Stresses, Volume 5, Issue 3 (September 2025) – 11 articles

Papaya cultivation is severely affected by the papaya ring spot virus (PRSV), for which one of the alternatives to counteract its damage is to use genetic sources of species and/or varieties tolerant or resistant to the virus. This study aimed to determine the tolerance or resistance of different papaya plant lines obtained through crosses and backcrosses between the Maradol variety and a wild species of Vasconcellea tolerant to PRSV. In this work, an evaluation was conducted on plant lines from a cross between a PRSV-tolerant species (Vasconcellea cauliflora) and the Maradol variety (Carica papaya), both belonging to the Caricaceae family. The study used RT-qPCR to measure the viral load and analyzed disease symptoms at two points (97 and 532 days after planting). Initially, it was observed that all the resulting papaya plants developed symptoms of PSRV; however, as time passed, the results showed that lines resulting from the Criolla, M4, and 54 crosses exhibited moderate tolerance, while papaya lines 89 and 90 proved to have high tolerance. Additionally, it was observed that the M4, 89, and 90 papaya lines exhibited disease recovery, as reflected in a decrease in viral loads and the characteristic symptomatology of the virus. Restoration from a viral infection can be associated with the activation of the plant’s RNA silencing mechanism, which can degrade or prevent the translation of viral RNA in plant cells, thus favoring recovery from the disease. Plants evaluated due to their tolerance and resistance levels could use the mechanisms mentioned above to recover from the damage caused by the PRSV. Full article

Sunflower (Helianthus annuus L.) is an essential oilseed crop known for its adaptability to harsh environments including drought. However, salinity stress, affecting over 20% of global agricultural land, poses a serious threat to its productivity. This study evaluated the response of 17 sunflower genotypes under salinity stress (200 mM NaCl) and optimum (0 mM NaCl) conditions in the laboratory. The experiment was arranged in a completely randomized design with three replications and was validated through a second experimental run. Measured parameters included germination percentage and speed, root and shoot length, biomass, and water content. Stress tolerance indices (STIs) for germination, seedling length, and biomass were calculated. Combined ANOVA showed that genotype and environment interactions significantly (p < 0.001) affected all measured traits. Salinity stress significantly reduced germination, seedling growth, and biomass across genotypes, with some experiencing complete germination inhibition. Genotypes 9, 14, 16, and 17 consistently maintained higher germination, seedling length, and biomass under stress, with high STIs, indicating tolerance to salinity stress during the early growth stages. These results identified genotypes 9, 14, 16, and 17 as promising candidates for breeding programs aimed at enhancing salinity tolerance, offering sustainable solutions for the utilization of saline soils and for enhancing food security. Future research should focus on the field-based validation of these genotypic responses. Full article

Anaerobic germination (AG) is a pivotal trait for successful direct-seeded rice cultivation, encompassing rainfed and irrigated conditions. Elite rice cultivars are often vulnerable to flooding during germination, resulting in poor crop establishment. This drawback has led to the exploration of AG-tolerant rice landraces, which offer valuable insights into the genetic underpinnings of AG tolerance. Over the years, substantial progress has been made in identifying significant quantitative trait loci (QTLs) associated with AG tolerance, forming the basis for targeted breeding efforts. However, the intricate gene regulatory network governing AG tolerance remains enigmatic. This comprehensive review presents recent advances in understanding the physiological and genetic mechanisms underlying AG tolerance. It focuses on their practical implications in breeding elite rice cultivars tailored for direct-seeding systems. Full article

Understanding the alterations to the shoot and root traits of rapeseed (Brassica napus) in response to salt stress is vital for improving its ability to thrive in saline-prone regions. This research aims to evaluate the responses of shoot and root traits of rapeseed at the vegetative stage under salt- and salicylic acid-induced stress in hydroponic culture. Five parents and ten F₃ segregants of rapeseed were subjected to three treatments: T1: control, T2: 8 dSm⁻¹ salt, and T3: 8 dSm⁻¹ salt + 0.1 mM salicylic acid at 21 days of age. Salinity stress significantly reduced the estimated root surface area by 54% compared to control, highlighting the plasticity of roots under stress. The simultaneous application of salt and SA did not alleviate the salinity stress, but rather reinforced the degree of stress and decreased the number of leaves, diameter of the main axis, chlorophyll content, and estimated root surface area by 18.5%, 15.4%, 38.8%, and 23%, respectively, compared to T2. The parental genotype M-245 followed by F₃ genotype M-232×M-223 accounted for the higher overall estimated root surface area. These results provide novel insights into the responses of root traits in rapeseed breeding lines under dual treatment, which hold promising implications for future rapeseed breeding efforts focused on sustainable rapeseed production. Full article

Fungi, from saprophytes to pathogens, face predictable daily fluctuations in light, temperature, humidity, and nutrient availability. To cope, they have evolved an internal circadian clock that confers a major adaptive advantage. This review critically synthesizes current knowledge on the molecular architecture and physiological relevance of fungal circadian systems, moving beyond the canonical Neurospora crassa model to explore the broader phylogenetic diversity of timekeeping mechanisms. We examine the core transcription-translation feedback loop (TTFL) centered on the FREQUENCY/WHITE COLLAR (FRQ/WCC) system and contrast it with divergent and non-canonical oscillators, including the metabolic rhythms of yeasts and the universally conserved peroxiredoxin (PRX) oxidation cycles. A central theme is the clock’s role in gating cellular defenses against oxidative, osmotic, and nutritional stress, enabling fungi to anticipate and withstand environmental insults through proactive regulation. We provide a detailed analysis of chrono-pathogenesis, where the circadian control of virulence factors aligns fungal attacks with windows of host vulnerability, with a focus on experimental evidence from pathogens like Botrytis cinerea, Fusarium oxysporum, and Magnaporthe oryzae. The review explores the downstream pathways—including transcriptional cascades, post-translational modifications, and epigenetic regulation—that translate temporal signals into physiological outputs such as developmental rhythms in conidiation and hyphal branching. Finally, we highlight critical knowledge gaps, particularly in understudied phyla like Basidiomycota, and discuss future research directions. This includes the exploration of novel clock architectures and the emerging, though speculative, hypothesis of “chrono-therapeutics”—interventions designed to disrupt fungal clocks—as a forward-looking concept for managing fungal infections. Full article

Among the numerous compounds released as a result of human activities, endocrine-disrupting chemicals (EDCs) have attracted particular attention due to their widespread detection in human biological samples and their accumulation across various ecosystems. While early research primarily focused on their effects on reproductive health, it is now evident that EDCs may impact neurodevelopment, altering the integrity of neural circuits essential for cognitive abilities, emotional regulation, and social behaviors. These compounds may elicit epigenetic modifications, such as DNA methylation and histone acetylation, that result in altered expression patterns, potentially affecting multiple generations and contribute to long-term behavioral phenotypes. The effects of EDCs may occur though both direct and indirect mechanisms, ultimately converging on neurodevelopmental vulnerability. In particular, the gut–brain axis has emerged as a critical interface targeted by EDCs. This bidirectional communication network integrates the nervous, immune, and endocrine systems. By altering the microbiota composition, modulating immune responses, and triggering epigenetic mechanisms, EDCs can act on multiple and interconnected pathways. In this context, elucidating the impact of EDCs on neurodevelopmental processes is crucial for advancing our understanding of their contribution to neurological and behavioral health risks. Full article

The climbing perch, Anabas testudineus, is one of the most widely distributed freshwater amphibious fishes in South and Southeast Asia, exhibiting terrestrial movements. Our experimental study aimed to investigate endocrinological and biochemical changes in the blood of climbing perch associated with their terrestrial movements. To achieve this, the fish were divided into two groups: one group was exposed to aquatic conditions for twenty minutes, while the other group was subjected to terrestrial conditions for the same duration through rapid water level decrease. In terrestrial conditions, the fish predominantly exhibit movements on land, whereas in aquatic environments, they primarily remain immobile or swim. Elevated levels of stress-induced cortisol and glucose after short-term exposure indicate a high-stress response involving both neuroendocrine and metabolic mechanisms. Changes in the activity of aspartate aminotransferase and increased concentrations of triglycerides in the blood serum suggest energy mobilization through aerobic metabolic pathways. Extreme environmental changes did not affect thyroid axis function, including deiodination, thereby maintaining essential physiological activities under new conditions. Additionally, the anaerobic metabolic pathway appears to be minimally utilized at the onset of terrestrial movement, as no significant changes in lactate dehydrogenase concentrations were observed. Overall, the terrestrial movements of the climbing perch are likely predominantly forced and associated with high stress. Full article

Masting, or the synchronous and intermittent production of seeds, can have profound consequences for Tropical Montane Cloud Forest (TMCF) tree populations and the trophic webs that depend on their mass flowering and seeds. Over the past 80 years, the importance of Fagus mexicana Martínez (Mexican beech) masting has become apparent in terms of conservation and management, promoting regeneration, and conserving endangered tree species, as well as the conscientious development of edible beechnuts as a non-timber forest product. The establishment of the relict-endemic Mexican beech is unknown, and several microenvironmental factors could influence natural regeneration. Thus, this study was conducted in two well-preserved Mexican beech forests to assess the influence of light incidence and soil moisture on the natural germination and seedling establishment of beeches. During two masting years (2017 and 2024), we assessed in situ beechnut germination and establishment. We tested the effect of the microenvironment of the oldest beeches on beechnut germination and seedling establishment. Our study highlights the complexity of the microenvironment of old beeches influencing the early stages of establishment and provides insights into possible conservation actions aimed at mitigating the impact of environmental change and humans. Full article

This study was conducted to examine the combined effects of monensin (MS) and 3 µm polystyrene microplastics (PEMPs) on the growth and stress-associated physiological responses of Microcystis aeruginosa under controlled laboratory conditions [temperature: 20 ± 1 °C, lighting: (30 ± 4) µmol m⁻² s⁻¹ (12 h:12 h light–dark photoperiod), growth medium: BG-11]. The experiments included MS concentrations of 0, 50, 250, and 500 µg/L and PEMPs concentrations of 0.25, 1.25, and 6 mg/L. Measurements included optical density (OD₇₃₀), chlorophyll ‘a’, cellular protein content, oxidative stress, and the activities of catalase (CAT) and guaiacol peroxidase (GPX). M. aeruginosa exhibited a significant increase in growth on day 7 at elevated MS concentrations across all PEMP levels. Similarly, MS and PEMP treatments had a significant interactive effect on cellular protein content on day 7. However, their combined effect on chlorophyll ‘a’ production was not significant. Oxidative stress measurements showed a dose-dependent decrease with increasing MS concentrations under PEMP administrations. Enzyme activity assays indicated that CAT activity increased while GPX activity decreased with higher MS concentrations. The results imply that co-contamination of PEMPs and MS has a significant impact on the growth and stress physiology of M. aeruginosa in aquatic ecosystems. Full article

Understanding how thermal variability affects marine ectotherms is essential for predicting species resilience under climate change. We investigated the physiological responses of juvenile Nodipecten subnodosus (lion’s paw scallop), offspring of two genetically distinct populations (Bahía de Los Ángeles and Laguna Ojo de Liebre), reared under common garden conditions and exposed to three temperature regimes: constant, regular oscillation, and stochastic variability. After 15 days of exposure, scallops underwent an acute hyperthermia challenge. We measured metabolic rates, scope for growth (SFG), tissue biochemical composition, and oxidative stress markers (SOD, CAT, GPx, TBARS). No significant differences were detected between populations for most traits, suggesting that phenotypic plasticity predominates over evolutionary divergence in thermal responses. However, the temperature regime significantly influenced metabolic, biochemical and oxidative stress markers, indicating that scallops in variable conditions compensated through improved energy balance and food assimilation but also showed higher oxidative stress compared to the constant regime. Following acute hyperthermic exposure, energy demand escalated, compensatory mechanisms were impaired, and scallops attained a state of physiological maintenance and survival under stress, irrespective of their population or prior thermal regime exposure. Full article

While genetic mechanisms in neurodevelopmental disorders are well studied, the mechanisms of environmental factors such as prenatal stress are less understood. Our lab previously characterized miRNA changes associated with stress during pregnancy in mouse brains and in maternal blood from mothers of children with ASD and indicated that prenatal stress can be linked to epigenetic markers. These miRNAs could be used as discovery biomarkers for stress exposure, as well as predictors of neurodevelopmental outcomes. In this pilot study, we gathered saliva samples and stress survey questionnaires from 83 pregnant African American women (ages 18–40) at the time of their ultrasound performed at 20 weeks. miRNA analysis was performed on the 10 highest- and 10 lowest-stress subjects. Out of 6631 miRNAs examined, 34 had significant differential expression, with 5 being upregulated and 29 downregulated in the high-stress group. Predicted targets of differentially expressed miRNAs revealed significant enrichment in neurodevelopmental pathways, including forebrain development, sensory system development, and neuronal growth regulation. This may suggest the potential developmental salience of these miRNA profiles. Future research will examine the neurodevelopmental outcomes of these pregnancies to determine the predictive potential of these miRNAs. This may help identify individuals at greatest risk after stress exposure during pregnancy. Full article