Small organic compounds (SOCs) are widespread environmental pollutants that pose a significant threat to ecosystem health and human well-being. In this study, the FrmA gene from Escherichia coli was overexpressed alone or in combination with FrmB in Arabidopsis thaliana and their resistance to multiple SOCs was investigated. The transgenic plants exhibited varying degrees of increased tolerance to methanol, formic acid, toluene, and phenol, extending beyond the known role of FrmA in formaldehyde metabolism. Biochemical and histochemical analyses showed reduced oxidative damage, especially in the FrmA/BOE lines, as evidenced by lower malondialdehyde (MDA), H2O2 and O-2(center dot-) levels, indicating improved scavenging of reactive oxygen species (ROS). SOC treatment led to significantly higher levels of glutathione (GSH) and, to a lesser extent, ascorbic acid (AsA) in the transgenic plants than in the wild-types. After methanol exposure, GSH levels increased by 95 % and 72 % in the FrmA/BOE and FrmAOE plants, respectively, while showing no significant increase in the wild-type plants. The transgenic plants also maintained higher GSH:GSSG and AsA:DHA ratios, exhibited upregulated glutathione reductase (GR) and dehydroascorbate reductase (DHAR) activities, and correspondingly increased gene expression. In addition, the photosynthetic parameters of the transgenic plants were less affected by SOC stress, which represents a significant photosynthetic advantage. These results emphasize the potential of genetically engineered plants for phytoremediation and crop improvement, as they exhibit increased tolerance to multiple hazardous SOCs. This research lays the foundation for sustainable approaches to combat pollution and improve plant resilience in the face of escalating environmental problems.

Aluminum (Al) toxicity is a major limiting factor for plant growth in acidic soils. Melatonin (MT) is involved in plant responses to various environmental stresses. In this study, the role of exogenous MT in alleviating Al toxicity was investigated in soybean (Glycine max L.). The results demonstrated that MT application alleviated Al-induced inhibition of root elongation, reduced Al accumulation in root tips, and mitigated oxidative damage and cell death in root tips. Under Al stress, MT treatment increased the activities of antioxidant enzymes (SOD, CAT, APX, and POD) and the contents of antioxidants (ASA and GSH) in root tips. Furthermore, Al stress significantly enhanced citrate secretion from soybean roots, while MT application further promoted citrate efflux under Al exposure. Under Al stress, MT treatment significantly increased citric acid levels in root tips by upregulating the expression of citrate synthase gene and downregulating the expression of aconitase gene. In addition, MT application significantly increased the expression of citrate transporter genes (GmMATE13 and GmMATE47) in root tips. Taken together, these findings suggest that MT enhances soybean tolerance to Al stress by activating the antioxidant defense system and promoting citrate secretion. This study provides a theoretical foundation for the application of MT to mitigate Al toxicity in plants.

Introduction Arbuscular mycorrhizal fungi (AMF) show significant potential for improving plant tolerance to vanadium (V) stress. However, the pattern and physiological mechanisms behind this effect are not fully understood.Methods To investigate this, we used green foxtail (Setaria viridis) as a test plant and inoculated this plant with (+AMF) or without (-AMF) Rhizophagus irregularis. These +AMF and -AMF plants were grown in soils with low (150 mg kg-1), medium (500 mg kg-1), and high (1000 mg kg-1) V pollution levels.Results Our results showed root colonization of +AMF plants, whereas no such colonization was observed in -AMF plants. Compared to -AMF plants, +AMF plants showed a more organized arrangement of leaf cells, intact chloroplasts, fewer starch granules, and an intact nuclear membrane. AMF increased leaf chlorophyll a concentration by 49% under high V pollution and that of chlorophyll b by 18% under low V pollution and 36% at medium soil V levels. AMF reduced the concentration of malondialdehyde (MDA) by 36%-40% in leaves and increased the activities of superoxide dismutase (SOD) by 20%-84%, catalase (CAT) by 5%-13%, and peroxidase (POD) by 12%-16%. +AMF plants exhibited 13%-32% greater plant height, 17%-23% longer root length, 42%-78% higher shoot biomass, 61%-73% greater root biomass, 16% increased root-to-shoot ratio (at high V pollution), and 7%-13% elevated leaf phosphorus concentration than -AMF plants. Furthermore, +AMF shoots had 16%-30% lower V concentrations than -AMF plants while +AMF roots exhibited 52%-73% smaller V concentrations than the -AMF control.Discussion These results suggest that AMF increase plant tolerance to V stress by protecting leaf ultrastructure, increasing chlorophyll concentration, reducing oxidative damage as well as biomass-driven V dilution and these effects of AMF were independent of soil V concentrations.

Endocrine-disrupting chemicals (EDCs) are ubiquitous emerging environmental contaminants. However, the comprehensive impact of EDCs on soil ecosystems, particularly on the model organism Eisenia fetida, remains inadequately understood due to disparate experimental and assessment methods. A meta-analysis was conducted to analyze the effects of EDCs on earthworm functional traits, including survival, behavior, growth, reproduction, and cellular responses. The analysis revealed that EDCs significantly impaired earthworm survival (-17.5%, p < 0.05), behavior (- 62.2%, p < 0.001), growth (-11.5%, p < 0.001), and reproduction (- 36.7%, p < 0.001). EDCs induced substantial oxidative stress, evidenced by a 36.5% (p <0.001) increase in reactive oxygen species (ROS) production and elevated oxidative damage. The antioxidant defense system showed compensatory activation, with enhanced superoxide dismutase (10.0%) and catalase (8.90%) activities and glutathione levels (23.3%) (p < 0.001). The present study found chemical-specific toxicity patterns with heavy metals causing the most severe effects on behavior and reproduction. Toxicity profiles varied with exposure concentration and duration, revealing complex dose-response and temporal relationships. These findings provide crucial insights for the ecological risk assessment of EDCs and establish a foundation for developing targeted mitigation strategies. Furthermore, the findings highlight the importance of taking multiple endpoints into account when evaluating the toxicity of EDCs and suggest possible directions for future research.

Copper (Cu) holds a significant importance in plant metabolism as it serves as an essential micronutrient but becomes toxic at higher concentrations. Nitric oxide (NO), a key signaling molecule, and nitrogen (N) play essential roles in combating toxicity of some metals. This study explores the potential of interactive effects of NO as 100 mu M SNP (sodium nitroprusside, NO source) and N (80 mg N kg-1 soil) in mitigating Cu (100 mg Cu kg-1 soil) stress in mustard (Brassica juncea L.) plants. The impaired physio-biochemical changes, photosynthetic efficiency, and the expression level of genes associated with photosynthesis, and N assimilation under Cu stress were ameliorated with the exogenous application of NO and N. The combined treatment of NO and N conspicuously lowered reactive oxygen species (ROS) and its related impacts. It also enhanced the activity and relative expression of antioxidant enzymes, including ascorbate peroxidase (APX), glutathione reductase (GR), and superoxide dismutase (SOD) as well as N assimilation enzymes, such as nitrate reductase (NR) and nitrite reductase (NiR). The supplementation of NO and N also triggered the expression of rbcL (large subunit of Rubisco), photosystem (photosystem II D1 protein; psbA and photosystem II protein B; psbB) and markedly improved photosynthetic capacity under Cu stress. The study highlights the significance of NO and N as a potential strategy to counteract Cu-induced stress in crops. It suggests a synergistic or interactive effect between the two substances as a phytoremediation strategy for enhancing crop growth and productivity in Cu-contaminated soils. Understanding the mechanisms behind NO and N mediated stress alleviation could facilitate the development of targeted approaches to enhance plant resilience against heavy metal stress.

Soil salinization is a severe environmental issue limiting the growth and yield of crops worldwide. Subsurface drip irrigation with micro-nano bubble hydrogen water (SDH) is an innovative way to realize the role of hydrogen gas (H2) in improving plant resistance to salt stress in practical agricultural productions. Nonetheless, limited information is available on how SDH affects the plant salt tolerance performance. Especially, the underlying physiological respond, hormone-regulated and soil microbial-mediated mechanisms have not been reported so far. In this study, the effects of SDH on lettuce (Lactuca sativa L.) growth, photosynthesis, root development, antioxidant system, phytohormone, and soil microbial community were investigated under normal and salt stress conditions. The results showed that, with salt stress, SDH significantly enhanced the lettuce fresh weight, photosynthesis activity, and root growth. The leaf antioxidant enzyme activities increased and reactive oxygen species (ROS) content decreased to reduce the oxidative damage. The decreased malondialdehyde (MDA) content indicated a low membrane lipid peroxidation responsible for cellular damage. SDH also helped to maintain osmotic homeostasis, which was reflected by the increased soluble protein (SP) content. Reduced Na+/ K+ ratio and ROS did not trigger excessive production of stress response hormones abscisic acid (ABA) and jasmonic acid (JA), which alleviated the mediated growth inhibition effects. SDH enriched the abundance of the plant growth-promoting rhizobacteria (PGPR) in the soil, such as Arthrobacter and Pseudomonas. That might be the reason for explaining the increase in hormone indoleacetic acid (IAA) in lettuce and 1-aminocyclopropane-1carboxylate (ACC) deaminase activity in the soil, which was beneficial for inhibiting ethylene production and promoting plant growth. Under the normal condition, variations of physiological and growth indicators as affected by SDH were similar to those under the salt stress condition, except for root development. High concentration of dissolved hydrogen gas in water might expel the oxygen. The induced soil anoxic environment limited oxygen diffusion, in turn inhibited root respiration and growth. The effect of hydrogen concentration on the plant tolerance against salt stress under different salt content could be further studied.

Understanding the mechanisms that give rise to obstacles in the continuous cultivation of C. pilosula is essential for addressing or mitigating these challenges. The findings of this study suggest that repeated cultivation significantly reduced the content of polysaccharide in roots, and significantly increased the dead seedling rate in the field. The vascular bundles of the affected plant were extensively colonized by fungi. Furthermore, the root vascular bundles exhibit significant woodiness and corkiness, accompanied by cellular fractures and structural collapse. It was determined that the pathogenic endophyte is Fusarium oxysporum, and the exacerbated disease manifestation corresponds to an acute wilting type. Additionally, the root-zone soil microorganisms Cladosporium austroafricanum, Fusarium foetens, Fusarium petersiae, and Acaulium retardatum may significantly contribute to the yield-reducing phenomenon associated with continuous cropping. The proliferation of pathogenic bacteria during continuous cultivation initiates a complex interaction mechanism between the host plant and these pathogens. This process is characterized by a rapid increase in calcium ion (Ca2+) concentration, which subsequently leads to an upsurge in reactive oxygen species (ROS), particularly manifested as elevated levels of hydrogen peroxide (H2O2). Additionally, this response triggers thickening of cell walls and other immune mechanisms aimed at inhibiting the invasion of pathogenic bacteria. At the same time, to prevent ROS from inducing oxidative damage and triggering oxidative stress, there is a notable increase in both antioxidant enzyme activity and antioxidant substances content.

Arsenic (As) is a toxic metal that can harm plants by causing oxidative stress, stunting growth, and disrupting metabolism. This study investigates the potential effect of gamma-aminobutyric acid (GABA) and salicylic acid (SA) in mitigating the toxic effects of As on sunflower plants. The aim is to enhance growth, improve metabolite accumulation, strengthen antioxidant defenses, reduce oxidative stress, enhance nutrient status, and minimize As uptake in sunflower plants. To investigate the effect of GABA and SA on arsenic toxicity, two sunflower genotypes (FH-779 and FH-773) were exposed to arsenic at a concentration of 60 mg kg(-)(1) in the soil. The experimental design followed a completely randomized design with three replications of each treatment arranged in a factorial manner. The sunflower plants were treated with foliar sprays of GABA (200 mg L--(1)), SA (100 mg L--(1)), and a combination of both GABA + SA (200 + 100 mg L--(1)). Both FH-779 and FH-773 genotypes exhibited significant accumulation of As + 5 and As+ 3 in roots and leaves, resulting in reduced nutrient uptake. GABA, SA, and GABA + SA treatments alleviated As-induced oxidative stress by reducing hydrogen peroxide (H2O2) production and malondialdehyde (MDA) levels in both genotypes. These treatments also enhanced osmolyte accumulation, improving osmotic adjustment under As stress. Additionally, GABA and SA spray enhanced the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), aiding in scavenging reactive oxygen species (ROS) and preventing oxidative damage. The combination of GABA and SA had a more pronounced effect on the translocation and remediation of As compared to GABA and SA alone. Arsenic removal efficiency reached maximum in the GABA + SA treatment in both FH-779 and FH-773 genotypes, greater than control group, respectively. The findings of this study highlight the beneficial roles of gamma-aminobutyric acid and salicylic acid in mitigating the negative effects of arsenic on growth of sunflower plants. These compounds regulate photosynthetic pigments, osmotic pressure, and antioxidant defense systems, improve nutrient status, and reduce arsenic uptake. Salicylic acid and gamma-aminobutyric acid show potential for alleviating stress in other crops facing abiotic stress. This study highlights the impact of these compounds on plant defense mechanisms in stress conditions, providing a promising approach to reduce arsenic toxicity in crops, thereby improving agricultural productivity in contaminated environments.

Fodder soybean (Glycine max L.) with high protein and yield is a popular forage grass in northeast China. Seasonal drought inhibits its growth and development during seedling stage. The objective of this study was to observe morpho-physiological changes in fodder soybean seedlings under melatonin (MT) treatments and identify appropriate concentration to alleviate the drought damage. Two varieties commonly used in northeast China were treated with 0, 50, 100, and 150 mu M melatonin at soil water content of 30%. The results indicated that applying melatonin enhanced height, biomass and altered root morphology of fodder soybean seedlings under water-deficient conditions. The treatments with melatonin at different concentrations significantly reduced the contents of H2O2, O2- and MDA, while boosting the capacity of the antioxidant defense system and the content of osmotic adjustment substances. Meanwhile, increases in light energy capture and transmission efficiency were observed. Furthermore, treatment with melatonin regulated the expression levels of genes associated with photosynthesis and the antioxidant defense system. Notably, 100 mu M melatonin treatment produced the most favorable effect in all treatments under drought conditions. These research results provide new information for enhancing the drought tolerance of fodder soybean using chemical measures.

Soil cadmium (Cd) pollution is a serious ecological problem worldwide. Understanding Cd-detoxification mechanisms in woody plants will help to evaluate their tolerance ability and phytoremediation potential to Cd-polluted soils. This study investigated the growth, physiochemistry, Cd distribution, and transcriptome sequencing of male and female poplars under three Cd levels (0, 50, and 100 mg & sdot;kg-1). The results showed that Cd stress significantly inhibited the growth of aboveground parts. Over 70 % of the Cd was distributed in the cell wall fraction of roots, stems, and leaves, with the majority accumulating in the roots. Poplars can conjugate Cd with phytochelatins to reduce Cd damage, which is more evident in males than females. The antioxidant defense system of females is more effective than that of males at reducing the damage from Cd. Females demonstrated a stronger Cd-regulation ability than males under the 100 mg & sdot;kg- 1 Cd treatment. Sex-specific responses to Cd were associated with differential gene expression. Under Cd stress, the genes related to oxidation-reduction processes, antioxidant enzyme activity and defense mechanisms, cell wall synthesis, and glutathione metabolism were mainly enriched and upregulated in females, whereas in males, genes related to photosynthesis and photosynthetic pigment biosynthesis were mainly enriched and downregulated, indicating greater damage to the photosynthetic system than in females. Our study provides novel insights into the mechanisms responding to Cd tolerance in poplars. Further studies should be carried out to assess the impact of soil Cd pollution on the wood quality of poplars.