Metal Stress Research Articles

New piperazine derivatives helvamides B–C from the marine-derived fungus Penicillium velutinum ZK-14 uncovered by OSMAC (One Strain Many Compounds) strategy

Four extracts of the marine-derived fungus Penicillium velutinum J.F.H. Beyma were obtained via metal ions stress conditions based on the OSMAC (One Strain Many Compounds) strategy. Using a combination of modern approaches such as LC/UV, LC/MS and bioactivity data analysis, as well as in silico calculations, influence metal stress factors to change metabolite profiles Penicillium velutinum were analyzed. From the ethyl acetate extract of the P. velutinum were isolated two new piperazine derivatives helvamides B (1) and C (2) together with known saroclazin A (3) (4S,5R,7S)-4,11-dihydroxy-guaia-1(2),9(10)-dien (4). Their structures were established based on spectroscopic methods. The absolute configuration of helvamide B (1) as 2R,5R was determined by a combination of the X-ray analysis and by time-dependent density functional theory (TD-DFT) calculations of electronic circular dichroism (ECD) spectra. The cytotoxic activity of the isolated compounds against human prostate cancer PC-3 and human embryonic kidney HEK-293 cells and growth inhibition activity against yeast-like fungi Candida albicans were assayed.Graphical

Genome-wide identification of chalcone synthase (CHS) family members and their expression patterns at the sprouting stage of common bean (Phaseolus vulgaris) under abiotic stress

Secondary metabolites such as flavonoids, produced by plants, could help plants cope with external stress. Flavonoid synthesis is catalyzed by chalcone synthase (CHS). CHS plays a broad role in the growth, development, and physiological activities of plants. However, studies of the CHS gene family in Phaseolus vulgaris are limited. In this study, the HMMER search tool was used to identify 29 CHS members in the reference genome of P. vulgaris. These PvCHS members were divided into 5 subgroups. Notably, subfamilies with close genetic relationships exhibited similarities in motifs and gene structures of PvCHSs. Additionally, analysis of the cis-element indicated the involvement of PvCHSs in response to abiotic stress. Furthermore, quantitative real-time PCR (qRT-PCR) analysis under various abiotic stress conditions revealed that the majority of PvCHSs were associated with the response to salt stress (NaCl), alkaline salt stress (NaHCO3), and heavy metal stress (CdCl2). Particularly, PvCHS01, PvCHS05, PvCHS14, and PvCHS25 were significantly up-regulated under alkaline salt stress. PvCHSs were also correlated with CHS activity and flavonoid content. In addition, exogenous flavonoids were observed to significantly decrease accumulation of ROS in P. vulgaris under alkaline salt stress. This study provides a basis for further analysis of the mechanisms underlying the response of PvCHSs to abiotic stress.

Overexpression of sweetpotato glutamylcysteine synthetase (IbGCS) in Arabidopsis confers tolerance to drought and salt stresses.

Various environmental stresses induce the production of reactive oxygen species (ROS), which have deleterious effects on plant cells. Glutathione (GSH) is an antioxidant used to counteract reactive oxygen species. Glutathione is produced by glutamylcysteine synthetase (GCS) and glutathione synthetase (GS). However, evidence for the GCS gene in sweetpotato remains scarce. In this study, the full-length cDNA sequence of IbGCS isolated from sweetpotato cultivar Xu18 was 1566bp in length, which encodes 521 amino acids. The qRT-PCR analysis revealed a significantly higher expression of the IbGCS in sweetpotato flowers, and the gene was induced by salinity, abscisic acid (ABA), drought, extreme temperature and heavy metal stresses. The seed germination rate, root elongation and fresh weight were promoted in T3 Arabidopsis IbGCS-overexpressing lines (OEs) in contrast to wild type (WT) plants under mannitol and salt stresses. In addition, the soil drought and salt stress experiment results indicated that IbGCS overexpression in Arabidopsis reduced the malondialdehyde (MDA) content, enhanced the levels of GCS activity, GSH and AsA content, and antioxidant enzyme activity. In summary, overexpressing IbGCS in Arabidopsis showed improved salt and drought tolerance.

Heavy Metal Stress in Medicinal Plants: Detoxification Mechanisms, Antioxidants, and Implications for Human Health

Heavy Metal Stress in Medicinal Plants: Detoxification Mechanisms, Antioxidants, and Implications for Human Health

Enhancing the biodiesel production in the green alga Chlorella vulgaris by heavy metal stress and prediction of fuel properties from fatty acid profiles.

The green microalga Chlorella vulgaris was used as a test organism during this study for evaluation of the impact of different heavy metal stress, Mn2+, Co2+, and Zn2+, on enhancing the biodiesel production. The algal cultures were grown for 13 days under heavy metal stress after which were subjected to estimation of growth, some primary metabolites, lipid, and fatty acid profiles. The maximum lipid accumulation (283.30 mg/g CDW) was recorded in the algal culture treated with 3µM cobalt nitrate. Application of 2 mM manganese chloride; 1, 2, and 3 μM cobalt nitrate; and 0.2, 0.4, and 0.6 mM zinc sulfate caused highly significant increases in the lipid contents amounting to 183.8, 191.4, 230.6, 283.3, 176.3, 226.0, and 212.1 mg/g CDW, respectively, in comparison to control (153.4 mg/g CDW). The maximum proportion of saturated fatty acids (SFA) (64.44%) was noted in the culture treated with 6 mM MnCl2 due to the existence of palmitic acid (C16:0), stearic acid (C18:0), and pentadecylic acid (C15:0) which are represented by 53.59%, 5.96%, and 1.37%, respectively, of the total FAs. Relative increase in energy compound (REEC) showed that 1, 2, and 3 µM Co2+ lead to the highest stimulation in lipid and carbohydrate contents to 0.207, 0.352, and 0.329×103%, respectively. Empirical formulas were used for the assessment of biodiesel fuel properties based on FAME composition. The estimated properties met the prescribed international standard criteria.

LCMS-Metabolomic Profiling and Genome Mining of Delftia lacustris DSM 21246 Revealed Lipophilic Delftibactin Metallophores.

Bacteria have evolved various strategies to combat heavy metal stress, including the secretion of small molecules, known as metallophores. These molecules hold a potential role in the mitigation of toxic metal contamination from the environment (bioremediation). Herein, we employed combined comparative metabolomic and genomic analyses to study the metallophores excreted by Delftia lacustris DSM 21246. LCMS-metabolomic analysis of this bacterium cultured under iron limitation led to a suite of lipophilic metallophores exclusively secreted in response to iron starvation. Additionally, we conducted genome sequencing of the DSM 21246 strain using nanopore sequencing technology and employed antiSMASH to mine the genome, leading to the identification of a biosynthetic gene cluster (BGC) matching the known BGC responsible for delftibactin A production. The isolated suite of amphiphilic metallophores, termed delftibactins C-F (1-4), was characterized using various chromatographic, spectroscopic, and bioinformatic techniques. The planar structure of these compounds was elucidated through 1D and 2D NMR analyses, as well as LCMS/MS-based fragmentation studies. Notably, their structures differed from previously known delftibactins due to the presence of a lipid tail. Marfey's and bioinformatic analyses were employed to determine the absolute configuration of the peptide scaffold. Delftibactin A, a previously identified metallophore, has exhibited a gold biomineralizing property; compound 1 was tested for and also demonstrated this property.

Heavy metal stress in the agro-environment: consequences, adaptations and remediation

Heavy metal stress in the agro-environment: consequences, adaptations and remediation

Climate Crisis and Agricultural Response: Climate Resilient Crops for Sustainability in Food Production Systems

Climate change encompasses altered levels of temperature and humidity, variability in the rainfall pattern, fluctuations in weather parameters, rise in ambient CO2 levels, emission of greenhouse gases, global warming, etc. that results in extreme events and disasters as cyclones, floods, droughts, salinity, nutrient and heavy metal stress, change in arthropod diversity and emergence of new invasive pests. This results in un-usual effects in agro-ecosystems leading to changes in cropping patterns, crop diversity, and their interaction with biotic and abiotic stress factors, threatening livelihood, food, and nutritional security. Population displacement, declining food productivity, and vulnerable agro-ecosystems are the major consequences of altered meteorological events that occur due to climate change. Therefore, substitution of traditional crops with crops that exhibit resilience to climate crisis is the need of the hour. Smart breeding approaches and precision farming technologies as remote sensing and spectral analysis, artificial intelligence, machine learning, speed breeding, genome analysis, genetic manipulation, gene drive systems, system biology study, omics approaches, etc can make agricultural production climate resilient and sustainable. Response of biofortified crops under changing climate must also be assessed to improve the crop productivity and output.

Response mechanism of Pteris vittata L. under long-term combined heavy metal stress based on transcriptome analysis

ABSTRACT The response mechanism of plants under long-term heavy metal stress is not fully understood. This study compared and analyzed Pteris vittata L. of the mining areas, which significantly enriched multiple heavy metals (As, Cd, Hg, Pb, Zn, Cu, Sn, Sb, Cr), with those in non mining areas. The transcriptome analysis results showed that compared with non mining areas, there were 1226 genes upregulated and 1801 genes downregulated in the mining area. Functional enrichment analysis of these differentially expressed genes indicates that under long-term heavy metal stress, gene expression in related biological pathways such as Pteris vittata L. phenylpropanoid biosynthesis, starch and sucrose metabolism is inhibited. However, Pteris vittata L. also enhances its resistance to stress by upregulating the expression of genes related to these pathways, such as HCT and POD, enabling it to adapt to heavy metal pollution environments.

Biochar for the Mitigation of Metal/Metalloid Stress in Plants

AbstractMetal(loid) pollution has become one of the most pressing environmental issues, threatening all living organisms. Metal(loid) stress adversely impacts plant growth, physiology, and overall productivity. Numerous physicochemical approaches have been developed and employed to counteract and reduce the detrimental effects of metal(loid)s. However, these methods have raised environmental concerns, leading to questions about their appropriateness and efficacy. Consequently, alternative and eco-friendly solutions, such as the application of biochar, have gained prominence. Biochar is a carbon-rich material derived from the pyrolysis and hydrothermal processes of various organic materials. Due to its exceptional physicochemical properties, biochar is believed to enhance soil quality and fertility. Several global studies have underscored the positive role of biochar in reducing the uptake of metal(loid)s by plants in polluted soils. In this article, we explore various facets of plant reactions to metal(loid)s toxicity and attempt to draw links between biochar use and improvements in plant physiology and performance. We also review the effectiveness of biochar in phytoremediation, its influence on nutrient adsorption mechanisms, and its role in assisting plant growth and defense systems.

An activatable fluorescence probe for rapid detection and in situ imaging of β-galactosidase activity in cabbage roots under heavy metal stress

β-Galactosidase (β-gal), an enzyme related to cell wall degradation, plays an important role in regulating cell wall metabolism and reconstruction. However, activatable fluorescence probes for the detection and imaging of β-gal fluctuations in plants have been less exploited. Herein, we report an activatable fluorescent probe based on intramolecular charge transfer (ICT), benzothiazole coumarin-bearing β-galactoside (BC-βgal), to achieve distinct in situ imaging of β-gal in plant cells. It exhibits high sensitivity and selectivity to β-gal with a fast response (8 min). BC-βgal can be used to efficiently detect the alternations of intracellular β-gal levels in cabbage root cells with considerable imaging integrity and imaging contrast. Significantly, BC-βgal can assess β-gal activity in cabbage roots under heavy metal stress (Cd2+, Cu2+, and Pb2+), revealing that β-gal activity is negatively correlated with the severity of heavy metal stress. Our work thus facilitates the study of β-gal biological mechanisms.

Pervasive influence of heavy metals on metabolic pathways is potentially relieved by hesperidin to enhance the phytoremediation efficiency of Bassia scoparia.

Hesperidin (HSP), a flavonoid, is a potent antioxidant, metal chelator, mediator of signaling pathways, and regulator of metal uptake in plants. The study examined the ameliorative effects of HSP (100 μM) on Bassia scoparia grown under excessive levels of heavy metals (zinc (500 mg kg-1), copper (400 mg kg-1), cadmium (100 mg kg-1), and chromium (100 mg kg-1)). The study clarifies the underlying mechanisms by which HSP lessens metabolic mayhem to enhance metal stress tolerance and phytoremediation efficiency of Bassia scoparia. Plants manifested diminished growth because of a drop in chlorophyll content and nutrient acquisition, along with exacerbated deterioration of cellular membranes reflected in elevated reactive oxygen species (ROS) production, lipid peroxidation, and relative membrane permeability. Besides the colossal production of cytotoxic methylglyoxal, the activity of lipoxygenase was also higher in plants under metal toxicity. Conversely, hesperidin suppressed the production of cytotoxic ROS and methylglyoxal. Hesperidin improved oxidative defense that protected membrane integrity. Hesperidin caused a more significant accumulation of osmolytes, non-protein thiols, and phytochelatins, thereby rendering metal ions non-toxic. Hydrogen sulfide and nitric oxide endogenous levels were intricately maintained higher in plants treated with HSP. Hesperidin increased metal accumulation in Bassia scoparia and thereby had the potential to promote the reclamation of metal-contaminated soils.

Transcriptomic and metabolomic insights into the antimony stress response of tall fescue (Festuca arundinacea)

Antimony (Sb) is a toxic heavy metal that severely inhibits plant growth and development and threatens human health. Tall fescue, one of the most widely used grasses, has been reported to tolerate heavy metal stress. However, the adaptive mechanisms of Sb stress in tall fescue remain largely unknown. In this study, transcriptomic and metabolomic techniques were applied to elucidate the molecular mechanism of the Sb stress response in tall fescue. These results showed that the defense process in tall fescue was rapidly triggered during the early stages of Sb stress. Sb stress had toxic effects on tall fescue, and the cell wall and voltage-gated channels are crucial for regulating Sb permeation into the cells. In addition, the pathway of glycine, serine and threonine metabolism may play key roles in the Sb stress response of tall fescue. Genes such as ALDH7A1 and AGXT2 and metabolites such as aspartic acid, pyruvic acid, and biuret, which are related to biological processes and pathways, were key genes and compounds in the Sb stress response of tall fescue. Therefore, the regulatory mechanisms of specific genes and pathways should be investigated further to improve Sb stress tolerance.

Heavy Metal Stress Management through Phytoremediation to Mitigate Climate Change Impacts: An Overview

Plant stresses are the conditions that adversely affect the growth, development, or productivity of plants/trees and can be caused by various physical, chemical, and biological factors. However, stress caused by the influence of heavy metals has a notable adverse effect on plant growth and productivity. These heavy metal contaminations are responsible for the harmful effects on biotic (plants and associated organisms) and the abiotic (soil, water, and air) environment. If not properly managed, mining activities are considered to be the prime source of heavy metal contamination in the surrounding environment. Phytoremediation may effectively remediate a wide range of heavy metal contaminants in different environments and hence offers an effective, carbon-neutral, and ecologically beneficial method for the removal of hazardous heavy metal contaminants. Phytoremediation enhances the growth and development of plants and nourishes the environment resulting in the ill effects of climate extremes in disturbed areas and hence mitigating the impacts of climate change. Phytoremediation has been widely studied for the remediation of heavy metal stress but it hasn't yet achieved commercial viability in degraded ecosystems of India where it is required the most. Through this review article, we tried to minimize this gap by reviewing some important phytoremediation studies in India which successfully reduced the negative impacts of heavy metals in different degraded ecosystems.

Bioremediation of heavy metals-contaminated sites by microbial extracellular polymeric substances – A critical view

Heavy metal contamination in the atmosphere poses substantial threats to ecosystems. Traditional methods for the removal of HM-contaminated sites, such as physical and chemical treatments, often have limitations in terms of efficiency, cost, and potential negative impacts on the environment. As a result, there is growing interest in exploring alternative and sustainable approaches, such as bioremediation. Bioremediation is a promising technology that utilizes the inherent abilities of microorganisms to degrade or transform pollutants into less harmful forms. Microbial exopolysaccharides have gained attention as potential tools in bioremediation strategies due to their unique physicochemical properties and their ability to interact with heavy metals. This work aims to provide an overview of the role of microbial extracellular polymeric substances (EPS) in the bioremediation of HM-contaminated sites. First, the mechanisms by which EPS facilitates heavy metal sequestration are discussed. EPS can form metal-complexing agents, such as chelators and ion-binding sites, which enhance the immobilization and precipitation of heavy metals, reducing their bioavailability and toxicity. EPS can act as a protective barrier, shielding microorganisms from heavy metal stress and facilitating their survival and growth. Additionally, EPS production can be induced or enhanced in response to heavy metal exposure, potentially increasing the efficiency of bioremediation processes.

Exploring the potential of Aspergillus terreus 2021, WLL-ISO: A dual-functional agent for heavy metal removal and self-aggregation in wastewater treatment

This study investigates the potential of Aspergillus terreus strain 2021, WLL-ISO, isolated from Cu2+-rich wastewater, for heavy metal removal and spheroidization. Phylogenetic analysis, supported by biochemical characterization, reveals its close affiliation with A. terreus. The fungus exhibits robust growth and diverse substrate utilization. Notably, it achieves complete removal of Cu2+ from solutions (initial concentrations: 10–50 mg/L) alongside self-spheroidization. The resulting pellets display enhanced settleability and a porous structure conducive to heavy metal adsorption. Langmuir and Freundlich models confirm the fungus’s high affinity and capacity for heavy metal adsorption, particularly Cu2+, Zn2+, Pb2+, and Fe2+. EPS analysis reveals significant compositional alterations under heavy metal stress, impacting pellet formation. Three-dimensional excitation-emission matrix spectrum analysis detects activation of humic acid-like organics in response to Cu2+ stress. Moreover, the fungus exhibits promising Cu2+ removal from real wastewater, highlighting its practical potential in heavy metal remediation. The self-aggregating nature of the fungus presents opportunities for the recycling of adsorbents post-heavy metal adsorption, enhancing the sustainability of the remediation process.

Oceanobacillus picturae alleviates cadmium stress and promotes growth in soybean seedlings

Cadmium (Cd) is a heavy metal that significantly impacts human health and the environment. Microorganisms play a crucial role in reducing heavy metal stress in plants; however, the mechanisms by which microorganisms enhance plant tolerance to Cd stress and the interplay between plants and microorganisms under such stress remain unclear. In this study, Oceanobacillus picturae (O. picturae) was isolated for interaction with soybean seedlings under Cd stress. Results indicated that Cd treatment alone markedly inhibited soybean seedling growth. Conversely, inoculation with O. picturae significantly improved growth indices such as plant height, root length, and fresh weight, while also promoting recovery in soil physiological indicators and pH. Metabolomic and transcriptomic analyses identified 157 genes related to aspartic acid, cysteine, and flavonoid biosynthesis pathways. Sixty-three microbial species were significantly associated with metabolites in these pathways, including pathogenic, adversity-resistant, and bioconductive bacteria. This research experimentally demonstrates, for the first time, the growth-promoting effect of the O. picturae strain on soybean seedlings under non-stress conditions. It also highlights its role in enhancing root growth and reducing Cd accumulation in the roots under Cd stress. Additionally, through the utilization of untargeted metabolomics, metagenomics, and transcriptomics for a multi-omics analysis, we investigated the impact of O. picturae on the soil microbiome and its correlation with differential gene expression in plants. This innovative approach unveils the molecular mechanisms underlying O. picturae's promotion of root growth and adaptation to Cd stress.

CRISPR-mediated BnaNRAMP1 homologous copies editing create a low Cd-accumulation oilseed rape germplasm with unaffected yield

Brassica napus, one of the most important oil crops cultivated globally, is severely impacted by prolonged soil contamination with cadmium (Cd), resulting in decreased yields and poor seed quality. This crop exhibits a high adsorption capacity for Cd, thereby making the creation of seed resources with low Cd-accumulation as an essential strategy to alleviate this challenge. To address this issue, we genetically edited BnaNRAMP1 in B. napus by targeting three different exon regions, resulting in new germplasm resources with significant differences in Cd accumulation capacity and unaffected yield. Among these, the mutant K140-22, specifically targeting the seventh exon, is distinguished by its substantially reduced Cd accumulation. Further, enzyme assays of the antioxidant defense system in both roots and shoots of K140-22 revealed its enhanced antioxidant activity, which contributes to elucidate the molecular mechanisms of plant tolerance to heavy metal stress. Remarkably, this mutant also maintained equivalent agronomic traits and seed quality, which highlights its potential as a germplasm resource for rapeseed breeding for low Cd accumulation, as well as for elevating rapeseed economic value in Cd contaminated soil.

The roles of rare and abundant microbial species in the primary succession of biological soil crusts are differentiated in metal tailings ponds with different states

Tailings ponds formed by long-term accumulation of mineral processing waste have become a global environmental problem. Even worse, tailings ponds are often simply abandoned or landfilled after they cease to be used. This allows pollution to persist and continue to spread in the environment. The significance of primary succession mediated by biological soil crusts for tailings pond remediation has been illustrated by previous studies. However, the process of primary succession may not be the same at different stages during the lifetime of tailings ponds. Therefore, we investigated the environmental differences and the successional characteristics of microbial communities in the primary successional stage of tailings ponds at three different states. The results showed that the primary succession process positively changed the environment of tailings ponds in any state of tailings ponds. The primary successional stage determined the environmental quality more than the state of the tailings pond. In the recently abandoned tailings ponds, abundant species were more subjected to heavy metal stress, while rare species were mainly limited by nutrient content. We found that as the succession progressed, rare species gradually acquired their own community space and became more responsive to environmental stresses. Rare species played an important role in microbial keystone species groups.

The effect of heavy metals (Cd, Cu, and Pb) on plant growth parameters and the phytoremediation capacity of corn

Heavy metal contamination is currently a major global environmental issue. Heavy metals contaminate the soils where crops and vegetables grow. Maize (Zea mays L.) is widely employed for phytoremediation because of its high biomass output and metal accumulation capacity. Depending on the plant and soil properties, some metals can be dangerous in high amounts. During our in vitro experiment, different levels of Cd, Cu, and Pb were introduced to a growth medium to allow maize plants to develop under diverse conditions. The study examined numerous growth features under certain metal stress conditions, including seed germination, plant height, biomass, and chlorophyll content, as well as the toxicity symptoms and mechanisms of the most common heavy metals. The study revealed that, while the maize plant is a good heavy metal accumulator, high heavy metal concentrations had a negative impact on several growth indicators: at 250 ppm, Cd inhibited captive seed germination by 50% and wild seed germination by 42.9%; Pb suppressed captive seed germination by 57% and wild seed germination by 42.9%; and Cu inhibited germination in both seed types by 40%. Similarly, plant height decreased in the following order: Pb (36.2%), Cd (24.8%), and Cu (9.7%) for the captive seed plant, and Pb (46.7%), Cd (28%), and Cu (13%) for the wild seed plant. Keywords: MAIZE, STRESS, TOXICITY, HEAVY METAL, POLLUTION, PHYTOREMEDIATION, BIOACCUMULATION