High Temperature Stress Research Articles

SIRT2-mediated deacetylation of glutathione transferase alleviates oxidative damage and increases the heat tolerance of Pleurotus ostreatus

High-temperature stress (HS) severely threatens agricultural production. Pleurotus ostreatus is cultivated in many parts of the world, and its growth is strongly affected by HS. We previously reported that metabolic rearrangement occurred in HS, but the gene expression levels of several key enzymes remained unchanged. Therefore, in this study, we investigated the contribution of posttranslational modifications of proteins to HS resistance in P. ostreatus. We found that the level of acetylation of P. ostreatus decreased under short-term HS treatment and increased as the duration of HS treatment increased. Acetylation omics revealed that almost all metabolic enzymes were acetylated. We found that deacetylation under HS can improve the growth recovery ability of mycelia, the activity of matrix-degrading enzyme, and the contents of antioxidants, such as nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione (GSH), but can decreased H2O2 levels. In vitro acetylation experiments and point mutations revealed that the deacetylase SIRT2 increased the activity of glutathione transferases (GSTs) by deacetylating GST1 66K, GST2 206K, and GST2 233K. Together, SIRT2 is activated by short-term HS and improves its antioxidant activity by deacetylating GSTs, thereby improving the resistance of P. ostreatus to HS. In this study, we identified new non-histone substrate proteins and new lysine acetylation sites of SIRT2 under HS. We also discovered the role of non-histone acetylation in the adaptation of organisms to HS.

Rapid and high-throughput identification of thermal-responsive genes based on cDNA-library in Upland Cotton

Severe high temperature (HT) climate significantly impacts cotton quality and yield. Consequently, it is essential to mine thermal-responsive genes and explore the underlying mechanisms of HT response in cotton. In this study, we employed a high-throughput cDNA-library method in conjunction with the ALRS system to screen thermotolerant genes in Upland cotton. As a result, a total of 16,120, 13,216 and 172 effective survival genes were filtered after HT stress exposure (42 °C, 220 rpm) for 48 h, 60 h and 72 h, respectively. Functional annotation and enrichment analysis revealed that 170 common genes were involved in regulatory processes associated with HT stress, and the relevant transcriptome data indicated that the majority of these genes responded to temperature fluctuations. Twenty-one genes were randomly selected for verification, and it was found that these genes could enhance yeast resistance to HT stress. Additionally, we selected mutants of homologous Arabidopsis genes for four candidate genes to validate plant thermotolerance during flowering; the thermotolerances of SALK_201915 and SALK_120540.1 were significantly worse. The results demonstrate that numerous candidate genes identified from the cDNA-library contribute to the highly complex molecular network that governs the response and resistance to HT stress in Upland cotton. The high-throughput heat-screening method utilized in this study was optimized for mining thermotolerant genes including improvement in yeast library construction, screening system, gradient reverse pressure, and sequencing library construction. We hope that this new method can be applied in future studies on stress in cotton and other species.

Tobacco production under global climate change: combined effects of heat and drought stress and coping strategies

With the intensification of global climate change, high-temperature and drought stress have emerged as critical environmental stressors affecting tobacco plants’ growth, development, and yield. This study provides a comprehensive review of tobacco’s physiological and biochemical responses to optimal temperature conditions and limited irrigation across various growth stages. It assesses the effects of these conditions on yield and quality, along with the synergistic interactions and molecular mechanisms associated with these stressors. High-temperature and drought stress induces alterations in both enzymatic and non-enzymatic antioxidant activities, lead to the accumulation of reactive oxygen species (ROS), and promote lipid peroxidation, all of which adversely impact physiological processes such as photosynthetic gas exchange, respiration, and nitrogen metabolism, ultimately resulting in reduced biomass, productivity, and quality. The interaction of these stressors activates novel plant defense mechanisms, contributing to exacerbated synergistic damage. Optimal temperature conditions enhance the activation of heat shock proteins (HSPs) and antioxidant-related genes at the molecular level. At the same time, water stress triggers the expression of genes regulated by both abscisic acid-dependent and independent signaling pathways. This review also discusses contemporary agricultural management strategies, applications of genetic engineering, and biotechnological and molecular breeding methods designed to mitigate adverse agroclimatic responses, focusing on enhancing tobacco production under heat and drought stress conditions.

An Integrative Analysis of the Transcriptome and Proteome of Rice Grain Chalkiness Formation Under High Temperature

Exposure to high temperatures can impair the grain-filling process in rice (Oryza sativa L.), potentially leading to the formation of chalky endosperm, but the molecular regulation mechanism remains largely elusive. Here, we reported that high-temperature (HT) stress (day/night, 35 °C/30 °C) reduces both the grain-filling rate and grain weight of Ningjing 1 variety compared to normal temperatures (NT, day/night, 28 °C/23 °C). Grains under HT stress exhibited an opaque, milky-white appearance, alongside significant alterations in starch physicochemical properties. An integrated transcriptomic analysis of grains under HT revealed up-regulation of genes related to defense mechanisms and oxidoreductase activity, while genes involved in sucrose and starch synthesis were down-regulated, and α-amylase genes were up-regulated. Proteomic analysis of grains under HT echoed this pattern. These results demonstrate that high temperature during the grain-filling stage significantly increases rice chalkiness by down-regulating genes related to sucrose and starch synthesis, while up-regulating those involved in starch degradation.

An integrated physiological indicator and transcriptomic analysis reveals the response of soybean buds to high-temperature stress.

Under global warming, high temperature (HT) has become a major meteorological factor affecting soybean production. To explore the candidate genes and regulatory mechanism of the soybean bud response to HT stress, previously identified as HT-tolerant ('Handou14'; HD14) and HT-sensitive ('Jiadou36'; JD36) were treated for 5 days in an artificial climate incubator either with HT (43°C (day)/ 33°C (night), 16h light/8h darkness) or the non-stress growth condition (25°C, 16h light/8h darkness) as the control at the bud stage were used as experimental materials in this study. After HT treatment, changes in physiological indicators including hypocotyl length, enzyme activity and hormone content were detected; at the same time, the cotyledons, hypocotyls, and main roots were collected for transcriptome sequencing analysis. Analyzing the mechanisms of HT stress response in the bud stage of HD14 and JD36 at physiological and transcription levels. Analysis of physiological indicator showed that the activities of superoxide dismutase (SOD) were significantly increased 47.4% and 41.2% in the cotyledon of HD14 and the main root of JD36, and the contents of peroxidase (POD) were significantly increased 61.5% and 125% in the hypocotyl of HD14 and JD36; the contents of malonaldehyde (MDA) were significantly increased 44.8% and 22.2% in the main root of HD14 and JD36 after HT treatment. The content of abscisic acid (ABA) were significantly increased 1.9 fold and 1.2 fold in the root of HD14 and JD36 in response to HT treatment, whereas the content of gibberellin (GA) were decreased 2.2 fold and 1.3 fold in the cotyledon and root, and increased 1.6 fold in the hypocotyl in HD14 (P < 0.05). Thus, higher SOD and POD activities, higher ABA content, and a smaller increase in MDA content may improve tolerance to HT stress. The HT-tolerant cultivar may have stronger GA signal transduction in the hypocotyl to combat the negative effects of HT. RNA-sequencing was performed to analyze the differential expression of genes in buds of the two cultivars under the HT treatment and control condition. In total, 3,633, 1,964, 9,934, and 3,036 differentially expressed genes (DEGs) were identified in the CH (control group of HD14) vs. TH (HT-treatment group of HD14), CJ (control group of JD36) vs. TJ (HT-treatment group of JD36), TJ vs. TH, and CJ vs. CH comparison groups, respectively. Bioinformatic analysis revealed that most DEGs were mainly involved in metabolic processes, catalytic activity, carbohydrate, energy transduction, and signaling pathways. The results of qRT-PCR validation (86.67%) and changes in physiological indicators were consistent with the RNA-sequencing data. Five DEGs were selected as candidate genes in the response to HT stress at the bud stage. In summary, soybean cells are protected from oxidative damage by an increase in antioxidant enzyme activities and accumulation of hormone content under HT stress. Concomitantly, changes in the expression of crucial genes and signal transmission processes are induced, thus initiating adaptive and protective mechanisms. This study provides a theoretical basis for clarification of the physiological and molecular mechanisms in the response to HT stress of soybean bud.

Influence of seed-applied biostimulants on soybean germination and early seedling growth under low and high temperature stress

AbstractBiostimulants are environment-friendly agricultural inputs that can improve plant health and yield potential under environmental stressors. Soybeans subjected to extreme temperatures during the growing seasons impacts plant health and performance. Uniform emergence and vigorous seedling establishment are the two traits during the early season that directly correlate with the final yield and are sensitive to abiotic stress. This study tested the effectiveness of seed-applied biostimulants in improving seed germination and emergence traits under different temperatures, low (15 °C, LT), optimum (25 °C, OT), and high (35 °C, HT), using three phenotyping methods such as the paper roll, growth pouch, and soil-based pot culture. Germination, emergence, and seedling growth were significantly accelerated under OT and HT compared to LT in both biostimulant-treated and untreated seeds. While seeds treated with biostimulants exhibited minor differences in germination, emergence, and growth traits under LT and HT compared to the OT. In the soil-based pot culture experiment, humic and fulvic acid-containing treatments extended the time to 50% emergence under LT. This delay was associated with a 13% increase in seedling biomass. A bacillus containing biostimulant improved seedling vigor by 7% under LT compared to untreated check. Notably, biostimulants containing bacterial strains, fulvic acid, and humic acid were found to have a role in reducing time to germination or emergence and enhancing seedling growth. However, the results obtained from different phenotyping methods were inconsistent, suggesting that the effects of biostimulants on germination and growth parameters may be more targeted rather than broad-spectrum. Future research is necessary to optimize application rates and fully explore their potential to mitigate the effects of stressors during the growing season.

Variation in reproductive organ functionality among a population of tomato genotypes reveals the importance of pollen viability and fruit set in response to heat stress

ABSTRACT High temperature limit crop productivity as a consequence of global warming and climate change. In particular, high temperature interferes with sexual reproduction and thus fruit and seed formation in crops. In the present study, phenotypic evaluation of a tomato population, including 21 tomato genotypes, was carried out under high-temperature stress (35°C). Several reproductive and yield-related traits, including the number of inflorescences, number of flowers per inflorescence, pollen viability, fruit set, number of fruits per plant, and number of fruits per inflorescence, were investigated. Significant positive correlations between pollen viability and fruit set were observed (r = 0.83). Based on the obtained findings, the fruit set, pollen viability, number of fruits per plant, and number of fruits per inflorescence were recognized as markers for heat tolerance screening of tomato genotypes. These traits effectively separate tolerant and sensitive genotypes, which can be used in breeding program. At the same time, the number of inflorescences and the number of flowers per inflorescence did not separate between tolerant and sensitive genotypes. In conclusion, heat stress, through influencing pollen viability and fertilization, imposes its effects on reproductive organ development in tomato genotypes.

Evaluation of Five Asian Lily Cultivars in Chongqing Province China and Effects of Exogenous Substances on the Heat Resistance

Lily is one of the world’s important ornamental flowers. Potted Asiatic lily is a further selected dwarf cultivar suitable for indoor or garden planting. However, there is a lack of relevant research on the cultivation adaptability of potted Asiatic lilies cultivars in the Chongqing region which in the southwest of China. This study selected five potted Asiatic lily cultivars, and the phenological period, stem and leaf characteristics, and flowering traits were assessed through statistical observation. The Asiatic lily ‘Tiny Ghost’ and ‘Tiny Double You’ are well-suited for both spring and autumn planting in Chongqing, while ‘Sugar Love’ and ‘Curitiba’ are best planted in the spring. The ‘Tiny Diamond’ is more appropriate for autumn planting due to its low tolerance to high temperature. The application of exogenous substances, including calcium chloride (CaCl2), potassium fulvic acid (PFA) and melatonin (MT), can mitigate the detrimental effects of high-temperature stress on ‘Tiny Diamond’ by regulating photosynthesis, antioxidant systems, and osmotic substance content. A comprehensive evaluation using the membership function showed that the effect of exogenous CaCl2 treatment is the best, followed by exogenous PFA treatment. CaCl2 acts as a positive regulator of heat stress tolerance in Asian lilies, with potential applications in Asian lily cultivation. This study provides reference for cultivation and application of Asian lily varieties in Chongqing region, and also laid the foundation for further research on the mechanism of exogenous substances alleviating heat stress in lilies.

Physiological and Transcriptome Analyses Provide Insights into the Response of Grain Filling to High Temperature in Male-Sterile Wheat (Triticum aestivum L.) Lines.

High-temperature (HT) stress frequently affects the early and middle stages of grain filling in hybrid seed production regions. Photo-thermo-sensitive male-sterile (PTMS) wheat lines, which play a critical role as female parents in hybrid seed production, face challenges under HT conditions. However, the mechanisms governing grain filling in PTMS lines under HT stress remain poorly understood. This study used the BS253 line to investigate the effects of HT on grain filling, primarily focusing on the transition from sucrose unloading to starch synthesis. The findings indicated that HT significantly reduced the grain starch content and weight by 7.65% and 36.35% at maturity, respectively. Further analysis revealed that the expression levels of TaSUT1 and TaSWEETs in grains initially increased after HT stress, paralleling the rise in sucrose content during the same period. The activities of ADP-glucose pyrophosphorylase, UDP-glucose pyrophosphorylase, granule-bound starch synthase, and soluble starch synthase were markedly decreased, indicating that impaired starch synthesis was a key factor limiting grain filling immediately after HT exposure. A total of 41 key regulatory genes involved in sucrose-to-starch metabolism were identified, with HT significantly reducing the expression of genes associated with pathways from sucrose unloading to starch synthesis during the middle and late stages post-HT. Based on the observed ultrastructural changes in the abdominal phloem and sucrose transporter expression levels under HT, we concluded that limited sucrose supply, degradation, and inhibition of starch synthesis collectively constrained grain filling during these stages. Additionally, 11 heat shock proteins and two catalase genes were identified and significantly upregulated during the initial phase post-HT, suggesting their potential role in enhancing sucrose supply at this critical time. More importantly, seven key genes involved in the sucrose-to-starch pathway were identified by weighted gene co-expression network analysis (WGCNA), which provides target genes for their functional research for starch synthase. These findings provide a comprehensive understanding of how HT limits grain filling, identify several genes involved in the sucrose-to-starch pathway, and offer a novel perspective for future research on HT-restricted grain filling across the entire process from sucrose unloading to starch synthesis in developing grains.

VvFHY3 links auxin and endoplasmic reticulum stress to regulate grape anthocyanin biosynthesis at high temperatures.

Anthocyanins affect quality in fruits such as grape (Vitis vinifera). High temperatures reduce anthocyanin levels by suppressing the expression of anthocyanin biosynthesis genes and decreasing the biosynthetic rate. However, the regulatory mechanisms that coordinate these two processes remain largely unknown. In this study, we demonstrate that high-temperature-mediated inhibition of anthocyanin biosynthesis in grape berries depends on the auxin and endoplasmic reticulum (ER) stress pathways. Inactivation of these pathways restores anthocyanin accumulation under high temperatures. We identified and characterized FAR-RED ELONGATED HYPOCOTYL3 (FHY3), a high-temperature-modulated transcription factor that activates multiple anthocyanin biosynthesis genes by binding to their promoters. The auxin response factor VvARF3 interacts with VvFHY3 and represses its transactivation activity, antagonizing VvFHY3-induced anthocyanin biosynthesis. Additionally, we found that the ER stress sensor VvbZIP17 represses anthocyanin biosynthesis. VvFHY3 suppresses VvbZIP17 activity by directly binding to the VvbZIP17 promoter to repress its transcription and by physically interacting with VvbZIP17 to block its DNA binding ability. Furthermore, AUXIN RESPONSE FACTOR 3 (ARF3) interferes with the VvFHY3-VvbZIP17 interaction, releasing VvbZIP17 to activate the unfolded protein response and further suppress anthocyanin production. Our results unravel the VvARF3-VvFHY3-VvbZIP17 regulatory module, which links the auxin and ER stress pathways to coordinately repress anthocyanin structural gene expression and biosynthesis under high-temperature stress.

Integration of mRNA and miRNA Analysis Sheds New Light on the Muscle Response to Heat Stress in Spotted Sea Bass (Lateolabrax maculatus).

Temperature is a crucial environmental factor for fish. Elevated temperatures trigger various physiological and molecular responses designed to maintain internal environmental homeostasis and ensure the proper functioning of the organism. In this study, we measured biochemical parameters and performed mRNA-miRNA integrated transcriptomic analysis to characterize changes in gene expression profiles in the muscle tissue of spotted sea bass (Lateolabrax maculatus) under heat stress. The measurement of biochemical parameters revealed that the activities of nine biochemical enzymes (ALP, γ-GT, AST, GLU, CK, ALT, TG, LDH and TC) were significantly affected to varying degrees by elevated temperatures. A total of 1940 overlapping differentially expressed genes (DEGs) were identified among the five comparisons in the muscle tissue after heat stress. Protein-protein interaction (PPI) analysis of DEGs indicated that heat shock protein genes (HSPs) were deeply involved in the response to heat stress. In addition, we detected 462 differential alternative splicing (DAS) events and 618 DAS genes, which are closely associated with sarcomere assembly in muscle, highlighting the role of alternative splicing in thermal response regulation. Moreover, 32 differentially expressed miRNAs (DEMs) were identified in response to heat stress, and 599 DEGs were predicted as potential target genes of those DEMs, generating 846 DEG-DEM negative regulatory pairs potentially associated with thermal response. Function enrichment analysis of the target genes suggested that lipid metabolism-related pathways and genes were regulated by miRNAs. By analyzing PPIs of target genes, we identified 28 key negative regulatory pairs, including 13 miRNAs (such as lma-miR-122, lma-miR-200b-5p and novel-miR-444) and 15 target genes (such as hspa13, dnaja1, and dnajb1a). This study elucidates the molecular mechanisms of response to high-temperature stress and offers valuable information for the selection and breeding of heat-tolerant strains of spotted sea bass.

Organ-Spesific Gene Expression Profiles of Bread Wheat (Triticum aestivum L.) in Response to Combined Abiotic Stress Factors

Bread wheat (Triticum aestivum L.) is used widely as human food in the world, in our country also, is a plant with an important place in terms of economy, food and trade. New-generation sequencing technology is a significant tool that provides information about the transcriptome profile and dynamics of cells and tissues. This study investigated the regulation of gene expression in root, leaf, and grain tissues of bread wheat in response to drought and/or heat stress at the grain-filling stage for the first time by the transcriptome analysis. The sequencing result, obtained on a Roche 454 GS FLX+, yielded a total of 117,790,028 base reads and 8,351 unigenes with an average length of 461 bp. Through transcriptome analysis, numerous transcripts have been identified to be involved in maintaining osmotic and ionic balance, detecting and transmitting signals, modifying protein structure and function, ensuring membrane integrity and stability, and are associated with energy and carbohydrate metabolism. Against drought and high temperature stresses, tolerance mechanisms in the root, leaf, and grain tissues differentially regulated many specific transcription factors identified. Betaine aldehyde dehydrogenase, callose synthase, cell wall-associated hydrolase, MYB33, NAC69 transcription factors expression levels were measured with qRT-PCR. Transcriptome analysis revealed that the transcripts identified were related to osmotic and ionic balance, signal detection and transduction, modification of structural and functional proteins, cell membrane structure and stability, energy and carbohydrate metabolism, and their expression level varied according to the tissue or drought and high temperature stress applied.

High temperature stress induced changes in physiological, biochemical, hormonal and gene expression patterns in contrasting tomato genotypes

High temperature stress induced changes in physiological, biochemical, hormonal and gene expression patterns in contrasting tomato genotypes

TORC1 Regulates Thermotolerance via Modulating Metabolic Rate and Antioxidant Capacity in Scallop Argopecten irradians irradians.

Target of rapamycin complex 1 (TORC1) is a key regulator of metabolism in eukaryotes across multiple pathways. Although TORC1 has been extensively studied in vertebrates and some invertebrates, research on this complex in scallops is limited. In this study, we identified the genes encoding TORC1 complex subunits in the scallop Argopecten irradians irradians through genome-wide in silico scanning. Five genes, including TOR, RAPTOR, LST8, DEPTOR, and PRAS40, that encode the subunits of TORC1 complex were identified in the bay scallop. We then conducted structural characterization and phylogenetic analysis of the A. i. irradians TORC1 (AiTORC1) subunits to determine their structural features and evolutionary relationships. Next, we analyzed the spatiotemporal expressions of AiTORC1-coding genes during various embryo/larvae developmental stages and across different tissues in healthy adult scallops. The results revealed stage- and tissue-specific expression patterns, suggesting diverse roles in development and growth. Furthermore, the regulation of AiTORC1-coding genes was examined in temperature-sensitive tissues (the mantle, gill, hemocyte, and heart) of bay scallops exposed to high-temperature (32 °C) stress over different durations (0 h, 6 h, 12 h, 24 h, 3 d, 6 d, and 10 d). The expression of AiTORC1-coding genes was predominantly suppressed in the hemocyte but was generally activated in the mantle, gill, and heart, indicating a tissue-specific response to heat stress. Finally, functional validation was performed using the TOR inhibitor rapamycin to suppress AiTORC1, leading to an enhanced catabolism, a decreased antioxidant capacity, and a significant reduction in thermotolerance in bay scallops. Collectively, this study elucidates the presence, structural features, evolutional relationships, expression profiles, and roles in antioxidant capacity and metabolism regulation of AiTORC1 in the bay scallop, providing a preliminary understanding of its versatile functions in response to high-temperature challenges in marine mollusks.

Morphological and Physiological Responses of Two Tropical Rice (Oryza sativa) Varieties to High-Temperature Stress

Morphological and Physiological Responses of Two Tropical Rice (Oryza sativa) Varieties to High-Temperature Stress

PlFabG improves high-temperature resistance in herbaceous peony by increasing saturated fatty acids

The herbaceous peony (Paeonia lactiflora Pall.) is renowned for its striking flowers, which are highly valued in the cut flower industry. However, in the middle and lower reaches of the Yangtze River, the elevated summer temperatures negatively affect the plant's flowering capacity in the subsequent year. 3-oxoacyl-ACP reductase (FabG) is a component of the type II fatty acid synthesis (FAS II) system, where it plays a role in facilitating the production of saturated fatty acids. However, its role in conferring resistance to high-temperature stress remains unclear. In order to investigate the function of PlFabG in dealing with high-temperature stress, we isolated PlFabG from P. lactiflora. The gene contains an open reading frame (ORF) of 780 bp, which encodes 259 amino acids. Quantitative real-time PCR (qRT-PCR) analysis showed that the expression levels of PlFabG increased with prolonged exposure to high temperature. Additionally, plants overexpressing PlFabG maintained a relatively healthy phenotype under high-temperature stress, whereas plants with silencing PlFabG exhibited more severe leaf scorching and wilting under the same conditions. Various physiological indices indicated that PlFabG reduced reactive oxygen species (ROS) accumulation and enhanced the saturation of photosystem II. Most importantly, PlFabG helped P. lactiflora withstand high-temperature stress by increasing the proportion of saturated fatty acids, thereby maintaining cell membrane integrity. These findings elucidate the beneficial role of PlFabG in enhancing plant tolerance to high temperature and provide a strong theoretical support for the development of high-temperature tolerance in transgenic P. lactiflora.

Comparative transcriptome analysis of low- and high-latitude populations of Charybdis japonica under temperature stress

Global climate change has caused rapid temperature changes in marine environments. Understanding how marine organisms respond to temperature changes can help predict their richness of future biodiversity. In this study, we examined the gene expression levels and the difference in the pathways that are responsive to acute temperature stress in low- and high-latitude populations of the shore swimming crab, Charybdis japonica. The two populations of C. japonica were exposed to low- and high-temperature stresses (15°C and 28°C) and used for transcriptome sequencing. Genetic regulatory ability changes were compared to determine the diverse response of the two crab populations to temperature change. The gene expression levels and functional enrichment analysis showed that the low-latitude crab regulated more genes (938) that were mainly enriched in DNA replication and metabolic pathways, whereas the high-latitude crab regulated less genes (309) that were mainly enriched in genetic information processing at low-temperature stress. Furthermore, the low-latitude crab regulated less genes (33) that were mainly enriched in genetic information processing, whereas the high-latitude crab regulated more genes (280) that were mainly enriched in signal transduction and cellular process at high-temperature stress. These results implied that the low-latitude population was more resilient to high-temperature stress, while the high-latitude population was more resilient to low-temperature stress. This study enhances our understanding of how different geographic C. japonica populations respond to varying temperature environments in their living zone, which could be helpful for predicting future biodiversity trends of intertidal crustaceans under global climate change.

Exogenous Salicylic Acid Regulates Fruiting Body Development, Secondary Metabolite Accumulation, Cell Wall Integrity, and Endogenous Salicylic Acid Content under Heat Stress in Pleurotus ostreatus.

High-temperature or heat stress (HS) represents a significant environmental challenge that adversely affects crop growth and poses a substantial threat to agricultural production. Pleurotus ostreatus, recognized as the second most widely cultivated edible fungus worldwide, is particularly susceptible to the detrimental effects of HS. Enhancing the HS resistance of P. ostreatus is crucial for increasing its yield. In a prior investigation, we discovered that salicylic acid (SA) enhanced the resistance of P. ostreatus mycelia to HS through a metabolic rearrangement. The present study further investigated the effects of SA on P. ostreatus under HS. Cultivation experiments revealed that exogenous SA improved the mycelium recovery growth rate, yield, and fruiting body quality after HS. Further experiments revealed that exogenous SA mitigated the damage to the MAPK-Slt2 signal produced by HS while maintaining cell wall integrity. Furthermore, we hypothesized that the phenylalanine ammonia-lyase pathway might serve as a source for SA. In this context, we identified two salicylic hydroxylases, Po1102164 and Po1104438. Both HS and exogenous SA were found to elevate intracellular SA levels, thereby enhancing the resistance of P. ostreatus to HS.

High temperature-induced Cscaspase-8 disrupts the developmental relationship between Chilo suppressalis and its endoparasitoid

Host hemolymph is an important place of growth and development for most endoparasitoids. Immunofluorescence assay showed that parasitism induced Chilo suppressalis larvae to produce large numbers of granulocytes, but high temperatures led to granulocytes apoptosis and loss of phagocytosis. In addition, high temperatures activated the endoplasmic reticulum apoptotic pathway, leading to apoptosis of prohemocytes. In the present study, the initiator Cscaspase-8 was obtained from the rice pest C. suppressalis. The results of real-time PCR showed that Cscaspase-8 expression was highest in hemocytes; furthermore, transcription was most highly in female adults. Cscaspase-8 was significantly induced when larvae were exposed to 39 °C for a 2-h period. Cscaspase-8 expression was significantly elevated after 2 d of parasitism. Results of the interference test showed that the survival rate of C. suppressalis larvae is not affected by Cscaspase-8 gene silencing under high temperature and parasitism stress. However, developmental delays were observed in Cotesia chilonis larvae when the host Cscaspase-8 gene was knocked down. These results contribute to the current knowledge on the regulatory mechanisms of apoptosis in insects subjected to high temperature and parasitism stress.

Physiology and transcriptome profiling reveal the drought tolerance of five grape varieties under high temperatures

The evaluation of plant stress tolerance and the screening of key regulatory genes under the combined stresses of high temperature and drought are important for the study of plant stress tolerance mechanisms. In this study, the drought tolerance of five grape varieties was evaluated under high-temperature conditions to screen key genes for further exploration of resistance mechanisms. By comparing and analysing the morphological characteristics and physiological indicators associated with the response of grapevines to drought stress and integrating them with the membership function to assess the strength of their drought tolerance, the order of drought tolerance was found to be as follows: 420A>110R>CS>fercal>188-08. To further analyse the mechanism of differences in drought tolerance, transcriptomic sequencing was performed on the drought-tolerant cultivar 420A, the drought-sensitive cultivar 188-08 and the control cultivar CS. The functional analysis of differential metabolic pathways indicated that the differentially expressed genes were enriched mainly in biological that 420A had higher antioxidant activity. Moreover, the transcription factors which differentially expressed were also analysed in the five grape varieties, and several genes, such as VvAGL15, VvLBD41, and VvMYB86, appeared to be closely related to drought tolerance, suggesting their potential involvement in the regulation of grapevine drought tolerance and their value in drought tolerance research.