Stresses, Volume 5, Issue 2 (June 2025) – 12 articles

Plant-growth-promoting rhizobacteria (PGPR) influence soil fertility, plant growth, tolerance to abiotic stress, resistance to herbivorous insects, and plant interactions with other organisms. While the effects of PGPR on plant growth, fruit yield, and induced defense responses have been extensively studied, the consistent positive outcomes have fueled rapid expansion in this research field. To evaluate PGPR impacts on plant growth and interactions with phytophagous insects, we conducted a systematic meta-analysis using publications from electronic databases (e.g., PubMed, Web of Science) that reported PGPR effects on plants and insects. Effects were categorized by plant family, PGPR genus, insect feeding guild, and insect–host specialization. Our analysis revealed that PGPR generally enhanced plant growth across most plant families; however, the magnitude and direction of these effects varied significantly among PGPR genera, indicating genus-specific interactions with host plants. When assessing PGPR-mediated reductions in phytophagous insects, we found that Pseudomonas, Rhizobium, and Bacillus exhibited the weakest negative effects on insect populations. PGPR significantly reduced both monophagous and polyphagous insects, with the most pronounced negative impacts on sucking insects (e.g., aphids, whiteflies). This study highlights critical patterns in PGPR-mediated plant growth promotion across taxa and the related differential effects on phytophagous insect activity. These insights advance our understanding of PGPR applications in agroecological production systems, particularly for integrated pest management and sustainable crop productivity. Full article

Aflatoxin B1 (AFB1), a potent mycotoxin, poses a significant threat to animal health through contaminated feed. Our study aims to investigate the neurotoxic effects of AFB1in chickens, with a special emphasis on the brain. Seven-day-old chickens were fed AFB1-contaminated feed (5 mg of AFB1/kg of feed) for two weeks, after which neurobehavioral assessments and biochemical analyses were conducted and compared to control chickens. In the open-field test, chickens exposed to AFB1 exhibited a reduction in locomotor activity and exploratory behavior. Additionally, AFB1 exposure increased the tonic immobility response. Biochemical analyses revealed that AFB1-contaminated feed reduced whole-brain acetylcholinesterase activity, suggesting impaired cholinergic neurotransmission. Indicators of oxidative stress in the brain revealed a reduction in glutathione levels, superoxide dismutase levels, and total antioxidant capacity, alongside an increase in malondialdehyde levels, indicating heightened oxidative stress in the brain. The neurotoxic effects of AFB1 were further supported by the upregulation of pro-inflammatory cytokine genes, including interleukin-1 beta, interleukin-6, interleukin-17, and inducible nitric oxide synthase, as determined by real-time quantitative polymerase chain reaction. Our study demonstrates that AFB1-contaminated feed influences chicken neurobehavioral outcomes and brain biochemistry and represents the inaugural evidence that AFB1 exposure markedly reduces AChE activity in the whole brain of chickens. Full article

Argentina is among the top consumers of herbicides, yet studies on their environmental and health impact remain scarce. This work aimed to evaluate the effects of herbicide exposure on Pomacea canaliculata as potential biomarkers of contamination. Specifically, we investigated whether paraquat (Pq) and fluroxypyr (Fx) alter enzymatic antioxidant defenses in tissues following acute exposure and induce histological modifications in the digestive gland (DG), particularly in symbiotic corpuscles, after chronic exposure. The nominal no-observed-effect concentration on lethality (NOEC_L) values were 3.62 µg/g dry mass (DM) for Pq and 10.42 µg/g DM for Fx. After acute exposure, superoxide dismutase activity decreased in the DG but increased in the kidney for both herbicides. Catalase activity decreased in the gills but increased in the kidneys of exposed snails, while glutathione-S-transferase activity increased in the DG and kidney after Pq exposure. Following chronic exposure (Pq: 1.45 µg/g DM; Fx: 6.94 µg/g DM), epithelial thickening and vacuolization were observed in Fx-exposed snails. Morphometric analysis of the DG showed that Pq reduced the epithelial occupancy of the symbiont’s vegetative form while increasing its cystic form. These findings indicate that both herbicides impact antioxidant defenses, DG function and host–symbiont interactions, reinforcing the suitability of P. canaliculata as bioindicator organisms. Full article

Exposing insects to mild and/or severe heat can protect them from future heat stress by regulating the expression of certain stress markers. In this study, 60 queen larvae, one day old, were divided into the following two groups: a control group of non-heat-treated mother queens (nH-T MQ) kept for 15 min at 34.5 °C and 70% relative humidity (RH) and a pre-heat-treated mother queen group (pH-T MQ) that was kept for 15 min at 41 °C and 70% RH. Then, 500 daughter workers were collected from brood combs of each group and incubated at room temperature (22 °C) for 30 min, then divided into five groups (n = 100); each group was incubated for one hour at 35, 40, 45, 50, and 55 °C, respectively. The expression levels of several antioxidant genes and markers in 10 workers of each treatment were assessed by relative quantitative Real-Time qPCR and/or ELISA. The pH-T MQ showed improved basal and dynamic expression of several genes and enzymes, which indicated a protective response against heat stress and the effectiveness of tissue hardening on the biological process and/or mechanisms in oxidative stress and antioxidant activity response. These recorded changes may have global implications by improving thermotolerance acquisition during heat stress conditions. Full article

The relationship between various central nervous system (CNS) disorders linked to pesticide exposure highlights a growing concern worldwide, as the extensive use of these compounds causes toxic effects on the CNS of non-target organisms. Reports indicate that exposure to pesticides, including carbamates, organophosphates, and pyrethroids, produces various adverse impacts on neurological function in humans, ranging from acute symptoms such as headaches and dizziness to long-term conditions leading to developmental delays in children, cognitive impairment, and neurodegenerative diseases, such as Parkinson’s and Alzheimer’s being among the most important. The scientific evidence suggests that pesticide exposure induces oxidative stress and disruptions in neurotransmission, resulting in neuronal damage and alterations in brain development. The review discusses scientific evidence of neurodegenerative disease development related to pesticide exposure, as well as alternatives to chemical pesticides used in agriculture, emphasizing Agroecological Crop Protection (ACP), which combines biological control, crop rotation, and natural predators and is presented as a practical approach to reducing reliance on pesticides. Organic farming methods, which employ natural substances and minimal input of chemicals, also offer safer alternatives. In addition, advances in biopesticides, which target specific pests without harming non-target organisms, provide promising solutions that protect the environment and human health. Pesticides are well-known environmental stressors that menace biodiversity and pose important threats to human health. Reducing pesticide use and remediating pesticide-polluted sites are urgent tasks to avoid adverse effects of pesticide exposure in non-target organisms. Full article

Soil microorganisms provide multifaceted benefits, including maintaining soil nutrient dynamics, improving soil structure, and instituting decomposition, all of which are important to soil health. Unpredictable weather events, including flooding from heavy rainfall, flash floods, and seawater intrusion, profoundly impact soil ecology, which is primarily challenged by flooding stress, and imbalances these microbial communities and their functions. This disturbance impairs the symbiotic exchanges between microbes and plants by limiting root exudates and habitats for microbes, as well as nutrient acquisition efficiency for plants. Therefore, this review comprehensively examines the changes in soil microbial communities that occur under flooding conditions. Flooding reduces soil oxygen (O₂) levels, limiting aerobic microbes but promoting anaerobic ones, including potential pathogens. In flooded soil, O₂ deficiency indirectly depends on the size of the soil particles and water turbidity during flooding. O₂ depletion is critical in shaping microbial community adaptation, which is linked to variations in soil pH, nutrient concentrations, and redox status, and fresh and saline water vary differently in terms of the adaptation of microorganisms. Wet soil alters soil enzyme activity, which influences microbial community composition. Notably, three-month post-flooding conditions allow microbial communities to adapt and stabilize more effectively than once-weekly flooding frequency. Based on the presence of aboveground species, fungi are found to reduce under flooding conditions, while nematode numbers, surprisingly, increase. Direct and indirect impacts between soil microbes and physio-chemical properties indicate positive or negative feedback loops that influence the soil ecosystem. Over the years, beneficial microorganisms such as plant-growth-promoting microbes (PGPMs) have been identified as important in regulating soil nutrients and microbial communities in wetland environments, thereby enhancing soil health and promoting better plant growth and development. Overall, understanding the mechanisms of belowground ecosystems under flooding conditions is essential for optimizing agricultural practices and ensuring sustainable crop production in flood-prone areas. Full article

The aim of the present study was to assess heavy metal tolerance and its accumulation potential in coastal nitrophilic species Rumex maritimus, and to study the possible effects of nitrogen fertilizer and salinity on the characteristics of metal-treated plants. Two experiments were performed in partially controlled greenhouse conditions: (1) gradual treatment with increasing concentrations of Cd, Pb, Cu, Mn, and Zn; and (2) acute treatment with Cd, Pb, and Cu on the background of different nitrogen fertilizer amendment rates (0.15 and 0.30 g L⁻¹ N) and salinity (50 and 100 mM). R. maritimus plants were extremely tolerant to treatment with all metals, with no negative effect on total leaf biomass both in the case of gradual or acute treatment. However, the number and biomass of dry leaves increased under high doses of heavy metals, and the effect was more pronounced in the case of acute treatment. All studied metals were excluded from the roots and young leaves, predominantly accumulating in the dry leaves, reaching 250 mg kg⁻¹ for Cd, 2000 mg kg⁻¹ for Pb, and 500 mg kg⁻¹ for Cu. In the second experiment, the presence of increased nitrogen in the substrate positively affected the growth of R. maritimus plants and their morphological response to heavy metals, but salinity affected metal accumulation. Photosynthesis-related parameters, leaf chlorophyll concentration, and the chlorophyll a fluorescence parameter Performance Index Total confirmed that heavy metals had no negative effect on the physiological state of photosynthetically active leaves. It is concluded that R. maritimus plants have exceptional potential for practical phytoremediation needs due to the high tolerance and accumulation potential for heavy metals. Full article

Cross-kingdom infections, where pathogens from one kingdom infect organisms of another, were historically regarded as rare anomalies with minimal concern. However, emerging evidence reveals their increasing prevalence and potential to disrupt the delicate balance between plant, animal, and human health systems. Traditionally recognized as plant-specific, a subset of phytopathogens, including certain fungi, bacteria, viruses, and nematodes, have demonstrated the capacity to infect non-plant hosts, particularly immunocompromised individuals. These pathogens exploit conserved molecular mechanisms, such as immune evasion strategies, stress responses, and effector proteins, to breach host-specific barriers and establish infections. Specifically, fungal pathogens like Fusarium spp. and Colletotrichum spp. employ toxin-mediated cytotoxicity and cell-wall-degrading enzymes, while bacterial pathogens, such as Pseudomonas syringae, utilize type III secretion systems to manipulate host immune responses. Viral and nematode phytopathogens also exhibit molecular mimicry and host-derived RNA silencing suppressors to facilitate infections beyond plant hosts. This review features emerging cases of phytopathogen-driven animal and human infections and dissects the key molecular and ecological determinants that facilitate such cross-kingdom transmission. It also highlights critical drivers, including pathogen plasticity, horizontal gene transfer, and the convergence of environmental and anthropogenic stressors that breach traditional host boundaries. Furthermore, this review focuses on the underlying molecular mechanisms that enable host adaptation and the evolutionary pressures shaping these transitions. To address the complex threats posed by cross-kingdom phytopathogens, a comprehensive One Health approach that bridges plant, animal, and human health strategies is advocated. Integrating molecular surveillance, pathogen genomics, AI-powered predictive modeling, and global biosecurity initiatives is essential to detect, monitor, and mitigate cross-kingdom infections. This interdisciplinary approach not only enhances our preparedness for emerging zoonoses and phytopathogen spillovers but also strengthens ecological resilience and public health security in an era of increasing biological convergence. Full article

Abiotic stresses like heat and salinity challenge crop production, but cultivar-specific adaptability and tolerance inducers can mitigate their impact. This study examined the growth and biochemical responses of five tomato varieties (Adeleza F1, Saint Anna F1, Goudski F1, Bronski F1, and Dunk F1) to thermopriming followed by salinity stresses. Thermopriming initially promoted growth but had variable effects on plant performance under combined stresses. Adeleza F1 and Bronski F1 were less affected, while Goudski F1 and Dunk F1 exhibited delayed development and reduced biomass under salinity stress. Thermopriming enhanced leaf chlorophyll content and antioxidant capacity in some varieties but inconsistently influenced leaf phenolics and flavonoids. Notably, increased flavonoid and anthocyanin accumulation in certain varieties suggests improved stress tolerance, albeit at the cost of growth. However, a consistent priming effect was not observed across all varieties, as combined heat and salt stress had a more severe impact than individual stresses. These findings highlight genotype-specific responses, underscoring the need for optimized (thermo-)priming protocols that balance growth and defense. This study provides valuable insights into the complex interplay of heat and salinity stress in tomatoes, emphasizing targeted strategies for enhancing crop resilience and informing future breeding programs. Full article

Cellular stressors have been demonstrated to exert a substantial influence on the functionality of organelles, thereby impacting cellular homeostasis and contributing to the development of disease pathogenesis. This review aims to examine the impact of diverse stressors, including environmental, chemical, biological, and physical factors, on critical organelles such as the cell membrane, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and membrane-less organelles. The intricate molecular mechanisms underlying cellular stress responses, encompassing oxidative stress, protein misfolding, and metabolic reprogramming, have the capacity to elicit adaptive responses or culminate in pathological conditions. The interplay between these stressors and organelle dysfunction has been implicated in a myriad of diseases, including neurodegenerative disorders, cancer, metabolic disorders, and immune-related pathologies. A comprehensive understanding of the mechanisms by which organelles respond to stress can offer valuable insights into the development of therapeutic strategies aimed at mitigating cellular damage. Full article

Mushrooms play an important role in ecosystem sustainability and are highly valued in medicine and human nutrition. Using AAS and biochemical methods of analysis, the antioxidant status and mineral composition of seven mushroom species (Armillaria mellea, Xeromocus illudens, Leccinum aurantiacum, Leccinum scrabum, Lactarium pubescens, Rusula vesca, and Lycoperpon molle Pers.) gathered near the Pechenganikel smelting plant in the Pasvik Nature Reserve of the Murmansk region were evaluated. The concentrations of Ni and Cu in the fruiting bodies of mushrooms were in the ranges of 0.43–39.7 and 7.9–45.9 mg kg⁻¹ d.w., respectively. An unusually high biological concentration factor (BCF) for Ni, Cu, and Zn levels in mushrooms grown in soils with a low amount of these elements indicates the low suitability of the mentioned parameter for mushroom characteristics in territories with an uneven distribution of elements in soil. On the other hand, selenium (Se) showed high BCF levels, exceeding 1, for all mushrooms tested, with the highest values associated with L. saccatum (5.17) and the lowest values with A. mellea (1.36). A significant excess (3.4) of the Recommended Daily Allowance (RDA) level per 30 g of dry mushrooms was recorded for Ni in Russula vesca gathered 6 km from the Ni/Cu smelting plant, and 1.3 excess of the RDA was recorded in L. scrabum grown in the vicinity of the Shuonyoka waterfall. No RDA excess was revealed for Cu. Positive correlations between Se, polyphenol content, and total antioxidant activity (AOA) (r = 0.915–0.926; p < 0.001) and a negative correlation between Cu–Se and Cu–AOA in Leccinum species indicate the important role of antioxidant defense and Se, particularly in Arctic mushroom growth and survival, providing a specific protection of mushrooms against Cu toxicity. Full article

Bacillus halotolerans, a halophilic bacterial species of the genus Bacillus, is emerging as a biological control agent with immense potential for sustainable agriculture, particularly in extreme conditions and environmental rehabilitation. This review summarizes the current state of research on B. halotolerans, emphasizing its diverse applications in the biocontrol of plant pathogens, plant growth promotion under salinity stress, nematode management, and bioremediation. B. halotolerans utilizes several mechanisms such as the production of siderophores and phytohormones, secretion of exopolysaccharides, and the release of antifungal and nematicidal compounds, which allows it to mitigate both abiotic and biotic stresses in various crops, including wheat, rice, date palm, tomato, and others. In addition, genomic and metabolomic analyses have revealed its potential for secondary metabolite production that improves its antagonistic and growth-promoting traits. Despite significant progress, challenges remain in translating laboratory results into field applications. Future research should focus on formulating effective bioinoculants and field trials to maximize the practical utility of B. halotolerans for sustainable agriculture and environmental resilience. Full article