Genome-Wide Identification, Classification and Expression Analysis of the HSP Gene Superfamily in Tea Plant (Camellia sinensis)

Investigation of heat stress responses and adaptation mechanisms by integrative metabolome and transcriptome analysis in tea plants (Camellia sinensis)

Extreme high temperature has deleterious impact on the yield and quality of tea production, which has aroused the attention of growers and breeders. However, the mechanisms by which tea plant varieties respond to extreme environmental heat is not clear. In this study, we analyzed physiological indices, metabolites and transcriptome differences in three different heat-tolerant tea plant F1 hybrid progenies. Results showed that the antioxidant enzyme activity, proline, and malondialdehyde were significantly decreased in heat-sensitive 'FWS' variety, and the accumulation of reactive oxygen molecules such as H2O2 and O2- was remarkably increased during heat stress. Metabolomic analysis was used to investigate the metabolite accumulation pattern of different varieties in response to heat stress. The result showed that a total of 810 metabolites were identified and more than 300 metabolites were differentially accumulated. Transcriptional profiling of three tea varieties found that such genes encoding proteins with chaperon domains were preferentially expressed in heat-tolerant varieties under heat stress, including universal stress protein (USP32, USP-like), chaperonin-like protein 2 (CLP2), small heat shock protein (HSP18.1), and late embryogenesis abundant protein (LEA5). Combining metabolomic with transcriptomic analyses discovered that the flavonoids biosynthesis pathway was affected by heat stress and most flavonols were up-regulated in heat-tolerant varieties, which owe to the preferential expression of key FLS genes controlling flavonol biosynthesis. Take together, molecular chaperons, or chaperon-like proteins, flavonols accumulation collaboratively contributed to the heat stress adaptation in tea plant. The present study elucidated the differences in metabolite accumulation and gene expression patterns among three different heat-tolerant tea varieties under extreme ambient high temperatures, which helps to reveal the regulatory mechanisms of tea plant adaptation to heat stress, and provides a reference for the breeding of heat-tolerant tea plant varieties.

Upregulation of TaHSP90A transcripts enhances heat tolerance and increases grain yield in wheat under changing climate conditions

Plants have certain adaptation mechanisms to combat temperature extremes and fluctuations. The heat shock protein (HSP90A) plays a crucial role in plant defence mechanisms under heat stress. In silico analysis of the eight TaHSP90A transcripts showed diverse structural patterns in terms of intron/exons, domains, motifs and cis elements in the promoter region in wheat. These regions contained cis elements related to hormones, biotic and abiotic stress and development. To validate these findings, two contrasting wheat genotypes E-01 (thermo-tolerant) and SHP-52 (thermo-sensitive) were used to evaluate the expression pattern of three transcripts TraesCS2A02G033700.1, TraesCS5B02G258900.3 and TraesCS5D02G268000.2 in five different tissues at five different temperature regimes. Expression of TraesCS2A02G033700.1 was upregulated (2-fold) in flag leaf tissue after 1 and 4h of heat treatment in E-01. In contrast, SHP-52 showed downregulated expression after 1h of heat treatment. Additionally, it was shown that under heat stress, the increased expression of TaHSP90A led to an increase in grain production. As the molecular mechanism of genes involved in heat tolerance at the reproductive stage is mostly unknown, these results provide new insights into the role of TaHSP90A transcripts in developing phenotypic plasticity in wheat to develop heat-tolerant cultivars under the current changing climate scenario.

Genome-wide identification, evolution, and role of SPL gene family in beet (Beta vulgaris L.) under cold stress

BACKGROUND

SPL transcription factors play vital roles in regulating plant growth, development, and abiotic stress responses. Sugar beet (Beta vulgaris L.), one of the world's main sugar-producing crops, is a major source of edible and industrial sugars for humans. Although the SPL gene family has been extensively identified in other species, no reports on the SPL gene family in sugar beet are available.

RESULTS

Eight BvSPL genes were identified at the whole-genome level and were renamed based on their positions on the chromosome. The gene structure, SBP domain sequences, and phylogenetic relationship with Arabidopsis were analyzed for the sugar beet SPL gene family. The eight BvSPL genes were divided into six groups (II, IV, V, VI, VII, and VIII). Of the BvSPL genes, no tandem duplication events were found, but one pair of segmental duplications was present. Multiple cis-regulatory elements related to growth and development were identified in the 2000-bp region upstream of the BvSPL gene start codon (ATG). Using quantitative real-time polymerase chain reaction (qRT-PCR), the expression profiles of the eight BvSPL genes were examined under eight types of abiotic stress and during the maturation stage. BvSPL transcription factors played a vital role in abiotic stress, with BvSPL3 and BvSPL6 being particularly noteworthy.

CONCLUSION

Eight sugar beet SPL genes were identified at the whole-genome level. Phylogenetic trees, gene structures, gene duplication events, and expression profiles were investigated. The qRT-PCR analysis indicated that BvSPLs play a substantial role in the growth and development of sugar beet, potentially participating in the regulation of root expansion and sugar accumulation.

Spatiotemporal expression patterns of cytosolic AtHSP90-2 in Arabidopsis seedlings

Heat shock protein AtHSP90-2 is one of the three constitutive cytosolic HSP90s of Arabidopsis thaliana, which are highly homologous and show mild expression activation in response to stressful impacts. To characterize the functioning of AtHSP90-2, we have analyzed tissue-specificity of its expression during seedling development using a DsG transgenic line carrying a loss-of-function mutation of AtHSP90-2 via translational fusions with the β-glucuronidase reporter gene (GUS). Histochemical analysis during the first two weeks of seedling growth revealed AtHSP90-2 expression in all organs, as well as differences in its intensity between tissues and showed its dynamics. The tissue-specific AtHSP90-2-GUS expression pattern was shown to be maintained under heat shock and water deficit. The most prominent GUS staining was detected in the vascular system and hydathodes of cotyledons, and stipules. The basipetal gradient of AtHSP90-2 expression during leaf formation, its dynamics in developing stipules, and the high level of its expression in cells with active transport function suggest a special role for the gene in certain cellular processes.

HSF and Hsp Gene Families in sunflower: a comprehensive genome-wide determination survey and expression patterns under abiotic stress conditions

Sunflowers belong to the Asteraceae family, which comprises nutrimental and economic oilseed plants. Heat shock proteins (Hsps) are protein families vital for all organisms' growth and survival. Besides the ordinary conditions, the expression of these proteins ascends during abiotic stress factors such as high temperature, salinity, and drought. Using bioinformatics approaches, the current study identified and analyzed HSF and Hsp gene family members in the sunflower (Helianthus annuus L.) plant. HSF, sHsp, Hsp40, Hsp60, Hsp70, Hsp90, and Hsp100 domains were analyzed in the sunflower genome, and 88, 72, 192, 52, 85, 49, and 148 genes were identified, respectively. The motif structures of the proteins in the same phylogenetic tree were similar, and the α-helical form was dominant in all the protein families except for sHsp. The estimated three-dimensional structure of 28 sHsp proteins was determined as β-sheets. Considering protein-protein interactions, the Hsp60-09 protein (38 interactions) was found to be the most interacting protein. The most orthologous gene pairs (58 genes) were identified between Hsp70 genes and Arabidopsis genes. The expression analysis of selected genes was performed under high temperature, drought, and high temperature-drought combined stress conditions in two sunflower cultivars. In stress conditions, gene expressions were upregulated for almost all genes in the first half and first hours at large. The expressions of HanHSF-45 and HanHsp70-29 genes were raised in two cultivars under high temperature and high temperature-drought combined stress conditions. This study presents a blueprint for subsequent research and delivers comprehensive knowledge of this vital protein domain.

Genome-wide identification and expression analysis of Hsp70 family genes in Cassava (Manihot esculenta Crantz)

Hsp70 proteins function as molecular chaperones, regulating various cellular processes in plants. In this study, a genome-wide analysis led to the identification of 22 Hsp70 (MeHsp70) genes in cassava. Phylogenetic relationship studies with other Malpighiales genomes (Populus trichocarpa, Ricinus communis and Salix purpurea) classified MeHsp70 proteins into eight groups (Ia, Ib, Ic, Id, Ie, If, IIa and IIb). Promoter analysis of MeHsp70 genes revealed the presence of tissue-specific, light, biotic and abiotic stress-responsive cis-regulatory elements showing their functional importance in cassava. Meta-analysis of publically available RNA-seq transcriptome datasets showed constitutive, tissue-specific, biotic and abiotic stress-specific expression patterns among MeHsp70s in cassava. Among 22 Hsp70, six MeHsp70s viz., MecHsp70-3, MecHsp70-6, MeBiP-1, MeBiP-2, MeBiP-3 and MecpHsp70-2 displayed constitutive expression, while three MecHsp70s were induced under both drought and cold stress conditions. Five MeHsp70s, MecHsp70-7, MecHsp70-11, MecHsp70-12, MecHsp70-13, and MecHsp70-14 were induced under drought stress conditions. We predicted that 19 MeHsp70 genes are under the regulation of 24 miRNAs. This comprehensive genome-wide analysis of the Hsp70 gene family in cassava provided valuable insights into their functional roles and identified various potential Hsp70 genes associated with stress tolerance and adaptation to environmental stimuli.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03760-3.

Characterization of HSP70 family in watermelon (Citrullus lanatus): identification, structure, evolution, and potential function in response to ABA, cold and drought stress

Watermelon (Citrullus lanatus) as a crop with important economic value, is widely cultivated around the world. The heat shock protein 70 (HSP70) family in plant is indispensable under stress conditions. However, no comprehensive analysis of watermelon HSP70 family is reported to date. In this study, 12 ClHSP70 genes were identified from watermelon, which were unevenly located in 7 out of 11 chromosomes and divided into three subfamilies. ClHSP70 proteins were predicted to be localized primarily in cytoplasm, chloroplast, and endoplasmic reticulum. Two pairs of segmental repeats and 1 pair of tandem repeats existed in ClHSP70 genes, and ClHSP70s underwent strong purification selection. There were many abscisic acid (ABA) and abiotic stress response elements in ClHSP70 promoters. Additionally, the transcriptional levels of ClHSP70s in roots, stems, true leaves, and cotyledons were also analyzed. Some of ClHSP70 genes were also strongly induced by ABA. Furthermore, ClHSP70s also had different degrees of response to drought and cold stress. The above data indicate that ClHSP70s may be participated in growth and development, signal transduction and abiotic stress response, laying a foundation for further analysis of the function of ClHSP70s in biological processes.

Genome-Wide Identification and Expression Profiling of Pathogenesis-Related Protein 1 (PR-1) Genes in Durum Wheat (Triticum durum Desf.)

Pathogen-related proteins (PRs) are diversified proteins with a low molecular weight implicated in plant response to biotic and abiotic stress as well in regulating different functions in plant maturation. Interestingly, no systematical study has been conducted in durum wheat (Triticum turgidum subsp. durum). In the present study, 12 PR-1 genes encoding a CAP superfamily domain were identified in the genome of Triticum turgidum subsp. durum, which is an important cereal, using in silico approaches. Additionally, phylogenetic analysis showed that the PR-1 genes were classified into three groups based on their isoelectric point and the conserved motif domain. Moreover, our analysis showed that most of the TdPR-1 proteins presented an N-terminal signal peptide. Expression patterns analysis showed that the PR-1 gene family presented temporal and spatial specificity and was induced by different abiotic stresses. This is the first report describing the genome-scale analysis of the durum wheat PR-1 gene family, and these data will help further study the roles of PR-1 genes during stress responses, leading to crop improvement.

Molecular regulation of immunity in tea plants

Tea, which is mainly produced using the young leaves and buds of tea plants (Camellia sinensis (L.) O. Kuntze), is one of the most common non-alcoholic beverages consumed in the world. The standard of tea mostly depends on the variety and quality of tea plants, which generally grow in subtropical areas, where the warm and humid conditions are also conducive to the occurrence of diseases. In fighting against pathogens, plants rely on their sophisticated innate immune systems which has been extensively studied in model plants. Many components involved in pathogen associated molecular patterns (PAMPs) triggered immunity (PTI) and effector triggered immunity (ETI) have been found. Nevertheless, the molecular regulating network against pathogens (e.g., Pseudopestalotiopsis sp., Colletotrichum sp. and Exobasidium vexans) causing widespread disease (such as grey blight disease, anthracnose, and blister blight) in tea plants is still unclear. With the recent release of the genome data of tea plants, numerous genes involved in tea plant immunity have been identified, and the molecular mechanisms behind tea plant immunity is being studied. Therefore, the recent achievements in identifying and cloning functional genes/gene families, in finding crucial components of tea immunity signaling pathways, and in understanding the role of secondary metabolites have been summarized and the opportunities and challenges in the future studies of tea immunity are highlighted in this review.

Genome-wide analysis of WRKY transcription factor genes in Toona sinensis: An insight into evolutionary characteristics and terpene synthesis

WRKY transcription factors (TFs), one of the largest TF families, serve critical roles in the regulation of secondary metabolite production. However, little is known about the expression pattern of WRKY genes during the germination and maturation processes of Toona sinensis buds. In the present study, the new assembly of the T. sinensis genome was used for the identification of 78 TsWRKY genes, including gene structures, phylogenetic features, chromosomal locations, conserved protein domains, cis-regulatory elements, synteny, and expression profiles. Gene duplication analysis revealed that gene tandem and segmental duplication events drove the expansion of the TsWRKYs family, with the latter playing a key role in the creation of new TsWRKY genes. The synteny and evolutionary constraint analyses of the WRKY proteins among T. sinensis and several distinct species provided more detailed evidence of gene evolution for TsWRKYs. Besides, the expression patterns and co-expression network analysis show TsWRKYs may multi-genes co-participate in regulating terpenoid biosynthesis. The findings revealed that TsWRKYs potentially play a regulatory role in secondary metabolite synthesis, forming the basis for further functional characterization of WRKY genes with the intention of improving T. sinensis.

Genomic Survey of Heat Shock Proteins in Liriodendron chinense Provides Insight into Evolution, Characterization, and Functional Diversities

Heat shock proteins (HSPs) are conserved molecular chaperones whose main role is to facilitate the regulation of plant growth and stress responses. The HSP gene family has been characterized in most plants and elucidated as generally stress-induced, essential for their cytoprotective roles in cells. However, the HSP gene family has not yet been analyzed in the Liriodendron chinense genome. In current study, 60 HSP genes were identified in the L. chinense genome, including 7 LchiHSP90s, 23 LchiHSP70s, and 30 LchiHSP20s. We investigated the phylogenetic relationships, gene structure and arrangement, gene duplication events, cis-acting elements, 3D-protein structures, protein-protein interaction networks, and temperature stress responses in the identified L. chinense HSP genes. The results of the comparative phylogenetic analysis of HSP families in 32 plant species showed that LchiHSPs are closely related to the Cinnamomum kanehirae HSP gene family. Duplication events analysis showed seven segmental and six tandem duplication events that occurred in the LchiHSP gene family, which we speculated to have played an important role in the LchiHSP gene expansion and evolution. Furthermore, the Ka/Ks analysis indicated that these genes underwent a purifying selection. Analysis in the promoter region evidenced that the promoter region LchiHSPs carry many stress-responsive and hormone-related cis-elements. Investigations in the gene expression patterns of the LchiHSPs using transcriptome data and the qRT-PCR technique indicated that most LchiHSPs were responsive to cold and heat stress. In total, our results provide new insights into understanding the LchiHSP gene family function and their regulatory mechanisms in response to abiotic stresses.

Effects of exogenous calcium on the drought response of the tea plant (Camellia sinensis (L.) Kuntze)

Background

Drought is one of the major factors reducing the yield of many crops worldwide, including the tea crop (Camellia sinensis (L.) Kuntze). Calcium participates in most of cellular signaling processes, and its important role in stress detection and triggering a response has been shown in many crops. The aim of this study was to evaluate possible effects of calcium on the tea plant response to drought.

Methods

Experiments were conducted using 3-year-old potted tea plants of the best local cultivar Kolkhida. Application of ammonium nitrate (control treatment) or calcium nitrate (Ca treatment) to the soil was performed before drought induction. Next, a 7-day drought was induced in both groups of plants. The following physiological parameters were measured: relative electrical conductivity, pH of cell sap, and concentrations of cations, sugars, and amino acids. In addition, relative expression levels of 40 stress-related and crop quality-related genes were analyzed.

Results

Under drought stress, leaf electrolyte leakage differed significantly, indicating greater damage to cell membranes in control plants than in Ca-treated plants. Calcium application resulted in greater pH of cell sap; higher accumulation of tyrosine, methionine, and valine; and a greater Mg²⁺ content as compared to control plants. Drought stress downregulated most of the quality-related genes in both groups of tea plants. By contrast, significant upregulation of some genes was observed, namely CRK45, NAC26, TPS11, LOX1, LOX6, Hydrolase22, DREB26, SWEET2, GS, ADC, DHN2, GOLS1, GOLS3, and RHL41. Among them, three genes (LOX1, RHL41, and GOLS1) showed 2-3 times greater expression in Ca-treated plants than in control plants. Based on these results, it can be speculated that calcium affects galactinol biosynthesis and participates in the regulation of stomatal aperture not only through activation of abscisic-acid signaling but also through jasmonic-acid pathway activation. These findings clarify calcium-mediated mechanisms of drought defense in tree crops. Thus, calcium improves the drought response in the tea tree.

Research advances in function and regulation mechanisms of plant small heat shock proteins (sHSPs) under environmental stresses

Plants respond to various stresses by triggering the expression of genes that encode proteins involved in plant growth, fruit ripening, cellular protein homeostasis, and tolerance systems. sHSPs, a subfamily of heat shock proteins (HSPs), can be expressed in plants to inhibit abnormal aggregation of proteins and protect normal proteins by interacting with folding target proteins, protect cell integrity, and improve resistance under various adverse conditions. Thus, sHSPs have significant influences on seed germination and plant development. In this review, the classification, structure, and functions of sHSP family members in plants are systematically summarized, with emphasis on their roles in promoting fruit ripening and plant growth by reducing the accumulation of ROS, improving the survival rate of plants and the antioxidant activity, and protecting photosynthesis under biotic and abiotic stresses. Meanwhile, the production and regulatory mechanisms of sHSPs are described in detail. Heat shock factors, long non-coding RNA (lncRNAs), microRNA (miRNAs), and FK506 binding proteins are related to the production process of sHSPs. Molecular chaperone complex HSP70/100, plastidic proteins, and abscisic acid (ABA) are involved in the regulatory mechanisms of sHSPs. Besides, scientific efforts and practices for improving plant stress resistance have carried out the constitutive expression of sHSPs in transgenic plants in recent years. It is a powerful path for inducing the protective mechanisms of plants under various stresses. Therefore, exploring the role of sHSPs in the plant defense system paves a way for comprehensively unraveling plant tolerance in response to biotic and abiotic stress.

Genome-Wide Analyses of Tea Plant Stress-Associated Proteins (SAPs) Reveal the Role of CsSAP12 in Increased Drought Tolerance in Transgenic Tomatoes

Plant stress-associated proteins (SAPs) contain A20/AN1 zinc finger domains and are involved in plant response to abiotic stresses. In this study, we aimed to explore the biological function of tea plant CsSAPs. A total of 14 CsSAP genes were identified in the tea plant genome using a reference genome database (Camellia sinensis var. sinensis). The CsSAPs were divided into the following two groups: Group I, containing one AN1 domain and/or one A20 domain; and Group II, containing two AN1 domains and/or two C2H2 domains. The sequence alignments and conserved domains analysis indicated that the CsSAPs were highly structurally conserved in terms of amino acid sequence and protein structure. The CsSAPs showed different transcript levels in spatio-temporal expression and in response to cold and drought stress in tea plants. Furthermore, the expression of CsSAP12 was considerably upregulated under drought stress. The overexpression of CsSAP12 in transgenic tomatoes showed increased tolerance to drought stress compared with the wild type. Altogether, the results showed that CsSAP12 might be involved in drought stress. Thus, CsSAP12 might be a target gene in genetic engineering to improve drought tolerance in tea plants.

Overexpression of MET4 Leads to the Upregulation of Stress-Related Genes and Enhanced Sulfite Tolerance in Saccharomyces uvarum

Saccharomyces uvarum is one of the few fermentative species that can be used in winemaking, but its weak sulfite tolerance is the main reason for its further use. Previous studies have shown that the expression of the methionine synthase gene (MET4) is upregulated in FZF1 (a gene encoding a putative zinc finger protein, which is a positive regulator of the transcription of the cytosolic sulfotransferase gene SSU1) overexpression transformant strains, but its exact function is unknown. To gain insight into the function of the MET4 gene, in this study, a MET4 overexpression vector was constructed and transformed into S. uvarum strain A9. The MET4 transformants showed a 20 mM increase in sulfite tolerance compared to the starting strain. Ninety-two differential genes were found in the transcriptome of A9-MET4 compared to the A9 strain, of which 90 were upregulated, and two were downregulated. The results of RT-qPCR analyses confirmed that the expression of the HOMoserine requiring gene (HOM3) in the sulfate assimilation pathway and some fermentation-stress-related genes were upregulated in the transformants. The overexpression of the MET4 gene resulted in a significant increase in sulfite tolerance, the upregulation of fermentation-stress-related gene expression, and significant changes in the transcriptome profile of the S. uvarum strain.

Habanero pepper (Capsicum chinense) adaptation to water-deficit stress in a protected agricultural system

Drought is one of the major factors limiting global crop yield. In Mexico, agriculture is expected to be severely affected by drought. The Capsicum genus has several crop species of agricultural importance. In this work, we analysed the Capsicum chinense plant physiological responses and differentially expressed genes under water stress mainly focused on the responses elicited following recovery through repetitive stress. Plants were cultivated in an experimental block. Each block consisted of plants under water deficit and a control group without deficit. Morphometric and functional parameters, and the expression of genes related to resistance to abiotic stresses were measured. Morphological differences were observed. Plants subjected to water deficit showed impaired growth. Nonetheless, in the physiological parameters, no differences were observed between treatments. We selected abiotic stress-related genes that include heat-shock proteins (HSPs), heat-shock factors (HSFs), transcription factors related to abiotic stress (MYB, ETR1 , and WRKY ), and those associated with biotic and abiotic stress responses (Jar1 and Lox2 ). HSF, HSP, MYB72, ETR1, Jar1, WRKYa , and Lox2 genes were involved in the response to water-deficit stress in C. chinense plants. In conclusion, our work may improve our understanding of the morphological, physiological, and molecular mechanisms underlying hydric stress response in C. chinense .

Genome-Wide Characterization and Expression Analysis of Pathogenesis-Related 1 (PR-1) Gene Family in Tea Plant (Camellia sinensis (L.) O. Kuntze) in Response to Blister-Blight Disease Stress

Pathogenesis-related 1 (PR-1) proteins, which are defense proteins in plant–pathogen interactions, play an important role in the resistance and defense of plants against diseases. Blister blight disease is caused by Exobasidium vexans Massee and a major leaf disease of tea plants (Camellia sinensis (L.) O. Kuntze). However, the systematic characterization and analysis of the PR-1 gene family in tea plants is still lacking, and the defense mechanism of this family remains unknown. In this study, 17 CsPR-1 genes were identified from the tea plant genome and classified into five groups based on their signal peptide, isoelectric point, and C-terminus extension. Most of the CsPR-1 proteins contained an N-terminal signal peptide and a conserved PR-1 like domain. CsPR-1 genes comprised multiple cis-acting elements and were closely related to the signal-transduction pathways involving TCA, NPR1, EDS16, BGL2, PR4, and HCHIB. These characteristics imply an important role of the genes in the defense of the tea plant. In addition, the RNA-seq data and real-time PCR analysis demonstrated that the CsPR-1-2, -4, -6, -7, -8, -9, -10, -14, -15, and -17 genes were significantly upregulated under tea blister-blight stress. This study could help to increase understanding of CsPR-1 genes and their defense mechanism in response to tea blister blight.

Genome-Wide Identification and Characterization of HSP70 Gene Family in Aquilaria sinensis (Lour.) Gilg

The heat shock protein 70 (HSP70) gene family perform a fundamental role in protecting plants against biotic and abiotic stresses. Aquilaria sinensis is a classic stress-induced medicinal plant, producing a valuable dark resin in a wood matrix, known as agarwood, in response to environmental stresses. The HSP70 gene family has been systematic identified in many plants, but there is no comprehensive analysis at the genomic level in A. sinensis. In this study, 15 putative HSP70 genes were identified in A. sinensis through genome-wide bioinformatics analysis. Based on their phylogenetic relationships, the 15 AsHSP70 were grouped into six sub-families that with the conserved motifs and gene structures, and the genes were mapped onto six separate linkage groups. A qRT-PCR analysis showed that the relative expression levels of all the AsHSP70 genes were up-regulated by heat stress. Subcellular localization of all HSP70s was predicted, and three were verified by transiently expressed in Arabidopsis protoplasts. Based on the expression profiles in different tissues and different layers treated with Agar-Wit, we predict AsHSP70 genes are involved in different stages of agarwood formation. The systematic identification and expression analysis of HSP70s gene family imply some of them may play important roles in the formation of agarwood. Our findings not only provide a foundation for further study their biological function in the later research in A. sinensis, but also provides a reference for the analysis of HSPs in other species.

Genome-Wide Identification of Hsp90 Gene Family in Perennial Ryegrass and Expression Analysis under Various Abiotic Stresses

The heat shock protein 90 (Hsp90) is a protein produced in plants in response to stress. This study identified and analyzed Hsp90 gene family members in the perennial ryegrass genome. From the results, eight Hsp90 proteins were obtained and their MW, pI and number of amino acid bases varied. The amino acid bases ranged from 526 to 862. The CDS also ranged from 20 (LpHsp0-4) to 1 (LpHsp90-5). The least number of CDS regions was 1 (LpHsp90-5) with 528 kb amino acids, while the highest was 20 (LpHsp90-4) with 862 kb amino acids, which showed diversity among the protein sequences. The phylogenetic tree revealed that Hsp90 genes in Lolium perenne, Arabidopsis thaliana, Oryza sativa and Brachypodium distachyon could be divided into two groups with five paralogous gene pairs and three orthologous gene pairs. The expression analysis after perennial ryegrass was subjected to heat, salt, chromium (Cr), cadmium (Cd), polyethylene glycol (PEG) and abscisic acid (ABA) revealed that LpHsp90 genes were generally highly expressed under heat stress, but only two LpHsp90 proteins were expressed under Cr stresses. Additionally, the expression of the LpHsp90 proteins differed at each time point in all treatments. This study provides the basis for an understanding of the functions of LpHsp90 proteins in abiotic stress studies and in plant breeding.

Genome-wide identification of small heat shock protein (HSP20) homologs in three cucurbit species and the expression profiles of CsHSP20s under several abiotic stresses

Small heat shock protein (HSP20) genes play important roles in biological processes of plants. In this study, a total of 47 CsHSP20 genes, 45 CmHSP20 genes, and 47 ClHSP20 genes were genome-wide identified by 'hmmsearch' and BLASTP using the latest versions of cucumber, melon, and watermelon genomes, respectively. According to the phylogenetic relationships and predicted subcellular localizations, HSP20s of these three cucurbit species were divided into 8 subfamilies (CI-CIV, CP, ER, M, and PX), in which some HSP20s were closely related with each other based on the collinearity analysis. Specific expression patterns of CsHSP20s were checked in 10 different tissues of cucumber plants. RNA-seq analysis of transcript levels, combined with cis-acting elements and GO enrichment analysis suggested that CsHSP20s were responsive to several different types of abiotic stresses, including chilling, temperature and photoperiod, high temperature and high humidity, and salinity. In conclusion, results of this work not only provided valuable information for exploring the regulating mechanisms of CsHSP20s in responding to abiotic stresses in cucumber, but also shed light on the potentially evolutional relations among cucumber, melon, and watermelon from a perspective of comparative genomics that specified on HSP20 gene families.

In Silico Study of the RSH (RelA/SpoT Homologs) Gene Family and Expression Analysis in Response to PGPR Bacteria and Salinity in Brassica napus

Among several mechanisms involved in the plant stress response, synthesis of guanosine tetra and pentaphosphates (alarmones), homologous to the bacterial stringent response, is of crucial importance. Plant alarmones affect, among others, photosynthetic activity, metabolite accumulation, and nutrient remobilization, and thus regulate plant growth and development. The plant RSH (RelA/SpoT homolog) genes, that encode synthetases and/or hydrolases of alarmones, have been characterized in a limited number of plant species, e.g., Arabidopsis thaliana, Oryza sativa, and Ipomoea nil. Here, we used dry-to-wet laboratory research approaches to characterize RSH family genes in the polyploid plant Brassica napus. There are 12 RSH genes in the genome of rapeseed that belong to four types of RSH genes: 6 RSH1, 2 RSH2, 3 RSH3, and 1 CRSH. BnRSH genes contain 13-24 introns in RSH1, 2-6 introns in RSH2, 1-6 introns in RSH3, and 2-3 introns in the CRSH genes. In the promoter regions of the RSH genes, we showed the presence of regulatory elements of the response to light, plant hormones, plant development, and abiotic and biotic stresses. The wet-lab analysis showed that expression of BnRSH genes is generally not significantly affected by salt stress, but that the presence of PGPR bacteria, mostly of Serratia sp., increased the expression of BnRSH significantly. The obtained results show that BnRSH genes are differently affected by biotic and abiotic factors, which indicates their different functions in plants.

Genetic identification and characterization of chromosomal regions for kernel length and width increase from tetraploid wheat

BACKGROUND

Improvement of wheat gercTriticum aestivum L.) yield could relieve global food shortages. Kernel size, as an important component of 1000-kernel weight (TKW), is always a significant consideration to improve yield for wheat breeders. Wheat related species possesses numerous elite genes that can be introduced into wheat breeding. It is thus vital to explore, identify, and introduce new genetic resources for kernel size from wheat wild relatives to increase wheat yield.

RESULTS

In the present study, quantitative trait loci (QTL) for kernel length (KL) and width (KW) were detected in a recombinant inbred line (RIL) population derived from a cross between a wild emmer accession 'LM001' and a Sichuan endemic tetraploid wheat 'Ailanmai' using the Wheat 55 K single nucleotide polymorphism (SNP) array-based constructed linkage map and phenotype from six different environments. We identified eleven QTL for KL and KW including two major ones QKL.sicau-AM-3B and QKW.sicau-AM-4B, the positive alleles of which were from LM001 and Ailanmai, respectively. They explained 17.57 to 44.28% and 13.91 to 39.01% of the phenotypic variance, respectively. For these two major QTL, Kompetitive allele-specific PCR (KASP) markers were developed and used to successfully validate their effects in three F3 populations and two natural populations containing a panel of 272 Chinese wheat landraces and that of 300 Chinese wheat cultivars, respectively. QKL.sicau-AM-3B was located at 675.6-695.4 Mb on chromosome arm 3BL. QKW.sicau-AM-4B was located at 444.2-474.0 Mb on chromosome arm 4BL. Comparison with previous studies suggested that these two major QTL were likely new loci. Further analysis indicated that the positive alleles of QKL.sicau-AM-3B and QKW.sicau-AM-4B had a great additive effect increasing TKW by 6.01%. Correlation analysis between KL and other agronomic traits showed that KL was significantly correlated to spike length, length of uppermost internode, TKW, and flag leaf length. KW was also significantly correlated with TKW. Four genes, TRIDC3BG062390, TRIDC3BG062400, TRIDC4BG037810, and TRIDC4BG037830, associated with kernel development were predicted in physical intervals harboring these two major QTL on wild emmer and Chinese Spring reference genomes.

CONCLUSIONS

Two stable and major QTL for KL and KW across six environments were detected and verified in three biparental populations and two natural populations. Significant relationships between kernel size and yield-related traits were identified. KASP markers tightly linked the two major QTL could contribute greatly to subsequent fine mapping. These results suggested the application potential of wheat related species in wheat genetic improvement.

RNA-Seq analysis reveals potential regulators of programmed cell death and leaf remodelling in lace plant (Aponogeton madagascariensis)

BACKGROUND

The lace plant (Aponogeton madagascariensis) is an aquatic monocot that develops leaves with uniquely formed perforations through the use of a developmentally regulated process called programmed cell death (PCD). The process of perforation formation in lace plant leaves is subdivided into several developmental stages: pre-perforation, window, perforation formation, perforation expansion and mature. The first three emerging "imperforate leaves" do not form perforations, while all subsequent leaves form perforations via developmentally regulated PCD. PCD is active in cells called "PCD cells" that do not retain the antioxidant anthocyanin in spaces called areoles framed by the leaf veins of window stage leaves. Cells near the veins called "NPCD cells" retain a red pigmentation from anthocyanin and do not undergo PCD. While the cellular changes that occur during PCD are well studied, the gene expression patterns underlying these changes and driving PCD during leaf morphogenesis are mostly unknown. We sought to characterize differentially expressed genes (DEGs) that mediate lace plant leaf remodelling and PCD. This was achieved performing gene expression analysis using transcriptomics and comparing DEGs among different stages of leaf development, and between NPCD and PCD cells isolated by laser capture microdissection.

RESULTS

Transcriptomes were sequenced from imperforate, pre-perforation, window, and mature leaf stages, as well as PCD and NPCD cells isolated from window stage leaves. Differential expression analysis of the data revealed distinct gene expression profiles: pre-perforation and window stage leaves were characterized by higher expression of genes involved in anthocyanin biosynthesis, plant proteases, expansins, and autophagy-related genes. Mature and imperforate leaves upregulated genes associated with chlorophyll development, photosynthesis, and negative regulators of PCD. PCD cells were found to have a higher expression of genes involved with ethylene biosynthesis, brassinosteroid biosynthesis, and hydrolase activity whereas NPCD cells possessed higher expression of auxin transport, auxin signalling, aspartyl proteases, cysteine protease, Bag5, and anthocyanin biosynthesis enzymes.

CONCLUSIONS

RNA sequencing was used to generate a de novo transcriptome for A. madagascariensis leaves and revealed numerous DEGs potentially involved in PCD and leaf remodelling. The data generated from this investigation will be useful for future experiments on lace plant leaf development and PCD in planta.

[Comparative analysis of gene expression in tea plant (Camellia sinensis (L.) Kuntze) under low-temperature stress]

Низкотемпературный стресс – один из главных факторов, ограничивающих распространение и снижающих урожайность многих субтропических культур, в том числе и чая. Для эффективной селекции чая на устойчивость к морозу необходимо выявить генетические особенности ответа на холод у устойчивых генотипов и найти маркеры для определения доноров устойчивости в коллекциях. В настоящей работе про- веден сравнительный анализ экспрессии 18 генов (ICE1, CBF1, DHN1, DHN2, DHN3, NAC17, NAC26, NAC30, bHLH7, bHLH43, P5CS, WRKY2, LOX1, LOX6, LOX7, SnRK1.1, SnRK1.2, SnRK1.3), вовлеченных в абиотический стрессовый ответ у двух контрастных по устойчивости генотипов чая в условиях холода и мороза. Низкотемператур- ный стресс индуцировали путем помещения растений в холодильные камеры и снижением температуры до 0…+2 °С на семь дней (холодовой стресс) с последующим снижением температуры до –4…–6 °С на пять дней (промораживание). Кондуктометрическим методом измеряли электропроводность тканей листа, в ре- зультате чего были подтверждены различия по признаку устойчивости у двух исследуемых генотипов чая: холодовое воздействие не приводило к изменению электропроводности тканей листа, но после промора- живания этот показатель возрастал в большей степени у неустойчивого генотипа. Методом qRT-PCR анализи- ровали относительный уровень экспрессии генов на фоне референсного гена актина. При индукции стресса показана повышенная экспрессия всех исследуемых генов. У устойчивого генотипа чая выявлен ряд генов, более активно экспрессирующихся по сравнению с неустойчивым генотипом: ICE1, CBF1, DHN2, NAC17, NAC26, bHLH43, WRKY2, P5CS, LOX6, SnRK1.1, SnRK1.3. Эти гены могут быть маркерами устойчивости для поиска доно- ров в коллекциях геноресурсов. Показано, что у устойчивого генотипа чая экспрессия генов холодового от- вета начинается уже на стадии акклиматизации. Для дальнейших исследований комплексной устойчивости растений к низкотемпературному стрессу актуальным является изучение экспрессии этих генов в других органах чайного растения (побегах, корнях) при разной силе низкотемпературного воздействия.

Genome-Wide Characterization of HSP90 Gene Family in Cucumber and Their Potential Roles in Response to Abiotic and Biotic Stresses

Heat shock protein 90 (HSP90) possesses critical functions in plant developmental control and defense reactions. The HSP90 gene family has been studied in various plant species. However, the HSP90 gene family in cucumber has not been characterized in detail. In this study, a total of six HSP90 genes were identified from the cucumber genome, which were distributed to five chromosomes. Phylogenetic analysis divided the cucumber HSP90 genes into two groups. The structural characteristics of cucumber HSP90 members in the same group were similar but varied among different groups. Synteny analysis showed that only one cucumber HSP90 gene, Csa1G569290, was conservative, which was not collinear with any HSP90 gene in Arabidopsis and rice. The other five cucumber HSP90 genes were collinear with five Arabidopsis HSP90 genes and six rice HSP90 genes. Only one pair of paralogous genes in the cucumber HSP90 gene family, namely one pair of tandem duplication genes (Csa1G569270/Csa1G569290), was detected. The promoter analysis showed that the promoters of cucumber HSP90 genes contained hormone, stress, and development-related cis-elements. Tissue-specific expression analysis revealed that only one cucumber HSP90 gene Csa3G183950 was highly expressed in tendril but low or not expressed in other tissues, while the other five HSP90 genes were expressed in all tissues. Furthermore, the expression levels of cucumber HSP90 genes were differentially induced by temperature and photoperiod, gibberellin (GA), downy mildew, and powdery mildew stimuli. Two cucumber HSP90 genes, Csa1G569270 and Csa1G569290, were both differentially expressed in response to abiotic and biotic stresses, which means that these two HSP90 genes play important roles in the process of cucumber growth and development. These findings improve our understanding of cucumber HSP90 family genes and provide preliminary information for further studies of cucumber HSP90 gene functions in plant growth and development.

Comparative Expression Analysis of Stress-Inducible Candidate Genes in Response to Cold and Drought in Tea Plant [Camellia sinensis (L.) Kuntze]

Cold and drought are two of the most severe threats affecting the growth and productivity of the tea plant, limiting its global spread. Both stresses cause osmotic changes in the cells of the tea plant by decreasing their water potential. To develop cultivars that are tolerant to both stresses, it is essential to understand the genetic responses of tea plant to these two stresses, particularly in terms of the genes involved. In this study, we combined literature data with interspecific transcriptomic analyses (using Arabidopsis thaliana and Solanum lycopersicum) to choose genes related to cold tolerance. We identified 45 stress-inducible candidate genes associated with cold and drought responses in tea plants based on a comprehensive homologous detection method. Of these, nine were newly characterized by us, and 36 had previously been reported. The gene network analysis revealed upregulated expression in ICE1-related cluster of bHLH factors, HSP70/BAM5 connected genes (hexokinases, galactinol synthases, SnRK complex, etc.) indicating their possible co-expression. Using qRT-PCR we revealed that 10 genes were significantly upregulated in response to both cold and drought in tea plant: HSP70, GST, SUS1, DHN1, BMY5, bHLH102, GR-RBP3, ICE1, GOLS1, and GOLS3. SnRK1.2, HXK1/2, bHLH7/43/79/93 were specifically upregulated in cold, while RHL41, CAU1, Hydrolase22 were specifically upregulated in drought. Interestingly, the expression of CIP was higher in the recovery stage of both stresses, indicating its potentially important role in plant recovery after stress. In addition, some genes, such as DHN3, bHLH79, PEI54, SnRK1.2, SnRK1.3, and Hydrolase22, were significantly positively correlated between the cold and drought responses. CBF1, GOLS1, HXK2, and HXK3, by contrast, showed significantly negative correlations between the cold and drought responses. Our results provide valuable information and robust candidate genes for future functional analyses intended to improve the stress tolerance of the tea plant and other species.

Biochemical and Genetic Responses of Tea (Camellia sinensis (L.) Kuntze) Microplants under Mannitol-Induced Osmotic Stress In Vitro

Osmotic stress is a major factor reducing the growth and yield of many horticultural crops worldwide. To reveal reliable markers of tolerant genotypes, we need a comprehensive understanding of the responsive mechanisms in crops. In vitro stress induction can be an efficient tool to study the mechanisms of responses in plants to help gain a better understanding of the physiological and genetic responses of plant tissues against each stress factor. In the present study, the osmotic stress was induced by addition of mannitol into the culture media to reveal biochemical and genetic responses of tea microplants. The contents of proline, threonine, epigallocatechin, and epigallocatechin gallate were increased in leaves during mannitol treatment. The expression level of several genes, namely DHN2, LOX1, LOX6, BAM, SUS1, TPS11, RS1, RS2, and SnRK1.3, was elevated by 2–10 times under mannitol-induced osmotic stress, while the expression of many other stress-related genes was not changed significantly. Surprisingly, down-regulation of the following genes, viz. bHLH12, bHLH7, bHLH21, bHLH43, CBF1, WRKY2, SWEET1, SWEET2, SWEET3, INV5, and LOX7, was observed. During this study, two major groups of highly correlated genes were observed. The first group included seven genes, namely CBF1, DHN3, HXK2,SnRK1.1, SPS, SWEET3, and SWEET1. The second group comprised eight genes, viz. DHN2, SnRK1.3, HXK3, RS1, RS2,LOX6, SUS4, and BAM5. A high level of correlation indicates the high strength connection of the genes which can be co-expressed or can be linked to the joint regulons. The present study demonstrates that tea plants develop several adaptations to cope under osmotic stress in vitro; however, some important stress-related genes were silent or downregulated in microplants.

Genome-wide analysis of HSP90 gene family in the Mediterranean olive (Olea europaea subsp. europaea) provides insight into structural patterns, evolution and functional diversity

Plants regularly experience multiple abiotic and biotic pressures affecting their normal development. The 90-kDa heat shock protein (HSP90) plays a dynamic role in countering abiotic and biotic stresses via a plethora of functional mechanisms. The HSP90 has been investigated in many plant species. However, there is little information available about this gene family in the cultivated Mediterranean olive tree, Olea europaea subsp. europaea var. europaea. In the current study, we systematically performed genome-wide identification and characterization of the HSP90 gene family in O. europaea var. europaea (OeHSP90s). Twelve regular OeHSP90s were identified, which were phylogenetically grouped into two major clusters and four sub-clusters, showing five paralogous gene pairs evolving under purifying selection. All of the 12 proteins contained a Histidine kinase-like ATPase (HATPase_c) domain, justifying the role played by HSP90 proteins in ATP binding and hydrolysis. The predicted 3D structure of OeHSP90 proteins provided information to understand their functions at the biochemical level. Consistent with their phylogenetic relationships, OeHSP90 members were predicted to be localized in different cellular compartments, suggesting their involvement in various subcellular processes. In consonance with their spatial organization, olive HSP90 family members were found to share similar motif arrangements and similar number of exons. We found that OeHSP90 promoters contained various cis-acting elements associated with light responsiveness, hormone signaling pathways and reaction to various stress conditions. In addition, expression sequence tags (ESTs) analysis offered a view of OeHSP90 tissue- and developmental stage specific pattern of expression. Proteins interacting with OeHSP90s were predicted and their potential roles were discussed. Overall, our results offer premises for further investigation of the implication of HSP90 genes in the physiological processes of the olive and its adaptation to stresses.

Physiological, biochemical and genetic responses of Caucasian tea (Camellia sinensis (L.) Kuntze) genotypes under cold and frost stress

Background

Cold and frost are two serious factors limiting the yield of many crops worldwide, including the tea plant (Camellia sinensis (L.) Kuntze). The acclimatization of tea plant from tropical to temperate climate regions resulted in unique germplasm in the North–Western Caucasus with extremely frost-tolerant genotypes.

Methods

The aim of the current research was to evaluate the physiological, biochemical and genetic responses of tolerant and sensitive tea cultivars exposed to cold (0 to +2 °C for 7 days) and frost (−6 to −8 °C for 5 days). Relative water content, cell membranes integrity, pH of the cell sap, water soluble protein, cations, sugars, amino acids were measured under cold and frost. Comparative expression of the following genes ICE1, CBF1, WRKY2, DHN1, DHN2, DHN3, NAC17, NAC26, NAC30, SnRK1.1, SnRK1.2, SnRK1.3, bHLH7, bHLH43, P5CS, LOX1, LOX6, LOX7 were analyzed.

Results

We found elevated protein (by 3–4 times) and cations (potassium, calcium and magnesium) contents in the leaves of both cultivars under cold and frost treatments. Meanwhile, Leu, Met, Val, Thr, Ser were increased under cold and frost, however tolerant cv. Gruzinskii7 showed earlier accumulation of these amino acids. Out of 18 studied genes, 11 were expressed at greater level in the frost- tolerant cultivar comparing with frost-sensitive one: ICE1, CBF1, WRKY2, DHN2, NAC17, NAC26, SnRK1.1, SnRK1.3, bHLH43, P5CS and LOX6. Positive correlations between certain amino acids namely, Met, Thr, Leu and Ser and studied genes were found. Taken together, the revealed cold responses in Caucasian tea cultivars help better understanding of tea tolerance to low temperature stress and role of revealed metabolites need to be further evaluated in different tea genotypes.

Characterization and Analysis of the Full-Length Transcriptomes of Multiple Organs in Pseudotaxus chienii (W.C.Cheng) W.C.Cheng

Pseudotaxus chienii, a rare tertiary relict species with economic and ecological value, is a representative of the monotypic genus Pseudotaxus that is endemic to China. P. chienii can adapt well to habitat isolation and ecological heterogeneity under a variety of climate and soil conditions, and is able to survive in harsh environments. However, little is known about the molecular and genetic resources of this long-lived conifer. Herein, we sequenced the transcriptomes of four organs of P. chienii using the PacBio Isoform Sequencing and Illumina RNA Sequencing platforms. Based on the PacBio Iso-Seq data, we obtained 44,896, 58,082, 50,485, and 67,638 full-length unigenes from the root, stem, leaf, and strobilus, respectively, with a mean length of 2692 bp, and a mean N50 length of 3010.75 bp. We then comprehensively annotated these unigenes. The number of organ-specific expressed unigenes ranged from 4393 in leaf to 9124 in strobilus, suggesting their special roles in physiological processes, organ development, and adaptability in the different four organs. A total of 16,562 differentially expressed genes (DEGs) were identified among the four organs and clustered into six subclusters. The gene families related to biotic/abiotic factors, including the TPS, CYP450, and HSP families, were characterized. The expression levels of most DEGs in the phenylpropanoid biosynthesis pathway and plant–pathogen interactions were higher in the root than in the three other organs, suggesting that root constitutes the main organ of defensive compound synthesis and accumulation and has a stronger ability to respond to stress. The sequences were analyzed to predict transcription factors, long non-coding RNAs, and alternative splicing events. The expression levels of most DEGs of C2H2, C3H, bHLH, and bZIP families in the root and stem were higher than those in the leaf and strobilus, indicating that these TFs may play a crucial role in the survival of the root and stem. These results comprise the first comprehensive gene expression profiles obtained for different organs of P. chienii. Our findings will facilitate further studies on the functional genomics, adaptive evolution, and phylogeny of P. chienii, and lay the foundation for the development of conservation strategies for this endangered conifer.

Detection of superoxide dismutase (Cu-Zn) isoenzymes in leaves and pseudobulbs of Bulbophyllum morphologlorum Kraenzl orchid by comparative proteomic analysis

Typically, biological systems are protected from the toxic effect of free radicals by antioxidant defense. Extracts from orchids have been reported to show high levels of exogenous antioxidant activity including Bulbophyllum orchids but so far, there have been no reports on antioxidant enzymes. Therefore, differences in protein expression from leaves and pseudobulbs of Bulbophyllum morphologlorum Kraenzl and Dendrobium Sonia Earsakul were studied using two-dimensional gel electrophoresis and mass spectrometry (LC/MS/MS). Interestingly, the largest group of these stress response proteins were associated with antioxidant defense and temperature stress, including superoxide dismutase (Cu–Zn) and heat shock protein 70. The high expression of this antioxidant enzyme from Bulbophyllum morphologlorum Kraenzl was confirmed by activity staining on native-PAGE, and the two Cu/Zn-SODs isoenzymes were identified as Cu/Zn-SOD 1 and Cu/Zn-SOD 2 by LC/MS/MS. The results suggested that Bulbophyllum orchid can be a potential plant source for medicines and natural antioxidant supplements.

Genes underlying cold acclimation in the tea plant (<i>Camellia sinensis</i> (L.) Kuntze)

The article reviews the latest studies showing the diversity of genetic mechanisms and gene families underlying the increased cold and frost tolerance of tea and other plant species. It has been shown that cell responses to chilling (0…+15°C) and freezing (< 0°C) are not the same and gene expression under cold stress is genotype-specific. In recent decades, progress has been made in understanding the genetic mechanisms underlying the cold response of plants – ICE1 (inducer of CBF expression 1), CBF (C-repeat-binding factor), COR (cold-regulated genes) pathways and signaling have been discovered. The ICE, CBF and DHN gene groups play a key role in the cold acclimation of the tea plant. The accumulation of CBF transcripts occurs after 15 min of chilling induction, and longer cold stress leads to accumulation of CBF transcripts. It is shown that the transcripts of the CsDHN1, CsDHN2 and CsDHN3 genes accumulate at a higher level in resistant genotypes of tea in comparison with susceptible cultivars during freezing. CBF-independent pathways include genes involved in metabolism and transcription factors such as HSFC1, ZAT12, CZF1, PLD (phospholipase D), WRKY, HD-Zip, CsLEA, LOX, NAC, HSP, which are widely distributed in plants and are involved in the basic mechanisms of tea resistance to cold and frost. The most recent studies show an important role of miRNA in the mechanisms of response to chilling and freezing in tea. The data obtained on different plant species may correlate with the mechanisms of frost tolerance of tea and are the basis for future studies of the signaling pathways of response to cold in the tea plant. The results of the research emphasize the need to further explore the ways in which various genes regulate the tolerance of tea to cold stress to find the molecular markers of frost tolerance.

Heat Shock Proteins: Dynamic Biomolecules to Counter Plant Biotic and Abiotic Stresses

Due to the present scenario of climate change, plants have to evolve strategies to survive and perform under a plethora of biotic and abiotic stresses, which restrict plant productivity. Maintenance of plant protein functional conformation and preventing non-native proteins from aggregation, which leads to metabolic disruption, are of prime importance. Plant heat shock proteins (HSPs), as chaperones, play a pivotal role in conferring biotic and abiotic stress tolerance. Moreover, HSP also enhances membrane stability and detoxifies the reactive oxygen species (ROS) by positively regulating the antioxidant enzymes system. Additionally, it uses ROS as a signal to molecules to induce HSP production. HSP also enhances plant immunity by the accumulation and stability of pathogenesis-related (PR) proteins under various biotic stresses. Thus, to unravel the entire plant defense system, the role of HSPs are discussed with a special focus on plant response to biotic and abiotic stresses, which will be helpful in the development of stress tolerance in plant crops.

Increased expression of heat shock protein (HSP) 10 and HSP70 correlates with poor prognosis of nasopharyngeal carcinoma

BACKGROUND

Heat shock proteins (HSPs) are a large family of chaperones implicating in occurrence and progression of tumor. In our previous study, we found HSP10 correlates with poor prognosis of oral squamous cell carcinoma and astrocytoma. HSP70 is also an important part of this family and whether the alterations of HSP10 and HSP70 expression and their common expression correlates with carcinogenesis and progression of nasopharyngeal carcinoma (NPC) has not been reported.

METHOD

In this study, we investigate the correlation between the expression of HSP10 and HSP70 and clinicopathological characteristics in NPC by immunohistochemistry (IHC).

RESULTS

Results indicated that positive expression of HSP10 and HSP70 was higher in NPC tissues (both P<0.001). Positive expression of HSP10 and HSP70 proteins, and common positive expression of the two HSPs analyzed in advanced clinical stages were higher than that in early clinical stages (All P<0.05). There was significantly higher expression of HSP10, HSP70, and common expression in NPC with LNM (lymph node metastasis) compared with NPC without LNM (All P<0.05). Interestingly, positive expression of HSP10 and HSP70 proteins and common expression had an evidently inverse correlation with survival status (All P<0.05). Spearman's correlation analysis showed expression of HSP10 was positively associated with HSP70 (r=0.407, P<0 0.001). Kaplan-Meier analysis showed that the overall survival rates for NPC patients with positive expression of HSP10 and HSP70 and common expression were significantly lower than these patients with negative expression (All P<0.05). Furthermore, positive expression of HSP10 and HSP70 proteins was identified as independent poor prognostic factors for NPC patients (both P<0.05) by Cox regression analysis.

CONCLUSION

 In conclusion, HSP10 and HSP70 can serve as the poor prognostic factors for NPC patients.

Impact assessment of major abiotic stresses on the proteome profiling of some important crop plants: a current update

Abiotic stresses adversely affect the plant's growth and development leading to loss of crop plants and plant products in terms of both the quality and quantity. Two main strategies are adopted by plants to acclimatize to stresses; avoidance and tolerance. These adaptive strategies of plants at the cellular and metabolic level enable them to withstand such detrimental conditions. Acclimatization is associated with intensive changes in the proteome of plants and these changes are directly involved in plants response to stress. Proteome studies can be used to screen for these proteins and their involvement in plants response to various abiotic stresses evaluated. In this review, proteomic studies of different plants species under different abiotic stresses, particularly drought, salinity, heat, cold, and waterlogging, are discussed. From different proteomic studies, the stress response can be determined by an interaction between proteomic and physiological changes which occur in plants during such stress conditions. These identified proteins from different processes under different abiotic stress conditions definitely add to our understanding for exploiting them in various biotechnological applications in crop improvement.

The ER Lumenal Hsp70 Protein FpLhs1 Is Important for Conidiation and Plant Infection in Fusarium pseudograminearum

Heat shock protein 70s (Hsp70s) are a class of molecular chaperones that are highly conserved and ubiquitous in organisms ranging from microorganisms to plants and humans. Hsp70s play key roles in cellular development and protecting living organisms from environmental stresses such as heat, drought, salinity, acidity, and cold. However, their functions in pathogenic fungi are largely unknown. Here, a total of 14 FpHsp70 genes were identified in Fusarium pseudograminearum, including 3 in the mitochondria, 7 in the cytoplasm, 2 in the endoplasmic reticulum (ER), 1 in the nucleus, and 1 in the plastid. However, the exon–intron boundaries and protein motifs of the FpHsp70 have no consistency in the same subfamily. Expression analysis revealed that most FpHsp70 genes were up-regulated during infection, implying that FpHsp70 genes may play important roles in F. pseudograminearum pathogenicity. Furthermore, knockout of an ER lumenal Hsp70 homolog FpLhs1 gene reduced growth, conidiation, and pathogenicity in F. pseudograminearum. These mutants also showed a defect in secretion of some proteins. Together, FpHsp70s might play essential roles in F. pseudograminearum and FpLhs1 is likely to act on the development and virulence by regulating protein secretion.

A Gene Regulatory Network Controlled by BpERF2 and BpMYB102 in Birch under Drought Conditions

Gene expression profiles are powerful tools for investigating mechanisms of plant stress tolerance. Betula platyphylla (birch) is a widely distributed tree, but its drought-tolerance mechanism has been little studied. Using RNA-Seq, we identified 2917 birch genes involved in its response to drought stress. These drought-responsive genes include the late embryogenesis abundant (LEA) family, heat shock protein (HSP) family, water shortage-related and ROS-scavenging proteins, and many transcription factors (TFs). Among the drought-induced TFs, the ethylene responsive factor (ERF) and myeloblastosis oncogene (MYB) families were the most abundant. BpERF2 and BpMYB102, which were strongly induced by drought and had high transcription levels, were selected to study their regulatory networks. BpERF2 and BpMYB102 both played roles in enhancing drought tolerance in birch. Chromatin immunoprecipitation combined with qRT-PCR indicated that BpERF2 regulated genes such as those in the LEA and HSP families, while BpMYB102 regulated genes such as Pathogenesis-related Protein 1 (PRP1) and 4-Coumarate:Coenzyme A Ligase 10 (4CL10). Multiple genes were regulated by both BpERF2 and BpMYB102. We further characterized the function of some of these genes, and the genes that encode Root Primordium Defective 1 (RPD1), PRP1, 4CL10, LEA1, SOD5, and HSPs were found to be involved in drought tolerance. Therefore, our results suggest that BpERF2 and BpMYB102 serve as transcription factors that regulate a series of drought-tolerance genes in B. platyphylla to improve drought tolerance.

HSP superfamily of genes in the malaria vector Anopheles sinensis: diversity, phylogenetics and association with pyrethroid resistance

BACKGROUND

Heat shock proteins (HSPs) are molecular chaperones that are involved in many normal cellular processes and various kinds of environmental stress. There is still no report regarding the diversity and phylogenetics research of HSP superfamily of genes at whole genome level in insects, and the HSP gene association with pyrethroid resistance is also not well known. The present study investigated the diversity, classification, scaffold location, characteristics, and phylogenetics of the superfamily of genes in Anopheles sinensis genome, and the HSP genes associated with pyrethroid resistance.

METHODS

The present study identified the HSP genes in the An. sinensis genome, analysed their characteristics, and deduced phylogenetic relationships of all HSPs in An. sinensis, Anopheles gambiae, Culex quinquefasciatus and Aedes aegypti by bioinformatic methods. Importantly, the present study screened the HSPs associated with pyrethroid resistance using three field pyrethroid-resistant populations with RNA-seq and RT-qPCR, and looked over the HSP gene expression pattern for the first time in An. sinensis on the time-scale post insecticide treatment with RT-qPCR.

RESULTS

There are 72 HSP genes in An. sinensis genome, and they are classified into five families and 11 subfamilies based on their molecular weight, homology and phylogenetics. Both RNA-seq and qPCR analysis revealed that the expression of AsHSP90AB, AsHSP70-2 and AsHSP21.7 are significantly upregulated in at least one field pyrethroid-resistant population. Eleven genes are significantly upregulated in different period after pyrethroid exposure. The HSP90, sHSP and HSP70 families are proposed to be involved in pyrethroid stress response based in expression analyses of three field pyrethroid-resistant populations, and expression pattern on the time scale post insecticide treatment. The AsHSP90AB gene is proposed to be the essential HSP gene for pyrethroid stress response in An. sinensis.

CONCLUSIONS

This study provides the information frame for HSP superfamily of genes, and lays an important basis for the better understanding and further research of HSP function in insect adaptability to diverse environments.