Dehydrin Expression Research Articles

Role of Trichoderma asperelloides and Trichoderma brevicompactum in improving drought tolerance in rice

Drought is considered as one of the major abiotic stresses affecting rice production under rainfed ecologies of Bangladesh hampering the country's self-sufficiency in rice production through reduced crop yield and quality. In the present study, we studied the effect of two species of plant growth promoting Trichoderma v iz; Trichoderma asperelloides and Trichoderma brevicompactum on rice plant development under drought stress and their role in inducing tolerance to drought at physiological and biochemical level. Results reveal that both species are capable of inducing plant tolerance to drought stress when tested on drought tolerant (BRRI dhan56) and drought susceptible (IR64) varieties. As the number of drought stress days increased, there was an increase in root length of both the varieties but increase in root length was more in BRRI dhan56 as compared to IR 64 when seeds of both varieties were primed with Trichoderma. There was significant change in proline, malondialdehyde (MDA), total Phenolic content (TFC), H2O2 content in Trichoderma treated versus non-treated plants for both varieties. These biochemical changes were verified with the expression of aquaporin (AQU), dehydrin (DHN) and DREB genes in both rice varieties treated with both Trichoderma species. Interaction studies of Trichoderma species with two rice genotypes suggested that AQU-2 expressed more in tolerant variety (BRRI dhan56) when primed with Trichoderma asperelloides whereas, both Trichoderma spp. up regulated the expression of DHN-4 and DREB genes in both rice genotypes under drought conditions. The present findings suggest that the both Trichoderma asperelloides and Trichoderma brevicompactum are most effective in improving drought tolerance in rice, and its prospective application will contribute to the advancement of rice genotypes to sustain crop productivity under drought stress.

Biochemical, physiological, and molecular responses of diverse olive cultivars to different irrigation regimes

Olive is an essential industrial crop in the Mediterranean region with valuable economic and agricultural concerns. Despite its drought resistance, its productivity is restricted by extreme drought stress. Olive cultivars display considerable variation in response mechanisms to drought stress. Accordingly, the impact of mild and extreme water deprivation over two seasons compared to full irrigation requirements on growth and physiological characteristics of three diverse olive cultivars. Three olive cultivars, ‘Manzanillo’, ‘Eggizi-Shami’, and ‘Tofaahi’, were evaluated under three irrigation regimes 100% ETc, 75% ETc, and 50% ETc. Characteristics of shoot and root, as well as physio-chemical constituents, were determined. Besides, the gene expression of dehydration-responsive element binding (DREB), dehydrin (DHN), and catalase (CAT) genes in olive cultivars were explored under different irrigation regimes. The results indicated a substantial impact of irrigation level on all studied parameters. The mild and extreme drought stress treatments caused a gradual reduction in nitrogen, phosphorus, and potassium content, relative water content, root and shoot length, root and leaf numbers, branch count, and leaf area across both seasons. Conversely, proline content was considerably increased under drought treatments compared to well-watered conditions. Similarly, the assessed cultivars exhibited significant variation in all studied parameters, with ‘Eggizi-Shami’ demonstrating superiority. Under mild and extreme drought stress conditions, the cultivar ‘Eggizi-Shami’ displayed the highest proline content and most growth characteristics. Besides, the real-time quantitative PCR (RT-qPCR) analysis displayed significant alterations in gene expression of the tested three genes related to drought response (DHN, DREB, and CAT). The RT-qPCR analysis revealed that under drought stress conditions (75% and 50% ETc), ‘Eggizi-Shami’ exhibited higher expression compared to the other two cultivars (‘Tofaahi’ and ‘Manzanillo’). Combining the results of morphological and physiological parameters with gene expression analysis of drought-related genes can offer highly validated information about drought-tolerant olive cultivars. This integrated approach serves as an innovative methodology to identify and confirm genes involved in abiotic stress.

Genetic determination of drought resistance in common wheat (Triticum aestivum L.)

The aim of the work is to analyze the literature data on genetic determinants and molecular mechanisms involved in the regulation of adaptation and resistance to drought in common wheat. Results. Regulation of the response to osmotic stress in common wheat is carried out through several abscisic acid-dependent or independent pathways. ABA inhibits the growth processes of aerial parts of the plant by inhibiting the action of auxins and cytokinins, increases the hydraulic conductivity of roots by modulating the activity of aquaporins - membrane water channels, changes the flow of ions in the closing cells of the stomata, which leads to their closure and a decrease in water consumption for transpiration. ABA activates a number of TFs that regulate the expression of genes, the products of which are necessary to eliminate the negative consequences of water deficit. ABA-dependent is activation of the genes of antioxidant defense enzymes - superoxide dismutase, peroxidase, catalase and enzymes of the ascorbate-glutathione cycle. Activators of their transcription are NAC, MYB, WRKY, NF-Y, ZFHD and TaERF3 TFs. Expression of LEA genes and dehydrins, which prevent protein aggregation due to dehydration, is ensured by both ABA-dependent and -independent signal transduction pathways, with the help of AREB/ABF, NAC, MYB, WRKY, AP2/EREBP and ZFHD TFs. ABA also activates the biosynthesis of proline - one of the main low-molecular osmoprotectants that accumulate in the cell and ensure the stability of its water regime. Osmolyte accumulation is regulated by MYB, WRKY, NF-Y and TaERF3 TFs. Conclusions. Thus, in the article is considered the regulatory role of ABA in the formation of drought resistance through molecular interactions involving aquaporins, dehydrins, SNRK2 protein kinases, LEA proteins and their genes, as well as genes of transcription factors NAC, MYB, WRKY, NF-Y, AP/ EREBP, ZFHD, DREB. However, due to the complexity of the wheat genome and the polygenicity of the drought resistance trait, there is currently no line of molecular genetic markers for certain alleles of drought resistance genes that would allow predicting the drought resistance of Ukrainian breeding varieties. The molecular genetic mechanisms underlying drought resistance and the identification of genes with the greatest phenotypic effect, as well as the modeling of the work of these genes at different stages of ontogenesis and the involvement of drought resistance alleles in breeding programs, currently require further research.

Physiological, Structural, and Functional Insights Into the Cryoprotection of Membranes by the Dehydrins.

Plants can be exposed to cold temperatures and have therefore evolved several mechanisms to prevent damage caused by freezing. One of the most important targets are membranes, which are particularly susceptible to cold damage. To protect against such abiotic stresses, plants express a family of proteins known as late embryogenesis abundant (LEA) proteins. Many LEA proteins are intrinsically disordered, that is, they do not contain stable secondary or tertiary structures alone in solution. These proteins have been shown in a number of studies to protect plants from damage caused by cold, drought, salinity, and osmotic stress. In this family, the most studied proteins are the type II LEA proteins, better known as dehydrins (dehydration-induced proteins). Many physiological studies have shown that dehydrins are often located near the membrane during abiotic stress and that the expression of dehydrins helps to prevent the formation of oxidation-modified lipids and reduce the amount of electrolyte leakage, two hallmarks of damaged membranes. One of the earliest biophysical clues that dehydrins are involved in membrane cryoprotection came from in vitro studies that demonstrated a binding interaction between the protein and membranes. Subsequent work has shown that one conserved motif, known as K-segments, is involved in binding, while recent studies have used NMR to explore the residue specific structure of dehydrins when bound to membranes. The biophysical techniques also provide insight into the mechanism by which dehydrins protect the membrane from cold stress, which appears to mainly involve the lowering of the transition temperature.

Physiological, Biochemical and Molecular Response of Different Winter Wheat Varieties under Drought Stress at Germination and Seedling Growth Stage

Due to climate change in recent years, there has been an increasing water deficit during the winter wheat sowing period. This study evaluated six Croatian winter wheat varieties’ physiological, biochemical, and molecular responses under two drought stress levels at the germination/seedling growth stage. Lipid peroxidation was mainly induced under both drought stress treatments, while the antioxidative response was variety-specific. The most significant role in the antioxidative response had glutathione along with the ascorbate-glutathione pathway. Under drought stress, wheat seedlings responded in proline accumulation that was correlated with the P5CS gene expression. Expression of genes encoding dehydrins (DHN5, WZY2) was highly induced under the drought stress in all varieties, while genes encoding transcription factors were differentially regulated. Expression of DREB1 was upregulated under severe drought stress in most varieties, while the expression of WRKY2 was downregulated or revealed control levels. Different mechanisms were shown to contribute to the drought tolerance in different varieties, which was mainly associated with osmotic adjustment and dehydrins expression. Identifying different mechanisms in drought stress response would advance our understanding of the complex strategies contributing to wheat tolerance to drought in the early growth stage and could contribute to variety selection useful for developing new drought-tolerant varieties.

Effect of drought stress on wheat (Triticum durum) growth and metabolism: insight from GABA shunt, reactive oxygen species and dehydrin genes expression.

Activation of γ-aminobutyric acid (GABA) shunt pathway and upregulation of dehydrins are involved in metabolic homeostasis and protective mechanisms against drought stress. Seed germination percentage, seedling growth, levels of GABA, alanine, glutamate, malondialdehyde (MDA), and the expression of glutamate decarboxylase (GAD ) and dehydrin (dhn and wcor ) genes were examined in post-germination and seedlings of four durum wheat (Triticum durum L.) cultivars in response to water holding capacity levels (80%, 50%, and 20%). Data showed a significant decrease in seed germination percentage, seedling length, fresh and dry weight, and water content as water holding capacity level was decreased. Levels of GABA, alanine, glutamate, and MDA were significantly increased with a negative correlation in post-germination and seedling stages as water holding capacity level was decreased. Prolonged exposure to drought stress increased the GAD expression that activated GABA shunt pathway especially at seedlings growth stage to maintain carbon/nitrogen balance, amino acids and carbohydrates metabolism, and plant growth regulation under drought stress. The mRNA transcripts of dhn and wcor significantly increased as water availability decreased in all wheat cultivars during the post-germination stage presumably to enhance plant tolerance to drought stress by cell membrane protection, cryoprotection of enzymes, and prevention of reactive oxygen species (ROS) accumulation. This study showed that the four durum wheat cultivars responded differently to drought stress especially during the seedling growth stage which might be connected with ROS scavenging systems and the activation of antioxidant enzymes that were associated with activation of GABA shunt pathway and the production of GABA in durum seedlings.

Comparative Genomics, Evolution, and Drought-Induced Expression of Dehydrin Genes in Model Brachypodium Grasses.

Dehydration proteins (dehydrins, DHNs) confer tolerance to water-stress deficit in plants. We performed a comparative genomics and evolutionary study of DHN genes in four model Brachypodium grass species. Due to limited knowledge on dehydrin expression under water deprivation stress in Brachypodium, we also performed a drought-induced gene expression analysis in 32 ecotypes of the genus’ flagship species B. distachyon showing different hydric requirements. Genomic sequence analysis detected 10 types of dehydrin genes (Bdhn) across the Brachypodium species. Domain and conserved motif contents of peptides encoded by Bdhn genes revealed eight protein architectures. Bdhn genes were spread across several chromosomes. Selection analysis indicated that all the Bdhn genes were constrained by purifying selection. Three upstream cis-regulatory motifs (BES1, MYB124, ZAT) were detected in several Bdhn genes. Gene expression analysis demonstrated that only four Bdhn1-Bdhn2, Bdhn3, and Bdhn7 genes, orthologs of wheat, barley, rice, sorghum, and maize genes, were expressed in mature leaves of B. distachyon and that all of them were more highly expressed in plants under drought conditions. Brachypodium dehydrin expression was significantly correlated with drought-response phenotypic traits (plant biomass, leaf carbon and proline contents and water use efficiency increases, and leaf water and nitrogen content decreases) being more pronounced in drought-tolerant ecotypes. Our results indicate that dehydrin type and regulation could be a key factor determining the acquisition of water-stress tolerance in grasses.

Plant Dehydrins: Expression, Regulatory Networks, and Protective Roles in Plants Challenged by Abiotic Stress.

Dehydrins, also known as Group II late embryogenesis abundant (LEA) proteins, are classic intrinsically disordered proteins, which have high hydrophilicity. A wide range of hostile environmental conditions including low temperature, drought, and high salinity stimulate dehydrin expression. Numerous studies have furnished evidence for the protective role played by dehydrins in plants exposed to abiotic stress. Furthermore, dehydrins play important roles in seed maturation and plant stress tolerance. Hence, dehydrins might also protect plasma membranes and proteins and stabilize DNA conformations. In the present review, we discuss the regulatory networks of dehydrin gene expression including the abscisic acid (ABA), mitogen-activated protein (MAP) kinase cascade, and Ca2+ signaling pathways. Crosstalk among these molecules and pathways may form a complex, diverse regulatory network, which may be implicated in regulating the same dehydrin.

Dehydrins and Soluble Sugars Involved in Cold Acclimation of Rosa wichurana and Rose Cultivar ‘Yesterday’

Rose is the most economically important ornamental plant. However, cold stress seriously affects the survival and regrowth of garden roses in northern regions. Cold acclimation was studied using two genotypes (Rosa wichurana and R. hybrida ‘Yesterday’) selected from a rose breeding program. During the winter season (November to April), the cold hardiness of stems, soluble sugar content, and expression of dehydrins and the related key genes in the soluble sugar metabolism were analyzed. ‘Yesterday’ is more cold-hardy and acclimated faster, reaching its maximum cold hardiness in December. R. wichurana is relatively less cold-hardy, only reaching its maximum cold hardiness in January after prolonged exposure to freezing temperatures. Dehydrin transcripts accumulated significantly during November–January in both genotypes. Soluble sugars are highly involved in cold acclimation, with sucrose and oligosaccharides significantly correlated with cold hardiness. Sucrose occupied the highest proportion of total soluble sugars in both genotypes. During November–January, downregulation of RhSUS was found in both genotypes, while upregulation of RhSPS was observed in ‘Yesterday’ and upregulation of RhINV2 was found in R. wichurana. Oligosaccharides accumulated from November to February and decreased to a significantly low level in April. RhRS6 had a significant upregulation in December in R. wichurana. This study provides insight into the cold acclimation mechanism of roses by combining transcription patterns with metabolite quantification.

Dehydrin in the past four decades: From chaperones to transcription co-regulators in regulating abiotic stress response

Abstract Dehydrins are a multifunctional and diverse class of proteins that are crucial in combating abiotic stresses imposed on the plant kingdom. Plants use dehydrin to stabilize biomolecules and membranes; therefore, dehydrins are key during dehydration stress. For almost 30 years, dehydrins have been known to be chaperones that enable ion-binding functions, act as a cryo-protectants and aid in free radical scavenging. Other functions of dehydrin have been explored more recently, and the results suggest that dehydrin might have roles beyond its chaperone functions. First, dehydrin has recently been found to regulate stress-responsive genes, and evolution has enabled dehydrins to participate in the cell’s transcription regulatory machinery during the stress response. Second, dehydrins have been reported to play an indirect role in histone modification. In this epigenetic process, H3K4me3 modification is positively associated with the expression of dehydrin and other drought-responsive genes. This review describes the details of studies on dehydrin from its discovery until 2021, thus providing a progressive, complex, interlinked and comprehensive understanding of the dehydrin gene family. In addition, biotechnologies and integrative approaches that have aided in exploring the varying dynamics of dehydrin spatially and temporally are discussed.

The dehydrins gene expression differs across ecotypes in Norway spruce and relates to weather fluctuations

Norway spruce has a broad natural distribution range, which results in a substantial variety of its physiological and genetic variation. There are three distinct altitudinal ecotypes described in this tree species. The physiological optimum of each ecotype may be shifted due to ongoing climate change, especially in traits associated with water demand that might be crucial for adaptation. Dehydrins are proteins that help to mitigate the adverse effects of dehydration. Dehydrin gene expression patterns appeared to be a suitable marker for plant stress assessment. Genetically determined differences in response between individuals and populations were formerly studied, however, mainly in controlled conditions. We evaluated ecotypic variation in dehydrin gene expression in a clonal bank comprised of all three ecotypes. A genetic relationship among targeted trees was uncovered utilizing GBS (Genotyping by Sequencing) platform. We sampled 4–6 trees of each ecotype throughout 15 months period. Subsequently, we assessed the RNA expression of dehydrin genes by qRT-PCR. For this study, we deliberately selected dehydrins from different categories. Our findings detected significant differences among ecotypes in dehydrin expression. The association of recorded climatic variables and individual gene expression across the study period was evaluated and revealed, for certain genes, a correlation between dehydrin gene expression and precipitation, temperature, and day-length.

Effects of Exogenous Salicylic Acid on Drought Response and Characterization of Dehydrins in Impatiens walleriana.

Impatiens walleriana is a valued ornamental plant sensitive to drought stress. We investigated whether the foliar application of 2mM salicylic acid (SA) can protect potted I. walleriana plants from drought stress. The plants were divided into: watered plants, drought-stressed plants, watered plants treated with SA and drought-stressed plants treated with SA. The number of flowers and flower buds, relative water content (RWC), contents of malondialdehyde (MDA) and proline (Pro) and the activities of superoxide dismutases, catalases and peroxidases were recorded at different time points. Three dehydrin sequences were identified in de novo assembled leaf transcriptome: IwDhn1, IwDhn2.1 and IwDhn2.2. Drought stress caused wilting, floral abortion, reduction of RWC and increased MDA—an indicator of lipid peroxidation. In response to drought, Impatiens accumulated Pro and induced chloroplastic Cu/ZnSOD and two peroxidase isoforms. The most remarkable drought response was strong induction of IwDhn2.1 and IwDhn2.2. Rehydration restored RWC, Pro level, Cu/ZnSOD activity and dehydrins expression in drought-stressed plants approximately to the values of watered plants.SA had ameliorating effects on plants exposed to drought, including prevention of wilting, preservation of RWC, increased Pro accumulation, modulation of antioxidative activities and remarkable decrease of lipid peroxidation, but without effects on flowers’ preservation.

Distribution and Classification of Dehydrins in Selected Plant Species Using Bioinformatics Approach.

Background: Plant growth, reproduction and yields are severely damaged under adverse environmental stresses. These stresses can be either biotic or abiotic, and many stress related proteins are expressed in response to these stresses. Among these proteins dehydrins are reported to have a role primarily in the abiotic stresses. Dehydrins are very diverse proteins and a uniform annotation system is needed for their functional characterization in the future research.Objectives: The aim of the present work is to identify, classify and analyze the expression of dehydrin proteins under different biotic and abiotic stresses in the selected plant species by using different computational tools.Materials and Methods: Prosite database is used for dehydrin proteins identification, and to conform the location of conserved motifs in selected plant species. The dehydrins extracted from uniprot database were annotated, based on the ensemble plant gene id. Subcellular localization was predicted using PSI predictor tool. Dehydrin expression analyses were retrieved form the genevestigator tool.Results: Dehydrins were annotated on the basis of dehydrin gene locus and conserved motifs available in different domain databases. Dehydrins were identified and annotated in Arabidopsis thaliana (13), Glycine max (12), Zea mays (05), Oryza sativa (11), Solanum tuberosum (05), Solanum lycopersicum (06), Triticum aestivum (32) and Vitis vinifera (06). It has been proposed that dehydrins are located primarily in cytosol and nucleus. Based on genevestigater expression analyses the plant species selected for this study contain all the classes of dehydrins, namely YnSKn, Kn, SKn, and YnKn; except class KnS. Conclusions: Dehydrins are diverse proteins and a uniform classification is introduced for their better characterization. The distribution of dehydrins in different tissues and developmental stages suggest an important function throughout plant growth cycle. It has also been concluded that dehydrins expressed particularly in drought, cold and salt stresses, and may have limited role in heat, anoxia, heavy-metal and biotic stresses as well.

Diffusions of sound frequencies designed to target dehydrins induce hydric stress tolerance in Pisum sativum seedings

Among plant responses to environmentally induced stress modulating protein expression appears to be a key stage in inducible signaling. Our study was focused on an innovative strategy to stimulate plant stress resistance, namely, the use of targeted sequences of specific sound frequencies.The influence of acoustic stimulation on plant protein synthesis was investigated. In our study green peas, Pisum sativum, were cultured under hydric stress conditions with targeted acoustic stimulation. Acoustic sequences targeting dehydrins (DHN) which accumulate in plants in response to dehydration were studied. We experimented on pea seeding with two different sequences of sounds: the first one corresponded to DHN cognate protein and the second one was aimed at the DHN consensus sequence. Shoot elongation after pea seed germination was estimated by fresh weight gain studied in the presence of various conditions of exposure to both sequences of sounds. DHN expression in peas was quantified via ELISA tests and Western-blotting by using specific antibodies.A significant increase in fresh weight in peas grown under exposure to the DHN cognate sound sequence was observed, whereas the consensus sound sequence had no effect on growth. Moreover, the 37kDa DHN amount was increased in peas treated with the consensus acoustic sequence. These results suggest that the expression of DHN could be specifically modulated by a designed acoustic stimulus.

Photosynthetic response and transcriptomic profiling provide insights into the alkali tolerance of clone halophyte Leymus chinensis

Alkali stress is one of the important factors in restricting agriculture production. Leymus chinensis is constructive halophyte species in alkalized grassland in China. In order to investigate the gene expression response of L. chinensis to alkali stress, we used PacBio technology to obtain reference full-length transcript sequences for transcriptomic analysis of alkali stress response. In order to elucidate the alkali tolerance mechanisms of L. chinensis, we measured the photosynthetic parameters, concentrations of ions and compatible solutes, chloroplast ultrastructure and anatomy of control and stressed plants. Our results showed that L. chinensis shares many alkali-tolerance mechanisms with glycophytes. Higher stability of photosynthetic apparatus under alkali stress may be prominent alkali-tolerance trait of L. chinensis. L. chinensis may have a strong capacity to decline the toxicity of Na+ to organelles and cytoplasmic proteins. Enhanced expression of dehydrin and LEA genes and increased accumulation of carbohydrates may contribute to the development of Na+-specific stress tolerance of L. chinensis under alkali stress.

Transcription factor TabHLH49 positively regulates dehydrin WZY2 gene expression and enhances drought stress tolerance in wheat

BackgroundAs functional proteins, dehydrins are found in many maturing seeds and vegetable tissues under adverse environmental conditions. However, the regulation of dehydrin expression remains unclear.ResultsIn this study, a novel drought stress-related bHLH transcription factor, TabHLH49, was isolated from a wheat cDNA library treated with the drought and cold stress by using yeast one-hybrid system. TabHLH49 protein possesses a typical conserved bHLH domain and is a Myc-type bHLH transcription factor. TabHLH49 was detected in the nucleus of tobacco epidermal cells, and the amino acid sequences at the C-terminus (amino acids 323–362) is necessary for its transactivation activity. Real-time PCR analyses revealed the tissue-specific expression and drought stress-responsive expression of TabHLH49 in wheat. In addition, the verification in Y1H and electrophoretic mobility shift assays illustrated that TabHLH49 protein can bind and interact with the promoter of the wheat WZY2 dehydrin. Furthermore, the dual-luciferase assays showed that TabHLH49 can positively regulate the expression of WZY2 dehydrin. The transient expression and BSMV-mediated gene silencing of TabHLH49 also showed that TabHLH49 positively regulates the expression of WZY2 dehydrin and improves drought stress resistance in wheat.ConclusionsThese results provide direct evidences that TabHLH49 positively regulates expression level of dehydrin WZY2 gene and improves drought tolerance of wheat.

Differential responses of antioxidants and dehydrin in two Switchgrass (Panicum virgatum L.) cultivars contrasting in drought tolerance

Abstract Drought stress is a major limiting factor for plant growth and development in many regions of the world. This study was designed to investigate antioxidant metabolism and dehydrin expression responses to drought stress in two switchgrass cultivars (drought tolerant Alamo, and drought sensitive Dacotah) contrasting in drought tolerance. The plants were subjected to well-watered [100% evapotranspiration (ET)] or drought stress (30%-50% ET) conditions for up to 24 d in growth chambers. Drought stress decreased leaf relative water content (RWC), increased leaf electrolyte leakage (EL), leaf malondialdehyde (MDA) content in two cultivars, but Alamo exhibited higher leaf RWC level, lower leaf EL and MDA when compared to Dacotah at 24 d of drought treatment. Drought stress also increased superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities in two cultivars, Alamo had relatively higher SOD, CAT and APX activities and greater abundance of SOD and APX isozymes than Dacotah at 24 d of drought treatment. Alamo had higher abundance of 55 KDa and 18 KDa dehydrin accumulation than Dacotah under drought treatment. Relative genes expression level of PvCAT1, PvAPX2, PvERD and PvPIP1;5 in Alamo were significantly higher than Dacotah at 24 d of drought treatment. These results suggest that increase in antioxidant enzymes and accumulation of dehydrin were highly related with switchgrass drought tolerance. Antioxidant enzyme activity, isozyme expression and dehydrin abundance could provide a useful screening tool to identify relative drought tolerance in switchgrass cultivars.

Identification of upstream transcription factors and an interacting PP2C protein of dehydrin WZY2 gene in wheat

ABSTRACTAs functional proteins dehydrins are found in many maturing seeds and vegetable tissue under adverse environmental conditions. However, the regulation of dehydrin expression remains unclear.To explore regulatory mechanisms of wheat dehydrin WZY2 expression under abiotic stresses, we constructed a cDNA library from PEG- and cold-treated wheat seedlings and performed yeast one-hybrid assay and yeast two-hybrid assay to identify the upstream transcription factors and protein interacting with dehydrin WZY2 gene. Yeast one-hybrid assay illustrated that bHLH49-like (GenBank NO. XM_020296294), zinc finger A20 and AN1 domain-containing stress-associated protein 6-like (GenBank NO. XM_020341647), and bHLH47-like (GenBank NO. XM_020313116) proteins can bind and interact with the promoter of the WZY2, these sequences are Aegilops tauschii transcription factors, the diploid progenitor of the D genome of hexaploid wheat (Triticum aestivum, genomes AABBDD). Real-time PCR analyzes unraveled the stress responsive expression of XM_020296294, XM_020341647, and XM_020313116 in wheat. XM_020296294 and XM_020341647 showed a similar expression patterns with WZY2. Yeast two-hybrid assay indicated that PP2C (GenBank NO. XM_020293398) protein can interact with WZY2. These results provided evidences that WZY2 could be positively regulated by XM_020296294 and XM_020341647 transcription factors, and WZY2 may also play an important role in the ABA signaling pathway through interaction with PP2C to regulate stress-responsive genes expression in wheat. The obtained results contribute for provide a better understanding of the regulatory mechanism of dehydrin expression under abiotic stresses in wheat.

Transcriptome Analysis and Differential Expression in Tall Fescue Harboring Different Endophyte Strains in Response to Water Deficit

Two tall fescue [Lolium arundinaceum (Schreb.) Darbysh. = Schedonorus arundinaceus (Schreb.) Dumort. = Festuca arundinacea var. arundinacea Schreb.] plant genotypes with an Epichloë coenophiala (Morgan-Jones & W. Gams) C.W. Bacon & Schardl common toxic endophyte (CTE), one with a nontoxic strain (NTE19) and one with another Epichloë species (FaTG-4) were evaluated and compared with their respective endophyte-free clones for responses to water-deficit stress in the greenhouse. One of the plant genotypes (P27) showed a positive effect of its CTE strain on tiller production after stress and resumed watering. In transcriptome analysis of the pseudostems (leaf sheath whorls), differentially expressed genes (DEGs) were defined as having at least twofold expression difference and false discovery rate (FDR) < 0.05 in comparisons of water treatment (stressed or watered), endophyte presence or absence, or both. Stress affected 38% of the plant transcripts including those for the expected stress-response pathways. The DEGs affected by endophyte in stressed plants were unique to individual plant genotypes. In unstressed plants, endophyte presence tended to reduce expression of genes putatively for defense against fungi, but in unstressed P27 endophyte presence there was enhanced expression of dehydrin and heat shock protein genes. Our results indicated subtle and variable effects of endophytes on tall fescue gene expression; where the endophyte confers protection, its effects on plant gene expression may help prime the plant for stress resistance.

Dehydrin Content in Fresh and Desiccated Pistachio (Pistacia vera L.) Seeds

Seeds may desiccate after independence from parent plant and remain in a dry inactive state until the conditions for germination are conducive. Dehydrin proteins pattern and expression in mature pistachio seeds were surveyed at fresh and 48-h desiccated states by western blot method, using an antibody against conserved K-segment. Mature seeds lost 92.4% moisture after desiccation without any loss in complete germinability. Five dehydrin bands were detected in both cotyledon and embryonic axis. At fresh state, 23, 25, and 48 kDa bands had a lower content in cotyledon than in axis, but increased to an equal level by desiccation. The 32 and 39 kDa bands were detected only in fresh stage, preferentially in cotyledons, and disappeared after desiccation; therefore, they have other roles rather than dehydration protection. Some bands of 17, 19, 20, 28, 67, 77 and 98 kDa were detected only in axes at both states. Among them, the 28 kDa band was only used for densitometry and was not stimulated by dehydration. Further studies are required to establish the exact role of dehydrins which do not have a role in dehydration tolerance.