Search Results (488)

As chemical messengers, phytohormones can enhance the tolerance of plants to stress caused by toxic elements (TEs) such as cadmium (Cd), lead (Pb), and zinc (Zn). This study investigated the combined toxicity of Cd, Pb, and Zn, and its impact on stress phytohormones (jasmonates, salicylic acid, and abscisic acid), in oat (Avena sativa L.) using anthropogenically contaminated soil in a 4-week pot experiment. The uptake of TEs by the roots increased in the multi-contaminated soil, while Zn was the only TE to be translocated to the leaves. The toxic effect of the TEs was assessed in terms of plant growth, revealing a decline in leaf dry biomass, whereas the impact on the roots was insignificant. These findings align with the levels of stress phytohormones. An increase in bioactive forms of stress phytohormones in leaves due to TEs indicates TE toxicity and leaf sensitivity. Conversely, low levels of these phytohormones, along with crosstalk between them, suggest reduced defense against TEs in the roots. The abundance of stress phytohormones declined in the following order: salicylic acid > jasmonates > abscisic acid. These results help to understand the mechanism by which plants respond to TEs, particularly their combined toxicity. Full article

Arbuscular mycorrhizal fungi (AMF) demonstrate considerable potential for remediating soils contaminated with heavy metals. However, comprehensive research examining the effects of cadmium (Cd) contamination on AMF communities in paddy fields remains scarce, constraining their broader application in such environments. In this study, high-throughput sequencing was utilized to assess AMF community structure in paddy soils subjected to five distinct levels of Cd contamination. The study also explored the effect of different soil properties on AMF community dynamics. A total of 188 AMF taxa were identified across all soil samples, spanning four families. The Claroideoglomeraceae family emerged as the predominant group, exhibiting notable Cd tolerance. While elevated Cd concentrations inhibited the AMF community structure, lower concentrations increased the α-diversity of the community. Furthermore, soil-available phosphorus, calcium levels, and pH were found to be critical factors driving shifts in AMF community structure. Redundancy analysis explicitly quantified the relative strength of environmental factors, demonstrating that phosphorus and pH directly influenced the AMF community structure through significant effects, while Cd and calcium exerted their influence via indirect or nonlinear pathways. Given the relative abundance advantage of Claroideoglomeraceae in Cd-contaminated environments and its positive correlation with Cd concentration, we hypothesize that this group may exhibit Cd tolerance. Therefore, it could be considered a potential candidate species for prioritization in future field inoculation trials, and its practical application potential should be further validated. Full article

Wild edible mushrooms are increasingly recognised for their nutritional and therapeutic potential, owing to their richness in bioactive compounds and antioxidant properties. This study assessed the chemical composition, antioxidant capacity, and bioaccumulation of heavy metals (Cd, Pb, Ni) in Boletus edulis, Imleria badia, and Leccinum scabrum collected from two forested regions of north-western Poland differing in anthropogenic influence and soil characteristics. The analysis encompassed structural polysaccharides (β- and α-glucans, chitin), carotenoids, L-ascorbic acid, phenolic and organic acids. B. edulis exhibited the highest β-glucan and lycopene contents, but also the greatest cadmium accumulation. I. badia was distinguished by elevated ascorbic and citric acid levels and the strongest DPPH radical scavenging activity, while L. scabrum showed the highest ABTS and FRAP antioxidant capacities and accumulated quinic acid and catechin. Principal component analysis indicated strong correlations between antioxidant activity and phenolic acids, while cadmium levels were inversely associated with antioxidant potential and positively correlated with chitin. Although all metal concentrations remained within EU food safety limits, B. edulis showed consistent cadmium bioaccumulation. From a practical perspective, the results highlight the importance of species selection and sourcing location when considering wild mushrooms for consumption or processing, particularly in the context of nutritional value and contaminant load. Importantly, regular or excessive consumption of B. edulis may result in exceeding the tolerable weekly intake (TWI) levels for cadmium and nickel, which warrants particular attention from a food safety perspective. These findings underscore the influence of species-specific traits and environmental conditions on mushroom biochemical profiles and support their potential as functional foods, provided that metal contents are adequately monitored. Full article

Heavy metal pollution represents a pervasive environmental challenge that significantly exacerbates the ever-increasing crisis of antimicrobial resistance and the capacity of microorganisms to endure and proliferate despite antibiotic interventions. This review examines the intricate relationship between heavy metals and AMR, with an emphasis on the underlying molecular mechanisms and ecological ramifications. Common environmental metals, including arsenic, mercury, cadmium, and lead, exert substantial selective pressures on microbial communities. These induce oxidative stress and DNA damage, potentially leading to mutations that enhance antibiotic resistance. Key microbial responses include the overexpression of efflux pumps that expel both metals and antibiotics, production of detoxifying enzymes, and formation of protective biofilms, all of which contribute to the emergence of multidrug-resistant strains. In the soil environment, particularly the rhizosphere, heavy metals disrupt plant–microbe interactions by inhibiting beneficial organisms, such as rhizobacteria, mycorrhizal fungi, and actinomycetes, thereby impairing nutrient cycling and plant health. Nonetheless, certain microbial consortia can tolerate and detoxify heavy metals through sequestration and biotransformation, rendering them valuable for bioremediation. Advances in biotechnology, including gene editing and the development of engineered metal-resistant microbes, offer promising solutions for mitigating the spread of metal-driven AMR and restoring ecological balance. By understanding the interplay between metal pollution and microbial resistance, we can more effectively devise strategies for environmental protection and public health. Full article

Cadmium (Cd) is a highly toxic heavy metal that can greatly affect crops and pose a threat to food security. Plant growth-promoting rhizobacteria (PGPR) are capable of alleviating the harm of Cd to crops. In this research, a Cd-tolerant PGPR strain was isolated and screened from the root nodules of semi-wild soybeans. The strain was identified as Pseudomonas sp. strain KM25 by 16S rRNA. Strain KM25 has strong Cd tolerance and can produce indole-3-acetic acid (IAA) and siderophores, dissolve organic and inorganic phosphorus, and has 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. Under Cd stress, all growth indicators of soybean seedlings were significantly inhibited. After inoculation with strain KM25, the heavy metal stress of soybeans was effectively alleviated. Compared with the non-inoculated group, its shoot height, shoot and root dry weight, fresh weight, and chlorophyll content were significantly increased. Strain KM25 increased the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities of soybean seedlings, reduced the malondialdehyde (MDA) content, increased the Cd content in the roots of soybeans, and decreased the Cd content in the shoot parts. In addition, inoculation treatment can affect the community structure of endophytic bacteria in the roots of soybeans under Cd stress, increasing the relative abundance of Proteobacteria, Bacteroidetes, Sphingomonas, Rhizobium, and Pseudomonas. This study demonstrates that strain KM25 is capable of significantly reducing the adverse effects of Cd on soybean plants while enhancing their growth. Full article

Asia minor bluegrass (Polypogon fugax), a widespread Poaceae weed, exhibits broad tolerance to abiotic stresses. Validated reference genes (RGs) for reliable RT-qPCR normalization in this ecologically and agriculturally significant species remain unidentified. This study identified eight candidate RGs using transcriptome data from seedling tissues. We assessed the expression stability of these eight RGs across various abiotic stresses and developmental stages using Delta Ct, BestKeeper, geNorm, and NormFinder algorithms. A comprehensive stability ranking was generated using RefFinder, with validation performed using the target genes COR413 and P5CS. Results identified EIF4A and TUB as the optimal RG combination for normalizing gene expression during heat stress, cold stress, and growth stages. EIF4A and ACT were most stable under drought stress, EIF4A and 28S under salt stress, and EIF4A and EF-1 under cadmium (Cd) stress. Furthermore, EIF4A and UBQ demonstrated optimal stability under herbicide stress. Additionally, application of validated RGs revealed higher acetyl-CoA carboxylase gene (ACCase) expression in one herbicide-resistant population, suggesting target-site gene overexpression contributes to resistance. This work presents the first systematic evaluation of RGs in P. fugax. The identified stable RGs provide essential tools for future gene expression studies on growth and abiotic stress responses in this species, facilitating deeper insights into the molecular basis of its weediness and adaptability. Full article

Suaeda salsa is relatively tolerant to cadmium (Cd) contamination. In order to investigate the bioaccumulation and stress responses of S. salsa under chronic exposure, we explored the growth, accumulation, and changes in antioxidant enzymes and glutathione (GSH) under different Cd concentrations over a 30-day soil culture experiment. Seedling height and weight in the 13.16 mg/kg Cd group were 13.26 cm and 0.21 g, significantly higher than the control group. Growth was significantly inhibited under high Cd concentration exposure, with a seedling and root length of 9.65 cm and 3.77 cm. The Cd concentration in all tissues was positively related to Cd treatment concentration, with the Cd contents in the roots being higher than in the other tissues. At a subcellular level, Cd was mainly concentrated in the cell walls, organelles, and soluble components within the range of 0.05–8.29, 0.02–2.40 and 0.08–1.35 μg/g, respectively. The accumulation of Cd in the roots tracked its proportion in the cell walls. The malondialdehyde (MDA) content of the plant tissues increased with increasing Cd concentration, indicating that Cd stress caused oxidative damage. The GSH content increased with increasing Cd concentration, with maximum values of 0.515 μmol/g in the stem in the 66.07 mg/kg Cd group. The catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) activity showed different change trends under Cd exposure. The results in this study could provide useful information on the tolerance mechanism of Cd in S. salsa, which provides information for exploiting S. salsa as a candidate for phytoremediation of Cd contamination. Full article

Phytoremediation is a green economic method to address soil cadmium (Cd) pollution, and Solanum americanum is considered a potential phytoremediation candidate. However, the underlying Cd response mechanisms of S. americanum remain unclear. In the current study, a hydroponic experiment with 160 μmol/L Cd stress was conducted, physiological and molecular indices were measured to explore the response of S. americanum leaves to Cd stress at different time points (0, 3, and 7 days). Our findings revealed that Cd stress inhibited plant growth. Moreover, Cd stress significantly increased Cd accumulation, as well as Chla content, Chla/b, activities of SOD and POD, and elevated MDA content in the leaves. Furthermore, transcriptomics, proteomics, and metabolomics analyses revealed 17,413 differentially expressed genes (DEGs), 1421 differentially expressed proteins (DEPs), and 229 differentially expressed metabolites (DEMs). Meanwhile, integrative analyses of multi-omics data revealed key proteins involved in response to Cd stress, including POD, PAL, F5H, COMT, and CAD for phenylpropanoid biosynthesis, as well as GAPA, FBP, and FBA for photosynthesis pathways. Additionally, conjoint analyses highlighted that upregulated phenylpropanoid metabolism and photosynthesis alleviated Cd toxicity, playing vital roles in enhancing Cd tolerance in leaves. A conceptual molecular regulatory network of leaves in the response to Cd toxicity was proposed. This comprehensive study will provide detailed molecular-scale insights into the Cd response mechanisms in S. americanum. Full article

The DNA mismatch repair (MMR) system plays a crucial role in repairing DNA damage and regulating cell cycle arrest induced by cadmium (Cd) stress. To elucidate the mechanism by which miRNAs target AtMSH2 in regulating Arabidopsis’ response to Cd stress, the wild-type Arabidopsis, Atmsh2 mutant, and three miRNA-overexpressing transgenic lines were grown hydroponically in half-strength MS solution containing cadmium (Cd) at concentrations of 0, 0.5, 1, 2, and 3 mg/L for 5 days. miRNA-seq analysis, bioinformatics prediction, dual-luciferase reporter assays, and qRT-PCR results demonstrated that miR5651, miR170-3p, and miR171a-3p specifically targeted AtMSH2 and their expression levels showed a significant negative correlation. Compared to wild-type (WT) Arabidopsis, Cd stress tolerance was significantly enhanced in miRNA-overexpressing transgenic lines. Moreover, exogenous application of these three miRNAs in half-strength MS liquid medium also markedly improved Cd stress tolerance in wild-type Arabidopsis. Furthermore, the expression of these three miRNAs expression was further upregulated by Cd stress in a dose-dependent manner. Additionally, DNA damage response in miRNA-overexpressing transgenic lines was promoted based on the expression of DNA repair, DNA damage signaling, and cell cycle genes, which differed from both wild-type and Atmsh2 plants. Taken together, miR5651, miR170-3p, and miR171a-3p participated in Cd stress response and improved plant Cd tolerance by mediating the expression of AtMSH2. Our study provides novel insights into the epigenetic mechanisms of Cd tolerance in plants, which sheds light on breeding for stress resilience in phytoremediation. Full article

Background: Phytoremediation is an efficient approach for remediating heavy metal-contaminated soils. Heavy metal-associated isoprenylated plant proteins (HIPPs)—crucial for metal ion homeostasis—are unique to vascular plants, featuring a heavy metal-associated (HMA) domain and an isoprenylated CaaX motif. However, ZmHIPP genes have not been systematically or functionally characterized in maize. Methods: This study characterizes ZmHIPP at the genome-wide level, including phylogenetic classification, motif/gene structure, chromosome location, gene duplication events, promoter elements, and tissue expression patterns. Cadmium (Cd) responses were evaluated by specific ZmHIPP expression and Cd accumulation in shoots and roots under Cd treatment. Results: A total of 66 ZmHIPPs were distributed unevenly across ten chromosomes, classified into five phylogenetic groups phylogenetically. Gene collinearity revealed 26 pairs of segmental duplications in ZmHIPPs. Numerous synteny genes were detected in rice and sorghum, but none in Arabidopsis, suggesting high conservation of HIPP genes in crop evolution. Transcriptomic analysis revealed tissue-specific expression patterns of ZmHIPP members in maize. Cis-acting element analysis linked several binding elements to abscisic acid, MeJA response, and MYB and MYC transcription factors. Under Cd stress, 53 out of 66 ZmHIPP genes were significantly induced, exhibiting three expression patterns. Cd exposure confirmed that the expression of ZmHIPP11, ZmHIPP30, and ZmHIPP48 was generally higher in shoots than roots, while ZmHIPP02 and ZmHIPP57 exhibited the opposite. Cd accumulation was higher in roots than shoots, peaking at 72 h (96 mg/kg) in shoots and exceeding 1000 mg/kg in roots after 120 h. Conclusions: This study not only provides fundamental genetic and molecular insights into HIPP function in maize but also identifies specific ZmHIPP genes as promising genetic resources for breeding Cd-tolerant maize, aiding in phytoremediation of Cd-contaminated soils. Full article

Cadmium (Cd) contamination in agricultural soils severely threatens rice production and food safety. To address this issue, this study developed transgenic rice lines co-expressing three Vitis vinifera genes: the ABCC transporter Vvmrp1 and metallothioneins Vvmt1 and Vvmt2. AlphaFold computational modeling confirmed the conserved ABCC-type transporter domain in VvMRP1. Under hydroponic conditions, transgenic rice showed remarkable Cd tolerance, surviving 30 mM Cd (lethal to wildtype, WT) without growth penalties, and exhibited 62.5% survival at 1 mM Cd vs. complete wild-type mortality. Field-relevant Cd exposure (1 mM) reduced Cd accumulation to 35.8% in roots, 83% in stems, and 76.8% in grains compared to WT. Mechanistic analyses revealed that Vvmrp1 mediates cellular Cd efflux while Vvmt1 and 2 chelate free Cd ions, synergistically inhibiting Cd translocation. Transgenic plants also maintained better Fe, P, and Mg homeostasis under Cd stress. This study pioneers the co-expression of a transporter with metallothioneins in rice, demonstrating their complementary roles in Cd detoxification without pleiotropic effects from endogenous gene modification. The findings provide an effective genetic strategy for cultivating low-Cd rice in contaminated soils, offering significant implications for food safety and sustainable agriculture. Full article

Cadmium (Cd) significantly influences the morphological, physiological traits, and transport capacity of plants, but the underlying mechanism of Cd stress still remains to be further studied. In this study, physiological, transcriptomic, and metabolomic analyses were conducted to examine the morphological and physiological traits of two elite maize inbred lines, Chang7_2 (C7_2, a Cd-resistant line) and Zheng58 (Z58, a Cd-sensitive line) under control and Cd stress conditions. The results of morphological traits indicated that C7_2 reduced by 9.50–29.60% under Cd stress, whereas Z58 displayed more pronounced morphological changes ranging from 10.12 to 41.72% under Cd stress. Physiological assessments revealed that C7_2 maintained relatively stable antioxidant enzyme activity, while Z58 demonstrated more rapid alterations in the antioxidant system under Cd stress. Transcriptomic analysis identified 3030 differentially expressed genes (DEGs) unique to C7_2 and 4298 DEGs unique to Z58, with 1746 common DEGs shared between the two lines. Functional annotation revealed that the unique DEGs in C7_2 were mainly enriched in plant hormone signal transduction, plant–pathogen interactions, and the MAPK signaling pathway, while the unique DEGs in Z58 were mainly enriched in ribosome-related functions, plant hormone signal transduction, and phenylpropanoid biosynthesis. Metabolomic analysis identified 12 superclasses encompassing 896 metabolites in C7_2 and Z58, primarily including lipids and lipid-like molecules, organic acids and derivatives, as well as organoheterocyclic compounds. Analysis of differentially accumulated metabolites (DAMs) revealed fewer DAMs were accumulated in C7_2 under Cd stress. Further analysis identified that the three pathways of GPI anchor biosynthesis, glycerophospholipid metabolism, and purine metabolism were among the top 10 metabolic pathways in C7_2 and Z58. The integrative analysis highlighted the crucial roles of phenylpropanoid biosynthesis and zeatin biosynthesis in C7_2 for resistance to Cd stress. This study provides novel insights into the molecular and metabolic pathways underlying Cd tolerance in maize by integrating transcriptomic and metabolomic analyses of two contrasting inbred lines, providing a theoretical foundation for the future breeding of Cd-tolerant varieties. Full article

Heavy metal contamination in soil, especially cadmium (Cd) and lead (Pb), poses serious environmental and health risks, particularly in mining regions. While this contamination affects most organisms present in such areas, some filamentous fungi proliferate and immobilize metals in contaminated areas. In this work, six filamentous fungi tolerant to high concentrations of these metals were identified by macroscopic and microscopic morphological characteristics, as well as molecularly, through conserved regions of internal transcribed spacers (ITSs). Tolerance to Cd and Pb was evaluated in solid and liquid culture media, and half the maximum inhibitory concentration (IC₅₀) was assessed. Pb tolerance was observed in Penicillium simplicissimum, Paecilomyces lilacinus, and Rhizopus microsporus (IC₅₀: 3874, 1176, and 211.80 mg/L). Cd tolerance was also noted in Paecilomyces lilacinus, Fusarium oxysporum, Rhizopus microsporus, and Cunninghamella sp. (IC₅₀: 311, 223, 29.25, and 25.18 mg/L). These findings indicate that these fungi have adopted effective strategies for survival in contaminated environments and emphasize their potential for future applications in the bioremediation of multi-metal-contaminated soils. This research lays the groundwork for exploring tolerance mechanisms and evaluating the efficacy of native fungal isolates in mitigating heavy metal contamination. Full article

With the continuous rise in global temperatures, heat stress has become a significant threat to rice (Oryza sativa L.) growth and yield. MYB transcription factors, the largest family of genes in plants, play a crucial role in mediating responses to various abiotic stresses. However, the specific functions of MYB genes in rice under heat stress remain largely unexplored. In this study, we conducted a comprehensive genome-wide characterization of the MYB transcription factor family and performed an RNA-seq analysis to identify OsMYB genes that are responsive to heat stress. We identified 229 MYB genes in rice, 134 of which exhibited significant expression changes under heat treatment. An RT-qPCR analysis validated the RNA-seq results for 15 MYB genes, confirming significant expression changes, such as the upregulation of Os02g0685200 after heat stress and the downregulation of Os05g0579600. Six highly responsive genes were selected for further analysis. Cis-acting elements associated with hormone response and abiotic stress were identified in the promoter regions of these genes. A subcellular localization analysis revealed that, except for Os05g0579600, which located to both the nucleus and cytoplasm, the other MYB genes (Os01g0192300, Os02g0685200, Os06g0637500, Os06g0669700, and Os09g0106700) were predominantly located in the nucleus. In yeast, Os01g0192300, Os06g0637500, and Os06g0669700 exhibited transcriptional activation activity, while Os02g0685200 and Os09g0106700 showed transcriptional repression activity. Notably, these genes responded not only to heat stress but also to other abiotic stresses, such as cold, salt, and heavy metal cadmium. This study provides valuable insights into the functional roles of OsMYB family genes in the heat stress response, identifying Os01g0192300, Os02g0685200, Os05g0579600, Os06g0637500, Os06g0669700, and Os09g0106700 as potential key genes involved in heat tolerance in rice. Full article

Cadmium (Cd) is a highly hazardous heavy metal that has an extensive impact throughout the world. 2,4-Epibrassinolide (BR) is an endogenous hormone that can enhance plant tolerance to various abiotic stresses. Herein, Vigna angularis cultivar “Zhen Zhuhong” was grown hydroponically and treated with 0, 1, and 2 mg·L⁻¹ cadmium chloride (CdCl₂) at the V1 stage, and foliar sprayed with or without 1 μM BR solution to analyze the effects of BR treatment on the physiology of Vigna angularis seedling leaves under Cd stress. BR treatment significantly alleviated the growth inhibition induced by Cd stress, which was associated with an increase in the plant height (11.15–17.83%), leaf area (35.59–56.72%), leaf dry weight (45.57–50.65%), and above-ground dry weight (50.86–55.17%). In addition, BR treatment induced significant reductions in Cd accumulation across different tissues of V. angularis, with decreases of 20.38–35.93% in leaves, 21.24–32.74% in stems, and 15.38–16.00% in petioles. Compared with the Cd treatment, BR treatment significantly enhanced the activities of peroxidase (5.02–13.22%), ascorbate peroxidase (27.13–70.28%), catalase (20.46–32.30%), and superoxide dismutase (16.54–21.81%), and increased the ascorbic acid content (27.55–45.52%), which contributed to a reduction in the accumulation of reactive oxygen species, cellular membrane damage, and cytoplasmic exosmosis. RNA-seq and real-time quantitative reverse transcription PCR analyses revealed that the BR treatment under Cd stress significantly upregulated the expression of genes involved in chlorophyll biosynthesis, transformation, and degradation, thereby enhancing the chlorophyll cycle. Furthermore, the BR treatment significantly increased the number of grana lamellae in the mesophyll cells, which enhanced the biosynthesis of chloroplasts. The increase in the chlorophyll content improved the capture of light energy, electron transport in photosynthesis, and the biosynthesis and metabolism of carbohydrates in the leaves of V. angularis under Cd stress. Full article