Arsenic (As) contamination in soil presents significant challenges to plant growth and development, impacting agricultural productivity, food safety, ecosystem stability, and human health. This study investigates the effects of As toxicity on the medicinal plant Ocimum basilicum L. cultivar CIM-Saumya by assessing the impact of varying As concentrations (1, 5, 10, and 25 mg kg-1 of soil) on various physio-biochemical and microscopic parameters. Controlled experiments were conducted to assess the photosynthetic rate, gas exchange, and the activities of carbonic anhydrase (CA), Rubisco, and nitrate reductase (NR) enzymes. In addition, the concentrations of non-enzymatic antioxidants (proline, flavonoids, and phenolic compounds) and enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX) were analyzed. Alterations in glandular trichomes, essential oil (EO) content, and composition were also evaluated. Confocal laser scanning microscopy (CLSM) was utilized to examine root cell viability and detect reactive oxygen species (ROS). Our results revealed that As exposure significantly inhibited physio-biochemical activities in O. basilicum, with low As concentrations (1 mg kg-1) enhancing EO content by 18.75 %. However, higher As concentrations (25 mg kg-1) induced oxidative stress, evidenced by increased malondialdehyde (MDA), ROS accumulation, reduced trichome size and density, and smaller stomatal apertures. The highest As concentration resulted in a 53.12 % reduction in EO content. These findings demonstrate that O. basilicum exhibits differential responses to As stress, with low concentrations enhancing EO production, while high concentrations cause oxidative damage and reduced EO content, providing insights into the plant's adaptive strategies and potential alterations in its aroma and therapeutic properties under As stress.

Soil cadmium (Cd) contamination threatens plant growth and agricultural productivity. Hibiscus syriacus L., valued for its ornamental, edible, and medicinal properties, is widely cultivated in Cd-contaminated areas of southern China.This study aimed to evaluate the effectiveness of nano-zinc oxide (nZnO) in alleviating Cd toxicity in H. syriacus, examining plant phenotypes, physiological and biochemical responses, root ultrastructure, and the accumulation and distribution of Cd and Zn within the soil-H. syriacus system. Pot experiments included Cd treatment (100 mg/kg) and combined soil or foliar applications of nZnO (50 and 100 mg/L), with plants harvested after 45 days. Compared to Cd treatment alone, the combined application of nZnO significantly increased biomass in roots, stems, and leaves, improved photosynthetic performance, osmotic regulation, and antioxidant levels, and mitigated root cell damage; Cd concentrated mainly in roots, and nZnO reduced root Cd levels by 0.24 %-9.06 %. SEM-EDS observations revealed that Cd predominantly accumulated in the root epidermis and cortex, with Cd stress leading to increased levels and localized aggregation of Cd in the xylem. By contrast, nZnO treatment alleviated this disruption. Leaf application of 50 mg/L nZnO showed the best results. These findings highlight nZnO as a promising nano fertilizer for alleviating Cd stress in plants.

Mitigating the co-existence of environmental stresses on crop plants necessitates the development of integrated, eco-friendly, and sustainable approaches to alleviate plant stress responses. This study represents the first attempt to mitigate the toxic impact of prevalent pollutant (salinity) and an emergent plastic manufacturing pollutants (bisphenol A, BPA) using the polyamine (cadaverine).Tomato plants, treated with or without cadaverine, were subjected to NaCl salinity (120 mM), BPA (375 mg kg(-1) soil), and their combinations compared to non-stressed control plants examining morphological, physiological, metabolic, and molecular responses. After 10 days of transplanting, tomato plants under combined stress were unable to survive without cadaverine application. However, cadaverine spraying mitigated the damaging effects of both single and combined stresses under short- and long-term exposure, enabling stressed plants to endure the conditions and complete their life cycles. Cadaverine efficiently restrained the reduction in chlorophylls, carotenoids, and cytosolutes under applied stresses compared to the stressed plants. Cadaverine also increased alpha-tocopherol content (by 171 and 53 %) and enhanced the activity of polyphenol oxidase (by 26 and 32 %), glutathione s-transferases (by 18 and 39 %), superoxide dismutase (by 23 and 46 %), and phenylalanine ammonia-lyase (by 9 and 25 %), under BPA and salinity stress, respectively. Thus, cadaverine ameliorated the oxidative and nitrosative burst induced by BPA or salinity, respectively by declining hydroxyl radical (by 28 % and 20 %), superoxide anion (by 73 % and 74 %), nitric oxide (by 60 and 65 %), lipid peroxidation (by 35 % and 54 %), and lipoxygenase activity (by 74 and 68 %). Moreover, cadaverine enhanced the expression of defence-related genes, including polyphenol oxidase, tubulin, and thaumatin-like protein, and reduced the uptake of BPA in the tomato's roots while promoting its metabolism in leaves and fruits. This ensured the safety of the harvested fruits. By mitigating stress, improving plant resilience, and limiting pollutant accumulation, cadaverine presents significant potential for sustainable agricultural practices and food safety. These findings offer valuable insights into the role of cadaverine in managing abiotic stress and safeguarding crop health in environmentally challenging conditions.

Soil salinity is a severe abiotic stress that damages plant growth and development. As an antioxidant and free radical scavenger, melatonin is well known for helping plants survive abiotic conditions, including salinity stress. Here, we report that the salt-related gene MsSNAT1, encoding a rate-limiting melatonin biosynthesis enzyme, is located in the chloroplast and contributes to salinity stress tolerance in alfalfa. We found that the MsSNAT1 overexpressing alfalfa lines exhibited higher endogenous melatonin levels and increased tolerance to salt stress by promoting antioxidant systems and improving ion homeostasis. Furthermore, through a combination of transcriptome sequencing, dual-luciferase assays and transgenic analysis, we identified that the basic leucine zipper (bZIP) transcription factor, MsbZIP55, is associated with salt response and MsSNAT1 expression. EMSA analysis and ChIP-qPCR uncovered that MsbZIP55 can recognize and directly bind to the MsSNAT1 promoter in vitro and in vivo. MsbZIP55 acts as a negative regulator of MsSNAT1 expression, thereby reducing melatonin biosynthesis. Morphological analysis revealed that overexpressing MsbZIP55 conferred salt sensitivity to transgenic alfalfa through a higher Na+/K+ ratio and lower antioxidant activities, which could be alleviated by applying exogenous melatonin. Silencing of MsbZIP55 by RNA interference in alfalfa resulted in higher expression of MsSNAT1 and promoted salt tolerance by enhancing the antioxidant system enzyme activities and ion homeostasis. Our findings indicate that the MsbZIP55-MsSNAT1 module plays a crucial role in regulating melatonin biosynthesis in alfalfa while facilitating protection against salinity stress. These results shed light on the regulatory mechanism of melatonin biosynthesis related to the salinity stress response in alfalfa.

Addressing saline soil issues while ensuring agricultural productivity requires innovative technologies. This study investigated the impact of adding an innovative remediation preparation, specifically leguminous compost containing 50 g (LCT+CS-1), 100 g (LCT+CS-2), or 150 g of corn silk kg-1 (LCT+CS-3), to saline soil (ECe = 11.05 dS m-1) on soil characteristics and fenugreek plant performance during the 2022/2023 and 2023/2024 seasons. All organic supplementations significantly improved soil organic matter content, nutrient levels, and enzyme activities (urease, acid and alkaline phosphatase, and catalase) while reducing soil pH and Na+ content compared to the control. These results reflected decreased Na+ content, oxidative stress indicators (hydrogen peroxide and superoxide radicals), and oxidative damage (leaf electrolyte leakage and malondialdehyde levels) in fenugreek plants. On the other hand, leaf integrity (chlorophyll and carotenoid contents, membrane stability index, and relative water content) and nutrient contents improved. Furthermore, K+/Na+ ratio, osmoregulatory compounds (soluble sugars and proline), antioxidant levels (glutathione, ascorbate, phenols, and flavonoids), and antioxidant activity increased notably. Thus, notable increases in plant growth and yield traits and seed quality (trigonelline, nicotinic acid, total phenols, and flavonoids) were achieved. LCT+CS-2 was the most effective treatment for saline soil (ECe = 11.05 dS m-1), alleviating salinity effects and improving fenugreek growth, yield, and seed quality traits.

Soil contamination with arsenic (As) is becoming a serious concern for living organisms. Arsenic is a nonessential metalloid for plants, humans, and other living organisms. Biochar (BC) is a very effective amendment to remediate polluted soils and it received great attention owing to its appreciable results. Arsenic toxicity negatively affects plant morph-physiological and biochemical functioning and upsurges the generation of reactive oxygen species (ROS), which negatively affect cellular structures. Arsenic toxicity also reduces seed germination and impedes plant growth by decreasing nutrient uptake, causing oxidative damage and disrupting the photosynthetic efficiency. Plants use different strategies like antioxidant defense and increased osmolyte synthesis to counteract As toxicity; nevertheless, this is not enough to counter the toxic impacts of As. Thus, applying BC has shown tremendous potential to counteract the As toxicity. Biochar application to As-polluted soils improves water uptake, maintains membrane stability and nutrient homeostasis, and increases osmolyte synthesis, gene expression, and antioxidant activities, leading to better plant performance. Additionally, BC modulates soil pH, increases nutrient availability, causes As immobilization, decreases its uptake and accumulation in plant tissues, and ensures safer production. The present review describes the sources, toxic impacts of As, and ways to lower As in the environment to decrease its toxic impacts on humans, the ecosystem, and the food chain. It concentrates on different mechanisms mediated by BC to alleviate As toxicity and remediate As-polluted soils and different research gaps that must be fulfilled in the future. Therefore, the current review will help to develop innovative strategies to minimize As uptake and accumulation and remediate As-polluted soils to reduce their impacts on humans and the environment.

Antimony (Sb) pollution is becoming more prevalent due to human activities. Recently, biochar (BC) and modified biochar have been used to remediate polluted soils. Nevertheless, role of modified BC and microbes to mitigate adversities of Sb is not understood. This study evaluated the effects of iron-modified biochar (FMB) and bacteria (Ochrobactrum oryzae) on rice plant functioning, Sb bio-accessibility, and microbial community structure and diversity. The experiment consisted of different treatments; control, Sb stress (1200 mg kg-1), Sb stress (1200 mg kg-1) + FMB (2.5 %), Sb stress (1200 mg kg-1) + bacterial inoculation and Sb stress (1200 mg kg-1) + FMB (2.5 %) + bacterial inoculation. The combined FMB and bacteria increased photosynthetic pigments, antioxidant activities, osmolyte accumulation and reduced oxidative damage, electrolyte leakage (EL), and malondialdehyde (MDA), thereby leading to better growth and yield. Combined FMB and bacterial inoculation also enhanced soil nutrient availability, soil organic carbon (SOC), and soil enzymatic activities thereby reducing the soil antimony availability (46.12 %) and bio-accessibility of Sb (Sb-bio: 59.25 %). Moreover, co-applying BC and bacteria inoculation reduced Sb accumulation rice roots and grains which was associated with increased soil pH, SOC, and soil enzyme activity. Additionally, FMB and bacteria application increased the abundance of favorable bacteria including Proteobacteria, Gemmatimonadete, Firmicutes, Bacteroidota, Chloroflexi, Myxococcota and Parcubacteria which also helped to counteract the toxic impacts of Sb. Therefore, the combination of FMB and bacteria can increase rice production in Sb-polluted soils. These findings offer a way to develop environmentally friendly technologies to improve safer and sustainable rice production in Sb-contaminated soils.

Contamination of vegetables with heavy metals and microplastics is a major environmental and human health concern. This study investigated the role of taurine (TAE) in alleviating arsenic (As) and polyvinyl chloride microplastic (MP) toxicity in broccoli plants. The experiment followed a completely randomized design with four replicates per treatment. Plants were grown in soil spiked with MP (200 mg kg-1), As (42.8 mg kg-1), and their combination (As + MP) with or without taurine (TAE; 100 mg L-1) foliar supplementation. Results demonstrated that MP, As, and As + MP toxicity markedly decreased growth, chlorophyll content, photosynthesis, and nutrient uptake in broccoli plants. Exposure to individual or combined MP and As increased oxidative damage, indicated by elevated methylglyoxal (MG), superoxide radical (O2 & sdot;-), hydrogen peroxide (H2O2), hydroxyl radical (& sdot;OH), and malondialdehyde (MDA) levels alongside intensified lipoxygenase (LOX) activity and leaf relative membrane permeability (RMP). Histochemical analyses revealed higher lipid peroxidation, membrane damage as well as increased H2O2 and O2 center dot- levels in the leaves of stressed plants. Micropalstic and As toxicity deteriorated anatomical structures, with diminished leaf and root epidermal thickness, cortex thickness, and vascular bundle area. However, TAE improved the antioxidant enzyme activities, endogenous ascorbate-glutathione pools, hydrogen sulfide and nitric oxide levels that reduced H2O2, O2 & sdot;-, & sdot;OH, RMP, MDA, and activity of LOX. Taurine elevated osmolyte accumulation that protected membrane integrity, resulting in increased leaf relative water content and plant biomass. Plants supplemented with TAE demonstrated improved anatomical structures, resulting in diminished As uptake and its associated phytotoxicity. These findings highlight that TAE improved redox balance, osmoregulation, ion homeostasis, and anatomical structures, augmenting tolerance to As and MP toxicity in broccoli.

Cadmium (Cd) is a widespread and strongly toxic environmental pollutant. In this study, the interaction between Cd and essential nutritional metals, such as iron (Fe) and zinc (Zn), was investigated in banana plants (Musa spp. cultivar Grand Nain), cultured in vitro, using Fourier-transform infrared (FT-IR) and physiological analysis. Plantlets were treated in vitro with Fe and Zn (200 and 500 mg/L) under 500 mg/L Cd exposure. The results showed that Cd toxicity increased Cd uptake and raised % of damage. However, Fe and Zn addition ameliorated the negative impact of Cd stress by reducing Cd and enhancing Fe, Zn, P, and K contents. The FT-IR analysis showed alterations within the bands correlated to the foremost macromolecules in plants under Cd stress and its interactions with Fe or Zn. The peaks of some functional groups at 3381.7 cm-1 for carbohydrates, proteins, alcohols, and phenolic compounds, 2922.02 cm-1 for lipids, 1643.97 cm-1 for amide I, 1517.46 cm-1 for amide II, 1057.63 cm-1 for cellulose and hemicellulose, and 616.94 cm-1 for aromatic compounds were negatively shifted by Cd stress. However, Fe and Zn regulated transmittance and intensity of these bands, showing improved tolerance to Cd. Moreover, Fe and Zn modulated the total antioxidants and enzymatic antioxidant activities for catalase and ascorbate peroxidase. The study concluded that the nutrition with Fe and Zn enhanced banana tolerance against Cd toxicity. It also highlighted the powerful role of FT-IR in understanding the mechanisms involved in minimizing Cd toxicity in banana shoots under Fe and Zn.

Heavy metal (HM) pollution in agricultural soils threatens plant growth and food security, underscoring the urgency for sustainable and eco-friendly solutions. This study investigates the potential of endophytic fungi, Fusarium proliferatum SL3 and Aspergillus terreus MGRF2, in mitigating nickel (Ni) and cadmium (Cd) stress in Solanum lycopersicum (tomato). These fungi were evaluated for their plant growth-promoting traits, including the production of indole-3-acetic acid (IAA) and siderophores, offering a sustainable strategy for alleviating HM toxicity. Inoculation with SL3 and MGRF2 significantly reduced metal accumulation in plant tissues by enhancing metal immobilization and modifying root architecture. Microscopic analysis revealed that fungi protected root epidermal cells from Ni- and Cd-induced damage, preserving cellular integrity and preventing plasmolysis. Fungal-treated plants exhibited improved growth and biomass, with SL3 demonstrating superior Cd stress mitigation and MGRF2 excelling under Ni stress. Photosynthetic pigment levels, including chlorophyll-a and carotenoids, were restored, highlighting the role of fungi in maintaining photosynthetic efficiency. Antioxidant activity was also modulated, as reduced glutathione (GSH) levels and increased flavonoid production were observed, contributing to enhanced oxidative stress management. Hormonal profiling revealed that fungal inoculation balanced stress-induced hormonal disruptions, with lower abscisic acid (ABA) levels and improved salicylic acid (SA) and gibberellic acid (GA) pathways. These changes facilitated better stress adaptation, enhanced nutrient uptake, and improved physiological performance. qRT-PCR analysis further revealed differential gene expression patterns, while antioxidant enzyme activity strengthened the plants' defense against HMinduced oxidative damage. Multivariate analyses highlighted shoot and root traits as critical indicators of resilience, with fungal inoculation driving substantial improvements. These findings demonstrate the potential of SL3 and MGRF2 as eco-friendly bioinoculants, offering a sustainable and cost-effective approach to reducing HMs toxicity in contaminated soils while enhancing crop productivity. This work highlights the promising role of plant-microbe interactions in advancing sustainable agriculture and addressing the challenges posed by heavy metal pollution.