Previous studies have reported that low temperature (LT) constrains plant growth and restricts productivity in temperate regions. However, the underlying mechanisms are complex and not well ...understood. Over the past ten years, research on the process of adaptation and tolerance of plants during cold stress has been carried out. In molecular terms, researchers prioritize research into the field of the ICE-CBF-COR signaling pathway which is believed to be the important key to the cold acclimation process. Inducer of CBF Expression (
) is a pioneer of cold acclimation and plays a central role in C-repeat binding (CBF) cold induction.
activate the expression of
genes via binding to cis-elements in the promoter of
genes. An ICE-CBF-COR signaling pathway activates the appropriate expression of downstream genes, which encodes osmoregulation substances. In this review, we summarize the recent progress of cold stress tolerance in plants from molecular and physiological perspectives and other factors, such as hormones, light, and circadian clock. Understanding the process of cold stress tolerance and the genes involved in the signaling network for cold stress is essential for improving plants, especially crops.
Soil salinity is one of the major environmental stresses faced by the plants. Sodium chloride is the most important salt responsible for inducing salt stress by disrupting the osmotic potential. Due ...to various innate mechanisms, plants adapt to the sodic niche around them. Genes and transcription factors regulating ion transport and exclusion such as salt overly sensitive (SOS), Na+/H+ exchangers (NHXs), high sodium affinity transporter (HKT) and plasma membrane protein (PMP) are activated during salinity stress and help in alleviating cells of ion toxicity. For salt tolerance in plants signal transduction and gene expression is regulated via transcription factors such as NAM (no apical meristem), ATAF (Arabidopsis transcription activation factor), CUC (cup‐shaped cotyledon), Apetala 2/ethylene responsive factor (AP2/ERF), W‐box binding factor (WRKY) and basic leucine zipper domain (bZIP). Cross‐talk between all these transcription factors and genes aid in developing the tolerance mechanisms adopted by plants against salt stress. These genes and transcription factors regulate the movement of ions out of the cells by opening various membrane ion channels. Mutants or knockouts of all these genes are known to be less salt‐tolerant compared to wild‐types. Using novel molecular techniques such as analysis of genome, transcriptome, ionome and metabolome of a plant, can help in expanding the understanding of salt tolerance mechanism in plants. In this review, we discuss the genes responsible for imparting salt tolerance under salinity stress through transport dynamics of ion balance and need to integrate high‐throughput molecular biology techniques to delineate the issue.
• Soybean (Glycine max) production is severely affected in unfavorable environments. Identification of the regulatory factors conferring stress tolerance would facilitate soybean breeding.
• In this ...study, through coexpression network analysis of salt-tolerant wild soybeans, together with molecular and genetic approaches, we revealed a previously unidentified function of a class B heat shock factor, HSFB2b, in soybean salt stress response.
• We showed that HSFB2b improves salt tolerance through the promotion of flavonoid accumulation by activating one subset of flavonoid biosynthesis-related genes and by inhibiting the repressor gene GmNAC2 to release another subset of genes in the flavonoid biosynthesis pathway. Moreover, four promoter haplotypes of HSFB2b were identified from wild and cultivated soybeans. Promoter haplotype II from salt-tolerant wild soybean Y20, with high promoter activity under salt stress, is probably selected for during domestication. Another promoter haplotype, III, from salt-tolerant wild soybean Y55, had the highest promoter activity under salt stress, had a low distribution frequency and may be subjected to the next wave of selection.
• Together, our results revealed the mechanism of HSFB2b in soybean salt stress tolerance. Its promoter variations were identified, and the haplotype with high activity may be adopted for breeding better soybean cultivars that are adapted to stress conditions.
Abstract Understanding the drivers of variation in thermal ecophysiology is essential for characterizing the risks to plant communities posed by the increasing frequencies and intensities of heat ...waves predicted with climate warming. We evaluated the effects of estuarine salinity and short‐term leaf dehydration on photosynthetic (PSII) heat tolerance ( P HT ). In the leaves of 12 mangrove species sampled at contrasting salinities along a 20 km estuarine salinity gradient, we measured minimum chlorophyll fluorescence ( F 0 ) with increasing leaf temperature to determine T crit (the temperature beyond which PSII is destabilized and F 0 rises rapidly) and T max (the temperature where F 0 declines rapidly with catastrophic cell membrane failure). Furthermore, to assess the impacts of leaf dehydration on P HT over short time scales, we re‐measured leaves following a bench‐drying dehydration treatment. T crit was ~2.51°C higher in leaves of high‐salinity‐distributed mangrove species, increasing by ~0.74°C per practical salinity unit (PSU, ppt) along the estuarine salinity gradient. T max was ~1.1°C higher in high‐salinity‐distributed species, increasing by ~0.38°C ppt −1 . Following dehydration, T crit increased by ~3.4°C in low‐salinity‐distributed species; however, no increase in T crit was observed in high‐salinity‐distributed species. Following dehydration, T max increased by ~1.8°C in both low and high‐salinity‐distributed mangrove species. Our results illustrate that spatial gradients in salinity, and the variation in growth environments they produce, are associated with gradients in P HT across mangrove species differing in salinity tolerance and within species with broad salinity tolerances. Further, we show that variation in leaf hydration over short time scales influences P HT , with leaf dehydration improving the heat tolerance of PSII. Combined, these results highlight that both tissue and environmental water availability gradients may produce cross‐tolerance in PSII, that is, increasing stability at high temperatures. Our results underscore the need for greater resolution of the interactive effects of plant water relations, hydration status and photosynthetic thermal safety across biomes and in a warming world. Read the free Plain Language Summary for this article on the Journal blog.
Hexaploid bread wheat (Triticum aestivum L., genome BBAADD) is generally more salt tolerant than its tetraploid wheat progenitor (Triticum turgidum L.). However, little is known about the ...physiological basis of this trait or about the relative contributions of allohexaploidization and subsequent evolutionary genetic changes on the trait development. Here, we compared the salt tolerance of a synthetic allohexaploid wheat (neo-6 x) with its tetraploid (T. turgidum ; BBAA) and diploid (Aegilops tauschii; DD) parents, as well as a natural hexaploid bread wheat (nat-6 x). We studied 92 morphophysiological traits and analyzed homeologous gene expression of a major salt-tolerance gene High-Affinity K ⁺ Transporter 1;5 (HKT1;5). We observed that under salt stress, neo-6 x exhibited higher fitness than both of its parental genotypes due to inheritance of favorable traits like higher germination rate from the 4 x parent and the stronger root Na ⁺ retention capacity from the 2 x parent. Moreover, expression of the D-subgenome HKT1;5 homeolog, which is responsible for Na ⁺ removal from the xylem vessels, showed an immediate transcriptional reprogramming following allohexaploidization, i.e., from constitutive high basal expression in Ae. tauschii (2 x) to salt-induced expression in neo-6 x . This phenomenon was also witnessed in the nat-6 x . An integrated analysis of 92 traits showed that, under salt-stress conditions, neo-6 x resembled more closely the 2 x than the 4 x parent, suggesting that the salt stress induces enhanced expressivity of the D-subgenome homeologs in the synthetic hexaploid wheat. Collectively, the results suggest that condition-dependent functionalization of the subgenomes might have contributed to the wide-ranging adaptability of natural hexaploid wheat.
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•Sulfation forms SO42− and increases NH3 adsorptivity.•PS-NCLS sample forms new Brönsted acid sites. It shows excellent SCR activity and tolerance to H2O and SO2.•The reaction process ...upon PS-NCLS sample follows L–H mechanism.•A shrinking core model was proposed to explain sulfation process.
Ceria-based catalysts exhibit excellent performance at mediate-high temperature in selective catalytic reduction (SCR) of NO with NH3. However, their activities are severely restrained in the presence of H2O and SO2. In this work, Ni–Ce–La composite oxide nanocrystals were synthesized. After sulfation, it showed excellent H2O and SO2 tolerance. The catalysts were studied by inductively coupled plasma (ICP), energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), temperature-programmed desorption (TPD), in situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS), Brunauer–Emmett–Teller (BET) surface area and thermogravimetry (TG). The H2O and SO2 tolerance of Ce-based catalysts and sulfation mechanism and its effect on the SCR activity were investigated. After sulfation, the increase in proportion of Ce3+/(Ce3++Ce4+), the formation of SO42− and the increase of NH3 adsorptivity all illustrate that sulfation increases the Brönsted acid sites of samples. The mainly reserved Lewis acid sites and the newly formed Brönsted acid sites contribute to the excellent SCR activity. A shrinking core model was proposed to explain the process of sulfation. The reaction process mostly follows L–H mechanism. After sulfation, Ni–Ce–La composite oxide increases NH3 adsorptivity and remains good NO adsorptivity, which greatly enhances resistance to H2O and SO2.
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•Sm-doping strengthened NH3-SCR activity and SO2 tolerance over MnFeOx catalyst.•Enhanced NO2 cooperated with increased NH3 (ads) to cause “Fast SCR” reaction.•Sm induced Fe serving ...as sacrificial sites to preferentially react with SO2.•Mechanism model for improving activity and SO2 tolerance with Sm was proposed.
The development of catalysts with high NH3-SCR activity in the presence of SO2 was urgent for non-electric industries to control NOx emission at low temperature. Herein, a series of Sm-doping MnFeOx catalysts were synthesized through a typical PEG-assisted co-precipitation method and applied for low-temperature NH3-SCR process. SmMnFe-0.1 catalyst significantly broadened the activation temperature window and yielded almost 100% NO conversion from 75 to 200 °C, simultaneously, the NO removal efficiency still maintained at about 90% in the presence of SO2 and H2O. The characterization results confirmed that Sm could optimize the dispersity of active components and enlarge the surface area of catalyst. Furthermore, strong interaction among active ions facilitated more oxygen vacancies and accelerated NO oxidizing to NO2, further cooperating with abundant adsorbed NH3, leading to cause “Fast SCR” reaction. Both catalysts were dominated by the E-R mechanism despite MnFeOx catalyst also obeyed the L-H pathway. Particularly, the intense redox circles between Sm and Mn inhibited the electron transferring from SO2 to Mn ions, and induced Fe species serving as sacrificial sites along with Sm to preferentially react with SO2, resulting in an excellent SO2 tolerance, and the possible mechanism model was proposed.
Host defense mechanisms are categorized into different strategies, namely, avoidance, resistance and tolerance. Resistance encompasses mechanisms that directly kill the pathogen while tolerance is ...mainly concerned with alleviating the harsh consequences of the infection regardless of the pathogen burden. Resistance is well‐known strategy in immunology while tolerance is relatively new. Studies addressed tolerance mainly using mouse models revealing a wide range of interesting tolerance mechanisms. Herein, we aim to emphasize on the interspecies comparative approaches to explore potential new mechanisms of disease tolerance. We will discuss mechanisms of tolerance with focus on those that were revealed using comparative study designs of mammals followed by summarizing the reasons for adopting comparative approaches on disease tolerance studies. Disease tolerance is a relatively new concept in immunology, we believe combining comparative studies with model organism study designs will enhance our understanding to tolerance and unveil new mechanisms of tolerance.
Disease tolerance is one of the major immune strategies that recently gained considerable attention in immunology. In this review, we aim to emphasize on the comparative approaches, beside mouse model studies, to uncover potential tolerance mechanisms that results from unique adaptation of animals especially mammals to diverse environments.
Because of the rise in global temperature, heat stress has become a major concern for crop production. Heat stress deteriorates plant productivity and alters phenological and physiological responses ...that aid in precise monitoring and sensing of mild-to-severe transient heat stress. Plants have evolved several sophisticated mechanisms including hormone-signaling pathways to sense heat stimuli and acquire heat stress tolerance. In response to heat stress, ethylene, a gaseous hormone, is produced which is indispensable for plant growth and development and tolerance to various abiotic stresses including heat stress. The manipulation of ethylene in developing heat stress tolerance targeting ethylene biosynthesis and signaling pathways has brought promising out comes. Conversely increased ethylene biosynthesis and signaling seem to exhibit inhibitory effects in plant growth responses from primitive to maturity stages. This review mainly focuses on the recent studies of ethylene involvement in plant responses to heat stress and its functional regulation, and molecular mechanism underlying the plant responses in the mitigation of heat-induced damages. Furthermore, this review also describes the crosstalk between ethylene and other signaling molecules under heat stress and approaches to improve heat stress tolerance in plants.
Insulin resistance (IR) is predictive for type 2 diabetes and associated with various metabolic abnormalities in fasting conditions. However, limited data are available on how IR affects metabolic ...responses in a non-fasting setting, yet this is the state people are mostly exposed to during waking hours in the modern society. Here, we aim to comprehensively characterise the metabolic changes in response to an oral glucose test (OGTT) and assess the associations of these changes with IR.
Blood samples were obtained at 0 (fasting baseline, right before glucose ingestion), 30, 60, and 120 min during the OGTT. Seventy-eight metabolic measures were analysed at each time point for a discovery cohort of 4745 middle-aged Finnish individuals and a replication cohort of 595 senior Finnish participants. We assessed the metabolic changes in response to glucose ingestion (percentage change in relative to fasting baseline) across the four time points and further compared the response profile between five groups with different levels of IR and glucose intolerance. Further, the differences were tested for covariate adjustment, including gender, body mass index, systolic blood pressure, fasting, and 2-h glucose levels. The groups were defined as insulin sensitive with normal glucose (IS-NGT), insulin resistant with normal glucose (IR-NGT), impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and new diabetes (NDM). IS-NGT and IR-NGT were defined as the first and fourth quartile of fasting insulin in NGT individuals.
Glucose ingestion induced multiple metabolic responses, including increased glycolysis intermediates and decreased branched-chain amino acids, ketone bodies, glycerol, and triglycerides. The IR-NGT subgroup showed smaller responses for these measures (mean + 23%, interquartile 9-34% at 120 min) compared to IS-NGT (34%, 23-44%, P < 0.0006 for difference, corrected for multiple testing). Notably, the three groups with glucose abnormality (IFG, IGT, and NDM) showed similar metabolic dysregulations as those of IR-NGT. The difference between the IS-NGT and the other subgroups was largely explained by fasting insulin, but not fasting or 2 h glucose. The findings were consistent after covariate adjustment and between the discovery and replication cohort.
Insulin-resistant non-diabetic individuals are exposed to a similar adverse postprandial metabolic milieu, and analogous cardiometabolic risk, as those with type 2 diabetes. The wide range of metabolic abnormalities associated with IR highlights the necessity of diabetes diagnostics and clinical care beyond glucose management.
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