Transcriptome-wide identification of the Hsp70 gene family in Pugionium cornutum and functional analysis of PcHsp70-5 under drought stress.

MAIN CONCLUSION: The PcHsp70-5 enhances drought stress tolerance in transgenic Arabidopsis thaliana by upregulating stress tolerance genes and antioxidant enzyme activities. Heat shock proteins (HSPs) constitute a class of evolutionarily conserved proteins synthesized by organisms in response to various adverse environmental stimuli such as elevated temperatures, drought, hormonal fluctuations, high salt concentrations, and mechanical stress. However, research on HSPs has predominantly focused on model plants and crops, whereas their functions in desert plants have not been well investigated. This study analyzed the transcriptome of Pugionium cornutum and identified the complete ORFs of 25 genes of the PcHsp70 family genes. Their expression levels under drought stress were investigated using existing RNA-seq data. PcHsp70-5 genes exhibited high expression levels in both roots and leaves under drought stress. Consequently, the PcHsp70-5 genes were cloned and transformed into Arabidopsis thaliana for further analysis of their roles in drought stress response. Real-time fluorescence quantitative PCR (qRT-PCR) analysis demonstrated that both, drought stress and ABA, induced PcHsp70-5 expression. Under drought conditions, transgenic Arabidopsis plants exhibited markedly enhanced growth compared to wild-type plants, as evidenced by improved survival rates, root length, fresh weight, chlorophyll content, and reduced levels of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in leaves, indicating that PcHsp70-5 overexpression mitigated growth inhibition and oxidative damage induced by drought stress. Subsequent research revealed that PcHsp70-5 overexpression significantly augmented the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and increased the proline content in transgenic Arabidopsis under drought conditions, alongside a significant increase in the expression levels of genes related to stress tolerance. This suggests that PcHsp70-5 enhances drought stress tolerance in transgenic Arabidopsis by upregulating stress tolerance genes and antioxidant enzyme activities.

Genome-wide analysis of HSP70 gene superfamily in Pyropia yezoensis (Bangiales, Rhodophyta): identification, characterization and expression profiles in response to dehydration stress.

BACKGROUND: Heat shock proteins (HSPs) perform a fundamental role in protecting plants against abiotic stresses. Individual family members have been analyzed in previous studies, but there has not yet been a comprehensive analysis of the HSP70 gene family in Pyropia yezoensis. RESULTS: We investigated 15 putative HSP70 genes in Py. yezoensis. These genes were classified into two sub-families, denoted as DnaK and Hsp110. In each sub-family, there was relative conservation of the gene structure and motif. Synteny-based analysis indicated that seven and three PyyHSP70 genes were orthologous to HSP70 genes in Pyropia haitanensis and Porphyra umbilicalis, respectively. Most PyyHSP70s showed up-regulated expression under different degrees of dehydration stress. PyyHSP70-1 and PyyHSP70-3 were expressed in higher degrees compared with other PyyHSP70s in dehydration treatments, and then expression degrees somewhat decreased in rehydration treatment. Subcellular localization showed PyyHSP70-1-GFP and PyyHSP70-3-GFP were in the cytoplasm and nucleus/cytoplasm, respectively. Similar expression patterns of paired orthologs in Py. yezoensis and Py. haitanensis suggest important roles for HSP70s in intertidal environmental adaptation during evolution. CONCLUSIONS: These findings provide insight into the evolution and modification of the PyyHSP70 gene family and will help to determine the functions of the HSP70 genes in Py. yezoensis growth and development.

In Silico Analysis of HSP70 Gene Family in Bovine Genome.

Heat shock proteins (HSPs), members of molecular chaperones families fulfill essential roles under normal conditions and provide protection and adaptation during and after stress. Among different HSPs, HSP70 kDa family of proteins is most abundant and well-studied in human and mouse but has not yet been characterized in bovines. In silico analysis was performed to characterize members of HSP70 gene family in bovine genome and a total of 17 genes of bovine HSP70 gene family were identified. The members of HSP70 family were distributed over 12 chromosomes with gene size ranging from 1911 (HSPA2) to 54,017 bp (HSPA4). Five genes were intronless, while rest of 12 genes were multiexonic. Phylogenetic analysis of HSP70 gene family distinguished them into eight major evolutionary groups wherein members of group 1 were most divergent and quite dissimilar than from rest of the HSP70 sequences. Domain structure of all bovine HSP70 genes was conserved and three signature patterns HSP70_1, HSP70_2, and HSP70_3 were identified. HSPA8, HSP9, and HSPA1A showed comparatively higher expression in majority of tissues. Like humans, bovine HSP70 family was characterized by remarkable evolutionary diversity. The analysis also suggested resemblance of bovine HSP70 family to that of human compared to mouse. Overall, the study indicates the presence of diversity for structure, function, localization, and expression in the bovine HSP70 family chaperons which could form the basis to understand thermotolerance/adaptive changes in the bovines.

[Identification and expression analysis of the HSP70 gene family under abiotic stresses in Litchi chinensis].

HSP70 protein, as an important member of the heat shock protein (HSP) family, plays an important role in plant growth, development, and response to biotic and abiotic stresses. In order to explore the role of HSP70 gene family members in Litchi chinensis under low temperature, high temperature, drought, and salt stress, bioinformatics methods were used to identify the HSP70 gene family members within the entire L. chinensis genome. The expression of these genes under various abiotic stresses was then detected using quantitative real-time PCR (qRT-PCR). The results showed that the LcHSP70 gene family consisted of 18 members, which were unevenly distributed across ten L. chinensis chromosomes. The LcHSP70 protein contained 479-851 amino acids, with isoelectric points ranging from 5.07 to 6.95, and molecular weights from 52.44 kDa to 94.07 kDa. The predicted subcellular localization showed that LcHSP70 protein was present in the nucleus, cytoplasm, endoplasmic reticulum, mitochondria, and chloroplast. Phylogenetic analysis divided the LcHSP70 proteins into five subgroups, namely Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅵ. The promoter regions of the LcHSP70 genes contained various cis-acting elements related to plant growth, development, hormone response, and stress response. Moreover, the expression of LcHSP70 genes displayed distint tissue-specific expression level, categorized into universal expression and specific expression. From the selected 6 LcHSP70 genes (i.e., LcHSP70-1, LcHSP70-5, LcHSP70-10, LcHSP70-14, LcHSP70-16, and LcHSP70-18), their relative expression levels were assessed under different abiotic stresses using qRT-PCR. The results indicated that the gene family members exhibited diverse responses to low temperature, high temperature, drought, and salt stress, with significant variations in their expression levels across different time periods. These results provide a foundation for further exploration of the function of the LcHSP70 gene family.

Genome-wide analysis of Hsp40 and Hsp70 gene family in four cotton species provides insights into their involvement in response to Verticillium dahliae and abiotic stress.

Introduction: Cotton is an important economic crop to provide natural fibers as raw materials to textile industry, and is significantly affected by biotic and abiotic stress during the whole growth stage, in which Verticillium wilt (VW) caused by Verticillium dahliae is one of the most destructive disease to lead to a significant yield reduction. Heat shock proteins (Hsps) are important molecular chaperones, and play crucial roles in plant growth, development, resistance to biotic and abiotic stress. Hsp40 and Hsp70 are two key Hsps in cell chaperone network, however, the function and regulatory mechanism of Hsp40 and Hsp70 members in VW resistance and abiotic stress in cotton are largely unknown. Methods and Results: Herein, a systematic and comprehensive analysis of Hsp40s and Hsp70s in four cotton species of Gossypium arboretum, G. raimondii, G. hirsutum, and G. barbadense were performed. A total of 291 Hsp40s and 171 Hsp70s identified in four Gossypium species. Sequence analysis revealed that all Hsp40 proteins contained J domain that provides the binding sites to Hsp70. Protein-protein interaction prediction analysis displayed that GhHsp40-55 might interact with GhHsp70-2 and GhHsp70-13, suggesting their potential function as protein complex. Promoter cis-acting element analysis demonstrated that multiple cis-elements related to disease and stress response consists in GhHsp40 and GhHsp70 promoters. Further expression analysis showed that eight GhHsp40s (Hsp40-2,4,8,11,20,23,53,55) and seven GhHsp70s (Hsp70-2,3,6,8,13,19,22) were up-regulated after V. dahliae infection. In addition, five GhHsp40s (Hsp40-2,8,11,53,55) and four GhHsp70s (Hsp70-3,6,8,13) were up-regulated after salt treatment, six GhHsp40s (Hsp40-4,11,20,23) and three GhHsp70s (Hsp70-2,8,19) were up-regulated after drought treatment, four GhHsp40s (Hsp40-2,11,20,23) and four GhHsp70s (Hsp70-3,6,19,22) were up-regulated after temperature treatment, suggesting these Hsps have possible important function in the process of abiotic stress response. Discussion: Our results lay a foundation for understanding the function of Hsp40 and Hsp70 in the resistance against V. dahliae and abiotic stress, and elucidating the regulatory mechanism of the protein complex, evolution and molecular mechanism under stress.

Transcriptome profiling reveals the strategy of thermal tolerance enhancement caused by heat-hardening in Mytilus coruscus.

The thick-shell mussel Mytilus coruscus serves as a common sessile intertidal species and holds economic significance as an aquatic organism. M. coruscus often endure higher temperatures than their ideal range during consecutive low tides in the spring. This exposure to elevated temperatures provides them with a thermal tolerance boost, enabling them to adapt to high-temperature events caused by extreme low tides and adverse weather conditions. This phenomenon is referred to as heat-hardening. Some related studies showed the phenomenon of heat-hardening in sessile intertidal species but not reported at the mechanism level based on transcriptome so far. In this study, physiological experiments, gene family identification and transcriptome sequencing were performed to confirm the thermotolerance enhancement based on heat-hardening and explore the mechanism in M. coruscus. A total of 2935 DEGs were identified and the results of the KEGG enrichment showed that seven heat-hardening relative pathways were enriched, including Toll-like receptor signal pathway, Arachidonic acid metabolism, and others. Then, 24 HSP70 members and 36 CYP2 members, were identified, and the up-regulated members are correlated with increasing thermotolerance. Finally, we concluded that the heat-hardening M. coruscus have a better thermotolerance because of the capability of maintaining the integrity and the phenomenon of vasodilation of the gill under thermal stress. Further, the physiological experiments yielded the same conclusions. Overall, this study confirms the thermotolerance enhancement caused by heat-hardening and reveals the survival strategy in M. coruscus. In addition, the conclusion provides a new reference for studying the intertidal species' heat resistance mechanisms to combat extreme heat events and the strategies for dealing with extreme weather in aquaculture under the global warming trend.

Genome-wide identification and phylogenetic relationships of the Hsp70 gene family of Aegilops tauschii, wild emmer wheat (Triticum dicoccoides) and bread wheat (Triticum aestivum).

Heat shock protein 70 (Hsp70) plays an important role in plant development. It is closely related to the physiological process of cell development and the response to abiotic and biological stress. However, the classification and evolution of Hsp70 genes in bread wheat, wild emmer wheat and Aegilops tauschii are still unclear. Therefore, this study conducted a comprehensive bioinformatics analysis of Hsp70 gene in three species. Among these three species, 113, 79 and 36 Hsp70 genes were identified. They are divided into six subfamilies. Group vi-1 is different from Arabidopsis thaliana. It may be the result of early evolutionary segregation. The number of exons in different subfamilies (from 1 to 13) was different, but the distribution patterns of exons / introns in the same subfamily were similar. The results of Hsp70 promoter region analysis showed that the cis-regulatory elements of A. tauschii and wild emmer wheat were different from those of wheat. In addition, CpG island proportion of wild emmer Hsp70 was higher than that of wheat, which may be the molecular basis of heat resistance of wild wheat relative to cultivated wheat. Further comprehensive analysis of chromosome location and repeat events of Hsp70 gene showed that whole-genome duplication and tandem duplication events contributed to the evolution and expansion of Hsp70 gene in wheat. The results of non-synonymous substitution and synonymous substitution analysis showed that Hsp70 genes of three species had undergone purification selection. The expression profile analysis showed that Hsp70 gene was highly expressed in the roots during the vegetative growth period. In addition, TaHsp70 gene was highly expressed under various stress. The identification, classification and evolution of Hsp70 in wheat and its relatives provided a basis for further research on its evolution and its molecular mechanism in response to stress. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02639-5.

Genome-wide identification and characterization of the Hsp70 gene family in allopolyploid rapeseed (Brassica napus L.) compared with its diploid progenitors.

Heat shock protein 70 (Hsp70) plays an essential role in plant growth and development, as well as stress response. Rapeseed (Brassica napus L.) originated from recently interspecific hybridization between Brassica rapa and Brassica oleracea. In this study, a total of 47 Hsp70 genes were identified in B. napus (AnAnCnCn genome), including 22 genes from An subgenome and 25 genes from Cn subgenome. Meanwhile, 29 and 20 Hsp70 genes were explored in B. rapa (ArAr genome) and B. oleracea (CoCo genome), respectively. Based on phylogenetic analysis, 114 Hsp70 proteins derived from B. napus, B. rapa, B. oleracea and Arabidopsis thaliana, were divided into 6 subfamilies containing 16 Ar-An and 11 Co-Cn reliable orthologous pairs. The homology and synteny analysis indicated whole genome triplication and segmental duplication may be the major contributor for the expansion of Hsp70 gene family. Intron gain of BnHsp70 genes and domain loss of BnHsp70 proteins also were found in B. napus, associating with intron evolution and module evolution of proteins after allopolyploidization. In addition, transcriptional profiles analyses indicated that expression patterns of most BnHsp70 genes were tissue-specific. Moreover, Hsp70 orthologs exhibited different expression patterns in the same tissue and Cn subgenome biased expression was observed in leaf. These findings contribute to exploration of the evolutionary adaptation of polyploidy and will facilitate further application of BnHsp70 gene functions.

Genome-wide analysis and expression profiling under heat and drought treatments of HSP70 gene family in soybean (Glycine max L.).

Heat shock proteins (HSPs) perform a fundamental role in protecting plants against abiotic stresses. Previous studies have made great efforts in the functional analysis of individual family members, but there has not yet been an overall analysis or expression profiling of the HSP70 gene family in soybeans (Glycine max L.). In this study, an investigation of the soybean genome revealed 61 putative HSP70 genes, which were evaluated. These genes were classified into eight sub-families, denoted I-VIII, based on a phylogenetic analysis. In each sub-family, the constituent parts of the gene structure and motif were relatively conserved. These GmHSP70 genes were distributed unequally on 17 of the 20 chromosomes. The analysis of the expression profiles showed that 53 of the 61 GmHSP70 genes were differentially expressed across the 14 tissues. However, most of the GmHSP70s were differentially expressed in a tissue-specific expression pattern. Furthermore, the expression of some of the duplicate genes was partially redundant, while others showed functional diversity. The quantitative real-time PCR (qRT-PCR) analysis of the 61 soybean HSP70 genes confirmed their stress-inducible expression patterns under both drought and heat stress. These findings provide a thorough overview of the evolution and modification of the GmHSP70 gene family, which will help to determine the functional characteristics of the HSP70 genes in soybean growth and development.