Osmotic Stress Resistance Research Articles

Enhanced catabolism of glycine betaine and derivatives provides improved osmotic stress protection in Methylorubrum extorquens PA1.

Integration of metabolites into the overall metabolic network of a cell requires careful coordination dependent upon the ultimate usage of the metabolite. Different stoichiometric needs, and thus pathway fluxes, must exist for compounds destined for diverse uses, such as carbon sources, nitrogen sources, or stress-protective agents. Herein, we expand upon our previous work that highlighted the nature of glycine betaine (GB) metabolism in Methylobacteria to examine the utilization of GB-derivative compounds dimethylglycine (DMG) and sarcosine into Methylorubrum extorquens in different metabolic capacities, including as sole nitrogen and/or carbon sources. We isolated gain-of-function mutations that allowed M. extorquens PA1 to utilize dimethylglycine as a carbon source and dimethylglycine and sarcosine as nitrogen source. Characterization of mutants demonstrated selection for variants of the AraC-like regulator Mext_3735 that confer constitutive expression of the GB metabolic gene cluster, allowing direct utilization of the downstream GB derivatives. Finally, among the distinct isolates examined, we found that catabolism of the osmoprotectant used for selection (GB or dimethylglycine) enhanced osmotic stress resistance provided in the presence of that particular osmolyte. Thus, access to the carbon and nitrogen and osmoprotective effects of GB and DMG are made readily accessible through adaptive mutations. In M. extorquens PA1, the limitations to exploiting this group of compounds appear to exist predominantly at the levels of gene regulation and functional activity, rather than being constrained by transport or toxicity.IMPORTANCEOsmotic stress is a common challenge for bacteria colonizing the phyllosphere, where glycine betaine (GB) can be found as a prevalent osmoprotectant. Though Methylorubrum extorquens PA1 cannot use GB or its demethylation products, dimethylglycine (DMG) and sarcosine, as a sole carbon source, utilization is highly selectable via single nucleotide changes for both GB and DMG growth. The innate inability to use these compounds is due to limited flux through steps in the pathway and regulatory constraints. Herein, the characterization of the transcriptional regulator, Mext_3735 (GbdR), expands our understanding of the various roles in which GB derivatives can be used in M. extorquens PA1. Interestingly, increased catabolism of GB and derivatives does not interfere with, but rather improves, the ability of cells to thrive under increased salt stress conditions, suggesting that metabolic flux improves stress tolerance rather than providing a distinct tension between uses.

Genome-wide characterization of Remorin gene family and their responsive expression to abiotic stresses and plant hormone in Brassica napus.

Remorin proteins could be positively related to salt and osmotic stress resistance in rapeseed. Remorins (REMs) play a crucial role in adaptations to adverse environments. However, their roles in abiotic stress and phytohormone responses in oil crops are still largely unknown. In this study, we identified 47 BnaREM genes in the B.napus genome. Phylogenetic relationship and synteny analysis revealed that they were categorized into 5 distinct groups and have gone through 55 segmental duplication events under purifying selection. Gene structure and conserved domains analysis demonstrated that they were highly conserved and all BnaREMs contained a conserved Remorin_C domain, with a variable N-terminal region. Promoter sequence analysis showed that BnaREM gene promoters contained various hormones and stress-related cis-acting elements. Transcriptome data from BrassicaEDB database exhibited that all BnaREMs were ubiquitously expressed in buds, stamens, inflorescences, young leaves, mature leaves, roots, stems, seeds, silique pericarps, embryos and seed coats. The qRT-PCR analysis indicated that most of them were responsive to ABA, salt and osmotic treatments. Further mutant complementary experiments revealed that the expression of BnaREM1.3-4C-1 in the Arabidopsis rem1.3 mutant restored the retarded growth phenotype and the ability to resistance to salt and osmotic stresses. Our findings provide fundamental information on the structure and evolutionary relationship of the BnaREM family genes in rapeseed, and reveal the potential function of BnaREM1.3-4C-1 in stress and hormone response.

Exogenous application of 5-NGS increased osmotic stress resistance by improving leaf photosynthetic physiology and antioxidant capacity in maize.

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. 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. 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. 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.

Differentially Expressed Genes Identification of Kohlrabi Seedlings (Brassica oleracea var. caulorapa L.) under Polyethylene Glycol Osmotic Stress and AP2/ERF Transcription Factor Family Analysis.

Osmotic stress is a condition in which plants do not get enough water due to changes in environmental factors. Plant response to osmotic stress is a complex process involving the interaction of different stress-sensitive mechanisms. Differentially expressed genes and response mechanisms of kohlrabi have not been reported under osmotic stress. A total of 196,642 unigenes and 33,040 differentially expressed unigenes were identified in kohlrabi seedlings under polyethylene glycol osmotic stress. AP2/ERF, NAC and eight other transcription factor family members with a high degree of interaction with CAT and SOD antioxidant enzyme activity were identified. Subsequently, 151 AP2/ERF genes were identified and analyzed. Twelve conserved motifs were searched and all AP2/ERF genes were clustered into four groups. A total of 149 AP2/ERF genes were randomly distributed on the chromosome, and relative expression level analysis showed that BocAP2/ERF genes of kohlrabi have obvious specificity in different tissues. This study lays a foundation for explaining the osmotic stress resistance mechanism of kohlrabi and provides a theoretical basis for the functional analysis of BocAP2/ERF transcription factor family members.

Function analysis of transcription factor OSR1 regulating osmotic stress resistance in maize

BackgroundMaize is a major cereal crop world widely, however, the yield of maize is frequently limited by dehydration and even death of plants, which resulted from osmotic stress such as drought and salinity. Dissection of molecular mechanisms controlling stress tolerance will enable plant scientists and breeders to increase crops yield by manipulating key regulatory components. MethodsThe candidate OSR1 gene was identified by map-based cloning. The expression level of OSR1 was verified by qRT-PCR and digital PCR in WT and osr1 mutant. Electrophoretic mobility shift assay, transactivation activity assay, subcellular localization, transcriptome analysis and physiological characters measurements were conducted to analyze the function of OSR1 in osmotic stress resistance in maize. ResultsThe osr1 mutant was significantly less sensitive to osmotic stress than the WT plants and displayed stronger water-holding capacity, and the OSR1 homologous mutant in Arabidopsis showed a phenotype similar with maize osr1 mutant. Differentially expressed genes (DEGs) were identified between WT and osr1 under osmotic stress by transcriptome analysis, the expression levels of many genes, such as LEA, auxin-related factors, PPR family members, and TPR family members, changed notably, which may primarily involve in osmotic stress or promote root development. ConclusionsOSR1 may serve as a negative regulatory factor in response to osmotic stress in maize. The present study sheds new light on the molecular mechanisms of osmotic stress in maize.

Physiological and Transcriptomic Analyses Reveal the Mechanisms Underlying Methyl Jasmonate-Induced Mannitol Stress Resistance in Banana.

Exogenous methyl jasmonate (MeJA) application has shown promising effects on plant defense under diverse abiotic stresses. However, the mechanisms underlying MeJA-induced stress resistance in bananas are unclear. Therefore, in this study, we treated banana plants with 100 μM MeJA before inducing osmotic stress using mannitol. Plant phenotype and antioxidant enzyme activity results demonstrated that MeJA improved osmotic stress resistance in banana plants. Thereafter, to explore the molecular mechanisms underlying MeJA-induced osmotic stress resistance in banana seedlings, we conducted high-throughput RNA sequencing (RNA-seq) using leaf and root samples of "Brazilian" banana seedlings treated with MeJA for 0 h and 8 h. RNA-seq analysis showed that MeJA treatment upregulated 1506 (leaf) and 3341 (root) genes and downregulated 1768 (leaf) and 4625 (root) genes. Then, we performed gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses on the differentially expressed genes. We noted that linoleic acid metabolism was enriched in both root and leaf samples, and the genes of this pathway exhibited different expression patterns; 9S-LOX genes were highly induced by MeJA in the leaves, whereas 13S-LOX genes were highly induced in the roots. We also identified the promoters of these genes, as the differences in response elements may contribute to tissue-specific gene expression in response to MeJA application in banana seedlings. Overall, the findings of this study provide insights into the mechanisms underlying abiotic stress resistance in banana that may aid in the improvement of banana varieties relying on molecular breeding.

Genome-Wide Analysis of Family-1 UDP-Glycosyltransferases in Potato (Solanum tuberosum L.): Identification, Phylogenetic Analysis and Determination of Response to Osmotic Stress.

Family-1 UDP-glycosyltransferases (UGTs) are the most common and functional glycosyltransferases in the plant world. UGT is closely related to plant growth and the response to abiotic stress. However, despite systematic research, our understanding of potato UGT genes is still unclear. In this study, we identified 174 potato UGT proteins based on their conserved plant secondary product glycosyltransferase (PSPG) motifs. Phylogenetic analyses were used to compare these proteins with Arabidopsis UGTs and other plant UGTs, and it was found that they could be clustered into 18 distinct groups. Patterns of intron gain/loss and intron phases within potato UGTs revealed highly conserved intron insertion events. The promoter cis-elements of these 174 UGT genes were systematically investigated. The promoter regions of these UGT genes are known to contain various classes of cis-acting compounds. These include elements that are light-responsive, phytohormone-responsive, and stress-responsive. Transcriptome data analysis established that 25, 10, 6, and 4 of these 174 UGT genes were specifically expressed in leaves, roots, stolons, and young tubers, respectively. The mannitol-treated transcriptomic data showed thirty-eight UGT genes were significantly upregulated. The quantitative real-time PCR results showed that the four genes were all responsive to osmotic stress under a 10% PEG6000 treatment. The results of our study provide a basis for clarifying the molecular mechanism of potato osmotic stress resistance and better understanding its function in the future.

Overexpression of Lolium multiflorum LmMYB1 Enhances Drought Tolerance in Transgenic Arabidopsis.

Lolium multiflorum is one of the world-famous forage grasses with rich biomass, fast growth rate and good nutritional quality. However, its growth and forage yield are often affected by drought, which is a major natural disaster all over the world. MYB transcription factors have some specific roles in response to drought stress, such as regulation of stomatal development and density, control of cell wall and root development. However, the biological function of MYB in L. multiflorum remains unclear. Previously, we elucidated the role of LmMYB1 in enhancing osmotic stress resistance in Saccharomyces cerevisiae. Here, this study elucidates the biological function of LmMYB1 in enhancing plant drought tolerance through an ABA-dependent pathway involving the regulation of cell wall development and stomatal density. After drought stress and ABA stress, the expression of LmMYB1 in L. multiflorum was significantly increased. Overexpression of LmMYB1 increased the survival rate of Arabidopsis thaliana under drought stress. Under drought conditions, expression levels of drought-responsive genes such as AtRD22, AtRAB and AtAREB were up-regulated in OE compared with those in WT. Further observation showed that the stomatal density of OE was reduced, which was associated with the up-regulated expression of cell wall-related pathway genes in the RNA-Seq results. In conclusion, this study confirmed the biological function of LmMYB1 in improving drought tolerance by mediating cell wall development through the ABA-dependent pathway and thereby affecting stomatal density.

Identification and Characterization of a New Regulator, TagR, for Environmental Stress Resistance Based on the DNA Methylome of Streptomyces roseosporus.

DNA methylation is a defense that microorganisms use against extreme environmental stress, and improving resistance against environmental stress is essential for industrial actinomycetes. However, research on strain optimization utilizing DNA methylation for breakthroughs is rare. Based on DNA methylome analysis and KEGG pathway assignment in Streptomyces roseosporus, we discovered an environmental stress resistance regulator, TagR. A series of in vivo and in vitro experiments identified TagR as a negative regulator, and it is the first reported regulator of the wall teichoic acid (WTA) ABC transport system. Further study showed that TagR had a positive self-regulatory loop and m4C methylation in the promoter improved its expression. The ΔtagR mutant exhibited better hyperosmotic resistance and higher decanoic acid tolerance than the wild type, which led to a 100% increase in the yield of daptomycin. Moreover, enhancing the expression of the WTA transporter resulted in better osmotic stress resistance in Streptomyces lividans TK24, indicating the potential for wide application of the TagR-WTA transporter regulatory pathway. This research confirmed the feasibility and effectiveness of mining regulators of environmental stress resistance based on the DNA methylome, characterized the mechanism of TagR, and improved the resistance and daptomycin yield of strains. Furthermore, this research provides a new perspective on the optimization of industrial actinomycetes. IMPORTANCE This study established a novel strategy for screening regulators of environmental stress resistance based on the DNA methylome and discovered a new regulator, TagR. The TagR-WTA transporter regulatory pathway improved the resistance and antibiotic yield of strains and has the potential for wide application. Our research provides a new perspective on the optimization and reconstruction of industrial actinomycetes.

Maize transcription factor ZmNAC2 enhances osmotic stress tolerance in transgenic Arabidopsis

Osmotic stress seriously limits crop yield and quality. Among plant-specific transcription factors families, the NAC family of transcription factors is extensively involved in various growth, development and stress responses. Here we identified a maize NAC family transcription factor ZmNAC2 with inducible gene expression in response to osmotic stress. The subcellular localization showed that it was localized in the nucleus and overexpression of ZmNAC2 in Arabidopsis significantly promoted seed germination and elevated cotyledon greening under osmotic stress. ZmNAC2 also enhanced stomatal closure and decreased water loss in transgenic Arabidopsis. Overexpression of ZmNAC2 activated ROS scavenging and the transgenic lines accumulated less MDA and developed more lateral roots with drought or mannitol treatment. Further RNA-seq and qRT-PCR analysis showed that ZmNAC2 up-regulated a number of genes related to osmotic stress resistance, as well as plant hormone signaling genes. All together, ZmNAC2 enhances osmotic stress tolerance by regulating multiple physiological processes and molecular mechanisms, and exhibits potential as the target gene in crop breeding to increase osmotic stress resistance.

KaiC-like proteins contribute to stress resistance and biofilm formation in environmental Pseudomonas species.

KaiC is the central cog of the circadian clock in Cyanobacteria. Close homologues of this protein are widespread among nonphotosynthetic bacteria, but the function, interaction network, and mechanism of action of these proteins are still largely unknown. Here, we focus on KaiC homologues found in environmental Pseudomonas species. Using bioinformatics, we describe the distribution of this protein family in the genus and reveal a conserved interaction network comprising a histidine kinase and response regulator. We characterize experimentally the only KaiC homologue present in Pseudomonas putida KT2440 and Pseudomonas protegens CHA0. Through phenotypic assays and transcriptomics, we show that KaiC is involved in osmotic and oxidative stress resistance in P. putida and in biofilm production in both species. KaiC homologues are found in different phosphorylation states and physically interact with a cognate histidine kinase and response regulator. In contrast with cyanobacterial counterparts, the expression and phosphorylation of KaiC homologues do not correlate with light variations under 12:12 light: dark cycles in either Pseudomonas species, and KaiC itself is not required to support a light-driven behaviour in P. putida. Overall, this suggests that KaiC homologues in Pseudomonas species are involved in environmental stress resistance but not in responses to diurnal rhythms.

H3-T6SS of Pseudomonas aeruginosa PA14 contributes to environmental adaptation via secretion of a biofilm-promoting effector

Microbial species often occur in complex communities and exhibit intricate synergistic and antagonistic interactions. To avoid predation and compete for favorable niches, bacteria have evolved specialized protein secretion systems. The type VI secretion system (T6SS) is a versatile secretion system widely distributed among Gram-negative bacteria that translocates effectors into target cells or the extracellular milieu via various physiological processes. Pseudomonas aeruginosa is an opportunistic pathogen responsible for many diseases, and it has three independent T6SSs (H1-, H2-, and H3-T6SS). In this study, we found that the H3-T6SS of highly virulent P. aeruginosa PA14 is negatively regulated by OxyR and OmpR, which are global regulatory proteins of bacterial oxidative and acid stress. In addition, we identified a H3-T6SS effector PA14_33970, which is located upstream of VgrG3. PA14_33970 interacted directly with VgrG3 and translocated into host cells. Moreover, we found that H3-T6SS and PA14_33970 play crucial roles in oxidative, acid, and osmotic stress resistance, as well as in motility and biofilm formation. PA14_33970 was identified as a new T6SS effector promoting biofilm formation and thus named TepB. Furthermore, we found that TepB contributes to the virulence of P. aeruginosa PA14 toward Caenorhabditis elegans. Overall, our study indicates that H3-T6SS and its biofilm-promoting effector TepB are regulated by OxyR and OmpR, both of which are important for adaptation of P. aeruginosa PA14 to multiple stressors, providing insights into the regulatory mechanisms and roles of T6SSs in P. aeruginosa.

Osmotic stress resistance of different sorghum species affected by NaСl

Introduction. One of the most urgent issue of plant production which attracts the attention of many researchers and farmers, is salt tolerance of plants. Salinity has a negative effect, caused by the disruption of an osmotic balance of a cell that negatively affects water regime of plants. At the same time, plants experience growth inhibition and reduce their yield.The purpose of the study was to estimate resistance of different sorghum species to chloride salinity and to identify the most resistant genotypes.Methods. The study was carried out in the laboratory for plant physiology in 2018–2021. For the current study there has been carries out a modelling of a salt stress by a pure salt solution (concentration of 13 atm.) according to a conventional methodology, the control was distilled water.Results. There has been established the salinity stress effect on seed germination of different sorghum species. The values of germination energy and laboratory germination of grain sorghum were 53.1% and 62.0%; of sweet sorghum — 39.1% and 43.1; the values of Sudan grass — 30.1 and 33.5%, respectively. In the first and second groups — of highly resistant and resistant species (seed germination affected by salinity ranged from 61 to 100%) — were are 61% of grain sorghum genotypes, 56% of sugar sorghum genotypes and 6% of Sudan grass genotypes. There has been established a resistance degree and identified some features of the development of varieties with different degrees of resistance to this stress (length of sprouts and primary roots). Grain sorghum was found less susceptible to salinity stress of all studied species. Among grain sorghum samples, 9 genotypes have demonstrated the highest salinity resistance with a germination rate from 87.5 (Uch. 22/20) to 95.9% (Uch. 29/20). The maximum values were shown by the samples of Uch. 29/20 (95.95%), Uch. 20/20 (93.9%), Uch. 21/20 (93.8%), Jetta x Uch. 45/20 (91.5%) and Uch. 7/20 (90.8%), which indicated the ability to tolerate severe salinity concentration.

Differential impacts of salinity on antibiotic resistance genes during cattle manure stockpiling are linked to mobility potentials revealed by metagenomic sequencing

Livestock manure is an important source of antibiotic resistance genes (ARGs), and its salinity level can change during stockpiling. To understand how the salinity changes affect the fate of ARGs, cattle manure was adjusted of salinity and stockpiled in laboratory microcosms at low (0.3% salt), moderate (3.0%) and high salinity levels (10.0%) for 44 days. Amongst the five ARGs (tetO, blaTEM, sul1, tetM, and ermB) and the first-class integrase (intI1) monitored by qPCR, the relative abundance of tetO and blaTEM exhibited no clear trend in response to salinity levels, while that of sul1, tetM, ermB and intI1 showed clear downward trends over time at the lower salinity levels (0.3% and 3%) but not at the high salinity level (10%). Metagenomic contig construction of cattle manure samples revealed that sul1, tetM and ermB genes were more likely to associate with mobile genetic elements (MGEs) than tetO and blaTEM, suggesting that their slower decay at higher salinity levels was either caused by horizontal gene transfer or co-selection of ARGs and osmotic stress resistant determinants. Further analysis of metagenomic contigs showed that osmotic stress resistance can also be located on MGEs or in conjunction with ARGs.

An integrated physiology, cytology, and proteomics analysis reveals a network of sugarcane protoplast responses to enzymolysis.

The protoplast experimental system eis an effective tool for functional genomics and cell fusion breeding. However, the physiological and molecular mechanisms of protoplast response to enzymolysis are not clear, which has become a major obstacle to protoplast regeneration. Here, we used physiological, cytological, proteomics and gene expression analysis to compare the young leaves of sugarcane and enzymolized protoplasts. After enzymatic digestion, we obtained protoplasts with viability of > 90%. Meanwhile, the content of malondialdehyde, an oxidation product, increased in the protoplasts following enzymolysis, and the activity of antioxidant enzymes, such as peroxidase (POD), catalase (CAT), acid peroxidase (APX), and O2-, significantly decreased. Cytologic analysis results showed that, post enzymolysis, the cell membranes were perforated to different degrees, the nuclear activity was weakened, the nucleolus structure was not obvious, and the microtubules depolymerized and formed several short rod-like structures in protoplasts. In this study, a proteomics approaches was used to identify proteins of protoplasts in response to the enzymatic digestion process. GO, KEGG, and KOG enrichment analyses revealed that the abundant proteins were mainly involved in bioenergetic metabolism, cellular processes, osmotic stress, and redox homeostasis of protoplasts, which allow for protein biosynthesis or degradation. RT-qPCR analysis revealed that the expression of osmotic stress resistance genes, such as DREB, WRKY, MAPK4, and NAC, was upregulated, while that of key regeneration genes, such as CyclinD3, CyclinA, CyclinB, Cdc2, PSK, CESA, and GAUT, was significantly downregulated in the protoplasts. Hierarchical clustering and identification of redox proteins and oxidation products showed that these proteins were involved in dynamic networks in response to oxidative stress after enzymolysis. Our findings can facilitate the development of a standard system to produce regenerated protoplasts using molecular markers and antibody detection of enzymolysis.

Achog1 is required for the asexual sporulation, stress responses and pigmentation of Aspergillus cristatus.

Aspergillus cristatus is the dominant fungus during the fermentation of Fuzhuan brick tea; hypotonic conditions only induce its sexual development to produce ascospores, while hypertonic conditions only induce its asexual development to produce conidia, indicating that osmotic stress can regulate spore production in A. cristatus. However, the underlying regulatory mechanism is unclear. In this study, the role of Achog1, which is homologous to hog1 from Saccharomyces cerevisiae, in sporulation, different kinds of stress responses and pigment production was investigated. Deletion mutants of Achog1 were obtained by homologous recombination. Phenotypic observations showed that the time required to produce conidia was delayed, and the number of conidia produced was significantly reduced in the deletion mutants of Achog1 in hypertonic media, indicating that Achog1 plays a positive role in asexual development. Stress sensitivity tests showed that ΔAchog1 strains were sensitive to hyperosmolarity, and the order of the sensitivity of ΔAchog1 to different osmotic regulators was 3 M sucrose >3 M NaCl >3 M sorbitol. Moreover, the deletion mutants were sensitive to high oxidative stress. pH sensitivity tests indicated that Achog1 inhibited the growth of A. cristatus under alkaline stress. Additionally, pigmentation was decreased in the Achog1 deletion mutants compared with the WT. All the above developmental defects were reversed by the reintroduction of the Achog1 gene in ΔAchog1. Pull-down and LC-MS/MS analysis showed that the expression levels of proteins interacting with Achog1 were significantly different under low and high osmotic stress, and proteins related to conidial development were present only in the cultures treated with hyperosmotic stress. Transcription profiling data showed that Achog1 suppressed the expression of several genes related to asexual development, osmotic and oxidative stress resistance. On the basis of gene knockout, pull-down mass spectrometry and RNA-seq analyses, a regulatory pathway for Achog1 was roughly identified in A. cristatus.

Genome mining reveals abiotic stress resistance genes in plant genomes acquired from microbes via HGT.

Colonization by beneficial microbes can enhance plant tolerance to abiotic stresses. However, there are still many unknown fields regarding the beneficial plant-microbe interactions. In this study, we have assessed the amount or impact of horizontal gene transfer (HGT)-derived genes in plants that have potentials to confer abiotic stress resistance. We have identified a total of 235 gene entries in fourteen high-quality plant genomes belonging to phyla Chlorophyta and Streptophyta that confer resistance against a wide range of abiotic pressures acquired from microbes through independent HGTs. These genes encode proteins contributed to toxic metal resistance (e.g., ChrA, CopA, CorA), osmotic and drought stress resistance (e.g., Na+/proline symporter, potassium/proton antiporter), acid resistance (e.g., PcxA, ArcA, YhdG), heat and cold stress resistance (e.g., DnaJ, Hsp20, CspA), oxidative stress resistance (e.g., GST, PoxA, glutaredoxin), DNA damage resistance (e.g., Rad25, Rad51, UvrD), and organic pollutant resistance (e.g., CytP450, laccase, CbbY). Phylogenetic analyses have supported the HGT inferences as the plant lineages are all clustering closely with distant microbial lineages. Deep-learning-based protein structure prediction and analyses, in combination with expression assessment based on codon adaption index (CAI) further corroborated the functionality and expressivity of the HGT genes in plant genomes. A case-study applying fold comparison and molecular dynamics (MD) of the HGT-driven CytP450 gave a more detailed illustration on the resemblance and evolutionary linkage between the plant recipient and microbial donor sequences. Together, the microbe-originated HGT genes identified in plant genomes and their participation in abiotic pressures resistance indicate a more profound impact of HGT on the adaptive evolution of plants.

The characterization and expression analysis under stress conditions of PCST1 in Arabidopsis

ABSTRACT Analysis of PCST1 expression characteristics and the role of PCST1 in response to osmotic stress in Arabidopsis thaliana. The structure of PCST1 was analyzed using Bioinformatics method. Real-time PCR, GUS tissue localization and subcellular localization were adopted to analyze the expression pattern of PCST1 in Arabidopsis. To validate the transgenic positive strain of PCST1 using Real-time PCR, overexpression experiments were performed in wild type. Full-length cDNA was cloned and connected into a binary vector with 35S promoter, and the construction was transformed into wild type. With NaCl and mannitol treatments, the germination rate, green leaves rate, physiological indexes were carried out and counted in Arabidopsis with overexpression of PCST1 and T-DNA insertion mutants. The molecular mechanism of PCST1 in response to osmotic stress in Arabidopsis was analyzed. Based on the bioinformatic analysis, PCST1 is a hydrophobin with 403 amino acids, and the molecular weight is 45.3236 KDa. It contains only the START (the lipid/sterol – binding StAR – related lipid transfer protein domains) conservative domain. PCST1 possesses phosphatidylcholine binding sites and transmembrane region. Expression pattern analysis showed that expression of PCST1 increased with time. The PCST1 widely expressed in Arabidopsis, including roots, axils of stem leaves, flowers (sepal, conductive tissue of the petal, thrum, anther and stigmas), and the top and basal parts of the siliquas. It mainly localized in cell membrane. The overexpression of PCST1 enhanced the sensitivity to osmotic stress in Arabidopsis based on the germination rate. While expression of PCST1 decreased, and the sensitivity to osmotic stress had no obvious change in Arabidopsis. Its molecular mechanism study showed, that PCST1 response to osmotic stress resistance by regulating the proline, betaine synthesis, as well as the expression of key genes SOS, NCED, CIPK. PCST1 is composed of 403 amino acids. The START conservative domain, a transmembrane structure, the phosphatidyl choline binding sites are contained in PCST1. It is localized in cytoplasmic membrane. The PCST1 widely expressed in the root, leaf, flower and siliquas. NaCl and mannitol suppressed the expression of PCST1 and PCST1 can negatively control action of Arabidopsis in the osmotic stress. PCST1 regulates the synthetic pathway of proline, betaine and the expression of SOS, NCED and CIPK in response to the osmotic stress resistance.

Abscisic acid induces the expression of AsKIN during the recovery period of garlic cryopreservation.

Abscisic acid induced the expression of AsKIN during the recovery period of garlic cryopreservation. AsKIN was identified as a gene involved in cold and osmotic stress resistance. Cryopreservation has been proven to be effective in removing viruses from garlic. However, oxidative damage in cryopreservation has a significant impact on the survival after preservation. Abscisic acid (ABA) has been shown to reduce oxidative stress and promote the survival after cryopreservation. However, it is not clear which genes play important roles in this process. In this study, we added ABA to the dehydration step and analyzed the transcriptomic divergences between the ABA-treated group and the control group in three cryogenic steps (dehydration, unloading and recovery). By short time-series expression miner (STEM) analysis and weighted gene co-expression network analysis (WGCNA), the recovery step was identified as the period of significant changes in gene expression levels in cryopreservation. The addition of ABA promoted the upregulated expression of microtubule-related genes in the recovery step. We further identified AsKIN as a hub gene in the recovery step and verified its function. The results showed that overexpression of AsKIN enhanced the tolerance of Arabidopsis to oxidative stress in cryopreservation, influenced the expression of genes in response to cold and osmotic stress and promoted plant growth after stress. The AsKIN gene is likely to be involved in the plant response to cold stress and osmotic stress. These results reveal the molecular mechanisms of ABA in cryopreservation and elucidate the potential biological functions of the kinesin-14 subfamily.

Rounding out cyclic dinucleotide signaling in Clostridioides difficile: A role and a mechanism for c-di-AMP.

The second messenger c-di-AMP contributes to various homeostatic and stress responses in bacteria. In this issue of Science Signaling, Oberkampf et al. have identified it as a mediator of osmotic stress and bile salt resistance in the opportunistic pathogen Clostridioides difficile, with additional roles in cell wall homeostasis and biofilm formation.