Stresses

Antarctic expeditions expose individuals to multiple and interacting stressors that may affect physiological regulation, sleep, and physical activity. This study investigated physiological responses in 28 male participants during the 34th Bulgarian Antarctic Expedition, who spent 30 days at the Antarctic research base. Physical activity and sleep duration were continuously monitored using three-dimensional inertial sensors. Salivary biomarkers of physiological responses associated with stress, cortisol, K⁺, Na⁺, the K⁺/Na⁺ ratio, total protein, and α-amylase activity, were measured before the expedition, weekly during deployment, and after return. Sleep duration increased significantly during Weeks 2 and 3 compared to Week 1. Light -intensity activity predominated over moderate-intensity activity and declined significantly over the monitoring period, whereas moderate-intensity activity decreased significantly during Week 3 compared with Week 1. Cortisol concentrations were significantly lower after return than during the pre-expedition period. Salivary K⁺ concentrations increased significantly during the Week 2 and subsequently decreased significantly after return, whereas Na⁺ concentrations remained stable throughout the mission but decreased after return. The K⁺/Na⁺ ratio declined significantly during the Weeks 2 and 3 and after expedition. Total salivary protein concentration and α-amylase activity increased at the Weeks 4 and 3, respectively, and both approached baseline following the participants’ return. The longitudinal changes in salivary biomarkers, together with alterations in physical activity and sleep duration, indicate dynamic physiological responses during and after Antarctic expedition. This minimally invasive, integrated approach may support further research on individual patterns of physiological adjustment and early deviations from adaptation, and may contribute to the development of personalized health monitoring strategies and timely preventive interventions during future Antarctic and other missions in extreme environments. Full article

The reproductive stage is a critical time in a plant’s life history when dealing with heat stress as the specific processes of meiosis, gametogenesis, anthesis, pollination, fertilization, and early seed development all occur within comparatively narrow temperature limits. Much of the importance of flowering is tied directly to temperature, both for the timing of reproductive transition and the ability for male and female reproductive tissues to survive exposure to damaging heat. Ambient-temperature sensing is linked to flowering via regulatory modules that involve phytochrome B, EARLY FLOWERING 3 (ELF3), PHYTOCHROME INTERACTING FACTOR 4 (PIF4), FLOWERING LOCUS T (FT), FLOWERING LOCUS M (FLM), SHORT VEGETATIVE PHASE (SVP), and the light–circadian components. Conversely, when temperature is harmful, protective responses involve other cellular mechanisms such as activation of heat-shock transcription factors (HSFs), heat-shock proteins (HSPs), endoplasmic-reticulum protein quality control, calcium and reactive oxygen species (ROS) signaling, antioxidant systems, hormone regulation, metabolic reprogramming, autophagy and DNA-repair pathways. Male reproductive development is often very sensitive, especially at meiosis, during formation of the tetrad, microspore development, during the maturation of pollen, and during the growth of the pollen tubes, although injury to pistils, ovules and the post-fertilization tissues may solely have an effect on the restriction of fertilization and seed set. Phenological heat escape and intrinsic reproductive thermotolerance are genetically separable but can be complementary aspects of adaptation, as revealed by natural allelic variation, QTL mapping, genomic prediction and marker assisted selection. This review summarizes molecular, genetic and physiological evidence, to propose that, to ensure stable yields at high temperatures, there is a need to coordinate optimization of reproductive timing, cell and development thermotolerance, and post-fertilization sink stability. Full article

Caenorhabditis elegans has served as a model for the unfolded protein response of the endoplasmic reticulum (UPR-ER) and, separately, the oxidative stress response coordinated by SKN-1/Nrf. The oxidative protein folding in the ER generates reactive oxygen species, which is one reason why these systems are frequently studied together. Additionally, numerous stressors activate both pathways simultaneously. Although these molecular chaperones are critical to both processes, current research rarely considers them as an integrative concept, instead categorizing the interaction strictly within different pathway mechanisms. This review focuses on the chaperone systems themselves, including the HSP-4 and protein disulfide isomerases that are located in the ER, the HSP-70 family that resides in the cytoplasm and is controlled by HSF-1, and HSP-6 and HSP-60 that function in the mitochondria and are regulated by ATFS-1. Oxidative stress interacts with each compartment in a manner that is mechanistically distinct. This corresponds to direct redox chemistry in the ER, transcriptional coupling by SKN-1, and compartment-specific ROS-sensing evidence in the mitochondria and cytoplasm. Oxidative stress and chaperone induction converge through multiple independent pathways rather than a single sequential pathway, and this convergence deteriorates with age in a pathway- and tissue-specific manner, as shown by studies focusing on translational chaperone loss, particulate matter exposure, and proteasome-mediated degradation. Finally, we address some outstanding issues, such as the translational relevance to human diseases associated with ER stress and the functioning of redox-regulated chaperone mechanisms in C. elegans. Full article

High-intensity blue light is a powerful regulatory signal for plants, but its excess induces oxidative stress requiring rapid diagnosis. This study evaluated the potential for early detection of changes in the spectral characteristics of microgreen canopy cover caused by high-intensity blue light (PPFD 2500 µmol·m⁻²·s⁻¹, 12 h) in five species of microgreens (Helianthus annuus, Pisum sativum, Eruca sativa, Hordeum vulgare, Raphanus sativus ‘Sango Purple’) using hyperspectral imaging (450–950 nm) and machine learning. A Random Forest model trained on 85 vegetation indices classified light stress with high accuracy (Accuracy > 93%, Kappa > 0.87, F1-score > 93%) and detected spectral changes characteristic of light stress as early as 1–3 h of exposure. SHAP analysis identified carotenoid-sensitive indices (PRI, CCI, PRICI2) and chloroplast movement and stress indices (CMI, LSI_Red, LSI_Norm, Carter5) as the most informative predictors. It is assumed that the primary mechanism underlying early spectral changes was chloroplast avoidance rather than pigment degradation, as confirmed by the reversibility of canopy bleaching, rapid recovery of maximum quantum yield of photosystem II, and unchanged chlorophyll and carotenoid contents. Sunflower and radish were the most sensitive species to high-dose blue light, while barley was the least sensitive. LSI_Red was identified as a reliable qualitative marker of light stress that does not require a control sample, simplifying its use in automated monitoring systems. These findings demonstrate the effectiveness of hyperspectral phenotyping for non-invasive, rapid diagnosis of light stress in microgreens, providing a tool for optimising lighting regimes in controlled environment agriculture. Full article

Sunflower broomrape (Orobanche cumana Wallr. var. helianthi) is traditionally regarded as strictly host-specific, parasitizing cultivated sunflower (Helianthus annuus L.). Arctium lappa L. (burdock) was recently identified as a novel susceptible host, but whether this susceptibility is uniform across different sunflower O. cumana races remained unknown. Here, three naturally occurring A. lappa populations from north-eastern Bulgaria and a susceptible sunflower inbred line (AD-66) were challenged under controlled glasshouse conditions with three O. cumana races of increasing virulence (F, G, and G+/H), and tubercle number was recorded 45 days after inoculation (n = 50 plants per host × race combination). Race F was largely unable to establish infection on A. lappa (0–4% infected plants) while remaining highly infective on sunflower (96%), whereas races G and G+/H retained substantial infectivity on A. lappa (68–96%), though with up to two-to-three-fold lower mean tubercle numbers than on sunflower. A negative binomial generalized linear model showed that race accounted for the largest share of explained variation in tubercle number, with weaker and less robust host and host × race effects. Additive Main Effects and Multiplicative Interaction (AMMI) and genotype plus genotype-by-environment (GGE) biplot analyses further resolved this interaction into a single dominant axis, along which A. lappa was disproportionately susceptible to race G+/H and disproportionately resistant to race F. These results demonstrate that, under controlled glasshouse conditions, A. lappa is a race-dependent, alternative host for O. cumana. Whether this translates into a field-relevant reservoir capacity beyond the sunflower cropping cycle remains to be established. Full article

This review highlights the significant capacity of microalgae to produce a wide range of phenolic compounds and other secondary metabolites. It discusses the major abiotic stress factors affecting microalgal cells and their influence on secondary metabolite production and accumulation. Microalgae synthesize numerous bioactive compounds that contribute to their biological significance, such as antimicrobial, antioxidant, and antiviral properties. These biological properties make microalgae promising resources for various applications in pharmaceuticals, functional foods, biofertilizers, biopolymers, and other industrial sectors. Moreover, several abiotic stressors—such as salinity, light intensity, chemical exposure, and heavy metals—have been reported to stimulate the biosynthesis of secondary metabolites in microalgae. These stress conditions are often associated with increased production of protective compounds that help mitigate reactive oxygen species (ROS)-mediated oxidative stress within algal cells. This review also summarizes the impact of abiotic stress on key classes of secondary metabolites, particularly phenolic compounds, carotenoids, and flavonoids, whose concentrations tend to increase under stress conditions. Understanding the relationship between oxidative stress and secondary metabolite biosynthesis in microalgae may provide valuable insights for optimizing their biotechnological and industrial applications. Full article

Oxidative stress is a major constraint limiting animal health and productive performance by disrupting redox homeostasis, mitochondrial function, intestinal integrity, and mineral metabolism. Agronomic biofortification of forage with essential trace minerals represents a promising nutritional strategy; however, its physiological and molecular mechanisms remain poorly understood. This study evaluated the effects of dietary zinc–iron (Zn–Fe) biofortified alfalfa on oxidative stress, antioxidant defense, mineral transport, mitochondrial bioenergetics, intestinal barrier integrity, inflammatory responses, tissue mineral deposition, and growth performance in guinea pigs. Forty-eight male guinea pigs were allocated to six experimental groups according to dietary treatment (control, Zn-biofortified alfalfa, or Zn–Fe biofortified alfalfa) and oxidative stress status. Oxidative biomarkers, antioxidant enzyme activities, inflammatory mediators, mineral concentrations, targeted RT–qPCR, mitochondrial function, intestinal histomorphology, and multivariate physiological analyses were performed. Zn–Fe biofortified alfalfa markedly reduced reactive oxygen species, malondialdehyde, protein carbonyls, 8-hydroxy-2′-deoxyguanosine, advanced oxidation protein products, and the oxidative stress index while significantly increasing superoxide dismutase, catalase, glutathione peroxidase, total antioxidant capacity, and the glutathione redox ratio. Targeted gene-expression analysis demonstrated coordinated upregulation of intestinal mineral transporters (ZIP4, DMT1, and MT1), activation of the Nrf2 antioxidant pathway, increased expression of mitochondrial regulatory genes, and suppression of inflammatory mediators. These molecular responses were accompanied by improved ATP production, mitochondrial membrane potential, respiratory-chain activity, preservation of intestinal villus architecture, enhanced expression of tight-junction proteins, increased tissue Zn and Fe deposition, superior feed efficiency, and greater body weight gain. Integrated physiological analyses consistently identified the Zn–Fe biofortified treatment as the highest-performing physiological phenotype, indicating coordinated adaptation across multiple biological systems. These findings demonstrate that Zn–Fe biofortified alfalfa enhances oxidative stress resilience through simultaneous regulation of mineral transport, antioxidant defense, mitochondrial bioenergetics, intestinal barrier integrity, and systemic physiological performance. Agronomic biofortification of forage therefore represents a promising nutritional strategy for improving animal health, mineral utilization, and productive efficiency under oxidative stress. Full article

Soil salinization stands out as a major factor contributing to the shrinkage of arable land. This study explored the salt tolerance mechanism of tillers in CMG and 9311 by evaluating morphophysiological, transcriptomic, and metabolomic characteristics under 0.3% NaCl stress. The activities of SOD, POD, and APX in the tiller nodes of the salt-tolerant variety CMG were higher than those of 9311, while the levels of MDA and hydrogen peroxide in the tiller nodes of CMG were relatively low. Both varieties responded to salt stress mainly by activating pathways such as amino acid metabolism (alanine, aspartic acid, glutamic acid metabolism, and arginine biosynthesis), amino acid acyl-trNA biosynthesis, oxidative phosphorylation, and phenylpropanin biosynthesis. The varieties differed in that CMG tillering nodes also have unique pathways of “glycerophospholipid metabolism” (related to membrane lipid remodeling) and “biosynthesis of the cuticle, suppositories and waxes”, which can effectively reduce water loss and prevent sodium ions from entering. In addition, CMG can regulate more plant hormone signaling pathways to coordinate the expression and metabolic activities of downstream defense genes, such as abscisic acid (ABA) and jasmonic acid (JA), and other hormone signals. After salt stress, the CMG tiller nodes tend to strengthen themselves, enabling them to resist stress and reduce Na⁺ toxicity, while the 9311 tiller nodes, under the condition of activating basal metabolism, transfer to the leaves to enhance photosynthetic efficiency and resist stress. Through comprehensive screening and analysis of the genes and metabolites of CMG and 9311 tillers under salt stress, the molecular mechanisms and metabolic pathway dynamics involved in their salt stress response were identified, thus providing a new perspective for in-depth research on rice salt tolerance mechanisms. Full article

Global demand for cape gooseberry fruits has experienced significant growth in recent years. These fruits exhibit a physiological disorder known as cracking, caused by irregular water supply to the crop and calcium deficiencies. Therefore, the effects of different irrigation levels and calcium fertilization on fruit quality and on enzymes such as polygalacturonase, which is involved in cell wall degradation during ripening and stress responses. A completely randomized block design was used, with three blocks representing irrigation frequencies (4, 9, and 14 days) and twelve treatments arranged in a 4 × 3 factorial design. The first factor was the irrigation coefficient (0.7, 0.9, 1.1, and 1.3 of evaporation), and the second was calcium fertilization (0, 50, and 100 kg ha⁻¹ of Ca²⁺ applied as calcium nitrate). Calcium fertilization did not affect the fruits’ calcium concentration [Ca²⁺]. Cape gooseberry plants fertilized with 50 and 100 kg ha⁻¹ of calcium accumulated 57% and 107% more of this nutrient in the leaves compared to the control, while the calyx accumulated 72% more with calcium application. Irrigation coefficients of 1.1 and 1.3 of ETc reduced [Ca²⁺] in the leaves by 24% compared to irrigation coefficients of 0.7 and 0.9. [Ca²⁺] in the calyx decreased by 25% when the irrigation frequency was increased from 4 to 14 days. Numerically, the highest fruit concentrations of K⁺, Ca²⁺, and Mg²⁺ were observed under the combination of a 50 kg ha⁻¹ calcium dose, a 0.9 irrigation coefficient, and a 9-day irrigation frequency. Polygalacturonase activity was significantly reduced by calcium fertilization, but irrigation treatments did not produce statistically significant effects. Full article

Aging is characterized by a progressive decline in physiological resilience and increased susceptibility to chronic diseases, including neurodegenerative disorders. Emerging evidence indicates that low-dose stressors (collectively termed hormetic stimuli) activate adaptive cellular responses that enhance stress resistance, promote repair mechanisms, and ultimately extend healthspan. This narrative review synthesizes current knowledge on hormesis in the context of aging, with a focus on key molecular pathways including nuclear factor erythroid 2-related factor 2 (Nrf2), sirtuins, autophagy, and mitohormesis. We examine how lifestyle interventions (physical exercise, caloric restriction, mild thermal stress) and emerging pharmacological agents induce beneficial adaptive responses, while critically evaluating their translational potential in clinical and public health settings. Special emphasis is placed on the role of hormesis in counteracting neurodegeneration, the utility of autophagy and systemic aging biomarkers (epigenetic clocks, inflammaging scores) for precision dosing, and the limitations imposed by inter-individual variability, age-related decline in adaptive capacity, and risks of overexposure. Importantly, this review distinguishes experimentally demonstrated hormetic responses from broader adaptive stress responses and critically evaluates situations in which hormetic mechanisms may be insufficient, maladaptive, or clinically inappropriate. Understanding the delicate balance between beneficial and detrimental stress responses is essential for leveraging hormesis as a robust strategy to counteract aging and age-related diseases. We further propose a multilevel framework integrating molecular mechanisms with clinical outcomes, positioning hormesis as a key determinant of adaptive resilience (stress resistance, mitochondrial function, HRV, VO₂max) in aging. Full article

Temperature is a major environmental determinant of flowering time and reproductive success in plants. Ongoing global warming is changing flowering phenology across natural and agricultural ecosystems, yet the mechanisms by which ambient temperature regulates the transition to reproduction remain less fully resolved than those underlying photoperiodic flowering and vernalization. This review synthesizes eco-physiological and molecular evidence for temperature-dependent flowering across plant groups and terrestrial ecosystems. It considers the development of the florigen concept, the identification of FLOWERING LOCUS T (FT) and related phosphatidylethanolamine-binding protein family members, and the integration of temperature signals with flowering activators and repressors. Particular attention is given to the thermosensory pathway, including alternative splicing, chromatin regulation, membrane-associated signaling, phase separation and temperature-dependent accumulation or stability of regulatory proteins. The review also examines phenological responses to rising temperatures in bulbous geophytes, Arctic and boreal species, subtropical and tropical crops, and desert plants. Available evidence indicates that the temperature requirements for floral initiation, their organogenesis and anthesis vary widely among species and developmental stages, and that these optima reflect life-history strategy, origin and adaptation to seasonal temperature regimes. Full article

The genus Euterpe, which includes açaí palm (Euterpe oleracea) and juçara palm (Euterpe edulis), plays an important socioeconomic and environmental role in Brazil. However, soil and water salinization is a global issue that compromises agricultural productivity by affecting plant physiological and metabolic processes. This study aimed to evaluate the physiological responses of young açaí and juçara plants under salt stress. The experiment was conducted in a randomized complete block design in a 5 × 2 factorial arrangement, consisting of five irrigation water salinity levels (0.1, 1.0, 2.0, 3.0, and 5.0 dS m⁻¹) and two Euterpe species (açaí and juçara), with four replicates. After 104 days of stress exposure, gas exchange, chlorophyll ‘a’ fluorescence, relative chlorophyll index (SPAD), and sodium, chloride, and phenolic compounds were evaluated. Increasing salinity caused linear reductions in the maximum quantum yield and potential photochemical efficiency of PSII, accompanied by an increase in F₀/Fm, indicating impaired PSII photochemical performance and photoinhibition. Stomatal conductance and transpiration also decreased significantly with increasing salinity, with reductions of up to 41.33% and 35.48%, respectively, at the highest salinity level. Salt stress negatively affected the physiological performance of both palm species through stomatal limitation and reduced photosystem II efficiency. However, açaí plants exhibited greater tolerance to salt stress than juçara plants. Full article

Despite the growing demand for sustainable agricultural systems, the long-term effects of tillage practices remain controversial. No-tillage (NT) systems offer several potential benefits, including improved soil structure, enhanced soil biological activity, and reduced environmental stress, but their application can also be associated with challenges such as difficulty in weed control or variable crop yield. Although previous studies have extensively investigated the effects of NT systems on soil and crop, limited knowledge is available about the cellular adaptation mechanisms of plants, especially gene expression and biochemical responses. The aim of this study was to compare the effects of conventional tillage (CT) and NT systems in sunflower plants using an integrated transcriptomic and biochemical approach. We performed genome-wide transcriptomic analysis based on next-generation sequencing on leaf samples from three different field sites, supplemented by measurements of biochemical parameters related to selected metabolic processes. Exploratory transcriptomic analysis indicated that several gene expression changes related to primary metabolic processes occurred in plants grown in the NT system compared to the CT system. These included processes related to photosynthesis, cellular respiration, carbohydrate metabolism and the biosynthesis of some amino acids. In parallel, we observed transcriptional patterns indicating increased activity of several secondary metabolic pathways, which may be related to adaptation mechanisms to environmental stress. Determination of total soluble sugar, crude protein, total phenolics and total flavonoids provided independent biochemical support for the changes indicated by the transcriptomic results. Our results suggest that the tillage system affects the cellular regulatory processes of sunflower. During adaptation to a no-tillage environment, plants can simultaneously maintain basic metabolic processes and activate defense mechanisms that may contribute to adaptation to changed growing conditions. Our study contributes to a better understanding of the molecular and physiological consequences of tillage systems in plants. Full article

Free proline accumulation is an important physiological trait frequently associated with plant responses to changing environmental conditions. This study investigated seasonal patterns of free proline concentration in the underground organs of four Mediterranean geophytes—Pancratium maritimum, Sternbergia lutea, Iris germanica, and Cyclamen graecum—under natural environmental conditions. Monthly temperature and precipitation data were incorporated to examine the influence of environmental factors on proline dynamics. The results revealed clear species-specific and seasonal variation in proline accumulation. Sternbergia lutea exhibited the highest proline concentrations and the greatest seasonal variability, whereas Iris germanica maintained comparatively low and stable levels. To evaluate descriptive performance, both a linear seasonal regression model and a Random Forest regression model were applied. The linear model showed moderate predictive performance (R² = 0.488), slightly outperforming the Random Forest model (R² = 0.350). Overall, the findings demonstrate clear species-specific differences in seasonal proline accumulation that are consistent with differing physiological responses among the studied geophytes. The pronounced interspecific differences observed in this study suggest that proline accumulation is a species-specific physiological trait rather than a universal response among Mediterranean geophytes. The integration of physiological measurements with statistical and machine learning approaches provides an exploratory framework for examining seasonal variation in proline accumulation and evaluating statistical approaches for describing species-specific patterns. Full article

Oxidative stress poses significant challenges for fungi inhabiting extreme environments. Elevated salinity frequently induces the excessive production of reactive oxygen species (ROS), which can damage cellular components and impair growth. In response, fungi—common inhabitants of extreme environments—activate coordinated adaptive mechanisms, including antioxidant defense systems and other stress-related pathways. In the present study, a newly isolated strain, Trichoderma afroharzianum B2.2, obtained from the poorly studied saline habitat of Atanasovsko Lake (Bulgaria), was investigated. The cellular response of this moderately halotolerant strain to increased salinity was characterized. Biomarkers of oxidative stress were evaluated, and the involvement of key enzymes from glycolysis and the pentose phosphate pathway in the strain’s adaptation to elevated salinity was examined. Understanding adaptations to salt environments is crucial not only for elucidating fungal survival mechanisms under extreme conditions but also for their potential applications in biotechnology, ecology, and food safety, particularly in the context of increasing ecosystem salinization and climate change. Full article

Water deficit represents a major environmental constraint that severely limits the growth and yield of common bean (Phaseolus vulgaris L.). Although inoculation with plant growth-promoting rhizobacteria (PGPR) has emerged as a promising strategy to mitigate drought-induced stress, the efficacy of specific strains, such as Priestia aryabhattai CMAA 1363, remains to be fully elucidated. This study evaluated the morpho-agronomic and biochemical responses of common bean to seed inoculation with P. aryabhattai CMAA 1363 under two contrasting irrigation regimes: 100% (well-watered) and 40% (water-restricted) of available water capacity (AWC) under greenhouse conditions. Water restriction significantly compromised plant performance, reducing plant and pod length, root dry biomass, and yield components (pod and grain counts, and total grain mass). Conversely, bacterial inoculation enhanced vegetative traits, increasing plant length by approximately 15% and root dry biomass by approximately 25% compared to non-inoculated controls. Notably, under severe water deficit (40% AWC), inoculated plants achieved a 20% increase in total grain mass per plant relative to their non-inoculated counterparts. Biochemical profiling indicated that inoculation effectively attenuated oxidative stress, as evidenced by lower malondialdehyde (MDA) accumulation and modulated superoxide dismutase (SOD) activity, while water-stressed plants adapted by accumulating total soluble sugars and increasing peroxidase (POD) activity. Overall, P. aryabhattai CMAA 1363 promotes vegetative development, preserves grain production under drought, and orchestrates antioxidant defense mechanisms, highlighting its potential as a sustainable bioinput to improve common bean resilience in water-limited agricultural systems. Full article

In container-grown ornamental shrub production, limited substrate volume can rapidly alter plant water status and affect leaf-level physiological performance. A randomized block experiment was conducted to evaluate the effects of three foliar-applied biostimulants, BiStep, Kelpak, and Yeald Plus, compared with an untreated control in container-grown Forsythia × intermedia ‘Beatrix Farrand’. Each treatment comprised 25 plants distributed across five blocks. Stomatal density, stomatal length, leaf transpiration, net photosynthesis, total chlorophyll content, and gravimetrically determined daily water loss were measured. Compared with the control, BiStep significantly increased stomatal density, whereas Yeald Plus significantly decreased it. Kelpak and Yeald Plus significantly increased stomatal length compared with the control. Leaf transpiration was significantly lower under Kelpak and Yeald Plus than in the control, while Kelpak and BiStep had significantly higher net photosynthetic rates than Yeald Plus, whereas the control did not differ significantly from any treatment. Total chlorophyll content did not differ significantly among treatments. Whole-plant daily water loss was higher in all biostimulant-treated plants than in the control, with the highest values recorded under BiStep. These results show that the tested biostimulants induced treatment-specific physiological changes rather than a uniform response. Kelpak provided the most favorable leaf-level balance by reducing instantaneous transpiration while maintaining high photosynthetic activity, whereas BiStep promoted a more water-demanding physiological profile. Based on these outcomes, Kelpak may be recommended where improved leaf-level physiological efficiency is required under container-grown nursery conditions, while BiStep should be applied only with adequate irrigation management. Full article

Nanoscale zerovalent iron (nZVI) has shown promise for soil remediation. This study examined the impact of this nanomaterial on barley and wheat grown in alkaline soil throughout a complete growth cycle, to assess its potential as a fertilizer and to understand its behavior in an uncontaminated matrix. A greenhouse experiment was conducted in which barley and wheat plants were grown in soil treated with a commercial nZVI slurry at 0 and 5% (equivalent to 0 and 8 g kg⁻¹). Physiological parameters were monitored throughout the growth cycle, and plants were harvested after five months. Biomass production, impact on root and leaf ultrastructure, and the concentrations of Fe and other nutrients were determined in several plant tissues. Soil physicochemical properties were not adversely affected by nZVI application, and an increase in Fe availability was observed regardless of the species, from 1 mg kg⁻¹ to 5.2 and 6.6 mg kg⁻¹ in barley and wheat soils, respectively. However, this increase did not translate into higher Fe accumulation in plant tissues at the end of the growth cycle, nor did it enhance plant growth in either species. Therefore, under the experimental conditions evaluated, the application of nZVI as an iron fertilizer cannot be recommended. Notably, both crops exhibited a greater sensitivity to nZVI during early stages of development, as evidenced by significant reductions in chlorophyll content and increased oxidative stress. These initial adverse effects were progressively alleviated as plant growth advanced, with no detectable alterations in cellular ultrastructure, allowing both species to complete their growth cycle. Full article

Cadaverine is a lysine-derived diamine that remains less studied than the canonical plant polyamines putrescine, spermidine, and spermine. Its polycationic nature suggests it may influence membrane stability, ionic balance, redox regulation, and stress-related metabolic adjustments, but its specific contribution to plant resilience to abiotic stress remains poorly characterized. This systematic review, evidence map, and exploratory meta-analysis synthesized the published literature on cadaverine-associated responses in plants exposed to abiotic stress. The object of analysis was the existing body of literature, and the quantitative component summarized data extracted from eligible studies rather than generating new experimental results. The review examined whether the available literature supports a role for cadaverine beyond its description as a stress-associated metabolite, particularly regarding transport, oxidative stress mitigation, photosynthetic protection, water status, ionic homeostasis, and growth maintenance. The evidence indicates that cadaverine is primarily associated with beneficial physiological responses to stress, particularly when applied exogenously. However, the magnitude of the response varies across species, stress types, doses, application methods, and response variables. Mechanistically, cadaverine may contribute to stress tolerance by activating antioxidant enzymes, reducing oxidative damage, stabilizing membranes, protecting the photosynthetic apparatus, promoting osmotic adjustment, and modulating cation transport. However, endogenous cadaverine dynamics and several proposed signaling connections remain insufficiently validated. Overall, cadaverine emerges as a promising regulatory candidate for fundamental research on plant stress physiology. In contrast, its agronomic use still requires standardized dose–response studies, comparative analysis with other polyamines, and greenhouse and field validation. Full article