Phytoremediation Of Heavy Metals Research Articles

Cadmium (Cd) Tolerance and Phytoremediation Potential in Fiber Crops: Research Updates and Future Breeding Efforts

Heavy metal pollution is one of the most devastating abiotic factors, significantly damaging crops and human health. One of the serious problems it causes is a rise in cadmium (Cd) toxicity. Cd is a highly toxic metal with a negative biological role, and it enters plants via the soil–plant system. Cd stress induces a series of disorders in plants’ morphological, physiological, and biochemical processes and initiates the inhibition of seed germination, ultimately resulting in reduced growth. Fiber crops such as kenaf, jute, hemp, cotton, and flax have high industrial importance and often face the issue of Cd toxicity. Various techniques have been introduced to counter the rising threats of Cd toxicity, including reducing Cd content in the soil, mitigating the effects of Cd stress, and genetic improvements in plant tolerance against this stress. For decades, plant breeders have been trying to develop Cd-tolerant fiber crops through the identification and transformation of novel genes. Still, the complex mechanism of Cd tolerance has hindered the progress of genetic breeding. These crops are ideal candidates for the phytoremediation of heavy metals in contaminated soils. Hence, increased Cd uptake, accumulation, and translocation in below-ground parts (roots) and above-ground parts (shoots, leaves, and stems) can help clean agricultural lands for safe use for food crops. Earlier studies indicated that reducing Cd uptake, detoxification, reducing the effects of Cd stress, and developing plant tolerance to these stresses through the identification of novel genes are fruitful approaches. This review aims to highlight the role of some conventional and molecular techniques in reducing the threats of Cd stress in some key fiber crops. Molecular techniques mainly involve QTL mapping and GWAS. However, more focus has been given to the use of transcriptome and TFs analysis to explore the potential genomic regions involved in Cd tolerance in these crops. This review will serve as a source of valuable genetic information on key fiber crops, allowing for further in-depth analyses of Cd tolerance to identify the critical genes for molecular breeding, like genetic engineering and CRISPR/Cas9.

Potential of Selected Species of Spiraea L. for Phytoremediation of Heavy Metals from Soils of Urban Areas

Four taxa of Spiraea were selected for this study: S. × cinerea Zabel ‘Grefsheim’, S. nipponica Maxim. ‘Snowmound’, S. splendens É. N. Baumann ex K. Koch and S. × vanhouttei (Briot) Carrière growing for a minimum of 5 years along heavily trafficked traffic routes. This study included the genus Spiraea due to its popularity in horticultural practice (commercial availability, widespread in urban environments). In addition, the use of ornamental shrubs for phytoremediation in urban green spaces effectively combines the aesthetic needs of residents with those of caring for the urban environment. This study was conducted in Poznań (population 550,000, the fifth largest city in Poland). Soils and foliage were examined in spring and autumn. Soil pH and specific electrolytic conductivity (EC) were determined. The content of micronutrients (Cu, Fe, Mn, Ni, Zn) and toxic heavy metals (Cd, Cr, Pb) in soil dry matter and leaves was determined. The uptake capacity of bioavailable forms of heavy metals by Spiraea from the soil was analyzed by determining the bioconcentration factor (BCF). It was found that the studied taxa meet the basic requirements for plants used for soil phytoremediation processes, especially for chromium phytoextraction. The degree of salinity of the tested soils did not pose a threat to the shrubs growing there, and most of the sites, despite the alkaline reaction, are suitable for their cultivation. S. × cinerea and S. × vanhouttei have BCFs for lead <1. The remaining taxa are characterized by strong concentrations of all analyzed elements. A particularly high BCF, above 10, was recorded for chromium and high for manganese and nickel.

Capacity of an aquatic macrophyte, Pistia stratiotes L., for removing heavy metals from water in the Oued Fez River and their accumulation in its tissues.

Water resources, particularly rivers, are increasingly exposed to pollutants, especially heavy metals of chemical origin, which are difficult to monitor and can pose risks to both ecosystems and human health. This study assesses heavy metal contamination in the Oued Fez River, focusing on the bioaccumulation by the invasive plant Pistia stratiotes. The methodology involves measuring and comparing metal concentrations in water and plant tissues. Results revealed that while aluminium (Al) slightly exceeded recommended levels at 0.2978 mg L-1, other metals like zinc (Zn), iron (Fe), copper (Cu), lead (Pb) and cadmium (Cd) remained within acceptable limits. The study demonstrates P. stratiotes' effectiveness in heavy metal phytoremediation, with its roots showing high bioaccumulation up to 19,726 mg kg-1 for Fe and 15,128 mg kg-1 for Al, indicating its potential for water decontamination. Eco-toxicological assessments, including bioconcentration and translocation factors, confirm the plant's capacity to mobilize toxic metals. Statistical analysis also points to possible industrial, urban, or agricultural contamination sources based on correlations between Al, Fe and Zn. The study underscores P. stratiotes' role in phytoremediation while emphasizing the need for monitoring and controlling contamination sources and managing the spread of this invasive species to ensure sustainable water resources.

Enhancing the Phytoremediation of Heavy Metals by Plant Growth Promoting Rhizobacteria (PGPR) Consortium: A Narrative Review.

Heavy metal pollution has become a significant concern as the world continues to industrialize, urbanize, and modernize. Heavy metal pollutants impede the growth and metabolism of plants. The bioaccumulation of heavy metals in plants may create chlorophyll antagonism, oxidative stress, underdeveloped plant growth, and reduced photosynthetic system. Finding practical solutions to protect the environment and plants from the toxic effects of heavy metals is essential for long-term sustainable development. The direct use of suitable living plants for eliminating and degrading metal pollutants from ecosystems is known as phytoremediation. Phytoremediation is a novel and promising way to remove toxic heavy metals. Plant growth-promoting rhizobacteria (PGPR) can colonize plant roots and help promote their growth. Numerous variables, such as plant biomass yield, resistance to metal toxicity, and heavy metal solubility in the soil, affect the rate of phytoremediation. Phytoremediation using the PGPR consortium can speed up the process and increase the rate of heavy metal detoxification. The PGPR consortium has significantly increased the biological accumulation of various nutrients and heavy metals. This review sheds light on the mechanisms that allow plants to uptake and sequester toxic heavy metals to improve soil detoxification. The present review aids the understanding of eco-physiological mechanisms that drive plant-microbe interactions in the heavy metal-stressed environment.

Biochar influences phytoremediation of heavy metals in contaminated soils: an overview and perspectives.

Heavy metals (HMs) contamination has gained much attention due to its high degree of toxicity for living organisms. Therefore, different techniques are underway to eradicate HMs from the environment. Among the biological techniques, phytoremediation is a suitable method, but owing to the slow rate and chance of HMs penetration into the food chain, alternative techniques are needed to reduce their phytotoxicity, and biochar is one of them. Due to the diverse characteristics, biochar immobilizes HMs in the soil by improving soil pH, ion exchange, electrostatic interactions, complexation, precipitation, surface adsorption, and microbial activation. Thereby, amendment of biochar in the HMs-contaminated soils reduces HMs toxicity to plants and limits their penetration into the food chain. In contrast, some biochars have also been studied to induce metal availability in soils and subsequently its uptake by plants. This dual role of biochar depends on the feedstock of biochar, incineration temperature, and the rate of application. Moreover, biochar treatments enhance plant growth under HMs stress by improving nutrient availability, water retention capacity, scavenging of reactive oxygen species, and photosynthetic efficiency. Owing to the beneficial characteristics of biochar in HMs-contaminated sites, the number of publications has tremendously increased. Additionally, the plant species and the types of HMs that have been tested frequently under biochar treatments in these articles have been studied. Overall, the current study would help in understanding the mechanisms of how biochar influences phytoremediation of HMs and improves plant growth in HMs-polluted soils and the current scenario of the available literature.

Evaluation of the effectiveness of Azolla fern in removing the toxicity of lead and cadmium in water

Background: Heavy metals are harmful to living organisms and are emitted into the environment from many different sources. Compared to alternative remediation technologies that are either too expensive or impractical, phytoremediation, in which plants are used to remove hazardous toxins from water and soil, is a viable option for use at extremely large field sites. Heavy metals may be removed from the environment by a wide variety of plants. Azolla, a kind of aquatic fern, is one example.Methods: Different concentrations of heavy elements (5,10, and 25mg/ L) were prepared and treated with the plant in different masses (0.2,0.4, and 0.8 grams)and over time periods of one and two weeks. The concentration of each element was measured before and after the treatment periods using an atomic absorption device.Results: As evidenced that spring Azolla (green type) was more effective at removing cadmium and lead elements than autumn Azolla (red type), where the spring Azolla recorded higher removal efficiency for Cd , where it was 1.80% under biomass 0.8g, contact time 10 days, and at metal concentration 10mg\L ,while the highest percentage removal for Pb , was 40.02% under biomass 0.4g, contact time 15 day and at metal concentration 5mg\L . Azolla has great potential for removing heavy metals from water resources and can be used in heavy metal phytoremediation initiatives in environmental improvement projects.Conclusion: This research suggests using the aquatic macrophyte Azolla, especially spring fern, to treat sewage and household wastewater containing Cadmium and Lead.Keywords: Azolla; Heavy metals; Phytoremediation; Cd; Pb

Assessment of selected tree species as phytoremediation agents in polluted soils

The study investigates the ability of selected tree species to absorb heavy metals (Pb, Ni, Zn) from polluted soils. Seedlings of Adansonia digitata (P1), Jatropha curcas (P2), and Hildegardia barteri (P3) were transplanted into polythene pots with soils from a dumpsite (T1), highway (T2), industrial area (T3), and farmland (T4), forming a 3x4 factorial experiment replicated five times in a Completely Randomized Block Design. Pre-sowing analysis showed T1 and T2 had the highest Pb and Zn concentrations, T3 had the highest Ni, and T4 had the lowest heavy metal concentrations. After 12 weeks, heavy metal concentrations decreased in all soils. P1 concentrated metals in the root, P2 in the shoot, and P3 in various plant parts, with significant differences between species. P2 was identified as an effective phytoextractor for Pb and Zn (TF > 1), and P3 for Ni. All species showed potential for phytostabilization. The study concludes that these species are viable options for phytoremediation of heavy metals in contaminated soils.

Phytoremediation of Heavy Metals Polluted Soil from the Etelebou Dumpsite in Yenagoa, Bayelsa State, Nigeria

Phytoremediation of Heavy Metals Polluted Soil from the Etelebou Dumpsite in Yenagoa, Bayelsa State, Nigeria

Invasive Amaranthus spp. for heavy metal phytoremediation: Investigations of cadmium and lead accumulation and soil microbial community in three zinc mining areas

Amaranthus spp. are a group of strongly invasive and vigorous plants, and heavy metal phytoremediation using alien invasive Amaranthus spp. has been a popular research topic. In this study, the bioconcentration factor (BCF) and translocation factor (TF) of Amaranthus spp. were evaluated, focusing on the accumulation potential of cadmium (Cd) and lead (Pb) by plants from three different zinc mining areas, namely Huayuan (HYX), Yueyang (LYX), and Liuyang (LYX). The HYX area has the most severe Cd contamination, while the LYX area has the most apparent Pb contamination. The results showed that Amaranthus spp. had a strong Cd and Pb enrichment capacity in low-polluted areas. To elucidate the underlying mechanisms, we used high-throughput sequencing of 16S rRNA and internal transcribed spacer (ITS) regions to analyze rhizosphere bacterial and fungal communities in three areas. The results showed significant differences in the structure, function, and composition of microbial communities and complex interactions between plants and their microbes. The correlation analysis revealed that some key microorganisms (e.g., Amycolatopsis, Bryobacterium, Sphingomonas, Flavobacterium, Agaricus, Nigrospora, Humicola) could regulate several soil factors such as soil pH, organic matter (OM), available nitrogen (AN), and available phosphorus (AP) to affect the heavy metal enrichment capacity of plants. Notably, some enzymes (e.g., P-type ATPases, Cysteine synthase, Catalase, Acid phosphatase) and genes (e.g., ZIP gene family, and ArsR, MerR, Fur, NikR transcription regulators) have been found to be involved in promoting Cd and Pb accumulation in Amaranthus spp. This study can provide new ideas for managing heavy metal-contaminated soils and new ways for the ecological resource utilization of invasive plants in phytoremediation.

Plant growth-promoting rhizobacterial secondary metabolites in augmenting heavy metal(loid) phytoremediation: An integrated green in situ ecorestorative technology.

In recent times, increased geogenic and human-centric activities have caused significant heavy metal(loid) (HM) contamination of soil, adversely impacting environmental, plant, and human health. Phytoremediation is an evolving, cost-effective, environment-friendly, in situ technology that employs indigenous/exotic plant species as natural purifiers to remove toxic HM(s) from deteriorated ambient soil. Interestingly, the plant's rhizomicrobiome is pivotal in promoting overall plant nutrition, health, and phytoremediation. Certain secondary metabolites produced by plant growth-promoting rhizobacteria (PGPR) directly participate in HM bioremediation through chelation/mobilization/sequestration/bioadsorption/bioaccumulation, thus altering metal(loid) bioavailability for their uptake, accumulation, and translocation by plants. Moreover, the metallotolerance of the PGPR and the host plant is another critical factor for the successful phytoremediation of metal(loid)-polluted soil. Among the phytotechniques available for HM remediation, phytoextraction/phytoaccumulation (HM mobilization, uptake, and accumulation within the different plant tissues) and phytosequestration/phytostabilization (HM immobilization within the soil) have gained momentum in recent years. Natural metal(loid)-hyperaccumulating plants have the potential to assimilate increased levels of metal(loid)s, and several such species have already been identified as potential candidates for HM phytoremediation. Furthermore, the development of transgenic rhizobacterial and/or plant strains with enhanced environmental adaptability and metal(loid) uptake ability using genetic engineering might open new avenues in PGPR-assisted phytoremediation technologies. With the use of the Geographic Information System (GIS) for identifying metal(loid)-impacted lands and an appropriate combination of normal/transgenic (hyper)accumulator plant(s) and rhizobacterial inoculant(s), it is possible to develop efficient integrated phytobial remediation strategies in boosting the clean-up process over vast regions of HM-contaminated sites and eventually restore ecosystem health.

Cyperus longus to bioremediate heavy metals in aqueous solutions

Finding environmentally friendly methods for the bioremediation of the environment, including water, contaminated with heavy metals is of utmost significance. The ability of 50 Cyperus longus species, harvested from Shadegan International Wetland, Iran, for the phytoremediation of heavy metals in contaminated water was investigated. The plants were transplanted in the aquariums contaminated with one of the heavy metals (0–20 mgL-1) at the pHs of 4 and 7 for 30 days. Plant removal of heavy metals was determined. The single and double interactions of plant tissue, heavy metal type and concentration, and pH significantly affected the absorption of plant heavy metals. The highest removal of heavy metals including Pb (45.9 %) > Zn (36.1 %) > Cr (32.8 %) > Cd (27.5 %) > Ni (25.9 %) was related to the 20 mgL-1 and pH4 treatments by the order of root> stem> leaf> flower. The 5–10 mgL-1 concentration resulted in the highest removal efficiency by stems (Ni, 44.12 %), flowers (Zn, 44.00 %), leaves (Cr, 44.14 %) and roots (Cr, 44.36 %). The highest bioconcentration (BCF) and translocation factors (TF) of 4.106 and 2 (Zn), 2.124 and 1.461 (Cd), 1.815 and 1.289 (Ni), 5.291 and 2.460 (Pb), and 2.811 and 1.885 (Cr) were resulted. Although with increasing heavy metal concentrations, the plant absorbed higher heavy metals, its removal efficiency decreased as it was the highest at the heavy metal concentration of 5–10 mgL-1. According to plant removal efficiency and the BCF and TF factors, it is possible to efficiently bioremediate water contaminated with heavy metals using C. longus.

Effect of Heavy Metal Phytoremediation on Phytochemical Fingerprint and Bioactivity of Pistia stratiotes: A Quest for Re-routing Disposal to Commercial Application

Phytoremediation is one of the non-energy consuming processes of remediating polluted water. However, the disposal of post-remediated plants poses a threat of the re-introduction of pollutants back into the ecosystem. Re-routing remediated pollutants for commercial application could be one way to reduce the re-introduction of pollutants in an ecosystem. Heavy metal pollution in water bodies is one issue, which can be mitigated to an extent with phytoremediation. In the current study, the effect of heavy metal phytoremediation on the phytochemical fingerprint and bioactivity of Pistia stratiotes L. was investigated. Pistia stratiotes L. was subjected to different concentrations of iron (Fe) and lead (Pb), in the range of 5-20 ppm. Different parameters such as heavy metal estimation (in plants and water post-treatment), thin layer chromatography (TLC), antioxidant activity, and antiurolithic activity were measured. Post remediation, heavy metal concentration was found to be comparatively higher in roots (16.515 ± 0.008 mg.g-1 and 5.25 ± 0.086 mg.g-1 when treated with 15 ppm iron and lead respectively). TLC revealed differences between the fingerprints of treated and untreated plants. Some bands increased in intensity as the concentration of heavy metal increased, while some bands which were present in untreated, were absent in treated plant samples. Antioxidant activity of treated plants shows lesser IC50 values, compared to untreated, in that, treated leaves show better activity (IC50 = 1.8 ± 0.5220 mg.mL-1 of leaf treated with 2 ppm iron as opposed to IC50 > 5 mg.mL-1 of untreated leaf extract). The treated plants revealed good antiurolithic activity compared to untreated, in that, the percentage inhibition showed by Iron treated leaves and roots was better (96.87% and 98.95% exhibited by iron-10 ppm treated leaves and roots respectively), while the untreated showed a maximum of only 68.75% inhibition. The results suggest that the bioactivity of the plant extracts increases post-remediation. Potential applications of these extracts can be explored such as nanoparticle synthesis, drug discovery, etc.

Investigation of Cd and Pb enrichment capacities of Erigeron sumatrensis across three polluted regions: Insights into soil parameters and microbial communities

Erigeron sumatrensis is a vigorously growing invasive plant in mining areas and has been the subject of research for its potential in the phytoremediation of heavy metals. In this study, the bioconcentration factor (BCF) and translocation factor (TF) of E. sumatrensis were assessed to evaluate its phytoaccumulation potential for cadmium (Cd) and lead (Pb) across three distinct zinc mining regions with different degrees of contamination, including Huayuan (HY), Yueyang (YY), and Liuyang (LY) areas. The region of HY is identified as having the most severe Cd contamination, while the most pronounced Pb pollution characterizes the LY area. The findings indicate that E. sumatrensis demonstrated a stronger ability to enrich Cd and Pb in less contaminated areas. To elucidate the underlying mechanisms, high-throughput sequencing of 16S rRNA and internal transcribed spacer (ITS) regions was employed to analyze the rhizosphere bacterial and fungal communities across the three areas. The results revealed significant variations in the microbial community structure, function, and composition, suggesting a complex interplay between the plant and its associated microorganisms. Correlation analysis identified several soil properties, including soil pH, total nitrogen (TN), available nitrogen (AN), organic matter (OM), and available phosphorus (AP), as pivotal factors that may influence the heavy metal enrichment capabilities of the plant. Notably, some microorganisms (e.g., Burkholderia, Brevundimonas, Paraglomus, and Trichoderma) and enzymes (e.g., P-type ATPases, citrate synthase, catalase) of microorganisms were found to be potentially involved in facilitating the accumulation of Cd and Pb by E. sumatrensis. This research contributes to understanding how invasive alien plants can be utilized to remedy contaminated environments. It highlights the importance of modulating critical soil factors to enhance the phytoremediation potential of E. sumatrensis, which could aid in developing strategies to manage invasive plants and mitigate heavy metal pollution in ecosystems.

Assessment of growth, metal uptake efficiency and yield traits of castor bean genotypes for phytoremediation of lead contaminated soils of Chakera-Faisalabad having history of long term irrigation with waste water

The agricultural soil of Chakera village, Faisalabad, Pakistan is under significant threat due to irrigation with wastewater containing Pb. Castor bean (Ricinus communis L.), a non-edible oil seed crop showed considerable capacity for phytoremediation of heavy metals. Restoration of Pb contaminated soil of Chakera using castor bean until physiological maturity could be an effective approach for mitigating hazardous impacts of Pb contamination in the soil. Hence, the present study aimed to evaluate the growth, biochemical traits, phytoremediation potential, and yield attributes of two castor bean genotypes (NIAB-2020 and DS-30) under the conditions of two different soil-filled pots; uncontaminated soil of NIAB (0 mg Pb kg−1) and contaminated soil of Chakera (250 mg Pb kg−1). Results have shown that plant agronomic, biochemical and seed compositional analysis have revealed a faint drop on Chakera soil. Metal accumulation response resulted in highest shoot Pb uptake in DS-30 compared to NIAB-2020. Conversely, maximum Pb uptake in roots of NIAB-2020 (4470 µg plant−1) was recorded when compared with DS-30 (3576 µg plant−1). Highest translocation factor (TF) was calculated for DS-30, whereas, for the metal tolerance index (MTI), both genotypes exhibited non-significant difference. Interestingly, concentration of Pb in seeds remained undetected for both genotypes. The study indicates that NIAB-2020 exhibited slightly higher tolerance than DS-30, potentially leading to economic gains through widespread use of castor oil across industries, positioning castor bean as a promising candidate for rehabilitation of contaminated soils. Nevertheless, additional in-situ investigations are necessary to validate the findings of current pot study.

In situ bioaccumulation of metals by Prosopis juliflora and its detoxification potential at the metal contaminated sites

Heavy metals emanate from diverse anthropogenic activities and the top soil in the vicinity of these activities acts as an immediate sink and facilitates diffusion of heavy metals into the food chain. In the semi-arid plains of India, Prosopis juliflora is the most common and dominant weed along the motorways and barren lands including industrial environs. This investigation hypothesizes the adaptive nature of Prosopis juliflora in the metal enriched soils and attempts to understand its hyper-accumulating potential of metals besides bioconversion/detoxification capability. Prosopis juliflora samples (root, stem, leaves, and pods) from 100 sites in the environs of anthropogenic activities (vehicular emissions and industrial operations) were analyzed for heavy metal concentrations (Cu, Fe, Cr, Cd, Ni, Pb). Prosopis juliflora accumulate metals at the rate of 0.138 mg/kg/day DW for Copper (Cu), Fe: 0.142 mg/kg/day DW, Cr: 0.114 mg/kg/day DW, Ni: 0.048 mg/kg/day DW, Pb: 0.052 mg/kg/day DW, Cd: 0.009 mg/kg/day DW. Furthermore, X-ray Photoelectron Spectroscopy (XPS) metal oxidation state analysis revealed that in the pods of Prosopis juliflora heavy metals (Fe, Cr, Pb) largely existed in non-toxic form (toxic:non-toxic - 3:6), while in the under canopy soil, metals predominantly existed in toxic form (toxic:non-toxic - 7:2); conclusively XPS results ascertains the heavy metal bioconversion/detoxification potential of the plant. These findings suggest that presence of Prosopis juliflora coppice in the barren landscapes across the transportation corridors and metal based industrial zones may ideally favor phyto-remediation of heavy metals.

Sulfur availability and nodulation modify the response of Robinia pseudoacacia L. to lead (Pb) exposure

Both sulfur (S) supply and legume-rhizobium symbiosis can significantly contribute to enhancing the efficiency of phytoremediation of heavy metals (HMs). However, the regulatory mechanism determining the performance of legumes at lead (Pb) exposure have not been elucidated. Here, we cultivated black locust (Robinia pseudoacacia L.), a leguminous woody pioneer species at three S supply levels (i.e., deficient, moderate, and high S) with rhizobia inoculation and investigated the interaction of these treatments upon Pb exposure. Our results revealed that the root system of Robinia has a strong Pb accumulation and anti-oxidative capacity that protect the leaves from Pb toxicity. Compared with moderate S supply, high S supply significantly increased Pb accumulation in roots by promoting the synthesis of reduced S compounds (i.e., thiols, phytochelatin), and also strengthened the antioxidant system in leaves. Weakened defense at deficient S supply was indicated by enhanced oxidative damage. Rhizobia inoculation alleviated the oxidative damage of its Robinia host by immobilizing Pb to reduce its absorption by root cells. Together with enhanced Pb chelation in leaves, these mechanisms strengthen Pb detoxification in the Robinia-rhizobia symbiosis. Our results indicate that appropriate S supply can improve the defense of legume-rhizobia symbiosis against HM toxicity.

GLDA exhibits advantages in the phytoextraction of Cd and Ni in land-applied municipal sludge.

Landscape utilization is a green and environment-friendly way of disposing of compost sludge. Garden plants can extract heavy metals from the sludge of land use, but the effect is not enough to be widely used. Chelating agents have been found to facilitate the extraction of heavy metals from plants and are expected to be popularized if they are also environmentally friendly. In this study, the effects of methylglycinediacetic acid trisodium salt (MGDA), tetrasodium glutamate diacetate (GLDA), and ethylene diamine tetraacetate (EDTA) on the extraction of Ni and Cd from compost sludge by SymphytumofficinaleL. were studied through the pot experiment. Compared with the control group, the application of 5-10 mmol kg-1 MGDA and 1-9 mmol kg-1 GLDA promoted plant growth, while the application of 3-4 mmol kg-1 EDTA inhibited plant growth. The highest Ni content in shoots appeared in 4 mmol kg-1 GLDA treatment, which was 4.2 times that of the CK group. The highest shoot Cd concentration appeared in 4 mmol kg-1 EDTA treatment, 6.5 times that of CK. The promotion effects of the three reagents on the acid-extractable state of Cd were similar, while that of GLDA on the acid-extractable state of Ni was outstanding. The results of this study suggested that S. officinale could be a potential phytoextraction plant for Cd and Ni, and GLDA could friendly promote the Ni phytoextraction ability of the plant. The study provides a new and efficient method for phytoremediation of heavy metals in soil.

Biotechnological approaches for enhancement of heavy metal phytoremediation capacity of plants.

Heavy metals are extremely hazardous for human health due to their toxic effects. They are non-biodegradable in nature, thus remain in the environment and enter and accumulate in the human body through biomagnification; hence, there is a serious need of their remediation. Phytoremediation has emerged as a green, sustainable, and effective solution for heavy metal removal and many plant species could be employed for this purpose. Plants are able to sequester substantial quantity of heavy metals, in some cases thousands of ppm, due to their robust physiology enabling high metal tolerance and anatomy supporting metal ion accumulation. Identification and modification of potential target genes involved in heavy metal accumulation have led to improved phytoremediation capacity of plants at the molecular level. The introduction of foreign genes through genetic engineering approaches has further enhanced phytoremediation capacity manifolds. This review gives an insight towards improving the phytoremediation efficiency through a better understanding of molecular mechanisms involved, expression of different proteins, genetic engineering approaches for transgenic production, and genetic modifications. It also comprehends novel omics tools such as genomics, metabolomics, proteomics, transcriptomics, and genome editing technologies for improvement of phytoremediation ability of plants.

Assessing the Risk, Bioavailability, and Phytoremediation of Heavy Metals in Agricultural Soils: Implications for Crop Safety and Human Health

This review addresses heavy metal contamination in agricultural soils, focusing on bioavailability, toxicity, and phytoremediation techniques. We identify significant regional variations in cadmium and lead levels, posing health risks through crop consumption. Effective phytoremediation methods, such as phytoextraction and Phytostabilization, have shown marked improvements over recent years. Recommendations include best practices for soil management, stringent regulatory measures, and advanced research in biotechnological remediation methods. This study underscores the urgent need for integrated strategies to ensure food safety and sustainable agriculture in sector.

Root-soil-microbiome interaction in the rhizosphere of Masson pine (Pinus massoniana) under different levels of heavy metal pollution

Heavy metal pollution of the soil affects the environment and human health. Masson pine is a good candidate for phytoremediation of heavy metal in mining areas. Microorganisms in the rhizosphere can help with the accumulation of heavy metal in host plants. However, studies on its rhizosphere bacterial communities under heavy metal pollution are still limited. Therefore, in this study, the chemical and bacterial characteristics of Masson pine rhizosphere under four different levels of heavy metal pollution were investigated using 16 S rRNA gene sequencing, soil chemistry and analysis of plant enzyme activities. The results showed that soil heavy metal content, plant oxidative stress and microbial diversity damage were lower the farther they were from the mine dump. The co-occurrence network relationship of slightly polluted soils (C1 and C2) was more complicated than that of highly polluted soils (C3 and C4). Relative abundance analysis indicated Sphingomonas and Pseudolabrys were more abundant in slightly polluted soils (C1 and C2), while Gaiella and Haliangium were more abundant in highly polluted soils (C3 and C4). LEfSe analysis indicated Burkholderiaceae, Xanthobacteraceae, Gemmatimonadaceae, Gaiellaceae were significantly enriched in C1 to C4 site, respectively. Mantel analysis showed that available cadmium (Cd) contents of soil was the most important factor influencing the bacterial community assembly. Correlation analysis showed that eight bacterial genus were significantly positively associated with soil available Cd content. To the best of our knowledge, this is the first study to investigate the rhizospheric bacterial community of Masson pine trees under different degrees of heavy metal contamination, which lays the foundation for beneficial bacteria-based phytoremediation using Masson pines in the future.