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Heat stress (HS) severely affects the growth and yield of rice, necessitating a clear understanding of the molecular mechanisms underlying HS tolerance. In this study, we report that the Aux/IAA family gene, OsIAA7, whose expression is induced by HS and positively regulates HS tolerance in rice (Oryza sativa L.). The osiaa7 mutant exhibits reduced HS tolerance, whereas overexpression of OsIAA7 enhances it. Our findings suggest that OsIAA7 contributes to HS tolerance by reducing hydrogen peroxide accumulation and cell death. Physiological analysis indicates that OsIAA7 influences the levels of malondialdehyde, catalase, and chlorophyll A concentration in plants under HS conditions. RNA-seq analysis suggests that OsIAA7 modulates the expression of heat-responsive genes, contributing to HS tolerance. Further, biochemical analyses demonstrate a physical interaction between OsIAA7 and OsARF6, with OsIAA7 inhibiting the activity of OsARF6. RT-qPCR results support the notion that the positive regulatory factor OsIAA7 and the negative regulatory factor OsARF6 control HS tolerance by regulating the transcript levels of OsTT1 and OsTT3.1. Together, our results reveal the role of OsIAA7 in controlling HS tolerance through the modulation of physiological processes and the inhibition of OsARF6 activity, suggesting that some Aux/IAA family genes play a role in heat tolerance in rice., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Heat stress (HS) has become a major factor limiting crop yields worldwide. HS inhibits plant growth by ROS accumulation, and NADPH oxidases (Rbohs) are major ROS producers in plants. Here, we show that CRISPR/Cas knockout of the OsRbohB (OsRbohB-KO) significantly increased rice tolerance to HS imposed at various different growth stages. We produced OsRbohB-KO and OsRbohB-overexpression (OsRbohB-OE) lines in a japonica cultivar, Nipponbare. Compared with nontransgenic wild-type (WT) plants, the OsRbohB-KO lines showed a significant increase in chlorophyll contents (5.2%-58.0%), plant growth (48.2%-65.6%) and grain yield (8.9%-20.5%), while reducing HS-induced ROS accumulation in seeds (21.3%-33.0%), seedlings (13.0%-30.4%), anthers (13.1%-20.3%) and grains (9.7%-22.1%), under HS conditions. Analysis of yield components revealed that the increased yield of OsRbohB-KO plants was due to increased starch synthetase activity, spikelets per panicle (2.0%-9.3%), filled spikelets (4.8%-15.5%), percentage of filled spikelets (2.4%-6.8%) and 1000-grain weight (2.9%-7.4%) under HS conditions during the reproductive stage. Grain milling and appearance quality, and starch content were also significantly increased in OsRbohB-KO plants under HS conditions during the mature stage. Furthermore, OsRbohB-KO significantly upregulated the expression levels of heat shock-related genes, OsHSP23.7, OsHSP17.7, OsHSF7 and OsHsfA2a, in rice seedlings and grains under long-term HS conditions. Conversely, OsRbohB-OE resulted in phenotypes that were opposite to OsRbohB-KO in most cases. Our results suggest that suppression of OsRbohB provides an effective approach for alleviating heat damage and improving grain yield and quality of rice under long-term HS conditions., (© 2024 The Author(s). Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.)

As global temperatures rise, improving crop yields will require enhancing the thermotolerance of crops. One approach for improving thermotolerance is using bioengineering to increase the thermostability of enzymes catalysing essential biological processes. Photorespiration is an essential recycling process in plants that is integral to photosynthesis and crop growth. The enzymes of photorespiration are targets for enhancing plant thermotolerance as this pathway limits carbon fixation at elevated temperatures. We explored the effects of temperature on the activity of the photorespiratory enzyme glycerate kinase (GLYK) from various organisms and the homologue from the thermophilic alga Cyanidioschyzon merolae was more thermotolerant than those from mesophilic plants, including Arabidopsis thaliana. To understand enzyme features underlying the thermotolerance of C. merolae GLYK (CmGLYK), we performed molecular dynamics simulations using AlphaFold-predicted structures, which revealed greater movement of loop regions of mesophilic plant GLYKs at higher temperatures compared to CmGLYK. Based on these simulations, hybrid proteins were produced and analysed. These hybrid enzymes contained loop regions from CmGLYK replacing the most mobile corresponding loops of AtGLYK. Two of these hybrid enzymes had enhanced thermostability, with melting temperatures increased by 6 °C. One hybrid with three grafted loops maintained higher activity at elevated temperatures. Whilst this hybrid enzyme exhibited enhanced thermostability and a similar K m for ATP compared to AtGLYK, its K m for glycerate increased threefold. This study demonstrates that molecular dynamics simulation-guided structure-based recombination offers a promising strategy for enhancing the thermostability of other plant enzymes with possible application to increasing the thermotolerance of plants under warming climates., (© 2024 The Author(s). Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.)

With climate change projections indicating an increase in the frequency of extreme heat events and irregular rainfall patterns globally, the threat to global food security looms large. Terminal heat stress, which occurs during the critical reproductive stage, significantly limits lentil productivity. Therefore, there is an urgent need to improve lentil's resilience to heat stress to sustain production. However, studies identifying heat-tolerant sources in lentils are limited. To address these issues, we assessed 158 lentil genotypes under normal and late-sown conditions over two consecutive seasons. We employed eleven heat stress indices to identify lines tolerant to heat stress. All genotypes exhibited a decrease in average grain yield when subjected to stress conditions as compared to non-stress conditions, indicating the impact of heat stress on crop yield. Correlation analysis showed significant positive correlation between yield in normal and late-sown conditions and the following heat stress indices: STI, MP, MRP, YI, GMP, and HM. In contrast, TOL, SSPI, and PYR showed negative associations with yield in late-sown conditions. Based on these indices, we identified the genotypes P13143, P13130, and P13135 as high-yielding in both stress and non-stress conditions. Cluster analysis and biplot display in PCA also confirmed that genotypes P13143, P13130, and P13135 exhibited suitability and high yield potential in both environments. These genotypes can be utilized as donors in future breeding programs to introduce genetic variations for improving heat stress tolerance in lentil., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

AMPK is a key regulator of metabolism in eukaryotes across various pathways related to energy regulation. Although extensive investigations of AMPK have been conducted in mammals and some model organisms, research on AMPK in scallops is comparatively limited. In this study, three AMPK family genes (AiAMPKα, AiAMPKβ and AiAMPKγ) in scallop Argopecten irradians irradians were identified through genome scanning. Structure prediction and phylogenetic analyses of AiAMPKs were performed to determine their structural features and evolutionary relationships. Spatiotemporal expression patterns of AiAMPKs at different developmental stages and in healthy adult tissues were analyzed to elucidate the function of AiAMPKs in bay scallops' growth and development. The spatiotemporally specific expression of AiAMPKs implied their important roles in growth and development of bay scallops. Heat stress experiment was performed to determine the regulations of AiAMPKs in four kinds of thermosensitive tissues. Expression profiles revealed distinct molecular mechanisms of AiAMPKs in different tissues in response to heat stress: significant down-regulations in mobile hemocytes, but dominant up-regulations occurring in stationary gills, mantles and hearts. Functional verification including knock-down of AiAMPKα and inhibition of AiAMPK was separately conducted in the thermotolerant tissue heart at the post-transcription and translation levels. The thermotolerant index Arrhenius break temperature (ABT) showed a significant decrease and the rate-amplitude product (RAP) peaked earlier in the individuals after RNAi targeting AiAMPKα, displaying an earlier transition to anaerobic metabolism under heat stress, indicating an impairing ability of aerobic metabolism. After AiAMPK inhibition, widespread down-regulations of genes in key energy metabolism pathways, RNA polymerase II-mediated transcription, and aminoacyl-tRNA synthesis pathways were obviously observed, revealing the post-translational inhibition of AiAMPK hindered cardiac energy metabolism, basal transcription and translation. Overall, our findings provide evidences for exploring the molecular mechanisms of energy regulation in thermotolerant traits in bay scallops under ongoing global warming., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Heat stress negatively affects dairy cow production, and health, leading to significant losses. Identifying mechanisms associated with heat tolerance is crucial for developing breeding strategies. Circular RNAs (circRNAs), a type of noncoding RNA, regulate cell functions like autophagy, apoptosis and proliferation. In this study, dairy cows were classified into heat stress tolerant (HST, n = 15) and heat stress sensitive (HSS, n = 15) groups based on respiratory and drooling score during the heat stress. A significant difference in milk production decline was observed, with the HST group showing less decline, indicating better heat tolerance. Blood transcriptomics analysis identified 166 differentially expressed circRNAs with circRNA3685 being highlighted as a key candidate linked to heat tolerance. Overexpression of circRNA3685 in bovine mammary (MAC-T) cells inhibited autophagy and apoptosis. The circRNA3685 was found to interact with bta-miR-138, targeting HIF1A. These findings provide insights into circRNAs' role in heat stress adaptation in dairy cows.

Climate warming is expected to shift the distributions of mosquitoes and mosquito-borne diseases, promoting expansions at cool range edges and contractions at warm range edges. However, whether mosquito populations could maintain their warm edges through evolutionary adaptation remains unknown. Here, we investigate the potential for thermal adaptation in Aedes sierrensis , a congener of the major disease vector species that experiences large thermal gradients in its native range, by assaying tolerance to prolonged and acute heat exposure, and its genetic basis in a diverse, field-derived population. We found pervasive evidence of heritable genetic variation in mosquito heat tolerance, and phenotypic trade-offs in tolerance to prolonged versus acute heat exposure. Further, we found genomic variation associated with prolonged heat tolerance was clustered in several regions of the genome, suggesting the presence of larger structural variants such as chromosomal inversions. A simple evolutionary model based on our data estimates that the maximum rate of evolutionary adaptation in mosquito heat tolerance will exceed the projected rate of climate warming, implying the potential for mosquitoes to track warming via genetic adaptation., Competing Interests: Competing interests statement:The authors declare no competing interest.

Heat stress adversely impacts plant growth, development, and grain yield. Heat shock factors (Hsf), especially the HsfA2 subclass, play a pivotal role in the transcriptional regulation of genes in response to heat stress. In this study, the coding sequence of maize ZmHsf17 was cloned. ZmHsf17 contained conserved domains including a DNA binding domain, oligomerization domain, and transcriptional activation domain. The protein was nuclear localized and had transcription activation activity. Yeast two-hybrid and split luciferase complementation assays confirmed the interaction of ZmHsf17 with members of the maize HsfA2 subclass. Overexpression of ZmHsf17 in maize significantly increased chlorophyll content and net photosynthetic rate, and enhanced the stability of cellular membranes. Through integrative analysis of ChIP-seq and RNA-seq datasets, ZmPAH1, encoding phosphatidic acid phosphohydrolase of lipid metabolic pathways, was identified as a target gene of ZmHsf17. The promoter fragment of ZmPAH1 was bound by ZmHsf17 in protein-DNA interaction experiments in vivo and in vitro. Lipidomic data also indicated that the overexpression of ZmHsf17 increased levels of some critical membrane lipid components of maize leaves under heat stress. This research provides new insights into the role of the ZmHsf17-ZmPAH1 module in regulating thermotolerance in maize., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Main Conclusion: PME12-mutated plants displayed altered stomatal characteristics and susceptibility to ABA-induced closure. Despite changes in PME activity, the mutant exhibited enhanced thermotolerance. These findings suggest a complex interplay between pectin methylesterification, ABA response, and stomatal function, contributing to plant adaptation to heat stress. Pectin, an essential component of plant cell walls, is synthesized in the Golgi apparatus and deposited into the cell wall in a highly methylesterified form. The degree and distribution of methylesterification within homogalacturonan (HGA) domains are crucial in determining its functional properties. Pectin methylesterase (PME) catalyzes the demethylesterification of HGA, which is pivotal for adjusting cell wall properties in response to environmental cues. Our investigation of PME12, a type-I pectin methylesterase in Arabidopsis, reveals its role in abscisic acid (ABA)-mediated stomatal regulation during heat stress, with the pme12 mutant showing increased stomatal density, reduced size, and heightened sensitivity to ABA-induced closure. Additionally, pme12 plants exhibited altered PME activities under heat stress but displayed enhanced thermotolerance. Moreover, our study identified SCRM as a transcriptional regulator positively influencing PME12 expression, linking stomatal development with PME12-mediated pectin methylesterification. These findings suggest that PME12-mediated pectin modification plays a role in coordinating ABA responses and influencing stomatal behavior under heat stress conditions., Competing Interests: Declarations. Conflict of interest: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Dissecting the mechanisms underlying heat tolerance is important for understanding how plants acclimate to heat stress. Here, we identify a heat-responsive gene in Arabidopsis thaliana, RNA-DIRECTED DNA METHYLATION 16 (RDM16), which encodes a pre-mRNA splicing factor. Knockout mutants of RDM16 are hypersensitive to heat stress, which is associated with impaired splicing of the mRNAs of 18 out of 20 HEAT SHOCK TRANSCRIPTION FACTOR (HSF) genes. RDM16 forms condensates upon exposure to heat. The arginine residues in intrinsically disordered region 1 (IDR1) of RDM16 are responsible for RDM16 condensation and its function in heat stress tolerance. Notably, RDM16 produces two alternatively spliced transcripts designated RDM16-LONG (RDL) and RDM16-SHORT (RDS). RDS also forms condensates and can promote RDL condensation to improve heat tolerance. Our findings provide insight into the cooperative condensation of the two RDM16 isoforms encoded by RDM16 splice variants in enhancing heat tolerance in Arabidopsis., Competing Interests: Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

The simultaneous occurrence of high temperatures and hypoxia events caused mass die-offs of aquatic animals. It is crucial to investigate the relationship between hypoxia tolerance and thermal tolerance of aquatic animals to predict the biological and ecological outcomes under global climate change scenarios. In this study, the hypoxia tolerance and thermal tolerance of Pacific abalone, Haliotis discus hannai, were measured by methods based on adhesion capacity (hypoxia adhesion duration and heat adhesion duration) and heart rate fluctuations (breakpoint of dissolved oxygen and Arrhenius breakpoint temperature). Weak correlations were found between hypoxia tolerance and thermal tolerance (Spearman correlation, r = -0.09, P = 0.2069; Pearson correlation, r = -0.04, P = 0.3313). Furthermore, a total of 21 significant SNPs and 19 candidate genes (such as cubn, lrp6, gria2, rft2, and casp8) were identified to be associated with hypoxia tolerance of Pacific abalone by conducting whole genome resequencing and genome-wide association study (GWAS). But there was no overlap between candidate genes associated with hypoxia tolerance and candidate genes associated with thermal tolerance, validating the weak correlation between hypoxia tolerance and thermal tolerance. This study highlights that individuals with greater hypoxia tolerance do not necessarily have greater thermal tolerance. Global warming and hypoxia may pose a greater threat to population size and genetic diversity of some aquatic animals than previously believed., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Calcium-dependent protein kinases (CDPKs) are very effective calcium signal decoders due to their unique structure, which mediates substrate-specific [Ca 2+ ] cyt signalling through phosphorylation. However, Ca 2+ -dependence makes it challenging to study CDPKs. This work focused on the effects of the overexpression of native and modified forms of the AtCPK1 gene on the tolerance of tobacco plants to heat and cold. We studied the interaction between the calcium and signalling systems of abscisic acid (ABA) at various temperatures. The hormonal state, stress-induced senescence, and expression of important corresponding genes were investigated. We showed that inactivation of the autoinhibitory domain of the modified constitutively active form of AtCPK1 has a positive effect on resistance not only to long-term cold but also to heat. We showed that the constitutively active form of AtCPK1 under nonstressed conditions activated biosynthesis of ABA, but a decrease in ABA content was detected upon heat exposure. On the basis of our results, we can assume that this effect is achieved through the CPK-dependent activation of salicylic acid (SA) signalling. The obtained data shed light on heat-associated molecular processes and support the possibility of using intradomain modifications of CDPK both for comprehensive study of its functional features and as a bioengineering tool., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

The growth and development of maize (Zea mays L.) are significantly impeded by prolonged exposure to high temperatures. Heat stress transcription factors (HSFs) play crucial roles in enabling plants to detect and respond to elevated temperatures. However, the genetic mechanisms underlying the responses of HSFs to heat stress in maize remain unclear. Thus, we aimed to investigate the role of ZmHSFA2B in regulating heat tolerance in maize. Here, we report that ZmHSFA2B has two splicing variants, ZmHSFA2B-I and ZmHSFA2B-II. ZmHSFA2B-I encodes full-length ZmHSFA2B (ZmHSFA2B-I), whereas ZmHSFA2B-II encodes a truncated ZmHSFA2B (ZmHSFA2B-II). Overexpression of ZmHSFA2B-I improved heat tolerance in maize and Arabidopsis thaliana, but it also resulted in growth retardation as a side effect. RNA-sequencing and CUT&Tag analyses identified ZmMBR1 as a putative target of ZmHSFA2B-I. Overexpression of ZmMBR1 also enhanced heat tolerance in Arabidopsis. ZmHSFA2B-II was primarily synthesized in response to heat stress and competitively interacted with ZmHSFA2B-I. This interaction consequently reduced the DNA-binding activities of ZmHSFA2B-I homodimers to the promoter of ZmMBR1. Subsequent investigations indicate that ZmHSFA2B-II limits the transactivation and tempers the function of ZmHSFA2B-I, thereby reducing the adverse effects of excessive ZmHSFA2B-I accumulation. Based on these observations, we propose that the alternative splicing of ZmHSFA2B generates a self-regulatory loop that fine-tunes heat stress response in maize., (© 2024 The Author(s). Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.)

Heat stress at the flowering stage significantly impacts rice grain yield, yet the number of identified genes associated with rice heat tolerance at this crucial stage remains limited. This study focuses on elucidating the function of the heat-induced gene reduced heat stress tolerance 1 (OsRHS). Overexpression of OsRHS leads to reduced heat tolerance, while RNAi silencing or knockout of OsRHS enhances heat tolerance without compromising yield, as assessed by the seed setting rate. OsRHS is localized in the cytoplasm and mainly expressed in the glume and anther of spikelet. Moreover, OsRHS was found to interact with the HSP protein cHSP70-4, and the knockout of cHSP70-4 resulted in increased heat tolerance. Complementation assays revealed that the knockout of cHSP70-4 could restore the compromised heat tolerance in OsRHS overexpression plants. Additional investigation reveals that elevated temperatures can amplify the bond between OsRHS and cHSP70-4 within rice. Furthermore, our findings indicate that under heat stress conditions during the flowering stage, OsRHS plays a negative regulatory role in the expression of many stress-related genes. These findings unveil the crucial involvement of OsRHS and cHSP70-4 in modulating heat tolerance in rice and identify novel target genes for enhancing heat resilience during the flowering phase in rice., (© 2024 John Wiley & Sons Ltd.)

Although WRKY transcription factors play crucial roles in plant responses to high-temperature stress, little is known about Group IIb WRKY family members. Here, we identified the WRKY-IIb protein PlWRKY47 from herbaceous peony (Paeonia lactiflora Pall.), which functioned as a nuclear-localized transcriptional activator. The expression level of PlWRKY47 was positively correlated with high-temperature tolerance. Silencing of PlWRKY47 in P. lactiflora resulted in the decreased tolerance to high-temperature stress by accumulating reactive oxygen species (ROS). Overexpression of PlWRKY47 improved plant high-temperature tolerance through decreasing ROS accumulation. Moreover, PlWRKY47 directly bound to the promoter of cytosolic glyceraldehyde-3-phosphate dehydrogenase 2 (PlGAPC2) gene and activated its transcription. PlGAPC2 was also positively regulated high-temperature tolerance in P. lactiflora by increasing NAD + content to inhibit ROS generation. Additionally, PlWRKY47 physically interacted with itself to form a homodimer, and PlWRKY47 could also interact with one Group IIb WRKY family member PlWRKY72 to form a heterodimer, they all promoted PlWRKY47 to bind to and activate PlGAPC2. These data support that the PlWRKY47-PlWRKY47 homodimer and PlWRKY72-PlWRKY47 heterodimer can directly activate PlGAPC2 expression to improve high-temperature tolerance by inhibiting ROS generation in P. lactiflora. These results will provide important insights into the plant high-temperature stress response by WRKY-IIb transcription factors., (© 2024 John Wiley & Sons Ltd.)

Heat shock transcription factors (Hsfs) play an important role in response to high temperatures by binding to the promoter of the heat shock protein gene to promote its expression. As an important ornamental plant, the rose often encounters heat stress during the flowering process. However, there are few studies on the Hsf family in roses ( Rosa. chinensis ). In the current study, 19 Hsf genes were identified from R. chinensis and grouped into three main subfamilies (A, B, and C) according to their structural characteristics and phylogenetic analysis. The expression patterns of RcHsf genes were detected in different tissues by quantitative real-time PCR. The RcHsf genes exhibited distinct expression patterns at high temperatures, with RcHsf17 having the highest expression level. RcHsf17 was localized in the nucleus and had transcriptional activity. The overexpression of RcHsf17 increased thermotolerance in Arabidopsis , suggesting the potential role of RcHsf17 in the regulation of the high-temperature response. In addition, RcHsf17 overexpressed in Arabidopsis could enhance the response of transgenic Arabidopsis to methyl jasmonate. Collectively, this study identified and screened RcHsfs in response to high temperatures in roses, providing new insights into the functional divergence of RcHsfs and a basis for screening new varieties of rose.

Heat stress transcription factors (HSFs) play a critical role in orchestrating cellular responses to elevated temperatures and various stress conditions. While extensively studied in model plants, the HSF gene family in Betula platyphylla remains unexplored, despite the availability of its sequenced genome. In this study, we employed bioinformatics approaches to identify 21 BpHSF genes within the Betula platyphylla genome, revealing their uneven distribution across chromosomes. These genes were categorized into three subfamilies: A, B, and C. Each was characterized by conserved protein motifs and gene structures, with notable divergence observed between subfamilies. Collinearity analysis suggested that segmental duplication events have driven the evolutionary expansion of the BpHSF gene family. Promoter region analysis identified an array of cis-acting elements linked to growth, development, hormonal regulation, and stress responses. Subcellular localization experiments confirmed the nuclear localization of BpHSFA2a , BpHSFB1a , and BpHSFC1a , consistent with in silico predictions. RNA-seq and RT-qPCR analyses revealed tissue-specific expression patterns of BpHSF genes and their dynamic responses to heat stress, with qPCR validation highlighting a significant upregulation of BpHSFA2a under high-temperature conditions. In summary, this study provided a comprehensive characterization of the HSF gene family in Betula platyphylla , laying a solid foundation for future functional studies. Particularly, BpHSFA2a emerges as a promising candidate gene for enhancing heat tolerance in Betula platyphylla , warranting further detailed investigation.

Heat interferes with multiple meiotic processes, leading to genome instability and sterility in flowering plants, including many crops. Despite its importance for food security, the mechanisms underlying heat tolerance of meiosis are poorly understood. In this study, we analyzed different meiotic processes in the Arabidopsis (Arabidopsis thaliana) accessions Col and Ler, their F1 hybrids, and the F2 offspring under heat stress (37 °C). At 37 °C, Col exhibits significantly reduced formation of double-strand breaks and completely abolished homolog pairing, synapsis, and crossover (CO) formation. Strikingly, Ler and Col/Ler hybrids exhibit normal CO formation and show mildly impacted homolog pairing and synapsis. Interestingly, only 10% to 20% of F2 offspring behave as Ler, revealing that heat tolerance of meiotic recombination in Arabidopsis is genetically controlled by several loci. Moreover, F2 offspring show defects in chromosome morphology and integrity and sister chromatid segregation, the levels of which exceed those in either inbreds or hybrids, thus implying a transgressive effect on heat tolerance of meiosis. Furthermore, correlation and cytogenetic analyses suggest that homolog pairing and synapsis have an impact on heat tolerance of chromosome morphology and stability at postrecombination stages. This study reveals natural heat resilience factors for meiosis in Arabidopsis, which have the great potential to be exploited in breeding programs., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

DNA repair systems are essential to maintain genome integrity and stability. Some obligate endosymbionts that experience long-term symbiosis with the insect hosts, however, have lost their key components for DNA repair. It is largely unexplored how the bacterial endosymbionts cope with the increased demand for mismatch repairs under heat stresses. Here, we showed that ibpA, a small heat shock protein encoded by Buchnera aphidicola , directly interacted with the cytoskeletal actin to prevent its aggregation in bacteriocytes, thus reinforcing the stability of bacteriocytes. However, the succession of 11 adenines in the promoter of ibpA is extremely prone to mismatching error, e.g., a single adenine deletion, which impairs the induction of ibpA under heat stress. Coinfection with a facultative endosymbiont Serratia symbiotica remarkably reduced the mutagenesis rate in the Buchnera genome and potentially prevented a single adenine deletion in ibpA promoter, thereby alleviating the heat vulnerability of aphid bacteriocytes. Furthermore, Serratia encoded mutH, a conserved core protein of prokaryotic DNA mismatch repair (MMR), accessed to Buchnera cells, which complemented Buchnera mutL and mutS in constituting an active MMR. Our findings imply that a full complement of a prokaryotic MMR system assembled by two bacterial endosymbionts contributes significantly to the thermostability of aphid bacteriocytes in an ibpA-dependent manner, furnishing a distinct molecular link among tripartite symbioses in shaping resilience and adaptation of their insect hosts to occupy other ecological niches., Competing Interests: Competing interests statement:The authors declare no competing interest.

The plasticity of stem cells in response to environmental change is critical for multicellular organisms. Here, we show that MYB3R-like directly activates the key plant stem-cell regulator WUSCHEL (WUS) by recruiting the methyltransferase ROOT INITIATION DEFECTIVE 2 (RID2), which functions in m7G methylation of the 5' cap of WUS mRNA to protect it from degradation. Transcriptomic and molecular analyses showed that protein-folding genes are repressed by WUS to maintain precise protein synthesis in stem cells by preventing the reuse of misfolded proteins. Interestingly, we found that upon heat stress, the MYB3R-like/RID2 module is repressed to reduce WUS transcript abundance through decapping of nascent WUS mRNA. This releases the inhibition of protein-folding capacity in stem cells and protects them from heat shock by eliminating misfolded protein aggregation. Taken together, our results reveal a strategic trade-off whereby plants reduce the accuracy of protein synthesis in exchange for the survival of stem cells at high temperatures., (Copyright © 2024 The Author. Published by Elsevier Inc. All rights reserved.)

Plutella xylostella is one of the most destructive pests for cruciferous vegetables, and is adaptability to different environmental stressors. However, we still know little about the molecular mechanisms of how P. xylostella adapt to thermal stress. Here, the comparative transcriptome analysis was conducted from the samples of control (27 °C, CK) and heat treatment (40 °C, 40 T) P. xylostella. The results showed 1253 genes were differentially expressed, with 624 and 629 genes up- and down-regulated respectively. The annotation analysis demonstrated that "Energy production and conversion", "Protein processing in endoplasmic reticulum", "Peroxisome" and "Tyrosine metabolism" pathways were significantly enriched. Additionally, we found the expression levels of heat shock protein genes (Hsps), cuticle related genes and mitochondrial genes were significantly up-regulated in 40 T insects, suggesting their vital roles in improving adaption to heat stress. Importantly, the SOD activity and MDA content of P. xylostella were both identified to be increased under high temperature stress, indicating the elevated antioxidant reactions might be involved in response to heat stress. In conclusion, the present study offered us an overview of gene expression changes after 40 °C treatments, and found some critical pathways and genes of P. xylostella might play the critical roles in resisting heat stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Heat stress affects the growth and development of Brassicaceae crops. Plant breeders aim to mitigate the effects of heat stress by selecting for heat stress tolerance, but the genes responsible for heat stress in Brassicaceae remain largely unknown. During heat stress, heat shock proteins (HSPs) function as molecular chaperones to aid in protein folding, and heat shock transcription factors (HSFs) serve as transcriptional regulators of HSP expression. We identified 5002 heat shock related genes, including HSPs and HSFs, across 32 genomes in Brassicaceae. Among these, 3347 genes were duplicated, with segmented duplication primarily contributing to their expansion. We identified 466 physical gene clusters, including 240 homogenous clusters and 226 heterogeneous clusters, shedding light on the organization of heat shock related genes. Notably, 37 genes were co-located with published thermotolerance quantitative trait loci, which supports their functional role in conferring heat stress tolerance. This study provides a comprehensive resource for the identification of functional Brassicaceae heat shock related genes, elucidates their clustering and duplication patterns and establishes the genomic foundation for future heat tolerance research. We hypothesise that genetic variants in HSP and HSF genes in certain species have potential for improving heat stress tolerance in Brassicaceae crops., Competing Interests: The authors declare there are no competing interests.

Understanding how organisms adapt to changing environments is a core focus of research in evolutionary biology. One common mechanism is adaptive introgression, which has received increasing attention as a potential route to rapid adaptation in populations struggling in the face of ecological change, particularly global climate change. However, hybridization can also result in deleterious genetic interactions that may limit the benefits of adaptive introgression. Here, we used a combination of genome-wide quantitative trait locus mapping and differential gene expression analyses between the swordtail fish species Xiphophorus malinche and X. birchmanni to study the consequences of hybridization on thermotolerance. While these two species are adapted to different thermal environments, we document a complicated architecture of thermotolerance in hybrids. We identify a region of the genome that contributes to reduced thermotolerance in individuals heterozygous for X. malinche and X. birchmanni ancestry, as well as widespread misexpression in hybrids of genes that respond to thermal stress in the parental species, particularly in the circadian clock pathway. We also show that a previously mapped hybrid incompatibility between X. malinche and X. birchmanni contributes to reduced thermotolerance in hybrids. Together, our results highlight the challenges of understanding the impact of hybridization on complex ecological traits and its potential impact on adaptive introgression., (© 2022 John Wiley & Sons Ltd.)

Red swamp crayfish (Procambarus clarkii) is an important freshwater aquaculture species in China. In the process of crayfish aquaculture, high temperature stress is common, which seriously affects its yield and quality. It is urgently recommended to improve these traits in the breed. However, the application of high-temperature tolerance genes in molecular breeding of crayfish has not been reported. In this study, transcriptome analysis was used to explore the high-temperature tolerance genes of crayfish. The results showed that genes related to energy metabolism, antioxidant, immunity and body restoration were involved in high temperature adaptation of crayfish. Based on the selected high temperature tolerance genes Heat Stress Protein 70 and Heat Stress Protein 90 (HSP70 and HSP90), the genetic variation of their open reading frames was investigated. Totally, three and four SNPs of HSP70 and HSP90, were obtained respectively. In addition, three high-temperature stress experiments were conducted on crayfish to identify favoured haplotypes. HSP70-1 and HSP90-1 are the favoured haplotypes of HSP70 and HSP90, respectively. Furthermore, a series of molecular markers were developed to identify the favoured haplotype combinations of HSP70 and HSP90. Finally, we propose a molecular breeding strategy to improve crayfish tolerance to high temperature, thereby providing a potential to increase crayfish yield. Together, this study provides a theoretical basis and molecular markers for the breeding of high-temperature tolerant crayfish., Competing Interests: Declaration of competing interest We declare that we have no conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

High nighttime temperature (HNT) is a major obstacle in rice production worldwide. It severely impacts spikelet fertility and induces grain chalk, the two undesirable factors leading to yield and quality decline in rice. Recently, major efforts have been undertaken to understand the genetic mechanisms underlying HNT tolerance. Here, we highlight phenotypic diversity and recent studies on breeding, genomics, and gene editing targeting this trait. These studies point to the challenges in the process as HNT tolerance has so far been found only in non-adapted varieties, and no known modern cultivar bred in the United States is able to withstand exposure to HNT during the reproductive stage. At the same time, identification of the tolerant genotypes enabled genomics, opened up tortuous but promising approaches for breeding, and showed a path for gene editing towards HNT tolerance. The recent advances have set a strong foundation for addressing this current and looming threat., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial or personal relations that could influence the work discussed in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The Earth is currently undergoing rapid warming cause of the accumulation in greenhouse gas emissions into the atmosphere and the consequent rise in global temperatures. High temperatures can bring the effects on rice development and growth and thereby decrease rice yield. In this study, we have identified that both JMJ713 and JMJ708 possess distinct histone demethylase activities. Specifically, JMJ713 modulates the levels of H3K36me2 while JMJ708 alters H3K9me3. Additionally, we have observed an interaction between JMJ713 and JMJ708, which collectively modify the level of H3K36me2. Furthermore, our findings demonstrate that JMJ713 plays an essential role to heat stress responses in rice (Oryza sativa). The overexpression of JMJ713 enhances heat tolerance in rice, whereas JMJ713 RNA interference rice lines exhibit increased sensitivity to heat. Further investigations revealed that overexpression of JMJ713 activated catalase (CAT) and peroxidase (POD) activities by mitigating excessive accumulation of reactive oxygen species (ROS) caused by heat stress. Interestingly, the setting rates of JMJ713 RNA interference lines decreased in comparing to wild-type, indicating that JMJ713 might play a crucial role in the rice seed development stage as well. Collectively, this study not only highlights JMJ713 is involved in heat stress responses but also provides insights into the conserved Fe(Ⅱ) and α-ketoglutarate (KG) binding residues are crucial for the demethylase activity of JMJ713, as well as JMJ713 interacts with JMJ708 to jointly regulate the levels of H3K36me2., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

High temperature can significantly affect the quality and yield of plants. However, there has been limited research investigating the thermotolerance of non-heading Chinese cabbage (NHCC). This study, identified BcWRKY23 through transcriptome analysis in NHCC with varying levels of thermotolerance. Overexpression and silencing experiments demonstrated that BcWRKY23 positively regulates the thermotolerance of NHCC by activating its own expression under short-term heat stress (HS). Additionally, BcWRKY23 was found to bind to the promoter of BcWRKY25 and activate its expression, which also enhanced thermotolerance. BcWRKY23 and BcWRKY25 enhanced the expression of HSR genes to improve thermotolerance. Furthermore, BcPAL1 was shown to be activated by BcWRKY23, while BcPAL2 was activated by both BcWRKY23 and BcWRKY25. Overexpression of BcPAL1 and BcPAL2 in NHCC significantly increased thermotolerance, accompanied by an enhancement of phenylalanine ammonia-lyase (PAL) activity. Moreover, under long-term HS, the significant accumulation of BcVQ11A was observed, and the interaction between BcVQ11A and BcWRKY23 as well as BcWRKY25 inhibited the activation of them to target genes, resulting in decreased PAL activity. This study proposes a HS response pathway involving BcVQ11A-BcWRKY23-BcWRKY25-BcPAL1/BcPAL2, providing valuable insights into the molecular mechanisms underlying thermotolerance in plants., (© 2024 John Wiley & Sons Ltd.)

High-temperature stress (HTS) affects the growth and production of vegetable crops, including eggplant (Solanum melongena L.). Jasmonic acid (JA) plays key roles in regulating resistance to biotic and abiotic stresses in plants. Nonetheless, reports on the role of JA in heat tolerance in eggplant are rare. Herein, the effects of JA on heat tolerance in eggplant and the functions of the JA biosynthetic genes SmLOX4 and SmLOX5 were analyzed. The results showed that the JA content increased under high-temperature treatment (HTT) and exogenous methyl jasmonate (MeJA) treatment reduced the damage caused by HTT to eggplant. The expression of SmLOX4 and SmLOX5 was induced by HTT and significantly positively correlated with JA biosynthesis. SmLOX4 and SmLOX5 were localized in chloroplasts. The silencing of SmLOX4 and SmLOX5 by virus-induced gene silencing suppressed the heat tolerance of eggplant, whereas the overexpression of SmLOX4 and SmLOX5 enhanced the heat tolerance of Arabidopsis thaliana. JA content and the expression of JA signaling-related genes decreased in the SmLOX4- and SmLOX5-silenced plants but increased in the OE-SmLOX4 and OE-SmLOX5 transgenic plants. These results revealed that SmLOX4 and SmLOX5 improved eggplant heat tolerance by mediating JA biosynthesis and JA signaling pathways., (© The Author(s) 2024. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.)

Catalase (CAT) plays a crucial role in plant responses to environmental stresses and maintaining redox homeostasis. However, its putative heat lability might compromise its activity and function, thus restricting plant thermotolerance. Herein, we verified Arabidopsis CAT3 was of poor thermostability that was then engineered by fusion expression in Escherichia coli . We found that our selected fusion partners, three hyperacidic mini-peptides and the short rubredoxin from hyperthermophile Pyrococcus furiosus , were commonly effectual to enhance the solubility and thermostability of CAT3 and enlarge its improvement on heat tolerance in E. coli and yeast. Most importantly, this finding was also achievable in plants. Fusion expression could magnify CAT3-mediated thermotolerance in tobacco. Under heat stress, transgenic lines expressing CAT3 fusions generally outperformed native CAT3 which in turn surpassed wild-type tobacco, in terms of seed germination, seedling survival, plant recovery growth, protection of chlorophyll and membrane lipids, elimination of H 2 O 2 , as well as mitigation of cell damage in leaves and roots. Moreover, we revealed that the introduced CAT3 or its fusions seemed solely responsible for the enhanced thermotolerance in tobacco. Prospectively, this fusion expression strategy would be applicable to other crucial plant proteins of intrinsic heat instability and thus provide an alternative biotechnological route for ameliorating plant heat tolerance.

Background: Heat stress has deleterious effects on physiological and performance traits in livestock. Within this context, using tropically adapted cattle breeds in pure herds or terminal crossbreeding schemes to explore heterosis is attractive for increasing animal production in warmer climate regions. This study aimed to identify biological processes, pathways, and potential biomarkers related to thermotolerance in Caracu, a tropically adapted beef cattle breed, by proteomic analysis of blood plasma. To achieve this goal, 61 bulls had their thermotolerance evaluated through a heat tolerance index. A subset of 14 extreme animals, including the seven most thermotolerant (HIGH group) and the seven least thermotolerant (LOW group), had their blood plasma samples used for proteomic analysis by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The differentially regulated proteins detected between HIGH and LOW groups were used to perform functional enrichment analysis and a protein-protein interaction network analysis., Results: A total of 217 proteins were detected only in the HIGH thermotolerant group and 51 only in the LOW thermotolerant group. In addition, 81 and 87 proteins had significantly higher and lower abundancies in the HIGH group, respectively. Regarding proteins with the highest absolute log-fold change values, we highlighted those encoded by DUSP5, IGFALS, ROCK2, RTN4, IRAG1, and NNT genes based on their functions. The functional enrichment analysis detected several biological processes, molecular functions, and pathways related to cellular responses to stress, immune system, complement system, and hemostasis in both HIGH and LOW groups, in addition to terms and pathways related to lipids and calcium only in the HIGH group. Protein-protein interaction (PPI) network revealed as important nodes many proteins with roles in response to stress, hemostasis, immune system, inflammation, and homeostasis. Additionally, proteins with high absolute log-fold change values and proteins detected as essential nodes by PPI analysis highlighted herein are potential biomarkers for thermotolerance, such as ADRA1A, APOA1, APOB, APOC3, C4BPA, CAT, CFB, CFH, CLU, CXADR, DNAJB1, DNAJC13, DUSP5, FGA, FGB, FGG, HBA, HBB, HP, HSPD1, IGFALS, IRAG1, KNG1, NNT, OSGIN1, PROC, PROS1, ROCK2, RTN4, RYR1, TGFB2, VLDLR, VTN, and VWF., Conclusions: Identifying potential biomarkers, molecular mechanisms and pathways that act in response to heat stress in tropically adapted beef cattle contributes to developing strategies to improve performance and welfare traits in livestock under tropical climates., Competing Interests: Declarations Ethics approval All the experimental procedures were approved by the Institutional Animal Care and Use Committee at the Animal Science Institute, Nova Odessa, São Paulo, Brazil (CEUA n°292 − 19, October 7th, 2019), following guidelines for animal welfare according to State Law No. 11.977 of the São Paulo state, Brazil. Consent for publication Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

As a plant-specific gene family, class III peroxidases (PODs) play an important role in plant growth, development, and stress responses. However, the POD gene family has not been systematically studied in Paeonia ostii . In this study, a total of 57 PoPOD genes were identified in the P. ostii genome. Subsequently, phylogenetic analysis and chromosome mapping revealed that PoPODs were classified into six subgroups and were unevenly distributed across five chromosomes. The gene structure and conserved motifs indicated the potential for functional divergence among the different subgroups. Meanwhile, four PoPODs were identified as tandem duplicated genes, with no evidence of segmental duplication. Using RNA-seq data from eight different tissues, multiple PoPODs exhibited enhanced expression in apical and adventitious roots (ARs). Next, RNA-seq data from AR development combined with trend analysis showed that PoPOD30/34/43/46/47/57 are implicated in the formation of ARs in tree peony. Through WGCNA based on RNA-seq, two key genes, PoPOD5/15 , might be involved in heat tolerance via ABA and MeJA signaling. In addition, real-time quantitative PCR (qRT-PCR) analysis indicated that PoPOD23 may play an important role in flower senescence. These findings deepened our understanding of POD-mediated AR development, heat tolerance, and petal senescence in tree peony.

Heat stress has become one of the abiotic stresses that pose an increasing threat to maize production due to global warming. The Hsp20 gene family confers tolerance to various abiotic stresses in plants. However, very few Hsp20s have been identified in relation to maize thermotolerance. In this study, we conducted a comprehensive study of Hsp20s involved in thermotolerance in maize. A total of 33 maize Hsp20 genes (ZmHsp20s) were identified through scanning for a conserved α-crystalline domain (ACD), and they were categorized into 14 subfamilies based on phylogenetic analysis. These genes are distributed across all maize chromosomes and nine of them are in regions previously identified as heat-tolerance quantitative trait loci (hrQTL). These hrQTL-associated ZmHsp20s show variation in tissue-specific expression profiles under normal conditions, and seven of them possess 1-5 heat stress elements in their promoters. The integration of RNA-seq data with real-time RT-PCR analysis indicated that ZmHsp23.4, ZmHsp22.8B and ZmHsp18 were dramatically induced under heat stress. Additionally, these genes exhibited co-expression patterns with key ZmHsfs, which are crucial in the heat tolerance pathway. When a null mutant carrying a frame-shifted ZmHsp18 gene was subjected to heat stress, its survival rate decreased significantly, indicating a critical role of ZmHsp18 in maize thermotolerance. Our study lays the groundwork for further research into the roles of ZmHsp20s in enhancing maize's thermotolerance., (© 2024. The Author(s).)

In the yeast Saccharomyces cerevisiae, 2 types of trehalase activities have been described. Neutral trehalases (Nth1 and Nth2) are considered to be the main proteins that catalyze intracellular trehalose mobilization. In addition to Nth1 and Nth2, studies have shown that acid trehalase Ath1 is required for extracellular trehalose degradation. Although both neutral and acid-type trehalases have been predominantly investigated in laboratory strains of S. cerevisiae, we sought to examine the phenotypic consequences of disrupting these genes in wild strains. In this study, we constructed mutants of the trehalose degradation pathway (NTH1, NTH2, and ATH1) in 5 diverse S. cerevisiae strains to examine whether published lab strain phenotypes are also exhibited by wild strains. For each mutant, we assessed a number of phenotypes for comparison to trehalose biosynthesis mutants, including trehalose production, glycogen production, cell size, acute thermotolerance, high-temperature growth, sporulation efficiency, and growth on a variety of carbon sources in rich and minimal medium. We found that all trehalase mutants including single deletion nth1Δ, nth2Δ, and ath1Δ, as well as double deletion nth1nth2Δ, accumulated higher intracellular trehalose levels compared to their isogenic wild-type cells. Also, nth1Δ and nth1Δnth2Δ mutants exhibited mild thermal sensitivity, suggesting a potential minor role for trehalose mobilization when cells recover from stress. In addition, we evaluated phenotypes more directly relevant to trehalose degradation, including both extracellular and intracellular trehalose utilization. We discovered that intracellular trehalose hydrolysis is critical for typical spore germination progression, highlighting a role for trehalose in cell cycle regulation, likely as a storage carbohydrate providing glycolytic fuel. Additionally, our work provides further evidence suggesting Ath1 is indispensable for extracellular trehalose utilization as a carbon source, even in the presence of AGT1., Competing Interests: Conflicts of interest The author(s) declare no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Genetics Society of America.)

Autophagy is a mechanism for the degradation of cellular components in eukaryotes and plays a critical role in plant responses to abiotic stress. As a core member of the autophagy process, ATG8's role in how plants respond to heat stress remains unclear. To investigate the response of the tomato autophagy core member ATG8f to heat stress, we studied the key gene ATG8f and generated tomato lines overexpressing SlATG8f using the recombinant expression vector pBWA(V)HS. We observed that under heat stress, SlATG8f overexpression (OE) plants exhibited decreased heat tolerance compared to wild-type (WT) plants. Specifically, OE plants showed increased relative electrolyte leakage, reduced soluble solid content, elevated chlorophyll content, and higher autophagosome numbers, with less damage to chloroplasts and mitochondria. Additionally, expression of some ATG8 family genes and heat shock protein-related genes was upregulated. Moreover, SlATG8f overexpressing plants had higher pollen vitality and more intact pollen morphology. These results suggest that while SlATG8f overexpression renders plants more sensitive to heat, it helps mitigate high-temperature damage to tomato pollen by maintaining chloroplast integrity and interacting with heat shock proteins to respond to heat stress., (© 2024. The Author(s).)

Fungi play irreplaceable roles in the functioning of natural ecosystems, but global warming poses a significant threat to them. However, the mechanisms underlying fungal tolerance to thermal and UV-B stresses remain largely unknown. Dual-specificity tyrosine phosphorylation-regulated kinase (DYRK) Pom1 is crucial for fungal growth, conidiation, and virulence. However, its role in stress tolerance within kingdom fungi has not been explored. In this study, we analyzed the function of MaPom1 (a Pom1 homologous gene) in the entomopathogenic fungus Metarhizium acridum and its regulatory roles in stress tolerance. Conidial thermal and UV-B tolerance significantly decreased in the MaPom1 disruption strain (Δ MaPom1 ), whereas conidial yield and virulence were unaffected. RNA-Seq analysis indicated that the differentially expressed genes (DEGs) were primarily related to amino sugar, nucleotide sugar metabolism, cell wall components, growth and development, and stress response pathways. Under heat shock treatment, the expression levels of heat shock protein genes decreased significantly, leading to reduced thermotolerance. Moreover, under UV-B treatment, MaPom1 expression and the enzyme activity significantly changed, indicating its involvement in regulating UV-B tolerance. The percentage of nuclear damage in Δ MaPom1 under UV-B treatment was higher than that in the wild-type strain (WT) and the complementary strain (CP). Additionally, the transcription levels of DNA damage-related genes significantly decreased, whereas those of several genes involved in the DNA damage repair response increased significantly. Overall, MaPom1 contributed to thermal and UV-B tolerance by regulating the expression of heat shock protein genes and DNA damage repair genes.

Global warming has significantly impacted agriculture, particularly in animal husbandry and aquaculture industry. Rising ocean temperatures due to global warming are severely affecting shellfish production, necessitating an understanding of how shellfish cope with thermal stress. The mitogen-activated protein kinases (MAPK) signaling pathway plays a crucial role in cell growth, differentiation, adaptation to environmental stress, inflammatory response, and managing high temperature stress. To investigate the function of MAPKs in bay scallops, a comparative genomics and bioinformatics approach identified three MAPK genes: AiERK, Aip38, and AiJNK. Structural and phylogenetic analyses of these proteins were conducted to determine their evolutionary relationships. Spatiotemporal expression patterns were examined at different developmental stages and in various tissues of healthy adult scallops. Additionally, the expression regulation of these genes was studied in selected tissues (hemocyte, gill, heart, mantle) following exposure to high temperatures (32 °C) for different durations (0 h, 6 h, 12 h, 24 h, 3 d, 6 d, 10 d). The spatiotemporal expressions of AiMAPKs were ubiquitous, with significant increases in AiERK expression observed at the umbo larval stage (3.09-fold), while Aip38 and AiJNK were identified as potential maternal effect genes. In adult scallops, different gene expression patterns of AiMAPKs were observed across eight tissues, with high expressions in the foot and gill, and lower expressions in the striated muscle. Following high temperature stress, AiMAPKs expressions in the gill and mantle were mainly up-regulated, while in the hemocyte, they were primarily down-regulated. These findings indicate time- and tissue-dependent expression patterns with functional allocation in response to different thermal durations. This study enhances our understanding of the function and evolution of AiMAPKs genes in shellfish and provides a theoretical basis for elucidating the energy regulation mechanism of bay scallops in response to high temperature stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Asian honeybees (Apis cerana) play a crucial role as pollinators to service for the ecological stability. However, their proliferation and growth are significantly impacted by environmental temperature stress. This study delves into the function of the Apis cerana vesicular inhibitory amino acid transporter gene (AcVIAAT) in safeguarding Asian honeybees against high-temperature stress. The AcVIAAT gene exhibits positive responsiveness in honeybees subjected to varying thermal conditions by triggering the genes associated with oxidative stress. Molecular docking, co-immunoprecipitation, and ELISA verify the capacity of the AcVIAAT protein to interact with γ-aminobutyric acid (GABA), a key inhibitory neurotransmitter. Administering GABA to honeybees significantly improves their survival rate under high-temperature stress and also simultaneously upregulating oxidative stress-related genes. Therefore, these findings reveal that the AcVIAAT gene enhances the thermoregulatory capacity of honeybees by modulating oxidative stress-related genes through facilitating GABA transport. The characterization of six non-synonymous SNPs in the AcVIAAT gene among A.cerana populations distributed across both the northern and southern regions indicates a potential association between gene variation and environmental adaptation. Our results contribute to elucidating the molecular mechanisms underlying high-temperature tolerance in Asian honeybees and provide a promising genetic marker for enhancing heat tolerance through genetic improvement., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Basic helix-loop-helix (bHLH) proteins comprise one of the largest families of transcription factors in plants, which play roles in plant development, secondary metabolism, and the response to biotic/abiotic stresses. However, the roles of bHLH proteins in thermotolerance are largely unknown. Herein, we identified a heat-inducible member of the bHLH family in lily (Lilium longiflorum), named LlbHLH87, which plays a role in thermotolerance. LlbHLH87 was rapidly induced by transient heat stress, and its encoded protein was localized to the nucleus, exhibiting transactivation activity in both yeast and plant cells. Overexpression of LlbHLH87 in Arabidopsis enhanced basal thermotolerance, while silencing of LlbHLH87 in lily reduced basal thermotolerance. Further analysis showed that LlbHLH87 bound to the promoters of HEAT STRESS TRANSCRIPTION FACTOR A2 (LlHSFA2) and ETHYLENE-INSENSITIVE 3 (LlEIN3) to directly activate their expression. In addition, LlbHLH87 interacted with itself and with SPATULA (LlSPT) protein. LlSPT was activated by extended heat stress and its protein competed for the homologous interaction of LlbHLH87, which reduced the transactivation ability of LlbHLH87 for target genes. Compared with that observed under LlbHLH87 overexpression alone, co-overexpression of LlbHLH87 and LlSPT reduced the basal thermotolerance of lily to sudden heat shock, but improved its thermosensitivity to prolonged heat stress treatment. Overall, our data demonstrated that LlbHLH87 regulates thermotolerance via activation of LlEIN3 and LlHSFA2, along with an antagonistic interaction with LlSPT., (© 2024 Society for Experimental Biology and John Wiley & Sons Ltd.)

Temperature sensitivity and tolerance play a key role in plant survival and production. Perennial ryegrass (Lolium perenne L.), widely cultivated in cool-season for forage supply and turfgrass, is extremely susceptible to high temperatures, therefore serving as an excellent grass for dissecting the genomic and genetic basis of high-temperature adaptation. In this study, expression analysis revealed that LpHsfA2, an important gene associated with high-temperature tolerance in perennial ryegrass, is rapidly and substantially induced under heat stress. Additionally, heat-tolerant varieties consistently display elevated expression levels of LpHsfA2 compared with heat-sensitive ones. Comparative haplotype analysis of the LpHsfA2 promoter indicated an uneven distribution of two haplotypes (HsfA2 Hap1 and HsfA2 Hap2 ) across varieties with differing heat tolerance. Specifically, the HsfA2 Hap1 allele is predominantly present in heat-tolerant varieties, while the HsfA2 Hap2 allele exhibits the opposite pattern. Overexpression of LpHsfA2 confers enhanced thermotolerance, whereas silencing of LpHsfA2 compromises heat tolerance. Furthermore, LpHsfA2 orchestrates its protective effects by directly binding to the promoters of LpHSP18.2 and LpAPX1 to activate their expression, preventing the non-specific misfolding of intracellular protein and the accumulation of reactive oxygen species in cells. Additionally, LpHsfA4 and LpHsfA5 were shown to engage directly with the promoter of LpHsfA2, upregulating its expression as well as the expression of LpHSP18.2 and LpAPX1, thus contributing to enhanced heat tolerance. Markedly, LpHsfA2 possesses autoregulatory ability by directly binding to its own promoter to modulate the self-transcription. Based on these findings, we propose a model for modulating the thermotolerance of perennial ryegrass by precisely regulating the expression of LpHsfA2. Collectively, these findings provide a scientific basis for the development of thermotolerant perennial ryegrass cultivars., (© 2024 The Author(s). Journal of Integrative Plant Biology published by John Wiley & Sons Australia, Ltd on behalf of Institute of Botany, Chinese Academy of Sciences.)

Background: High-temperature fermentation technology is promising in improving fermentation speed and product quality, and thereby widely used in various fields such as food, pharmaceuticals, and biofuels. However, extreme temperature conditions can disrupt cell membrane structures and interfere with the functionality of biological macromolecules (e.g. proteins and RNA), exerting detrimental effects on cellular viability and fermentation capability., Results: Herein, a microbial thermotolerance improvement strategy was developed based on adaptive laboratory evolution (ALE) for efficient high-temperature fermentation. Employing this strategy, we have successfully obtained Corynebacterium glutamicum strains with superior resistance to high temperatures. Specifically, the genome analysis indicated that the evolved strains harbored 13 missense genetic mutations and 3 same-sense genetic mutations compared to the non-evolved parent strain. Besides, reverse transcription quantitative PCR analysis (RT qPCR) of the hrcA-L119P mutant demonstrated that both groEL genes were upregulated under 42 °C, which enabled the construction of robust strains with improved heat tolerance. Furthermore, a significant increase in FAS-IA and FAS-IB expression of the fasR-L102F strain was proved to play a key role in protecting cells against heat stress., Conclusions: This work systematically reveals the thermotolerance mechanisms of Corynebacterium glutamicum and opens a new avenue for revolutionizing the design of cell factories to boost fermentation efficiency., (© 2024. The Author(s).)

Global warming poses a threat for crops, therefore, the identification of thermotolerance mechanisms is a priority. In plants, the core factors that regulate transcription under heat stress (HS) are well described and include several HS transcription factors (HSFs). Despite the relevance of alternative splicing in HS response and thermotolerance, the core regulators of HS-sensitive alternative splicing have not been identified. In tomato, alternative splicing of HSFA2 is important for acclimation to HS. Here, we show that several members of the serine/arginine-rich family of splicing factors (SRSFs) suppress HSFA2 intron splicing. Individual-nucleotide resolution UV cross-linking and immunoprecipitation (iCLIP) combined with RNA-Seq revealed that RS2Z35 and RS2Z36, which make up a plant-specific clade of SR proteins, not only regulate HSFA2 but approximately 50% of RNAs that undergo HS-sensitive alternative splicing, with preferential binding to purine-rich RNA motifs. Single and double CRISPR rs2z mutant lines show a dysregulation of splicing and exhibit lower basal and acquired thermotolerance compared to wild type plants. Our results suggest that RS2Z35 and RS2Z36 have a central role in mitigation of the negative effects of HS on RNA splicing homeostasis, and their emergence might have contributed to the increased capacity of plants to acclimate to high temperatures., (© The Author(s) 2024. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Clostridium perfringens type F isolates utilize C. perfringens enterotoxin (CPE) to cause food poisoning (FP) and nonfoodborne gastrointestinal diseases. The enterotoxin gene ( cpe ) can be located on either the chromosome or plasmids, but most FP isolates carry a chromosomal cpe (c -cpe ) gene. Our 2000 article in Applied and Environmental Microbiology (66:3234-3240, 2000, https://doi.org/10.1128/aem.66.8.3234-3240.2000https://doi.org/10.1128/AEM.66.8.3234-3240.2000) determined that vegetative cells and spores of c- cpe isolates are more heat resistant than those of plasmid cpe (p- cpe ) isolates, which is favorable for their survival in improperly cooked or held food. However, that 2000 article was recently retracted (90:e00249-24, 2024, https://doi.org/10.1128/aem.00249-24). To our knowledge, the 2000 article remains the only study reporting that heat resistance differences are common between both vegetative cells and spores of type F c- cpe isolates vs type F p- cpe isolates. To confirm and preserve this information in the literature, the heat resistance portion of the 2000 study has been repeated. The 2024 results reproduced the 2000 results by indicating that, relative to the surveyed type F p- cpe isolates, the vegetative cells of surveyed type F c- cpe isolates are ~2-fold more heat resistant and the spores of most surveyed c- cpe isolates are ~30-fold more heat resistant. However, consistent with several reports since our 2000 paper, one surveyed type F c- cpe isolate (which did not appreciably sporulate in 2000 but sporulated in 2024) produced spores with intermediate heat sensitivity, confirming that spores of some type F c- cpe isolates lack exceptional heat resistance.IMPORTANCE Clostridium perfringens type F food poisoning (FP), which is the second most common bacterial cause of FP, involves the production of C. perfringens enterotoxin. While the enterotoxin gene ( cpe ) can be located on either the chromosome or plasmids in type F isolates, most FP cases are caused by chromosomal cpe isolates. The current results support the conclusion that the vegetative cells and spores of type F chromosomal cpe isolates are often more heat resistant than vegetative cells and spores of type F plasmid cpe isolates. Greater heat resistance should favor the survival of the spores and vegetative cells of those chromosomal cpe isolates in temperature-abused food, which may help explain the strong association of type F chromosomal cpe strains with FP., Competing Interests: The authors declare no conflict of interest.

Marine heatwaves are becoming more frequent, widespread and severe, causing mass coral bleaching and mortality. Natural adaptation may be insufficient to keep pace with climate warming, leading to calls for selective breeding interventions to enhance the ability of corals to survive such heatwaves, i.e., their heat tolerance. However, the heritability of this trait-a prerequisite for such approaches-remains unknown. We show that selecting parent colonies for high rather than low heat tolerance increased the tolerance of adult offspring (3-4-year-olds). This result held for the response to both 1-week +3.5 °C and 1-month +2.5 °C simulated marine heatwaves. In each case, narrow-sense heritability (h 2 ) estimates are between 0.2 and 0.3, demonstrating a substantial genetic basis of heat tolerance. The phenotypic variability identified in this population could theoretically be leveraged to enhance heat tolerance by up to 1 °C-week within one generation. Concerningly, selective breeding for short-stress tolerance did not improve the ability of offspring to survive the long heat stress exposure. With no genetic correlation detected, these traits may be subject to independent genetic controls. Our finding on the heritability of coral heat tolerance indicates that selective breeding could be a viable tool to improve population resilience. Yet, the moderate levels of enhancement we found suggest that the effectiveness of such interventions also demands urgent climate action., (© 2024. The Author(s).)

Key Message: Barley reproductive fitness and efficient heat stress adaptation requires the activity of TFIIS, the elongation cofactor of RNAPII. Regulation of transcriptional machinery and its adaptive role under different stress conditions are studied extensively in the dicot model plant Arabidopsis, but our knowledge on monocot species remains elusive. TFIIS is an RNA polymerase II-associated transcription elongation cofactor. Previously, it was shown that TFIIS ensures efficient transcription elongation that is necessary for heat stress survival in A. thaliana. However, the function of TFIIS has not been analysed in monocots. In the present work, we have generated and studied independent tfIIs-crispr-mutant barley lines. We show that TFIIS is needed for reproductive development and heat stress survival in barley. The molecular basis of HS-sensitivity of tfIIs mutants is the retarded expression of heat stress protein transcripts, which leads to late accumulation of HSP chaperones, enhanced proteotoxicity and ultimately to lethality. We also show that TFIIS is transcriptionally regulated in response to heat, supporting a conserved adaptive function of these control elements for plant thermal adaptation. In sum, our results are a step forward for the better understanding of transcriptional machinery regulation in monocot crops., (© 2024. The Author(s).)

Elevated temperatures during grain filling stage, exceeding the optimal range by 3-4 °C, not only results in a substantial yield reduction in wheat by 10-50% but activates disease and insect infestation. In this research, we introduced heat-tolerant MYB36 and APX-1 gene cassettes into wheat, employing an efficient Agrobacterium mediated transformation protocol, demonstrating higher transformation efficiency. The study encompassed the assembly of MYB36 and APX-1 gene cassettes, and confirmation of gene products in Agrobacterium, followed by the transformation of the MYB36 and APX-1 genes into wheat explants. We were able to select transgenic plant with various combinations. The transgenic plants with APX-1 gene alone produced medium sized grain and spike whereas with both APX-1 and MYB36 genes expressed individually under SPS and rd29a promoter respectively showed good tolerance to heat at 32 o C at grain filling/milking stage and produced relatively bold grains. While non-transgenic plants grains were wrinkled with thin spike showing susceptibility to heat. This research contributes to the broader scientific understanding of plant stress responses and the combined effectiveness of MYB36 and APX-1 genes in crop improvement without disturbing normal nutritional values. The gene integration can serve as a valuable tool in breeding programs aimed at developing heat-tolerant wheat varieties. These findings also advance our comprehension of the functions of heat-induced genes and lay the foundation for selecting optimal candidates for in-depth functional studies of heat-responsive MYB36 and APX-1 genes in wheat., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Identifying the essential factors and underlying mechanisms regulating plant heat stress (HS) responses is crucial for mitigating the threat posed by HS on plant growth, development, distribution, and productivity. In this study, we found that the Arabidopsis (Arabidopsis thaliana) super-killer2 (ski2) dicer-like4 (dcl4) mutant, characterized by RNA processing defects and the accumulation of abundant 22-nt small interfering RNAs derived from protein-coding transcripts, displayed significantly increased expression levels of HS-responsive genes and enhanced thermotolerance. These traits primarily resulted from the suppression of SMAX1-LIKE4 (SMXL4) and SMXL5, which encode 2 putative transcriptional regulators that belong to the SMXL protein family. While smxl4 and smxl5 single mutants were similar to wild type, the smxl4 smxl5 double mutant displayed substantially heightened seedling thermotolerance. Further investigation demonstrated that SMXL4 and SMXL5 repressed the transcription of HEAT-SHOCK TRANSCRIPTION FACTOR A2 (HSFA2), encoding a master regulator of thermotolerance, independently of ethylene-response factor-associated amphiphilic repression motifs. Moreover, SMXL4 and SMXL5 interacted with HSFA1d and HSFA1e, central regulators sensing and transducing HS stimuli, and antagonistically affected their transactivation activity. In addition, HSFA2 directly bound to the SMXL4 and SMXL5 promoters, inducing their expression during recovery from HS. Collectively, our findings elucidate the role of the SMXL4/SMXL5-HSFA2 regulatory module in orchestrating plant thermotolerance under HS., Competing Interests: Conflict of interest statement. The authors declare no conflict of interests., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Elevated temperatures impair pollen performance and reproductive success, resulting in lower crop yields. The tomato (Solanum lycopersicum) anthocyanin reduced (are) mutant harbors a mutation in FLAVANONE 3-HYDROXYLASE (F3H), resulting in impaired flavonol antioxidant biosynthesis. The are mutant has reduced pollen performance and seed set relative to the VF36 parental line, phenotypes that are accentuated at elevated temperatures. Transformation of are with the wild-type F3H gene, or chemical complementation with flavonols, prevented temperature-dependent reactive oxygen species (ROS) accumulation in pollen and restored the reduced viability, germination, and tube elongation of are to VF36 levels. Overexpression of F3H in VF36 prevented temperature-driven ROS increases and impaired pollen performance, revealing that flavonol biosynthesis promotes thermotolerance. Although stigmas of are had reduced flavonol and elevated ROS levels, the growth of are pollen tubes was similarly impaired in both are and VF36 pistils. RNA-seq was performed at optimal and stress temperatures in are, VF36, and the F3H overexpression line at multiple timepoints across pollen tube elongation. The number of differentially expressed genes increased over time under elevated temperatures in all genotypes, with the greatest number in are. These findings suggest potential agricultural interventions to combat the negative effects of heat-induced ROS in pollen that lead to reproductive failure., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists.)

Histone post-translational modifications (PTMs), such as acetylation and recently identified lysine 2-hydroxyisobutyrylation (Khib), act as active epigenomic marks in plants. SANT domain-containing proteins SANT1, SANT2, SANT3, and SANT4 (SANT1/2/3/4), derived from PIF/Harbinger transposases, form a complex with HISTONE DEACETYLASE 6 (HDA6) to regulate gene expression via histone deacetylation. However, whether SANT1/2/3/4 coordinates different types of PTMs to regulate transcription and mediate responses to specific stresses in plants remains unclear. Here, in addition to modulating histone deacetylation, we found that SANT1/2/3/4 proteins acted like HDA6 or HDA9 in regulating the removal of histone Khib in Arabidopsis (Arabidopsis thaliana). Histone H3 lysine acetylation (H3KAc) and histone Khib were coordinated by SANT1/2/3/4 to regulate gene expression, with H3KAc playing a predominant role and Khib acting complementarily to H3KAc. SANT1/2/3/4 mutation significantly increased the expression of heat-inducible genes with concurrent change of H3KAc levels under normal and heat stress conditions, resulting in enhanced thermotolerance. This study revealed the critical roles of Harbinger transposon-derived SANT domain-containing proteins in transcriptional regulation by coordinating different types of histone PTMs and in the regulation of plant thermotolerance by mediating histone acetylation modification., Competing Interests: Conflict of interest statement: The authors declare no competing interests., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Wheat (Triticum aestivum L.) is an important cereal crop cultivated and consumed worldwide. Global warming-induced escalation of temperature during the seedling and grain-filling phase adversely affects productivity. To survive under elevated temperatures, most crop plants develop natural mechanisms at molecular level by activating heat shock proteins. However, other heat stress-related proteins like heat acclimatization (HA) proteins are documented in hexaploid wheat but have not been explored in detail in its diploid and tetraploid progenitors, which might help to overcome elevated temperature regimes for short periods. Our study aims to explore the potential HA genes in progenitors Triticum durum and Aegilops tauschii that perform well at higher temperatures. Seven genes were identified and phylogenetically classified into three families: K homology (KH), Chloroplast protein-enhancing stress tolerance (CEST), and heat-stress-associated 32 kDa (HSA32). Protein-protein interaction network revealed partner proteins that aid mRNA translation, protein refolding, and reactive species detoxification. Syntenic analysis displayed highly conserved relationships. RT-qPCR-based expression profiling revealed HA genes to exhibit diverse and dynamic patterns under high-temperature regimes, suggesting their critical role in providing tolerance to heat stress. The present study furnishes genetic landscape of HA genes that might help in developing climate-resilient wheat with higher acclimatization potential., (© 2024 John Wiley & Sons Ltd.)