• 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.
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.
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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.
Climate change is putting the fate of ectothermic animals at stake because their body temperature closely tracks environmental temperatures. The ability to adjust thermal limits and preference ...through acclimation (i.e. acclimation capacity) may compensate for temperature changes. However, although necessary for forecasting the future of ectotherms in a changing climate, knowledge on the factors modulating these plastic responses is fragmentary. For instance, the influence of an animal's sex in driving acclimation capacity has been underappreciated.
Here, we present the first systematic review and meta‐analysis on sex differences in thermal acclimation capacity. Using 239 effect sizes from 37 studies and 44 species, we revealed that males and females did not differ significantly in their overall capacity to acclimate their thermal limits and preference. However, in some instances, females expressed significantly greater plastic responses than males.
In wild animals, females had a greater heat tolerance plasticity than males. In addition, females had a greater cold tolerance plasticity in terrestrial habitats, but the strength and direction of this sexual dimorphism was associated with the duration of acclimation. We also found a negative correlation between body mass and plasticity. Finally, we demonstrated that the capacity for each sex to adjust their thermal tolerance and preference was remarkably limited.
It is important to acknowledge that the above effects were weak and heterogeneous. Hence, in the species we investigated, minor differences in acclimation capacity may not translate into major ecological mismatch between sexes with climate change.
Our systematic review also revealed that over 75% of the studies we identified either did not report or confounded the sex of the animals. This under‐reporting may cause to overlook ecologically relevant sex differences in plasticity in ectothermic taxa. We stress the need for further research on sex‐based responses to temperatures.
Our synthesis provides additional evidence that the capacity for ectotherms to acclimate to temperatures is limited, and likely insufficient to compensate for the impacts of climate change.
A free Plain Language Summary can be found within the Supporting Information of this article.
Résumé
Le changement climatique met en péril le sort des animaux ectothermes car leur température corporelle suit de près les températures environnementales. La capacité de ces animaux à ajuster leurs limites et préférences thermiques (i.e. capacité d'acclimatation) peut éventuellement compenser les changements de température. Cependant, bien que nécessaire pour prévoir l'avenir des ectothermes dans un climat changeant, les connaissances sur les facteurs modulant ces réponses plastiques sont fragmentaires. Notamment, l'influence du sexe d'un animal sur sa capacité d'acclimatation a été sous‐estimée.
Nous présentons ici la première revue systématique et méta‐analyse sur les différences sexuelles en termes de capacité d'acclimatation thermique. En synthétisant 239 points de données provenant de 37 études et 44 espèces, nous avons révélé que mâles et femelles ne diffèrent pas significativement dans leur capacité globale à ajuster leurs préférences et limites thermiques. Cependant, dans certains cas, les femelles expriment une plasticité significativement plus importante que les mâles.
Chez les animaux récemment prélevés de leur milieu naturel, les femelles ont une plus grande capacité à ajuster leur tolérance à la chaleur que les mâles. De plus, la tolérance au froid est plus plastique chez les femelles provenant d'habitats terrestres, bien que l'intensité et la direction du dimorphisme sexuel soient associés avec la durée d'acclimatation. Nous avons également trouvé une négative corrélation entre la masse corporelle et la capacité d'acclimatation. Finalement, nous avons démontré que la capacité d'acclimatation thermique de chaque sexe est extrêmement limitée.
Il est important de reconnaître que les effets ci‐dessus sont faibles et hétérogènes. Par conséquent, chez les espèces que nous avons étudiées, ces mineures différences sexuelles ne produiront probablement pas de conséquences écologiques majeures dans un climat changeant.
Notre revue systématique a également révélé que plus de 75% des études compilées n'indiquaient pas, ou confondaient le sexe des animaux testés. Ce manque d'information peut conduire à une sous‐estimation des différences de plasticité entre mâles et femelles. Nous soulignons la nécessité de poursuivre les recherches sur les réponses aux températures de chaque sexe.
Notre synthèse supporte que la capacité d'acclimatation thermique des ectothermes est limitée, et probablement insuffisante pour compenser les impacts du changement climatique.
A free Plain Language Summary can be found within the Supporting Information of this article.
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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.
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.
Increasing evidence indicates that tolerance is a host defense strategy against pathogens as widespread and successful as resistance. Since the concept of tolerance was proposed more than a century ...ago, it has been in continuous evolution. In parallel, our understanding of its mechanistic bases and its consequences for host and pathogen interactions, ecology, and evolution has grown. This review aims at summarizing the conceptual changes in the meaning of tolerance inside and outside the field of phytopathology, emphasizing difficulties in demonstrating and quantifying this trait. We also discuss evidence of tolerance and current knowledge on its genetic regulation, mechanisms, and role in host-pathogen coevolution, highlighting common patterns across hosts and pathogens. We hope that this comprehensive review attracts more plant pathologists to the study of this key plant defense response.
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.
One application of plant physiological heat tolerance measurements is the assessment of vulnerability to increasing environmental temperatures under climatic change. A thermal safety margin (TSM), ...the difference between physiological tolerance and environmental temperature, is a common metric for the assessment of plant thermal vulnerability. However, there are biological and methodological aspects to consider when evaluating thermal vulnerability that have the potential to substantially alter the assessments. Two such aspects include the leaf to air temperature relationship and the scale at which air temperature data are collected.
We grew plants of a desert species, Myoporum montanum, in situ under water‐stressed and well‐watered conditions, and measured their leaf temperatures and photosynthetic heat tolerance (T50 threshold) every third day over 12 days in summer. Thermal safety margins were calculated based on leaf temperatures and compared to those calculated with local and regional air temperatures.
We found that heat tolerance and the thermal vulnerability assessment of a plant changed with water status. When water was readily available, plants maintained wide leaf temperature safety margins and displayed partial homeothermy. When cooling via transpiration was limited, increasing leaf temperature corresponded with occurrences of leaf poikilo‐ and megathermy, higher heat tolerance and narrower safety margins.
Our study shows high physiological heat thresholds are not necessarily reflective of wide safety margins, but instead can indicate a greater vulnerability and increased risk of heat stress exposure. Calculating TSMs using air temperatures can also substantially alter margin widths. Where possible, the use of leaf temperatures in assessments of thermal vulnerability will lead to more meaningful vulnerability assessments. We recommend considering the source and temporal pairing of temperature measurements as well as plant water status, when measuring and interpreting plant TSMs.
A free Plain Language Summary can be found within the Supporting Information of this article.
A free Plain Language Summary can be found within the Supporting Information of this article.
WRKYs are important regulators in plant development and stress responses. However, knowledge of this superfamily in soybean is limited. In this study, we characterized the drought- and salt-induced ...gene
based on RNA-Seq and qRT-PCR.
, which is 714 bp in length, encoded 237 amino acids and grouped into WRKY II. The promoter region of
included ABER4, MYB, MYC, GT-1, W-box and DPBF
-elements, which possibly participate in abscisic acid (ABA), drought and salt stress responses.
was minimally expressed in different tissues under normal conditions but highly expressed under drought and salt treatments. As a nucleus protein,
was responsive to drought, salt, ABA and salicylic acid (SA) stresses. Using a transgenic hairy root assay, we further characterized the roles of
in abiotic stress tolerance. Compared with control (Williams 82), overexpression of
enhanced drought and salt tolerance, increased proline (Pro) content and decreased malondialdehyde (MDA) content under drought and salt treatment in transgenic soybean seedlings. These results may provide a basis to understand the functions of
in abiotic stress responses in soybean.
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