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Abstract Globally, drought stress poses a significant threat to crop productivity. Improving the drought tolerance of crops with microbial biostimulants is a sustainable strategy to meet a growing population’s demands. This research aimed to elucidate microbial biostimulants’ (Plant Growth Promoting Rhizobacteria) role in alleviating drought stress in oil-seed crops. In total, 15 bacterial isolates were selected for drought tolerance and screened for plant growth-promoting (PGP) attributes like phosphate solubilization and production of indole-3-acetic acid, siderophore, hydrogen cyanide, ammonia, and exopolysaccharide. This research describes two PGPR strains: Acinetobacter calcoaceticus AC06 and Bacillus amyloliquefaciens BA01. The present study demonstrated that these strains (AC06 and BA01) produced abundant osmolytes under osmotic stress, including proline (2.21 and 1.75 µg ml− 1), salicylic acid (18.59 and 14.21 µg ml− 1), trehalose (28.35 and 22.74 µg mg− 1 FW) and glycine betaine (11.35 and 7.74 mg g− 1) respectively. AC06 and BA01 strains were further evaluated for their multifunctional performance by inoculating in Arachis hypogaea L. (Groundnut) under mild and severe drought regimes (60 and 40% Field Capacity). Inoculation with microbial biostimulants displayed distinct osmotic-adjustment abilities of the groundnut, such as growth parameters, plant biomass, photosynthetic pigments, relative water content, proline, and soluble sugar in respective to control during drought. On the other hand, plant sensitivity indexes such as electrolyte leakage and malondialdehyde (MDA) contents were decreased as well as cooperatively conferred plant drought tolerance by induced alterations in stress indicators such as catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD). Thus, Acinetobacter sp. AC06 and Bacillus sp. BA01 can be considered as osmolyte producing microbial biostimulants to simultaneously induce osmotic tolerance and metabolic changes in groundnuts under drought stress.

Abiotic stress reduces plant yield and quality. WRKY transcription factors play key roles in abiotic stress responses in plants, but the molecular mechanisms by which WRKY transcription factors mediate responses to drought and osmotic stresses in apple (Malus × domestica Borkh.) remain unclear. Here, we functionally characterized the apple Group III WRKY gene MdWRKY115. qRT-PCR analysis showed that MdWRKY115 expression was up-regulated by drought and osmotic stresses. GUS activity analysis revealed that the promoter activity of MdWRKY115 was enhanced under osmotic stress. Subcellular localization and transactivation assays indicated that MdWRKY115 was localized to the nucleus and had a transcriptional activity domain at the N-terminal region. Transgenic analysis revealed that the overexpression of MdWRKY115 in Arabidopsis plants and in apple callus markedly enhanced their tolerance to drought and osmotic stresses. DNA affinity purification sequencing showed that MdWRKY115 binds to the promoter of the stress-related gene MdRD22. This binding was further verified by an electrophoretic mobility shift assay. Collectively, these findings suggest that MdWRKY115 is an important regulator of osmotic and drought stress tolerance in apple.

Osmotic stress caused by low-temperature, drought and salinity was a prevalent abiotic stress in plant that severely inhibited plant development and agricultural yield, particularly in tea plant. Jasmonic acid (JA) is an important phytohormone involving in plant stress. However, underlying molecular mechanisms of JA modulated osmotic stress response remains unclear. In this study, high concentration of mannitol induced JA accumulation and increase of peroxidase activity in tea plant. Integrated transcriptome mined a JA signaling master, MYC2 transcription factor is shown as a hub regulator that induced by mannitol, expression of which positively correlated with JA biosynthetic genes (LOX and AOS) and peroxidase genes (PER). CsMYC2 was determined as a nuclei-localized transcription activator, furthermore, Protein-DNA interaction analysis indicated that CsMYC2 was positive regulator that activated the transcription of CsLOX7, CsAOS2, CsPER1 and CsPER3 via bound with their promoters, respectively. Suppression of CsMYC2 expression resulted in a reduced JA content and peroxidase activity and osmotic stress tolerance of tea plant. Overexpression of CsMYC2 in Arabidopsis improved JA content, peroxidase activity and plants tolerance against mannitol stress. Together, we proposed a positive feedback loop mediated by CsMYC2, CsLOX7 and CsAOS2 which constituted to increase the tolerance of osmotic stress through fine-tuning the accumulation of JA levels and increase of POD activity in tea plant.

Core chlorophytes possess glycerol-3-phosphate dehydrogenases (GPDs) with an unusual bidomain structure, consisting of a glycerol-3-phosphate phosphatase (GPP) domain fused to canonical GPD domains. These plastid-localized enzymes have been implicated in stress responses, being required for the synthesis of glycerol under high salinity and triacylglycerols under nutrient deprivation. However, their regulation under varying environmental conditions is poorly understood. C. reinhardtii transgenic strains expressing constitutively bidomain GPD2 did not accumulate glycerol or triacylglycerols in the absence of any environmental stress. Although the glycerol contents of both wild type and transgenic strains increased significantly upon exposure to high salinity, cycloheximide, an inhibitor of cytoplasmic protein synthesis, abolished this response in the wild type. In contrast, GPD2 transgenic strains were still capable of glycerol accumulation when cultured in medium containing cycloheximide and NaCl. Thus, the pre-existing GPD2 protein appears to become activated for glycerol synthesis upon salt stress. Interestingly, staurosporine, a non-specific inhibitor of protein kinases, prevented this post-translational GPD2 protein activation. Structural modeling analyses suggested that substantial conformational rearrangements, possibly triggered by high salinity, may characterize an active GPD2 GPP domain. Understanding this mechanism(s) may provide insights into the rapid acclimation responses of microalgae to osmotic/salinity stress.

Subclass III sucrose nonfermenting1-related protein kinase 2s (SnRK2s) function in ABA and abiotic stress responses by unknown mechanisms. We found that osmotic stress/ABA-activated protein kinase 10 (SAPK10), a member of rice SnRK2s, physically interacted with CBL-interacting protein kinase 1 (OsCIPK1). OsCIPK1 expression was up-regulated by ABA and PEG treatment, and overexpression increased the ABA sensitivity of seed germination and root growth and plant osmotic stress tolerance. Osmotic stress or ABA-induced activation of OsCIPK1 is dependent on SAPK10. SAPK10 phosphorylates Thr-24 of OsCIPK1 in vitro, and this phosphorylation increases the activity of OsCIPK1 and positively regulates the function of OsCIPK1 in ABA responses and plant osmotic stress tolerance. This study suggests that OsCIPK1 is a direct phosphorylated substrate of SAPK10, and SAPK10-mediated phosphorylation of OsCIPK1 functions in ABA signaling and increases rice osmotic stress tolerance.

Cell‐specific transcriptional regulatory networks (TRNs) play vital roles in plant development and response to environmental stresses. However, traditional single‐cell mono‐omics techniques are unable to directly capture the relationships and dynamics between different layers of molecular information within the same cells. While advanced algorithm facilitates merging scRNA‐seq and scATAC‐seq datasets, accurate data integration remains a challenge, particularly when investigating cell‐type‐specific TRNs. By examining gene expression and chromatin accessibility simultaneously in 16,670 Arabidopsis root tip nuclei, the TRNs are reconstructed that govern root tip development under osmotic stress. In contrast to commonly used computational integration at cell‐type level, 12,968 peak‐to‐gene linkage is captured at the bona fide single‐cell level and construct TRNs at an unprecedented resolution. Furthermore, the unprecedented datasets allow to more accurately reconstruct the coordinated changes of gene expression and chromatin states during cellular state transition. During root tip development, chromatin accessibility of initial cells precedes gene expression, suggesting that changes in chromatin accessibility may prime cells for subsequent differentiation steps. Pseudo‐time trajectory analysis reveal that osmotic stress can shift the functional differentiation of trichoblast. Candidate stress‐related gene‐linked cis‐regulatory elements (gl‐cCREs) as well as potential target genes are also identified, and uncovered large cellular heterogeneity under osmotic stress. [ABSTRACT FROM AUTHOR]

Introduction: The ongoing global expansion of salt-affected land is a significant factor, limiting the growth and yield of crops, particularly rice (Oryza sativa L). This experiment explores the mitigation of salt-induced damage in rice (cv BRRI dhan100) following the application of plant growth-promoting rhizobacteria (PGPR). Methods: Rice seedlings, at five- and six-weeks post-transplanting, were subjected to salt stress treatments using 50 and 100 mM NaCl at seven-day intervals. Bacterial cultures consisting of endophytic PGPR (Bacillus subtilis and B. aryabhattai) and an epiphytic PGPR (B. aryabhattai) were administered at three critical stages: transplantation of 42-day-old seedlings, vegetative stage at five weeks post-transplantation, and panicle initiation stage at seven weeks post-transplantation. Discussion: These findings highlight the potential of PGPR to bolster physiological and biochemical functionality in rice by serving as an effective buffer against salt stress-induced damage. B. subtilis showed the greatest benefits, while both the endophytic and epiphytic B. aryabhattai had commendable effects in mitigating salt stress-induced damage in rice plants. Results: Salt stress induced osmotic stress, ionic imbalances, and oxidative damage in rice plants, with consequent negative effects on growth, decrease in photosynthetic efficiency, and changes in hormonal regulation, along with increased methylglyoxal (MG) toxicity. PGPR treatment alleviated salinity effects by improving plant antioxidant defenses, restoring ionic equilibrium, enhancing water balance, increasing nutrient uptake, improving photosynthetic attributes, bolstering hormone synthesis, and enhancing MG detoxification. [ABSTRACT FROM AUTHOR]

Seed coat mucilage plays an important role in promoting seed germination under adversity. Previous studies have shown that Arabidopsis thaliana MYB52 (AtMYB52) can positively regulate seed coat mucilage accumulation. However, the role of Brassica napus MYB52 (BnaMYB52) in accumulation of seed coat mucilage and tolerance to osmotic stress during seed germination remains largely unknown.We cloned the BnaA09.MYB52 coding domain sequence from B. napus cv ZS11, identified its conserved protein domains and elucidated its relationship with homologues from a range of plant species. Transgenic plants overexpressing BnaA09.MYB52 in the A. thaliana myb52‐1 mutant were generated through Agrobacterium‐mediated transformation and used to assess the possible roles of BnaA09.MYB52 in accumulation of seed coat mucilage and tolerance to osmotic stress during seed germination.Subcellular localization and transcriptional activity assays demonstrated that BnaA09.MYB52 functions as a transcription factor. RT‐qPCR results indicate that BnaA09.MYB52 is predominantly expressed in roots and developing seeds of B. napus cv ZS11. Introduction of BnaA09.MYB52 into myb52‐1 restored thinner seed coat mucilage in this mutant to levels in the wild type. Consistently, expression levels of three key genes participating in mucilage formation in developing seeds of myb52‐1 were also restored to wild type levels by overexpressing BnaA09.MYB52. Furthermore, BnaA09.MYB52 was induced by osmotic stress during seed germination in B. napus, and ectopic expression of BnaA09.MYB52 successfully corrected sensitivity of the myb52‐1 mutant to osmotic stress during seed germination.These findings enhance our understanding of the functions of BnaA09.MYB52 and provide a novel strategy for future B. napus breeding. [ABSTRACT FROM AUTHOR]

Despite soil salinity is one of the prime abiotic stresses, exploiting the saline soils for the agricultural production will increase in the forthcoming decades to fulfill the human food requirements. Of course, the induction of crop tolerance to salt stress will share in plant growth enhancement and keeping productivity. The current study aimed to assess the influence of soil amendments (gypsum, GP and humic acid, HA) and vitamin B6 (pyridoxine-HCl), levels on growth, yield traits and bioactive compounds of coriander plants grown in salt-affected soil. GP and HA, whether individual or in combination, at a rate of 500 and 20 kg/ha, respectively, were applied under spraying of B6 at three levels of at 0.0, 150, 300 µM. The experiment was performed in a strip-plot arrangement under randomized complete blocks design using three replications. Findings illustrated the increases in umbels number/plant, umblets number/plant, seed counts/umbels, and seed yield/plant due to applying GP + HA × B6-leafy applied at 300 µM were 150.3, 117.9, 157.4, and 237.8%, respectively. GP + HA mixture with spraying 300 µM B6 possessed the lowest values of H2O2 and malondialdehyde (by 1.78 and 0.12 µmol/g FW, orderly), in relative to the control. As well, the highest significant percentages of TSS, SPC, FAA, and FProC were obtained from the combination of GP + HA mixture × 300 µM B6. Coriander plants received 300 µM B6 and amended with GP + HA mixture gave the greatest N, P and K+ and the lowest Na+ contents. Briefly, cultivating coriander plants in salty soils requires compatible agricultural practices via soil amendments plus exogenous application of vitamins. Herein, soil addition of gypsum + humic acid with foliar application of vitamin B6 could be a recommended practice in managing coriander production under saline soil conditions. [ABSTRACT FROM AUTHOR]

Lipoic acid (LA), a unique antioxidant compound, can stimulate the antioxidant defense system in plants subjected to abiotic stresses. We aimed to determine the role of LA in induction of the antioxidant system at lower reactive oxygen species (ROS), ascorbate (ASC) and glutathione (GSH) levels in osmotic-stressed maize (Zea mays L.). For this purpose, ROS, GSH and ASC contents were decreased using N,N'‑dimethylthiourea (DMTU), L-buthionine sulfoximine (BSO) and acriflavine (AF), respectively. Pots containing 21-day-old seedlings were divided into nine groups consisting of a non-stressed group; polyethylene glycol6000 (PEG)-induced osmotic stress (PEG) group, LA, DMTU, BSO and AF treatment groups; and DMTU, BSO, and AF-combined LA treatment groups under osmotic stress. ROS contents and membrane damage after the DMTU, BSO, and AF-combined LA treatments were lower than those after the DMTU, BSO, and AF treatments, respectively. Moreover, the LA treatments in combination with DMTU, BSO and AF increased dry weight, activities of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase and dehydroascorbate reductase), and contents of GSH, ASC, and LA compared to the DMTU, BSO and AF treatments. Additionally, the relative expression levels of SUPEROXIDE DISMUTASE, CATALASE1 and ASCORBATE PEROXIDASE1 genes were consistent with the findings for their related antioxidant enzyme activities. These results indicated that LA could adjust ROS level and maintain stimulation of the antioxidant system at lower ROS, GSH, and ASC levels in osmotic stressed maize. Furthermore, LA may play a signaling role and assume the function of ASC and GSH in maize under PEG-induced osmotic stress. [ABSTRACT FROM AUTHOR]

Candida tropicalis is a human pathogen and one of the most prevalent non-Candida albicans Candida (NCAC) species causing invasive infections. Azole antifungal resistance in C. tropicalis is also gradually increasing with the increasing incidence of infections. The pathogenic success of C. tropicalis depends on its effective response in the host microenvironment. To become a successful pathogen, cellular metabolism, and physiological status determine the ability of the pathogen to counter diverse stresses inside the host. However, to date, limited knowledge is available on the impact of carbon substrate metabolism on stress adaptation and azole resistance in C. tropicalis. In this study, we determined the impact of glucose, fructose, and sucrose as the sole carbon source on the fluconazole resistance and osmotic (NaCl), oxidative (H2O2) stress adaptation in C. tropicalis clinical isolates. We confirmed that the abundance of carbon substrates influences or increases drug resistance and osmotic and oxidative stress tolerance in C. tropicalis. Additionally, both azole-resistant and susceptible isolates showed similar stress adaptation phenotypes, confirming the equal efficiency of becoming successful pathogens irrespective of drug susceptibility profile. To the best of our knowledge, our study is the first on C. tropicalis to demonstrate the direct relation between carbon substrate metabolism and stress tolerance or drug resistance. [ABSTRACT FROM AUTHOR]

The physicochemical properties of the cellular environment impact on the biochemical and molecular functions of plant cells. Osmotic stress conditions cause severe changes in intracellular macromolecular crowding that plants must adapt to for survival. Recent work has demonstrated that plant cells have mechanisms to sense changes in macromolecular crowding, including plasma membrane and intracellular osmosensors. Tools to dynamically track changes in macromolecular crowding will further contribute to the identification of plant osmosensors. Osmotic stress conditions occur at multiple stages of plant life. Changes in water availability caused by osmotic stress induce alterations in the mechanical properties of the plasma membrane, its interaction with the cell wall, and the concentration of macromolecules in the cytoplasm. We summarize the reported players involved in the sensing mechanisms of osmotic stress in plants. We discuss how changes in macromolecular crowding are perceived intracellularly by intrinsically disordered regions (IDRs) in proteins. Finally, we review methods for dynamically monitoring macromolecular crowding in living cells and discuss why their implementation is required for the discovery of new plant osmosensors. Elucidating the osmosensing mechanisms will be essential for designing strategies to improve plant productivity in the face of climate change. [ABSTRACT FROM AUTHOR]

Current environmental changes can drastically affect aquatic freshwater ecosystems. Salinization is one such change that affects freshwater species due to osmotic costs, which induce a wide variety of behavioural responses, including altered response to predation. This is particularly important in larval anurans, known to modulate their morphology, physiology and behaviour in response to salinity. Although these responses are known for long-term exposure, the effects of shorter exposure to salinity, relevant for coastal biodiversity as a result of sea water intrusions and precipitation variation, have rarely been assessed despite their importance in understanding the speed at which impacts on biodiversity occur. In this study, we experimentally acclimated larvae of the spined toad, Bufo spinosus , for 2 weeks to freshwater or to moderate levels of salinity (4 g/litre). The response to predation, activity and spatial movements of each individual were then assessed both at the salinity of acclimation and after a change in salinity. We demonstrated that medium-term exposure to salinity decreased activity, decreased growth and increased mortality. In contrast, sudden changes in salinity increased the escape distance of tadpoles in response to a predation stimulus but decreased activity. These results suggest that exposure to both stressors (predation cues and varying salinities) led to increased activity presumably linked to a stress response. However, individuals exposed to a change in salinity or to moderate salinity for medium durations expressed similar behavioural responses, indicating that the detrimental effects of high salinity can occur rapidly. Future studies should investigate the dynamics of osmolality in larval anurans exposed to brackish water to assess whether these behavioural shifts are linked with hydromineral dysregulation, and how long after exposure this occurs. • Two weeks exposure to salinity reduced tadpole growth and activity. • Transfer to freshwater did not improve activity levels. • Transfer to high salinity altered behaviour in less than 1 h. • Sudden increase in salinity led to increased escape distance from predators. • Sudden changes in salinity led to decreased overall activity. [ABSTRACT FROM AUTHOR]

Core chlorophytes possess glycerol-3-phosphate dehydrogenases (GPDs) with an unusual bidomain structure, consisting of a glycerol-3-phosphate phosphatase (GPP) domain fused to canonical GPD domains. These plastid-localized enzymes have been implicated in stress responses, being required for the synthesis of glycerol under high salinity and triacylglycerols under nutrient deprivation. However, their regulation under varying environmental conditions is poorly understood. C. reinhardtii transgenic strains expressing constitutively bidomain GPD2 did not accumulate glycerol or triacylglycerols in the absence of any environmental stress. Although the glycerol contents of both wild type and transgenic strains increased significantly upon exposure to high salinity, cycloheximide, an inhibitor of cytoplasmic protein synthesis, abolished this response in the wild type. In contrast, GPD2 transgenic strains were still capable of glycerol accumulation when cultured in medium containing cycloheximide and NaCl. Thus, the pre-existing GPD2 protein appears to become activated for glycerol synthesis upon salt stress. Interestingly, staurosporine, a non-specific inhibitor of protein kinases, prevented this post-translational GPD2 protein activation. Structural modeling analyses suggested that substantial conformational rearrangements, possibly triggered by high salinity, may characterize an active GPD2 GPP domain. Understanding this mechanism(s) may provide insights into the rapid acclimation responses of microalgae to osmotic/salinity stress. [ABSTRACT FROM AUTHOR]

Drought stress has been extensively studied for its effect on the downstream signaling cascade and stress-responsive gene expression, but understanding the process has remained elusive. Recently, Zhao et al. identified DROOPY LEAF1 (DPY1) as an osmosensor and revealed a novel mechanism of DPY1-STRESS ACTIVATED PROTEIN KINASE6 (SAPK6)-mediated drought stress signaling in higher plants. [ABSTRACT FROM AUTHOR]

GRAS family is a plant-specific transcription factor, which plays an important role in regulating plant growth and development and responding to stresses. Exploring the function of GRAS family genes in maize (Zea mays L.) provides the important genetic resources for the creation of new maize germplasm. In this study, ZmGRAS13 gene (Zm00001eb401210) was cloned, and its basic characteristics, tissue expression characteristics, and the relative expression patterns under stresses were analyzed by bioinformatics and qRT-PCR. Bioinformatics showed that the full-length coding sequence of this gene was 1638 bp, encoding 545 amino acids. ZmGRAS13 protein had no transmembrane structure, and the molecular weight of 60.79 kD, the theoretical isoelectric point of 5.86, and had a conserved domain unique to the GRAS family. The analysis of 2 kb sequence upstream of the gene promoter indicated that the sequence contained cis-acting elements related to stresses, hormone response, and light response. The qRT-PCR analysis showed that ZmGRAS13 gene was expressed in different tissues of maize, and the relative expression level in stem was the highest. At the same time, the gene has different degrees of induced expression under different abiotic stress treat- ment conditions. The transient expression experiment of maize protoplasts demonstrated that ZmGRAS13 protein was localized in the nucleus. On 1/2 MS solid medium containing different concentrations of NaCl, mannitol, abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA), respectively, the root length of ZmGRAS13 transgenic Arabidopsis lines was significantly longer than the control. In the soil, transgenic Arabidopsis lines grew better than the control under high salt and drought treatments, and the green leaf rate was higher than the control. Compared with the wild type, the content of stress resistance physiological index MDA decreased, the chlorophyll content increased, and the activities of POD and CAT increased in the transgenic ZmGRAS13 Arabidopsis thaliana, and the difference was significant difference. In conclusion, ZmGRAS13 gene may be involved in the regulation of maize growth and development, response to stresses and hormone signal transduction pathway. This study provides an important reference for the further analysis of the biological function of ZmGRAS13 in maize. [ABSTRACT FROM AUTHOR]

Leucine-rich repeat extensin (LRX) is involved in the regulation of crucial cellular processes, such as cell wall growth and development, as well as signaling. However, the presence of the LRX gene family in Brassica rapa (B. rapa) has not been previously reported. This study identified 17 BrLRXs within the Brassica rapa genome by bioinformatic analysis, and these genes were distributed on seven chromosomes. Phylogenetic and covariance analyses indicate that BrLRXs can be categorized into two distinct branches: the trophic branch and the reproductive branch, with a close relationship observed between BrLRXs and AtLRXs. According to cis-acting element analysis, this gene family is rich in hormone-responsive and stress-responsive elements such as drought-inducibility, abscisic acid, methyl jasmonate, and gibberellic acid responsive elements, suggesting a potential role in abiotic stress response. Transcriptomic, proteomic, and RT-qPCR analyses demonstrated significant up-regulation of BrLRX2 and BrLRX6 under salt stress, while BrLRX3, BrLRX6, and BrLRX8 were significantly down-regulated under osmotic stress. Our analysis of the protein tertiary structure predicts a strong association between LRX proteins and RALF. Protein–protein interaction prediction revealed that LRX interacts with the RALF protein and the receptor FER, which have been previously reported to jointly regulate plant stress responses. We propose that BrLRX6 and BrLRX8 are implicated in osmotic stress, while BrLRX2 and BrLRX6 are involved in the modulation of salt stress. [ABSTRACT FROM AUTHOR]

Lysosomes are central players in cellular catabolism, signaling, and metabolic regulation. Cellular and environmental stresses that damage lysosomal membranes can compromise their function and release toxic content into the cytoplasm. Here, we examine how cells respond to osmotic stress within lysosomes. Using sensitive assays of lysosomal leakage and rupture, we examine acute effects of the osmotic disruptant glycyl-L-phenylalanine 2-naphthylamide (GPN). Our findings reveal that low concentrations of GPN rupture a small fraction of lysosomes, but surprisingly trigger Ca2+ release from nearly all. Chelating cytoplasmic Ca2+ makes lysosomes more sensitive to GPN-induced rupture, suggesting a role for Ca2+ in lysosomal membrane resilience. GPN-elicited Ca2+ release causes the Ca2+-sensor Apoptosis Linked Gene-2 (ALG-2), along with Endosomal Sorting Complex Required for Transport (ESCRT) proteins it interacts with, to redistribute onto lysosomes. Functionally, ALG-2, but not its ESCRT binding-disabled ΔGF122 splice variant, increases lysosomal resilience to osmotic stress. Importantly, elevating juxta-lysosomal Ca2+ without membrane damage by activating TRPML1 also recruits ALG-2 and ESCRTs, protecting lysosomes from subsequent osmotic rupture. These findings reveal that Ca2+, through ALG-2, helps bring ESCRTs to lysosomes to enhance their resilience and maintain organelle integrity in the face of osmotic stress. [ABSTRACT FROM AUTHOR]

Globally, drought stress poses a significant threat to crop productivity. Improving the drought tolerance of crops with microbial biostimulants is a sustainable strategy to meet a growing population's demands. This research aimed to elucidate microbial biostimulants' (Plant Growth Promoting Rhizobacteria) role in alleviating drought stress in oil-seed crops. In total, 15 bacterial isolates were selected for drought tolerance and screened for plant growth-promoting (PGP) attributes like phosphate solubilization and production of indole-3-acetic acid, siderophore, hydrogen cyanide, ammonia, and exopolysaccharide. This research describes two PGPR strains: Acinetobacter calcoaceticus AC06 and Bacillus amyloliquefaciens BA01. The present study demonstrated that these strains (AC06 and BA01) produced abundant osmolytes under osmotic stress, including proline (2.21 and 1.75 µg ml− 1), salicylic acid (18.59 and 14.21 µg ml− 1), trehalose (28.35 and 22.74 µg mg− 1 FW) and glycine betaine (11.35 and 7.74 mg g− 1) respectively. AC06 and BA01 strains were further evaluated for their multifunctional performance by inoculating in Arachis hypogaea L. (Groundnut) under mild and severe drought regimes (60 and 40% Field Capacity). Inoculation with microbial biostimulants displayed distinct osmotic-adjustment abilities of the groundnut, such as growth parameters, plant biomass, photosynthetic pigments, relative water content, proline, and soluble sugar in respective to control during drought. On the other hand, plant sensitivity indexes such as electrolyte leakage and malondialdehyde (MDA) contents were decreased as well as cooperatively conferred plant drought tolerance by induced alterations in stress indicators such as catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD). Thus, Acinetobacter sp. AC06 and Bacillus sp. BA01 can be considered as osmolyte producing microbial biostimulants to simultaneously induce osmotic tolerance and metabolic changes in groundnuts under drought stress. [ABSTRACT FROM AUTHOR]

The co-existence of drought and salinity stresses due to rapid global climate change is detrimental to plants. Both stress conditions alter the morpho-physiological, biochemical, and molecular responses of plants due to ionic toxicity, osmotic, hormonal, and nutrient imbalance, and oxidative stress. In general, the combination of both stresses is worse for plants rather than an individual stress condition. To date, various novel strategies including the use of nanoparticles (NPs) have been tried to minimize the negative effects of these stresses. Despite various interventions, improvements are still needed to create tolerance against the combined stress of drought and salinity using NPs in plants. The application of NPs regulates various plant defense mechanisms such as the activation of antioxidative mechanisms to detoxification of reactive oxygen species (ROS) and effectively interferes with gene expression and cellular mechanisms to protect the plant cells. Here, we present an overview of how these stresses are deleterious for plants' health and discuss the potential mechanisms underlying NPs-induced tolerance against drought and salinity conditions. [ABSTRACT FROM AUTHOR]

Background: Drought is a critical limiting factor affecting the growth and development of spring maize (Zea mays L.) seedlings in northeastern China. Sodium 5-nitroguaiacol (5-NGS) has been found to enhance plant cell metabolism and promote seedling growth, which may increase drought tolerance. Methods: In the present study, we investigated the response of maize seedlings to foliar application of a 5-NGS solution under osmotic stress induced by polyethylene glycol (PEG-6000). Four treatment groups were established: foliar application of distilled water (CK), foliar application of 5-NGS (NS), osmotic stress + foliar application of distilled water (D), and osmotic stress + foliar application of 5-NGS (DN). Plant characteristics including growth and photosynthetic and antioxidant capacities under the four treatments were evaluated. Results: The results showed that under osmotic stress, the growth of maize seedlings was inhibited, and both the photosynthetic and antioxidant capacities were weakened. Additionally, there were significant increases in the proline and soluble sugar contents and a decrease in seedling relative water content (RWC). However, applying 5-NGS alleviated the impact of osmotic stress on maize seedling growth parameters, particularly the belowground biomass, with a dry mass change of less than 5% and increased relative water content (RWC). Moreover, treatment with 5-NGS mitigated the inhibition of photosynthesis caused by osmotic stress by restoring the net photosynthetic rate (Pn) through an increase in chlorophyll content, photosynthetic electron transport, and intercellular CO2 concentration (Ci). Furthermore, the activity of antioxidant enzymes in the aboveground parts recovered, resulting in an approximately 25% decrease in both malondialdehyde (MDA) and H2O2. Remarkably, the activity of enzymes in the underground parts exhibited more significant changes, with the contents of MDA and H2O2 decreasing by more than 50%. Finally, 5-NGS stimulated the dual roles of soluble sugars as osmoprotectants and energy sources for metabolism under osmotic stress, and the proline content increased by more than 30%. We found that 5-NGS played a role in the accumulation of photosynthates and the effective distribution of resources in maize seedlings. Conclusions: Based on these results, we determined that foliar application of 5-NGS may improve osmotic stress tolerance in maize seedlings. This study serves as a valuable reference for increasing maize yield under drought conditions. [ABSTRACT FROM AUTHOR]

Drought is a major stress affecting rice yields. Combining partial root-zone drying (PRD) and different nitrogen fertilizers reduces the damage caused by water stress in rice. However, the underlying molecular mechanisms remain unclear. In this study, we combined treatments with PRD and ammonia:nitrate nitrogen at 0:100 (PRD0:100) and 50:50 (PRD50:50) ratios or PEG and nitrate nitrogen at 0:100 (PEG0:100) ratios in rice. Physiological, transcriptomic, and metabolomic analyses were performed on rice leaves to identify key genes involved in water stress tolerance under different nitrogen forms and PRD pretreatments. Our results indicated that, in contrast to PRD0:100, PRD50:50 elevated the superoxide dismutase activity in leaves to accelerate the scavenging of ROS accumulated by osmotic stress, attenuated the degree of membrane lipid peroxidation, stabilized photosynthesis, and elevated the relative water content of leaves to alleviate the drought-induced osmotic stress. Moreover, the alleviation ability was better under PRD50:50 treatment than under PRD0:100. Integrated transcriptome and metabolome analyses of PRD0:100 vs PRD50:50 revealed that the differences in PRD involvement in water stress tolerance under different nitrogen pretreatments were mainly in photosynthesis, oxidative stress, nitrogen metabolism process, phytohormone signaling, and biosynthesis of other secondary metabolites. Some key genes may play an important role in these pathways, including OsGRX4, OsNDPK2, OsGS1;1, OsNR1.2, OsSUS7, and YGL8. Thus, the osmotic stress tolerance mediated by PRD and nitrogen cotreatment is influenced by different nitrogen forms. Our results provide new insights into osmotic stress tolerance mediated by PRD and nitrogen cotreatment, demonstrate the essential role of nitrogen morphology in PRD-induced molecular regulation, and identify genes that contribute to further improving stress tolerance in rice. [ABSTRACT FROM AUTHOR]

Jasmonates are involved in the regulation of protective mechanisms of plants against unfavorable environments as well as in control of their growth and development. Main data on jasmonate biosynthesis and signals transduction pathways were obtained on model dicotyledonous plant Arabidopsis thaliana. Meanwhile, functions and molecular mode of action of these compounds are still poorly investigated in monocotyledons, including wheat. In the present study, the stress tolerance of transgenic line (Tr-3) and nontransgenic plants of bread wheat cv. Saratovskaya-60 was studied. Transgenic line Tr-3 overexpresses AtOPR3 (12-OXOPHYTODIENOATE REDUCTASE 3) gene from A. thaliana encoding the jasmonate biosynthesis enzyme 12-oxophytodienoate reductase. In spite of the high expression level of AtOPR3, the content of jasmonic acid and its conjugate with isoleucine in intact leaves of the transgenic plants remained unchanged. Furthermore, in the mechanically wounded leaves, the content of jasmonic acid in the transgenic line Tr-3 was even lower than in nontransgenic Saratovskaya-60, while the levels of 12-oxophytodienoic acid and jasmonoil-isoleucine did not differ. In the transgenic plants, the stress-induced expression of the endogenous jasmotate-regulated allene oxide synthase gene was, however, higher than in the nontransgenic control. The transgenic wheat plants were more tolerant to infection by necrotrophic fungus Botrytis cinerea and to osmotic stress caused by polyethylene glycol applied to germinating seeds. The Botrytis-inoculated leaves of the transgenic line Tr-3 manifested higher activity of antioxidant enzyme catalase than inoculated leaves of nontransgenic plants. This fact points to the possible role of catalase in the transgene-associated tolerance to the pathogen. Therefore, the available scarce information concerning the peculiarities of functions of the jasmonate system in wheat plants has been amended with the new data on the role of expression of one of the key genes of jasmonate biosynthesis, namely, 12-OXOPHYTODIENOATE REDUCTASE, in control of defense responses even though the stress-induced level of jasmonic acid is decreased. [ABSTRACT FROM AUTHOR]

Objective: Methicillin-resistant Staphylococcus aureus (MRSA) is a clinically common and has a high mortality rate pathogen, as well as a bacterium that causes infection through food. To combat with pathogens, it is commonly preferred to create osmotic stress in their environment but S. aureus is able to synthesize some osmoprotectant substances such as betaine. There is limited literature about the synthesis pathways and gene expressions of these substances. This study aims to search the metabolic pathways of osmoprotectan production of S. aureus by comparing the bacterial behaviour with the expression of genes responsible for betaine. Methods: In the current study, different concentrations of NaCl and KCl salts (0.5, 1.0, 1.5, 2.0 and 3.0 M) were applied to Staphylococcus aureus ATCC 43300, changes in the number of viable cells of the bacteria were monitored and associated with osmoprotectant production. Bacterial numbers treated with salt were counted by culturel and spectrophotometric methods and viability graphs were created. Simultaneously, metabolic pathways under stress conditions were determined by monitoring the expression of genes responsible for betaine in RT-PCR. Results: When the growth curve of the bacterium is examined in NaCl or KCl salt stress, it was observed that the bacteria exited the logarithmic phase and was more affected by the stress conditions, especially at 12-24 time interval which is critical in the development of bacteria. The most notable results in the RT-PCR trials of the study were obtained when 1.5 M NaCl was present in the growth media at 36th hour of incubation. Under these conditions, a significant decrease of (-2.37-fold) in the betA gene was observed. Contrary to this result, 2.57-fold increase in the betA gene and 3.25-fold increase in the betB-gbsA gene was observed when 2 M KCl was present in the medium at 48th hour of incubation. Conclusion: During the 48-hour incubation period in which the bacterial growth was followed, it was observed that the bacteria exhibited a fluctuating growth curve against the salt stress and exhibited a different behavior than expected in the growth kinetics. [ABSTRACT FROM AUTHOR]

Investigating the effects of priming methods on seedling physiology under osmotic stress conditions is important to understand how priming enhances osmotic stress tolerance in safflower. The mechanisms by which priming achieves this at the physiological level, such as changes in osmoprotectants, antioxidants, and membrane damage, are not well understood. This research aims to fill these knowledge gaps and provide insights that can be used to optimize priming treatments and improve safflower productivity in drought-prone areas.. Seeds were treated with priming including distilled water, folic acid, glutathione, epibrassinolide and chitosan and then subjected to osmotic stresses including no osmotic stress, mild osmotic stress (4 bar) and severe osmotic stress (8 bar) for germination and seedling growth. Severe osmotic stress increased soluble leaf proteins, this increase was observed in all priming treatments except distilled water. Severe osmotic stress increased soluble leaf proteins by an average of 35% in folic acid, chitosan, and epibrassinolide treatments. Chitosan treatment exhibited 172% and 188% more proline under mild and severe stress, respectively, compared to the control. Folic acid treatment showed a 207% increase in catalase under severe stress. Epibrassinolide and glutathione treatments had 201% more superoxide dismutase (SOD) under non-stress conditions. Distilled water treatment had 48.6% more soluble sugars under non-stress, while glutathione and epibrassinolide treatments had 14.5% more under mild stress. Control treatment had the highest malondialdehyde (MDA) amounts under mild and severe stress. Chitosan treatment exhibited a 25% increase in seedling length under severe stress compared to the control. Under non-stress conditions, chitosan treatment had slightly lower seedling length compared to control, while glutathione and epibrassinolide treatments showed the highest lengths. Under mild stress, folic acid, chitosan, and epibrassinolide treatments were superior to control. Under severe stress, distilled water showed a 20% increase, while chitosan treatment showed a 25% increase in seedling length compared to control. Chitosan treatment improved safflower seedling growth under severe osmotic stress through mechanisms including increased osmoprotectant levels, enhanced antioxidant activity, and improved membrane integrity. [ABSTRACT FROM AUTHOR]

We investigated bile salts' ability to induce phenotypic changes in biofilm production and protein expression of pathogenic Escherichia coli strains. For this purpose, 82 pathogenic E. coli strains isolated from humans (n  = 70), and animals (n  = 12), were examined for their ability to form biofilms in the presence or absence of bile salts. We also identified bacterial proteins expressed in response to bile salts using sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-electrophoresis) and liquid chromatography-mass spectrometry (LC-MS/MS). Lastly, we evaluated the ability of these strains to adhere to Caco-2 epithelial cells in the presence of bile salts. Regarding biofilm formation, two strains isolated from an outbreak in Republic of Georgia in 2009 were the only ones that showed a high and moderate capacity to form biofilm in the presence of bile salts. Further, we observed that those isolates, when in the presence of bile salts, expressed different proteins identified as outer membrane proteins (i.e. OmpC), and resistance to adverse growth conditions (i.e. F0F1, HN-S, and L7/L12). We also found that these isolates exhibited high adhesion to epithelial cells in the presence of bile salts. Together, these results contribute to the phenotypic characterization of E. coli O104: H4 strains. [ABSTRACT FROM AUTHOR]

Paraspeckles are nuclear condensates formed by NEAT1_2 lncRNA and different RNA-binding proteins. In general, these membraneless organelles function in the regulation of gene expression and translation and in miRNA processing, and in doing this, they regulate cellular homeostasis and mediate pro-survival in the cell. Despite evidence showing the importance of paraspeckles in the stress response, the dynamics of paraspeckles and their components under conditions of osmotic stress remain unknown. We exposed HEK293T cells to sorbitol and examined NEAT1_2 expression using real-time PCR. Localization and quantification of the main paraspeckle components, NEAT1_2, PSPC1, NONO, and SFPQ, in different cellular compartments was performed using smFISH and immunofluorescence. Our findings showed a significant decrease in total NEAT1_2 expression in cells after osmotic stress. Sorbitol shifted the subcellular localization of NEAT1_2, PSPC1, NONO, and SFPQ from the nucleus to the cytoplasm and decreased the number and size of NEAT1_2 foci in the nucleus. PSPC1 formed immunoreactive cytoplasmic fibrils under conditions of osmotic stress, which slowly disassembled under recovery. Our study deepens the paraspeckle dynamics in response to stress, suggesting a novel role for NEAT1_2 in the cytoplasm in osmotic stress and physiological conditions. [ABSTRACT FROM AUTHOR]

Lactic acid bacteria (LAB) hold significant importance in diverse fields, including food technology, industrial biotechnology, and medicine. As basic components of starter cultures, probiotics, immunomodulators, and live vaccines, LAB cells resist a variety of stressors, including temperature fluctuations, osmotic and pH shocks, exposure to oxidants and ultraviolet radiation, substrate deprivation, mechanical damage, and more. To stay alive in these adversities, LAB employ a wide range of stress response strategies supported by various mechanisms, for example rearrangement of metabolism, expression of specialized biomolecules (e.g., chaperones and antioxidants), exopolysaccharide synthesis, and complex repair and regulatory systems. LAB can coordinate responses to various stressors using global regulators. In this review, we summarize current knowledge about stress response strategies used by LAB and consider mechanisms of response to specific stressful factors, supported by illustrative examples. In addition, we discuss technical approaches to increase the stress resistance of LAB, including pre-adaptation, genetic modification of strains, and adjustment of cultivation conditions. A critical analysis of the recent findings in this field augments comprehension of stress tolerance mechanisms in LAB, paving the way for prospective research directions with implications in fundamental and practical areas. [ABSTRACT FROM AUTHOR]

Because of their shallow root system, drought stress is a major problem in potato cultivation. Due to climate change more severe drought periods are expected to occur in the vegetative growth phase of potato growth. Therefore, there is a great need for drought tolerant potato genotypes. Potato responds to drought stress in the field in various ways, including osmoregulation. Osmotic stress can be induced in vitro by adding an osmotic agent and thus lowering the osmotic potential of the medium. In this study, a new, cost-effective in vitro test system is presented, in which the osmotic agent can be gradually added after root formation to prevent an osmotic shock. This is achieved by using sieves as plant holders and liquid medium, which, allows an improved simulation of gradually drying soil. Responses to osmotic stress in four potato genotypes were analysed and an increase in proline under osmotic stress was detected. Moreover, genes of interest that were postulated to be linked to drought stress were shown by quantitative qRT-PCR to be regulated under osmotic stress. Furthermore, we showed that the content of sorbitol, which was used as osmotic agent, was 700- fold higher for ‘Eurostarch’ after seven days under osmotic stress and 1093- fold higher after 14 days, respectively, compared to control plants without sorbitol addition. Therefore, further investigations must show, whether it was taken up through the roots, is metabolised, stored or de novo synthesised by the potato plants. Keypoints: The established novel in vitro test system for potato allows gradually increasing stress exposition of rooted plants. Sorbitol seems not an ideal osmotic agent as it is likely taken up. [ABSTRACT FROM AUTHOR]

Exposure to mineral fibers represents an occupational and environmental hazard since particulate inhalation leads to several health disorders. However, few data are available on the effect of fibers with high solubility like natural epsomite, a water‐soluble fiber with an inhalable size that allows it to penetrate biological systems, with regard to the respiratory tract. This study evaluated the natural (fibrous epsomite) and synthetic (Epsom salt) magnesium sulfate pathogenicity. Investigations have been performed through morpho‐functional and biochemical analyses, in an in vitro cell model that usually grows as monocytes, but that under appropriate conditions differentiates into macrophages. These latter, known as alveolar macrophages, if referred to lungs, represent the first line of defense against harmful inhaled stimuli. Morphological observations reveal that, if Epsom salt induces osmotic stress on cell culture, natural epsomite fibers lead to cellular alterations including thickening of the nuclear envelope and degenerated mitochondria. Moreover, the insoluble fraction (impurities) internalized by cells induces diffuse damage characterized at the highest dosage and exposure time by secondary necrosis or necrotic cell death features. Biochemical analyses confirm this mineral behavior that involves MAPK pathway activation, resulting in many different cellular responses ranging from proliferation control to cell death. Epsom salt leads to MAPK/ERK activation, a marker predictive of overall survival. Unlike, natural epsomite induces upregulation of MAPK/p38 protein involved in the phosphorylation of downstream targets driving necrotic cell death. These findings demonstrate natural epsomite toxicity on U937 cell culture, making the inhalation of these fibers potentially hazardous for human health. Research Highlights: Natural epsomite and synthetic Epsom salt effects have been evaluated in U937 cell model.Epsom salt induces an osmotic cellular stress.Natural epsomite fibers lead to cellular damage and can be considered potentially dangerous for human health. [ABSTRACT FROM AUTHOR]

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Abstract The objective of this work was to evaluate the effects of saline and water stresses on the germination of seeds and of saline stress on the development of seedlings of 'SCS437 Catarina' Passiflora edulis. The seeds were germinated on paper moistened with NaCl and PEG 6,000 solutions, at the osmotic potentials of 0.00, −0.25, −0.50, −0.75, −1.00, and −2.00 MPa. The produced seedlings were exposed only to NaCl. The seeds show tolerance to saline stress up to an osmotic potential of −0.75 MPa, while the seedlings present tolerance up to an osmotic potential of −0.50 MPa (10.96 mS cm−1).

ABSTRACT The Saccharomyces cerevisiae DOG genes, DOG1 and DOG2, encode for 2-deoxyglucose-6-phosphate phosphatases. These enzymes of the haloacid dehalogenase superfamily are known to utilize the non-natural 2-deoxyglucose-6-phosphate as their substrate. However, their physiological substrate and hence their biological role remain elusive. In this study, we investigated their potential role as enzymes in biosynthesizing glycerol through an alternative pathway, which involves the dephosphorylation of dihydroxyacetone phosphate into dihydroxyacetone, as opposed to the classical pathway which utilizes glycerol 3-phosphate. Overexpression of DOG1 or DOG2 rescued the osmotic and ionic stress-sensitive phenotype of gpp1∆ gpp2∆ or gpd1∆ gpd2∆ mutants, both affected in the production of glycerol. While small amounts of glycerol were observed in the DOG overexpression strains in the gpp1∆ gpp2∆ background, no glycerol was detected in the gpd1∆ gpd2∆ mutant background. This indicates that overexpression of the DOG enzymes can rescue the osmosensitive phenotype of the gpd1∆ gpd2∆ mutant independent of glycerol production. We also did not observe a drop in glycerol levels in the gpp1∆ gpp2∆ dog1∆ dog2∆ as compared to the gpp1∆ gpp2∆ mutant, indicating that the Dog enzymes are not involved in glycerol biosynthesis. This indicates that Dog enzymes have a distinct substrate and their function within the cell remains undiscovered.IMPORTANCEYeast stress tolerance is an important characteristic that is studied widely, not only regarding its fundamental insights but also for its applications within the biotechnological industry. Here, we investigated the function of two phosphatase encoding genes, DOG1 and DOG2, which are induced as part of the general stress response pathway, but their natural substrate in the cells remains unclear. They are known to dephosphorylate the non-natural substrate 2-deoxyglucose-6-phosphate. Here, we show that overexpression of these genes overcomes the osmosensitive phenotype of mutants that are unable to produce glycerol. However, in these overexpression strains, very little glycerol is produced indicating that the Dog enzymes do not seem to be involved in a previously predicted alternative pathway for glycerol production. Our work shows that overexpression of the DOG genes may improve osmotic and ionic stress tolerance in yeast.

Global climate change and the decreasing availability of high-quality water lead to an increase in the salinization of agricultural lands. This rising salinity represents a significant abiotic stressor that detrimentally influences plant physiology and gene expression. Consequently, critical processes such as seed germination, growth, development, and yield are adversely affected. Salinity severely impacts crop yields, given that many crop plants are sensitive to salt stress. Plant growth-promoting microorganisms (PGPMs) in the rhizosphere or the rhizoplane of plants are considered the “second genome” of plants as they contribute significantly to improving the plant growth and fitness of plants under normal conditions and when plants are under stress such as salinity. PGPMs are crucial in assisting plants to navigate the harsh conditions imposed by salt stress. By enhancing water and nutrient absorption, which is often hampered by high salinity, these microorganisms significantly improve plant resilience. They bolster the plant’s defenses by increasing the production of osmoprotectants and antioxidants, mitigating salt-induced damage. Furthermore, PGPMs supply growth-promoting hormones like auxins and gibberellins and reduce levels of the stress hormone ethylene, fostering healthier plant growth. Importantly, they activate genes responsible for maintaining ion balance, a vital aspect of plant survival in saline environments. This review underscores the multifaceted roles of PGPMs in supporting plant life under salt stress, highlighting their value for agriculture in salt-affected areas and their potential impact on global food security.

Abstract Drought-induced osmotic stress severely affects the growth and yield of maize. However, the mechanisms underlying the different responses of young and old maize leaves to osmotic stress remain unclear. To gain a systematic understanding of age-related stress responses, we compared osmotic-stress-induced changes in maize leaves of different ages using multi-omics approaches. After short-term osmotic stress, old leaves suffered more severe water deficits than young leaves. The adjustments of transcriptomes, proteomes, and hormones in response to osmotic stress were more dynamic in old leaves. Metabolic activities, stress signaling pathways, and hormones (especially abscisic acid) responded to osmotic stress in an age-dependent manner. We identified multiple functional clusters of genes and proteins with potential roles in stress adaptation. Old leaves significantly accumulated stress proteins such as dehydrin, aquaporin, and chaperones to cope with osmotic stress, accompanied by senescence-like cellular events, whereas young leaves exhibited an effective water conservation strategy mainly by hydrolyzing transitory starch and increasing proline production. The stress responses of individual leaves are primarily determined by their intracellular water status, resulting in differential transcriptomes, proteomes, and hormones. This study extends our understanding of the mechanisms underlying plant responses to osmotic stress.

Abstract Background The halophilic bacterium Halomonas elongata is an industrially important strain for ectoine production, with high value and intense research focus. While existing studies primarily delve into the adaptive mechanisms of this bacterium under fixed salt concentrations, there is a notable dearth of attention regarding its response to fluctuating saline environments. Consequently, the stress response of H. elongata to salt shock remains inadequately understood. Results This study investigated the stress response mechanism of H. elongata when exposed to NaCl shock at short- and long-time scales. Results showed that NaCl shock induced two major stresses, namely osmotic stress and oxidative stress. In response to the former, within the cell’s tolerable range (1–8% NaCl shock), H. elongata urgently balanced the surging osmotic pressure by uptaking sodium and potassium ions and augmenting intracellular amino acid pools, particularly glutamate and glutamine. However, ectoine content started to increase until 20 min post-shock, rapidly becoming the dominant osmoprotectant, and reaching the maximum productivity (1450 ± 99 mg/L/h). Transcriptomic data also confirmed the delayed response in ectoine biosynthesis, and we speculate that this might be attributed to an intracellular energy crisis caused by NaCl shock. In response to oxidative stress, transcription factor cysB was significantly upregulated, positively regulating the sulfur metabolism and cysteine biosynthesis. Furthermore, the upregulation of the crucial peroxidase gene (HELO_RS18165) and the simultaneous enhancement of peroxidase (POD) and catalase (CAT) activities collectively constitute the antioxidant defense in H. elongata following shock. When exceeding the tolerance threshold of H. elongata (1–13% NaCl shock), the sustained compromised energy status, resulting from the pronounced inhibition of the respiratory chain and ATP synthase, may be a crucial factor leading to the stagnation of both cell growth and ectoine biosynthesis. Conclusions This study conducted a comprehensive analysis of H. elongata’s stress response to NaCl shock at multiple scales. It extends the understanding of stress response of halophilic bacteria to NaCl shock and provides promising theoretical insights to guide future improvements in optimizing industrial ectoine production.

Abstract Alfalfa, an essential forage crop known for its high yield, nutritional value, and strong adaptability, has been widely cultivated worldwide. The yield and quality of alfalfa are frequently jeopardized due to environmental degradation. Lignin, a constituent of the cell wall, enhances plant resistance to abiotic stress, which often causes osmotic stress in plant cells. However, how lignin responds to osmotic stress in leaves remains unclear. This study explored the effects of osmotic stress on lignin accumulation and the contents of intermediate metabolites involved in lignin synthesis in alfalfa leaves. Osmotic stress caused an increase in lignin accumulation and the alteration of core enzyme activities and gene expression in the phenylpropanoid pathway. We identified five hub genes (CSE, CCR, CADa, CADb, and POD) and thirty edge genes (including WRKYs, MYBs, and UBPs) by integrating transcriptome and metabolome analyses. In addition, ABA and ethylene signaling induced by osmotic stress regulated lignin biosynthesis in a contradictory way. These findings contribute to a new theoretical foundation for the breeding of high-quality and resistant alfalfa varieties.

Abstract The deleterious impact of osmotic stress, induced by water deficit in arid and semi-arid regions, poses a formidable challenge to cotton production. To protect cotton farming in dry areas, it’s crucial to create strong plans to increase soil water and reduce stress on plants. The carboxymethyl cellulose (CMC), gibberellic acid (GA3) and biochar (BC) are individually found effective in mitigating osmotic stress. However, combine effect of CMC and GA3 with biochar on drought mitigation is still not studied in depth. The present study was carried out using a combination of GA3 and CMC with BC as amendments on cotton plants subjected to osmotic stress levels of 70 (70 OS) and 40 (40 OS). There were five treatment groups, namely: control (0% CMC-BC and 0% GA3-BC), 0.4%CMC-BC, 0.4%GA3-BC, 0.8%CMC-BC, and 0.8%GA3-BC. Each treatment was replicated five times with a completely randomized design (CRD). The results revealed that 0.8 GA3-BC led to increase in cotton shoot fresh weight (99.95%), shoot dry weight (95.70%), root fresh weight (73.13%), and root dry weight (95.74%) compared to the control group under osmotic stress. There was a significant enhancement in cotton chlorophyll a (23.77%), chlorophyll b (70.44%), and total chlorophyll (35.44%), the photosynthetic rate (90.77%), transpiration rate (174.44%), and internal CO2 concentration (57.99%) compared to the control group under the 40 OS stress. Thus 0.8GA3-BC can be potential amendment for reducing osmotic stress in cotton cultivation, enhancing agricultural resilience and productivity.

Seed priming is a physical method for increasing the stress tolerance of crops against stressful environmental conditions. Drought and high temperatures are important environmental factors that limit the growth and grain yield of wheat. The aim of our study is to determine the physiological (germination rate, root and shoot length, specific leaf area (SLA), relative water content (RWC), biomass, total chlorophyll amount (SPAD)), and biochemical (protein amount, hydrogen peroxide (H2O2) amount, catalase activity (CAT), ascorbate peroxidase activity (APX), glutathione reductase activity (GR)) changes that occur with thermo-priming in wheat seeds under drought stress (D) and heat stress (H). Our results showed that shoot lengths were drastically reduced with D, H, and HD compared to root lengths. Besides, combined stress protected RWC by 6.8% with 60 min thermo-priming compared to other stress treatments. Chlorophyll content decreased dramatically with D and H, while thermo-priming wasn’t limited to that decrease. In addition, SLA was decreased with all stress treatments, while it healed only with 60 min thermo-priming (HDT60) by 12%. H2O2 was increased with drought stress, while reduced with all heat stress treatments. Among them, HDT60 was found to be more effective than the others. GR activities were increased with thermo-priming by 14-18%, with D and H by 5%. Additionally, GR activity was increased with 30 min thermo-priming (HDT30) in HD treatment by 5.8%, while only with HD by 3.2%. Consequently, HDT60 seemed to effectively on biochemical parameters in wheat seedlings against drought and heat stresses.

Nostoc flagelliforme is a terrestrial cyanobacterium that can resist many types of stressors, including drought, ultraviolet radiation, and extreme temperatures. In this study, we identified the drought tolerance gene NfcrtO, which encodes a β-carotene ketolase, through screening the transcriptome of N. flagelliforme under water loss stress. Prokaryotic expression of NfcrtO under 0.6 mol/L sorbitol or under 0.3 mol/L NaCl stress significantly increased the growth rate of Escherichia coli. When NfcrtO was heterologously expressed in rice, the seedling height and root length of NfcrtO-overexpressing rice plants were significantly higher than those of the wild type (WT) plants grown on ½ Murashige and Skoog solid medium with 120 mmol/L mannitol at the seedling stage. Transcriptome analysis revealed that NfcrtO was involved in osmotic stress, antioxidant, and other stress-related pathways. Additionally, the survival rate of the NfcrtO-overexpression lines was significantly higher than that of the WT line under both hydroponic stress (24% PEG and 100 mmol/L H2O2) and soil drought treatment at the seedling stage. Physiological traits, including the activity levels of superoxide dismutase, peroxidase, catalase, total antioxidant capacity, and the contents of proline, trehalose, and soluble sugar, were significantly improved in the NfcrtO-overexpression lines relative to those in the WT line under 20% PEG treatment. Furthermore, when water was withheld at the booting stage, the grain yield per plant of NfcrtO-overexpression lines was significantly higher than that of the WT line. Yeast two-hybrid analysis identified interactions between NfcrtO and Dna J protein, E3 ubiquitin-protein ligase, and pyrophosphate-energized vacuolar membrane proton pump. Thus, heterologous expression of NfcrtO in rice could significantly improve the tolerance of rice to osmotic stress, potentially facilitating the development of new rice varieties.

Drought, a significant environmental challenge, presents a substantial risk to worldwide agriculture and the security of food supplies. In response, plants can perceive stimuli from their environment and activate defense pathways via various modulating networks to cope with stress. Drought tolerance, a multifaceted attribute, can be dissected into distinct contributing mechanisms and factors. Osmotic stress, dehydration stress, dysfunction of plasma and endosome membranes, loss of cellular turgidity, inhibition of metabolite synthesis, cellular energy depletion, impaired chloroplast function, and oxidative stress are among the most critical consequences of drought on plant cells. Understanding the intricate interplay of these physiological and molecular responses provides insights into the adaptive strategies plants employ to navigate through drought stress. Plant cells express various mechanisms to withstand and reverse the cellular effects of drought stress. These mechanisms include osmotic adjustment to preserve cellular turgor, synthesis of protective proteins like dehydrins, and triggering antioxidant systems to counterbalance oxidative stress. A better understanding of drought tolerance is crucial for devising specific methods to improve crop resilience and promote sustainable agricultural practices in environments with limited water resources. This review explores the physiological and molecular responses employed by plants to address the challenges of drought stress.

Despite substantial evidence suggesting that hydrogen gas (H2) can enhance osmotic tolerance in plants, the conventional supply method of hydrogen-rich water (HRW) poses challenges for large-scale agricultural applications. Recently, magnesium hydride (MgH2), a hydrogen storage material in industry, has been reported to yield beneficial effects in plants. This study aimed to investigate the effects and underlying mechanisms of MgH2 in plants under osmotic stress. Mung bean seedlings were cultured under control conditions or with 20% polyethylene glycol (PEG)-6000, with or without MgH2 addition (0.01 g L−1). Under our experimental conditions, the MgH2 solution maintained a higher H2 content and longer retention time than HRW. Importantly, PEG-stimulated endogenous H2 production was further triggered by MgH2 application. Further results revealed that MgH2 significantly alleviated the inhibition of seedling growth and reduced oxidative damage induced by osmotic stress. Pharmacological evidence suggests the MgH2-reestablished redox homeostasis was associated with activated antioxidant systems, particularly the ascorbate–glutathione cycle. The above observations were further supported by the enhanced activities and gene transcriptional levels of ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase. Overall, this study demonstrates the importance of MgH2 in mitigating osmotic stress in mung bean seedlings, providing novel insights into the potential agricultural applications of hydrogen storage materials.