High Temperature Tolerance Research Articles

Improving winter barley adaptation to freezing and heat stresses in the U.S. Midwest: bottlenecks and opportunities

Continental cropping systems are increasingly exposed to extreme and opposing trends of temperatures over the same growing season. This situation is epitomized by winter barley grown in the Upper Midwest, which is subject to temperatures that can be as low as −30 °C during the winter and over 30 °C during summer. This interaction severely limits the potential of this emerging crop, by threatening the winter survival of the crown which is often exposed to lethal freezing stress and by exposing reproductive organs to high temperature (HT) stress, to which this cool-season grass is highly sensitive. This poses a unique challenge that requires the discovery and capture of well-defined sets of traits enabling adaptation to extreme tail ends of a stressor, with limited trade-offs, while minimizing costs. Here, based on a critical literature review, we propose a framework integrating i) environmental characterization (envirotyping), ii) envirotype-relevant scouting of genetic resources, iii) ecophysiology-informed trait identification and phenotyping and iv) breeding pipelines. We outline propositions and guidelines for implementing these steps and discuss their feasibility, with an emphasis on i) identifying novel genetic resources and eco-physiological traits relevant to this problem, ii) navigating their physiological trade-offs and iii) leveraging this information to develop ad hoc phenotyping methods for deployment in breeding programs. Our review indicates that the eco-physiological and genetic bases for improving tolerance to both stresses in the same organism likely exists based on evidence from crop relatives and extremophile species, with smaller vasculature (freezing tolerance) and transpirational cooling (HT tolerance) being prime examples. Our findings indicate that such traits could be captured with minimal trade-offs, and that is possible to use similar phenotyping concepts (thermal imaging) and infrastructure (cold/heat tents) to screen for these traits and accelerate breeding to enhance adaptation to temperature extremes. • Temperature extremes limit winter barley yields grown in the Upper Midwest. • Freezing stress limits crown survival and heat stress limits reproductive development. • A trans-disciplinary framework is proposed to improve adaptation to both stressors. • Physiological/ genetic bases for adaptation to both stresses likely exists. • Possibility to use similar phenotyping infrastructure for promising traits.

Life‐stage‐related desiccation and starvation resistance in the biological control agent Neolema abbreviata

AbstractClimate variability in the tropics is partly associated with reduced and erratic precipitation, heat waves, and cold snaps thereby exerting abiotic environmental stressors to various arthropod species. For herbivorous insects, such extreme weather events may affect host plant quality and availability resulting in additional stressors such as desiccation and starvation. Neolema abbreviata Larcordaire (Coleoptera: Chrysomelidae) is a key biocontrol agent of Tradescantia fluminensis Vell. (Commelinaceae) and has recently been introduced in South Africa for management of its invasive host plant. However, it remains unknown how environmental stressors may influence its performance under anthropogenic climate change. Here, we investigated the effects of desiccation and starvation on performance of N. abbreviata larvae and adults and implications on biological control. Specifically, we measured desiccation and starvation resistance and critical thermal minima (CTmin) and maxima (CTmax) following stress. Desiccation and starvation pre‐treatment reduced both low (CTmin) and high (CTmax) temperature tolerance in both life stages albeit larvae were less cold tolerant and more heat tolerant than adults. In addition, resistance decreased with duration of exposure with desiccation resistance being higher in larvae than in adults, whereas the converse was true for starvation resistance. This indicates the challenges N. abbreviata may encounter when it faces environmental stressors in nature. Therefore, with projected climate change, this may potentially impact on its field establishment, spread, and effectiveness, thereby negatively influencing future classical biocontrol programs. Overall, the results provide valuable information in modelling potential distribution of N. abbreviata and developing sustainable management options of T. fluminensis under rapidly changing environments.

Side-Chain-Type High Dielectric-Constant Dipolar Polyimides with Temperature Resistance.

Innovative dielectric materials with high-temperature resistance and outstanding dielectric properties have attracted tremendous attention in advanced electronical fields. Polyimide(PI) is considered a promising candidate for the modern electronic industry due to its excellent dielectric properties and comprehensive properties. However, the limited-adjustable range of dielectric constant and the difficulty to obtain a high dielectric constant restrict the application of PI as high dielectric materials. Herein, a novel diamine monomer (2,2'-bis((methylsulfonyl)methyl)-[1,1'-biphenyl]-4,4'-diamine (BSBPA)) containing a rigid biphenyl structure and high dipolar sulfonyl pendant groups is designed for high dielectric polyimides. The rigid biphenyl and polar sulfonyl pendant groups can reasonably optimize the molecular structure and orientational polarization of polyimides to improve their dielectric properties and thermal properties. Moreover, the effect of different bridge linkages on the dielectric properties is studied by using the different dianhydrides. Thus, the PI-BSBPA films especially the DSDA-BSBPA film (DSDA: 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride)achieve great thermal properties (T5%d of 377°C and Tg of 358°C) and excellent dielectric properties (6.95 at 1kHz) along with high discharged energy density of 5.25Jcm-3 and charge-discharge efficiency of 90%. The collaborative control of main-chain and side-chain engineering is effective to endow the polyimides with high-temperature tolerance and high dielectric performance.

Enhancing the lithium storage capability of TiO2 thin film for all-solid-state microbatteries via amorphous-crystalline heterostructure design

TiO2 is regarded as a promising anode for all-solid-state thin film lithium-ion microbatteries due to its high temperature tolerance, good chemical stability, and desirable structural stability. However, its application in thin film batteries has been plagued by its low actual capacity and poor rate capability. Herein, a TiO2 thin film with a unique amorphous-crystalline heterostructure (AC-TO) is prepared by magnetron sputtering at room temperature. The heterostructure design of AC-TO not only takes advantage of faster Li+ diffusion of an amorphous phase and higher electric conductivity of a crystalline phase but also reaps the benefit of fast ion transport, fast electron transfer, and additional lithium storage at the hetero-interfaces, resulting in boosted lithium storage performance. When tested in all-solid-state thin film lithium batteries, the AC-TO based device exhibits an obviously higher reversible specific capacity (204 at 50 mA g−1) than the amorphous TiO2 based device (103 mAh g−1) and the crystalline anatase based device (147 mAh g−1), as well as good rate capability (73 at 1600 mA g−1) and excellent cycling stability (nearly no capacity loss after 400 cycles). This work provides an instructive structural regulation strategy for developing advanced thin-film electrodes for all-solid-state microbatteries.

Screening of Rice (Oryza sativa L.) Genotypes for High Temperature Stress under Temperature Induction Response

Plants are exposed to multifarious external environmental conditions that affect plant growth, development and productivity. Heat stress is one of the abiotic stress that occurs due to high ambient temperature. Also, it is a serious threat to crop production worldwide. Rice is a major food crop cultivated all over the globe. In the present study, temperature induction response (TIR) was carried out for screening the rice genotypes. Initially, three rice genotypes namely Swarnamukhi, Kasalth and N22 (tolerant check) were used to standardize the optimum induction temperature and lethal temperature. Optimum induction temperature was 46-54o C and the lethal temperature 56oC were standardized for rice. At this temperature, a total of 58 diverse genotypes were screened for high-temperature stress tolerance. Among the genotypes tried, sivapu chithiraikar (94.33%), kavya (93.67%), kasalath(94.23), samleshwari (93.56), poongar (87.34), vedhividangan (75.10), Naveen (89.56), surakuruvai (84.90), swarnamukhi (92.10), vellaikatrai (80.50) and kavuni (92.60) expressed higher seedling survival percentage of tolerance (93.5%) to high temperature and remaining were identified as temperature susceptible as compared to control (100% survival). There was a considerable variation among the genotypes screened for acquired thermotolerance. Results suggested that TIR is a simple and powerful technique and can be used to screen a large population at the seedling stage to identify thermotolerant lines.

Genotype by Environment Interaction in Rice Under High Temperature Stress Condition in Cagayan

Twelve rice genotypes were planted in four municipalities of Cagayan (Iguig, Peñablanca, Solana, and Tuguegarao). It aimed to assess genotype by environment interaction (GEI) of rice cultivated by farmers in Cagayan as well as their stability. This study was also designed to identify genotypes suited to high temperature-prone areas and the most discriminating environment to screen genotypes for high temperature tolerance. During anthesis, the recorded maximum temperature ranged from 33.6-42.4°C in Iguig, 32.9-44.80C in Peñablanca, 32.1-40.5°C in Solana, and 32.6-41.1°C in Tuguegarao. Panicle and canopy temperature were lower than air temperature in Iguig and Peñablanca but higher in Solana and Tuguegarao. Variance due to genotype, environment and GEI were found significant (p≤0.05) for yield. Environment contributed the greatest proportion to yield which was 43.1% of the total variance, while genotype contributed 35.5%, and GEI 21.5%. Spikelet fertility, panicle length, number of grains per panicle, and grain weight were not significantly affected by GEI. However, panicle length and spikelet fertility were significantly affected by genotype and environment, while number of grains per panicle and grain weight were significantly affected only by environment. NSIC Rc 152, Rc 218, Rc 222, PR40330, and PR42026 were found high-yielding with wide adaptation to high temperature conditions. NSIC Rc 152 and PR40330 were the most outstanding genotypes. These genotypes can be used as parents for development of new heat-tolerant lines. Iguig was the best location for screening and selecting generally adapted genotypes under high temperature condition.

Flexible ferroelectric Pb(Zr0.53Ti0.47)O3 epitaxial films with large radiation and high-temperature tolerance

Radiation and temperature hardness are important for electronic devices operating in harsh environments such as modern medical equipment, outer space, and nuclear energy industries. In this work, we report radiation and temperature-hardened flexible ferroelectric Pb(Zr0.53Ti0.47)O3 epitaxial films that were grown on flexible inorganic mica substrates via van der Waals heteroepitaxy and can be further used for building high-performance electronic devices. We systematically investigated the effect of 60Co-gamma radiation and temperature on the ferroelectric properties of Pb(Zr0.53Ti0.47)O3 films and their flexibility as well. Pb(Zr0.53Ti0.47)O3 films exhibit a radiation and temperature tolerance of up to 20 Mrad and 175 °C, respectively. In particular, the 20 Mrad-irradiated Pb(Zr0.53Ti0.47)O3 film has an excellent retention even after 105 s with extrapolate retention time longer than 10 years and polarization fatigue up to 1010 cycles as well as moderate flexibility and bending stability after bending 105 cycles. Furthermore, we identified that the degradation of macroscopic ferroelectric properties of irradiated Pb(Zr0.53Ti0.47)O3 films originates from the ferroelectric domain pinning effect induced by the ionization effect. Our work demonstrates that flexible ferroelectric Pb(Zr0.53Ti0.47)O3 films are promising for developing novel flexible electronic devices for applications in harsh environments.

Hybridization with Percocypris pingi male can improve the cultivation characteristics of snow trout (Schizothorax wangchiachii), especially the resistance to white spot disease (Ichthyophthirius multifiliis)

Snow trout (Schizothorax) is an important cold-water economic fish in Asian aquaculture, but it has some disadvantages, such as slow growth rate, weak resistance to white spot disease (Ichthyophthirius multifiliis) and high temperature, etc. In contrast, their sister genus, Percocypris, has stronger resistance to white spot disease and high temperature. Distant hybridization can integrate the advantages of both parents, so we attempted to cross S. wangchiachii with P. pingi to obtain F1 hybrids combining the advantages of both parents. Hybridization between P. pingi males and S. wangchiachii females was successful, but backcrossing failed. To explore the cultivation characteristics of hybrid fish, the growth performance, digestive enzyme activity, nutrient composition, gonad development, high temperature tolerance, and white spot disease resistance of hybrid fish and their parents were compared. In growth, a total of 18-week culture experiment (20 °C) were carried out, and the body weight of hybrid fish at 18 weeks (26.13 ± 7.34 g) was significantly higher than that of P. pingi (16.65 ± 6.82 g) and S. wangchiachii (16.05 ± 5.93 g). In digestive enzyme activity, the hybrid fish showed hybrid weakness, but there was no correlation between the digestive enzyme activity and body weight of the hybrid fish and its parents, indicating that the digestive enzyme activity could not reflect the growth differences. In nutritional composition, P. pingi had a higher crude protein content, S. wangchiachii had a higher crude lipid content, and both contents of hybrid fish were closer to those of P. ping. The relative contents of amino acids of the three fishes were similar, while the relative contents of polyunsaturated fatty acids were higher in hybrid fish and P. ping, and their relative content of fishy substances was lower than that of S. wangchiachii. In high temperature tolerance, the mortality temperature of P. ping (33.48 ± 0.39 °C) and hybrid fish (33.00 ± 0.92 °C) was significantly higher than that of S. wangchiachii (31.24 ± 1.07 °C). In tolerance to white spot disease, the hybrid fish showed a significant increase in resistance compared to S. wangchiachii and was almost free of I. multifiliis. In gonad development, the spermatic cells of the pentaploid hybrid fish remained in the spermatocyte stage without spermatozoa, their ovarian cells were lowly differentiated, and these characteristics were sterile phenotypes. In conclusion, hybridization with male P. ping can improve the cultivation characteristics of S. wangchiachi through preliminary research, providing a new perspective and reference for snow trout breeding.

MAPEAMENTO ASSOCIATIVO PARA PRODUTIVIDADE DE GRÃOS EM GERMPLASMA EXÓTICO DE SOJA SOB ALTAS TEMPERATURAS

ABSTRACT Soybeans are among the world’s main crops because they are excellent sources of proteins, micronutrients, and oil. Considering that abiotic stress affects agribusiness, resulting in losses, the grain yield of the crop must be maintained even at high temperatures. In this context, the objective of this study was to select markers related to soybean yield assessed under high temperatures, using associative mapping. The mapping population included 80 soybean PIs and 15 controls. For phenotyping, genotypes were evaluated at high temperatures in an experiment conducted in Teresina (in the state of Piauí) and four characters of interest for agronomy were evaluated: height of the plant when mature, agronomic value, 100-seed weight, and grain yield. Genotyping was carried out using the Affymetrix Platform (180 K Axiom® Soybean Genotyping Array), and the imbalance in the connection between pairs of markers was calculated through the coefficient of determination using the fast permutation test. The analysis of the association between markers and the phenotype of interest was carried out using a generalized linear model approach, including phenotyping data, SNP markers, and information on population structure. The results revealed that 34.06% of loci showed a significant linkage disequilibrium (p < 0.001), and 16 significant associations were found for the four characters related to heat tolerance. These associations can aid breeders that aim to incorporate high temperature tolerance in programs of soybean genetic improvement via selection assisted by markers.

Lipidomics-Assisted GWAS (lGWAS) Approach for Improving High-Temperature Stress Tolerance of Crops.

High-temperature stress (HT) over crop productivity is an important environmental factor demanding more attention as recent global warming trends are alarming and pose a potential threat to crop production. According to the Sixth IPCC report, future years will have longer warm seasons and frequent heat waves. Thus, the need arises to develop HT-tolerant genotypes that can be used to breed high-yielding crops. Several physiological, biochemical, and molecular alterations are orchestrated in providing HT tolerance to a genotype. One mechanism to counter HT is overcoming high-temperature-induced membrane superfluidity and structural disorganizations. Several HT lipidomic studies on different genotypes have indicated the potential involvement of membrane lipid remodelling in providing HT tolerance. Advances in high-throughput analytical techniques such as tandem mass spectrometry have paved the way for large-scale identification and quantification of the enormously diverse lipid molecules in a single run. Physiological trait-based breeding has been employed so far to identify and select HT tolerant genotypes but has several disadvantages, such as the genotype-phenotype gap affecting the efficiency of identifying the underlying genetic association. Tolerant genotypes maintain a high photosynthetic rate, stable membranes, and membrane-associated mechanisms. In this context, studying the HT-induced membrane lipid remodelling, resultant of several up-/down-regulations of genes and post-translational modifications, will aid in identifying potential lipid biomarkers for HT tolerance/susceptibility. The identified lipid biomarkers (LIPIDOTYPE) can thus be considered an intermediate phenotype, bridging the gap between genotype–phenotype (genotype–LIPIDOTYPE–phenotype). Recent works integrating metabolomics with quantitative genetic studies such as GWAS (mGWAS) have provided close associations between genotype, metabolites, and stress-tolerant phenotypes. This review has been sculpted to provide a potential workflow that combines MS-based lipidomics and the robust GWAS (lipidomics assisted GWAS-lGWAS) to identify membrane lipid remodelling related genes and associations which can be used to develop HS tolerant genotypes with enhanced membrane thermostability (MTS) and heat stable photosynthesis (HP).

Whole-genome sequence of a high-temperature edible mushroom Pleurotus giganteus (zhudugu).

Most of the sequenced wood-rotting edible mushroom produce fruiting body at relatively low temperatures. Little information has been known about the high-temperature wood-rotting mushroom. Here, we performed de novo sequencing and assembly of the genome of a high-temperature edible mushroom Pleurotus giganteus from a monokaryotic strain zhudugu2 using the Illumina and Pac-Bio CLR sequencing technologies. P. giganteus, also known as Zhudugu in China, is a well-known culinary edible mushroom that has been widely distributed and cultivated in China, Southeast Asia, and South Asia. The genome consists of 40.00 Mb in 27 contigs with a contig N50 of 4.384 Mb. Phylogenetic analysis reveals that P. giganteus and other strains in Pleurotus clustered in one clade. Phylogenetic analysis and average nucleotide identity analysis indicated that the P. giganteus genome showed a closer relationship with other Pleurotus species. Chromosome collinearity analysis revealed a high level of collinearity between P. ostreatus and P. giganteus. There are 12,628 protein-coding genes annotated in this monoploid genome. A total of 481 enzymes accounting for 514 carbohydrate-active enzymes (CAZymes) terms were identified in the P. giganteus genome, including 15 laccases and 10 class II peroxidases predicted in the genome, which revealed the robustness of lignocellulose degradation capacity of P. giganteus. The mating-A type locus of P. giganteus consisted of a pair of homeodomain mating-type genes HD1 and HD2. The mating-B type locus of P. giganteus consisted of at least four pheromone receptor genes and three pheromone genes. The genome is not only beneficial for the genome-assisted breeding of this mushroom but also helps us to understand the high-temperature tolerance of the edible mushroom.

Evaluation of Plant Growth-Promoting Yeasts and Their Effect on Chickpea Plant Growth

Yeasts play a significant role in a wide range of fields, and the fascination they arouse stems from their incredible diversity in natural habitats. Among these habitats we focused on the soil of a unique biotope (oasis) in the Algerian Sahara, where yeasts have received little attention. For the first time, the distribution of yeasts, was determined depending on the plant and seasons. Their metabolic activity represented in the PGP effects, benefits the studied plant (chickpea) at the soil level involving the production of NH3, IAAs, the solubilization of inorganic phosphorus and zinc oxide, and even the micro-symbionts by the stimulation of nodulation. The isolated yeasts were also shown to possess PGP properties that largely exceed those of the reference strain Saccharomyces cerevisiae, with the strain RSZ1 of Kodamaea ohmeri having the best solubilization and production indices. When compared to the non-infected control and those inoculated with the reference strain S. cerevisiae, these characteristics enhanced the dry biomass yield of the examined plant by three to four or even six times. Another effect was nodulation, in which the number of nodules significantly increased compared to the control. Yeasts have a high-temperature tolerance limit of 43°C, posing a significant challenge in this biotope. This little-known role of yeasts, particularly in Algeria, is interesting, and can be used with other microorganisms as an alternative to hazardous chemical fertilizers and as bio-inputs in the improvement of healthy agricultural production, revegetation of degraded sites, and the establishment of life in these biotopes.

Climatic and biotic influences on the distributions of Calliphora augur and Calliphora dubia (Diptera: Calliphoridae)

AbstractCalliphora augur (Fabricius) and Calliphora dubia (Macquart) are two widespread and endemic Australian blowflies of applied importance. In order to better understand the biology of these species, this study used historical, field and laboratory data to determine and interpret their distributions. Locality records from insect collections and the literature were used to determine the known distributions of each species. The resultant maps were partially verified with field trapping data for each species. Calliphora augur was found to dominate in the east of Australia, while C. dubia dominates in the west. Comparative laboratory and field experiments were also used to derive parameters defining the distributions of these two closely related species, particularly in relation to temperature and moisture. Calliphora dubia had a greater tolerance for dry stress and high temperatures than C. augur, although maggots of both species displayed similar developmental temperature preferences. No difference was seen between species in the impact of low temperatures on the development of maggots through to the pupal stage. The greater ability of C. dubia to tolerate adverse environmental conditions is most likely linked to the shared evolutionary history of both species, in which increased aridity in central Australia is proposed to have triggered speciation by separating ancestral populations: C. dubia evolved in the hot, dry conditions in the west of Australia, while C. augur evolved in the cooler, moist environment of the east. Improved understanding of the influences on the distributions of these common Australian blowflies will assist in the further study of their application to agriculture and forensic science.

Energy-efficient system and charge balancing topology for electric vehicle application

Demand for electric vehicles (EVs) are increased because of flexible, easy to handle, and more powerful energy storage (ES) systems. In electric vehicles, the driving motor would run by energy storage systems. It is necessary to recognize energy storage technologies' battery lifetime, power density, temperature tolerance, and flexible electrochemical behavior. Supercapacitor’s have increased attention due to their exclusive structures such as high capacitance, working efficiency, temperature tolerance, and eco-friendly nature. Additionally, hybrid energy storage systems significantly influence advanced electric vehicles applicable power utilization. A battery management system (BMS) requires a reliable and highly efficient power source from the storage technology for electric vehicles applications. Electrochemical energy storage systems are affected by overcharge/over-discharge, temperature or cell unbalancing. The key factor in a battery management system is cell balancing between cells in a string that prolongs the energy storage device’s lifecycle and performance. This paper highlights a comprehensive study and evaluations focusing on different types of batteries, Supercapacitor’s, and balancing circuits applicable in BMS on electric vehicles and renewable energy storage systems. This rigorous study presents different electrochemical batteries chemistry, anode, cathodes, electrolyte, charging and discharging lifecycle, advantages, and disadvantages. For the Supercapacitor, different types of electrode materials, electrolyte interface, energy storage function, and available Supercapacitor’s capacitance in the market, cell, and module voltage are presented. Also, this study shows the different types of cell balancing circuit’s components number, control complicity, voltage and current stress, overall balancing circuit efficiency, power loss, circuit size and cost, advantages and disadvantages. This manuscript highlights all the insights that will lead to choosing the required and appropriate battery, Supercapacitor or blanching circuit for future applications on electric vehicles systems.

Characterization of Spermidine Synthase (SPDS) Gene and RNA−Seq Based Identification of Spermidine (SPD) and Spermine (SPM) Involvement in Improving High Temperature Stress Tolerance in Gracilariopsis lemaneiformis (Rhodophyta)

Gracilariopsis lemaneiformis, an important commercial red macroalga, is facing significant impacts from global warming, which limits algal growth and yield in China. Polyamines (PAs), spermidine (SPD) and spermine (SPM), are ubiquitous polycations important for growth and environmental stress responses including high temperature (HT) tolerance. Spermidine synthase (SPDS) gene is one of the important genes in higher PA biosynthesis, which plays critical roles in HT stress response. Here, we isolated an SPDS gene from G. lemaneiformis and further analyzed its phylogenetic tree, subcellular localization, and gene expression patterns under stress conditions. Meanwhile, supplemented with SPD and SPM were used to study the effects of PAs on HT tolerance in G. lemaneiformis. It showed exogenous 0.5 mM SPD and SPM, respectively, remarkably improved the algal relative growth rate (RGR) compared to those in the CK treatment groups under HT conditions. In addition, they both significantly elevated the activities of antioxidant enzymes and significantly upregulated the expression of genes encoding antioxidant enzymes, triggered transcription factors (TFs) signaling, and improved the expression of genes encoding small heat shock proteins (sHSP20s) during HT stress. Moreover, exogenous PA also enhanced the expression of genes involved in pyruvate metabolism, ascorbate and aldarate metabolism, and nucleotide excision repair in G. lemaneiformis, which helped to maintain better energy supply, redox homeostasis, and genome integrity under HT stress. Taken together, these data provided valuable information for functional characterization of specific gene in endogenous PA synthesis and uncovered the importance of exogenous PAs in promoting algae adaptation to HT stress.

New tree-level temperature response curves document sensitivity of tree growth to high temperatures across a US-wide climatic gradient.

Temperature is a key climate indicator, whose distribution is expected to shift right in a warming world. However, the high-temperature tolerance of trees is less widely understood than their drought tolerance, especially when it comes to sub-lethal impacts of temperature on tree growth. I use a large data set of annual tree ring widths, combined with a flexible degree day model, to estimate the relationship between temperature and tree radial growth. I find that tree radial growth responds non-linearly to temperature across many ecoregions of the United States: across temperate and/or dry ecoregions, spring-summer temperature increases are beneficial or mostly neutral for tree growth up to around 25-30°C in humid climates and 10-15°C in dry climates, beyond which temperature increases suppress growth. Thirty additional degree days above the optimal temperature breakpoint lead to an average decrease in tree ring width of around 1%-5%, depending on ecoregions, seasons, and inclusion or exclusion of temperature-mediated drought impacts. High temperatures have legacy effects across a 5-year horizon in dry ecoregions, but none in the temperate-humid South-East or among temperature-sensitive trees. I find limited evidence that trees acclimatize to high temperatures within their lifetime: local variation in early exposure to high temperatures, which stems from local variation in the timing of tree birth, does not significantly impact the response to high temperatures, although temperature-sensitive trees acquire some heightened sensitivity from early exposure. I also find some evidence that trees adapt to high temperatures in the long run: across humid ecoregions of the United States, high temperatures are 40% less harmful to tree growth, where their average incidence is one standard deviation above average. Overall, these results highlight the strength of a new methodology which, applied to representative tree ring data, could contribute to predicting forest carbon uptake potential and composition under global change.

How Electrochemical Impedance Spectroscopy Helps Drive Innovation in Fully Hydrocarbon, Reinforced Polymer Electrolyte Membranes

The realm of hydrocarbon-based polymer electrolyte membranes (PEMs) has undergone substantial changes over the past decade. A new era has emerged, based upon strong, fundamental R&D emphasizing both improved performance across a wider range of operating conditions, and greater combined chemical-mechanical stability, when integrated into a state-of-the-art fuel cell. The groundwork has been laid for commercialization of highly promising, fluorine-free technologies which simultaneously outperform previous generation materials, and address weaknesses historically attributed to all hydrocarbon-based membranes. Hydrocarbons address critical issues with perfluorinated sulfonic acid (PFSA) materials. Reduced gas crossover allows longer component lifetimes, operational window for system pressures, and reduced hydrogen venting. Higher temperature tolerances allow system operation or excursions to ≥ 100 °C, which affords a myriad of potential benefits such as reduction in heat exchanger volume, improved system water management, and increased catalyst activity due to mitigated activation losses. Furthermore, higher operating temperatures go hand-in-hand with greater pollution tolerance, and hence reduced hydrogen purity requirements.The award-winning hydrocarbon-based PEM, Pemion®, produced by Ionomr Innovations, is nested at the center of these exciting developments. Mechanically reinforced composite membranes are produced at scale utilizing advanced roll-to-roll manufacturing techniques, affording a hydrocarbon-based PEM that, for the first time, exhibits performance parallel to or greater than incumbent perfluorinated sulfonic acid (PFSA)-based PEMs. These developments, however, would not be possible without powerful characterization methods such as electrochemical impedance spectroscopy (EIS). Assessments of a membrane’s in-plane and through-plane proton conductivity are used to derive valuable insight to its constituents, the ion-conducting ionomer and chemically-inert mechanical reinforcement, as well as their interrelation. The anisotropic nature of the composite membranes is probed via comparison of in-plane and through-plane conductivity. The sensitivity of through-plane conductivity measurements to experimental parameters such as cell pressure are probed, and a new cell design is realized to reduce measurement error. These data help identify favorable and unfavorable material processing and manufacturing techniques, and their implications to in-situ fuel cell performance. The net consequence of these findings is establishing EIS as a core component of an iterative material design and production process for output of consistent, high-performance PEMs.

Overexpression of DfRaf from Fragrant Woodfern (Dryopteris fragrans) Enhances High-Temperature Tolerance in Tobacco (Nicotiana tabacum).

Heat stress seriously affects medicinal herbs’ growth and yield. Rubisco accumulation factor (Raf) is a key mediator regulating the activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), which plays important roles in carbon assimilation and the Calvin cycle in plants. Raf has been studied in many plants, but has rarely been studied in the important medicinal plant fragrant woodfern (Dryopteris fragrans). The aim of this study was to analyze the effects of Raf on carbohydrate metabolism and the response to heat stress in medicinal plants. In this study, high temperature treatment upregulated the expression of DfRaf, which was significantly higher than that of phosphoribokinase (DfPRK), Rubisco small subunits (DfRbcS), Rubisco large subunits (DfRbcL) and Rubisco activase (DfRCA). The subcellular localization showed that the DfRaf proteins were primarily located in the nucleus; DfPRK, DfRbcS, DfRbcL and DfRCA proteins were primarily located in the chloroplast. We found that overexpression of DfRaf led to increased activity of Rubisco, RCA and PRK under high-temperature stress. The H2O2, O2− and MDA content of the DfRaf-OV-L2 and DfRaf-OV-L6 transgenic lines were significantly lower than those of WT and VC plants under high-temperature stress. The photosynthetic pigments, proline, soluble sugar content and ROS-scavenging ability of the DfRaf-OV-L2 and DfRaf-OV-L6 transgenic lines were higher than those of WT and VC plants under high-temperature stress. The results showed that overexpression of the DfRaf gene increased the Rubisco activity, which enhanced the high-temperature tolerance of plants.

Adaptation to environmental temperature in divergent clades of the nematode Pristionchus pacificus.

Because of ongoing climate change, populations of organisms are being subjected to stressful temperatures more often. This is especially problematic for ectothermic organisms, which are likely to be more sensitive to changes in temperature. Therefore, we need to know if ectotherms have adapted to environmental temperature and, if so, what are the evolutionary mechanisms behind such adaptation. Here, we use the nematode Pristionchus pacificus as a case study to investigate thermal adaptation on the Indian Ocean island of La Réunion, which experiences a range of temperatures from coast to summit. We study the evolution of high-temperature tolerance by constructing a phylogenetic tree of strains collected from many different thermal niches. We show that populations of P. pacificus at low altitudes have higher fertility at warmer temperatures. Most likely, this phenotype has arisen recently and at least twice independently, consistent with parallel evolution. We also studied low-temperature tolerance and showed that populations from high altitudes have increased their fertility at cooler temperatures. Together, these data indicate that P. pacificus strains on La Réunion are subject to divergent selection, adapting to hot and cold niches at the coast and summit of the volcano. Precisely defining these thermal niches provides essential information for models that predict the impact of future climate change on these populations.

Expression Regulation Mechanisms of Sea Urchin (Strongylocentrotus intermedius) Under the High Temperature: New Evidence for the miRNA-mRNA Interaction Involvement.

In the context of global warming and continuous high temperatures in the northern part of China during summer, the mortality rate of our main breeding species, Strongylocentrotus intermedius, reached 80% in 2020. How sea urchins respond to high temperatures is of great concern to academia and industry. In this study, we examined the antioxidant enzyme activities of different color tube-footed sea urchins under heat stress and compared their transcriptome and microRNA (miRNA) profiles using RNA-Seq. The results showed that the antioxidant enzyme activities of sea urchins were altered by thermal stress, and the changes in peroxidase activities of red tube-footed sea urchins were particularly significant. Investigations revealed that 1,079 differentially expressed genes (DEGs), 11 DE miRNAs, and 104 “DE miRNA-DEG” pairs in total were detected in sea urchins under high temperature stress. Several mRNA and miRNAs were significantly changed (e.g. HSP70, DnaJ11, HYAL, CALR, miR-184-p5, miR-92a, miR-92c, and miR-124-p5), suggesting these genes and miRNAs exerted important functions in response to high temperature. At the transcriptional level, red tube-footed sea urchins were found to be more sensitive to high temperature and could respond to high temperature rapidly. DE miRNA-mRNA network showed that miR-92b-3p and PC-5p-7420 were the most corresponding miRNAs. Five mRNAs (DnaJ11, SAR1B, CALR, HYOU1, TUBA) may be potential markers of sea urchin response to high temperature. Possible interaction between miRNA-mRNA could be linked to protein folding in the endoplasmic reticulum, Phagosomes, and calcium transport. This study provides a theoretical basis for the molecular mechanism of sea urchin heat tolerance and information that will aid in the selection and breeding of sea urchins with high temperature tolerance.