Heat Shock Transcription Factor Genes Research Articles

Heat shock responsive genes in Brassicaceae: genome-wide identification, phylogeny, and evolutionary associations within and between genera.

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.

Heat-stress-responsive HvHSFA2e gene regulates the heat and drought tolerance in barley through modulation of phytohormone and secondary metabolic pathways.

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.

The MdHSC70-MdWRKY75 module mediates basal apple thermotolerance by regulating the expression of heat shock factor genes.

Heat stress severely restricts the growth and fruit development of apple (Malus domestica). Little is known about the involvement of WRKY proteins in the heat tolerance mechanism in apple. In this study, we found that the apple transcription factor (TF) MdWRKY75 responds to heat and positively regulates basal thermotolerance. Apple plants that overexpressed MdWRKY75 were more tolerant to heat stress while silencing MdWRKY75 caused the opposite phenotype. RNA-seq and reverse transcription quantitative PCR showed that heat shock factor genes (MdHsfs) could be the potential targets of MdWRKY75. Electrophoretic mobility shift, yeast one-hybrid, β-glucuronidase, and dual-luciferase assays showed that MdWRKY75 can bind to the promoters of MdHsf4, MdHsfB2a, and MdHsfA1d and activate their expression. Apple plants that overexpressed MdHsf4, MdHsfB2a, and MdHsfA1d exhibited heat tolerance and rescued the heat-sensitive phenotype of MdWRKY75-Ri3. In addition, apple heat shock cognate 70 (MdHSC70) interacts with MdWRKY75, as shown by yeast two-hybrid, split luciferase, bimolecular fluorescence complementation, and pull-down assays. MdHSC70 acts as a negative regulator of the heat stress response. Apple plants that overexpressed MdHSC70 were sensitive to heat, while virus-induced gene silencing of MdHSC70 enhanced heat tolerance. Additional research showed that MdHSC70 exhibits heat sensitivity by interacting with MdWRKY75 and inhibiting MdHsfs expression. In summary, we proposed a mechanism for the response of apple to heat that is mediated by the "MdHSC70/MdWRKY75-MdHsfs" molecular module, which enhances our understanding of apple thermotolerance regulated by WRKY TFs.

Overexpression of acdS in petunia reduces ethylene production and improves tolerance to heat stress.

Petunia hybrida, widely grown as a bedding plant, has reduced growth and flower quality at temperatures above 30 °C (heat stress), primarily due to heat stress-induced ethylene (ET) production. The gene acdS encodes the 1-aminocyclopropane-1-carboxylate (ACC) deaminase (ACCD) enzyme, which is known for its role in reducing ET production by breaking down the ET precursor, ACC, in plant tissues. This study investigated the impact of heat stress on both 'Mirage Rose' WT petunia and its acdS-overexpressing transgenic lines. Heat stress-induced growth inhibition was observed in WT plants but not in transgenic plants. The increased stress tolerance of transgenic plants over WT plants was associated with lower ET production, ROS accumulation, higher SPAD values, water content, and relative water content. Furthermore, higher sensitivity of the WT to heat stress than the transgenic plants was confirmed by analysing ET signalling genes, heat shock transcription factor genes, and antioxidant- and proline-related genes, more strongly induced in WT than in transgenic plants. Overall, this study suggests the potential application of acdS overexpression in other floriculture plants as a viable strategy for developing heat stress-tolerant varieties. This approach holds promise for advancing the floricultural industry by overcoming challenges related to heat-induced growth inhibition and loss of flower quality.

Genome-wide characterization and functional analysis of heat shock transcription factors in wild and cultivated rice (Oryza sativa L.)

Due to domestication, the genetic diversity in cultivated rice is lower than that of wild rice species. Recent progress in sequencing the genomes of wild and cultivated rice genus is an important step in identifying their genetic differences associated with abiotic and biotic stresses-resistant ability. Thus, in this study, heat shock transcription factor (Hsf) genes in 6 wild rice accessions, including Oryza barthii, Oryza glumaepatula, Oryza meridionalis, Oryza nivara, Oryza punctate and Oryza rufipogon, and 1 cultivated rice variety Nipponbare were firstly identified, and the evolution of rice Hsf genes were analyzed. Totally, 22, 23, 24, 24, 25, 25 and 25 Hsf genes were identified in the 7 tested rice genomes, Oryza barthii, Oryza glumaepatula, Oryza meridionalis, Oryza nivara, Oryza punctate, Oryza rufipogon and Oryza sativa, respectively. The evolutionary analysis of Hsf genes revealed that Oryza rufipogon was the immediate ancestral progenitor of Oryza sativa. The variation in the number of Hsf genes between wild and cultivated rice genotypes was mainly due to segmental duplication and whole genome duplication (WGD) events, which might contribute to the different stress-tolerant ability between the wild and cultivated rice varieties. Secondly, the function of the Hsf genes in wild and cultivated rice in response to salinity stress was compared. Under salt stress, four Hsf genes, HsfA2b, HsfB4b, HsfB4c and HsfB4d, were exclusively down-regulated in Oryza rufipogon shoots. Whilst, another four Hsf genes, HsfA7a, HsfB2c, HsfC1b and HsfC2b, were up-regulated in the shoots of both the cultivated rice and its ancestral progenitor Oryza rufipogon. Meanwhile, genomic comparison results showed that 1, 1, 5 and 5 nsSNPs were detected in these 4 Hsf genes respectively, which might alter the functions of these genes. RT-qPCR results further confirmed the expression profile of one of these 4 Hsf genes, HsfB2c. The expression pattern of this gene in the cultivated rice variety in response to salt stress was similar with the previously known salt stress-tolerant gene, WRKY28. This indicated that these 4 Hsf genes might be among the conserved genes related to salt stress tolerance in the wild and cultivated rice. In summary, these results provide novel clues to the further functional studies of Hsf genes in rice for breeding programs.

A wheat heat shock transcription factor gene, TaHsf-7A, regulates seed dormancy and germination

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.

Characterization of the Heat Shock Transcription Factor Family in Lycoris radiata and Its Potential Roles in Response to Abiotic Stresses.

Heat shock transcription factors (HSFs) are an essential plant-specific transcription factor family that regulates the developmental and growth stages of plants, their signal transduction, and their response to different abiotic and biotic stresses. The HSF gene family has been characterized and systematically observed in various species; however, research on its association with Lycoris radiata is limited. This study identified 22 HSF genes (LrHSFs) in the transcriptome-sequencing data of L. radiata and categorized them into three classes including HSFA, HSFB, and HSFC, comprising 10, 8, and 4 genes, respectively. This research comprises basic bioinformatics analyses, such as protein sequence length, molecular weight, and the identification of its conserved motifs. According to the subcellular localization assessment, most LrHSFs were present in the nucleus. Furthermore, the LrHSF gene expression in various tissues, flower developmental stages, two hormones stress, and under four different abiotic stresses were characterized. The data indicated that LrHSF genes, especially LrHSF5, were essentially involved in L. radiata development and its response to different abiotic and hormone stresses. The gene-gene interaction network analysis revealed the presence of synergistic effects between various LrHSF genes' responses against abiotic stresses. In conclusion, these results provided crucial data for further functional analyses of LrHSF genes, which could help successful molecular breeding in L. radiata.

Molecular characterization of a novel heat shock transcription factor gene TaHsfA2-11 and its overexpression improves thermotolerance in wheat

High temperature is a major constrait limiting the yield and quality of wheat. Wheat heat shock transcription factor (Hsf) plays important roles in regulating plant response to heat shock. In previous study, we found there are 82 Hsfs in wheat and TaHsfA2–11 expression was obviously upregulated by heat stress. In this study, we aim to investigate TaHsfA2–11 function and regulating mechanism in response to heat shock through genetic transformation into wheat Fielder. Gene expression analyses results showed that TaHsfA2–11 was expressed in all detected tissues and the most highly expressed level was in wheat mature roots. The expression level of TaHsfA2–11 was strongly upregulated by heat shock in wheat leaves. Subcellular localization results represented that TaHsfA2–11 is located to the nucleus. Transgenic wheat seedlings overexpressing TaHsfA2–11 showed stronger thermotolerance than the control Fielder after treated under 50 °C for 12 h. After heat shock, the TaHsfA2–11 overexpressing lines showed increased survival rate, chlorophyll content, POD (Peroxidase) activity, SOD (Superoxide dismutase) activity and photosynthetic rate, and decreased relative electrolyte leakage and MDA (malondialdehyde) content compared with Fielder. The results of RNA-sequence data demonstrated that TaHsfA2–11 can regulate many heat response genes, such as Hsp genes TaHsp16.6 and TaHsp21, ER (Endoplasmic reticulum) stress genes TaBiP2 and TaERDJ3A, photoprotectant for PSII gene TaELIPHV58, flavone biosynthesis related genes TaUGT-2A and TaPMaT, etc after heat stress. These results showed that TaHsfA2–11 can impove thermotolerance perhaps through effecting signal pathway of heat, ER stress, photosynthesis and ROS (Reactive Oxygen Species). The findings will provide useful gene resource for performing genetic modification of wheat thermotolerance in heat-resistant breeding.

Genome-Wide Identification of HSF Gene Family in Kiwifruit and the Function of AeHSFA2b in Salt Tolerance.

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.

Transcriptional Regulation of Small Heat Shock Protein 17 (sHSP-17) by Triticum aestivum HSFA2h Transcription Factor Confers Tolerance in Arabidopsis under Heat Stress.

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.

Populus trichocarpa PtHSFA4a Enhances Heat Tolerance by Regulating Expression of APX1 and HSPs

Heat stress can severely inhibit plant growth and reproduction, resulting in heavy financial and crop yield losses. Heat shock transcription factors (HSFs) play an important role in regulating plant responses to abiotic stress. However, compared with the in-depth study of HSF gene function in herbaceous species, reports on the regulatory mechanism of the response of HSFs to heat stress in trees are scarce. Here, we demonstrated that PtHSFA4a is induced by high temperatures in Populus trichocarpa leaves. Intense GUS activity was detected in the leaves of PtHSFA4a promoter-GUS reporter transgenic line under heat stress. Ectopic expression of PtHSFA4a in Arabidopsis thaliana enhanced heat stress tolerance, which reduced malondialdehyde and reactive oxygen species levels. RT-qPCR revealed that the expression of key heat stress-related genes (that is, AtMBF1c, AtZAT12, AtAPX1, AtHSA32, and AtHSPs) was upregulated in PtHSFA4a transgenic plants. Additionally, PtHSFA4a directly bind to the promoters of AtAPX1 and AtHSPs under heat stress to enhance heat tolerance by upregulating the antioxidant defense system and maintaining protein folding homeostasis in A. thaliana leaves. These findings provide novel insights into the molecular mechanisms underlying PtHSFA4a-mediated regulation of plant responses to heat stress.

Genome-wide identification of the heat shock transcription factor gene family in two kiwifruit species.

High temperatures have a significant impact on plant growth and metabolism. In recent years, the fruit industry has faced a serious threat due to high-temperature stress on fruit plants caused by global warming. In the present study, we explored the molecular regulatory mechanisms that contribute to high-temperature tolerance in kiwifruit. A total of 36 Hsf genes were identified in the A. chinensis (Ac) genome, while 41 Hsf genes were found in the A. eriantha (Ae) genome. Phylogenetic analysis revealed the clustering of kiwifruit Hsfs into three distinct groups (groups A, B, and C). Synteny analysis indicated that the expansion of the Hsf gene family in the Ac and Ae genomes was primarily driven by whole genome duplication (WGD). Analysis of the gene expression profiles revealed a close relationship between the expression levels of Hsf genes and various plant tissues and stress treatments throughout fruit ripening. Subcellular localization analysis demonstrated that GFP-AcHsfA2a/AcHsfA7b and AcHsfA2a/AcHsfA7b -GFP were localized in the nucleus, while GFP-AcHsfA2a was also observed in the cytoplasm of Arabidopsis protoplasts. The results of real-time quantitative polymerase chain reaction (RT-qPCR) and dual-luciferase reporter assay revealed that the majority of Hsf genes, especially AcHsfA2a, were expressed under high-temperature conditions. In conclusion, our findings establish a theoretical foundation for analyzing the potential role of Hsfs in high-temperature stress tolerance in kiwifruit. This study also offers valuable information to aid plant breeders in the development of heat-stress-resistant plant materials.

Genome-wide identification of HSF gene family and their expression analysis in vegetative tissue of young seedlings of hemp under different light treatments

Heat shock transcription factors (HSFs), play a crucial role in plant growth, development and defense processes. The functions of some HSFs have been well studied in response some stresses in model plants. At present, the genome of the medicinal plant Cannabis sativa L. has been fully sequenced. Nevertheless, there is little known about the HSF genes family in Cannabis sativa L, as well as a lack of understanding of its evolutionary history. Herein, 18 HSFs were identified in the cannabis genome and phylogenetically classified into three groups based on the structural characteristics and phylogenetic analysis, including classes A (9 genes), classes B (8 genes), and classes C (1 gene). They were distributed over 9 of 10 chromosomes without chromosome 8. Then, the motif composition and evolutionary relationship of CsHSF proteins are discussed in detail, along with gene structures, cis-acting elements in the promoter, and synchronization analysis. Furthermore, our results also revealed that CsHSF transcription levels varied significantly among tissues, suggesting that the functions of CsHSF may be different. Finally, we found that red and blue light treatments had a significant effect on HSF genes expression and cannabinoids accumulation in vegetative organs of hemp young seedlings, implying the expression of HSF genes may regulate the content of cannabinoids under different light conditions. Although cannabinoid biosynthesis and response to light in vegetative organs of hemp young seedlings may not represent the mature stage of hemp, these results provided an essential theoretical basis to elucidate the regulatory mechanism of HSF in cannabinoid biosynthesis in the future.

Exploring the Heat Shock Transcription Factor (HSF) Gene Family in Ginger: A Genome-Wide Investigation on Evolution, Expression Profiling, and Response to Developmental and Abiotic Stresses.

Ginger is a valuable crop known for its nutritional, seasoning, and health benefits. However, abiotic stresses, such as high temperature and drought, can adversely affect its growth and development. Heat shock transcription factors (HSFs) have been recognized as crucial elements for enhancing heat and drought resistance in plants. Nevertheless, no previous study has investigated the HSF gene family in ginger. In this research, a total of 25 ZoHSF members were identified in the ginger genome, which were unevenly distributed across ten chromosomes. The ZoHSF members were divided into three groups (HSFA, HSFB, and HSFC) based on their gene structure, protein motifs, and phylogenetic relationships with Arabidopsis. Interestingly, we found more collinear gene pairs between ZoHSF and HSF genes from monocots, such as rice, wheat, and banana, than dicots like Arabidopsis thaliana. Additionally, we identified 12 ZoHSF genes that likely arose from duplication events. Promoter analysis revealed that the hormone response elements (MEJA-responsiveness and abscisic acid responsiveness) were dominant among the various cis-elements related to the abiotic stress response in ZoHSF promoters. Expression pattern analysis confirmed differential expression of ZoHSF members across different tissues, with most showing responsiveness to heat and drought stress. This study lays the foundation for further investigations into the functional role of ZoHSFs in regulating abiotic stress responses in ginger.

In-silico analysis of heat shock transcription factor (OsHSF) gene family in rice (Oryza sativa L.)

BackgroundOne of the most important cash crops worldwide is rice (Oryza sativa L.). Under varying climatic conditions, however, its yield is negatively affected. In order to create rice varieties that are resilient to abiotic stress, it is essential to explore the factors that control rice growth, development, and are source of resistance. HSFs (heat shock transcription factors) control a variety of plant biological processes and responses to environmental stress. The in-silico analysis offers a platform for thorough genome-wide identification of OsHSF genes in the rice genome.ResultsIn this study, 25 randomly dispersed HSF genes with significant DNA binding domains (DBD) were found in the rice genome. According to a gene structural analysis, all members of the OsHSF family share Gly-66, Phe-67, Lys-69, Trp-75, Glu-76, Phe-77, Ala-78, Phe-82, Ile-93, and Arg-96. Rice HSF family genes are widely distributed in the vegetative organs, first in the roots and then in the leaf and stem; in contrast, in reproductive tissues, the embryo and lemma exhibit the highest levels of gene expression. According to chromosomal localization, tandem duplication and repetition may have aided in the development of novel genes in the rice genome. OsHSFs have a significant role in the regulation of gene expression, regulation in primary metabolism and tolerance to environmental stress, according to gene networking analyses.ConclusionSix genes viz; Os01g39020, Os01g53220, Os03g25080, Os01g54550, Os02g13800 and Os10g28340 were annotated as promising genes. This study provides novel insights for functional studies on the OsHSFs in rice breeding programs. With the ultimate goal of enhancing crops, the data collected in this survey will be valuable for performing genomic research to pinpoint the specific function of the HSF gene during stress responses.

Characterization of the Heat Shock Transcription Factor Family in Medicago sativa L. and Its Potential Roles in Response to Abiotic Stresses.

Heat shock transcription factors (HSFs) are important regulatory factors in plant stress responses to various biotic and abiotic stresses and play important roles in growth and development. The HSF gene family has been systematically identified and analyzed in many plants but it is not in the tetraploid alfalfa genome. We detected 104 HSF genes (MsHSFs) in the tetraploid alfalfa genome ("Xinjiangdaye" reference genome) and classified them into three subgroups: 68 in HSFA, 35 in HSFB and 1 in HSFC subgroups. Basic bioinformatics analysis, including genome location, protein sequence length, protein molecular weight and conserved motif identification, was conducted. Gene expression analysis revealed tissue-specific expression for 13 MsHSFs and tissue-wide expression for 28 MsHSFs. Based on transcriptomic data analysis, 21, 11 and 27 MsHSFs responded to drought stress, cold stress and salt stress, respectively, with seven responding to all three. According to RT-PCR, MsHSF27/33 expression gradually increased with cold, salt and drought stress condition duration; MsHSF6 expression increased over time under salt and drought stress conditions but decreased under cold stress. Our results provide key information for further functional analysis of MsHSFs and for genetic improvement of stress resistance in alfalfa.

Alternative splicing of TaHSFA6e modulates heat shock protein-mediated translational regulation in response to heat stress in wheat.

Heat stress greatly threatens crop production. Plants have evolved multiple adaptive mechanisms, including alternative splicing, that allow them to withstand this stress. However, how alternative splicing contributes to heat stress responses in wheat (Triticum aestivum) is unclear. We reveal that the heat shock transcription factor gene TaHSFA6e is alternatively spliced in response to heat stress. TaHSFA6e generates two major functional transcripts: TaHSFA6e-II and TaHSFA6e-III. TaHSFA6e-III enhances the transcriptional activity of three downstream heat shock protein 70 (TaHSP70) genes to a greater extent than does TaHSFA6e-II. Further investigation reveals that the enhanced transcriptional activity of TaHSFA6e-III is due to a 14-amino acid peptide at its C-terminus, which arises from alternative splicing and is predicted to form an amphipathic helix. Results show that knockout of TaHSFA6e or TaHSP70s increases heat sensitivity in wheat. Moreover, TaHSP70s are localized in stress granule following exposure to heat stress and are involved in regulating stress granule disassembly and translation re-initiation upon stress relief. Polysome profiling analysis confirms that the translational efficiency of stress granule stored mRNAs is lower at the recovery stage in Tahsp70s mutants than in the wild types. Our finding provides insight into the molecular mechanisms by which alternative splicing improves the thermotolerance in wheat.

Characterization, Evolutionary Analysis, and Expression Pattern Analysis of the Heat Shock Transcription Factors and Drought Stress Response in Heimia myrtifolia

Heat shock transcription factors (HSFs) are among the most important regulators of plant responses to abiotic stimuli. They play a key role in numerous transcriptional regulatory processes. However, the specific characteristics of HSF gene family members and their expression patterns in different tissues and under drought stress have not been precisely investigated in Heimia myrtifolia. This study analyzed transcriptome data from H. myrtifolia and identified 15 members of the HSF family. Using a phylogenetic tree, these members were classified into three major classes and fifteen groups. The amino acid physicochemical properties of these members were also investigated. The results showed that all HmHSF genes are located in the nucleus, and multiple sequence alignment analysis revealed that all HmHSF proteins have the most conserved DBD structural domains. Interestingly, a special HmHSF15 protein was found in the three-dimensional structure of the protein, which has a conserved structural domain that performs a function in addition to the unique structural domain of HSF proteins, resulting in a three-dimensional structure for HmHSF15 that is different from other HmHSF proteins. GO enrichment analysis shows that most HmHSFA-like genes are part of various biological processes associated with abiotic stresses. Finally, this study analyzed the tissue specificity of HmHSF genes in different parts of H. myrtifolia by qRT-PCR and found that HmHSF genes were more abundantly expressed in roots than in other tissues, and HmHSF05, HmHSF12, and HmHSF14 genes were different from other HSF genes, which could be further analyzed to verify their functionality. The results provide a basis for analyzing the functions of HmHSF genes in H. myrtifolia and help to explore the molecular regulatory mechanism of HmHSF in response to drought stress.

QTL Mapping for Seed Tocopherol Content in Soybean

Tocopherol plays an important role as a powerful antioxidant in human beings and in plants. This study investigated the genetic basis of tocopherol content in soybean. A RIL population of 192 lines derived from 2 cultivars, ZH13 and ZH35, was evaluated for tocopherol content across 3 environments. QTL mapping identified 38 QTL for tocopherol, with stable QTL identified on Chromosomes 5 and 12. Ninety polymorphic genes were identified from these regions. Further SNP variation of a natural population identified 47 SNPs, with missense variants in 19 genes, including the heat shock transcription factor gene (GmHSFA8) and gamma-tocopherol methyltransferase (GmVTE4), potentially related to tocopherol accumulation in soybean. Haplotype analysis revealed significant variations in these missense variants in the natural population. This study provides insights into the genetic mechanisms underlying tocopherol content in soybean, which is important for breeding high tocopherol soybean cultivars.

Insights into genomic variations in rice Hsp100 genes across diverse rice accessions

The Hsp101 gene is present across all sequenced rice genomes. However, as against Japonica rice, Hsp101 protein of most indica and aus rice contain insertion of glutamic acid at 907th position. The understanding of the heat stress response of rice plants is important for worldwide food security. We examined the presence/absence variations (PAVs) of heat shock proteins (Hsps)/heat shock transcription factor (Hsf) genes in cultivated rice accessions. While 53 Hsps/Hsfs genes showed variable extent of PAVs, 194 genes were the core genes present in all the rice accessions. ClpB1/Hsp101 gene, which is critically important for thermotolerance in plants, showed 100% distribution across the rice types. Within the ClpB1 gene sequence, 40 variation sites consisting of nucleotide polymorphisms (SNPs) and short insertion/deletions (InDels) were discerned. An InDel in ClpB1 leading to an in-frame insertion of 3 nucleotides (TCC) thereby an additional amino acid (glutamic acid) at 907th amino acid position was noted in most of the indica and aus as against japonica rice types. Three rice types namely Moroberekan (japonica), IR64 (indica) and N22 (aus) were further analyzed to address the question of ClpB1 genomic variations and its protein levels with the heat tolerance phenotype. The growth profiling analysis in the post heat stress (HS) period showed that N22 seedlings were most tolerant, IR64 moderately tolerant and Moroberekan highly sensitive. Importantly, the ClpB1 protein sequences of these three rice types showed distinct differences in terms of SNPs. As the ClpB1 protein levels accumulated post HS were generally higher in Moroberekan than N22 seedlings in our study, it is proposed that some additional gene loci in conjunction with ClpB1 regulate the overall rice heat stress response.