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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.

Plant heat shock transcription factors (Hsfs) are important regulators of heat shock signal transduction pathway. There are 30 members of the Hsf family in maize, only two of which, ZmHsf06 and ZmHsf12, belong to subclass A1. Our previous work demonstrated that ZmHsf06-overexpressing Arabidopsis lines showed improved tolerance to heat and drought stresses. In this study, we isolated ZmHsf12 from young leaves of maize (Zea mays L.) using homologous cloning methods. The CDS (coding sequence) of ZmHsf12 is 1,494 bp and encodes a putative protein consisting of 497 amino acids which possesses domains such as DBD (DNA-binding domain), OD (oligomerization domain), NLS (nuclear localization signal), NES (nuclear export signal), and an AHA (activator) motif. The ZmHsf12-GFP fusion protein is localized to the cell nucleus. ZmHsf12 was expressed in many maize organs, and its expression was up-regulated by heat shock. Furthermore, we characterized the function of ZmHsf12 in yeast and Arabidopsis. Yeast cells overexpressing ZmHsf12 showed enhanced heat tolerance. ZmHsf12-overexpressing Arabidopsis seedlings displayed significant increases in both basal and acquired thermotolerance. Compared to WT seedlings, the ZmHsf12-overexpressing lines displayed both increased chlorophyll contents and higher survival rates. Also, the expression of AtHsps was increased higher in the ZmHsf12-overexpressing Arabidopsis lines after heat stress. The results of our study strongly suggested that ZmHsf12 may take part in plant response to heat stress.

Heat shock transcription factor (Hsf) plays a transcriptional regulatory role in plants during heat stress and other abiotic stresses. 31 non-redundant ZmHsf genes from maize were identified and clustered in the reference genome sequenced by Single Molecule Real Time (SMRT). The amino acid length, chromosome location, and presence of functional domains and motifs of all ZmHsfs sequences were analyzed and determined. Phylogenetics and collinearity analyses reveal gene duplication events in Hsf family and collinearity blocks shared by maize, rice and sorghum. The results of RNA-Seq analysis of anthesis and post-anthesis periods in maize show different expression patterns of ZmHsf family members. Specially, ZmHsf26 of A2 subclass and ZmHsf23 of A6 subclass were distinctly up-regulated after heat shock (HS) at post-anthesis stage. Nanopore transcriptome sequencing of maize seedlings showed that alternative splicing (AS) events occur in ZmHsf04 and ZmHsf17 which belong to subclass A2 after heat shock. Through sequence alignment, semi-quantitative and quantitative RT-PCR, we found that intron retention events occur in response to heat shock, and newly splice isoforms, ZmHsf04-II and ZmHsf17-II, were transcribed. Both new isoforms contain several premature termination codons in their introns which may lead to early termination of translation. The ZmHsf04 expression was highly increased than that of ZmHsf17, and the up-regulation of ZmHsf04-I transcription level were significantly higher than that of ZmHsf04-II after HS.

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. Electronic supplementary material The online version of this article (10.1186/s12864-019-5617-1) contains supplementary material, which is available to authorized users.

High temperature directly affects the yield and quality of crops. Plant Hsfs play vital roles in plant response to heat shock. In the present study, ZmHsf05 was isolated from maize (Zea mays L.) using homologous cloning methods. The sequencing analysis demonstrated that CDS of ZmHsf05 was 1080 bp length and encoded a protein containing 359 amino acids. The putative amino acid sequence of ZmHsf05 contained typical Hsf domains, such as DBD, OD, NLS and AHA motif. Subcellular localization assays displayed that the ZmHsf05 is localized to the nucleus. ZmHsf05 was expressed in many maize tissues and its expression level was increased by heat stress treatment. ZmHsf05 rescued the reduced thermotolerance of the athsfa2 mutant in Arabidopsis seedlings. Arabidopsis seedlings of ZmHsf05-overexpressing increased both the basal and acquired thermotolerances. After heat stress, the ZmHsf05-overexpressing lines showed enhanced survival rate and chlorophyll content compared with WT seedlings. The expression of Hsps was up-regulated in the ZmHsf05-overexpressing Arabidopsis lines after heat stress treatment. These results suggested that ZmHsf05 plays an important role in both basal and acquired thermotolerance in plants.

Background Heat waves can critically influence maize crop yields. Plant heat shock transcription factors (HSFs) play a key regulating role in the heat shock (HS) signal transduction pathway. Method In this study, a homologous cloning method was used to clone HSF gene ZmHsf01 (accession number: MK888854) from young maize leaves. The transcript levels of ZmHsf01 were detected using qRT-PCR in different tissues and treated by HS, abscisic acid (ABA), hydrogen peroxide (H2O2), respectively, and the functions of gene ZmHsf01 were studied in transgenic yeast and Arabidopsis. Result ZmHsf01 had a coding sequence (CDS) of 1176 bp and encoded a protein consisting of 391 amino acids. The homologous analysis results showed that ZmHsf01 and SbHsfA2d had the highest protein sequence identities. Subcellular localization experiments confirmed that ZmHsf01 was localized in the nucleus. ZmHsf01 was expressed in many maize tissues. It was up-regulated by HS, and up-regulated in roots and down-regulated in leaves under ABA and H2O2treatments. ZmHsf01-overexpressing yeast cells showed increased thermotolerance. In Arabidopsis seedlings, ZmHsf01 compensated for the thermotolerance defects of mutant athsfa2, and ZmHsf01-overexpressing lines showed enhanced basal and acquired thermotolerance. When compared to wild type (WT) seedlings, ZmHsf01-overexpressing lines showed higher chlorophyll content and survival rates after HS. Heat shock protein (HSP) gene expression levels were more up-regulated in ZmHsf01-overexpressing Arabidopsis seedlings than WT seedlings. These results suggest that ZmHsf01 plays a vital role in response to HS in plant.

Heat shock transcription factors (Hsfs) play an important role in regulating heat stress response in plants. Our previous study found that there were 82 non-redundant Hsfs in wheat, 18 of which belonged to subclass A2. In this study, we cloned an A2 member, TaHsfA2-1, which encoded a protein of 346 amino acid residues in wheat. The fusion protein TaHsfA2-1-GFP was localized in the nucleus under normal growth conditions. TaHsfA2-1 was expressed in nearly all the measured tissues, most highly in mature leaves. The expression level of TaHsfA2-1 can be enhanced by heat stress, PEG stress, and signal molecules such as H2O2 and SA. Yeast cells transformed with TaHsfA2-1 improved thermotolerance compared to those with the empty vector. TaHsfA2-1-overexpressing Arabidopsis displayed a better growth state with more green leaves than wild-type seedlings after heat stress. Accordingly, the chlorophyll content and survival rate in the transgenic lines were higher than in the wild type, and relative conductivity in the transgenic lines was lower than in the wild type. Further research found that TaHsfA2-1-overexpressing Arabidopsis up-regulated the expression of some heat shock protein genes (Hsps) compared to wild type after heat stress. These results suggested that TaHsfA2-1 is a new gene that improves thermotolerance in plants by mediating the expression of Hsps. A functional gene was provided for molecular breeding in the subsequent research.