Search Results (393)

Copper is a crucial cofactor that sustains multiple cellular electron-transfer reactions, making it an essential element for life. However, cytotoxic levels of copper can cause structural damage and cell death through the production of reactive oxygen species (ROS) and nonspecific attacks on proteins. Moreover, immune cells, including neutrophils and macrophages, accumulate copper to induce oxidative bursts that kill engulfed pathogens. Therefore, a well-regulated copper homeostasis system is required for the human commensal fungus Candida albicans to thrive in extreme host environments. Remarkably, C. albicans exhibits higher copper tolerance than the nonpathogenic model yeast Saccharomyces cerevisiae, suggesting the presence of a specific copper tolerance mechanism that supports its adaptability to copper stress. Ndt80 is a versatile transcription factor that regulates several biological processes in C. albicans, ranging from morphological control to drug resistance. This study further reveals that Ndt80 may contribute to copper tolerance by regulating copper transporters and copper-dependent superoxide dismutases (Sods). Additionally, RNA sequencing and complementary approaches uncovered the involvement of Ndt80 in plasma membrane integrity and mitochondrial respiration under copper stress, further linking Ndt80 to copper tolerance. Together, these results broaden our understanding of Ndt80 functions and provide new insights into copper tolerance in C. albicans. Full article

Filamentous fungi exhibit high heavy metal resistance; elucidating their resistance mechanisms is of practical importance for fungal utilization and for engineering other microorganisms. However, the molecular basis of copper tolerance in filamentous fungi remains poorly understood, with few studies addressing this specific trait. Previously, we isolated a copper-hyper-resistant strain, P. janthinellum GXCR, and generated two mutagenized derivatives, EC-6 and UC-8. To investigate copper resistance, wild-type GXCR (WT) and mutants EC-6 and UC-8 were subjected to integrated physiological, biochemical, and transcriptomic analyses. Copper tolerance followed the rank order: WT > UC-8 > EC-6. Supplementation with Mn²⁺ or exogenous proline enhanced copper resistance. Under copper stress, intracellular reactive oxygen species (ROS) levels increased in all strains, correlating dynamically with activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as malondialdehyde (MDA) content, with all exhibiting a biphasic response: an initial rise followed by a decline with increasing Cu²⁺ concentration. WT accumulated less Cu and Cd but more Cr (at high concentration) than the mutants. In contrast, intracellular Pb accumulation in all three strains decreased monotonically with rising Pb doses. RNA-seq of WT and EC-6 grown in TYB with 0, 0.5 and 3 mM Cu²⁺ identified 8 copper-resistance-related genes, verified by real-time quantitative reverse transcription PCR (RT-qPCR). Weighted gene co-expression network analysis (WGCNA) clustered genes into 10 modules; integrating physiological data identified 10 traits, and the four most correlated modules yielded 116 hub genes mostly linked to energy metabolism, cell components and transporters. copA and ATP7, encoding Cu²⁺-exporting ATPases, were identified as central regulators of copper homeostasis and key contributors to enhance copper tolerance. These findings provide molecular insights into copper resistance of filamentous fungi and valuable genetic targets for rational strain engineering. Full article

Background/Objectives: Mango bacterial angular leaf spot, caused by Xanthomonas citri pv. mangiferaeindicae (Xcm), is one of the most destructive bacterial diseases of mango, resulting in significant economic losses to the mango industry. Copper-based bactericides have been widely used for decades to control this disease, leading to increased copper resistance in the pathogen and heightened environmental risks. However, the copper resistance mechanisms of Xcm remain incompletely understood. Methods: In this study, we used Xcm GXBS06 isolated from major mango cultivars in Guangxi, China. We analyzed the homologs of known copper resistance-related genes in Xcm and found that these genes are relatively conserved across different strains. The functions of six important known copper resistance gene homologs in Xcm were investigated. Among them, five were functionally characterized by gene deletion, while the remaining one was characterized by overexpression because deletion was unsuccessful. Results: The result showed that copB is a critical copper resistance-related gene in Xcm. However, its deletion neither affects H₂O₂ tolerance nor virulence determinants such as extracellular polysaccharide production, biofilm formation, or cell motility. Additionally, it did not impact pathogenicity or bacterial growth within the host. The expression of copB was significantly induced at copper sulfate concentrations of 0.2 mM and 0.6 mM. Conclusions: These findings contribute to a better understanding of the copper resistance mechanisms in Xcm and provide a foundation for further studies on the biological control of this pathogen. Full article

Non-specific Lipid Transfer Proteins (nsLTPs) constitute a ubiquitous family of plant proteins that play a critical role in mediating plant adaptation and tolerance to abiotic stress. While their functions have been extensively characterized in model plants such as Arabidopsis thaliana and rice (Oryza sativa L.), they remain largely unexplored in Cucurbitaceae crops. We identified 31 CmnsLTP genes in the melon (Cucumis melo L.) genome, these genes were unevenly distributed across 11 chromosomes and classified into 8 subfamilies. Members of the same subfamily have similar gene structures and conserved domains, with all family members having motif 1 and motif 3. The promoter region contains cis elements that respond to light, hormones (ABA and MeJA response elements), and abiotic stress, suggesting that this gene is involved in melon growth, development, and stress response. Previous studies have identified copper resistant candidate MELO3C031073.2 through forward genetics, which belongs to the nsLTP family and was named CmnsLTPY.9 in this study. The RT qPCR results showed that the CmnsLTPY.9 exhibited specific expression in different tissues, The expression levels of CmnsLTPY.9 in leaves ranged from 0.3 to 3.2. Under copper stress, the ‘M625’ (copper-sensitive) showed a 3.2-fold increase, indicating marked upregulation. Additionally, CmnsLTPY.9 was localized to the endoplasmic reticulum, and the position remains unchanged after copper stress. This study provides the first systematic analysis of the CmnsLTP gene family in melon; these findings provide fundamental insights into their specific functions in plant development and stress response, as well as valuable genetic resources for future research on copper-tolerant molecular breeding. Full article

Artemisia maritima holds potential applications in the rehabilitation of degraded environments, particularly in salt-affected areas, for biosaline agriculture aimed at biomass production for further valorization and green biotechnology. The aim of the present study was to investigate the response of A. maritima to alterations in soil chemical composition, including differences in mineral supply, the addition of various sodium salts, and contamination with several heavy metals (cadmium, lead, copper, manganese, zinc), in order to establish a scientific basis for further applied research. Under standard fertilization conditions, the growth of A. maritima plants was restrained by nitrogen deficiency. Surplus nitrogen enhanced mineral uptake and growth, especially for shoots, and stimulated clonal development. Low to moderate (50 and 100 mmol L⁻¹) NaNO₃ treatment significantly stimulated shoot growth, while Na₂HPO₄ and NaHCO₃ treatments exhibited the most adverse effects at 200 and 400 mmol L⁻¹, resulting in reduced growth and biomass, and even the deterioration of the aboveground parts. Chlorophyll fluorescence parameters served as reliable early indicators of the detrimental effects of salinity associated with individual anions. Shoot macronutrient levels remained unchanged for phosphorus and calcium, while nitrogen increased in nitrate treatments. Root mineral nutrient content was more susceptible to salinity, with significant changes observed for all macro- and micronutrients, varying depending on the specific element and anion type. The alterations in mineral nutrition observed for each anion treatment exhibited distinct characteristics. A. maritima plants demonstrated high tolerance to all heavy metals, with roots being more susceptible compared to shoots. At the shoot level, statistically significant growth inhibition was evident only for 1000 mg L⁻¹ lead and 1000 mg L⁻¹ zinc treatments. A. maritima plants can be characterized as high accumulators of cadmium, lead, manganese, and zinc, and as extreme accumulators of copper in shoots. Nitrophily, clonal expansion with a help of bud-bearing roots, and the ability to accumulate relatively high concentrations of mineral elements in shoots are among the important physiological characteristics of A. maritima plants, enabling them to exhibit high resilience in environmentally heterogeneous habitats. Full article

Environmental pollution caused by persistent chemical compounds, particularly heavy metals, poses a significant global challenge. Current strategies focus on eco-friendly and sustainable approaches, such as the application of microorganisms, to mitigate this issue. In this study, four strains of Bacillus and Pseudomonas were phylogenetically identified and assessed for their resistance to three heavy metals: copper (Cu), chromium (Cr), and cadmium (Cd) up to 500 µg/mL. Various tolerance mechanisms related to heavy metal resistance were elucidated, including salinity tolerance, antibiotic resistance, production of exopolysaccharides (EPS), and biosurfactant synthesis. The antifungal activities of these strains were evaluated against the fungal isolates Fusarium oxysporum fs. phaseoli (Fop) and Stemphylium botryosum (St-bt) using dual culture assays. Phylogenetic analysis revealed that three strains belong to the genus Bacillus, while one strain is classified under Pseudomonas. Additionally, these strains exhibited diverse mechanisms for heavy metal tolerance, including salinity tolerance (up to 600 mM), multi-antibiotic resistance (to imipenem, ampicillin, and sodium fusidate), and the production of viscous, slimy colonies indicative of EPS synthesis. Biosurfactant production led to a significant reduction in surface tension, ranging from 10.51 ± 3.87% to 82.89 ± 5.01%. The antifungal assays demonstrated that the strains effectively inhibited the mycelial growth of the fungal isolates, with inhibition percentages varying from 0% to 83.34 ± 2.22%. The strains characterized in this study exhibit considerable potential for application in the bioremediation of metal-contaminated soils and as biocontrol agents. Full article

Trifoliate orange (Poncirus trifoliata L.) is one of the most widely utilized rootstocks in citrus production; however, it exhibits a relatively high sensitivity to salt stress. When cultivated in salinized soil, it frequently develops nutrient uptake disorders, leaf chlorosis, as well as reduced fruit yield and quality. To enhance the salt stress tolerance of citrus plants, this study investigated the effects of Trichoderma harzianum inoculation on the growth and response mechanisms of citrus seedlings under salt stress conditions. The results showed that salt stress significantly inhibited the growth of citrus seedlings, while T. harzianum inoculation effectively alleviated the inhibitory effect. After treatment with T. harzianum, the plant height, stem diameter, leaf number, and biomass of citrus seedlings increased significantly. The net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, transpiration rate, and chlorophyll content were significantly increased by T. harzianum inoculation. Meanwhile, T. harzianum inoculation increased the content of nitrogen, phosphorus, calcium, magnesium, zinc, and copper, and decreased sodium content in citrus seedlings. In addition, T. harzianum inoculation significantly up-regulated the expression of stress-responsive genes such as SOSs, PIPs, TIP1, TIP4, and TIP9. In conclusion, T. harzianum inoculation improved the salt stress tolerance of citrus seedlings through increasing photosynthetic efficiency, promoting nutrient absorption, sodium efflux, and water utilization via up-regulating the expression of SOSs and aquaporin genes. Full article

Nitric oxide (NO) is recognized as a key signaling molecule involved in plant tolerance to abiotic stress. Yet, its role in regulating cadmium (Cd) detoxification and ion homeostasis remains insufficiently understood across different lettuce genotypes. This study aimed to elucidate the NO-mediated mechanisms underlying Cd stress mitigation by focusing on oxidative regulation, ion balance, and Cd accumulation dynamics in lettuce. Three lettuce varieties (Lactuca sativa L.), namely curly (var. crispa), romaine (var. longifolia), and iceberg (var. capitata), were exposed to 100 and 500 µM Cd, with or without 200 µM sodium nitroprusside (SNP), under controlled greenhouse conditions in a modified Hoagland solution. Growth traits, antioxidant enzyme activities [catalase (CAT) and ascorbate peroxidase (APX)], oxidative stress markers [hydrogen peroxide (H₂O₂), malondialdehyde (MDA), membrane permeability (MP), and proline], ionic homeostasis [potassium (K), calcium (Ca), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn)], and Cd accumulation indices [bioconcentration factor (BCF), translocation factor (TF), total accumulation rate (TAR), and net accumulation via roots (NetAcc)] were evaluated. Cd exposure significantly reduced biomass production, photosynthetic pigment contents, and the accumulation of essential mineral nutrients, while markedly increasing oxidative stress indicators. Antioxidant responses varied among varieties, with Cd generally stimulating CAT activity but suppressing APX, indicating redox imbalance. SNP application partially restored antioxidant enzyme activities, reduced membrane damage, and alleviated oxidative stress in a genotype-dependent manner. Cd accumulation indices revealed substantial Cd uptake and translocation, particularly in curly and iceberg lettuce. SNP significantly reduced BCF, TF, TAR, and NetAcc values, suggesting NO-mediated restriction of Cd mobility, possibly through enhanced root sequestration and detoxification processes. Moreover, SNP improved K⁺, Ca²⁺, Fe²⁺, and Mn²⁺ homeostasis, highlighting its role in maintaining selective ion transport under Cd stress. Among the tested varieties, curly lettuce exhibited the highest NO-induced tolerance, followed by iceberg and romaine lettuce. Overall, the findings demonstrate that NO acts as an effective regulator of redox balance, ion homeostasis, and Cd detoxification, thereby enhancing physiological resilience and reducing Cd accumulation in lettuce exposed to Cd stress. From a sustainability perspective, these findings highlight the potential of NO application as an effective strategy to reduce Cd accumulation in leafy vegetables, thereby contributing to safer food production and more sustainable crop management under heavy metal-contaminated conditions. Full article

This study presents a novel multifunctional Lac@CMC-Cu@Fe₃O₄ nanocomposite for the efficient immobilization of laccase designed to overcome limitations in enzyme stability, reusability, and catalytic performance. The nanocomposite integrates magnetite (Fe₃O₄) for rapid magnetic separation, carboxymethyl cellulose (CMC) as a biocompatible matrix for covalent enzyme attachment, and copper nanoparticles to enhance catalytic activity. The immobilization achieved an impressive yield of 87%, with comprehensive characterization by XRD, FT-IR, FESEM, EDX, BET, and VSM confirming successful synthesis and enzyme attachment. Kinetic analysis revealed a remarkable 37% increase in maximum reaction velocity (Vmax = 111 µmol/min) compared to free laccase (81.3 µmol/min), despite a moderate increase in Km from 1.54 to 3.22 mM. The immobilized biocatalyst demonstrated superior thermal stability, retaining 53% activity at 60 °C versus 17% for the free enzyme, and exhibited a broader pH tolerance, maintaining 41% activity at pH 8.0. Notably, the biocatalyst showed enhanced performance in organic solvents, with 153% activation in acetone. Operational reusability was exceptional, retaining 84% activity after 15 cycles, and storage stability was significantly improved, maintaining 68% activity after 90 days compared to only 11% for free laccase. This magnetically separable nanobiocatalyst represents a promising, scalable platform for sustainable industrial and environmental applications. Full article

Heavy metals such as copper are commonly found in aquatic environments. Microalgae can effectively adsorb heavy metals, while high concentrations impair their physiological and biochemical processes. This research investigated the impact of varying concentrations of sodium thiosulfate (Na₂S₂O₃) on the heavy metal tolerance of Chlorella vulgaris. Results showed that Na₂S₂O₃ and copper ions Cu(II) co-stress significantly improved the tolerance of C. vulgaris to Cu(II). To explore the mechanism, weighted gene co-expression network analysis (WGCNA) and trend analysis were applied to study the gene regulatory network under combined stress. A total of 103 significantly differentially expressed genes (DEGs) were identified. Further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that the majority of DEGs are associated with photosynthesis, energy and liposome metabolisms. Physiological metrics, including chlorophyll content, photosynthetic activity, malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT), also aligned with bioinformatics results. This research offers a promising approach to reduce heavy metal pollution in water bodies. Full article

Biocontrol, a practice for using living organisms to target plant pathogens, offers a promising, sustainable agricultural strategy. This study involves epiphytic yeasts isolated from Vitis vinifera ssp. sylvestris and ssp. vinifera as natural antagonists against Aspergillus carbonarius, Botrytis cinerea, and Penicillium expansum. Twenty-one of 37 yeasts were chosen based on the Pathology Intensity (PA) score during preliminary in vivo screening. Following identification, dual-culture assays, VOC production, copper tolerance, and commercial fungicide resistance were assessed. On YPD and GJ medium, Saccharomyces isolates were the strongest antagonists, whereas P. terricola UMY197 inhibited Penicillium and Aspergillus. H. uvarum UMY1473 was notably effective against B. cinerea. VOC analysis confirmed that S. cerevisiae UMY1430 was the most effective against Aspergillus, likely owing to its production of oxalic acid, while S. cerevisiae UMY1438 was a producer of various esters and phenylethyl alcohol. C. intermedia UMY189, M. pulcherrima UMY1472, H. uvarum UMY1473, and S. cerevisiae UMY1436 were the most copper-resistant. Yeast activity on chemical fungicide SWITCH (up to 1 g/L) depended on culture media usage; in fact, a higher viability on YPD than on GJ was observed, where only 4 yeasts were able to grow. Thus, since several yeasts exhibit promising inhibitory activity through various mechanisms and against different molds, the use of synthetic consortia could represent a powerful and essential tool in field trials to limit fungicide use while preventing the emergence of resistance. Full article

Bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa) is a major threat to global kiwifruit production. Copper-based bactericides remain widely used, but increasing resistance highlights the urgency of developing sustainable alternatives. Understanding the functional capabilities of phyllosphere bacteria under copper pressure is critical for designing microbiome-informed management strategies. This study provides a culture-based functional inventory of bacteria associated with Actinidia chinensis var. deliciosa leaves from Portuguese orchards under long-term copper management, aiming to identify native taxa with traits relevant to plant health and resilience. A total of 1058 isolates were recovered and grouped into 261 Random Amplification of Polymorphic DNA (RAPD) clusters, representing 58 species across 29 genera. Representative strains were screened for Plant Growth-Promoting (PGP) traits (Indole-3-acetic acid (IAA), siderophore production, phosphate solubilization, ammonia production), copper tolerance, and in vitro antagonism against Psa. Copper resistance was widespread (53.3% of isolates with MIC ≥ 0.8 mM), including the first evidence of a highly copper-resistant PSA strain in Portuguese kiwifruit orchards and an exceptionally resistant non-pathogenic strain closely related to Erwinia iniecta (MIC 2.8 mM). A subset of 25 isolates combined all four PGP traits, and several also exhibited antagonism against Psa in vitro, among them Bacillus pumilus consistently supressed pathogen growth. Notably, antagonistic and multifunctional traits co-occurred in some isolates, highlighting promising candidates for integrated biocontrol strategies. Overall, the findings reveal a functionally diverse and copper-resilient collection of cultured bacteria, offering both challenges and opportunities for microbiome-based disease management. This work establishes a robust functional basis for subsequent in planta validation and the development of sustainable, microbiome-informed approaches for Psa control. Full article

The performance of conventional precipitation-strengthened copper alloys drastically degrades at temperatures exceeding 500 °C, hindering their application under extreme conditions like those in nuclear fusion reactors. Oxide dispersion–strengthened copper (ODS–Cu) alloy surmounts these constraints by incorporating thermally stable, nanoscale oxide dispersoids that simultaneously confer strengthening, microstructural stabilization, and enhanced irradiation tolerance, while preserving high thermal conductivity. This review comprehensively examines the state of the art in ODS–Cu alloy from a “processing–microstructure–property” perspective. We critically assess established and emerging fabrication routes, including internal oxidation, mechanical alloying, wet chemical synthesis, reactive spray deposition, and additive manufacturing, to evaluate their efficacy in achieving uniform dispersions of coherent/semi-coherent nano-oxides at engineering-relevant scales. The underlying strengthening mechanisms and performance trade-offs are quantitatively analyzed. The review also outlines strategies for joining and manufacturing complex components, highlights key gaps in metrology and reproducibility, and proposes a roadmap for research and standardization to accelerate industrial deployment in plasma-facing components. Full article

Functional properties of coastal halophytes are important for development of salt-tolerant cash crop cultures. The study of salt tolerance in coastal dune-building grass Leymus arenarius holds significant importance for its application in land reclamation, soil stabilization, and enhancing crop resilience to salinity stress. We used two accessions (LA1 and LA2) of L. arenarius to compare effects of salinity caused by NaCl and NaNO₃ on growth, ion accumulation and mineral nutrition in controlled conditions. L. arenarius plants exhibited high tolerance to sodium salts, with distinct effects on growth and development observed between chloride and nitrate treatments. While both salts negatively impacted root biomass, nitrate treatment (50–100 mmol L⁻¹) increased leaf number and biomass in LA2 plants, whereas chloride treatment decreased tiller and leaf sheath biomass. Despite individual variations, salinity treatments showed comparable effects on traits like tiller and leaf count, as well as leaf blade and sheath biomass. Salinity increased water content in leaf blades, sheaths, and roots, with LA2 plants showing the most pronounced effects. Chlorophyll a fluorescence measurements indicated a positive impact of NaNO₃ treatment on photosynthesis at intermediate salt concentrations, but a decrease at high salinity, particularly in LA2 plants. The accumulation capacity for Na⁺ in nitrate-treated plants reached 30 and 20 g kg⁻¹ in leaves and roots, respectively. In contrast, the accumulation capacity in chloride-treated plants was significantly lower, approximately 10 g kg⁻¹, in both leaves and roots. Both treatments increased nitrogen, phosphorus, and manganese concentrations in leaves and roots, with varying effects on calcium, magnesium, iron, zinc, and copper concentrations depending on the type of salt and tissue. These findings highlight the potential of L. arenarius for restoring saline and nitrogen-contaminated environments and position it as a valuable model for advancing research on salt tolerance mechanisms to improve cereal crop resilience. Full article

Mechanical and thermoelectric performance of a SiGe thermoelectric module were investigated through finite element analysis. N-type and P-type SiGe thermoelectric materials were synthesized, and their mechanical and thermoelectric properties were experimentally measured. Thermal stress distributions within the SiGe module and the integrated “heat collector–module–heat sink” assembly are simulated, and the results were compared with the measured mechanical strength of the SiGe materials. The simulations show that among the three electrode structures evaluated—C/W/C sandwich, 0.5 mm W/C, and 0.1 mm W/C—the C/W/C sandwich configuration yields the lowest thermal stress. An inter-leg spacing of 0.5 mm also leads to reduced stress compared to a 0.1 mm gap. However, fully constraining the cold end or directly integrating the module with heat collection and dissipation components significantly increases thermal stress. The use of copper cooling plates induces higher stress than C-C plates, exceeding the tolerable strength of the materials. Simulation of a module with 28 SiGe legs (each 10 mm × 10 mm × 1.5 mm) predicts an output power of 7.42 W and a conversion efficiency of 7.11% at a hot-side temperature of 967 °C and a cold-side temperature of 412 °C. Full article