Search Results (108)

This study aims to investigate the role of exogenous spermidine (Spd) in mitigating the adverse effects of cadmium (Cd) stress on the growth and development of cucumber (Cucumis sativus). The cucumber cultivar “Xintaimici” was used as the experimental material, and a hydroponic experiment was carried out. Based on a baseline Cd concentration of 10 mg·L⁻¹, Spd was supplemented at concentrations of 0.05, 0.1, 0.2, 0.4, and 0.5 mM, resulting in seven treatment groups: control group (CK), S0 group (Cd-only treatment, 10 mg·L⁻¹ Cd + 0 mM Spd), S1+ Cd group (10 mg·L⁻¹ Cd + 0.05 mM Spd), S2+ Cd group (10 mg·L⁻¹ Cd + 0.1 mM Spd), S3+ Cd group (10 mg·L⁻¹ Cd + 0.2 mM Spd), S4+ Cd group (10 mg·L⁻¹ Cd + 0.4 mM Spd), and S5+ Cd group (10 mg·L⁻¹ Cd + 0.5 mM Spd). This study analyzed the regulatory effects of Spd on the growth and development, antioxidant capacity and cadmium accumulation characteristics of cucumber seeds and seedlings. It was found that cadmium stress significantly inhibited their growth process and led to a decline in multiple physiological indicators. Under a Cd concentration of 10 mg·L⁻¹, the application of 0.2 mM Spd significantly improved these parameters. During the seedling stage, the application of 0.2 mM Spd under Cd stress significantly enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), as well as the content of soluble proteins, while significantly reducing malondialdehyde (MDA) levels. Cd content analysis revealed that 0.2 mM Spd promoted Cd accumulation in roots while suppressing its translocation to young leaves, thereby reducing Cd accumulation in aboveground tissues. Gene expression analysis demonstrated that this treatment significantly upregulated the expression levels of the phytochelatin synthase gene (CsPCS1) and the gene associated with reduced glutathione synthesis (CsGSHS). In conclusion, the exogenous application of 0.2 mM Spd effectively alleviates oxidative damage and osmotic stress induced by Cd stress in cucumber, promotes plant growth, and significantly enhances Cd tolerance. Full article

Cadmium and arsenic co-contamination found in mining actions indicates major effluence in adjacent farmland soils, disturbing the plant physiology and soil’s microbial community. Phosphorus (P) plays a vital role in reducing soil contamination from Cd and As bioavailability and uptake by plants. However, the right P sources for remediation approaches are critical and still require further research in Cd- and As-contaminated soil. This study aimed to explore the effects of different phosphorus fertilizer sources on Lolium perenne growth and its physiological and rhizosphere microbial diversity under combined contamination with Cd and As. Pot experiments were performed with seven treatments including SSP (single super phosphate), DAP (diammonium phosphate), MAP (monoammonium phosphate), CaP (calcium phosphate), HighCaP (high calcium phosphate), RP (rock phosphate), and no phosphorus fertilizer application (CK) with five replications in the RCB design. The SSP treatment showed the greatest plant height (15.7 cm), hay yield (3567.6 kg·ha⁻¹), and enhanced antioxidant defense activities. It also achieved the highest phosphorus accumulation rate (0.63 g·kg⁻¹) with reduced Cd and As uptake. In addition, SSP promoted higher non-protein sulfhydryl (NPT) and phytochelatin synthetase (PCs) contents along with γ-glutamylcysteine synthetase (γ-ECS) activity, and enriched the rhizosphere microbial community, where the Sphingomonas abundance was 7.08% higher than for other treatments. Therefore, this result indicates that SSP can improve the yield and physiology in L. perenne, as well as soil the rhizosphere microbial community structure, while reducing Cd and As accumulation in plants under Cd and As stress. Full article

Cadmium (Cd) is a toxic metal that affects living organisms even at low concentrations, causing physiological alterations and biomass reduction in plants. Arbuscular mycorrhizal fungi (AMF) represent a biological strategy that increases tolerance to heavy metals, although their specific mechanisms in sugarcane remain poorly understood. To address this knowledge gap, an open-field experiment was conducted to evaluate the effects of AMF on Cd accumulation, oxidative stress, photosynthetic pigments, enzymatic antioxidant system, and non-enzymatic antioxidant compounds in sugarcane variety CC 01-1940, using a randomized block design. Results showed that AMF established symbiosis with plants, retaining Cd in the roots and reducing its translocation to leaves. Additionally, they decreased Cd-induced oxidative stress by reducing lipid peroxidation (MDA) and proline content. Although an initial decrease in photosynthetic capacity was observed, AMF helped maintain stable levels of photosynthetic pigments, preserving photosynthetic efficiency. They also activated antioxidant enzymes and increased antioxidant compounds such as reduced glutathione (GSH), non-protein thiols (NP-SH), ascorbic acid (AA), and phytochelatins (PC). These findings demonstrate that symbiosis with AMF protects sugarcane plants from cellular oxidative damage and reduces Cd concentrations in leaves. Therefore, the use of AMF represents an effective strategy to improve the antioxidant defense and resistance of sugarcane plants to cadmium stress. Full article

Arsenic (As) contamination has significantly increased in recent decades due to anthropogenic activities. This is a serious challenge for human health, environmental quality, and crop productivity. Biochar (BC) is an important practice used globally to remediate polluted soils. Likewise, melatonin (MT) has also shown tremendous results in mitigating metal toxicity and improving crop productivity. Nevertheless, the mechanism of combined BC and MT in alleviating As toxicity in rice (Oryza sativa L.) remains unexplored. In this study, we investigated how As affected rice and how the combined BC and MT facilitated As tolerance. The study comprised a control, As stress (100 mg kg⁻¹), As stress (100 mg kg⁻¹) + BC (2%), As stress (100 mg kg⁻¹) + MT (100 µM) and As stress (100 mg kg⁻¹) + BC (2%) + MT (100 µM). Arsenic significantly decreased rice growth and yield by increasing electrolyte leakage (EL), malondialdehyde (MDA), and hydrogen peroxide (H₂O₂). Co-applying BC and MT substantially enhanced rice growth and yield by increasing chlorophyll synthesis (48.12–92.42%) leaf water contents (40%), antioxidant activities (ascorbate peroxide: 56.43%, catalase: 55.14%, peroxidase: 57.77% and superoxide dismutase: 57.52%), proline synthesis (41.35%), MT synthesis (91.53%), and phytochelatins synthesis (125%) nutrient accumulation in rice seedlings and soil nutrient availability. The increased rice yield with BC + MT was also linked with reduced H₂O₂ production, As accumulation, soil As availability, and an increase in OsAPx6, OsCAT, OsPOD, OsSOD OsASMT1, and OsASMT2 and a decrease in expression of OsABCC1. Biochar + MT enhanced residual OM- and Fe, ((Fe₂As) and Mn (Mn₃(AsO₄)₂) bound forms of As leading to a substantial increase in rice growth and yield. Thus, the combination of BC and MT is an eco-friendly approach to mitigate As toxicity and improve rice productivity. Full article

Air pollution acts as a pervasive oxidative stressor, disrupting global crop production and ecosystem health through the overproduction of reactive oxygen species (ROS). Hazardous pollutants impair critical physiological processes—photosynthesis, respiration, and nutrient uptake—triggering oxidative damage and yield losses. This review synthesizes current knowledge on plant defense mechanisms, emphasizing the integration of enzymatic (SOD, POD, CAT, APX, GPX, GR) and non-enzymatic (polyphenols, glutathione, ascorbate, phytochelatins) antioxidant systems to scavenge ROS and maintain redox homeostasis. We highlight the pivotal roles of transcription factors (MYB, WRKY, NAC) in orchestrating stress-responsive gene networks, alongside MAPK and phytohormone signaling (salicylic acid, jasmonic acid, ethylene), in mitigating oxidative stress. Secondary metabolites (flavonoids, lignin, terpenoids) are examined as biochemical shields against ROS and pollutant toxicity, with evidence from transcriptomic and metabolomic studies revealing their biosynthetic regulation. Furthermore, we explore biotechnological strategies to enhance antioxidant capacity, including overexpression of ROS-scavenging genes (e.g., TaCAT3) and engineering of phenolic pathways. By addressing gaps in understanding combined stress responses, this review provides a roadmap for developing resilient crops through antioxidant-focused interventions, ensuring sustainability in polluted environments. Full article

Cadmium (Cd) pollution in rice and selenium (Se) deficiency in humans have attracted widespread attention. In this study, we investigated the effects of the combined application of biological nanoselenium (B-SeNPs) foliar spray and biochar (BC) on Se enrichment and Cd content reduction in rice. A pot experiment was established by designing four levels each of BC and B-SeNPs to be applied to rice plants. The results revealed that soil Cd bioavailability decreased by 3.26–16.67%, while soil Se bioavailability increased by 0.76–7.63% in the combined BC and B-SeNPs treatments, with rice photosynthesis showing significant enhancement during each growth period. Both BC and B-SeNPs treatments significantly enhanced the levels of antioxidant components (glutathione, phytochelatins, catalase, peroxidase, and superoxide dismutase) while reducing oxidative stress markers (malondialdehyde and superoxide anion radical) in rice leaves. Additionally, these treatments effectively modulated the subcellular distribution of Se and Cd, demonstrating their potential in alleviating Cd toxicity and enhancing Se homeostasis. These changes were accompanied by a marked reduction in lipid peroxidation (indicated by malondialdehyde) and superoxide radical accumulation, suggesting that BC and B-SeNPs treatments strengthened the antioxidative defense system in rice leaves. Additionally, compared with the BC0Se0 treatment, the combined application of BC and B-SeNPs significantly enhanced grain Se content by 7.14–221.43% while significantly reducing Cd content by 30.77–76.92%. The efficacy of grain Se enrichment and Cd reduction followed the sequence B-SeNPs + BC > Se only > BC only, where the BC5Se20 treatment demonstrated the most pronounced effects on both Se accumulation and Cd decrease in grains. Therefore, the combined application of foliar-applied B-SeNPs and biochar not only reduces Cd bioavailability in soil but also effectively suppresses Cd uptake by rice while simultaneously enhancing Se enrichment. Full article

Phytochelatins (PCs) are well-characterized for their role in detoxifying non-essential metals like cadmium (Cd), but their role in zinc (Zn) homeostasis remains underexplored. In this study, we investigated the role of the Nicotiana tabacum phytochelatin synthase 1 (NtPCS1) in counteracting Zn toxicity in plants. qRT-PCR data showed that the transcript level of the NtPCS1 gene was upregulated by ZnSO₄, leading to increased PC production in the wild-type tobacco plants. Functional complementation assays in Arabidopsis thaliana revealed that overexpression of NtPCS1 rescued the Zn hypersensitivity of the Atpcs1 mutant, with the N-terminal region being indispensable for Zn tolerance. In addition, transgenic tobacco plants overexpressing NtPCS1 (PCS1 lines) exhibited superior root elongation under ZnSO₄ stress compared to the wild-type plants, particularly when supplemented with glutathione (GSH). The observed phenotypic advantage is attributed to NtPCS1-mediated overproduction of PCs, which facilitated Zn chelation and enabled cellular detoxification. These findings highlight the important role of NtPCS1 in Zn tolerance via GSH-linked PCs synthesis, offering insights into PCS-mediated Zn detoxification and a genetic strategy for developing Zn-resistant plants. Full article

Among the highly toxic heavy metals, cadmium (Cd) is highlighted as a persistent environmental pollutant, posing serious threats to plants and broader ecological systems. Phytochelatins (PCs), which are synthesized by phytochelatin synthase (PCS), are peptides that play a central role in Cd mitigation through metal chelation and vacuolar sequestration upon formation of Cd-PC complexes. PC synthesis interacts with other cellular mechanisms to shape detoxification outcomes, broadening the functional scope of PCs beyond classical stress responses. Plant Cd-related processes have has been extensively investigated within this context. This perspective article presents key highlights of the panorama concerning strategies targeting the PC pathway and PC synthesis to manipulate Cd-exposed plants. It discusses multiple advances on the topic related to genetic manipulation, including the use of mutants and transgenics, which also covers gene overexpression, PCS-deficient and PCS-overexpressing plants, and synthetic PC analogs. A complementary bibliometric analysis reveals emerging trends and reinforces the need for interdisciplinary integration and precision in genetic engineering. Future directions include the design of multigene circuits and grafting-based innovations to optimize Cd sequestration and regulate its accumulation in plant tissues, supporting both phytoremediation efforts and food safety in contaminated agricultural environments. Full article

Heavy metals such as Cu and Cd are important pollutants. Quillay (Quillaja saponaria) is a tree species endemic to Chile that is of worldwide commercial interest due to its saponins. It can grow on contaminated sites. However, the biological mechanisms underlying its defensive responses remain elusive. This study aimed to characterize Quillay plants under Cu and Cd stress and identify mechanisms controlling their interaction with these metals. We subjected six-month-old plants to Cu (75, 150, and 300 μM) and Cd (20, 40, and 80 μM) in hydroponics for a week and assessed growth, metal accumulation, saponin production, and the expression of a suite of stress-induced genes. Those genes are related to phytochelatins (PCS) and metallothioneins (MT), the antioxidant system (GS and GR), and metal transporters (COPT1). The results indicated that both metals were accumulated mainly in roots, with 339.9 and 433.8 mg/kg DW, for Cd and Cu, respectively, exhibiting a metal excluder pattern. Cd increased the length of the principal root. Higher doses of Cd and Cu augmented the saponin content (62.8% and 41.2% compared to control, respectively). The genes GS, GR, and COPT1 modified their transcriptional levels depending on the metal and organ evaluated. These results provide evidence of specific defensive responses of this species against heavy metal stress, which is helpful to guide new research efforts and support the development of strategies for using Quillay for phytoremediation. Full article

It remains an open question whether violets use universal mechanisms, such as the production of metallothioneins, phytochelatins, and organic acids and/or rely on specific mechanisms like the production of antimicrobial cyclic peptides (cyclotides) for heavy metal tolerance. To contribute to the understanding of the role of cyclotides, we used seed-derived plants from metallicolous (M) and non-metallicolous (NM) populations of Viola tricolor, a pseudometallophyte tolerant to Zn and Pb. Eight- to ten-week-old plants were treated with 1000 μM of Zn or Pb for 3 or 7 days and subsequently measured for cyclotides and heavy metal content using MALDI-MS and Atomic Absorption Spectrometry (AAS), respectively. Individuals from the M population accumulated a similar amount of Zn but occasionally more Pb in comparison with the NM population. Of the 18 different cyclotides included in the analysis, some showed statistically significant changes under the heavy metal treatment. In general, a decrease was observed in the M population, whereas an increase was observed in the NM population (except for the 3-day treatment with Zn). The day of treatment and dose of metal and their interaction played a crucial role in the explained variance for cyclotides produced by the M individuals but not for the NM plants. This unravels the importance of this antimicrobial compound in heavy metal tolerance and indicates that, in V. tricolor, cyclotides are involved in heavy metal tolerance, but specimens from two populations have developed different strategies and tolerance mechanisms involving cyclotides to mitigate heavy metal stress. Full article

Melatonin (MT) and brassinolide (BL) are phytohormones that regulate various physiological processes in plants. This study investigates their effects on Wolffia arrhiza when exposed to cadmium (Cd). Plant hormones were quantified using liquid chromatography-mass spectrometry, while photosynthetic pigments and phytochelatins (PCs) were analyzed through high-performance liquid chromatography. Protein, monosaccharide levels, and antioxidant activities were also spectrophotometrically measured. The findings reveal that MT and BL treatment decreased Cd accumulation in W. arrhiza compared to plants only exposed to Cd. MT was particularly effective in reversing Cd-induced growth inhibition and reducing stress markers more significantly than BL. It also enhanced antioxidant activity and maintained higher levels of photosynthetic pigments, proteins, and sugars. Although BL was less effective in these aspects, it promoted greater synthesis of glutathione and PCs in Cd-exposed duckweed. Overall, both MT and BL alleviate the negative impact of Cd on W. arrhiza, confirming their crucial role in supporting plant health under metal stress conditions. Full article

Tomato (Solanum lycopersicum), which is considered one of the more important and widely cultivated crop members of the family Solanaceae, exhibits numerous biochemical mechanisms to alleviate the stress produced by various biotic and abiotic factors. Many researchers have found that phytochelatins (PCs) play an important role in these stress-alleviating mechanisms and, therefore, contribute significantly to the plant’s coping strategies, particularly under heavy metal exposure. Ongoing research has extensively investigated tomato genotypes in plant stress research, with a particular focus on heavy metal stress. The production of PCs, synthesized from glutathione, is regulated by various factors and different stressors. Here, we aim to provide an overview of the panorama regarding the synthesis of PCs in tomato under different environmental conditions and experimental settings, as well as provide information on their broader roles in biotechnology and modulating plant tolerance and responses across diverse stress conditions and treatments within the context of tomato research. Full article

Metallothioneins (MTs) and phytochelatins (PCs) are small Cys-rich proteins with low molecular mass responsible for detoxifying heavy metals in cells. Arabidopsis thaliana expresses eight metallothionein genes and two types of PCS; however, there is still a need to acquire more knowledge regarding their individual responses to some heavy metals. Thus, it was intended to study the expression of AtMT- and AtPCS1-encoding genes in response to high levels of nickel in wild-type A. thaliana. Seeds of A. thaliana were placed in MS medium supplemented with increasing concentrations of Ni—0 mg L⁻¹, 2.5 mg L⁻¹, 5 mg L⁻¹, 7.5 mg L⁻¹, and 10 mg L⁻¹. After 21 days of exposure, the expression of the AtMTs (1A, 1B, 1C, 2A, 2B, and 3) and AtPCS1 was analysed through RT-qPCR in different plant organs: roots, young leaves, and mature leaves. The concentrations of photosynthetic pigments, hydrogen peroxide, and reduced glutathione were also evaluated, but no significant changes were observed. The gene expression analysis showed that the seven genes reacted differentially to the varying concentrations of Ni and in an organ-specific way. It was noted that in roots, the expression of AtMT1A, AtMT1C, and AtMT3 increased starting with the 2.5 mg L⁻¹ treatment. At the same time, the response in the leaves fluctuated more as AtMT1B and AtMT1C increased in young leaves with concentrations higher than 7.5 and 2.5 mg L⁻¹, respectively, with the remaining genes analysed having their expressions decreased starting with 7.5 mg L⁻¹ of Ni. In mature leaves, AtMT1A increased, while AtMT2A, AtMT2B, and AtPCS1 decreased with Ni concentrations starting from 7.5 mg L⁻¹. These results strongly suggest that the increase in the expression of AtMT1B, AtMT1C, and AtMT3 in the roots significantly reduced Ni toxicity, contributing to its local accumulation and buffering its translocation to the shoots. The overall reduction in the expression of MTs and PCS1 in leaves may be linked to the active participation of MT1A in mature leaves, while young leaves depended on the increased production of MT1B and MT1C to deal with the high amount of Ni present therein. These results contribute further knowledge to the understanding of the defence mechanisms of plants against high levels of Ni regarding the participation of MTs and PCS1. Full article

Soil contamination by trace metal elements, such as aluminum and barium, presents specific environmental risks, particularly to plant health and agricultural productivity. Excessive accumulation of these toxic elements in plant tissues can alter redox equilibrium and affect homeostasis. This study sought to examine the physiological reactions of Abelmoschus esculentus (L.) under aluminum- and barium-induced stress. The plants were exposed to multiple concentrations of Al or Ba (0, 100, 200, 400 and 600 µM) for 45 days; then, the accumulation potential of Al and Ba, oxidative damage, and antioxidative metabolism were assessed. Key findings showed a proportional distribution of the Al and Ba in roots and aerial parts of the plants, with lower accumulation in the fruits. The occurrence of oxidative damage and the involvement of antioxidant enzymes were demonstrated by increased amounts of malondialdehyde and H₂O₂, enhanced activity of superoxide dismutase, and decreased catalase activity. The study also highlighted that GSH played a primary role in Al detoxification in the roots and fruits, while phytochelatins were more active in Ba-treated plants, particularly in roots and shoots, facilitating Ba sequestration. Full article

This study investigated the potential of biogenic ZnO nanoparticles (ZnO-NPs) to alleviate cadmium (Cd) toxicity in durum wheat plants exposed for 14 days to 25 μM CdSO₄. By applying ZnO-NPs at two different concentrations (25 and 50 mg L⁻¹), we observed increased chlorophyll content, beneficially impacting the photosynthetic efficiency, and enhanced sulfur, zinc, and iron accumulation. Moreover, the ZnO-NP treatment reduced the Cd accumulation in shoots, mitigating leaf chlorosis and oxidative damage. This response was clearly mediated by the increased thiol and phytochelatin production, as well as the enhanced sulfate uptake rate, with TdSultr1.3 as the most responsive gene coding for high-affinity transporter to Cd stress. In conclusion, the application of biogenic ZnO-NPs appears to be a promising approach for reducing the uptake of heavy metals by plants. In addition, it could be successfully used in combination with contamination prevention measures and/or remediation of contaminated sites to remove and mitigate the harmful effects of Cd on the environment and human health. Full article