Insights into heat response mechanisms in Clematis species: physiological analysis, expression profiles and function verification.

KEY MESSAGE: Our results provide insights into heat response mechanisms among Clematis species. Overexpressing CvHSFA2 enhanced the heat resistance of yeast and silencing NbHSFA2 reduced the heat resistance of tobacco. Clematis species are commonly grown in western and Japanese gardens. Heat stress can inhibit many physiological processes mediating plant growth and development. The mechanism regulating responses to heat has been well characterized in Arabidopsis thaliana and some crops, but not in horticultural plants, including Clematis species. In this study, we found that Clematis alpina 'Stolwijk Gold' was heat-sensitive whereas Clematis vitalba and Clematis viticella 'Polish Spirit' were heat-tolerant based on the physiological analyses in heat stress. Transcriptomic profiling identified a set of heat tolerance-related genes (HTGs). Consistent with the observed phenotype in heat stress, 41.43% of the differentially expressed HTGs between heat treatment and control were down-regulated in heat-sensitive cultivar Stolwijk Gold, but only 9.80% and 20.79% of the differentially expressed HTGs in heat resistant C. vitalba and Polish Spirit, respectively. Co-expression network, protein-protein interaction network and phylogenetic analysis revealed that the genes encoding heat shock transcription factors (HSFs) and heat shock proteins (HSPs) may played an essential role in Clematis resistance to heat stress. Two clades of heat-induced CvHSFs were further identified by phylogenetic tree, motif analysis and qRT-PCR. Ultimately, we proposed that overexpressing CvHSFA2-2 could endow yeast with high temperature resistance and silencing its homologous gene NbHSFA2 reduced the heat resistance of tobacco. This study provides first insights into the diversity of the heat response mechanisms among Clematis species.

More Than Meets the Eye: Revisiting the Roles of Heat Shock Factor 4 in Health and Diseases.

Cells encounter a myriad of endogenous and exogenous stresses that could perturb cellular physiological processes. Therefore, cells are equipped with several adaptive and stress-response machinery to overcome and survive these insults. One such machinery is the heat shock response (HSR) program that is governed by the heat shock factors (HSFs) family in response towards elevated temperature, free radicals, oxidants, and heavy metals. HSF4 is a member of this HSFs family that could exist in two predominant isoforms, either the transcriptional repressor HSFa or transcriptional activator HSF4b. HSF4 is constitutively active due to the lack of oligomerization negative regulator domain. HSF4 has been demonstrated to play roles in several physiological processes and not only limited to regulating the classical heat shock- or stress-responsive transcriptional programs. In this review, we will revisit and delineate the recent updates on HSF4 molecular properties. We also comprehensively discuss the roles of HSF4 in health and diseases, particularly in lens cell development, cataract formation, and cancer pathogenesis. Finally, we will posit the potential direction of HSF4 future research that could enhance our knowledge on HSF4 molecular networks as well as physiological and pathophysiological functions.

Genome-Wide Analysis of the Heat Shock Transcription Factor Gene Family in Brassica juncea: Structure, Evolution, and Expression Profiles.

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.

Genome-wide identification and transcript profiles of walnut heat stress transcription factor involved in abiotic stress.

BACKGROUND: Walnut (Juglans regia) is an important tree cultivated worldwide and is exposed to a series of both abiotic and biotic stress during their life-cycles. The heat stress transcription factors (HSFs) play a crucial role in plant response to various stresses by regulating the expression of stress-responsive genes. HSF genes are classified into 3 classes: HSFA, HSFB, and HSFC. HSFA gene has transcriptional activation function and is the main regulator of high temperature-induced gene expression. HSFB gene negatively regulates plant resistance to drought and NaCl. And HSFC gene may be involved in plant response to various stresses. There are some reports about the HSF family in herbaceous plants, however, there are no reports about the HSFs in walnut. RESULT: In this study, based on the complete genome sequencing of walnut, the bioinformatics method was used and 29 HSF genes were identified. These HSFs covered 18 HSFA, 9 HSFB, and 2 HSFC genes. Phylogenetic analysis of these HSF proteins along with those from Arabidopsis thaliana showed that the HSFs in the two species are closely related to each other and have different evolutionary processes. The distribution of conserved motifs and the sequence analysis of HSF genes family indicated that the members of the walnut HSFs are highly conserved. Quantitative Real-Time PCR (qRT-PCR) analysis revealed that the most of walnut HSFs were expressed in the walnut varieties of 'Qingxiang' and 'Xiangling' under high temperature (HT), high salt and drought stress, and some JrHSFs expression pattern are different between the two varieties. CONCLUSION: The complex HSF genes family from walnut was confirmed by genome-wide identification, evolutionary exploration, sequence characterization and expression analysis. This research provides useful information for future studies on the function of the HSF genes and molecular mechanism in plant stress response.

Global integrated omics expression analyses of abiotic stress signaling HSF transcription factor genes in Oryza sativa L.: An in silico approach.

Among the significant transcription factors (TFs), HSF proteins play pivotal roles in the regulation of hormonal signal transduction and different abiotic stress (AbS) responses. Hence considering its importance, global omics expression analysis of HSF candidates was performed in rice (OsHSF). The current study identified 25 HSF family members and physically plotted them against the rice genome. These proteins were systematically analyzed for their physicochemical features, organization and expression signatures. Further, heatmap of both spatio-temporal and global plant hormones revealed the developmental tissues and hormone specific expression profiling of these genes respectively. Comparative genome mapping between OsHSF players in interrelated C4 grass species revealed the chromosome level synteny. Signalome analysis revealed the protein - protein interactions of OsHSF. Expression profiling of key players in response to stresses exhibited the new involvement in combined AbS (CAbS) responses. Our results are significantly valuable to decipher their functional analysis of CAbS tolerant in rice.

Molecular characterization and protein structure prediction of heat shock transcriptional factors in goat (Capra hircus) and sheep (Ovis aries).

The heat shock factors are important as they are master regulator of heat shock response. There are only few mammalian HSFs which have been characterized, namely HSF-1, HSF-2, HSF-4 and HSF-5. The present study was aimed to clone and sequence characterize the partial open reading frames (ORFs) of HSF-2 and HSF-5 gene from cDNA isolated from testicular tissue of sheep (Macheri) and goat (Beetal). The partial ORFs of HSF-2 gene was observed to be 1627 bp in sheep and 1179 bp in goat and for HSF-5 it is 1137 bp in sheep and 1027 bp in goat. HSF-2 and HSF-5 encode a putative protein of 593 and 461 amino acid in goat and 568 and 553 amino acid in sheep, respectively. Phylogenetic analysis between the different orthologs suggested that these proteins are conserved from bovine to humans as well as in other mammals. Further, domain analyses using PredictNLS, MARCOIL and NetNES revealed that the members of HSF-2 protein orthologs contained all major domains, i.e., DNA-binding domain (DBD) and oligomerization domain (HR-A/B, and HR-C). The 3D structure of sheep and goat HSF-2 protein was predicted using SWISS-MODEL, which showed similar confirmation with the human HSF-2 protein sequence showing functional similarity between them.

Genome-wide investigation of the heat shock transcription factor (Hsf) gene family in Tartary buckwheat (Fagopyrum tataricum).

BACKGROUND: Heat shock transcription factor (Hsfs) is widely found in eukaryotes and prokaryotes. Hsfs can not only help organisms resist high temperature, but also participate in the regulation of plant growth and development (such as involved in the regulation of seed maturity and affects the root length of plants). The Hsf gene was first isolated from yeast and then gradually found in plants and sequenced, such as Arabidopsis thaliana, rice, maize. Tartary buckwheat is a rutin-rich crop, and its nutritional value and medicinal value are receiving more and more attention. However, there are few studies on the Hsf genes in Tartary buckwheat. With the whole genome sequence of Tartary buckwheat, we can effectively study the Hsf gene family in Tartary buckwheat. RESULTS: According to the study, 29 Hsf genes of Tartary buckwheat (FtHsf) were identified and renamed according to location of FtHsf genes on chromosome after removing a redundant gene. Therefore, only 29 FtHsf genes truly had the functional characteristics of the FtHsf family. The 29 FtHsf genes were located on 8 chromosomes of Tartary buckwheat, and we found gene duplication events in the FtHsf gene family, which may promote the expansion of the FtHsf gene family. Then, the motif compositions and the evolutionary relationship of FtHsf proteins and the gene structures, cis-acting elements in the promoter, synteny analysis of FtHsf genes were discussed in detail. What's more, we found that the transcription levels of FtHsf in different tissues and fruit development stages were significantly different by quantitative real-time PCR (qRT-PCR), implied that FtHsf may differ in function. CONCLUSIONS: In this study, only 29 Hsf genes were identified in Tartary buckwheat. Meanwhile, we also classified the FtHsf genes, and studied their structure, evolutionary relationship and the expression pattern. This series of studies has certain reference value for the study of the specific functional characteristics of Tartary buckwheat Hsf genes and to improve the yield and quality of Tartary buckwheat in the future.

Genome-wide identification and abiotic stress-responsive pattern of heat shock transcription factor family in Triticum aestivum L.

BACKGROUND: Enhancement of crop productivity under various abiotic stresses is a major objective of agronomic research. Wheat (Triticum aestivum L.) as one of the world's staple crops is highly sensitive to heat stress, which can adversely affect both yield and quality. Plant heat shock factors (Hsfs) play a crucial role in abiotic and biotic stress response and conferring stress tolerance. Thus, multifunctional Hsfs may be potentially targets in generating novel strains that have the ability to survive environments that feature a combination of stresses. RESULT: In this study, using the released genome sequence of wheat and the novel Hsf protein HMM (Hidden Markov Model) model constructed with the Hsf protein sequence of model monocot (Oryza sativa) and dicot (Arabidopsis thaliana) plants, genome-wide TaHsfs identification was performed. Eighty-two non-redundant and full-length TaHsfs were randomly located on 21 chromosomes. The structural characteristics and phylogenetic analysis with Arabidopsis thaliana, Oryza sativa and Zea mays were used to classify these genes into three major classes and further into 13 subclasses. A novel subclass, TaHsfC3 was found which had not been documented in wheat or other plants, and did not show any orthologous genes in A. thaliana, O. sativa, or Z. mays Hsf families. The observation of a high proportion of homeologous TaHsf gene groups suggests that the allopolyploid process, which occurred after the fusion of genomes, contributed to the expansion of the TaHsf family. Furthermore, TaHsfs expression profiling by RNA-seq revealed that the TaHsfs could be responsive not only to abiotic stresses but also to phytohormones. Additionally, the TaHsf family genes exhibited class-, subclass- and organ-specific expression patterns in response to various treatments. CONCLUSIONS: A comprehensive analysis of Hsf genes was performed in wheat, which is useful for better understanding one of the most complex Hsf gene families. Variations in the expression patterns under different abiotic stress and phytohormone treatments provide clues for further analysis of the TaHsfs functions and corresponding signal transduction pathways in wheat.