ABA Stress Research Articles

Genome-wide identification and expression analysis of the GRAS family proteins in Medicago truncatula

The GRAS gene family performs a variety of functions in plant growth and development processes, and they also play essential roles in plant response to environmental stresses. Medicago truncatula is a diploid plant with a small genome used as a model organism. Despite the vital role of GRAS genes in plant growth regulation, few studies on these genes in M. truncatula have been conducted to date. Using the M. truncatula reference genome data, we identified 68 MtGRAS genes, which were classified into 16 groups by phylogenetic analysis, located on eight chromosomes. The structure analysis indicated that MtGRAS genes retained a relatively constant exon–intron composition during the evolution of the M. truncatula genome. Most of the closely related members in the phylogenetic tree had similar motif compositions. Different motifs distributed in different groups of the MtGRAS genes were the sources of their functional divergence. Twenty-eight MtGRAS genes were expressed in six tissues, namely root, bud, blade, seedpod, nodule, and flower tissues, suggesting their putative function in many aspects of plant growth and development. Nine MtGRAS genes were upregulated under cold, freezing, drought, ABA, and salt stress treatments, indicating that they play vital roles in the response to abiotic stress in M. truncatula. Our study provides valuable information that can be utilized to improve the quality and agronomic benefits of M. truncatula and other plants.

RBM25 Mediates Abiotic Responses in Plants.

Alternative splicing (AS) of pre-mRNAs is one of the most important post-transcriptional regulations that enable a single gene to code for multiple proteins resulting in the biodiversity of proteins in eukaryotes. Recently, we have shown that an Arabidopsis thaliana RNA recognition motif-containing protein RBM25 is a novel splicing factor to modulate plant response to ABA during seed germination and post-germination through regulating HAB1 pre-mRNA AS. Here, we show that RBM25 is preferentially expressed in stomata and vascular tissues in Arabidopsis and is induced by ABA and abiotic stresses. Loss-of-function mutant is highly tolerant to drought and sensitive to salt stress. Bioinformatic analysis and expression assays reveal that Arabidopsis RBM25 is induced by multiple abiotic stresses, suggesting a crucial role of RBM25 in Arabidopsis responses to adverse environmental conditions. Furthermore, we provide a comprehensive characterization of the homologous genes of Arabidopsis RBM25 based on the latest plant genome sequences and public microarray databases. Fourteen homologous genes are identified in different plant species which show similar structure in gene and protein. Notably, the promoter analysis reveals that RBM25 homologs are likely controlled by the regulators involved in multiple plant growth and abiotic stresses, such as drought and unfavorable temperature. The comparative analysis of general and unique cis regulatory elements of the RBM25 homologs highlights the conserved and unique molecular processes that modulate plant response to abiotic stresses through RBM25-mediated alternative splicing.

Triticum aestivum WRAB18 functions in plastids and confers abiotic stress tolerance when overexpressed in Escherichia coli and Nicotiania benthamiana.

WRAB18, an ABA-inducible protein belongs to the third family of late embryogenesis abundant (LEA) proteins which can be induced by different biotic or abiotic stresses. In the present study, WRAB18 was cloned from the Zhengyin 1 cultivar of Triticum aestivum and overexpressed in Escherichia coli to explore its effects on the growth of E. coli under different abiotic stresses. Results suggested the enhanced exhibition of tolerance of E. coli to these stresses. Meanwhile, the WRAB18-transgenic tobacco plants were obtained to analyze the stress-related enzymatic activities of ascorbate peroxidase (APX), peroxidase (POD) and superoxide dismutase (SOD), and to quantify the content of malonaldehyde (MDA) under osmotic stress, high salinity, and low and high temperature stress. The activities of APX, POD and SOD in the transgenic tobacco lines were higher while the content of MDA was lower than those of WT lines. Moreover, plastid localization of WRAB18 in Nicotiana benthamiana plasma cells were found fusing with GFP. In addition, purified WRAB18 protein protected LDH (Lactate dehydrogenase) enzyme activity in vitro from various stress conditions. In brief, WRAB18 protein shows protective action behaving as a “molecular shield” in both prokaryotic and eukaryotic cells under various abiotic stresses, not only during ABA stress.

Overexpression of persimmon DkXTH1 enhanced tolerance to abiotic stress and delayed fruit softening in transgenic plants.

DkXTH1 promoted cell elongation and more strength to maintain structural integrity by involving in cell wall assembly, thus enhanced tolerance to abiotic stress with broader phenotype in transgenic plants. Xyloglucan endotransglucosylase/hydrolase (XTH) is thought to play a key role in cell wall modifications by cleaving and re-joining xyloglucan, and participates in the diverse physiological processes. DkXTH1 was found to peak in immature expanding persimmon fruit, and its higher expression level exhibited along with firmer fruit during storage. In the present study, transgenic Arabidopsis and tomato plants were generated with DkXTH1 constitutively expressed. Overexpression of DkXTH1 enhanced tolerance to salt, ABA and drought stresses in transgenic Arabidopsis plants with respect to root and leaf growth, and survival. Transgenic tomatoes collected at the mature green stage, presented delayed fruit softening coupled with postponed color change, a later and lower ethylene peak, and higher firmness in comparison with the wild-type tomatoes during storage. Furthermore, broader leaves and tomato fruit with larger diameter were gained in transgenic Arabidopsis and tomato, respectively. Most importantly, transgenic plants exhibited more large and irregular cells with higher density of cell wall and intercellular spaces, resulting from the overactivity of XET enzymes involving in cell wall assembly. We suggest that DkXTH1 expression resulted in cells with more strength and thickness to maintain structural integrity, and thus enhanced tolerance to abiotic stress and delayed fruit softening in transgenic plants.

Genome-wide identification and expression profiling of copper-containing amine oxidase genes in sweet orange (Citrus sinensis)

Copper-containing amine oxidases (CuAOs) play important roles in polyamine catabolism and function in plant development and abiotic stresses response. In this study, eight putative CuAO genes (CsCuAO1–CsCuAO8), distributed on three chromosomes, were identified in sweet orange (Citrus sinensis Osbeck) genome. They were divided into two major groups according to the phylogenetic analysis. The CsCuAOs possess typically conserved 33 amino acid residues and contain either a C-terminal peroxisomal targeting peptide or an N-terminal signal. Transcript levels of the CsCuAOs were detected in leaf, stem cotyledon, and root, but tissue-specific expression pattern was observed. Many putative cis-elements involved in hormone and stress response were predicted in a 1.5-kb promoter region of the CsCuAOs. The CsCuAOs were significantly induced by exogenous polyamines, including putrescine, spermidine, and spermine. ABA and various abiotic stresses (cold, salt, and osmotic shock) down-regulated most of the CsCuAOs, whereas CsCuAO3 and CsCuAO7 were up-regulated. Transient expression assay demonstrate that CsCuAO2 was involved in putrescine catabolism. Taken together, these findings provide valuable knowledge for better understanding of the potential biological functions of CuAO genes in polyamine catabolism of sweet orange.

Functional Characterization of Cotton GaMYB62L, a Novel R2R3 TF in Transgenic Arabidopsis.

Drought stress can trigger the production of ABA in plants, in response to adverse conditions, which induces the transcript of stress-related marker genes. The R2R3 MYB TFs are implicated in regulation of various plants developmental, metabolic and multiple environmental stress responses. Here, a R2R3-MYB cloned gene, GaMYB62L, was transformed in Arabidopsis and was functionally characterized. The GaMYB62L protein contains two SANT domains with a conserved R2R3 imperfect repeats. The GaMYB62L cDNA is 1,017 bp with a CDS of 879, encodes a 292-residue polypeptide with MW of 38.78 kD and a pI value of 8.91. Overexpressed GaMYB62L transgenic Arabidopsis have increased proline and chlorophyll content, superior seed germination rate under salt and osmotic stress, less water loss rate with reduced stomatal apertures, high drought avoidance as compared to WT on water deprivation and also significant plant survival rates at low temperature. In addition, overexpressed GaMYB62L lines were more sensitive to ABA mediated germination and root elongation assay. Moreover, ABA induced GaMYB62L overexpression, enhanced the expression of ABA stress related marker genes like RD22, COR15A, ADH1, and RD29A. Together, overexpression of GaMYB62L suggested having developed better drought, salt and cold tolerance in transgenic Arabidopsis and thus presented it as a prospective candidate gene to achieve better abiotic stress tolerance in cotton crop.

A Novel RNA-Binding Protein Involves ABA Signaling by Post-transcriptionally Repressing ABI2.

The Stress Associated RNA-binding protein 1 (SRP1) repressed by ABA, salt and cold encodes a C2C2-type zinc finger protein in Arabidopsis. The knock-out mutation in srp1 reduced the sensitivity of seed to ABA and salt stress during germination and post-germinative growth stages. In contrast, SRP1-overexpressing seedlings were more sensitive to ABA and salt compared to wild type plants. In the presence of ABA, the transcript levels of ABA signaling and germination-related genes including ABI3. ABI5. EM1 and EM6 were less induced in srp1 compared to WT. Interestingly, expression of ABI2 encoding a protein phosphatase 2C protein were significantly up-regulated in srp1 mutants. By in vitro analysis, SRP1 was identified as a novel RNA-binding protein directly binding to 3′UTR of ABI2 mRNA. Moreover, transient expression assay proved the function of SRP1 in reducing the activity of luciferase whose coding sequence was fused with the ABI2 3’UTR. Together, it is suggested that SRP1 is involved in the ABA signaling by post-transcriptionally repressing ABI2 expression in Arabidopsis.

Overexpression of Heteromeric GhACCase Subunits Enhanced Oil Accumulation in Upland Cotton

Acetyl-CoA carboxylase (ACCase) catalyzes acetyl-CoA to produce malonyl-CoA, which is the essential first step in the biosynthesis of de novo fatty acids. The heteromeric ACCase of higher plants, such as upland cotton, is composed of four subunits: biotin carboxyl carrier protein (BCCP), biotin carboxylase (BC), α-subunit of carboxyltransferase (CTα), and β-subunit of carboxyltransferase (CTβ). In this study, four subunits encoding heteromeric ACCase were amplified and the structures were analyzed further. The result showed that 7, 16, 10, and 1 exon(s) were identified from GhBCCP1, GhBC1, GhCTα2, and GhCTβ, respectively. The expression pattern analysis showed that the transcripts of these four subunits were ubiquitous in all the tested tissues and may have a positive correlation between the four subunits and oil accumulation. The four subunits coordinate to enhance oil content. The expression patterns and levels varied under ABA, MeJA treatments, and cold stress. Furthermore, under the control of a seed-specific AGP promoter, overexpression of the four subunits separately in Upland cotton demonstrated that GhBCCP1 transgenic plants showed a significant increase of 21.92% in oil content in cotton seeds, while about a 17% increase was noted for GhBC1 and GhCTβ, respectively. So overexpression of each subunit of heteromeric GhACCase may effectively increase seed oil content in Upland cotton.

The NAC-type transcription factor OsNAC2 regulates ABA-dependent genes and abiotic stress tolerance in rice

Plants can perceive environmental changes and respond to external stressors. Here, we show that OsNAC2, a member of the NAC transcription factor family, was strongly induced by ABA and osmotic stressors such as drought and high salt. With reduced yields under drought conditions at the flowering stage, OsNAC2 overexpression lines had lower resistance to high salt and drought conditions. RNAi plants showed enhanced tolerance to high salinity and drought stress at both the vegetative and flowering stages. Furthermore, RNAi plants had improved yields after drought stress. A microarray assay indicated that many ABA-dependent stress-related genes were down-regulated in OsNAC2 overexpression lines. We further confirmed that OsNAC2 directly binds the promoters of LATE EMBRYOGENESIS ABUNDANT 3 (OsLEA3) and Stress-Activated Protein Kinases 1 (OsSAPK1), two marker genes in the abiotic stress and ABA response pathways, respectively. Our results suggest that in rice OsNAC2 regulates both abiotic stress responses and ABA-mediated responses, and acts at the junction between the ABA and abiotic stress pathways.

Cloning and expression analysis of protein kinase SmSnRK2.4 from Salvia miltiorrhiza

Sucrose non-fermenting 1-related protein kinase 2(SnRK2) plays a key role in abiotic stress signaling in plants. In this study, we cloned a SmSnRK2.4 gene belonging to subclass I of SnRK2 from Salvia miltiorrhiza by screening its transcriptome database. The SmSnRK2.4 gene contains 8 introns and 9 exons, with a 1 068 bp open reading frame encoding a polypeptide of 355 amino acids, the predicted molecular mass of which is 40.63 kDa. Prokaryotic expression of SmSnRK2.4 protein using pMAL-c2X as the expression vector displayed that the recombinant protein of SmSnRK2.4 gene in E. coli was consistent with the predicted size. A 3 000 bp promoter sequence of SmSnRK2.4 contained some stress-responsive elements and hormone-responsive elements. Quantitative real-time PCR analysis revealed that the expression of SmSnRK2.4 in root was much higher than that in stem and leaf, SmSnRK2.4 was strongly induced by PEG stress, weakly induced by ABA stress. This research provided a basis for further study of the SmSnRK2.4 gene playing the role in accumulate mechanism of secondary metabolites in S. miltiorrhiza under drought.

A Novel Wheat Nicotianamine Synthase Gene, TaNAS-D, Confers High Salt Tolerance in Transgenic Arabidopsis

Nicotianamine synthase (NAS) plays a pivotal role in balancing the concentrations of heavy metals in plants, but its characteristics and functions in salt stress responses are not completely understood, particularly in wheat. In this study, the salt-induced gene TaNAS-D was cloned from wheat and characterized. TaNAS-D, localized throughout the cell, is mainly expressed in developed vascular bundle tissues and is responsive to NaCl, ABA, and H2O2 stresses. Overexpression of TaNAS-D in Arabidopsis led to elevated NA levels and enhanced salt stress tolerance, which was demonstrated by higher germination rates and improved growth of TaNAS-D transgenic Arabidopsis plants compared with WT when exposed to salt stress. Further investigation revealed that TaNAS-D transgenic Arabidopsis plants displayed higher K+/Na+ ratios, lower malondialdehyde (MDA) levels, and less ion leakage (IL) consistently accompanied by increased peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities, thereby reducing membrane injury. Moreover, TaNAS-D overexpression under salt stress increased AtSOS1, AtSOS2, AtSOS3, AtFAD5, and AtSAD1 transcript levels. These findings indicate that TaNAS-D plays a positive role in salt tolerance by improving the antioxidant defense system and upregulating salt overly sensitive (SOS) pathway genes.

The miR165/166 Mediated Regulatory Module Plays Critical Roles in ABA Homeostasis and Response in Arabidopsis thaliana.

The function of miR165/166 in plant growth and development has been extensively studied, however, its roles in abiotic stress responses remain largely unknown. Here, we report that reduction in the expression of miR165/166 conferred a drought and cold resistance phenotype and hypersensitivity to ABA during seed germination and post-germination seedling development. We further show that the ABA hypersensitive phenotype is associated with a changed transcript abundance of ABA-responsive genes and a higher expression level of ABI4, which can be directly regulated by a miR165/166 target. Additionally, we found that reduction in miR165/166 expression leads to elevated ABA levels, which occurs at least partially through the increased expression of BG1, a gene that is directly regulated by a miR165/166 target. Taken together, our results uncover a novel role for miR165/166 in the regulation of ABA and abiotic stress responses and control of ABA homeostasis.

Potato dehydrins present high intrinsic disorder and are differentially expressed under ABA and abiotic stresses

Dehydrins (DHNs) correspond to late embryogenesis abundant proteins (LEA) of group 2, they are known as glycin rich proteins. Despite their expression during the late seed maturation stages, they are also involved in plant response to a number of abiotic stresses such as drought, salinity and cold. In the present study, we identified five full-length cDNAs encoding dehydrins (designated StDHN2a, StDHN1, TAS14, StDHN25 and StLEA27) isolated from potato. These dehydrins were composed of serine amino acids called S domain and lysine-rich segment corresponding to a K domain. Three DHNs (StDHN1, TAS14 and StLEA27) contained Y segments. In silico analysis showed that these StDHN sequences share high homology with other Solanum dehydrin proteins species. The analysis of gene expression using quantitative RT-PCR showed that they were upregulated by dehydration and salinity. Moreover, the search for putative regulatory element in the promoter sequence of dehydrin genes was investigated.

Molecular characterization of maize bHLH transcription factor (ZmKS), a new ZmOST1 kinase substrate

In order to identify potential substrates of the maize kinase in the ABA signalling network, ZmOST1 was used as bait against a library of cDNAs from dehydrated young leaves. A ZmOST1-interactive polypeptide ZmKS (gene locus tag: GRMZM2G114873), showing homology with the Arabidopsis thaliana basic helix-loop-helix (bHLH) DNA-binding transcription factor was identified. Using a comparative genomic approach, the ZmKS corresponding protein was identified as conceptual translated bHLH transcription factor ABA-responsive kinase substrate. ZmKS is localized in the nucleus, shows a potential binding specificity preferentially detectable on cis-acting E-box like heptameric motifs CCACTTG and CAAGTTG, and is phosphorylated by maize protein kinase ZmOST1. ZmKS is expressed in embryo, leaf and root, expression being affected by ABA and osmotic stress. Transgenic Arabidopsis plants, with gain of ZmKS function, show a delay in germination and a transcriptional stomatal opening-facilitator activity, switchover upon ZmKS phosphorylation, suggesting that ZmKS is an ABA-repressed trans-acting activator.

Isolation and Characterization of ScGluD2, a New Sugarcane beta-1,3-Glucanase D Family Gene Induced by Sporisorium scitamineum, ABA, H2O2, NaCl, and CdCl2 Stresses.

Beta-1,3-glucanases (EC 3.2.1.39), commonly known as pathogenesis-related (PR) proteins, play an important role not only in plant defense against fungal pathogens but also in plant physiological and developmental processes. However, only a limited number of sugarcane beta-1,3-glucanase genes have been isolated. In the present study, we identified and characterized a new beta-1,3-glucanase gene ScGluD2 (GenBank Acc No. KF664181) from sugarcane. An X8 domain was present at the C terminal region of ScGluD2, suggesting beta-1,3-glucan-binding function. Phylogenetic analysis showed that the predicted ScGluD2 protein was classified into subfamily D beta-1,3-glucanase. Localization of the ScGluD2 protein in the plasma membrane was determined by tagging it with green fluorescent protein. The expression of ScGluD2 was more up-regulated in sugarcane smut-resistant cultivars in the early stage (1 or 3 days) than in the susceptible ones after being challenged by the smut pathogen, revealing that ScGluD2 may be involved in defense against the invasion of Sporisorium scitamineum. Transient overexpression of ScGluD2 in Nicotiana benthamiana leaves induced a defense response and exhibited antimicrobial action on the tobacco pathogens Pseudomonas solanacearum and Botrytis cinerea, further demonstrating that ScGluD2 was related to the resistance to plant pathogens. However, the transcripts of ScGluD2 partially increased (12 h) under NaCl stress, and were steadily up-regulated from 6 to 24 h upon ABA, H2O2, and CdCl2 treatments, suggesting that ABA may be a signal molecule regulating oxidative stress and play a role in the salt and heavy metal stress-induced stimulation of ScGluD2 transcripts. Taken together, ScGluD2, a novel member of subfamily D beta-1,3-glucanase, was a stress-related gene of sugarcane involved in plant defense against smut pathogen attack and salt and heavy metal stresses.

Identification and expression analysis of cytokinin response regulators in Fragaria vesca

Cytokinin response regulators (RRs) are important components of the two component signal systems, which are involved in the regulation of plant growth and development, and in the response to abiotic stress. In this study, 18 cytokinin RR genes were identified in Fragaria vesca through the genome-wide search. They were further classified into three types: type-A (FvRR1–7), type-B (FvRR8–14) and type-C (FvRR15–18) according to the domain architecture and the phylogeny. Phylogenetic analysis demonstrated that most cytokinin response regulators of F. vesca and Arabidopsis formed clear orthologous pairs. Expression patterns of the cytokinin FvRR genes in various tissues and organs at reproductive stages were detected in this study. Additionally, gene expression response patterns to ABA and abiotic stresses including high temperature and osmotic stress were investigated. The results showed that different types of cytokinin FvRRs have different expression patterns, suggesting the functional differentiation of cytokinin FvRRs during the evolution. This systematic study provides insights into possible functions of the cytokinin FvRR genes and a basis for further functional analysis.

GhATAF1, a NAC transcription factor, confers abiotic and biotic stress responses by regulating phytohormonal signaling networks

Dual function of GhATAF1 in the responses to salinity stress and Verticillium dahliae infection in cotton. NAC (NAM/ATAF1/2/CUC2) is a large plant-specific transcription factor family that plays important roles in the response to abiotic stresses. We previously isolated a cotton NAC transcription factor gene, GhATAF1, which was up-regulated by ABA, cold and salt stresses and classified into AFAT1/2, a sub-family of NAC. Here, we report that GhATAF1 was also highly induced by MeJA, SA and Verticillium dahliae inoculation, which implied that GhATAF1 was involved not only in the response to abiotic stress but also in the response to biotic stress. GhATAF1 was localized in the nucleus and possessed transactivation activity. Overexpression of GhATAF1 enhanced cotton plant tolerance to salt stress by enhancing the expression of various stress-related genes, including the ABA response gene GhABI4; the transporter gene GhHKT1, involved in Na(+)/K(+) homeostasis; and several stress-response genes (GhAVP1, GhRD22, GhDREB2A, GhLEA3, and GhLEA6). Additionally, overexpressing GhATAF1 increased cotton plant susceptibility to the fungal pathogens V. dahliae and Botrytis cinerea, coupled with the suppression of JA-mediated signaling and the activation of SA-mediated signaling. Our results suggested that GhATAF1, the cotton stress-responsive NAC transcription factor, plays important roles in the response to both abiotic stress and biotic stress by coordinating the phytohormone signaling networks.

Genome-wide identification, characterization and expression profiling of LIM family genes in Solanum lycopersicum L.

LIM domain proteins, some of which have been shown to be actin binding proteins, are involved in various developmental activities and cellular processes in plants. To date, the molecular defense-related functions of LIM family genes have not been investigated in any solanaceous vegetable crop species. In this study, we identified 15 LIM family genes in tomato (Solanum lycopersicum L.) through genome-wide analysis and performed expression profiling in different organs of tomato, including fruits at six different developmental stages. We also performed expression profiling of selected tomato LIM genes in plants under ABA, drought, cold, NaCl and heat stress treatment. The encoded proteins of the 15 tomato LIM genes were classified into two main groups, i.e., proteins similar to cysteine-rich proteins and plant-specific DAR proteins, based on differences in functional domains and variability in their C-terminal regions. The DAR proteins contain a so far poorly characterized zinc-finger-like motif that we propose to call DAR-ZF. Six of the 15 LIM genes were expressed only in flowers, indicating that they play flower-specific roles in plants. The other nine genes were expressed in all organs and at various stages of fruit development. SlβLIM1b was expressed relatively highly at the later stage of fruit development, but three other genes, SlWLIM2a, SlDAR2 and SlDAR4, were expressed at the early stage of fruit development. Seven genes were induced by ABA, five by cold, seven by drought, eight by NaCl and seven by heat treatment respectively, indicating their possible roles in abiotic stress tolerance. Our results will be useful for functional analysis of LIM genes during fruit development in tomato plants under different abiotic stresses.

ATP-Citrate Lyase Gene (SoACLA-1), a Novel ACLA Gene in Sugarcane, and Its Overexpression Enhance Drought Tolerance of Transgenic Tobacco

ATP-citrate lyase catalyzes cracking citrate to produce acetyl CoA in the cytoplasm and plays an important role in normal growth and development of plants. In this study, SoACLA-1 gene in sugarcane was cloned and characterized. The amino acid sequence of SoACLA-1 showed high homology with other ACLAs families, and they were clustered together in the phylogenetic tree. On transcript level, SoACLA-1 expressed strongly in root and stalk and responded to polyethylene glycol 6000, drought and ABA stresses. The results indicated that SoACLA-1 possibly involves in stress-responsive metabolic process. PCR analysis was performed to confirm the putative transgenic type in T1 tobacco plants. Overexpression of SoACLA-1 enhanced the tolerance of tobacco plants to drought. The sense transgenic tobacco plants were healthier, had longer roots and higher contents of relative water content and chlorophyll and activities of superoxide dismutase, peroxidase and catalase, but lower ion leakage and contents of malondialdehyde (MDA) and H2O2 than the wild-type and antisense transgenic plants under drought stress. In conclusion, SoACLA-1 plays an important role as a positive factor in drought stress response pathways and can be utilized for transformation to improve crop drought tolerance.

Wheat WRKY Type Transcription Factor Gene TaWRKY1 is Essential in Mediating Drought Tolerance Associated with an ABA-Dependent Pathway

WRKY-type transcription factors (TFs) are important regulators in plant growth, development and responses to diverse biotic and abiotic stresses. In this study, we characterized the function of TaWRKY1, a wheat (Triticum aestivum) WRKY family gene, in mediating plant tolerance to drought. TaWRKY1 bears a conserved WRKY motif and a C2H2 domain and targets onto the nucleus under both normal and simulated drought conditions. On exposure to simulated drought and ABA, the TaWRKY1 expression levels were significantly up-regulated. Ectopic overexpression of TaWRKY1 in tobacco conferred improved tolerance to drought; the transgenic plants exhibited more biomass, slower leaf water loss rate (WLR), more osmolyte accumulation, and higher antioxidant enzyme activities than wild type (WT) plants after drought treatments. In addition, the stomata closure rate was promoted in the transgenic plants upon exposure to drought and -exogenous ABA with respect to that in WT plants, suggesting that TaWRKY1 mediates the stomata movement and impacts the leaf water retention capacity. The transcripts of NtPYL8, an ABA receptor gene in tobacco, were shown to be induced in the TaWRKY1-overexpressing plants under drought and ABA stresses. Moreover, overexpression and knockdown of NtPYL8 modified the stomata movement characterization, leaf WLR, and phenotype of the seedlings upon exposure to the drought stress. These findings suggest that NtPYL8 acts as one of the critical players in transducing ABA signaling initiated by osmotic stress, contributing to the TaWRKY1-mediated drought tolerance via regulating stomata movement and plant water retention capacity. Our findings together reveal that TaWRKY1 plays an important role in mediating the plant tolerance to drought through modification of a set of osmotic stress-defensive processes connecting an ABA-dependent pathway. NtPYL8 and its homolog in wheat are crucial members in transducing the drought-initiated ABA signaling and are functional in modulating stomata movement.