Osmotic Stress Research Articles

Analysis of Stress Response Genes in Microtuberization of Potato Solanum tuberosum L.: Contributions to Osmotic and Combined Abiotic Stress Tolerance

Wild Solanum species have contributed many introgressed genes during domestication into current cultivated potatoes, enhancing their biotic and abiotic stress resistance and facilitating global expansion. Abiotic stress negatively impacts potato physiology and productivity. Understanding the molecular mechanisms regulating tuber development may help solve this global problem. We made a transcriptomic analysis of potato microtuberization under darkness, cytokinins, and osmotic stress conditions. A protein–protein interaction (PPI) network analysis identified 404 genes with high confidence. These genes were involved in important processes like oxidative stress, carbon metabolism, sterol biosynthesis, starch and sucrose metabolism, fatty acid biosynthesis, and nucleosome assembly. From this network, we selected nine ancestral genes along with eight additional stress-related genes. We used qPCR to analyze the expression of the selected genes under osmotic, heat–osmotic, cold–osmotic, salt–osmotic, and combined-stress conditions. The principal component analysis (PCA) revealed that 60.61% of the genes analyzed were associated with osmotic, cold–osmotic, and heat–osmotic stress. Seven out of ten introgression/domestication genes showed the highest variance in the analysis. The genes H3.2 and GAPCP1 were involved in osmotic, cold–osmotic, and heat–osmotic stress. Under combined-all stress, TPI and RPL4 were significant, while in salt–osmotic stress conditions, ENO1, HSP70-8, and PER were significant. This indicates the importance of ancestral genes for potato survival during evolution. The targeted manipulation of these genes could improve combined-stress tolerance in potatoes, providing a genetic basis for enhancing crop resilience.

The Characterization of R2R3-MYB Genes in Water Lily Nymphaea colorata Reveals the Involvement of NcMYB25 in Regulating Anthocyanin Synthesis

Nymphaea colorata, valued for its diverse flower colors and attractive shapes, is a popular ornamental aquatic plant. Anthocyanins provide color to flowers, and their biosynthesis is regulated by the R2R3-MYB transcription factor. In this study, we identified and analyzed the R2R3-MYB genes in N. colorata, focusing on their structure, evolution, expression patterns, regulatory mechanisms, and biological functions. We also investigated the role of the NcMYB25 gene in anthocyanin biosynthesis. There were 59 R2R3-MYB genes in N. colorata, distributed across 14 chromosomes. Among these, 14 genes were involved in segmental duplications and 6 in tandem duplications. Multiple R2R3-MYB transcription factors appeared to play a role in biological processes in N. colorata, including NcMYB48 in flavonoid synthesis, NcMYB33 in lignin synthesis, NcMYB23 in cold stress response, and NcMYB54 in osmotic stress response. Additionally, we identified 92 miRNAs in N. colorata, with 43 interacting with 35 R2R3-MYB genes. The NcMYB25 protein is localized in the nucleus and possesses transcriptional activation activity. Overexpression of the NcMYB25 gene in an apple pericarp resulted in anthocyanin accumulation. These findings provide insight into the evolutionary trajectory of the R2R3-MYB genes in N. colorata and highlight the regulatory function of the NcMYB25 gene in anthocyanin biosynthesis.

Physiological and transcriptomic analysis reveals the coating of microcapsules embedded with bacteria can enhance wheat salt tolerance

Salt stress is one of the most important abiotic stress factors limiting crop production. Therefore, improving the stress resistance of seeds is very important for crop growth. Our previous studies have shown that using microcapsules encapsulating bacteria (Pontibacter actiniarum DSM 19842) as seed coating for wheat can alleviate salt stress. In this study, the genes and pathways involved in the response of wheat to salt stress were researched further. The results showed that compared with the control, the coating can improve osmotic stress and decrease oxidative damage by increasing the content of proline (29.1%), the activity of superoxide dismutase (SOD) (94.2%), peroxidase (POD) (45.7%) and catalase (CAT) (3.3%), reducing the content of hydrogen peroxide (H2O2) (39.8%) and malondialdehyde (MDA) (45.9%). In addition, ribonucleic acid (RNA) sequencing data showed that 7628 differentially expressed genes (DEGs) were identified, and 4426 DEGs up-regulated, 3202 down-regulated in the coated treatment. Many DEGs related to antioxidant enzymes were up-regulated, indicating that coating can promote the expression of antioxidant enzyme-related genes and alleviate oxidative damage under salt stress. The differential gene expression analysis demonstrated up-regulation of 27 genes and down-regulation of 20 genes. Transcription factor families, mostly belonging to bHLH, MYB, B3, NAC, and WRKY. Overall, this seed coating can promote the development of sustainable agriculture in saline soil.

GA-sensitive Rht13 gene improves root architecture and osmotic stress tolerance in bread wheat

The root architecture, more seminal roots, and Deeper roots help the plants to uptake the resources from the deeper soil layer to ensure better growth. The Gibberellic acid-sensitive (GA-sensitive) Rht genes are well known for increasing drought tolerance in wheat. Much work has been performed on the effect of these genes on the plant agronomic traits and little work has been done on the effect of Rht genes on seminal roots and root architecture. This study was designed to evaluate 200 wheat genotypes under normal and osmotic stress. The genotypes were sown in the solution culture and laid under CRD factorial arrangement with three replications and two factors i.e., genotypes and treatments viz. normal and osmotic stress (20% PEG-6000) applied one week after germination. The data was recorded for the root traits. Results demonstrated that out of 200 genotypes, the GA-sensitive Rht13 gene was amplified in 21 genotypes with a fragment length of 1089 bp. In comparison, the GA-insensitive Rht1 gene was amplified in 24 genotypes with a band size of 228 bp. From 200 wheat genotypes, 122 genotypes produced 5 seminal roots, 4 genotypes 4 seminal roots, and 74 genotypes 3 seminal roots. The genotypes G-3 (EBW11TALL#1/WESTONIA-Rht5//QUAIU#1), G-6 (EBW01TALL#1/SILVERSTAR-Rht13B//ROLF07) and G-8 (EBW01TALL#1/SILVERSTAR-Rht13B//NAVJ07) produced 5 seminal roots and have longer coleoptile (> 4.0 cm), root (> 11.0 cm) and shoot (> 17 cm) under normal and osmotic stress. Furthermore, Ujala 16, Galaxy-13, and Fareed-06 produced 3 seminal roots and have short coleoptile (< 3 cm), root (< 9.0 cm) and shoot (< 10.0 cm). These results showed that the genotypes showing the presence of GA-sensitive Rht genes produced a greater number of seminal roots, increased root/shoot growth, and osmotic stress tolerance compared to the genotypes having GA-insensitive Rht genes. Thus, the Rht13 gene improved the root architecture which will help to uptake the nutrients from deeper soil layers. Utilization of Rht13 in wheat breeding has the potential to improve osmotic stress tolerance in wheat.

Origin and evolution of the blue light receptor cryptochromes (CRY1/2) in aquatic angiosperms.

Cryptochromes (CRYs), which are responsible for sensing blue light in plants, play a critical role in regulating blue light signals and circadian rhythms. However, their functions extend beyond light detection, as they also aid plants in adapting to stress and potentially other regulatory mechanisms. Aquatic angiosperms, which independently evolved from various angiosperm lineages, have developed specific adaptations to unique light qualities and environmental stressors found in aquatic habitats compared to terrestrial ones. It was hypothesized that the sequences and regulatory networks of angiosperm CRY1/2 underwent adaptive evolution in different aquatic angiosperm lineages. To test this hypothesis, we compiled comprehensive datasets consisting of 55 green plant genomes (including 37 angiosperm genomes), 80 angiosperm transcriptomes, and 4 angiosperm expression networks. Through comparative analysis, we found that CRY1 originated from a common ancestor of seed plants, whereas CRY2 originated from a common ancestor of land plants. In angiosperms, the CRY1/2 sequences of aquatic lineages exhibited positive selection, and the conserved valine-proline (VP) motif of CRY2 showed a convergent loss in two aquatic species. Co-expressed genes associated with blue light receptors (CRY) showed adaptations to aquatic environments, specifically in relation to flooding and osmotic stress. These discoveries shed light on the adaptive evolution of CRY1/2, encompassing their origins, sequences, and regulatory networks. Furthermore, these results provide valuable insights for investigating the uncharacterized functions and regulatory pathways of CRY and offer potential targets for enhancing growth and adaptation in agricultural plants.

Drought Tolerance in Plants: Physiological and Molecular Responses

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.

Convergent reductive evolution in bee-associated lactic acid bacteria.

Distantly related organisms may evolve similar traits when exposed to similar environments or engaging in certain lifestyles. Several members of the Lactobacillaceae [lactic acid bacteria (LAB)] family are frequently isolated from the floral niche, mostly from bees and flowers. In some floral LAB species (henceforth referred to as bee-associated LAB), distinctive genomic (e.g., genome reduction) and phenotypic (e.g., preference for fructose over glucose or fructophily) features were recently documented. These features are found across distantly related species, raising the hypothesis that specific genomic and phenotypic traits evolved convergently during adaptation to the floral environment. To test this hypothesis, we examined representative genomes of 369 species of bee-associated and non-bee-associated LAB. Phylogenomic analysis unveiled seven independent ecological shifts toward the bee environment in LAB. In these species, we observed significant reductions of genome size, gene repertoire, and GC content. Using machine leaning, we could distinguish bee-associated from non-bee-associated species with 94% accuracy, based on the absence of genes involved in metabolism, osmotic stress, or DNA repair. Moreover, we found that the most important genes for the machine learning classifier were seemingly lost, independently, in multiple bee-associated lineages. One of these genes, acetaldehyde-alcohol dehydrogenase (adhE), encodes a bifunctional aldehyde-alcohol dehydrogenase which has been associated with the evolution of fructophily, a rare phenotypic trait that is pervasive across bee-associated LAB species. These results suggest that the independent evolution of distinctive phenotypes in bee-associated LAB has been largely driven by independent losses of the same sets of genes.IMPORTANCESeveral LAB species are intimately associated with bees and exhibit unique biochemical properties with potential for food applications and honeybee health. Using a machine learning-based approach, our study shows that adaptation of LAB to the bee environment was accompanied by a distinctive genomic trajectory deeply shaped by gene loss. Several of these gene losses occurred independently in distantly related species and are linked to some of their unique biotechnologically relevant traits, such as the preference for fructose over glucose (fructophily). This study underscores the potential of machine learning in identifying fingerprints of adaptation and detecting instances of convergent evolution. Furthermore, it sheds light onto the genomic and phenotypic particularities of bee-associated bacteria, thereby deepening the understanding of their positive impact on honeybee health.

Time-course analysis of the transcriptome of Arabidopsis thaliana leaves under high-concentration ammonium sulfate treatment

ABSTRACT Ammonium fertilization is of great interest for future agriculture, as unlike nitrate, ammonium use efficiency does not decrease in C3 plants, even in environments with elevated CO2 concentrations. However, excess ammonium often results in toxic effects such as growth suppression and chlorosis, i.e. ammonium toxicity. The addition of nitrate, a major source of nitrogen commonly found in soils, has been shown to alleviate these toxic effects. Understanding the mechanisms of ammonium toxicity in the presence of nitrate is crucial for the effective use of ammonium fertilizers in crop cultivation. To elucidate these responses, a time-course analysis of the transcriptome was performed on A. thaliana leaves treated with high concentrations of ammonium sulfate in the presence of sufficient nitrate. The expression of nitrate-inducible genes tended to be downregulated by the treatment. The expression of genes relating to abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), and membrane trafficking was upregulated, whereas that of photosynthesis-, auxin-, and cytokinin-related genes involved in growth and development was downregulated. The induction of many osmotic stress-responsive genes and nitric oxide (NO)-inducible genes suggests the involvement of osmotic stress and NO signaling in the response. This study provides a novel and comprehensive overview of transcriptional changes occurring in response to high ammonium sulfate concentrations with sufficient nitrate, and sheds light on potential pathways involved in ammonium toxicity under these conditions.

Ecological success of extreme halophiles subjected to recurrent osmotic disturbances is primarily driven by congeneric species replacement.

To understand how extreme halophiles respond to recurrent disturbances, we challenged the communities thriving in salt-saturated (~36% salts) ~230L brine mesocosms to repeated dilutions down to 13% (D13 mesocosm) or 20% (D20 mesocosm) salts each time mesocosms reached salt saturation due to evaporation (for 10 and 17cycles, respectively) over 813days. Depending on the magnitude of dilution, the most prevalent species, Haloquadratum walsbyi and Salinibacter ruber, either increased in dominance by replacing less competitive populations (for D20, moderate stress conditions), or severely decreased in abundance and were eventually replaced by other congeneric species better adapted to the higher osmotic stress (for D13, strong stress conditions). Congeneric species replacement was commonly observed within additional abundant genera in response to changes in environmental or biological conditions (e.g. phage predation) within the same system and under a controlled perturbation of a relevant environmental parameter. Therefore, a genus is an ecologically important level of diversity organization, not just a taxonomic rank, that persists in the environment based on congeneric species replacement due to relatively high functional overlap (gene sharing), with important consequences for the success of the lineage, and similar to the success of a species via strain-replacement. Further, our results showed that successful species were typically accompanied by the emergence of their own viral cohorts, whose intra-cohort diversity appeared to strongly covary with, and likely drive, the intra-host diversity. Collectively, our results show that brine communities are ecologically resilient and continuously adapting to changing environments by transitioning to alternative stable states.

Gene Expression Analysis for Drought Tolerance in Early Stage of Potato Plant Development

Drought has increasingly affected the yield of Solanum tuberosum L. (potato) every year over the last decade, posing serious economic problems for the global agricultural industry. Therefore, it is important to research drought tolerance in plants and obtain more robust varieties of crops. The aim of the present work was to study the expression of drought-upregulated genes in drought-tolerant and drought-sensitive varieties of potato. Bioreactors were used to identify whether each variety was drought-tolerant or drought-sensitive; then, expression analysis was performed according to the morphological characteristics of the plantlets in two different media: Murashige and Skoog (MS) medium and MS medium with 20% PEG-6000 to simulate osmotic stress. Based on the quantitative parameters of six initial varieties, two varieties were selected (Gala and Aksor) for further gene expression analysis. The expression of genes commonly upregulated in drought (ER24, TAS14, DREB147315, PP2C, 102605413 and NF-YC4) was higher in the drought-tolerant variety than in the sensitive one. Therefore, the expression of these genes can be used to determine the drought tolerance of a potato variety in vitro in the early plant development stage. Moreover, comparative analysis showed that some of the targeted genes used to identify drought tolerance in this study are conserved across different plant species.

Cryopreservation, cryoprotectants, and potential risk of epigenetic alteration.

The cryopreservation of gametes and embryos has increased notably over the past 20years and is now an essential part of assisted reproductive technologies (ARTs). However, because the cryopreservationprocess is un-physiological for human cells, gametes, and embryos, cryobiologists have suggested diverse methods to successfully cryopreserve human gametes and embryos in order to maintain their viability and assure successful pregnancy. During the first period of early development, major waves of epigenetic reprogramming-crucial for the fate of the embryo-occur. Recently, concerns relating to the increased incidence of epigenetic anomalies and genomic-imprinting disorders have been reported after ARTs and cryopreservation. Epigenetic reprogramming is particularly susceptible to environmental and un-physiological conditions such as ovarian stimulation, embryo culture, and cryopreservation that might collectively affect epigenetics dysregulation. Additionally, recent literature suggests that epigenetic and transcriptomic profiles are sensitive to the stress induced by vitrification, osmotic shock, oxidative stress, rapid temperature and pH changes, and cryoprotectants; it is therefore critical to have a more comprehensive understanding of the potential induced perturbations of epigenetic modifications that may be associated with vitrification. The aim of this paper is to present a critical evaluation of the association of gamete and embryo cryopreservation, use of cryoprotectants, and epigenetic dysregulations with potential long-term consequences for offspring health.

Osmotic signaling releases PP2C-mediated inhibition of Arabidopsis SnRK2s via the receptor-like cytoplasmic kinase BIK1.

Osmotic stress and abscisic acid (ABA) signaling are important for plant growth and abiotic stress resistance. Activation of osmotic and ABA signaling downstream of the PYL-type ABA receptors requires the release of SnRK2 protein kinases from the inhibition imposed by PP2Cs. PP2Cs are core negative regulators that constantly interact with and inhibit SnRK2s, but how osmotic signaling breaks the PP2C inhibition of SnRK2s remains unclear. Here, we report that an Arabidopsis receptor-like cytoplasmic kinase, BIK1, releases PP2C-mediated inhibition of SnRK2.6 via phosphorylation regulation. The dominant abi1-1 ABA-signaling mutation (G180D) disrupts PYL-PP2C interactions and disables PYL-initiated release of SnRK2s; in contrast, BIK1 releases abi1-1-mediated inhibition of SnRK2.6. BIK1 interacts with and phosphorylates SnRK2.6 at two tyrosine residues, which are critical for SnRK2.6 activation and function. Phosphorylation of the two tyrosine residues may affect the docking of the tryptophan "lock" of PP2C into SnRK2.6. Moreover, the bik1 mutant is defective in SnRK2 activation, stress-responsive gene expression, ABA accumulation, growth maintenance, and water loss under osmotic stress. Our findings uncover the critical role of BIK1 in releasing PP2C-mediated inhibition of SnRK2s under osmotic stress.

The biology of water homeostasis.

Water homeostasis is controlled by a brain-kidney axis that consists of central osmoreceptors, synthesis and secretion of arginine vasopressin (AVP) and AVP-responsive aquaporin-2 (AQP2) water channels in kidney collecting duct principal cells that facilitate water reabsorption. In addition to AVP, thirst represents a second line of defense to maintain water balance. Water balance disorders arise because of deficiency, resistance or inappropriate secretion of AVP or disturbances in thirst sensation (hypodipsia, polydipsia). People with water balance disorders are prone to develop hyponatremia or hypernatremia, which expose cells to osmotic stress and activate cell volume regulation mechanisms. This review covers several recent insights that have expanded our understanding of central osmoregulation, AQP2 regulation and cell volume regulation. This includes the role of with-no-lysine kinase 1 (WNK1) as a putative central osmolality sensor and, more generally, as an intracellular crowding sensor that coordinates the cell volume rescue response by activating sodium and potassium cotransporters. Furthermore, several new regulators of AQP2 have been identified, including for AVP-dependent AQP2 regulation (yes-associated protein, nuclear factor of activated T-cells, microRNAs) and AVP-independent AQP2 regulation (epidermal growth factor receptor, fluconazole, prostaglandin E2). It is also becoming increasingly clear that long-term cell volume adaptation to chronic hypotonicity through release of organic osmolytes comes at the expense of compromised organ function. This potentially explains the complications of chronic hyponatremia, including cognitive impairment, bone loss and vascular calcification. This review will illustrate why these new insights derived from basic science are also relevant for developing new approaches to treat water balance disorders.

Co-cultivation of selected Lactiplantibacillus plantarum strains with starter cultures under osmotic stress increases folate content and enhances product quality in fermented dairy

This study aimed to identify lactic acid bacteria (LAB) strains with high folate production potential to enhance the folate content in fermented dairy products. From 284 LAB strains sourced from fermented vegetables and dairy, six were selected for their outstanding folate production. Among these, Lactiplantibacillus plantarum TXZ2-26 and L. plantarum FJ2-3 demonstrated strong synergistic interactions with the starter culture, resulting in an increased total LAB cell count after co-cultivation. The effects of five different stress conditions on the growth, folate production, and expression of key folate-synthesis genes (folE, folP, folQ, folB, folK) in the two strains were further examined, revealing that the two strains demonstrated increased folate production under 3% NaCl stress. Finally, both unstressed and NaCl-stressed strains were used in the fermentation of goat and cow milk alongside the starter culture. The results revealed that the addition of L. plantarum TXZ2-26 and FJ2-3 significantly boosted the folate content of the fermented dairy products and improved their physicochemical properties, with the stressed strains exhibiting a more pronounced effect. These findings underscore the potential of L. plantarum TXZ2-26 and FJ2-3 as effective probiotics for producing folate-enriched fermented foods.

Activity of photosynthetic pigments and the antioxidant system in sunflower under drought stress

Background. The study is of particular importance in view of the increasing pace of global climate aridization. The article highlights the results of an experiment on the effect of drought on the physiological status of seedlings of cv. ‘Poseidon 625’ representing an important food crop – sunflower (Helianthus annuus L.). Materials and methods. The experiment included a group of control samples grown with sufficient moisture and four impact groups subjected to osmotic stress. The intensity of accumulation of lipid peroxidation products (LPP) was measured by the reaction of malondialdehyde (MDA) with thiobarbeturic acid; catalase activity was assessed by a photocolorimetric method based on the interaction between hydrogen peroxide and potassium iodide; the content of pigments (Chl a, Chl b, Сar) was calculated spectrophotometrically in acetone extract. Results. The degree of POL accumulation in the impact groups of the experiment was found to be many times higher than the values in the control samples, which was confirmed by a rapid increase in the MDA concentration in response to a growing water shortage. The accumulation of oxygen free radicals triggered the mechanisms of antioxidant protection of seedlings by synthesizing catalase, the concentration of which increased proportionally to the accumulation of POL. At the same time, the rapid accumulation of POL in the absence of irrigation and under osmotic stress of 3 and 5 atm led to a suppression of low-molecular-weight components of protection (carotenoids) and activation of their synthesis only when critical values of osmotic stress were reached. Conclusion. As a result of the experiment, catalase was identified as the main component of antioxidant protection in sunflower seedlings. Due to the activation of its synthesis, the concentrations of Chl a and Chl b decreased, attesting to the activation of the mechanisms protecting the photosynthetic activity in seedlings, and their antioxidant status.

Beyond hemoglobin: Critical role of 2,3-bisphosphoglycerate mutase in kidney function and injury.

2,3-bisphosphoglycerate mutase (BPGM) is traditionally recognized for its role in modulating oxygen affinity to hemoglobin in erythrocytes. Recent transcriptomic analyses, however, have indicated a significant upregulation of BPGM in acutely injured murine and human kidneys, suggesting a potential renal function for this enzyme. Here we aim to explore the physiological role of BPGM in the kidney. A tubular-specific, doxycycline-inducible Bpgm-knockout mouse model was generated. Histological, immunofluorescence, and proteomic analyses were conducted to examine the localization of BPGM expression and the impact of its knockout on kidney structure and function. Invitro studies were performed to investigate the metabolic consequences of Bpgm knockdown under osmotic stress. BPGM expression was localized to the distal nephron and was absent in proximal tubules. Inducible knockout of Bpgm resulted in rapid kidney injury within 4 days, characterized by proximal tubular damage and tubulointerstitial fibrosis. Proteomic analyses revealed involvement of BPGM in key metabolic pathways, including glycolysis, oxidative stress response, and inflammation. Invitro, Bpgm knockdown led to enhanced glycolysis, decreased reactive oxygen species elimination capacity under osmotic stress, and increased apoptosis. Furthermore, interactions between nephron segments and immune cells in the kidney suggested a mechanism for propagating stress signals from distal to proximal tubules. BPGM fulfills critical functions beyond the erythrocyte in maintaining glucose metabolism in the distal nephron. Its absence leads to metabolic imbalances, increased oxidative stress, inflammation, and ultimately kidney injury.

Essential role of proline synthesis and the one-carbon metabolism pathways for systemic virulence of Streptococcus pneumoniae.

Virulence screens have indicated potential roles during Streptococcus pneumoniae infection for the one-carbon metabolism pathway component Fhs and proline synthesis mediated by ProABC. To define how these metabolic pathways affect S. pneumoniae virulence, we have investigated the phenotypes, transcription, and metabolic profiles of Δfhs and ΔproABC mutants. S. pneumoniae capsular serotype 6B BHN418 Δfhs and ΔproABC mutant strains had strongly reduced virulence in mouse sepsis and pneumonia models but could colonize the nasopharynx. Both mutant strains grew normally in complete media but had markedly impaired growth in chemically defined medium, human serum, and human cerebrospinal fluid. The BHN418 ΔproABC strain also had impaired growth under conditions of osmotic and oxidative stress. The virulence role of proABC was strain specific, as the D39 ΔproABC strain could still cause septicemia and grow in serum. Compared to culture in broth, in serum, the BHN418 Δfhs and ΔproABC strains showed considerable derangement in global gene transcription that affected multiple but different metabolic pathways for each mutant strain. Metabolic data suggested that Δfhs had an impaired stringent response, and when cultured in sera, BHN418 Δfhs and ΔproABC were under increased oxidative stress and had altered lipid profiles. Loss of proABC also affected carbohydrate metabolism and the accumulation of peptidoglycan synthesis precursors in the BHN418 but not the D39 background, linking this phenotype to the conditional virulence phenotype. These data identify the S. pneumoniae metabolic functions affected by S. pneumoniae one-carbon metabolism and proline biosynthesis, and the role of these genetic loci for establishing systemic infection.IMPORTANCERapid adaptation to grow within the physiological conditions found in the host environment is an essential but poorly understood virulence requirement for systemic pathogens such as Streptococcus pneumoniae. We have now demonstrated an essential role for the one-carbon metabolism pathway and a conditional role depending on strain background for proline biosynthesis for S. pneumoniae growth in serum or cerebrospinal fluid, and therefore for systemic virulence. RNAseq and metabolomic data demonstrated that the loss of one-carbon metabolism or proline biosynthesis has profound but differing effects on S. pneumoniae metabolism in human serum, identifying the metabolic processes dependent on each pathway during systemic infection. These data provide a more detailed understanding of the adaptations required by systemic bacterial pathogens in order to cause infection and demonstrate that the requirement for some of these adaptations varies between strains from the same species and could therefore underpin strain variations in virulence potential.

Salinity influence on Mytilus galloprovincialis exposed to antineoplastic agents: a transcriptomic, biochemical, and histopathological approach

Nowadays, aquatic species face a variety of environmental risks associated with pharmaceutical consumption. More specifically, the increased number of cancer patients has been accompanied by an increased consumption of antineoplastic drugs, such as ifosfamide (IF) and cyclophosphamide (CP). These drugs have been found in aquatic ecosystems, raising concerns about their impact, especially on estuarine species, as marine waters are the final recipients of continental effluents. Simultaneously, predicted climatic changes, such as salinity shifts, may threaten organisms. Considering this, the present research aims to investigate the combined effects of IF and CP, and salinity shifts. For this, a transcriptomic, biochemical, and histopathological assessment was made using the bivalve species Mytilus galloprovincialis exposed for 28 days to IF and CP (500 ng/L), individually, at different salinity levels (20, 30, and 40). IF and CP up-regulated metabolism-related gene cyp3a1, with CP also affecting abcc gene, showing minimal salinity impact and highlighting the importance of these metabolic routes in mussels. Salinity shifts affected the transcription of genes related to apoptosis and cell cycle growth, such as p53, as well as the aerobic metabolism, the antioxidant and biotransformation mechanisms. These findings indicate mussels' high metabolic adaptability to osmotic stress. Under CP exposure and low salinity, mussels exhibited increased cellular damage and histopathological effects in digestive gland tubules, revealing detrimental effects towards M. galloprovincialis, and suggesting that a metabolic slowdown and activation of antioxidant mechanisms helped prevent oxidative damage at the control and high salinities. Overall, results reinforce the need for antineoplastics ecotoxicological risk assessment, especially under foreseen climate change scenarios.

Seed Germination Responses to Temperature and Osmotic Stress Conditions in Brachiaria Forage Grasses

Seed Germination Responses to Temperature and Osmotic Stress Conditions in Brachiaria Forage Grasses

Natural SNP Variation in GbOSM1 Promotor Enhances Verticillium Wilt Resistance in Cotton.

Osmotin is classified as the pathogenesis-related protein 5 group. However, its molecular mechanism involved in plant disease resistance remains largely unknown. Here, a Verticillium wilt (VW) resistance-related osmotin gene is identified in Gossypium barbadense (Gb), GbOSM1. GbOSM1 is preferentially expressed in the roots of disease-resistant G. barbadense acc. Hai7124 and highly induced by Verticillium dahliae (Vd). Silencing GbOSM1 reduces the VW resistance of Hai7124, while overexpression of GbOSM1 in disease-susceptible G. hirsutum improves tolerance. GbOSM1 predominantly localizes in tonoplasts, while it relocates to the apoplast upon exposure to osmotic stress or Vd infection. GbOSM1 confers VW resistance by hydrolyzing cell wall polysaccharides of Vd and activating plant immune pathways. Natural variation contributes to a differential CCAAT/CCGAT elements in the OSM1 promoter in cotton accessions. All G. hirsutum (Gh) exhibit the CCAAT haplotype, while there are two haplotypes of CCAAT/CCGAT in G. barbadense, with higher expression and stronger VW resistance in CCGAT haplotype. A NFYA5 transcription factor binds to the CCAAT element of GhOSM1 promoter and inhibits its transcription. Silencing GhNFYA5 results in higher GhOSM1 expression and enhances VW resistance. These results broaden the insights into the functional mechanisms of osmotin and provide an effective strategy to breed VW-resistant cotton.