Soil salinization has been the major form of soil degradation under the dual influence of climate change and high-intensity human activities, threatening global agricultural sustainability and food security. High salt concentrations induce osmotic imbalance, ion stress, oxidative damage, and other hazards to plants, resulting in retarded growth, reduced biomass, and even total crop failure. Halo-tolerant plant growth promoting rhizobacteria (HT-PGPR), as a widely distributed group of beneficial soil microorganisms, are emerging as a valuable biological tool for mitigating the toxic effects of high salt concentrations and improve plant growth while remediating degraded saline soil. Here, the current status, harm, and treatment measures of global soil salinization are summarized. The mechanism of salt tolerance and growth promotion induced by HT-PGPR are reviewed. We highlight that advances in multiomics technologies are helpful for exploring the genetic and molecular mechanisms of microbiota centered on HT-PGPR to address the issue of plant losses in saline soil. Future research is urgently needed to comprehensively and robustly determine the interaction mechanism between the root microbiome centered on HT-PGPR and salt-stressed plants via advanced means to maximize the efficacy of HT-PGPR as a microbial agent. Halo-tolerant plant growth promoting rhizobacteria (HT-PGPR) are a valuable biological tool for mitigating the toxic effects of high salt concentrations. And the microbiome centered on HT-PGPR is solutions for sustainable agriculture in saline soils.
(3-Hexachlorocyclohexane ((3-HCH) is a persistent organochlorine pesticide that poses a significant threat to the ecological environment, necessitating the urgent development of effective degradation methods. Microbial degradation has demonstrated substantial potential among various bioremediation techniques due to its environmentally friendly and economical characteristics. This study evaluates the degradation capability of Enterobacter sp. CS01 on (3-HCH, its physiological responses, and its potential application in soil remediation. Under optimal conditions (pH 7, 30 degrees C), 51 % of (3-HCH was effectively removed. Metabolomics and antioxidant enzyme activity analyses revealed that CS01 defends against oxidative damage by modulating the activities of superoxide dismutase (SOD) and catalase (CAT), involving butyrate, alanine, aspartate, and glutamate metabolism, as well as the pentose phosphate pathway. CS01 converts (3-HCH into less toxic intermediates through dichloride elimination, dehalogenation of hydrogen, and hydrolysis reactions. Soil experiments indicated that soil enzyme activities (S-POD, S-DHA, S-PPO) are closely related to the degradation of (3-HCH, with the order of carbon source utilization being esters, amino acids, and sugars. This study provides new insights into the microbial degradation mechanisms of organochlorine pesticides and aids in the development of more efficient and environmentally friendly degradation technologies.
Buried steel gas pipelines are increasingly facing safety challenges due to the escalating traffic loads and varying burial depths, which could potentially lead to hazards such as leakage, fire, and explosion. This paper investigates stress mechanisms in buried steel gas pipelines subjected to vehicular loading through integrated analytical approaches. Theoretical modeling incorporates three key components: dynamic vehicle load characteristics, soil-pipeline interaction pressures, and stress distribution angles across pipeline cross-sections. Stress variations are systematically quantified under varying soil conditions and load configurations. A finite-element model was developed to simulate pipeline responses, with computational results cross-validated against theoretical predictions to establish stress profiles under multiple operational scenarios. Additionally, this paper employ fatigue accumulation damage and reliability theories, utilizing Fe-Safe software to evaluate pipeline reliability, determining fatigue life and strength coefficients for various loads and burial depths. Based on these analyses, this paper develop risk control measures and protective methods for buried steel gas pipelines, validated through finite-element and fatigue analyses. Overall, this paper offers insights for preventing and controlling risks to buried steel gas pipelines under vehicle loads.
Cadmium (Cd) contamination in agricultural soil and accumulation in rice poses serious threat to human health. It is reported that Selenium (Se) can mitigate the toxic effect of Cd in rice. But the underlying mechanism of Se preventing the Cd accumulation and restoring the micronutrient content in rice grains have not been studied before. Therefore, our main aim is to reduce Cd content and restore micronutrient content in rice grain and study the mechanism. Two indigenous rice genotypes (Maharaj and Jamini) were exposed to 10 and 50 mu M Cd in presence and absence of Se (5 mu M) with a control set and assessed for plant growth, biomass, Cd content, ROS and antioxidants for Cd induced toxicity and amelioration. Genes for micronutrient transporters were studied by RT-PCR. Grain Cd and micronutrient content and agronomic parameters were also studied. Se supplementation increased plant growth, biomass, and yield under Cd stress. SEM and EDX analysis revealed that Se-Cd complex formed on root surfaces restricted Cd uptake by the roots preventing root damage. Soil analysis confirmed that Se decreased Cd bioavailability, restricted root to shoot Cd translocation, ultimately reducing Cd accumulation and restoring micronutrients in grain. This was further validated by fluorescent Leadmium dye staining. In (Se + Cd) treated seedlings, up-regulation of S metabolism and nutrient transporter genes also contributed to the mitigation of Cd stress. The Se supplementation can be considered as a cost-effective, ecofriendly and sustainable approach to produce Cd free rice cultivation in Cd polluted soil.
Climate change not only leads to high temperatures, droughts, floods, storms and declining soil quality, but it also affects the spread and mutation of pests and diseases, which directly influences plant growth and constitutes a new challenge to food security. Numerous hormones like auxin, ethylene and melatonin, regulate plant growth and development as well as their resistance to environmental stresses. To mitigate the impact of diverse biotic and abiotic stressors on crops, single or multiple phytohormones in combination have been applied. Melatonin is a multifunctional signaling molecule engaged in the development and stress response of plants. In the current review, we discuss the synthesis and action of melatonin, as well as its utilization for plant resistance to different stresses from the perspective of practical application. Simultaneously, we elucidate the regulatory effects and complex mechanisms of melatonin and other plant hormones on the growth of plants, explore the practical applications of melatonin in combination with other phytohormones in crops. This will aid in the planning of management strategies to protect plants from damage caused by environmental stress.
Pesticides including insecticides are applied in agricultural practices to control insect pests. However, their excessive usage often poses a severe threat to the growth, physiology, and biochemistry of plants. Here, responses of chickpea and greengram seedlings exposed to three fipronil (FIP) concentrations i. e. 100 (1x), 200 (2x) and 300 (3x) mu g mL- 1 was evaluated under in vitro. Among doses, 3x had a greater negative impact on germination attributes, root-shoot elongation, vigor indices, length ratios, and survival of seedlings. Besides, the morphological distortion in root tips, oxidative stress generation, and cellular death in fipronil-supplemented root seedlings were observed under scanning electron (SEM) and confocal laser scanning (CLSM), respectively. A significant (p <= 0.05) and pronounced upsurge in plant stressor metabolites such as proline, malondialdehyde (MDA), electrolyte leakage (EL), hydrogen peroxide (H2O2) content, and antioxidants enzymes in plant seedlings further confirmed the fipronil toxicity. In addition, a concentration-dependent decrease in respiration efficiency (RE) and ATP content in FIP-treated seedlings was observed. Reduced mitotic index (MI) and numerous chromosomal anomalies (CAs) in root meristematic cells of seedlings are a clear indication of insecticide-induced cytotoxicity. Furthermore, a dose-dependent increase in DNA damage in root meristematic cells of greengram revealed the genotoxic potential of fipronil. Conclusively, fipronil suggested phyto and cyto-genotoxic effects that emphasize their careful monitoring in soils before application and their optimum addition in soil-plant systems. It is high time to prepare both target-specific and slow-released agrochemical formulations for crop protection with concurrent safeguarding of the soil.
Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants that pose significant environmental and health risks. These compounds originate from both natural phenomena, such as volcanic activity and wildfires, and anthropogenic sources, including vehicular emissions, industrial processes, and fossil fuel combustion. Their classification as carcinogenic, mutagenic, and teratogenic substances link them to various cancers and health disorders. PAHs are categorized into low-molecular-weight (LMW) and high-molecular-weight (HMW) groups, with HMW PAHs exhibiting greater resistance to degradation and a tendency to accumulate in sediments and biological tissues. Soil serves as a primary reservoir for PAHs, particularly in areas of high emissions, creating substantial risks through ingestion, dermal contact, and inhalation. Coastal and aquatic ecosystems are especially vulnerable due to concentrated human activities, with PAH persistence disrupting microbial communities, inhibiting plant growth, and altering ecosystem functions, potentially leading to biodiversity loss. In plants, PAH contamination manifests as a form of abiotic stress, inducing oxidative stress, cellular damage, and growth inhibition. Plants respond by activating antioxidant defenses and stress-related pathways. A notable aspect of plant defense mechanisms involves plant-derived extracellular vesicles (PDEVs), which are membrane-bound nanoparticles released by plant cells. These PDEVs play a crucial role in enhancing plant resistance to PAHs by facilitating intercellular communication and coordinating defense responses. The interaction between PAHs and PDEVs, while not fully elucidated, suggests a complex interplay of cellular defense mechanisms. PDEVs may contribute to PAH detoxification through pollutant sequestration or by delivering enzymes capable of PAH degradation. Studying PDEVs provides valuable insights into plant stress resilience mechanisms and offers potential new strategies for mitigating PAH-induced stress in plants and ecosystems.
Wildfires are an ever-increasing issue due to the driving forces of climate change. Weather events that lead to higher wildfire potential are likely to increase and thus new fire management methods via more sustainable fire suppressant class A foams rather than retardants are being developed. However, despite their adherence to regulations, foam impact on targeted ecosystems, namely forests and forest trees is poorly studied. We aimed to investigate how three tree species (Pinus sylvestris, Alnus glutinosa and Picea abies) will react to a one-time class A foam application. Two separate trials were conducted. During the first the foam was applied to seeds and during the other - to 1-year-old seedlings. Tree growth and physiological status were evaluated. Stress criteria for cellular damage, non-antioxidant and antioxidant stress response and photosynthesis efficacy were measured. Results showed an obvious species effect, as all three reacted differently. The dose effect was also notable, with the higher application rate leading to a proportionally bigger response. Overall, pines were negatively impacted, spruce were positively affected, and alders didn't experience a notable change. This leads us to conclude that pending the limitation of this experiment the tested foam while phytotoxic in some cases, is unlikely to affect tree survival rates under field conditions and any physiological responses are likely transient in nature.
Many contaminated soils contain several toxic elements (TEs) in elevated contents, and plant-TE interactions can differ from single TE contamination. Therefore, this study investigated the impact of combined contamination (As, Cd, Pb, Zn) on the physiological and metabolic processes of lettuce. After 45 days of exposure, TE excess in soil resulted in the inhibition of root and leaf biomass by 40 and 48%, respectively. Oxidative stress by TE accumulation was indicated by markers-malondialdehyde and 5-methylcytosine-and visible symptoms of toxicity (leaf chlorosis, root browning) and morpho-anatomical changes, which were related to the change in water regime (water potential decrease). An analysis of free amino acids (AAs) indicated that TEs disturbed N and C metabolism, especially in leaves, increasing the total content of free AAs and their families. Stress-induced senescence by TEs suggested changes in gas exchange parameters (increase in transpiration rate, stomatal conductance, and intercellular CO2 concentration), photosynthetic pigments (decrease in chlorophylls and carotenoids), a decrease in water use efficiency, and the maximum quantum yield of photosystem II. These results confirmed that the toxicity of combined contamination significantly affected the processes of lettuce by damaging the antioxidant system and expressing higher leaf sensitivity to TE multicontamination.
In practical scenarios, tunnels may unavoidably cross active fault zones, leading to potentially severe damage by active fault displacement during earthquakes. Previous studies have failed to clearly establish an analytical method that considers both compressive and frictional behavior between tunnels and the soil that surrounds them, hindering the understanding of the tunnel -soil interaction. To address this, a finite element model (FEM) has been developed in this study to investigate the compressive and frictional characteristics of the tunnel -soil interaction of a reverse active fault -crossing tunnel. The model identifies six distinct zones of tunnel -soil interaction, namely, two active zones, two passive zones, and two separation zones. Building on these findings, the active fault -tunnel system was divided into three equivalent sub -systems, and an analytical method was established by creating and then combining equations for each sub -system. By applying the Pasternak Elastic Foundation Beam theory and Elastic theory, an analytical method is introduced that can simultaneously consider the distributed non-linear compressive interactive stress and non-linear frictional interactive stress. The results of the analytical method were validated with the FE results under three series of geological conditions. Through a quantitative examination of the similarity ratio and length of influence, the analytical results were seen to effectively reflect the characteristics of the soil -tunnel interaction and exhibit a good agreement with the FE results. It is concluded that the analytical model will serve as a computational reference for the design of reverse active fault -crossing tunnels.