechanisms used to remediate contaminated soil includes phytoextraction, phytostabilization, phytotransformation, phytostimulation, phytovolatilization and rhizofiltration. Traditional phytoremediation method presents some limitations regarding their applications at large scale, so the application of genetic engineering approaches such as transgenic transformation, nanoparticles addition and phytoremediation assisted with phytohormones, plant growth-promoting bacteria and Arbuscular mycorrhizal fungi (AMF) inoculation has been applied to ameliorate the efficacy of plants for heavy metals decontamination. In this review, some recent innovative technologies for improving phytoremediation and heavy metals toxicity and their depollution procedures are highlighted.

New evidence of arsenic translocation and accumulation in Pteris vittata from real-time imaging using positron-emitting 74As tracer

Pteris vittata is an arsenic (As) hyperaccumulator plant that accumulates a large amount of As into fronds and rhizomes (around 16,000 mg/kg in both after 16 weeks hydroponic cultivation with 30 mg/L arsenate). However, the sequence of long-distance transport of As in this hyperaccumulator plant is unclear. In this study, we used a positron-emitting tracer imaging system (PETIS) for the first time to obtain noninvasive serial images of As behavior in living plants with positron-emitting 74As-labeled tracer. We found that As kept accumulating in rhizomes as in fronds of P. vittata, whereas As was retained in roots of a non-accumulator plant Arabidopsis thaliana. Autoradiograph results of As distribution in P. vittata showed that with low As exposure, As was predominantly accumulated in young fronds and the midrib and rachis of mature fronds. Under high As exposure, As accumulation shifted from young fronds to mature fronds, especially in the margin of pinna, which resulted in necrotic symptoms, turning the marginal color to gray and then brown. Our results indicated that the function of rhizomes in P. vittata was As accumulation and the regulation of As translocation to the mature fronds to protect the young fronds under high As exposure.

Molecular identification and evaluation of gamma irradiation effect on modulating heavy metals tolerance in some of novel endophytic fungal strains

Heavy metal (HM) pollution is a worldwide environmental issue. Given the urgent need to develop more powerful approaches for effective phytoremediation of HMs, isolation of novel endophytic strains from hyperaccumulator plants having potent HM tolerance is the main objective in this research. Moreover, the recovered strains were characterized and subjected to radiation mutagenesis to enhance their tolerance to HMs. Among 105 isolates, Alternaria alternata AUMC14431 was identified as the most effective Cd+2 tolerant strain having high recorded tolerance index (TI) (76.24%); in addition, the recorded minimum inhibitory concentration (MIC) was 300ppm. Meanwhile, Chaetomium globosum AUMC14432 was identified as the most effective Pb+2 and Ni+2 tolerant strain having high recorded TI (97.46 and 93.34%, respectively); in addition, the evaluated MICs were 250 and 200ppm, respectively. UV and gamma irradiation of the tested strains enhanced their Cd+2 and Pb+2 tolerance significantly (P ≤ 0.05). Meanwhile, irradiation had a negative impact on Ni+2 tolerance of C. globosum. The mutation incidence at the molecular level arising from exposure to irradiation was investigated. Genomic DNA of both the wild and mutated endophytic strains were isolated followed by random amplified polymorphic DNA (RAPD-PCR) analysis, using two short primers. A remarkable difference in DNA gel pattern between the wild type and mutated strains was observed. In conclusion, the novel isolated and irradiated endophytic strains, A. alternata S5 and C. globosum El26, having high efficiency in Cd+2 and Pb+2 tolerance, respectively, are considered to be prospective and powerful bioremediation candidates for potential application in microbially assisted phytoremediation.

Phytoextraction efficiency of Arabidopsis halleri is driven by the plant and not by soil metal concentration

The hyperaccumulation trait allows some plant species to allocate remarkable amounts of trace metal elements (TME) to their foliage without suffering from toxicity. Utilizing hyperaccumulating plants to remediate TME contaminated sites could provide a sustainable alternative to industrial approaches. A major hurdle that currently hampers this approach is the complexity of the plant-soil relationship. To better anticipate the outcome of future phytoremediation efforts, we evaluated the potential for soil metal-bioavailability to predict TME accumulation in two non-metallicolous and two metallicolous populations of the Zn/Cd hyperaccumulator Arabidopsis halleri. We also examined the relationship between a population's habitat and its phytoextraction efficiency. Total Zn and Cd concentrations were quantified in soil and plant material, and bioavailable fractions in soil were quantified via Diffusive Gradients in Thin-films (DGT). We found that shoot TME accumulation varied independent from both total and bioavailable soil TME concentrations in metallicolous individuals. In fact, hyperaccumulation patterns appear more plant- and less soil-driven: one non-metallicolous population proved to be as efficient in accumulating Zn on non-polluted soil as the metallicolous populations in their highly contaminated environment. Our findings demonstrate that in-situ information on plant phytoextraction efficiency is indispensable to optimize site-specific phytoremediation measures. If successful, hyperaccumulating plant biomass may provide valuable source material for application in the emerging field of green chemistry.

ARPA–E explores paths to emissions-free metal making

The agency is seeking advice from industry and academia on how to make mining, smelting, and remediation less polluting and more energy efficient.

Phytoremediation-a sustainable remedial method for soil contaminated by vanadium

Vanadium amassing in the soil increased with its widespread usage in multi-field. Elevated soil vanadium confers adverse effects on living organisms involved in plants, animals, and microorganisms. Moreover, vanadium can enter the human body through the food chain and lead to potential health risks stemming from its toxicity and carcinogenicity. Therefore, the remediation of soil contaminated by vanadium is imperative. Phytoremediation, a clean phytotechnology, is gaining increasing grace in modern society that prefers spirit-enjoy persuing. However, due to the blemishes of the remediation plants per se, the remediation efficiency relying on plants alone is not attractive. Therefore, the strengthened screening of vanadium accumulator and hyperaccumulator plants should step forward. Simultaneously, it is necessary to improve phytoremediation efficiency by some complementary measures, such as inoculating plant growth-promoting bacteria, vanadium reducing bacteria, and the proper application of plant growth regulators. Overall, microbe-assisted and moderate usage of plant growth-promoting factors are promising for the phytoremediation of vanadium-contaminated soil.

Sauaeda Fruticusa is Hyperaccumulator of Chromium and Lead

Sauaeda Fruticusa is Hyperaccumulator of Chromium and Lead

Lead removal from soil by phytoremediation method

Many control approaches are used today to prevent the contamination of soils with heavy metals and to remove pollution. One of these approaches is phytoremediation for the on-site treatment of pollutants. In phytoremediation, hyperaccumulator plants are used, which absorb heavy metals, accumulate at high levels in their tissues, and neutralize them after various processes. It was aimed to determine the effects of heavy metals on plant growth and the heavy metal accumulation capacity of plants in this study. Using the phytoremediation method, the growth process of the canola plant and its lead removal capacity from the soil were investigated. The study was carried out in 3 replicates by watering the plants only with tap water and tap water containing different concentrations of lead in greenhouse conditions. The prepared soil mixture was placed in pots as 2000 g pot-1. The sown seeds were germinated using tap water in the plant growing room and the water requirement of the plants was met with tap water containing a certain concentration of lead during the next growing period. Plants were harvested at the end of the 3 month growth period. The plants irrigated with the lead solution were compared only with the plants irrigated with tap water, and the elongation amounts of root and stem lengths were determined. Plant samples with dry weights determined were burned with certain chemicals using the microwave method, and then the amount of lead in the plants was measured with the ICP-MS device.

Ecology as a Tool to Assist Conservation of a Rare and Endemic Mediterranean Plantago Species

Reviewing the ecological studies on the endangered endemic Plantago almogravensis Franco, an Al-hyperaccumulator plant, and combining these with morphological, physiological, biochemical, and molecular data, significant knowledge on the limiting factors that cause its narrow geographical distribution and rarity status is achieved, which can contribute to suited conservation guidelines. Emphasis was given on (i) the major factors limiting P. almogravensis’ ecological niche (biotic and abiotic); (ii) phases of the life cycle and population dynamics; and (iii) and the phylogenetically close taxa (Plantago subulata aggregate) in order to fill the knowledge gaps in the uniqueness of P. almogravensis ecology, its phylogeny, and conservation status. The identification of relevant ecological data and using plant functional (morphological and physiological) traits, as well as genetic attributes, substantiate into a powerful tool to guide protection and conservation measures, usable toward this and other endangered hyperaccumulator plant species. Knowledge of the limitations of this strongly narrowly distributed plant allows for better design of conservation measures and to guide value and investment strategies in order to secure the species’ current area (habitat conservation and reclamation), direct the expansion of the existing population (assisting in populational densification and colonization), and/or grant ex situ conservation (genetic resources conservation).

The Role of Microorganisms in Mobilization and Phytoextraction of Rare Earth Elements: A Review

Rare earth (RE) elements are a group of 17 chemical elements including the 15 lanthanides plus Yttrium and Scandium. RE have been identified as critical elements due to their special properties (e.g., catalytic, metallurgical, nuclear, electrical, magnetic, and luminescent) and various applications in many modern technologies, environment and economic areas. Thus, the demand for RE has increased significantly during the last decades. This demand has induced an increase in mining activities and consequently a release of RE into the surrounding environment, causing a potential threat to human health and the environment. Therefore, investigations leading to new solutions for the RE recycling from alternate resources like electronic, mining and industrial wastes, has been rapidly growing. In spite of that, recycling stays extremely difficult, expensive and is currently not seen as a significant solution. The concept of phytomanagement is a promising solution when conventional mining methods are no longer cost-effective, not to mention all the ecosystem services provided by plants. The phytoextraction service allows the extraction and recovery of RE from soils or industrial wastes (e.g., phosphogypsum from phosphoric acid production) with the prospect of economic added value. To date, some twenty hyperaccumulator plant species (almost ferns such as Dicranopteris dicthotoma) accumulate high concentrations of RE especially in their erial parts. While the potential roles of native bacteria in mobilization of RE from ores remains slightly documented, those of Plant Growth Promoting Rhizobacteria (PGPR) is much less. PGPR are indeed able to mobilize metals and/or to stimulate plant development in the aim to increase the amount of RE extracted by the plant with then a higher phytoextraction efficiency. Yet to date, only a few studies have been devoted to RE using coupled bioaugmentation-phytoextraction. This review summarizes the data regarding 1) the source of RE (RE-accumulating sediments, soils naturally rich in RE, wastes) and their bioavailability in these matrices, 2) plants identified as RE hyperaccumulator and their potential for RE phytomining, 3) isolation and selection of indigenous bacteria stemming from RE contaminated matrices, such as soil, for their potential ability to increase phytoextraction performances and 4) bioaugmentation-assisted phytoextraction studies dealing with RE.

Comparative transcriptome analysis of the hyperaccumulator plant Phytolacca americana in response to cadmium stress.

The online version contains supplementary material available at 10.1007/s13205-021-02865-x.