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Heat shock transcription factors (HSFs) are crucial components in heat stress response. However, the contribution of the HSFs governing the inherent thermotolerance in Rhodomyrtus tomentosa has barely been investigated. We here compared the roles of RtHSFA9a, RtHSFA9b, and RtHSFA9c in heat stress tolerance. These three genes are the results of gene duplication events, but there exist vast variations in their amino acid sequences. They are all localized to the nucleus. Arabidopsis thaliana plants with overexpressed RtHSFA9a and RtHSFA9c outperformed the wild-type plants, while the over-accumulation of RtHSFA9b had little impact on plant thermotolerance. By transiently overexpressing RtHSFA9a, RtHSFA9b, and RtHSFA9c in R. tomentosa seedlings, the mRNA abundance of heat shock response genes, including RtHSFA2a, RtHSFA2b, RtHSP17.4, RtHSP21.8, RtHSP26.5, and RtHSP70, were upregulated. Transactivation assays confirmed that there exist regulatory divergences among these three genes, viz., RtHSFA9a has the highest transcription activity in regulating RtHSFA2a, RtHSFA2b, RtHSP21.8, and RtHSP70; RtHSFA9c can transcriptionally activate RtHSFA2b, RtHSP21.8, and RtHSP70; RtHSFA9b makes limited contributions to the accumulation of RtHSFA2b, RtHSP21.8, and RtHSP70. Our results indicate that the RtHSFA9 genes make crucial contributions to the thermal adaption of R. tomentosa by positively regulating the RtHSFA2a, RtHSFA2b, and RtHSP genes, which provides novel insights into the RtHSFA9 subfamily. [ABSTRACT FROM AUTHOR]

Abstract The heat shock response (HSR) is a universal mechanism of cellular adaptation to elevated temperatures and is regulated by heat shock transcription factor 1 (HSF1) or HSF3 in vertebrate endotherms, such as humans, mice, and chickens. We here showed that HSF1 and HSF3 from egg-laying mammals (monotremes), with a low homeothermic capacity, equally possess a potential to maximally induce the HSR, whereas either HSF1 or HSF3 from birds have this potential. Therefore, we focused on cellular adaptation to daily temperature fluctuations and found that HSF1 was required for the proliferation and survival of human cells under daily temperature fluctuations. The ectopic expression of vertebrate HSF1 proteins, but not HSF3 proteins, restored the resistance in HSF1-null cells, regardless of the induction of heat shock proteins. This function was associated with the up-regulation of specific HSF1-target genes. These results indicate the distinct role of HSF1 in adaptation to thermally fluctuating environments and suggest association of homeothermic capacity with functional diversification of vertebrate HSF genes.

The heat shock response (HSR) is a universal mechanism of cellular adaptation to elevated temperatures and is regulated by heat shock transcription factor 1 (HSF1) or HSF3 in vertebrate endotherms, such as humans, mice, and chickens. We here showed that HSF1 and HSF3 from egg-laying mammals (monotremes), with a low homeothermic capacity, equally possess a potential to maximally induce the HSR, whereas either HSF1 or HSF3 from birds have this potential. Therefore, we focused on cellular adaptation to daily temperature fluctuations and found that HSF1 was required for the proliferation and survival of human cells under daily temperature fluctuations. The ectopic expression of vertebrate HSF1 proteins, but not HSF3 proteins, restored the resistance in HSF1-null cells, regardless of the induction of heat shock proteins. This function was associated with the up-regulation of specific HSF1-target genes. These results indicate the distinct role of HSF1 in adaptation to thermally fluctuating environments and suggest association of homeothermic capacity with functional diversification of vertebrate HSF genes. [ABSTRACT FROM AUTHOR]

Key message: The heat stress transcription factor HSFA2e regulates both temperature and drought response via hormonal and secondary metabolism alterations. High temperature and drought are the primary yield-limiting environmental constraints for staple food crops. Heat shock transcription factors (HSF) terminally regulate the plant abiotic stress responses to maintain growth and development under extreme environmental conditions. HSF genes of subclass A2 predominantly express under heat stress (HS) and activate the transcriptional cascade of defense-related genes. In this study, a highly heat-inducible HSF, HvHSFA2e was constitutively expressed in barley (Hordeum vulgare L.) to investigate its role in abiotic stress response and plant development. Transgenic barley plants displayed enhanced heat and drought tolerance in terms of increased chlorophyll content, improved membrane stability, reduced lipid peroxidation, and less accumulation of ROS in comparison to wild-type (WT) plants. Transcriptome analysis revealed that HvHSFA2e positively regulates the expression of abiotic stress-related genes encoding HSFs, HSPs, and enzymatic antioxidants, contributing to improved stress tolerance in transgenic plants. The major genes of ABA biosynthesis pathway, flavonoid, and terpene metabolism were also upregulated in transgenics. Our findings show that HvHSFA2e-mediated upregulation of heat-responsive genes, modulation in ABA and flavonoid biosynthesis pathways enhance drought and heat stress tolerance. [ABSTRACT FROM AUTHOR]

Heat shock transcription factors (Hsf-s) have been considered one of the major regulatory proteins that play important roles in various biological processes during the growth and development of plants. Unfortunately, no comprehensive studies of the Hsf family in papaya (Carica papaya), a popular tropical fruit crop, have been performed, even the papaya genome assembly has been released recently. In this study, a total of 18 members of the Hsf family, namely CpHsf-s have been identified in papaya. Based on various computational tools, a systematic characterization of the CpHsf family, such as gene structure, physic-chemical features, categorization, and protein-protein interaction, has been conducted. We found that the physic-chemical properties of the CpHsf proteins were highly variable, while all proteins were hydrophilic and localized in the nucleus. Our classification indicated that the CpHsf proteins could be categorized into three groups, including HsfA, HsfB, and HsfC, and members in the same clade share similar gene structure. According to the previous RNA-Seq datasets, our re-analysis revealed that the CpHsf genes exhibited different expressions in various major organs or tissues during fruit ripening and under the ultra-low temperature stress. Taken together, our study could provide a list of candidate genes for further functional characterization towards the improvement of stress tolerance in papaya.

Drought is the most severe form of stress experienced by plants worldwide. Cucumber is a vegetable crop that requires a large amount of water throughout the growth period. In our previous study, we identified that overexpression of CsHSFA1d could improve cold tolerance and the content of endogenous jasmonic acid in cucumber seedlings. To explore the functional diversities of CsHSFA1d, we treat the transgenic plants under drought conditions. In this study, we found that the heat shock transcription factor HSFA1d (CsHSFA1d) could improve drought stress tolerance in cucumber. CsHSFA1d overexpression increased the expression levels of galactinol synthase (CsGolS3) and raffinose synthase (CsRS) genes, encoding the key enzymes for raffinose family oligosaccharide (RFO) biosynthesis. Furthermore, the lines overexpressing CsHSFA1d showed higher enzymatic activity of GolS and raffinose synthase to increase the content of RFO. Moreover, the CsHSFA1d -overexpression lines showed lower reactive oxygen species (ROS) accumulation and higher ROS-scavenging enzyme activity after drought treatment. The expressions of antioxidant genes CsPOD2, CsAPX1 and CsSOD1 were also upregulated in CsHSFA1d -overexpression lines. The expression levels of stress-responsive genes such as CsRD29A, CsLEA3 and CsP5CS1 were increased in CsHSFA1d -overexpression lines after drought treatment. We conclude that CsHSFA1d directly targets and regulates the expression of CsGolS3 and CsRS to promote the enzymatic activity and accumulation of RFO to increase the tolerance to drought stress. CsHSFA1d also improves ROS-scavenging enzyme activity and gene expression indirectly to reduce drought-induced ROS overaccumulation. This study therefore offers a new gene target to improve drought stress tolerance in cucumber and revealed the underlying mechanism by which CsHSFA1d functions in the drought stress by increasing the content of RFOs and scavenging the excessive accumulation of ROS. [ABSTRACT FROM AUTHOR]

Lily is an important cut flower worldwide and prefers cool environments. The high summer temperature in China affects the quality and quantity of cut lily–flower production. In this study, the heat stress transcription factor HsfA2 was cloned from two cultivated commercial varieties, Lilium longiflorum 'White Heaven' and Lilium oriental 'Siberia', which have different responses to heat stress. An actin-interacting protein 3 (AIP3) domain was found in LlHsfA2 of Lilium longiflorum 'White Heaven' but did not appear in LoHsfA2 of Lilium oriental 'Siberia' using prediction from the simple modular architecture research tool (SMART) website. The genes LlACTIN and LoACTIN were cloned, and their amino acid sequences were found to be the same, so they were named LACTIN. There was an interaction between LlHsfA2 and LACTIN, whereas this interaction did not occur between LoHsfA2 and LACTIN based upon the bimolecular fluorescence complementary (BiFC) experiments. The silenced plants of LlHsfA2 and LACTIN were sensitive to heat stress treatment using barley stripe mosaic virus (BSMV) induced gene silencing in 'White Heaven', and LoHsfA2 silenced plants were also sensitive in 'Siberia'. In contrast, LACTIN silenced plants in 'Siberia' were normal. The expressions of LlHsfA2 or LACTIN were reduced in the LACTIN or LlHsfA2 silenced 'White heaven' plants, whereas the expressions of LoHsfA2 or LACTIN were normal in the LACTIN or LoHsfA2 silenced 'Siberia' plants. In conclusion, the diversity of protein interactions between HsfA2 and ACTIN may affect the distinctness of the heat stress response in different lily varieties, which provides new knowledge for further study on the heat stress response in lily.

[Objective] Rice is often affected by various abiotic stresses during growth and development, which severely restricts rice yield. Heat shock transcription factors（HSFs）, as an important element of resistance to abiotic stresses in plant, can enhance plant resistance to abiotic stresses by regulating the expressions of a series of stress related genes. This study aims to investigate the function and mechanism of rice heat shock transcription factor OsHsfA2b regulating abiotic stresses, which may provide excellent gene resource and theoretical support for cultivating new rice varieties with stress resistance. [Method] We constructed OsHsfA2b-overexpressed and RNAi rice transgenic plants, then their seedlings were treated with high temperature, low temperature, drought, and high salt, respectively, and their phenotypes were observed and survival rates were counted. The detection of reactive oxygen species (ROS) deposition by DAB staining, and expression levels of antioxidant pathway related genes OsSOD and OsCAT with RT-qPCR after abiotic stress treatment, aiming to analyze the regulatory effect of OsHsfA2b on the antioxidant pathway. [Result] The rice HSF gene OsHsfA2b was induced significantly by abiotic stress conditions, such as high temperature, low temperature, drought, and high salt. Compared with the wild-type plants, OsHsfA2b-overexpressed transgenic plants significantly enhanced the resistance to abiotic stresses, as well as survival rate, and less damage. On the contrary, both resistance and survival rate of OsHsfA2b-RNAi plants to abiotic stresses decreased, and the plants were severely damaged. Moreover, the ROS deposition in OsHsfA2b-overexpressed plants decreased compared with NPB and RNAi plants under abiotic stress. Correspondingly, OsHsfA2b induced the expressions of antioxidant pathway related genes OsSOD and OsCAT, suggesting that OsHsfA2b suppressed ROS accumulation to reduce its damage caused by abiotic stress induction. [Conclusion] The above results indicate that OsHsfA2b is induced by abiotic stresses and positively regulates rice resistance to abiotic stresses through antioxidant pathways, and it is an excellent gene resource for rice stress-resistance breeding. [ABSTRACT FROM AUTHOR]

Heat shock transcription factors (HSFs) play a crucial role in regulating plant growth and response to various abiotic stresses. In this study, we conducted a comprehensive analysis of the AeHSF gene family at genome-wide level in kiwifruit (Actinidia eriantha), focusing on their functions in the response to abiotic stresses. A total of 41 AeHSF genes were identified and categorized into three primary groups, namely, HSFA, HSFB, and HSFC. Further transcriptome analysis revealed that the expression of AeHSFA2b/2c and AeHSFB1c/1d/2c/3b was strongly induced by salt, which was confirmed by qRT-PCR assays. The overexpression of AeHSFA2b in Arabidopsis significantly improved the tolerance to salt stress by increasing AtRS5, AtGolS1 and AtGolS2 expression. Furthermore, yeast one-hybrid, dual-luciferase, and electrophoretic mobility shift assays demonstrated that AeHSFA2b could bind to the AeRFS4 promoter directly. Therefore, we speculated that AeHSFA2b may activate AeRFS4 expression by directly binding its promoter to enhance the kiwifruit's tolerance to salt stress. These results will provide a new insight into the evolutionary and functional mechanisms of AeHSF genes in kiwifruit. [ABSTRACT FROM AUTHOR]

Heat shock transcription factors (HSFs) contribute significantly to thermotolerance acclimation. Here, we identified and cloned a putative HSF gene (HSFA2h) of 1218 nucleotide (acc. no. KP257297.1) from wheat cv. HD2985 using a de novo transcriptomic approach and predicted sHSP as its potential target. The expression of HSFA2h and its target gene (HSP17) was observed at the maximum level in leaf tissue under heat stress (HS), as compared to the control. The HSFA2h-pRI101 binary construct was mobilized in Arabidopsis, and further screening of T3 transgenic lines showed improved tolerance at an HS of 38 °C compared with wild type (WT). The expression of HSFA2h was observed to be 2.9- to 3.7-fold higher in different Arabidopsis transgenic lines under HS. HSFA2h and its target gene transcripts (HSP18.2 in the case of Arabidopsis) were observed to be abundant in transgenic Arabidopsis plants under HS. We observed a positive correlation between the expression of HSFA2h and HSP18.2 under HS. Evaluation of transgenic lines using different physio-biochemical traits linked with thermotolerance showed better performance of HS-treated transgenic Arabidopsis plants compared with WT. There is a need to further characterize the gene regulatory network (GRN) of HSFA2h and sHSP in order to modulate the HS tolerance of wheat and other agriculturally important crops. [ABSTRACT FROM AUTHOR]

The heat shock transcription factor (HSF) family is involved in regulating growth, development, and abiotic stress. The characteristics and biological functions of HSF family member in X. sorbifolium, an important oil and ornamental plant, have never been reported. In this study, 21 XsHSF genes were identified from the genome of X. sorbifolium and named XsHSF1-XsHSF21 based on their chromosomal positions. Those genes were divided into three groups, A, B, and C, containing 12, one, and eight genes, respectively. Among them, 20 XsHSF genes are located on 11 chromosomes. Protein structure analysis suggested that XsHSF proteins were conserved, displaying typical DNA binding domains (DBD) and oligomerization domains (OD). Moreover, HSF proteins within the same group contain specific motifs, such as motif 5 in the HSFC group. All XsHSF genes have one intron in the CDS region, except XsHSF1 which has two introns. Promoter analysis revealed that in addition to defense and stress responsiveness elements, some promoters also contained a MYB binding site and elements involved in multiple hormones responsiveness and anaerobic induction. Duplication analysis revealed that XsHSF1 and XsHSF4 genes were segmentally duplicated while XsHSF2, XsHSF9, and XsHSF13 genes might have arisen from transposition. Expression pattern analysis of leaves and roots following salt-alkali treatment using qRT-PCR indicated that five XsHSF genes were upregulated and one XsHSF gene was downregulated in leaves upon NaCl treatment suggesting these genes may play important roles in salt response. Additionally, the expression levels of most XsHSFs were decreased in leaves and roots following alkali-induced stress, indicating that those XsHSFs may function as negative regulators in alkali tolerance. MicroRNA target site prediction indicated that 16 of the XsHSF genes may be regulated by multiple microRNAs, for example XsHSF2 might be regulated by miR156, miR394, miR395, miR408, miR7129, and miR854. And miR164 may effect the mRNA levels of XsHSF3 and XsHSF17, XsHSF9 gene may be regulated by miR172. The expression trends of miR172 and miR164 in leaves and roots on salt treatments were opposite to the expression trend of XsHSF9 and XsHSF3 genes, respectively. Promoter analysis showed that XsHSFs might be involved in light and hormone responses, plant development, as well as abiotic stress responses. Our results thus provide an overview of the HSF family in X. sorbifolium and lay a foundation for future functional studies to reveal its roles in saline-alkali response. [ABSTRACT FROM AUTHOR]

Root system architecture affects the efficient uptake of water and nutrients in plants. The root growth angle, which is a critical component in determining root system architecture, is affected by root gravitropism; however, the mechanism of root gravitropism in rice remains largely unknown. In this study, we conducted a time-course transcriptome analysis of rice roots under conditions of simulated microgravity using a three-dimensional clinostat and following gravistimulation to detect candidate genes associated with the gravitropic response. We found that HEAT SHOCK PROTEIN (HSP) genes, which are involved in the regulation of auxin transport, were preferentially up-regulated during simulated microgravity conditions and rapidly down-regulated by gravistimulation. We also found that the transcription factor HEAT STRESS TRANSCRIPTION FACTOR A2s (HSFA2s) and HSFB2s, showed the similar expression patterns with the HSPs. A co-expression network analysis and an in silico motif search within the upstream regions of the co-expressed genes revealed possible transcriptional control of HSPs by HSFs. Because HSFA2s are transcriptional activators, whereas HSFB2s are transcriptional repressors, the results suggest that the gene regulatory networks governed by HSFs modulate the gravitropic response through transcriptional control of HSPs in rice roots. [ABSTRACT FROM AUTHOR]

High temperature stress is regarded as one of the significant abiotic stresses affecting the composition and distribution of natural habitats and the productivity of agriculturally significant plants worldwide. The HSF family is one of the most important transcription factors (TFs) families in plants and capable of responding rapidly to heat and other abiotic stresses. In this study, 29 AgHSFs were identified in celery and classified into three classes (A, B, and C) and 14 subgroups. The gene structures of AgHSFs in same subgroups were conserved, whereas in different classes were varied. AgHSF proteins were predicted to be involved in multiple biological processes by interacting with other proteins. Expression analysis revealed that AgHSF genes play a significant role in response to heat stress. Subsequently, AgHSFa6-1, which was significantly induced by high temperature, was selected for functional validation. AgHSFa6-1 was identified as a nuclear protein, and can upregulate the expression of certain downstream genes (HSP98.7, HSP70-1, BOB1, CPN60B, ADH2, APX1, GOLS1) in response to hightemperature treatment. Overexpression of AgHSFa6-1 in yeast and Arabidopsis displayed higher thermotolerance, both morphologically and physiologically. In response to heat stress, the transgenic plants produced considerably more proline, solute protein, antioxidant enzymes, and less MDA than wild-type (WT) plants. Overall, this study revealed that AgHSF family members perform a key role in response to high temperature, and AgHSFa6-1 acts as a positive regulator by augmenting the ROS-scavenging system to maintain membrane integrity, reducing stomatal apertures to control water loss, and upregulating the expression level of heat-stress sensitive genes to improve celery thermotolerance. [ABSTRACT FROM AUTHOR]

Heat shock transcription factor (HSF) is an important TF that performs a dominant role in plant growth, development, and stress response network. In this study, we identified a total of 30 HSF members from poplar, which are unevenly distributed on 17 chromosomes. The poplar HSF family can be divided into three subfamilies, and the members of the same subfamily share relatively conserved domains and motifs. HSF family members are acidic and hydrophilic proteins that are located in the nucleus and mainly carry out gene expansion through segmental replication. In addition, they have rich collinearity across plant species. Based on RNA-Seq analysis, we explored the expression pattern of PtHSFs under salt stress. Subsequently, we cloned the significantly upregulated PtHSF21 gene and transformed it into Populus simonii × P. nigra. Under salt stress, the transgenic poplar overexpressing PtHSF21 had a better growth state and higher reactive oxygen scavenging ability. A yeast one-hybrid experiment indicated PtHSF21 could improve salt tolerance by specifically binding to the anti-stress cis-acting element HSE. This study comprehensively profiled the fundamental information of poplar HSF family members and their responses to salt stress and specifically verified the biological function of PtHSF21, which provides clues for understanding the molecular mechanism of poplar HSF members in response to salt stress. [ABSTRACT FROM AUTHOR]

High temperature has severely affected plant growth and development, resulting in reduced production of crops worldwide, especially wheat. Alternative splicing (AS), a crucial post-transcriptional regulatory mechanism, is involved in the growth and development of eukaryotes and the adaptation to environmental changes. Previous transcriptome data suggested that heat shock transcription factor (Hsf) TaHsfA2-7 may form different transcripts by AS. However, it remains unclear whether this post-transcriptional regulatory mechanism of TaHsfA2-7 is related to thermotolerance in wheat (Triticum aestivum). Here, we identified a novel splice variant, TaHsfA2-7-AS, which was induced by high temperature and played a positive role in thermotolerance regulation in wheat. Moreover, TaHsfA2-7-AS is predicted to encode a small truncated TaHsfA2-7 isoform, retaining only part of the DNA-binding domain (DBD). TaHsfA2-7-AS is constitutively expressed in various tissues of wheat. Notably, the expression level of TaHsfA2-7-AS is significantly up-regulated by heat shock (HS) during flowering and grain-filling stages in wheat. Further studies showed that TaHsfA2-7-AS was localized in the nucleus but lacked transcriptional activation activity. Ectopic expression of TaHsfA2-7-AS in yeast exhibited improved thermotolerance. Compared to non-transgenic plants, overexpression of TaHsfA2-7-AS in Arabidopsis results in enhanced tolerance to heat stress. Simultaneously, we also found that TaHsfA1 is directly involved in the transcriptional regulation of TaHsfA2-7 and TaHsfA2-7-AS. In summary, our findings demonstrate the function of TaHsfA2-7-AS splicing variant in response to heat stress and establish a link between regulatory mechanisms of AS and the improvement of thermotolerance in wheat. [ABSTRACT FROM AUTHOR]

As worldwide warming intensifies, the average temperature of the earth continues to increase. Temperature is a key factor for the growth and development of all organisms and governs the distribution and seasonal behavior of plants. High temperatures lead to various biochemical, physiological, and morphological changes in plants and threaten plant productivity. As sessile organisms, plants are subjected to various hostile environmental factors and forced to change their cellular state and morphological architecture to successfully deal with the damage they suffer. Therefore, plants have evolved multiple strategies to cope with an abnormal rise in temperature. There are two main mechanisms by which plants respond to elevated environmental temperatures. One is the heat stress response, which is activated under extremely high temperatures; the other is the thermomorphogenesis response, which is activated under moderately elevated temperatures, below the heat-stress range. In this review, we summarize recent progress in the study of these two important heat-responsive molecular regulatory pathways mediated, respectively, by the Heat Shock Transcription Factor (HSF)–Heat Shock Protein (HSP) pathway and PHYTOCHROME INTER-ACTING FACTOR 4 (PIF4) pathways in plants and elucidate the regulatory mechanisms of the genes involved in these pathways to provide comprehensive data for researchers studying the heat response. We also discuss future perspectives in this field. [ABSTRACT FROM AUTHOR]

Heat shock transcription factors (HSFs) contribute significantly to thermotolerance acclimation. Here, we identified and cloned a putative HSF gene (HSFA2h) of 1218 nucleotide (acc. no. KP257297.1) from wheat cv. HD2985 using a de novo transcriptomic approach and predicted sHSP as its potential target. The expression of HSFA2h and its target gene (HSP17) was observed at the maximum level in leaf tissue under heat stress (HS), as compared to the control. The HSFA2h-pRI101 binary construct was mobilized in Arabidopsis, and further screening of T3 transgenic lines showed improved tolerance at an HS of 38 °C compared with wild type (WT). The expression of HSFA2h was observed to be 2.9- to 3.7-fold higher in different Arabidopsis transgenic lines under HS. HSFA2h and its target gene transcripts (HSP18.2 in the case of Arabidopsis) were observed to be abundant in transgenic Arabidopsis plants under HS. We observed a positive correlation between the expression of HSFA2h and HSP18.2 under HS. Evaluation of transgenic lines using different physio-biochemical traits linked with thermotolerance showed better performance of HS-treated transgenic Arabidopsis plants compared with WT. There is a need to further characterize the gene regulatory network (GRN) of HSFA2h and sHSP in order to modulate the HS tolerance of wheat and other agriculturally important crops.

Arbuscular mycorrhizal fungi (AMF) have important roles in enhancing drought tolerance of host plants, but it is not clear whether and how AMF increase drought tolerance in walnut (Juglans regia). We hypothesized that AMF could activate antioxidant defense systems and heat shock transcription factors (Hsfs) transcription levels to alleviate oxidative damage caused by drought. The walnut variety ‘Liaohe No. 1’ was inoculated with Diversispora spurca and exposed to well-watered (WW, 75% of the maximum soil water capacity) and drought stress (DS, 50% of the maximum soil water capacity) for 6 weeks. Plant growth, antioxidant defense systems, and expressions of five JrHsfs in leaves were studied. Such drought treatment inhibited root mycorrhizal colonization, while plant growth performance was still improved by AMF inoculation. Mycorrhizal fungal inoculation triggered the increase in soluble protein, glutathione (GSH), ascorbic acid (ASC), and total ASC contents and ascorbic peroxidase and glutathione reductase activities, along with lower hydrogen peroxide (H2O2), superoxide anion radical (O2 •− ), and malondialdehyde (MDA) levels, compared with non-inoculation under drought. Mycorrhizal plants also recorded higher peroxidase, catalase, and superoxide dismutase activities than non-mycorrhizal plants under drought. The expression of JrHsf03, JrHsf05, JrHsf20, JrHsf22, and JrHsf24 was up-regulated under WW by AMF, while the expression of JrHsf03, JrHsf22, and JrHsf24 were up-regulated only under drought by AMF. It is concluded that D. spurca induced low oxidative burst in drought-stressed walnut through activating antioxidant defense systems and part Hsfs expressions. [ABSTRACT FROM AUTHOR]

Heat shock transcription factors (Hsfs) are key regulators in plant heat stress response, and therefore, they play vital roles in signal transduction pathways in response to environmental stresses, as well as in plant growth and development. Canavalia rosea (Sw.) DC. is an extremophile halophyte with good adaptability to high temperature and salt-drought tolerance, and it can be used as a pioneer species for ecological reconstruction on tropical coral islands. To date, very little is known regarding the functions of Hsfs in the adaptation mechanisms of plant species with specialized habitats, especially in tropical leguminous halophytes. In this study, a genome-wide analysis was performed to identify all the Hsfs in C. rosea based on whole-genome sequencing information. The chromosomal location, protein domain or motif organization, and phylogenetic relationships of 28 CrHsfs were analyzed. Promoter analyses indicated that the expression levels of different CrHsfs were precisely regulated. The expression patterns also revealed clear transcriptional changes among different C. rosea tissues, indicating that the regulation of CrHsf expression varied among organs in a developmental or tissue-specific manner. Furthermore, the expression levels of most CrHsfs in response to environmental conditions or abiotic stresses also implied a possible positive regulatory role of this gene family under abiotic stresses, and suggested roles in adaptation to specialized habitats such as tropical coral islands. In addition, some CrHsfAs were cloned and their possible roles in abiotic stress tolerance were functionally characterized using a yeast expression system. The CrHsfAs significantly enhanced yeast survival under thermal and oxidative stress challenges. Our results contribute to a better understanding of the plant Hsf gene family and provide a basis for further study of CrHsf functions in environmental thermotolerance. Our results also provide valuable information on the evolutionary relationships among CrHsf genes and the functional characteristics of the gene family. These findings are beneficial for further research on the natural ecological adaptability of C. rosea to tropical environments. [ABSTRACT FROM AUTHOR]

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Heat shock transcription factors (HSFs) activate heat shock protein gene expression by binding their promoters in response to heat stress and are considered to be pivotal transcription factors in plants. Eucalyptus is a superior source of fuel and commercial wood. During its growth, high temperature or other abiotic stresses could impact its defense capability and growth. Hsf genes have been cloned and sequenced in many plants, but rarely in Eucalyptus. In this study, we used bioinformatics methods to analyze and identify Eucalyptus Hsf genes, their chromosomal localization and structure. The phylogenetic relationship and conserved domains of their encoded proteins were further analyzed. A total of 36 Hsf genes were identified and authenticated from Eucalyptus, which were scattered across 11 chromosomes. They could be classified into three classes (A, B and C). Additionally, a large number of stress-related cis-regulatory elements were identified in the upstream promoter sequence of HSF, and cis-acting element analysis indicated that the expression of EgHsf may be regulated by plant growth and development, metabolism, hormones and stress responses. The expression profiles of five representative Hsf genes, EgHsf4, EgHsf9, EgHsf13, EgHsf24 and EgHsf32, under salt and temperature stresses were examined by qRT-PCR. The results show that the expression pattern of class B genes (EgHsf4, EgHsf24 and EgHsf32) was more tolerant to abiotic stresses than that of class A genes (EgHsf9 and EgHsf13). However, the expressions of all tested Hsf genes in six tissues were at different levels. Finally, we investigated the network of interplay between genes, and the results suggest that there may be synergistic effects between different Hsf genes in response to abiotic stresses. We conclude that the Hsf gene family played an important role in the growth and developmental processes of Eucalyptus and could be vital for maintaining cell homeostasis against external stresses. This study provides basic information on the members of the Hsf gene family in Eucalyptus and lays the foundation for the functional identification of related genes and the further investigation of their biological functions in plant stress regulation. [ABSTRACT FROM AUTHOR]

Heading date is an essential agronomic trait that affects adaptability and yield in rice (Oryza sativa). HSFs (heat shock transcription factors) are a type of transcription factor that responds to environmental stress in organisms. The relationship between the heading date and HSFs has been seldom reported so far. Here, we identified a new heat shock transcription factor, named DELAYED HEADING DATE3 (DHD3), which can significantly delay the heading date by about 14 days and provide improvements of about 77% potential yield in rice. DHD3 protein is localized in the nucleus and has weak transactivation activity. DHD3 delays the heading date by significantly suppressing Hd3a and RFT1 expression under long-day (LD) and short-day (SD) conditions. Furthermore, the low-temperature condition greatly enhances the delay effect of DHD3 on the heading date (from 16.1% to more than 89.3%). We propose that DHD3 may involve the temperature-regulated signaling pathway of flowering time in rice and has the potential to improve crop yield. [ABSTRACT FROM AUTHOR]

To maintain homeostasis, cells have evolved stress-response pathways to cope with exogenous and endogenous stress factors. Diverse stresses at high doses may be detrimental, albeit low doses of stress, known as hormesis, can be beneficial. Upon exposure to stress, such as temperature rise, the conventional heat shock response (HSR) regulated by the heat shock transcription factor 1 (HSF1) facilitates refolding of misfolded proteins with the help of heat shock proteins (HSPs). However, the role and molecular mechanisms underlying the beneficial effects of HSR with other clearance processes, such as autophagy, remain poorly understood. In this study, human ARPE-19 cells, an in vitro model of retinal pigment epithelium, were treated with hormetic heat shock (HHS) and the autophagy expression profile was examined using quantitative PCR (qPCR), immunoblotting, immunoprecipitation, and immunofluorescence. We demonstrate that HHS enhances the expression of fundamental autophagy-associated genes in ARPE-19 cells through the activation of HSF1. HHS transiently increases the level of SQSTM1 and LC3B-II and activates autophagy. These findings reveal a role for autophagic HSF1-regulated functions and demonstrate the contribution of autophagy to hormesis in the HSR by improving proteostasis. [ABSTRACT FROM AUTHOR]

Heat shock transcription factors (Hsfs) are essential regulators of plant responses to abiotic stresses, growth, and development. However, all the Hsf family members have not been identified in Sorbus pohuashanensis. Therefore, the aim of this study was to identify the Hsf family members in S. pohuashanensis and examine their expression under abiotic stress conditions through the integration of gene structure, phylogenetic relationships, chromosome location, and expression patterns. Bioinformatics-based methods, identified 33 Hsfs in S. pohuashanensis. Phylogenetic analysis of Hsfs from S. pohuashanensis and other species revealed that they were more closely related to apples and white pears, followed by Populus trichocarpa , and most distantly related to Arabidopsis. Moreover, the Hsfs were clustered into three major groups: A, B, and C. Gene structure and conserved motif analysis revealed a high degree of conservation among members of the same class. Collinearity analysis revealed that segmental duplication played an essential role in increasing the size of the SpHsfs gene family in S. pohuashanensis. Additionally, several cis-acting elements associated with growth and development, hormone response, and stress were found in the promoter region of SpHsfs genes. Furthermore, expression analysis in various tissues of S. pohuashanensis showed that the genes were closely associated with heat, drought, salt stress, growth, and developmental processes. Overall, these results provide valuable information on the evolutionary relationships of the Hsf gene family. These genes stand as strong functional candidates for further studies on the resistance of S. pohuashanensis to abiotic stresses. • This is the first study that attempted to identify Hsfs genes in Sorbus pohuashanensis. • A total of 33 SpHsfs genes were identified in Sorbus pohuashanensis. • The genes stand as functional candidates for further studies on the resistance of S. pohuashanensis to abiotic stresses. [ABSTRACT FROM AUTHOR]

Abstract Background Crop quality and yield are affected by abiotic and biotic stresses, and heat shock transcription factors (Hsfs) are considered to play important roles in regulating plant tolerance under various stresses. To investigate the response of Cucurbita moschata to abiotic stress, we analyzed the genome of C. moschata. Results In this research, a total of 36 C. moschata Hsf (CmHsf) members were identified and classified into three subfamilies (I, II, and III) according to their amino acid sequence identity. The Hsfs of the same subfamily usually exhibit a similar gene structure (intron-exon distribution) and conserved domains (DNA-binding and other functional domains). Chromosome localization analysis showed that the 36 CmHsfs were unevenly distributed on 18 of the 21 chromosomes (except for Cm_Chr00, Cm_Chr08 and Cm_Chr20), among which 18 genes formed 9 duplicated gene pairs that have undergone segmental duplication events. The Ka/Ks ratio showed that the duplicated CmHsfs have mainly experienced strong purifying selection. High-level synteny was observed between C. moschata and other Cucurbitaceae species. Conclusions The expression profile of CmHsfs in the roots, stems, cotyledons and true leaves revealed that the CmHsfs exhibit tissue specificity. The analysis of cis-acting elements and quantitative real-time polymerase chain reaction (qRT-PCR) revealed that some key CmHsfs were activated by cold stress, heat stress, hormones and salicylic acid. This study lays the foundation for revealing the role of CmHsfs in resistance to various stresses, which is of great significance for the selection of stress-tolerant C. moschata.

Abstract Background Heat shock transcription factors (Hsfs) are present in majority of plants and play central roles in thermotolerance, transgenerational thermomemory, and many other stress responses. Our previous paper identified at least 82 Hsf members in a genome-wide study on wheat (Triticum aestivum L.). In this study, we analyzed the Hsf expression profiles in the advanced development stages of wheat, isolated the markedly heat-responsive gene TaHsfA2–10 (GenBank accession number MK922287), and characterized this gene and its role in thermotolerance regulation in seedlings of Arabidopsis thaliana (L. Heynh.). Results In the advanced development stages, wheat Hsf family transcription profiles exhibit different expression patterns and varying heat-responses in leaves and roots, and Hsfs are constitutively expressed to different degrees under the normal growth conditions. Overall, the majority of group A and B Hsfs are expressed in leaves while group C Hsfs are expressed at higher levels in roots. The expression of a few Hsf genes could not be detected. Heat shock (HS) caused upregulation about a quarter of genes in leaves and roots, while a number of genes were downregulated in response to HS. The highly heat-responsive gene TaHsfA2–10 was isolated through homeologous cloning. qRT-PCR revealed that TaHsfA2–10 is expressed in a wide range of tissues and organs of different development stages of wheat under the normal growth conditions. Compared to non-stress treatment, TaHsfA2–10 was highly upregulated in response to HS, H2O2, and salicylic acid (SA), and was downregulated by abscisic acid (ABA) treatment in two-leaf-old seedlings. Transient transfection of tobacco epidermal cells revealed subcellular localization of TaHsfA2–10 in the nucleus under the normal growth conditions. Phenotypic observation indicated that TaHsfA2–10 could improve both basal thermotolerance and acquired thermotolerance of transgenic Arabidopsis thaliana seedlings and rescue the thermotolerance defect of the T-DNA insertion mutant athsfa2 during HS. Compared to wild type (WT) seedlings, the TaHsfA2–10-overexpressing lines displayed both higher chlorophyll contents and higher survival rates. Yeast one-hybrid assay results revealed that TaHsfA2–10 had transactivation activity. The expression levels of thermotolerance-related AtHsps in the TaHsfA2–10 transgeinc Arabidopsis thaliana were higher than those in WT after HS. Conclusions Wheat Hsf family members exhibit diversification and specificity of transcription expression patterns in advanced development stages under the normal conditions and after HS. As a markedly responsive transcriptional factor to HS, SA and H2O2, TaHsfA2–10 involves in thermotolerance regulation of plants through binding to the HS responsive element in promoter domain of relative Hsps and upregulating the expression of Hsp genes.

[ Objective] This paper aimed to understand the biological information and function of the Heat shock transcription factor( Hsf) in apple. [ Method]36 Hsfs were retrieved from the apple genome GDH13 vl. l,confirmed by Pfam and NCBI Conserved Domain Database,and then,TBTools,ExPASy,MEME and other software were used to further analyze33 genes with complete Hsf domain. [ Result]The proteins encoded by these genes contained 189 - 530 amino acids, with molecular weights of 21 703. 71 - 58 972. 96, and isoelectric points of 4. 55 - 8. 58. The prediction of subcellular localization showed that MD00G1095900 and MD02G1171800 could be located in chloroplast/nucleus, MD05G1313700 could be located in nucleus/mitochondria,and other Hsf were localized in the nucleus. Chromosome mapping and synteny analysis showed that there was no tandem duplication of apple Hif genes, but there were segmental duplication in 16 pairs of 24 apple Hif genes. Under saline-alkali stress, the expression of most Hif genes were significantly down-regulated. Protein interaction network analysis showed that MD03 G1258300 interacts with heat shock protein, superoxide dismutase copper chaperone, protein phosphatase 2C, and sucrose unfermentable 1-associated protein kinase 'Y regulatory subunit. MD15G1283700 interacts with heat shock protein, IAA amino acid hydrolase and alkaline leucine zipper. [Conclusion] Hsfs of apple may play an important role in regulating the response to saline-alkali stress, which provides some theoretical reference for further study of biological functions of Hsfs in apple. [ABSTRACT FROM AUTHOR]

As worldwide warming intensifies, the average temperature of the earth continues to increase. Temperature is a key factor for the growth and development of all organisms and governs the distribution and seasonal behavior of plants. High temperatures lead to various biochemical, physiological, and morphological changes in plants and threaten plant productivity. As sessile organisms, plants are subjected to various hostile environmental factors and forced to change their cellular state and morphological architecture to successfully deal with the damage they suffer. Therefore, plants have evolved multiple strategies to cope with an abnormal rise in temperature. There are two main mechanisms by which plants respond to elevated environmental temperatures. One is the heat stress response, which is activated under extremely high temperatures; the other is the thermomorphogenesis response, which is activated under moderately elevated temperatures, below the heat-stress range. In this review, we summarize recent progress in the study of these two important heat-responsive molecular regulatory pathways mediated, respectively, by the Heat Shock Transcription Factor (HSF)–Heat Shock Protein (HSP) pathway and PHYTOCHROME INTER-ACTING FACTOR 4 (PIF4) pathways in plants and elucidate the regulatory mechanisms of the genes involved in these pathways to provide comprehensive data for researchers studying the heat response. We also discuss future perspectives in this field.

Heat shock transcription factor (beat sheek transcription Eacher, HSF) is an important stress regulator in plants. Many studies have shown that HSF can improve the ability of plants to adapt to stress by regulating the stress-related genes downstream of the signaling pathway, such as improving the tolerance of plants in drought and oxidative damage. The function in the post-storage. In this study, the cassava variety SC124 was used as the material, and a sphincter (SF family gene, named MISF10) was cloned from the wood layer leaf by RT-PCR technology. The results showed that: (1) The full length of the gene is 1098 p․ 365 amino acid residues, the relative molecular weight of the protein is 40.71D. The theoretical isoelectric point is 8.15. The heavy smoke location of the protein is predicted to be the nucleus of the smoke, and the protein sequence analysis results show that MISF10 has the highest similarity with Jatropha JHSF and Oak extract HHSF, Respectively, 80.31% and 0.54%. The protein sequence of the MSF10 gene is contained in the conserved domain of the IISF protein family, such as DBD.HR A Care.HBL-B Core, the common nuclear localization signal (mour healitin signal, NIS) of intake sequence, Indicating that the protein encoded by the MISF10 gene stems from the H5FC family members. It is not expressed in all tissues, and the expression is highest in leaves. estil) and light response (keepensive min) (4) The expression analysis results are also listed. Due to drought and BA treatment, I visited China. The MISF10 gene was released during the unblocked postharvest physiological changes. Please express the online results. This indicates that the MSPTO gene may be involved in ABBA-mediated postharvest physiological changes in the ABBA-mediated crown metaphor and wooden blocks. This lays the foundation for further research on its function in wood boarding and harvesting. [ABSTRACT FROM AUTHOR]

Heat stress events are major factors limiting crop productivity. During summer days, land plants must anticipate in a timely manner upcoming mild and severe temperature. They respond by accumulating protective heat-shock proteins (HSPs), conferring acquired thermotolerance. All organisms synthetize HSPs; many of which are members of the conserved chaperones families. This review describes recent advances in plant temperature sensing, signaling, and response. We highlight the pathway from heat perception by the plasma membrane through calcium channels, such as cyclic nucleotide-gated channels, to the activation of the heat-shock transcription factors (HSFs). An unclear cellular signal activates HSFs, which act as essential regulators. In particular, the HSFA subfamily can bind heat shock elements in HSP promoters and could mediate the dissociation of bound histones, leading to HSPs transcription. Although plants can modulate their transcriptome, proteome, and metabolome to protect the cellular machinery, HSP chaperones prevent, use, and revert the formation of misfolded proteins, thereby avoiding heat-induced cell death. Remarkably, the HSP20 family is mostly tightly repressed at low temperature, suggesting that a costly mechanism can become detrimental under unnecessary conditions. Here, the role of HSP20s in response to HS and their possible deleterious expression at non-HS temperatures is discussed.

A continuous increase in ambient temperature caused by global warming has been considered a worldwide threat. As sessile organisms, plants have evolved sophisticated heat shock response (HSR) to respond to elevated temperatures and other abiotic stresses, thereby minimizing damage and ensuring the protection of cellular homeostasis. In particular, for perennial trees, HSR is crucial for their long life cycle and development. HSR is a cell stress response that increases the number of chaperones including heat shock proteins (HSPs) to counter the negative effects on proteins caused by heat and other stresses. There are a large number of HSPs in plants, and their expression is directly regulated by a series of heat shock transcription factors (HSFs). Therefore, understanding the detailed molecular mechanisms of woody plants in response to extreme temperature is critical for exploring how woody species will be affected by climate changes. In this review article, we summarize the latest findings of the role of HSFs and HSPs in the HSR of woody species and discuss their regulatory networks and cross talk in HSR. In addition, strategies and programs for future research studies on the functions of HSFs and HSPs in the HSR of woody species are also proposed.

Heat shock transcription factors (HSFs) are involved in environmental stress response and plant development, such as heat stress and flowering development. According to the structural characteristics of the HSF gene family, HSF genes were classified into three major types (HSFA, HSFB, and HSFC) in plants. Using conserved domains of HSF genes, we identified 621 HSF genes among 13 cotton genomes, consisting of eight diploid and five tetraploid genomes. Phylogenetic analysis indicated that HSF genes among 13 cotton genomes were grouped into two different clusters: one cluster contained all HSF genes of HSFA and HSFC, and the other cluster contained all HSF genes of HSFB. Comparative analysis of HSF genes in Arabidopsis thaliana, Gossypium herbaceum (A1), Gossypium arboreum (A2), Gossypium raimondii (D5), and Gossypium hirsutum (AD1) genomes demonstrated that four HSF genes were inherited from a common ancestor, A0, of all existing cotton A genomes. Members of the HSF gene family in G. herbaceum (A1) genome indicated a significant loss compared with those in G. arboretum (A2) and G. hirsutum (AD1) A genomes. However, HSF genes in G. raimondii (D5) showed relative loss compared with those in G. hirsutum (AD1) D genome. Analysis of tandem duplication (TD) events of HSF genes revealed that protein-coding genes among different cotton genomes have experienced TD events, but only the two-gene tandem array was detected in Gossypium thurberi (D1) genome. The expression analysis of HSF genes in G. hirsutum (AD1) and Gossypium barbadense (AD2) genomes indicated that the expressed HSF genes were divided into two different groups, respectively, and the expressed HSF orthologous genes between the two genomes showed totally different expression patterns despite the implementation of the same abiotic stresses. This work will provide novel insights for the study of evolutionary history and expression characterization of HSF genes in different cotton genomes and a widespread application model for the study of HSF gene families in plants.

Heat stress events are major factors limiting crop productivity. During summer days, land plants must anticipate in a timely manner upcoming mild and severe temperature. They respond by accumulating protective heat-shock proteins (HSPs), conferring acquired thermotolerance. All organisms synthetize HSPs; many of which are members of the conserved chaperones families. This review describes recent advances in plant temperature sensing, signaling, and response. We highlight the pathway from heat perception by the plasma membrane through calcium channels, such as cyclic nucleotide-gated channels, to the activation of the heat-shock transcription factors (HSFs). An unclear cellular signal activates HSFs, which act as essential regulators. In particular, the HSFA subfamily can bind heat shock elements in HSP promoters and could mediate the dissociation of bound histones, leading to HSPs transcription. Although plants can modulate their transcriptome, proteome, and metabolome to protect the cellular machinery, HSP chaperones prevent, use, and revert the formation of misfolded proteins, thereby avoiding heat-induced cell death. Remarkably, the HSP20 family is mostly tightly repressed at low temperature, suggesting that a costly mechanism can become detrimental under unnecessary conditions. Here, the role of HSP20s in response to HS and their possible deleterious expression at non-HS temperatures is discussed. [ABSTRACT FROM AUTHOR]

Genome-wide characterisation and correlation analysis between gene families and environmental stresses are important for understanding the adaptive evolution of marine animals to various environments. Heat shock protein 70 (Hsp70) and heat shock transcription factor (Hsf) are two important gene families that are associated with abiotic stresses and immune responses. In this study, the evolutionary history and function of Hsp70 and Hsf family genes were investigated in Cynoglossus semilaevis through an exhaustive search of all genomic resources. In addition, their regulatory mechanisms and cooperative relationship in marine fishes were investigated in response to various degrees of salinity stress. Gene structure, motif analysis and phylogenetic trees among various organisms provide references for biological and evolutionary studies of these genes. Most Hsp70 genes were upregulated under low salinity stress, especially heat shock protein family A member 5 (hspa5), whereas hsf1 and hsf2 were downregulated. The expression profile of Hsp70 genes under low salinity stress decreased the activity of hsf1 and hsf2, suggesting that transcriptional repression of Hsf occurs when a certain level of Hsp70 is reached. These findings may improve our understanding the regulatory mechanisms between Hsp70 and Hsf gene families in response to environmental stress and provide useful resources for future studies on these gene families. [ABSTRACT FROM AUTHOR]

A continuous increase in ambient temperature caused by global warming has been considered a worldwide threat. As sessile organisms, plants have evolved sophisticated heat shock response (HSR) to respond to elevated temperatures and other abiotic stresses, thereby minimizing damage and ensuring the protection of cellular homeostasis. In particular, for perennial trees, HSR is crucial for their long life cycle and development. HSR is a cell stress response that increases the number of chaperones including heat shock proteins (HSPs) to counter the negative effects on proteins caused by heat and other stresses. There are a large number of HSPs in plants, and their expression is directly regulated by a series of heat shock transcription factors (HSFs). Therefore, understanding the detailed molecular mechanisms of woody plants in response to extreme temperature is critical for exploring how woody species will be affected by climate changes. In this review article, we summarize the latest findings of the role of HSFs and HSPs in the HSR of woody species and discuss their regulatory networks and cross talk in HSR. In addition, strategies and programs for future research studies on the functions of HSFs and HSPs in the HSR of woody species are also proposed. [ABSTRACT FROM AUTHOR]

Heat shock transcription factors (HSFs) are involved in environmental stress response and plant development, such as heat stress and flowering development. According to the structural characteristics of the HSF gene family, HSF genes were classified into three major types (HSFA, HSFB, and HSFC) in plants. Using conserved domains of HSF genes, we identified 621 HSF genes among 13 cotton genomes, consisting of eight diploid and five tetraploid genomes. Phylogenetic analysis indicated that HSF genes among 13 cotton genomes were grouped into two different clusters: one cluster contained all HSF genes of HSFA and HSFC, and the other cluster contained all HSF genes of HSFB. Comparative analysis of HSF genes in Arabidopsis thaliana , Gossypium herbaceum (A1), Gossypium arboreum (A2), Gossypium raimondii (D5), and Gossypium hirsutum (AD1) genomes demonstrated that four HSF genes were inherited from a common ancestor, A0, of all existing cotton A genomes. Members of the HSF gene family in G. herbaceum (A1) genome indicated a significant loss compared with those in G. arboretum (A2) and G. hirsutum (AD1) A genomes. However, HSF genes in G. raimondii (D5) showed relative loss compared with those in G. hirsutum (AD1) D genome. Analysis of tandem duplication (TD) events of HSF genes revealed that protein-coding genes among different cotton genomes have experienced TD events, but only the two-gene tandem array was detected in Gossypium thurberi (D1) genome. The expression analysis of HSF genes in G. hirsutum (AD1) and Gossypium barbadense (AD2) genomes indicated that the expressed HSF genes were divided into two different groups, respectively, and the expressed HSF orthologous genes between the two genomes showed totally different expression patterns despite the implementation of the same abiotic stresses. This work will provide novel insights for the study of evolutionary history and expression characterization of HSF genes in different cotton genomes and a widespread application model for the study of HSF gene families in plants. [ABSTRACT FROM AUTHOR]

Heading date is an essential agronomic trait that affects adaptability and yield in rice (Oryza sativa). HSFs (heat shock transcription factors) are a type of transcription factor that responds to environmental stress in organisms. The relationship between the heading date and HSFs has been seldom reported so far. Here, we identified a new heat shock transcription factor, named DELAYED HEADING DATE3 (DHD3), which can significantly delay the heading date by about 14 days and provide improvements of about 77% potential yield in rice. DHD3 protein is localized in the nucleus and has weak transactivation activity. DHD3 delays the heading date by significantly suppressing Hd3a and RFT1 expression under long-day (LD) and short-day (SD) conditions. Furthermore, the low-temperature condition greatly enhances the delay effect of DHD3 on the heading date (from 16.1% to more than 89.3%). We propose that DHD3 may involve the temperature-regulated signaling pathway of flowering time in rice and has the potential to improve crop yield.

In recent years, extreme weather events such as high temperature (HT) are becoming more frequent. HT has become one of the main environmental factors affecting crop growth and development. In nature, plant cells initiate corresponding tolerant mechanisms by sensing and transducing HT signals. The mitogen-activated protein kinase (MAPK) cascade is widely involved in the signal transduction of plants to various environmental stresses. MAPK-mediated HT responses have attracted more and more attention. We herein focus on the current state of knowledge of MAPK in the plant under HT stress and summarize the mechanisms of MAPK in HT response from Ca2+ signal, reactive oxygen species (ROS) signal, heat shock transcription factor and heat shock protein, antioxidant system, and the direct downstream targets of MAPK. This review encapsulates the known plant MAPK cascade and provides prospects for ongoing research on HT response. [ABSTRACT FROM AUTHOR]

White-rot fungi, especially Trametes strains, are the primary source of industrial laccases in bioenergy and bioremediation. Trametes strains express members of the laccase gene family with different physicochemical properties and expression patterns. However, the literature on the expression pattern of the laccase gene family in Trametes trogii S0301 and the response mechanism to Cu21, a key laccase inducer, in white-rot fungal strains is scarce. In the present study, we found that Cu21 could induce the mRNAs and proteins of the two alternative splicing variants of heat shock transcription factor 2 (TtHSF2). Furthermore, the overexpression of alternative splicing variants TtHSF2a and TtHSF2b-I in the homokaryotic T. trogii S0301 strain showed opposite effects on the extracellular total laccase activity, with maximum laccase activities of approximately 0.6 and 3.0 U ml21, respectively, on day 8, which are 0.4 and 2.3 times that of the wild-type strain. Similarly, TtHSF2a and TtHSF2b-I play opposite roles in the oxidation tolerance to H2O2. In addition, the direct binding of TtHSF2a to the promoter regions of the representative laccase isoenzymes (TtLac1 and TtLac13) and protein-protein interactions between TtHSF2a and TtHSF2b-I were detected. Our results demonstrate the crucial roles of TtHSF2 and its alternative splicing variants in response to Cu21. We believe that these findings will deepen our understanding of alternative splicing of heat shock transcription factors (HSFs) and their regulatory mechanism of the laccase gene family in white-rot fungi. [ABSTRACT FROM AUTHOR]

Heat shock transcription factor (HSF) is ubiquitous in the whole biological world and plays an important role in regulating growth and development and responses to environment stress. In this study, a total of 60 HSF transcription factors in Brassica juncea genome were identified and analyzed. Phylogenetic analysis showed that HSF genes were divided into three groups namely: A, B, and C, of which group A was further divided into nine subgroups (A1–A9). The analysis of gene structure and conserved motifs showed that some homologous genes are highly conserved. There was strong conservative microcollinearity among Brassica rapa, B. juncea, and Brassica oleracea, which provides a basis for studying the replication of gene families. Moreover, the results revealed that the promoter regions of BjuHSF genes were rich in cis-elements related to growth and development, hormone signal, and stress response. The prediction of protein interaction results showed that HSFs could interact with multiple transcription factors and proteins in the genome, while functional annotation revealed that BjuHSF genes were involved in many biological processes. The expression patterns of BjuHSF genes were analyzed by qPCR, and the results showed that these genes were closely linked to stress response, hormones, and development process. These results are a foundation for further analysis of the regulation mechanism of HSF gene family. [ABSTRACT FROM AUTHOR]

[Objective] Heat Shock Transcription Factor in a key regulatory factor in defense from abiotic stresses in planta. [ Method) In this reasarch, a HSF gene designated MeHSF18 was isolated from cassava leaven through RT-PCR method. The physicochemical properties, protein domain, phylogenetic tree, and expression profiles of MeHSF18 were analyzed. (Result) The full-length cDNA of MeHSF18 Was 867 hp, encoded a polypeptide of 289 amino acid residues with a predicted relative molecular mass of 31.67 kDa and an isoelectric point of 5.90. Multiple alignment showed that MeHSF18 shared a significant degree of sequence identify with other HSF proteins in Hevea brusiliensis and Jatropha curcas. The expression profile of 11 cassava tissue showed that the high expression of MeHSF18 wan in root. The transcriptome data results indicated that MeHSF18 was upregulated by drought stress and ABA treament. The expression of MeHSF18 was also induced in cassava PPD process. [Conclusion] These results suggested that MelHSF18 might be involved in ABA mediated drought stress response and participated in PPD process. [ABSTRACT FROM AUTHOR]

Background: Crop quality and yield are affected by abiotic and biotic stresses, and heat shock transcription factors (Hsfs) are considered to play important roles in regulating plant tolerance under various stresses. To investigate the response of Cucurbita moschata to abiotic stress, we analyzed the genome of C. moschata. Results: In this research, a total of 36 C. moschata Hsf (CmHsf) members were identified and classified into three subfamilies (I, II, and III) according to their amino acid sequence identity. The Hsfs of the same subfamily usually exhibit a similar gene structure (intron-exon distribution) and conserved domains (DNA-binding and other functional domains). Chromosome localization analysis showed that the 36 CmHsfs were unevenly distributed on 18 of the 21 chromosomes (except for Cm_Chr00, Cm_Chr08 and Cm_Chr20), among which 18 genes formed 9 duplicated gene pairs that have undergone segmental duplication events. The Ka/Ks ratio showed that the duplicated CmHsfs have mainly experienced strong purifying selection. High-level synteny was observed between C. moschata and other Cucurbitaceae species. Conclusions: The expression profile of CmHsfs in the roots, stems, cotyledons and true leaves revealed that the CmHsfs exhibit tissue specificity. The analysis of cis-acting elements and quantitative real-time polymerase chain reaction (qRT-PCR) revealed that some key CmHsfs were activated by cold stress, heat stress, hormones and salicylic acid. This study lays the foundation for revealing the role of CmHsfs in resistance to various stresses, which is of great significance for the selection of stress-tolerant C. moschata. [ABSTRACT FROM AUTHOR]

Background: Heat shock transcription factors (Hsfs) are present in majority of plants and play central roles in thermotolerance, transgenerational thermomemory, and many other stress responses. Our previous paper identified at least 82 Hsf members in a genome-wide study on wheat (Triticum aestivum L.). In this study, we analyzed the Hsf expression profiles in the advanced development stages of wheat, isolated the markedly heat-responsive gene TaHsfA2–10 (GenBank accession number MK922287), and characterized this gene and its role in thermotolerance regulation in seedlings of Arabidopsis thaliana (L. Heynh.). Results: In the advanced development stages, wheat Hsf family transcription profiles exhibit different expression patterns and varying heat-responses in leaves and roots, and Hsfs are constitutively expressed to different degrees under the normal growth conditions. Overall, the majority of group A and B Hsfs are expressed in leaves while group C Hsfs are expressed at higher levels in roots. The expression of a few Hsf genes could not be detected. Heat shock (HS) caused upregulation about a quarter of genes in leaves and roots, while a number of genes were downregulated in response to HS. The highly heat-responsive gene TaHsfA2–10 was isolated through homeologous cloning. qRT-PCR revealed that TaHsfA2–10 is expressed in a wide range of tissues and organs of different development stages of wheat under the normal growth conditions. Compared to non-stress treatment, TaHsfA2–10 was highly upregulated in response to HS, H2O2, and salicylic acid (SA), and was downregulated by abscisic acid (ABA) treatment in two-leaf-old seedlings. Transient transfection of tobacco epidermal cells revealed subcellular localization of TaHsfA2–10 in the nucleus under the normal growth conditions. Phenotypic observation indicated that TaHsfA2–10 could improve both basal thermotolerance and acquired thermotolerance of transgenic Arabidopsis thaliana seedlings and rescue the thermotolerance defect of the T-DNA insertion mutant athsfa2 during HS. Compared to wild type (WT) seedlings, the TaHsfA2–10-overexpressing lines displayed both higher chlorophyll contents and higher survival rates. Yeast one-hybrid assay results revealed that TaHsfA2–10 had transactivation activity. The expression levels of thermotolerance-related AtHsps in the TaHsfA2–10 transgeinc Arabidopsis thaliana were higher than those in WT after HS. Conclusions: Wheat Hsf family members exhibit diversification and specificity of transcription expression patterns in advanced development stages under the normal conditions and after HS. As a markedly responsive transcriptional factor to HS, SA and H2O2, TaHsfA2–10 involves in thermotolerance regulation of plants through binding to the HS responsive element in promoter domain of relative Hsps and upregulating the expression of Hsp genes. [ABSTRACT FROM AUTHOR]

Heat shock transcription factors (Hsfs) play multifaceted roles in plant growth, development, and responses to environmental factors. However, their involvement in seed dormancy and germination processes has remained elusive. In this study, we identified a wheat class B Hsf gene, TaHsf-7A , with higher expression in strong-dormancy varieties compared to weak-dormancy varieties during seed imbibition. Specifically, TaHsf-7A expression increased during seed dormancy establishment and subsequently declined during dormancy release. Through the identification of a 1-bp insertion (ins)/deletion (del) variation in the coding region of TaHsf-7A among wheat varieties with different dormancy levels, we developed a CAPS marker, Hsf-7A-1319, resulting in two allelic variations: Hsf-7A-1319-ins and Hsf-7A-1319-del. Notably, the allele Hsf-7A-1319-ins correlated with a reduced seed germination rate and elevated dormancy levels, while Hsf-7A-1319-del exhibited the opposite trend across 175 wheat varieties. The association of TaHsf-7A allelic status with seed dormancy and germination levels was confirmed in various genetically modified species, including Arabidopsis, rice, and wheat. Results from the dual luciferase assay demonstrated notable variations in transcriptional activity among transformants harboring distinct TaHsf-7A alleles. Furthermore, the levels of abscisic acid (ABA) and gibberellin (GA), along with the expression levels of ABA and GA biosynthesis genes, showed significant differences between transgenic rice lines carrying different alleles of TaHsf-7A. These findings represent a significant step towards a comprehensive understanding of TaHsf-7A 's involvement in the dormancy and germination processes of wheat seeds. • The class B Hsf gene TaHsf-7A is highly expressed in wheat grains. • Transgenic experiments confirmed TaHsf-7A's crucial role in seed dormancy regulation. • AtHsfB2b and TaHsf-7A have functional similarity in regulating seed dormancy. • TaHsf-7A is involved in the ABA and GA signaling pathways to regulate seed dormancy. [ABSTRACT FROM AUTHOR]

High temperatures have been regarded as one of the main factors limiting Pyropia yezoensis cultivation in recent years. Both the heat shock proteins and antioxidant enzymes genes were activated timely before heat damage to the cell. Here, the activities of different antioxidant enzymes under different conditions, including HSF inhibitor, CaM inhibitor, and HSP70 protein inhibitor were determined. Then, RNA-seq was performed using samples that had been pretreated with corresponding chemicals under high temperature conditions. The principal component analysis inferred that the shift of gene transcription patterns under high temperature conditions was closely related to HSF since the addition of QR suppressed the changes in gene transcription pattern. The hsp70 genes and antioxidant enzyme genes were categorized into three groups by the method of WGCNA. And the HSE sites were identified using plantPAN and FIMO in most genes of the categories showed relationship to HSF. Quantitative RT-PCR analysis of designated genes (FMPK >10) indicated that the expression of hsp70 and antioxidant enzyme genes in Py. yezoensis showed various transcriptional patterns, including upregulation, downregulation, and no significant changes in response to high temperature stress. The classification between qRT-PCR and WGCNA results showed a certain consistency. Considered the results above together, it was speculated that there were different HSFs regulated the expression of different genes of hsp70 and antioxidant enzymes, and HSP70 might also regulate the expression of anti-oxidase genes under the conditions of long-term stress. Additionally, transcription factors other than HSF might be involved in the high temperature stress response. The results indicated the complexity of heat stress response mechanisms in Py. yezoensis. • Upregulation of antioxidase and hsp70 transcription are effective strategies of Py. yezoensis under heat stress conditions. • PCA analysis indicated the significance of HSF in heat response in Py. yezoensis. • Diversification of HSF indicated the different expression modules for hsp70 and antioxidant enzymes genes. [ABSTRACT FROM AUTHOR]

Abstract Background Magnolia is a woody ornamental plant, which is widely used in urban landscaping. However, its lengthy juvenile period and recalcitrance to regeneration impedes functional characterization of its genes. Results We developed an efficient protoplast isolation and transient expression system for Magnolia denudata × Magnolia acuminata ‘Yellow River’. The highest yield of protoplasts was obtained from young leaves digested in 3% Cellulase R10, 0.8% Macerozyme R10, 0.04% pectinase and 0.4 M mannitol enzymolysis solution for 6 h. For transfection of protoplasts, 20% PEG4000 for 5 min was optimal. To verify the protoplast system and begin to understand heat tolerance in Magnolia, a heat shock transcription factor MdeHSF1 was cloned from ‘Yellow River’, which belongs to the HSF subfamily A and has significant homology with AtHSFA1A. Subcellular localization analysis indicated that MdeHSF1 was expressed in the cell nucleus. Furthermore, qPCR analysis of the MdeHSF1 transcript level in response to high temperature stress suggested that MdeHSF1 might be involved in regulating heat stress tolerance in ‘Yellow River’. Conclusion The described protocol provides a simple and straightforward method for isolating protoplast and exploring gene subcellular localization of MdeHSF1 in Magnolia. This expands the new research of protoplast isolation and transfection in Magnolia.

The heat shock transcription factor (HSF) binds to cis-regulatory motifs known as heat shock elements (HSEs) to mediate the transcriptional response of HSF target genes. However, the HSF–HSEs interaction is not clearly understood. Using the newly released genome reference sequence of bread wheat, we identified 39,478 HSEs (95.6% of which were non-canonical HSEs) and collapsed them into 30,604 wheat genes, accounting for 27.6% wheat genes. Using the intensively heat-responsive transcriptomes of wheat, we demonstrated that canonical HSEs have a higher propensity to induce a response in the closest downstream genes than non-canonical HSEs. However, the response magnitude induced by non-canonical HSEs was comparable to that induced by canonical HSEs. Significantly, some non-canonical HSEs that contain mismatched nucleotides at specific positions within HSEs had a larger response magnitude than that of canonical HSEs. Consistently, most of the HSEs identified in the promoter regions of heat shock proteins were non-canonical HSEs, suggesting an important role for these non-canonical HSEs. Lastly, distinct diverged biological processes were observed between genes containing different HSE types, suggesting that sequence variation in HSEs plays a key role in the evolution of heat responses and adaptation. Our results provide a new perspective to understand the regulatory network underlying heat responses.