Soybean gene GmMLP34 regulates Arabidopsis negative response to high temperature stress.

The functions of major latex proteins (MLPs) in plant defense and stress responses have been widely documented; however, their roles in HT stress response in soybeans have not been elucidated. This study investigated the role of GmMLP34, a member of the major latex protein (MLP) family, in the response of soybeans to HT stress. Transcriptome analysis of HT-resistant (JD21) and HT-sensitive (HD14) soybean leaves under HT stress (43.40 ± 1.70 °C) and field conditions revealed differential expression of GmMLP34. Further examination across different HT-resistant varieties showed that GmMLP34 was down-regulated in the leaves of 6 HT-resistant varieties (85.7 %) and up-regulated in the leaves of 6 HT-sensitive varieties (85.7 %) under the HT treatment (45 °C for 3 h). The results of this study indicate that ectopic expression of the GmMLP34 gene in Arabidopsis led to a significant decrease in the survival rate of seedling when compared to the wild type (WT) under HT stress conditions of 37/28 °C (day/night) for 5 d, Moreover, the results indicated a significant decrease in primary root length and lateral root number under 45 °C/3 h HT stress followed by 12 h room temperature recovery. Additionally, the levels of abscisic acid (ABA), and flavonoids, and the activity of the peroxidase (POD) enzyme in the antioxidant system was decreased, while the activity of the superoxide dismutase (SOD) enzyme increased in GmMLP34-overexpressing transgenic Arabidopsis thaliana. The expression levels of the HT-response genes AtCHS1 and AtCHI2-A, were significantly down-regulated, whereas that of AtGBP1 was significantly up-regulated. These results suggest that GmMLP34 negatively regulates the response of Arabidopsis thaliana to HT stress by modulating flavonoid synthesis, hormone synthesis, and the antioxidant enzyme system. These findings provide theoretical information for the genetic improvement of HT tolerance in soybean and contribute to the understanding of the molecular mechanisms underlying plant responses to abiotic stress.

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.

Phenological Adaptation Is Insufficient to Offset Climate Change-Induced Yield Losses in US Hybrid Maize.

Climate change is projected to decrease maize yields due to warmer temperatures and their consequences. Studies using crop growth models (CGMs), however, have predicted that, through a combination of alterations to planting date, flowering time, and maturity, these yield losses can be mitigated or even reversed. Here, we examine three assumptions of such studies: (1) that climate has driven historical phenological trends, (2) that CGM ensembles provide unbiased estimates of yields under high temperatures, and (3) that the effects of temperature on yields are an emergent property of interactions between phenology and environment. We used data on maize phenology from the United States Department of Agriculture, a statistical model of maize hybrid heat tolerance derived from 80 years of public yield trial records across four US states, and outputs of an ensemble of CMIP6 climate models. While planting dates have advanced historically, we found a trend toward later planting dates after 2005 and no trend for silking or maturity, shifting more time into the reproductive period. We then projected maize yields using the historical model and crop calendars devised using three previously proposed adaptation strategies. In contrast to studies using CGMs, our statistical yield model projected severe yield losses under all three strategies. Finally, we projected maize yields accounting for historical genetic variability for heat tolerance, discovering that it was insufficient to overcome the negative effects of projected warming. These projections are driven by greater heat stress exposure under all crop calendars and climate scenarios. Combined with analysis of the internal sensitivities of CGMs to temperature, our results suggest that current projections do not adequately account for the effects of increasing temperatures on maize yields. Climate adaptation in the US Midwest must utilize a richer set of strategies than phenological adaptation, including improvements to heat tolerance and crop diversification.

Effects of High-Temperature Stress on Biological Characteristics of Coccophagus japonicus Compere.

The parasitoid, Coccophagus japonicus Compere (Hymenoptera: Aphelinidae) is a dominant natural enemy of Parasaissetia nigra Nietner (Hemiptera: Coccidae), an important pest of rubber trees. Much of Chinese rubber is cultivated in hotter regions such as Yunnan and Hainan, exposing applied parasitoids to non-optimal temperatures. Therefore, C. japonicus must adapt to avoid temperature-related impacts on survival and population expansion. In this study, we monitored the survival rate, developmental duration, parasitism rate, and fecundity of C. japonicus during short-term exposures to 36 °C, 38 °C, and 40 °C for 2, 4, and 6 h, as well as continuous exposures to 32 °C and 34 °C for 3 days. The results show that short-term exposure to high-temperature stress leads to decreased survival rate of C. japonicus larvae and pupae, with survival rates declining as temperature and duration increase. High-temperature stress also delayed insect development, reduced mature egg production, shortened the body length of newly emerged females, and decreased female lifespans. Moreover, continuous high-temperature stress was found to significantly impact the development and reproduction of C. japonicus. Compared with the CK (27 °C), 3 d of continuous exposure to 34 °C prolonged developmental duration, shortened the body length and lifespan of newly emerged females, reduced survival rate and single female fecundity, and significantly decreased offspring numbers and parasitism rates. Temperatures of 36 °C, 38 °C, and 40 °C decreased the mortality time of adult females to 28.78, 16.04, and 7.91 h, respectively. Adverse temperatures also affected the insects' functional response, with 8 h of stress at 36 °C, 38 °C, and 40 °C causing the control efficiency of C. japonicus on P. nigra. This level of stress in the parasitoids was found to reduce the immediate attack rate and search effect, prolong processing time, and attenuate interference between small prey. Parasitoid efficiency was lowest following exposure to 40 °C. In this study, we determined the range of high temperatures that C. japonicus populations can tolerate under short- or long-term stress, providing guidance for future field applications.

High-temperature stress in strawberry: understanding physiological, biochemical and molecular responses.

MAIN CONCLUSION: Heat stress reduces strawberry growth and fruit quality by impairing photosynthesis, disrupting hormone regulation, and altering mineral nutrition. Multi-omics studies show extensive transcriptional, post-transcriptional, proteomic and metabolomic under high temperatures. Garden strawberry is a globally cultivated, economically important fruit crop highly susceptible to episodic heat waves and chronically rising temperatures associated with climate change. Heat stress negatively affects the growth, development, and quality of strawberries. Elevated temperatures affect photosynthesis, respiration, water balance, hormone signaling, and carbohydrate metabolism in strawberries. Heat stress reduces the size and number of leaves, the number of crowns, the differentiation of flower buds, and the viability of pollen and fruit set, ultimately leading to a lower yield. On a physiological level, heat stress reduces membrane stability, increases the production of reactive oxygen species, and reduces the antioxidant capacity of strawberries. Heat-tolerant varieties have better physiological and biochemical adaptation mechanisms compared to heat-sensitive varieties. Breeding heat-tolerant strawberry cultivars involves selection for traits such as increased leaf temperature, membrane thermostability, and chlorophyll content. Multi-omics studies show extensive transcriptional, post-transcriptional, proteomic, metabolomic, and ionomic reprogramming at high temperatures. Integrative-omics approaches combine multiple omics datasets to obtain a systemic understanding of the responses to heat stress in strawberries. This article summarizes the deciphering of strawberry responses to heat stress using physiological, biochemical, and molecular approaches that will enable the development of resilient adaptation strategies that sustain strawberry production under global climate change.

Individual and combined effects of high-temperature stress at booting and flowering stages on rice grain quality.

BACKGROUND: High temperature stress (HTS) has become a serious threat to rice grain quality and few studies have examined the effects of HTS across multiple stages on rice grain quality. In the present study, we conducted 2 years of HTS treatments under three temperature regimes (32/22 °C, 40/30 °C and 44/34 °C) and HTS durations of 2 days and 4 days at three critical stages: booting, flowering, and a combination of booting and flowering. We employed the heat degree days (HDD) metric, which accounts for both the level and duration of HTS, to quantify the relationships between grain quality traits and HTS. RESULTS: The results revealed the diverse effects of HTS on rice grain quality at different stages, durations and temperature levels. HTS significantly (P < 0.05) reduced grain quality, with the highest sensitivities (reduction per 1 °C day-1 increase in HDD) observed at the flowering stage, followed by the combined and booting stages treatments under mild HTS treatment (40/30 °C). However, under extreme HTS treatments (44/34 °C) for 4 days, rice grains subjected to combined HTS treatment experienced complete mortality. CONCLUSION: Pre-exposed to HTS at the booting stage within a certain intensity can alleviate the adverse effects of post-flowering HTS on grain quality. This provides valuable insights for assessing the potential impact of multiple HTS events on the grain quality under future climate warming. © 2024 Society of Chemical Industry.

Interactions between root endophytic microorganisms and the reduced negative ion release capacity of Phalaenopsis aphrodite Rchb. f. under high temperature stress.

Introduction: Negative oxygen ions are produced by plants through photosynthesis, utilizing "tip discharge" or the photoelectric effect, which has various functions such as sterilization, dust removal, and delaying aging. With global warming, high temperatures may affect the ability of Phalaenopsis aphrodite Rchb. f. to produce negative oxygen ions. P. aphrodite is commonly used in modern landscape planning and forest greening. Methods: In this study, P. aphrodite was selected as the research object. By artificially simulating the climate, the control group (CK) and the high temperature stress group (HS) were set up in the experiment. Results: The study found that compared with the control group, the ability of P. aphrodite to produce negative oxygen ions significantly decreased when exposed to high temperature stress. Meanwhile, under high temperature stress treatment, peroxidase content increased by 102%, and proline content significantly increased by 35%. Discussion: Redundancy analysis results indicated a significant correlation between the root endophytic microbial community of P. aphrodite and negative oxygen ions, as well as physiological indicators. Under high temperature stress, P. aphrodite may affect the regulation of physiological indicators by modifying the composition of root endophytic microbial communities, thereby influencing the ability to release negative oxygen ions.

Comprehensive transcriptome analysis unravels the perturbated cardiovascular-related molecular mechanisms of tilapia under high-temperature stress.

With the ongoing intensification of global warming, thermal stress poses significant challenges to tilapia aquaculture. However, the molecular mechanisms underlying the cardiac response of tilapia to high temperatures remain largely unexplored. To address this knowledge gap, we investigated the effects of high-temperature stress on the transcriptomic landscape of the tilapia heart. RNA sequencing was performed on the hearts of Oreochromis aureus (AR), Oreochromis niloticus (NL), and hybrids (O. niloticus ♀ × O. aureus ♂, AN) under treatments of 28 °C, 36 °C, and 39 °C. Using a multi-method approach, including Differentially Expressed Genes analysis, Weighted Gene Co-expression Network Analysis, Fuzzy C-Means, Self-Organizing Map, and Support Vector Machine-Recursive Feature Elimination, we identified six marker genes at 39 °C (AR: ptges3, tuba1a; NL: ran, tcima; AN: slc16a1, fam184b). These genes exhibited strong positive correlations and increased expression under high-temperature conditions. Gene Set Enrichment Analysis and GENIE3 revealed that these marker genes closely regulate three cardiovascular-related pathways: adrenergic signaling in cardiomyocytes, vascular smooth muscle contraction, and cardiac muscle contraction. We hypothesize that the synergistic inhibition of these pathways by marker genes leads to the deterioration of cardiovascular function. In summary, thermal stress activates marker genes, which in turn inhibit cardiovascular pathways, impairing cardiac performance. We propose that these marker genes could serve as dynamic thermal indicators of cardiac performance in tilapia. Additionally, our findings provide theoretical support for improving the management of tilapia farming under high-temperature stress.

Identification and Analysis of the Superoxide Dismutase (SOD) Gene Family and Potential Roles in High-Temperature Stress Response of Herbaceous Peony (Paeonia lactiflora Pall.).

The herbaceous peony (Paeonia lactiflora Pall.) plant is world-renowned for its ornamental, medicinal, edible, and oil values. As global warming intensifies, its growth and development are often affected by high-temperature stress, especially in low-latitude regions. Superoxide dismutase (SOD) is an important enzyme in the plant antioxidant systems and plays vital roles in stress response by maintaining the dynamic balance of reactive oxygen species (ROS) concentrations. To reveal the members of then SOD gene family and their potential roles under high-temperature stress, we performed a comprehensive identification of the SOD gene family in the low-latitude cultivar 'Hang Baishao' and analyzed the expression patterns of SOD family genes (PlSODs) in response to high-temperature stress and exogenous hormones. The present study identified ten potential PlSOD genes, encoding 145-261 amino acids, and their molecular weights varied from 15.319 to 29.973 kDa. Phylogenetic analysis indicated that PlSOD genes were categorized into three sub-families, and members within each sub-family exhibited similar conserved motifs. Gene expression analysis suggested that SOD genes were highly expressed in leaves, stems, and dormancy buds. Moreover, RNA-seq data revealed that PlCSD1-1, PlCSD3, and PlFSD1 may be related to high-temperature stress response. Finally, based on the Quantitative Real-time PCR (qRT-PCR) results, seven SOD genes were significantly upregulated in response to high-temperature stress, and exogenous EBR and ABA treatments can enhance high-temperature tolerance in P. lactiflora. Overall, these discoveries lay the foundation for elucidating the function of PlSOD genes for the thermotolerance of herbaceous peony and facilitating the genetic breeding of herbaceous peony cultivars with strong high-temperature resistance.

PlPOD45 positively regulates high-temperature tolerance of herbaceous peony by scavenging reactive oxygen species.

Herbaceous peony (Paeonia lactiflora Pall.) is a widely used famous traditional flower in China. It prefers cold and cool climate, but is not resistant to high temperature during summer in the middle and lower reaches of the Yangtze River. Previously, we found peroxidase (POD) is an important antioxidant enzyme that played an important role in high-temperature tolerance of P. lactiflora. The present study isolated the candidate gene PlPOD45 and verified its function in resisting high-temperature stress. And the results showed that PlPOD45 had an open reading frame of 978 bp that encoded 325 amino acids. Its protein was localized to the cell membrane and cytoplasm. High-temperature stress induced PlPOD45 expression. Heterologous overexpression of PlPOD45 improved plant tolerance to high-temperature stress, decreased reactive oxygen species (ROS) accumulation, relative electrical conductivity and malondialdehyde content, and increased the ratio of variable fluorescence to highest fluorescence and POD activity. Conversely, silencing PlPOD45 in P. lactiflora could decrease POD activity, ROS scavenging capability and cell membrane stability when these plants were exposed to high-temperature stress. These results suggest that PlPOD45 positively regulates high-temperature tolerance through ROS scavenging, which would provide a theoretical basis for improving high-temperature tolerance in P. lactiflora. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01505-x.

Comparative transcriptomic and metabolomic analyses provide insights into the responses to high temperature stress in Alfalfa (Medicago sativa L.).

High temperature stress is one of the most severe forms of abiotic stress in alfalfa. With the intensification of climate change, the frequency of high temperature stress will further increase in the future, which will bring challenges to the growth and development of alfalfa. Therefore, untargeted metabolomic and RNA-Seq profiling were implemented to unravel the possible alteration in alfalfa seedlings subjected to different temperature stress (25 ℃, 30 ℃, 35 ℃, 40 ℃) in this study. Results revealed that High temperature stress significantly altered some pivotal transcripts and metabolites. The number of differentially expressed genes (DEGs) markedly up and down-regulated was 1876 and 1524 in T30_vs_CK, 2, 815 and 2667 in T35_vs_CK, and 2115 and 2, 226 in T40_vs_CK, respectively. The number for significantly up-regulated and down-regulated differential metabolites was 173 and 73 in T30_vs_CK, 188 and 57 in T35_vs_CK, and 220 and 66 in T40_vs_CK, respectively. It is worth noting that metabolomics and transcriptomics co-analysis characterized enriched in plant hormone signal transduction (ko04705), glyoxylate and dicarboxylate metabolism (ko00630), from which some differentially expressed genes and differential metabolites participated. In particular, the content of hormone changed significantly under T40 stress, suggesting that maintaining normal hormone synthesis and metabolism may be an important way to improve the HTS tolerance of alfalfa. The qRT-PCR further showed that the expression pattern was similar to the expression abundance in the transcriptome. This study provides a practical and in-depth perspective from transcriptomics and metabolomics in investigating the effects conferred by temperature on plant growth and development, which provided the theoretical basis for breeding heat-resistant alfalfa.

Effects of high temperature on the growth performance and midgut autophagy of thermotolerant and thermosensitive silkworm strains.

High temperature stress has long-term negative effects on the growth and development of silkworm (Bombyx mori). Different silkworm varieties show the different tolerance to high temperature. The induction of autophagy is linked to increased thermotolerance in diverse ectothermic organisms. However, the function of autophagy in the thermotolerant and thermosensitive silkworm strains under high-temperature conditions remains unclear. The thermotolerant Liangguang NO.2 and thermosensitive Jingsong × Haoyue strains were used to explore the role of autophagy in thermotolerance. Here, we first found that the larval body weight gain was increased in the thermosensitive Jingsong × Haoyue strain, but there was no difference in the thermotolerant Liangguang NO.2 strain under high temperature conditions. High temperature stress had a negative influence on the cocoon performance in both the Liangguang NO.2 and Jingsong × Haoyue strains. Additionally, the autophagy-related gene Atg5 mRNA expression in the Liangguang NO.2 strain was upregulated by high temperature, while the expression of Atg12 mRNA was reduced in the Jingsong × Haoyue strain. Titers of 20-Hydroxyecdysone and the ultraspiracle 1 mRNA expression in the Liangguang NO.2 strain were upregulated by high temperature, which might be associated with the induction of autophagy. These results demonstrate the potentially regulatory mechanism of autophagy in silkworms' tolerance to high temperature, providing a theoretical basis for exploring the physiological mechanism of thermotolerance in insects.

Ribosome Profiling and RNA Sequencing Reveal Translation and Transcription Regulation under Acute Heat Stress in Rainbow Trout (Oncorhynchus mykiss, Walbaum, 1792) Liver.

Rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) is an important economic cold-water fish that is susceptible to heat stress. To date, the heat stress response in rainbow trout is more widely understood at the transcriptional level, while little research has been conducted at the translational level. To reveal the translational regulation of heat stress in rainbow trout, in this study, we performed a ribosome profiling assay of rainbow trout liver under normal and heat stress conditions. Comparative analysis of the RNA-seq data with the ribosome profiling data showed that the folding changes in gene expression at the transcriptional level are moderately correlated with those at the translational level. In total, 1213 genes were significantly altered at the translational level. However, only 32.8% of the genes were common between both levels, demonstrating that heat stress is coordinated across both transcriptional and translational levels. Moreover, 809 genes exhibited significant differences in translational efficiency (TE), with the TE of these genes being considerably affected by factors such as the GC content, coding sequence length, and upstream open reading frame (uORF) presence. In addition, 3468 potential uORFs in 2676 genes were identified, which can potentially affect the TE of the main open reading frames. In this study, Ribo-seq and RNA-seq were used for the first time to elucidate the coordinated regulation of transcription and translation in rainbow trout under heat stress. These findings are expected to contribute novel data and theoretical insights to the international literature on the thermal stress response in fish.

Wheat TaNACα18 functions as a positive regulator of high-temperature adaptive responses and improves cell defense machinery.

Global wheat production amounted to >780 MMT during 2022-2023 whose market size are valued at >$128 billion. Wheat is highly susceptible to high-temperature stress (HTS) throughout the life cycle and its yield declines 5-7% with the rise in each degree of temperature. Previously, we reported an array of HTS-response markers from a resilient wheat cv. Unnat Halna and described their putative role in heat acclimation. To complement our previous results and identify the key determinants of thermotolerance, here we examined the cytoplasmic proteome of a sensitive cv. PBW343. The HTS-triggered metabolite reprograming highlighted how proteostasis defects influence the formation of an integrated stress-adaptive response. The proteomic analysis identified several promising HTS-responsive proteins, including a NACα18 protein, designated TaNACα18, whose role in thermotolerance remains unknown. Dual localization of TaNACα18 suggests its crucial functions in the cytoplasm and nucleus. The homodimerization of TaNACα18 anticipated its function as a transcriptional coactivator. The complementation of TaNACα18 in yeast and overexpression in wheat demonstrated its role in thermotolerance across the kingdom. Altogether, our results suggest that TaNACα18 imparts tolerance through tight regulation of gene expression, cell wall remodeling and activation of cell defense responses.

Genome-Wide Identification and Characterization of RdHSP Genes Related to High Temperature in Rhododendron delavayi.

Heat shock proteins (HSPs) are molecular chaperones that play essential roles in plant development and in response to various environmental stresses. Understanding R. delavayi HSP genes is of great importance since R. delavayi is severely affected by heat stress. In the present study, a total of 76 RdHSP genes were identified in the R. delavayi genome, which were divided into five subfamilies based on molecular weight and domain composition. Analyses of the chromosome distribution, gene structure, and conserved motif of the RdHSP family genes were conducted using bioinformatics analysis methods. Gene duplication analysis showed that 15 and 8 RdHSP genes were obtained and retained from the WGD/segmental duplication and tandem duplication, respectively. Cis-element analysis revealed the importance of RdHSP genes in plant adaptations to the environment. Moreover, the expression patterns of RdHSP family genes were investigated in R. delavayi treated with high temperature based on our RNA-seq data, which were further verified by qRT-PCR. Further analysis revealed that nine candidate genes, including six RdHSP20 subfamily genes (RdHSP20.4, RdHSP20.8, RdHSP20.6, RdHSP20.3, RdHSP20.10, and RdHSP20.15) and three RdHSP70 subfamily genes (RdHSP70.15, RdHSP70.21, and RdHSP70.16), might be involved in enhancing the heat stress tolerance. The subcellular localization of two candidate RdHSP genes (RdHSP20.8 and RdHSP20.6) showed that two candidate RdHSPs were expressed and function in the chloroplast and nucleus, respectively. These results provide a basis for the functional characterization of HSP genes and investigations on the molecular mechanisms of heat stress response in R. delavayi.

c-Jun N-terminal kinase 1/P53 signaling mediates intrinsic apoptosis of largemouth bass (Micropterus salmoides) hepatocytes under heat stress.

The increasing frequency of high-temperature extremes threatens largemouth bass Micropterus salmoides, a significant fish for freshwater ecosystems and aquaculture. Our previous studies at the transcript level suggested that heat stress induces hepatic apoptosis in largemouth bass. In the current study, we sought to validate these findings and further investigate the role of the c-Jun N-terminal kinase (JNK)/P53 signaling in hepatic apoptosis under heat stress. First, heat treatments were conducted in vivo and in vitro under different temperatures: 28 °C, 32 °C, and 37 °C. In primary hepatocytes subjected to heat treatment, cell viability was evaluated via the Cell Counting Kit-8, while mitochondrial membrane potential and nuclear morphology were assessed through JC-1 and Hoechst 33258 staining, respectively. We observed reductions in both cell viability and mitochondrial membrane potential (ΔΨm), along with alterations in nuclear morphology, in primary hepatocytes exposed to heat stress at temperatures of 32 °C and 37 °C. Quantitative real-time PCR revealed significant alterations in the expression profiles of intrinsic apoptosis-related genes within liver tissues under heat stress. Immunohistochemistry analysis revealed that JNK1 signaling increased as the temperature increased, JNK2 expression increased only at 37 °C, and JNK3 expression did not change with temperature. We speculate that JNK1 and JNK2 have pro- and anti-apoptotic effects, respectively. Western blot analysis conducted on cultured hepatocytes further validated these findings. JNK inhibition reduced hepatocyte apoptosis, improved nuclear morphology, and maintained ΔΨm even after 37 °C treatment. These results not only confirm that heat stress led to intrinsic apoptosis of hepatocytes but also indicated that JNK1 could mediate P53 expression and activate caspase-dependent intrinsic apoptosis in largemouth bass hepatocytes under such conditions. This study illuminates the physiological responses of largemouth bass to acute heat stress, offering valuable insights into the potential impacts of climate change on freshwater fishes and the sustainability of aquaculture.

The involvement of CaMKKI in activating AMPKα in yesso scallop Patinopecten yessoensis under high temperature stress.

Calcium/calmodulin dependent protein kinase kinase (CaMKK), a highly conserved protein kinase, is involved in the downstream processes of various biological activities by phosphorylating and activating 5'-AMP-activated protein kinase (AMPK) in response to the increase of cytosolic-free calcium (Ca2+). In the present study, a CaMKKI was identified from Yesso scallop Patinopecten yessoensis. Its mRNA was ubiquitously expressed in haemocytes and all tested tissues with the highest expression level in mantle. The expression level of PyCaMKKI mRNA in adductor muscle was significantly upregulated at 1, 3 and 6 h after high temperature treatment (25 °C), which was 3.43-fold (p < 0.05), 5.25-fold (p < 0.05), and 5.70-fold (p < 0.05) of that in blank group, respectively. At 3 h after high temperature treatment (25 °C), the protein level of PyAMPKα, as well as the phosphorylation level of PyAMPKα at Thr170 in adductor muscle, and the positive co-localized fluorescence signals of PyCaMKKI and PyAMPKα in haemocyte all increased significantly (p < 0.05) compared to blank group (18 °C). The pull-down assay showed that rPyCaMKKI and rPyAMPKα could bind each other in vitro. After PyCaMKKI was silenced by siRNA, the mRNA and protein levels of PyCaMKKI and PyAMPKα, and the phosphorylation level of PyAMPKα at Thr170 in adductor muscle were significantly down-regulated (p < 0.05) compared with the negative control group receiving an injection of siRNA-NC. These results collectively suggested that PyCaMKKI was involved in the activation of PyAMPKα in response to high temperature stress and would be helpful for understanding the function of PyCaMKKI-PyAMPKα pathway in maintaining energy homeostasis under high temperature stress in scallops.

The involvement of CgRHIM-containing protein in regulating haemocyte apoptosis after high temperature stress in Pacific oyster Crassostrea gigas.

The interactions induced by RIP homotypic interaction motif (RHIM) are essential for the activation of inflammatory signaling and certain cell death pathways. In the present study, a RHIM-containing protein was identified from Pacific oyster Crassostrea gigas, which harbored a RHIM domain and a Death domain (designated CgRHIM-containing protein). The mRNA transcripts of CgRHIM-containing protein were constitutively expressed in all the examined tissues of oysters, with the highest expression level in mantle. The CgRHIM-containing protein was mainly distributed in the cytoplasm of oyster haemocytes. After high temperature stress, the expression levels of CgRel and CgBcl-2 increased significantly, and reached the peak level at 12 h, then decreased gradually. The transcripts of CgRHIM-containing protein, Cgcaspase-8 and Cgcaspase-3 in haemocytes up-regulated at 12 h after high temperature stress. Moreover, the protein abundance of CgRHIM-containing protein increased significantly, and the ubiquitination level of CgRHIM-containing protein in haemocytes showed an increasing trend at first and then decreased. After the expression of CgRHIM-containing protein was knocked down by siRNA, the mRNA expression levels of CgRel and CgBcl-2 decreased significantly at 6 h after high temperature stress, and those of CgFADD-like, Cgcaspase-8 and Cgcaspase-3, as well as the apoptosis rate of haemocytes also decreased significantly at 24 h. These results indicated that CgRHIM-containing protein might regulate haemocyte apoptosis in oysters upon high temperature stress via mediating the expression of Rel, Bcl-2 and caspase-8/3.

Unraveling the genetic and molecular basis of heat stress in cotton.

Human activities and climate change have resulted in frequent and intense weather fluctuations, leading to diverse abiotic stresses on crops which hampers greatly their metabolic activities. Heat stress, a prevalent abiotic factor, significantly influences cotton plant biological activities resulting in reducing yield and production. We must deepen our understanding of how plants respond to heat stress across various dimensions, encompassing genes, RNAs, proteins, metabolites for effective cotton breeding. Multi-omics methods, primarily genomics, transcriptomics, proteomics, metabolomics, and phenomics, proves instrumental in studying cotton's responses to abiotic stresses. Integrating genomics, transcriptomics, proteomics, and metabolomic is imperative for our better understanding regarding genetics and molecular basis of heat tolerance in cotton. The current review explores fundamental omics techniques, covering genomics, transcriptomics, proteomics, and metabolomics, to highlight the progress made in cotton omics research.

PtWRKY2, a WRKY transcription factor from Pinellia ternata confers heat tolerance in Arabidopsis.

High temperatures are a major stress factor that limit the growth of Pinellia ternata. WRKY proteins widely distribute in plants with the important roles in plant growth and stress responses. However, WRKY genes have not been identified in P. ternata thus far. In this study, five PtWRKYs with four functional subgroups were identified in P. ternata. One group III WRKY transcription factor, PtWRKY2, was strongly induced by high temperatures, whereas the other four PtWRKYs were suppressed. Analysis of transcription factor characteristics revealed that PtWRKY2 localized to the nucleus and specifically bound to W-box elements without transcriptional activation activity. Overexpression of PtWRKY2 increased the heat tolerance of Arabidopsis, as shown by the higher percentage of seed germination and survival rate, and the longer root length of transgenic lines under high temperatures compared to the wild-type. Moreover, PtWRKY2 overexpression significantly decreased reactive oxygen species accumulation by increasing the catalase, superoxide dismutase, and peroxidase activities. Furthermore, the selected heat shock-associated genes, including five transcription factors (HSFA1A, HSFA7A, bZIP28, DREB2A, and DREB2B), two heat shock proteins (HSP70 and HSP17.4), and three antioxidant enzymes (POD34, CAT1, and SOD1), were all upregulated in transgenic Arabidopsis. The study identifies that PtWRKY2 functions as a key transcriptional regulator in the heat tolerance of P. ternata, which might provide new insights into the genetic improvement of P. ternata.