Search Results (300)

Cadmium (Cd), a highly mobile and phytotoxic heavy metal, threatens plant growth and food safety and has increased interest in woody plant-based phytoremediation. However, the genome-wide characteristics of the NAC transcription factor family and its role in Cd tolerance remain largely unknown in pomegranate (Punica granatum L.), a stress-tolerant woody plant. In this study, 121 PgNAC genes were identified from the chromosome-level genome of the pomegranate cultivar ‘Tunisia’. Phylogenetic analysis classified these genes into two major groups and 16 subgroups. PgNAC genes were unevenly distributed across the eight chromosomes and showed evident clustered distribution patterns. Synteny and Ka/Ks analyses further revealed that segmental and tandem duplication jointly shaped the expansion of the PgNAC family, while the duplicated pairs have largely evolved under strong purifying selection. Conserved motif and gene structure analyses showed that PgNAC proteins possessed a highly conserved N-terminal NAM domain, whereas their C-terminal regions were relatively divergent. Promoter analysis further identified abundant hormone- and stress-responsive cis-elements, suggesting diverse regulatory roles of the PgNAC family. Transcriptome profiling identified PgNAC87, a member of the NAP subfamily, as a Cd-responsive candidate gene that was consistently upregulated in both roots and leaves under Cd stress. Heterologous overexpression of PgNAC87 in tobacco significantly enhanced Cd tolerance, as reflected by alleviated growth inhibition, increased antioxidant enzyme activities and osmotic adjustment substances, and reduced oxidative damage. Collectively, our results clarify the evolutionary features of the PgNAC family and its involvement in Cd-induced transcriptional regulation, while highlighting PgNAC87 as a potential genetic target for enhancing Cd tolerance in pomegranate and related woody species. Full article

Chromium (Cr) is one of the most toxic heavy metals in the environment. The tolerance to metal stress involves sophisticated regulation of gene expression networks, which involve microRNAs (miRNAs). However, the role of miRNAs in Cr stress response in Avicennia marina has not been resolved, and was addressed here. The analysis of response characteristics revealed that morpho-physiological traits such as root length, Cr accumulation level and antioxidant enzyme activity all exhibit significant changes under Cr stress. Via sRNA sequencing, a total of 27 known and 149 novel miRNAs were identified, 63 of which showed differential expression after Cr stress (q-value < 0.001). Further, 571 miRNA-target interaction pairs were identified for differentially expressed miRNAs, corresponding to 355 target genes. GO and KEGG analyses indicated that these target genes could participate in stress-related biological processes such as signal transduction, transcription regulation, protein synthesis and the MAPK signaling pathway. 54 miRNA target genes, corresponding to 37 miRNAs such as Ama-miR160, Ama-nmiR25-5p and Ama-nmiR118-5p, were enriched for “plant signal hormone transduction” (ko04075), “phenylpropanoid biosynthesis” (ko00940) and “MAPK signaling pathway” (ko04016), which indicated an important role of these miRNAs in regulating Cr stress response in A. marina. Based on the findings, a Cr stress-responsive regulatory model was developed, offering new insights into the molecular regulatory mechanisms of Cr response. In conclusion, this study shows the identity and potential role of miRNAs in the heavy metal stress response of A. marina, and provides the foundation for future research. Full article

Background: Metallic and metal oxide nanoparticles are increasingly explored as antimicrobial biomaterials in endodontics due to their multi-target mechanisms of action, largely mediated by metal ion release (e.g., Ag⁺, Cu⁺). However, bacterial metal resistance systems, particularly efflux-related proteins, may influence their antimicrobial performance. This study aimed to analyze the prevalence and distribution of metal resistance-associated proteins in bacteria involved in endodontic infections using a bioinformatic approach. Methods: An in silico, cross-sectional bioinformatic analysis was conducted using publicly available genomes from the Bacterial and Viral Bioinformatics Resource Center (BV-BRC). Bacterial species associated with acute apical abscess (AAA), symptomatic apical periodontitis (SAP), asymptomatic apical periodontitis (AAP), and post-treatment apical periodontitis (PTAP) were included. The presence of selected metal resistance-related proteins (CutC, CopA, CzcA, CusA, SilA, P-type ATPase, and PA3920) was assessed using a binary presence/absence framework. Prevalence, group comparisons (Fisher’s exact test), and co-occurrence patterns (Phi coefficient) were analyzed. Results: Metal resistance-associated proteins were widely distributed across all infection types, with prevalence ranging from 70.0% to 82.9% and no significant differences between groups (p > 0.05). CutC was the most prevalent protein, followed by CopA and CzcA, whereas SilA and PA3920 were not detected. Correlation analysis revealed consistent co-occurrence patterns among key taxa, including Porphyromonas gingivalis, Fusobacterium nucleatum, and Prevotella spp. Conclusions: Metal resistance-related proteins are broadly distributed in endodontic microbiota, indicating a conserved genetic capacity for metal tolerance. These findings suggest that microbial resistance determinants may influence, but do not directly determine, the antimicrobial performance of nanoparticle-based biomaterials. This study provides a hypothesis-generating, bioinformatic framework to support the design and optimization of antimicrobial biomaterials, highlighting the need for experimental validation and integration of phenotypic and biofilm-based analyses. Full article

Cotton (Gossypium hirsutum L.) is a promising candidate for an Arsenic (As)-tolerant plant due to its low As accumulation in fibers. The individual arbuscular mycorrhizal fungi (AMF) inoculation or exogenous calcium (Ca²⁺) application is known to enhance heavy metal tolerance in higher plants; however, their synergistic mechanisms in alleviating As stress in cotton remain poorly understood. A three-factor pot experiment was conducted, including two levels of AMF (Funneliformis mosseae C.Walker & A.Schüßler) inoculation (non-inoculated/inoculated), As stress (0/100 mgAs⁵⁺·kg⁻¹soil), and exogenous Ca²⁺ (CaCl₂) application (0/20 mmol·L⁻¹ CaCl₂). AMF inoculation and Ca²⁺ application were investigated for their effects on cotton growth, root morphology, photosynthetic characteristics, osmotic regulators, antioxidant enzyme activities, and ion homeostasis under As stress. Results showed As stress significantly disrupted cotton growth (decreased plant height, shoot and root dry weight) and root morphology (reduced total root length, root area, and root fork number), photosynthetic capacity (reduced Pn, Ci, Fv/Fm, and ΦPSII), osmotic adjustment (decreased proline, soluble sugar and protein), antioxidant defense (inhibited SOD, POD, CAT activities), and K⁺/Ca²⁺ homeostasis (reduced concentration of K⁺ and Ca²⁺, and K⁺/Ca²⁺ ratio). Both AMF inoculation and Ca²⁺ application independently alleviated these adverse effects of As stress. At the same time, AMF symbiosis combined with exogenous Ca²⁺ was better than AMF inoculation or Ca²⁺ application alone in optimizing root architecture, improving stomatal function and photosynthetic efficiency, enhancing osmotic regulator accumulation and antioxidant enzyme activities, and restoring ion balance under As stress. Three-way ANOVA confirmed significant As×AMF×Ca²⁺ interactions on key parameters such as Pn and ΦPSII. In summary, both AMF inoculation and Ca²⁺ application synergistically enhanced cotton As tolerance through regulating growth, root morphology, photosynthetic characteristics, osmotic regulators, antioxidant enzyme activities, and ion homeostasis, demonstrating its potential for sustainable cotton cultivation in As-contaminated soils. Full article

Metal homeostasis, which coordinates the influx and efflux of essential elements such as iron (Fe) and manganese (Mn) in chloroplasts, is essential for optimum photosynthesis, especially in metal-accumulating plants. Brassica juncea (Indian mustard) is a metal-tolerant species with a strong metal accumulation capacity, making it a suitable model for studying transition metal homeostasis. In this study, we identified two efflux transporters, BjYSL6.1 and BjYSL6.4, that localize in the endomembrane system of Schizosaccharomyces pombe and interact with the chloroplast Mn influx transporter BjNRAMP4.1 at the plasma membrane and within the chloroplasts. Bimolecular fluorescence complementation and split-ubiquitin yeast two-hybrid assays confirmed specific protein–protein interactions among these transporters, as well as with the membrane-bound thioredoxin BjHCF164, a known regulator of photosynthetic electron transport. Gene expression studies revealed that BjNRAMP4.1 and BjYSL6 isoforms are inversely regulated under Fe and Mn stress conditions, with BjNRAMP4.1 being strongly induced under deficiency, whereas BjYSL6.1 and BjYSL6.4 are downregulated. These findings suggest that a coordinated network involving BjNRAMP4.1, BjYSL6s, and BjHCF164 modulates metal influx and efflux at the chloroplast and plasma membrane interfaces, thereby maintaining metal homeostasis, which is critical for photosynthetic efficiency in B. juncea. Full article

The toxicity of copper (Cu) severely affects the growth and physiological metabolism of plants. 2-(3,4-Dichlorophenoxy) triethylamine (DCPTA) is a plant growth regulator known to enhance plant tolerance to various abiotic stresses; however, its specific role in mitigating Cu toxicity via cell wall modulation and nitrogen metabolism remains unclear. “Zhongnong 26” (Cucumis sativus L.) seedlings were subjected to a randomized block design with four treatments: control (CK), 0.25 mg/L DCPTA, 50 μM Cu, and 50 μM Cu + 0.25 mg/L DCPTA, with three biological replicates per treatment. The results indicated that DCPTA application significantly alleviated Cu-induced growth inhibition. Specifically, DCPTA improved root system architecture by markedly increasing total root length (68.8%), surface area (68.7%), and the number and length of secondary lateral roots (69.6%, 173.2%). Furthermore, DCPTA enhanced the biosynthesis of cell wall polysaccharides—including pectin (24.3%), hemicellulose 1 (22.4%), hemicellulose 2 (23.7%) and cellulose (33.1%) in roots. Fourier Transform Infrared (FTIR) spectroscopy analysis revealed that DCPTA modified functional groups (e.g., –OH, –COOH) within the cell wall, enhancing their metal-chelating capacity. Consequently, DCPTA promoted the immobilization of Cu in the root cell wall fractions (particularly pectin and HC2) and shifted Cu into less toxic, pectate- and protein-bound forms, thereby reducing its translocation to leaves. Additionally, DCPTA restored the activities of key nitrogen metabolism enzymes in leaves and roots. Compared with Cu treatment alone, nitrate reductase (NR) activity increased by 77.7% and 90.6%, while glutamine synthetase (GS) activity remained stable, and glutamate synthase (GOGAT) activity increased by 10.3% and 71.3% in leaves and roots, respectively. In conclusion, DCPTA enhances copper sequestration in roots by coordinating the regulation of root structure and cell wall strengthening (with an increase in pectin and hemicellulose content). This is crucial for protecting the nitrogen metabolism within the cells (including the enzymes that drive the nitrate–ammonium reduction pathway) to maintain metabolic balance under Cu stress. Full article

Arsenic-contaminated groundwater is a major environmental concern, particularly in northern Argentina. Here, Microbacterium oxydans AE038-20, isolated from arsenic-rich groundwater, was investigated to elucidate its tolerance and transformation capacity. Growth assays showed that the strain tolerates inorganic arsenic [As(III), As(V)] and methylarsenite [MAs(III)] without significant inhibition. Speciation analyses revealed progressive oxidation of As(III) to As(V), reaching near-complete conversion after 10 days. Similarly, MAs(III) was fully oxidized to MAs(V). Genome sequencing identified ars-related determinants, including arsR, arsC, putative arsenite efflux systems, and arsP, supporting detoxification via arsenate reduction and arsenite efflux. Proteomic analyses confirmed the expression of proteins related to arsenic resistance, oxidative stress response, and metal transport. However, no canonical arsenite oxidases were detected at either the genomic or proteomic level. Despite this, M. oxydans AE038-20 exhibited clear arsenic oxidation activity. The detection of pigment-associated proteins and in vitro oxidation assays suggest an alternative mechanism potentially mediated by redox-active pigments. These findings highlight an alternative pathway for arsenic transformation in environmental bacteria. Full article

Nickel (Ni) contamination threatens plant growth and ecosystem stability, and plant-growth-promoting rhizobacteria (PGPR) are sustainable bioremediation candidates. Here, we isolated and characterized a Ni-resistant PGPR strain, Microbacterium algeriense C14, from the rhizosphere of Zinnia elegans in Ni-contaminated soil. C14 exhibited exceptional Ni tolerance (up to 800 mg·L⁻¹), produced indole-3-acetic acid (IAA), and maintained pH homeostasis (8.3–8.7). XPS and XRD analyses confirmed a novel carboxylate-based precipitation mechanism: C14 secretes carboxyl-containing metabolites that coordinate with Ni²⁺ to form stable amorphous nickel–carboxylate complexes. Under Ni stress (50–600 mg·L⁻¹ for germination; 50–600 mg·kg⁻¹ soil for pot experiments), C14 inoculation increased the seed germination index by up to 47.3%, seedling root length by 36.9%, and mature plant aboveground fresh weight by 21.32%, while reducing plant Ni uptake by 38.7% (seedlings) and 49.9% (mature shoots). It also enhanced plant antioxidant-enzyme (SOD and POD) activities and soluble protein content, improved soil quality (pH +0.16–0.33 units, urease/acid phosphatase activities elevated), and reduced soil-available Ni by 23.7%. Additionally, C14 enriched Proteobacteria in the rhizosphere and modified microbial community structure. These results highlight M. algeriense C14 as a promising resource for Ni-contaminated soil remediation via integrated metal immobilization, growth promotion, and rhizosphere regulation. Full article

The Fruit Weight 2.2-like (FWL) gene family, characterized by the conserved PLAC8 domain, plays important roles in plant organ development and metal ion homeostasis. However, the systematic characterization of FWL genes in rice (Oryza sativa) and their involvement in abiotic stress responses remain insufficiently understood. In this study, a genome-wide identification of the FWL gene family in rice was performed, resulting in the identification of nine OsFWL genes, including a previously unreported member, OsFWL9. Phylogenetic analysis of FWL proteins from rice, maize, soybean, and Arabidopsis thaliana classified the family into three distinct subgroups, indicating both conserved and divergent evolutionary relationships. Structural and conserved motif analyses revealed that OsFWL proteins share similar domain architectures, while promoter analysis uncovered abundant cis-acting elements associated with stress responses, phytohormone signaling, and plant growth and development. Expression profiling demonstrated that most OsFWL genes were rapidly induced by drought, high temperature, salt, and arsenic stresses at the seedling stage, suggesting their broad involvement in abiotic stress adaptation. Notably, OsFWL8 exhibited a unique expression pattern, being significantly suppressed under arsenic stress. Functional characterization using CRISPR/Cas9-generated knockout mutants and overexpression lines revealed that OsFWL8 negatively regulates arsenic tolerance in rice. Overexpression of OsFWL8 markedly increased plant sensitivity to arsenic stress. Furthermore, arsenic detoxification-related genes, including OsABCC1 and OsPCS2, were significantly upregulated in fwl8 mutants under arsenic treatment. These results indicate that OsFWL8 may modulate arsenic tolerance by influencing arsenic sequestration and detoxification pathways. Overall, this study provides a comprehensive overview of the FWL gene family in rice and identifies OsFWL8 as a key regulator of arsenic stress response, offering valuable insights for improving rice tolerance to heavy metal stress. Full article

Imine reductases (IREDs) have emerged as valuable biocatalysts for the asymmetric synthesis of chiral amines, key intermediates in numerous active pharmaceutical ingredients. Their ability to operate under mild reaction conditions with high chemo- and stereoselectivity provides an attractive alternative to conventional metal-catalyzed or chemical reduction processes. However, the broader industrial application of wild-type IREDs is often constrained by their limited substrate scope and moderate catalytic efficiency. Recent advances in biocatalysis have demonstrated that engineered IREDs can catalyze the reduction of a wide range of natural and non-natural imines, significantly expanding their applicability in pharmaceutical and fine chemical synthesis. In parallel, enzyme immobilization strategies have proven highly effective for improving operational stability, facilitating enzyme reuse, and enabling continuous flow biocatalytic processes. Efficient cofactor regeneration systems have further enhanced the practical implementation of IRED-based transformations. Advances in protein engineering, including structure-guided design, semi-rational mutagenesis, and directed evolution, have generated enzyme variants with improved catalytic activity, stereoselectivity, and substrate tolerance. The integration of high-throughput screening technologies and machine-learning-assisted enzyme design has further accelerated the discovery and optimization of efficient IRED biocatalysts. This review summarizes recent progress in the protein engineering and immobilization of IREDs and discusses future perspectives for their industrial application. Full article

Cadmium (Cd) contamination in agricultural soils, especially in regions with a naturally high geochemical background such as Southwest China, poses a serious threat to food safety and the health of terrestrial ecosystems. Although arbuscular mycorrhizal fungi (AMFs) are known to enhance plant tolerance to heavy metals, the specific mechanisms by which dominant AMF species in karst soils—such as Funneliformis mosseae (Fm) and Rhizophagus intraradices (Ri)—immobilize Cd are not yet fully understood. In this study, a pot experiment with pepper plants was conducted to investigate the effects of Fm and Ri inoculation on Cd geochemistry in both the rhizosphere and bulk soil. Key results showed that AMF inoculation, especially with Fm, significantly reduced total Cd (by up to 33.8%) and bioavailable Cd (by up to 36.3%) concentrations in the soil, with a more pronounced effect within the rhizosphere. Accordingly, Cd content in pepper shoots was reduced by up to 15.0%. Inoculation also increased soil pH, organic matter, available phosphorus, and glomalin-related soil protein (GRSP) content. Redundancy analysis identified soil pH and total extractable GRSP as primary factors negatively correlated with Cd bioavailability. The study concludes that AMFs, particularly Fm, represent a potent bioremediation strategy by effectively immobilizing Cd in contaminated soils through mechanisms linked to GRSP production and pH elevation, thereby reducing its phytoavailability and translocation to edible plant parts. Full article

Cadmium (Cd) contamination severely threatens crop productivity and food safety, particularly in maize (Zea mays L.), which exhibits relatively high capacities for metal uptake and translocation. Metal tolerance proteins (MTPs) play essential roles in metal homeostasis and detoxification; however, the functions of maize MTP under Cd stress remain poorly understood. In this study, a comprehensive expression analysis of the maize MTP gene family revealed that two Zn-CDF members, ZmMTP1-1 and ZmMTP1-2, displayed the strongest and most consistent transcriptional induction in response to Cd stress, especially in roots. Phylogenetic and structural analyses confirmed that both genes are closely related to MTP1 homologs from other plant species, while exhibiting distinct gene structures and regulatory features. Functional characterization in transgenic Arabidopsis thaliana demonstrated that overexpression of ZmMTP1-1 or ZmMTP1-2 significantly enhanced tolerance to Cd and Zn stress, as reflected by improved seed germination, root growth, survival, and biomass accumulation. Enhanced metal tolerance was associated with elevated antioxidant enzyme activities, reduced oxidative damage, and coordinated upregulation of endogenous metal transporter genes. Moreover, heterologous expression of ZmMTP1-1 in yeast further supported its conserved role in Cd tolerance. Collectively, these findings indicate that ZmMTP1-1 and ZmMTP1-2 contribute to Cd detoxification through coordinated metal transport and stress-response pathways, providing potential genetic resources for improving heavy metal tolerance in maize. Full article

Heavy metal-associated isoprenylated plant protein (HIPP) family genes are known to be involved in plant development and stress responses. Even though the HIPPs have been identified and characterized in some plants, the roles of these genes in plant abiotic stress tolerance remain unclear in G. soja (Glycine soja), especially in response to alkaline stress. In the present study, a total of 79 potential HIPP family genes were obtained in G. soja using the Hidden Markov Model. Bioinformatics analysis was used to explore their physicochemical properties, gene structure, phylogenetic relationships, cis-acting elements, chromosomal location and collinearity. Expression profiling showed that 18 HIPP family genes were displayed significantly different transcript levels under alkaline stress, among which GsHIPP79 was selected for functional characterization. The results showed that GsHIPP79 exhibited enhanced alkaline stress tolerance in transgenic Arabidopsis plants, as evidenced by it exhibiting higher chlorophyll contents, strengthening the antioxidant defense system, and regulating the expression of stress-responsive marker genes. Moreover, overexpression of GsHIPP79 in transgenic soybean hairy roots conferred enhanced alkaline stress tolerance. In conclusion, this study provided valuable information on HIPP family genes in G. soja and identified the positive roles of GsHIPP79 in response to alkaline stress tolerance. Full article

Chromium (Cr) is a common heavy-metal pollutant that poses a significant threat to both the environment and human health. Herein, a novel strain Lysinibacillus capsici FPHNCRA4-48, with a high Cr tolerance and removal performance, was isolated from Cr-contaminated plant water in Changde, Hunan Province. Structural characterization and proteomic analyses were performed to investigate the Cr removal performance and molecular mechanism of L. capsici FPHNCRA4-48. FPHNCRA4-48 can effectively remove more than 99% of the Cr(VI) at an initial concentration of 1000 μmol/L. The FTIR, 3D-EEM, and XPS results revealed that -OH, -NH₂, and -CO-NH₂ derived from extracellular polymeric substances (EPSs) were mainly involved in Cr(VI) removal. Interestingly, the protein content in the EPS increased significantly (1.32-fold) after exposure to Cr(VI). Moreover, proteomic analysis revealed that genes (rpmA, rpmI, rpmC, rplI, rpmD, deoB, deoC) related to translation and carbohydrate metabolism, and genes (pyk, icd, rpiB, eno) related to amino acid biosynthesis were all significantly up-regulated, suggesting that these pathways related to protein synthesis in L. capsici FPHNCRA4-48 were activated under Cr(VI) stress. Finally, KEGG ribosome pathway enrichment occurred. These data highlight the importance of microbial EPSs in bioremediation in Cr-polluted environments. This study identified highly efficient Cr(VI)-removing bacterial strains and conducted an in-depth analysis of the removal mechanism of their extracellular polymeric substances (EPSs), thereby providing theoretical foundations and technical support for the biological remediation of Cr(VI)-contaminated water bodies. Full article

Cadmium (Cd) is a highly toxic heavy metal that severely impairs plant growth and poses ecological and health risks. Chrysanthemum indicum (L.), a dominant species in Cd-contaminated regions, represents a valuable germplasm for phytoremediation. In this study, we cloned and characterized CiWRKY50, a WRKY transcription factor containing a conserved WRKY domain and C2H2-type zinc finger. CiWRKY50 was localized to the nucleus but lacked intrinsic transcriptional activation activity. Overexpression of CiWRKY50 in Arabidopsis thaliana and C. indicum significantly enhanced Cd tolerance, as shown by reduced root Cd accumulation, improved transport efficiency, lower ROS and MDA levels, and increased chlorophyll, proline, and soluble protein contents. Antioxidant enzyme activities and Cd-chelating compounds (GSH, NPT, PCs) were also upregulated. Furthermore, combined Cd and ABA treatments promoted Cd sequestration in roots and activated ABA-responsive genes (CiABF1, CiABF2, CiABF4), alleviating shoot toxicity. These findings indicate that CiWRKY50 enhances Cd tolerance in association with enhanced ABA-mediated signaling and redox homeostasis, providing new insights for breeding Cd-resistant plants and improving phytoremediation strategies. Full article