Dehydration Response Research Articles

Genome-Wide Analysis of AP2/ERF Gene Superfamily in Ramie (Boehmeria nivea L.) Revealed Their Synergistic Roles in Regulating Abiotic Stress Resistance and Ramet Development

AP2/ERF transcription factors (TFs) are one of the largest superfamilies in plants, and play vital roles in growth and response to biotic/abiotic stresses. Although the AP2/ERF family has been extensively characterized in many species, very little is known about this family in ramie (Boehmeria nivea L.). In this study, 138 AP2/ERF TFs were identified from the ramie genome and were grouped into five subfamilies, including the AP2 (19), RAV (5), Soloist (1), ERF (77), and DREB (36). Unique motifs were found in the DREB/ERF subfamily members, implying significance to the AP2/ERF TF functions in these evolutionary branches. Segmental duplication events were found to play predominant roles in the BnAP2/ERF TF family expansion. Light-, stress-, and phytohormone-responsive elements were identified in the promoter region of BnAP2/ERF genes, with abscisic acid response elements (ABRE), methyl jasmonate response elements, and the dehydration response element (DRE) being dominant. The integrated transcriptome and quantitative real-time PCR (qPCR) revealed 12 key BnAP2/ERF genes positively responding to waterlogging. Five of the genes are also involved in ramet development, with two (BnERF-30 and BnERF-32) further showing multifunctional roles. The protein interaction prediction analysis further verified their crosstalk mechanism in coordinating waterlogging resistance and ramet development. Our study provides new insights into the presence of AP2/ERF TFs in ramie, and provides candidate AP2/ERF TFs for further studies on breeding varieties with coupling between water stress tolerance and high yield.

Dehydration response in Stylosanthes scabra: Transcriptional, biochemical, and physiological modulations.

Stylosanthes scabra, popularly known as stylo, is native to the Brazilian Caatinga semiarid region and stands out as a drought-tolerant shrub forage crop. This work provides information about the plant response during the first 48 h of water deficit, followed by a rehydration treatment. Besides root transcriptomics data, 13 physiological or biochemical parameters were scrutinized. Additionally, RNA-Seq annotated transcripts not associated with the "Viridiplantae" clade were taxonomically categorized. It was found that S. scabra quickly perceives and recovers from the oscillations of the imposed water regime. Physiologically, mechanisms that minimize evapotranspiration or protect the photosynthetic apparatus stood out. Biochemically, it was found that the root tissue invests in synthesizing compounds that can act as osmolytes (proline and sugars), emphasizing the importance of osmoregulation to water deficit acclimation. Consistently, transcriptome and qPCR analyses showed that a set of enriched biological processes with upregulated (UR) transcripts were involved in protective functions against reactive oxygen species or encoding enzymes of important metabolic pathways, which might contribute to S. scabra response to water deficit. Additionally, several UR kinases and transcription factors were identified. Finally, in an innovative approach, some naturally occurring microbial groups (such as Schizosaccharomyces, Bradyrhizobium, etc.) were identified in the S. scabra roots. This study reveals insights into the physiological, biochemical, and molecular mechanisms underlying the S. scabra response to water deficit and provides candidate genes that may be useful in developing drought-tolerant crop varieties through biotechnological applications.

Natural polymorphism of ZmICE1 contributes to amino acid metabolism that impacts cold tolerance in maize.

Cold stress negatively affects maize (Zea mays L.) growth, development and yield. Metabolic adjustments contribute to the adaptation of maize under cold stress. We show here that the transcription factor INDUCER OF CBF EXPRESSION 1 (ZmICE1) plays a prominent role in reprogramming amino acid metabolome and COLD-RESPONSIVE (COR) genes during cold stress in maize. Derivatives of amino acids glutamate/asparagine (Glu/Asn) induce a burst of mitochondrial reactive oxygen species, which suppress the cold-mediated induction of DEHYDRATION RESPONSE ELEMENT-BINDING PROTEIN 1 (ZmDREB1) genes and impair cold tolerance. ZmICE1 blocks this negative regulation of cold tolerance by directly repressing the expression of the key Glu/Asn biosynthesis genes, ASPARAGINE SYNTHETASEs. Moreover, ZmICE1 directly regulates the expression of DREB1s. Natural variation at the ZmICE1 promoter determines the binding affinity of the transcriptional activator ZmMYB39, a positive regulator of cold tolerance in maize, resulting in different degrees of ZmICE1 transcription and cold tolerance across inbred lines. This study thus unravels a mechanism of cold tolerance in maize and provides potential targets for engineering cold-tolerant varieties.

Genome-wide characterization of C2H2 zinc-finger gene family provides insight into the mechanisms and evolution of the dehydration-rehydration responses in Physcomitrium and Arabidopsis.

Dehydration tolerance is a vital factor for land plant evolution and world agricultural production. Numerous studies enlightened that the plant-specific C2H2-type zinc-finger proteins (C2H2-ZFPs) as master regulators played pivotal roles in the abiotic stress responses of plants. However, a comprehensive understanding of the evolution of C2H2-ZFPs in terrestrial plants and its regulatory mechanism in dehydration and rehydration response remains a mystery. In this study, the genome-wide identification of C2H2-ZFP genes revealed 549 homologs in the representatives of terrestrial plant lineages from liverwort to angiosperms. Based on the characteristics of the conserved C2H2-ZF domains, four major C2H2-ZF types (M-, Z-, Q-, and D-type) were identified in the C2H2-ZFPs, with the dominants of M-type in all selected species and followed by Z-type in non-seed plants and Q-type in seed plants, respectively. Phylogenetic analyses of the identified C2H2-ZFPs supported four major groups in the land plant representatives, among which the members from the desiccation-tolerant Physcomitrium patens and the dehydration-sensitive Arabidopsis thaliana displayed different topological relationships in the phylogenies reconstructed for a single species. C2H2-ZFPs clustered in the same subclades shared similar features in their conserved domains and gene structures. Approximately, 81% of the C2H2-ZFP promoters of all 549 identified C2H2-ZFPs harbored the conserved ABA-responsive elements (ABREs) and/or dehydration-responsive elements (DREs). Comparative transcriptomic analyses showed that 50 PpZFPs and 56 AtZFPs significantly changed their transcripts abundance. Interestingly, most of the dehydration- and rehydration-responsive PpZPFs and AtZFPs had been predicted to contain the ABRE and DRE elements in their promoter regions and with over half of which phylogenetically belonging to group III. The differences in the expression patterns of C2H2-ZFPs in responses to dehydration and rehydration between P. patens and A. thaliana reflected their different strategies to adapt to dehydration. The identified candidate PpZFPs were specifically induced by moderate dehydration and reached the peak transcript abundance in severe dehydration. Our study lays the foundations for further functional investigation of C2H2-ZFPs in dehydration responses from an evolutionary perspective in land plants. The findings will provide us with genetic resources and potential targets for drought tolerance breeding in crops and beyond.

Phenotypic and transcriptomic analysis reveals early stress responses in transgenic rice expressing Arabidopsis DREB1a.

Overexpression of Arabidopsis dehydration response element binding 1a (DREB1a) is a well‐known approach for developing salinity, cold and/or drought stress tolerance. However, understanding of the genetic mechanisms associated with DREB1a expression in rice is generally limited. In this study, DREB1a‐associated early responses were investigated in a transgenic rice line harboring cold‐inducible DREB1a at a gene stacked locus. Although the function of other genes in the stacked locus was not relevant to stress tolerance, this study demonstrates DREB1a can be co‐localized with other genes for multigenic trait enhancement. As expected, the transgenic lines displayed improved tolerance to salinity stress and water withholding as compared with non‐transgenic controls. RNA sequencing and transcriptome analysis showed upregulation of complex transcriptional networks and metabolic reprogramming as DREB1a expression led to the upregulation of multiple transcription factor gene families, suppression of photosynthesis, and induction of secondary metabolism. In addition to the detection of previously described mechanisms such as production of protective molecules, potentially novel pathways were also revealed. These include jasmonate, auxin, and ethylene signaling, induction of JAZ and WRKY regulons, trehalose synthesis, and polyamine catabolism. These genes regulate various stress responses and ensure timely attenuation of the stress signal. Furthermore, genes associated with heat stress response were downregulated in DREB1a expressing lines, suggesting antagonism between heat and dehydration stress response pathways. In summary, through a complex transcriptional network, multiple stress signaling pathways are induced by DREB1a that presumably lead to early perception and prompt response toward stress tolerance as well as attenuation of the stress signal to prevent deleterious effects of the runoff response.

Isolation and Functional Characterization of Soybean BES1/BZR1 Homolog 3-Like 1 (GmBEH3L1) Associated with Dehydration Sensitivity and Brassinosteroid Signaling in Arabidopsis thaliana

Brassinosteroid (BR) is an important steroid hormone that regulates plant development, abscisic acid (ABA) signaling, and responses to abiotic stress. We previously demonstrated that BEH3 (BES1/BZR1 Homolog 3) of Arabidopsis thaliana regulates dehydration and ABA responses by mediating proline metabolism. Furthermore, BEH3 negatively regulates BR-mediated hypocotyl elongation in dark-grown seedlings. However, the roles of BEH3 ortholog genes in the osmotic stress response of plants have remained largely unknown. Here, GmBEH3L1 (Glycine max BEH3-Like 1), a soybean (G. max) ortholog of the BEH3 gene of A. thaliana, was isolated and functionally characterized. GmBEH3L1 is induced by ABA, dehydration, and drought conditions. The GmBEH3L1-overexpressing transgenic lines (GmBEH3L1-OE/beh3) with the beh3 mutant background have ABA- and dehydration-sensitive phenotypes during early seedling growth, implying that GmBEH3L1 is involved in both osmotic stress and ABA sensitivity as a negative regulator in A. thaliana. Consistent with these results, GmBEH3L1-OE/beh3 complemental lines exhibit decreased expression levels of ABA- or dehydration-inducible genes. Under darkness, GmBEH3L1-OE/beh3 complemental lines display a short hypocotyl length compared to the beh3 mutant, indicating that GmBEH3L1 is linked to BR signaling. Together, our data suggest that GmBEH3L1 participates negatively in ABA and dehydration responses through BR signaling.

The two-component response regulator OrrA confers dehydration tolerance by regulating avaKa expression in the cyanobacterium Anabaena sp. strain PCC 7120.

The cyanobacterium Anabaena sp. strain PCC 7120 exhibits dehydration tolerance. The regulation of gene expression in response to dehydration is crucial for the acquisition of dehydration tolerance, but the molecular mechanisms underlying dehydration responses remain unknown. In this study, the functions of the response regulator OrrA in the regulation of salt and dehydration responses were investigated. Disruption of orrA abolished or diminished the induction of hundreds of genes in response to salt stress and dehydration. Thus, OrrA is a principal regulator of both stress responses. In particular, OrrA plays a crucial role in dehydration tolerance because an orrA disruptant completely lost the ability to regrow after dehydration. Moreover, in the OrrA regulon, avaKa encoding a protein of unknown function was revealed to be indispensable for dehydration tolerance. OrrA and AvaK are conserved among the terrestrial cyanobacteria, suggesting their conserved functions in dehydration tolerance in cyanobacteria.

Evidence for Light and Tissue Specific Regulation of Genes Involved in Fructan Metabolism in Agave tequilana.

Plant Glycoside Hydrolase Family 32 (PGHF32) contains the fructosyltransferases and fructan exohydrolase enzymes responsible for fructan metabolism, in addition to closely related vacuolar and cell wall acid invertases. Agave species produce complex and dynamic fructan molecules (agavins) requiring 4 different fructosyltransferase activities (1-SST, 1-FFT, 6G-FFT and 6-SFT) for their synthesis. Combined analysis of RNAseq and genome data for A. tequilana led to the characterization of the genes encoding 3 fructosyltransferases for this species and support the hypothesis that no separate 6-SFT type enzyme exists in A. tequilana, suggesting that at least one of the fructosyltransferases identified may have multiple enzymatic activities. Structures for PGHF32 genes varied for A. tequilana and between other plant species but were conserved for different enzyme types within a species. The observed patterns are consistent with the formation of distinct gene structures by intron loss. Promoter analysis of the PGHF32 genes identified abundant putative regulatory motifs for light regulation and tissue-specific expression, and these regulatory mechanisms were confirmed experimentally for leaf tissue. Motifs for phytohormone response, carbohydrate metabolism and dehydration responses were also uncovered. Based on the regulatory motifs, full-length cDNAs for MYB, GATA, DOF and GBF transcription factors were identified and their phylogenetic distribution determined by comparison with other plant species. In silico expression analysis for the selected transcription factors revealed both tissue-specific and developmental patterns of expression, allowing candidates to be identified for detailed analysis of the regulation of fructan metabolism in A. tequilana at the molecular level.

Role of RcTINY2 in the Regulation of Drought and Salt Stress Response in Arabidopsis and Rose

In plants, transcription factors (TFs) belonging to the APETALA2/ethylene responsive factor (AP2/ERF) superfamily regulate a variety of life processes, including germination, maturation, and stress response. In the present study, RcTINY2, a novel dehydration response element binding protein (DREB) belonging to the A-4 group, was identified and characterized in rose (Rosa chinensis). RcTINY2 shares high homology with AtTINY2 of Arabidopsis (Arabidopsis thaliana), with several abiotic stress-responsive cis-regulatory elements. Transcript levels of RcTINY2 were induced by exposure to abscisic acid (ABA) in rose leaves and repressed by exposure to ABA, polyethylene glycol (PEG), and NaCl in rose roots. RcTINY2 is localized in the nucleus and showed transcriptional activation in yeast cells. Further analysis of transgenic Arabidopsis demonstrated that plants overexpressing RcTINY2 displayed increased ABA, PEG, and NaCl sensitivity in both germinating seeds and seedlings with reduced root growth and lateral root number. RcTINY2-silenced rose plants were found to be increasingly intolerant of both drought and salt stress. Furthermore, the transcript levels of several ABA- and abiotic stress-related genes were suppressed in RcTINY2-silenced rose plants. The results suggested that RcTINY2 may serve as a candidate gene for genetic improvement of abiotic stress tolerance in rose and other plant species.

TaNF-YA7-5B, a gene encoding nuclear factor Y (NF–Y) subunit A in Triticum aestivum, confers plant tolerance to PEG-inducing dehydration simulating drought through modulating osmotic stress-associated physiological processes

Members of nuclear factor-Y (NF–Y) transcription factors play important roles in regulating physiological processes associated with abiotic stress responses. In this study, we characterized TaNF-YA7-5B, a gene encoding wheat NY-YA subunit, in mediating plant adaptation to PEG-inducing dehydration stress. TaNF-YA7-5B shares high similarities to its homologs across various plant species. The TaNF-YA7-5B protein is specified by its conserved domains as plant NF-YA members and targets onto nucleus after endoplasmic reticulum assortment. Yeast two-hybrid assays indicated that TaNF-YA7-5B interacts with TaNF-YB2 and TaNF-YC7, two members of NF-YB and NF-YC subfamilies, suggesting a heterotrimer constituted by TaNF-YA7-5B and above NF-YB and -YC partners. TaNF-YA7-5B displayed induced expression upon drought and whose PEG-inducing dehydration-elevated transcripts were restored under normal recovery condition, suggesting its involvement in plant PEG-inducing dehydration response through modifying transcription efficiency. Overexpressing TaNF-YA7-5B conferred plant improved growth under PEG-inducing dehydration, which was ascribed largely to the gene function in regulating stomata closing and leaf water retention, osmolyte biosynthesis, and cellular ROS homeostasis. The expression of P5CS gene TaP5CS2 and antioxidant enzyme (AE) genes, namely, TaSOD3, TaCAT1, and TaPOD4, was upregulated and downregulated in lines with overexpression and knockdown of TaNF-YA7-5B, respectively; transgene analysis on them validated their functions in positively regulating proline accumulation and ROS scavenging under PEG-inducing dehydration. RNA-seq analysis revealed modified transcription of numerous genes underlying TaNF-YA7-5B enriched by GO terms ‘biological process’, ‘cellular components’, and ‘molecular function’. Therefore, TaNF-YA7-5B is a crucial regulator for plant drought adaptation through comprehensively integrating diverse physiological processes associated with drought acclimation.

Water intake, thirst, and copeptin responses to two dehydrating stimuli in lean men and men with obesity.

Physiological systems responsible for water homeostasis and energy metabolism are interconnected. This study hypothesized altered responses to dehydration including thirst, ad libitum water intake, and copeptin in men with obesity. Forty-two men (22 lean and 20 with obesity) were stimulated by a 2-hour hypertonic saline infusion and a 24-hour water deprivation. In each dehydrating condition, thirst, ad libitum water intake after dehydration, and urinary and hormonal responses including copeptin were assessed. After each dehydration condition, ad libitum water intake was similar between both groups (p > 0.05); however, those with obesity reported feeling less thirsty (p < 0.05) and had decreased copeptin response and higher urinary sodium concentrations when stressed (p < 0.05). Angiotensin II, aldosterone, atrial and brain natriuretic peptides, and apelin concentrations did not differ by adiposity group and did not explain the different thirst or copeptin responses in men with obesity. However, leptin was associated with copeptin response in lean individuals during the hypertonic saline infusion (p < 0.05), but the relationship was diminished in those with obesity. Diminished thirst and copeptin responses are part of the obesity phenotype and may be influenced by leptin. Adiposity may impact pathways regulating thirst and vasopressin release, warranting further investigation.

Microorganisms in Plant Growth and Development: Roles in Abiotic Stress Tolerance and Secondary Metabolites Secretion.

Crops aimed at feeding an exponentially growing population are often exposed to a variety of harsh environmental factors. Although plants have evolved ways of adjusting their metabolism and some have also been engineered to tolerate stressful environments, there is still a shortage of food supply. An alternative approach is to explore the possibility of using rhizosphere microorganisms in the mitigation of abiotic stress and hopefully improve food production. Several studies have shown that rhizobacteria and mycorrhizae organisms can help improve stress tolerance by enhancing plant growth; stimulating the production of phytohormones, siderophores, and solubilizing phosphates; lowering ethylene levels; and upregulating the expression of dehydration response and antioxidant genes. This article shows the secretion of secondary metabolites as an additional mechanism employed by microorganisms against abiotic stress. The understanding of these mechanisms will help improve the efficacy of plant-growth-promoting microorganisms.

Transcriptome Analysis of Moso Bamboo (Phyllostachys edulis) Reveals Candidate Genes Involved in Response to Dehydration and Cold Stresses.

Bamboo (Bambusoideae) belongs to the grass family (Poaceae) and has been utilized as one of the most important nontimber forest resources in the world. Moso bamboo (Phyllostachys edulis) is a large woody bamboo with high ecological and economic values. Global climate change brings potential challenges to the normal growth of moso bamboo, and hence its production. Despite the release of moso bamboo genome sequence, the knowledge on genome-wide responses to abiotic stress is still limited. In this study, we generated a transcriptome data set with respect to dehydration and cold responses of moso bamboo using RNA-seq technology. The differentially expressed genes (DEGs) under treatments of dehydration and cold stresses were identified. By combining comprehensive gene ontology (GO) analysis, time-series analysis, and co-expression analysis, candidate genes involved in dehydration and cold responses were identified, which encode abscisic acid (ABA)/water deficit stress (WDS)-induced protein, late embryogenesis abundant (LEA) protein, 9-cis-epoxycarotenoid dioxygenase (NCED), anti-oxidation enzymes, transcription factors, etc. Additionally, we used PeLEA14, a dehydration-induced gene encoding an “atypical” LEA protein, as an example to validate the function of the identified stress-related gene in tolerance to abiotic stresses, such as drought and salt. In this study, we provided a valuable genomic resource for future excavation of key genes involved in abiotic stress responses and genetic improvement of moso bamboo to meet the requirement for environmental resilience and sustainable production.

Comparative proteomic analysis on chloroplast proteins provides new insights into the effects of low temperature in sugar beet

BackgroundLow temperature, which is one of the main environmental factors that limits geographical distribution and sucrose yield, is a common abiotic stress during the growth and development of sugar beet. As a regulatory hub of plant response to abiotic stress, activity in the chloroplasts is related to many molecular and physiological processes, particularly in response to low temperature stress.ResultsThe contents of chlorophyll (Chl) and malondialdehyde (MDA), relative electrical conductivity (REL), and superoxide dismutase (SOD) activity were measured. The results showed that sugar beet could manage low temperature stress by regulating the levels of Chl, REL and MDA, and the activity of SOD. The physiological responses indicated that sugar beets respond positively to low temperature treatments and are not significantly damaged. Moreover, to determine the precise time to response low temperature in sugar beet, well-known abiotic stresses-responsive transcript factor family, namely DEHYDRATION RESPONSIVE ELEMENT BINDING PROTEIN (DREB), was selected as the marker gene. The results of phylogenetic analyses showed that BvDREBA1 and BvDREBA4 were in the same branch as the cold- and drought-responsive AtDREB gene. In addition, the expression of BvDREBs reached its maximum level at 24 h after low temperature by RNA-Seq and qRT-PCR analysis. Furthermore, the changes in chloroplast proteome after low temperature at 24 h were detected using a label-free technique. A total of 416 differentially expressed proteins were identified. GO enrichment analysis showed that 16 GO terms were significantly enriched, particularly chloroplast stroma, chloroplast envelope, and chloroplast thylakoid membrane. It is notable that the transport of photosynthetic proteins (BvLTD and BvTOC100), the formation of starch granules (BvPU1, BvISA3, and BvGWD3) and the scavenging of reactive oxygen species (BvCu/Zn-SOD, BvCAT, BvPrx, and BvTrx) were the pathways used by sugar beets to respond to low temperatures at an early stage.ConclusionsThese results provide a preliminarily analysis of how chloroplasts of sugar beet respond to low temperature stress at the translational level and provide a theoretical basis for breeding low temperature resistant varieties of sugar beet.

Comparison of End-Tidal Carbon Dioxide (ETCO2) Gradient and Vena Cava Collapsibility Index (VCCI) in Response to Intravenous Fluid Therapy in Patients with Moderate and Severe Dehydration and Acute Gastroenteritis

Acute gastroenteritis (AGE) is one of the most common clinical diagnoses globally, and dehydration in severe AGE cases can cause severe morbidity and mortality. Depending on the metabolic acidosis that occurs in dehydration, the respiratory rate per minute is increased, and the carbon dioxide pressure in the arterial blood is decreased. This condition correlates with end-tidal carbon dioxide (ETCO2). Therefore, this study primarily aims to evaluate whether ETCO2 measurement has a role in detecting metabolic fluid deficit, dehydration level, and regression in dehydration level after fluid replacement and its correlation with Vena Cava Collapsibility Index (VCCI). This study included spontaneously breathing patients admitted to the emergency department of a tertiary training and research hospital with symptoms of AGE and were thought to be moderately (6.0%-9.0%) and severely (>10.0%) dehydrated according to the Primary Options of Acute Care (POAC) Clinical Dehydration Scale. After the first evaluation, the patients' vital signs, ETCO2 values, diameters of the inferior vena cava (IVC) in inspiration and expiration, and VCCI were measured and recorded. These measurements were repeated after intravenous (IV) fluid replacement, and finally, a comparison was made between the measurements. A total of 49 patients, as 16 male (32.7%) and 33 female (67.3%), were included in the study. The mean fluid replacement value was calculated as 664.29 (SD = 259.41) ml. The mean increase in ETCO2 was 3.653 (SD = 2.554) mmHg (P <.001). The mean increase in inferior vena cava expirium (IVCexp) was calculated as 0.402 (SD = 0.280) cm (P <.001) and the mean increase in inferior vena cava inspirium (IVCinsp) as 0.476 (SD = 0.306) cm (P <.001). The VCCI (%) decreased by 12.556 (SD = 13.683) (P <.001). Post-replacement vital signs, ETCO2, and VCCI correlations of the patients were examined and no significant correlation was found between ETCO2 and VCCI (%). As a result of this study, a receiver operating characteristic (ROC) curve was established for the ETCO2 values predicting the level of dehydration and fluid response, and the area under the curve was calculated as 0.748. However, to classify the patient as moderately dehydrated, the ETCO2 cutoff value was determined as 28.5mmHg. The sensitivity and specificity of ETCO2 levels were 71.43% and 74.29% in evaluating the level of dehydration, and no correlation was found with VCCI, which is known to have high sensitivity and specificity in previous studies in determining the level of dehydration and fluid response. Hence, VCCI measurement made through ultrasonography (USG) is a method that should be preferred more in determining the level of dehydration. Nevertheless, as per the results of this study, swift ETCO2 measurements may be helpful in monitoring the change in the degree of dehydration with treatment in patients who were admitted to the emergency department with dehydration findings and were administered IV fluid replacement therapy.

Physiological and multi-omics responses of Neoporphyra haitanensis to dehydration-rehydration cycles

BackgroundSeaweeds in the upper intertidal zone experience extreme desiccation during low tide, followed by rapid rehydration during high tide. Porphyra sensu lato are typical upper intertidal seaweeds. Therefore, it is valuable to investigate the adaptive mechanisms of seaweed in response to dehydration-rehydration stress.ResultsA reduction in photosynthetic capacity and cell shrinkage were observed when N. haitanensis was dehydrated, and such changes were ameliorated once rehydrated. And the rate and extent of rehydration were affected by the air flow speed, water content before rehydration, and storage temperature and time. Rapid dehydration at high air-flow speed and storage at − 20 °C with water content of 10% caused less damage to N. haitanensis and better-protected cell activity. Moreover, proteomic and metabolomic analyses revealed the abundance members of the differentially expressed proteins (DEPs) and differentially abundant metabolites (DAMs) mainly involved in antioxidant system and osmotic regulation. The ascorbic acid-glutathione coupled with polyamine antioxidant system was enhanced in the dehydration response of N. haitanensis. The increased soluble sugar content, the accumulated polyols, but hardly changed (iso)floridoside and insignificant amount of sucrose during dehydration indicated that polyols as energetically cheaper organic osmolytes might help resist desiccation. Interestingly, the recovery of DAMs and DEPs upon rehydration was fast.ConclusionsOur research results revealed that rapid dehydration and storage at − 20 °C were beneficial for recovery of N. haitanensis. And the strategy to resist dehydration was strongly directed toward antioxidant activation and osmotic regulation. This work provided valuable insights into physiological changes and adaptative mechanism in desiccation, which can be applied for seaweed farming.

Identification and validation of the wound and insect bite early inducible promoter from Arabidopsis thaliana.

The online version contains supplementary material available at 10.1007/s13205-022-03143-0.

Stability of Intracellular Protein Concentration under Extreme Osmotic Challenge.

Cell volume (CV) regulation is typically studied in short-term experiments to avoid complications resulting from cell growth and division. By combining quantitative phase imaging (by transport-of-intensity equation) with CV measurements (by the exclusion of an external absorbing dye), we were able to monitor the intracellular protein concentration (PC) in HeLa and 3T3 cells for up to 48 h. Long-term PC remained stable in solutions with osmolarities ranging from one-third to almost twice the normal. When cells were subjected to extreme hypoosmolarity (one-quarter of normal), their PC did not decrease as one might expect, but increased; a similar dehydration response was observed at high concentrations of ionophore gramicidin. Highly dilute media, or even moderately dilute in the presence of cytochalasin, caused segregation of water into large protein-free vacuoles, while the surrounding cytoplasm remained at normal density. These results suggest that: (1) dehydration is a standard cellular response to severe stress; (2) the cytoplasm resists prolonged dilution. In an attempt to investigate the mechanism behind the homeostasis of PC, we tested the inhibitors of the protein kinase complex mTOR and the volume-regulated anion channels (VRAC). The initial results did not fully elucidate whether these elements are directly involved in PC maintenance.

프롤린 함량 증가 및 내건성 강화 관련 새로운 RING-Type E3 유비퀴틴 리가아제 애기장대 atrzf1 돌연변이체의 생리적 기능 연구

The covalent attachment of ubiquitin to proteins plays a fundamental role in the regulation of cellular function through biological events involving abiotic or biotic stress responses, immune responses, and apoptosis. Here, we characterize the biological function of the <italic>Arabidopsis thaliana</italic> RING Zinc Finger 1 (AtRZF1) in dehydration response. <italic>AtRZF1</italic> was significantly reduced by drought stress. The <italic>atrzf1</italic> mutant was less sensitive to osmotic stress than the wild-type during early seedling development, whereas transgenic plants overexpressing <italic>AtRZF1</italic> were hypersensitive, indicating that AtRZF1 negatively regulates drought-mediated control of early seedling development. Moreover, the ectopic expression of the <italic>AtRZF1</italic> gene was very significantly influential in drought sensitive parameters including proline content, water loss, membrane ion leakage and the expression of dehydration stress-related genes. AtRZF1 is a functional E3 ubiquitin ligase, and its conserved C3H2C3-type RING domain is likely important for the biological function of AtRZF1 in drought response. Together, these results suggest that the E3 ligase AtRZF1 is an important regulator of water deficit stress during early seedling development.

Calcium-dependent Protein Kinase 5 (CPK5) positively modulates drought tolerance through phosphorylating ABA-Responsive Element Binding Factors in oilseed rape (Brassica napus L.)

Drought is an environmental stress that causes severe crop loss. Drought stress can induce abscisic acid (ABA) accumulation and cytoplasmic calcium oscillation. Calcium-dependent protein kinases (CPKs) constitute a group of Ser/Thr protein kinases decoding calcium signals. However, the function and molecular mechanisms of most CPKs in oilseed rape (Brassica napus) remain unknown. Here, we report the functional characterization of BnaCPK5 in drought stress tolerance. BnaCPK5 belongs to Group I of the CPK family and was localized at the plasma membrane and nuclei. Overexpression of BnaCPK5 enhanced drought stress tolerance compared with the control. A screening of interacting proteins identified that BnaCPK5 interacted strongly with two ABA-Responsive Element Binding Factors (ABF/AREBs), BnaABF3 and BnaABF4. BnaCPK5 was shown to phosphorylate both BnaABF3 and BnaABF4 in a kinase assay. Further, it was found that the phosphorylation of BnaABF3 and BnaABF4 by BnaCPK5 increased their transcriptional activities against the famous drought stress marker gene, Responsive to Dehydration (RD) 29B and protein stability. Taken together, these data demonstrate that BnaCPK5 acts as a positive regulator of drought tolerance by, at least in part, phosphorylating two core ABA-signaling components to modulate Late-Embryogenesis Abundant (LEA)-like RD29B expression.