Role Of WRKY Transcription Factors Research Articles

WRKY Transcription Factor Responses and Tolerance to Abiotic Stresses in Plants.

Plants are subjected to abiotic stresses throughout their developmental period. Abiotic stresses include drought, salt, heat, cold, heavy metals, nutritional elements, and oxidative stresses. Improving plant responses to various environmental stresses is critical for plant survival and perpetuation. WRKY transcription factors have special structures (WRKY structural domains), which enable the WRKY transcription factors to have different transcriptional regulatory functions. WRKY transcription factors can not only regulate abiotic stress responses and plant growth and development by regulating phytohormone signalling pathways but also promote or suppress the expression of downstream genes by binding to the W-box [TGACCA/TGACCT] in the promoters of their target genes. In addition, WRKY transcription factors not only interact with other families of transcription factors to regulate plant defence responses to abiotic stresses but also self-regulate by recognising and binding to W-boxes in their own target genes to regulate their defence responses to abiotic stresses. However, in recent years, research reviews on the regulatory roles of WRKY transcription factors in higher plants have been scarce and shallow. In this review, we focus on the structure and classification of WRKY transcription factors, as well as the identification of their downstream target genes and molecular mechanisms involved in the response to abiotic stresses, which can improve the tolerance ability of plants under abiotic stress, and we also look forward to their future research directions, with a view of providing theoretical support for the genetic improvement of crop abiotic stress tolerance.

Network analysis uncovers the master role of WRKY transcription factors in Arabidopsis thaliana response to N-acyl homoserine lactones

BackgroundPlants can perceive bacterial molecules such as the quorum sensing signals N-acyl homoserine lactones (AHL), thus modifying their fitness in response to environmental factors. Even though the benefits conferred by AHL depend on various hormone signaling pathways, the understanding of AHL signaling, especially the response to AHL presence, remains largely unknown.MethodsWeighted gene co-expression network analysis (WGCNA), multi-omics network analysis, and reverse transcription quantitative PCR (RT-qPCR) assays were used to identify key genes in AHL signaling.ResultsTo obtain comprehensive insights on AHL signaling, we integrated available transcriptome data from Arabidopsis thaliana exposed to different single or multiple AHL molecules and performed a weighted gene co-expression network analysis. We identified several key genes regulated in plants exposed to multiple AHL molecules. Multi-omics network analysis and RT-qPCR assay revealed a potential role of WRKY transcription factors.ConclusionsResults presented here offer good indications for exploring the mechanism of plants' response to bacterial signaling molecules, which could further support the application of AHL-producing bacteria in sustainable agriculture.

Signaling and Defence Mechanism of Jasmonic and Salicylic Acid Response in Pulse Crops: Role of WRKY Transcription Factors in Stress Response

Signaling and Defence Mechanism of Jasmonic and Salicylic Acid Response in Pulse Crops: Role of WRKY Transcription Factors in Stress Response

Multifaceted roles of WRKY transcription factors in abiotic stress and flavonoid biosynthesis.

Increasing biotic and abiotic stresses are seriously impeding the growth and yield of staple crops and threatening global food security. As one of the largest classes of regulators in vascular plants, WRKY transcription factors play critical roles governing flavonoid biosynthesis during stress responses. By binding major W-box cis-elements (TGACCA/T) in target promoters, WRKYs modulate diverse signaling pathways. In this review, we optimized existing WRKY phylogenetic trees by incorporating additional plant species with WRKY proteins implicated in stress tolerance and flavonoid regulation. Based on the improved frameworks and documented results, we aim to deduce unifying themes of distinct WRKY subfamilies governing specific stress responses and flavonoid metabolism. These analyses will generate experimentally testable hypotheses regarding the putative functions of uncharacterized WRKY homologs in tuning flavonoid accumulation to enhance stress resilience.

Genome-wide identification and expression profiling of the WRKY gene family reveals abiotic stress response mechanisms in Platycodon grandiflorus

The WRKY family of transcription factors (TFs) is an important gene family involved in abiotic stress responses. Although the roles of WRKY TFs in plant abiotic stress responses are well studied, little is known about the stress-induced changes in WRKY family in Platycodon grandiflorus. 42 PgWRKY genes in seven subgroups were identified in the P. grandiflorus genome. The content of eight platycodins in P. grandiflorus was investigated under cold, heat, and drought stresses. Platycodin D levels significantly increased under three abiotic stresses, while the content changes of other platycodins varied. Transcriptome analysis showed that different WRKY family members exhibited varied expression patterns under different abiotic stresses. PgWRKY20, PgWRKY26, and PgWRKY39 were identified as three key candidates for temperature and drought stress responses, and were cloned and analysed for sequence characteristics, gene structure, subcellular localisation, and expression patterns. The RT-qPCR results showed that PgWRKY26 expression significantly increased after heat stress for 48 h, cold stress for 6 h, and drought stress for 2 d (DS_2 d). The PgWRKY39 expression level significantly increased at DS_2 d. This study provides a theoretical basis for clarifying the molecular mechanism of the abiotic stress responses of the WRKY gene family in P. grandiflorus.

The role of WRKY transcription factors in exogenous potassium (K+) response to NaCl stress in Tamarix ramosissima.

Introduction: Soil salinization poses a significant challenge to plant growth and vitality. Plants like Tamarix ramosissima Ledeb (T. ramosissima), which are halophytes, are often integrated into planting schemes tailored for saline environments. Yet, the role of WRKY transcription factors in T. ramosissima, especially under sodium chloride (NaCl) stress mitigated by exogenous K+ application, is not well-understood. This research endeavors to bridge this knowledge gap. Methods: Using Pfam protein domain prediction and physicochemical property analysis, we delved into the WRKY genes in T. ramosissima roots that are implicated in counteracting NaCl stress when aided by exogenous K+ applications. By observing shifts in the expression levels of WRKY genes annotated to the KEGG pathway under NaCl stress at 0, 48, and 168h, we aimed to identify potential key WRKY genes. Results: We found that the expression of 56 WRKY genes in T. ramosissima roots responded to exogenous K+ application during NaCl stress at the indicated time points. Particularly, the expression levels of these genes were primarily upregulated within 168h. From these, 10 WRKY genes were found to be relevant in the KEGG pathways. Moreover, six genes, namely Unigene0024962, Unigene0024963, Unigene0010090, Unigene0007135, Unigene0070215, and Unigene0077293, were annotated to the Plant-pathogen interaction pathway or the MAPK signaling pathway in plants. These genes exhibited dynamic expression regulation at 48h with the application of exogenous K+ under NaCl stress. Discussion: Our research highlights that WRKY transcription factors can modulate the activation or inhibition of related genes during NaCl stress with the application of exogenous K+. This regulation enhances the plant's adaptability to saline environments and mitigates the damage induced by NaCl. These findings provide valuable gene resources for future salt-tolerant Tamarix breeding and expand our understanding of the molecular mechanisms of WRKY transcription factors in alleviating NaCl toxicity.

Genomic identification and expression profiling of WRKY genes in alfalfa (Medicago sativa) elucidate their responsiveness to seed vigor

BackgroundSeed aging is a critical factor contributing to vigor loss, leading to delayed forage seed germination and seedling growth. Numerous studies have revealed the regulatory role of WRKY transcription factors in seed development, germination, and seed vigor. However, a comprehensive genome-wide analysis of WRKY genes in Zhongmu No.1 alfalfa has not yet been conducted.ResultsIn this study, a total of 91 MsWRKY genes were identified from the genome of alfalfa. Phylogenetic analysis revealed that these MsWRKY genes could be categorized into seven distinct subgroups. Furthermore, 88 MsWRKY genes were unevenly mapped on eight chromosomes in alfalfa. Gene duplication analysis revealed segmental duplication as the principal driving force for the expansion of this gene family during the course of evolution. Expression analysis of the 91 MsWRKY genes across various tissues and during seed germination exhibited differential expression patterns. Subsequent RT-qPCR analysis highlighted significant induction of nine selected MsWRKY genes in response to seed aging treatment, suggesting their potential roles in regulating seed vigor.ConclusionThis study investigated WRKY genes in alfalfa and identified nine candidate WRKY transcription factors involved in the regulation of seed vigor. While this finding provides valuable insights into understanding the molecular mechanisms underlying vigor loss and developing new strategies to enhance alfalfa seed germinability, further research is required to comprehensively elucidate the precise pathways through which the MsWRKY genes modulate seed vigor.

The role of WRKY transcription factors, FaWRKY29 and FaWRKY64, for regulating Botrytis fruit rot resistance in strawberry (Fragaria × ananassa Duch.)

BackgroundThe cultivated strawberry (Fragaria × ananassa Duch.) is one of the most economically important horticultural crops worldwide. Botrytis fruit rot (BFR) caused by the necrotrophic fungal pathogen Botrytis cinerea is the most devasting disease of cultivated strawberries. Most commercially grown strawberry varieties are susceptible to BFR, and controlling BFR relies on repeated applications of various fungicides. Despite extensive efforts, breeding for BFR resistance has been unsuccessful, primarily due to lack of information regarding the mechanisms of disease resistance and genetic resources available in strawberry.ResultsUsing a reverse genetics approach, we identified candidate genes associated with BFR resistance and screened Arabidopsis mutants using strawberry isolates of B. cinerea. Among the five Arabidopsis T-DNA knockout lines tested, the mutant line with AtWRKY53 showed the greatest reduction in disease symptoms of BFR against the pathogen. Two genes, FaWRKY29 and FaWRKY64, were identified as orthologs in the latest octoploid strawberry genome, ‘Florida Brilliance’. We performed RNAi-mediated transient assay and found that the disease frequencies were significantly decreased in both FaWRKY29- and FaWRKY64-RNAi fruits of the strawberry cultivar, ‘Florida Brilliance’. Furthermore, our transcriptomic data analysis revealed significant regulation of genes associated with ABA and JA signaling, plant cell wall composition, and ROS in FaWRKY29 or FaWRKY64 knockdown strawberry fruits in response to the pathogen.ConclusionOur study uncovered the foundational role of WRKY transcription factor genes, FaWRKY29 and FaWRKY64, in conferring resistance against B. cinerea. The discovery of susceptibility genes involved in BFR presents significant potential for developing resistance breeding strategies in cultivated strawberries, potentially leveraging CRISPR-based gene editing techniques.

Bioinformatics Analysis of WRKY Family Genes in Flax (Linum usitatissimum).

WRKY gene family is one of the largest transcription factor families involved in various physiological processes of plants. Flax (Linum usitatissimum) is an important stem fiber crop, and it is also an economically important crop in natural fiber and textile industries around the world. In this study, 105 WRKY genes were obtained by screening the whole genome of flax. There were 26 in group I, 68 in group II, 8 in group III and 3 in group UN. The characteristics of the WRKY motif and gene structure in each group are similar. The promoter sequence of WRKY genes includes photoresponsive elements, core regulatory elements and 12 cis-acting elements under abiotic stress. Similar to A. thaliana and Compositae plants, WRKY genes are evenly distributed on each chromosome, with segmental and tandem repeated events, which play a major role in the evolution of WRKY genes. The flax WRKY gene family is mainly concentrated in group I and group II. This study is mainly based on genome-wide information to classify and analyze the flax WRKY gene family, laying a foundation for further understanding the role of WRKY transcription factors in species evolution and functional analysis.

Maize WRKY28 interacts with the DELLA protein D8 to affect skotomorphogenesis and participates in the regulation of shade avoidance and plant architecture.

Competition for light from neighboring vegetation can trigger the shade-avoidance response (SAR) in plants, which is detrimental to their yield. The molecular mechanisms regulating SAR are well established in Arabidopsis, and some regulators of skotomorphogenesis have been found to be involved in the regulation of the SAR and plant architecture. However, the role of WRKY transcription factors in this process has rarely been reported, especially in maize (Zea mays). Here, we report that maize Zmwrky28 mutants exhibit shorter mesocotyls in etiolated seedlings. Molecular and biochemical analyses demonstrate that ZmWRKY28 directly binds to the promoter regions of the Small Auxin Up RNA (SAUR) gene ZmSAUR54 and the Phytochrome-Interacting Factor (PIF) gene ZmPIF4.1 to activate their expression. In addition, the maize DELLA protein Dwarf Plant8 (D8) interacts with ZmWRKY28 in the nucleus to inhibit its transcriptional activation activity. We also show that ZmWRKY28 participates in the regulation of the SAR, plant height, and leaf rolling and erectness in maize. Taken together, our results reveal that ZmWRKY28 is involved in GA-mediated skotomorphogenic development and can be used as a potential target to regulate SAR for breeding of high-density-tolerant cultivars.

The Enhanced Affinity of WRKY Reinforces Drought Tolerance in Solanum lycopersicum L.: An Innovative Bioinformatics Study.

In the scenario of global climate change, understanding how plants respond to drought is critical for developing future crops that face restricted water resources. This present study focuses on the role of WRKY transcription factors on drought tolerance in tomato, Solanum lycopersicum L., which is a significant vegetable crop. WRKY transcription factors are a group of proteins that regulate a wild range of growth and developmental processes in plants such as seed germination and dormancy and the stress response. These transcription factors are defined by the presence of a DNA-binding domain, namely, the WRKY domain. It is well-known that WRKY transcription factors can interact with a variety of proteins and therefore control downstream activities. It aims to simulate the effect of curcumin, a bioactive compound with regulatory capacity, on the protein-protein interaction events by WRKY transcription factors with an emphasis on drought stress. It was found that curcumin binds to WRKY with an energy of -11.43 kcal/mol with inhibitory concentration (Ki) 0.12 mM and has the potential to improve fruit quality and reinforce drought tolerance of S. lycopersicum, according to the results based on bioinformatics tools. The root means square deviation (RMSD) of the C-α, the backbone of 2AYD with ligand coupled complex, displayed a very stable structure with just a little variation of 1.89 Å. MD simulation trajectory of Cα atoms of 2AYD bound to Curcumin revealed more un-ordered orientation in PC1 and PC10 modes and more toward negative correlation from the initial 400 frames during PCA. Establishing the binding energies of the ligand-target interaction is essential in order to characterize the compound's binding affinity to the drought transcription factor. We think we have identified a phyto-agent called curcumin that has the potential to enhance the drought tolerance. Compared to the part of the mismatch repair-base technique that can be used to fix drought related genes, curcumin performed better in a drop-in crop yield over time, and it was suggested that curcumin is a potential candidate factor for improving drought tolerance in tomatoes, and it needs future validation by experiments in laboratory and field.

Genome-Wide Identification and Characterization of the Oat (Avena sativa L.) WRKY Transcription Factor Family.

The WRKY family is widely involved in the regulation of plant growth and stress response and is one of the largest gene families related to plant environmental adaptation. However, no systematic studies on the WRKY family in oat (Avena sativa L.) have been conducted to date. The recently published complete genome sequence of oat enables the systematic analysis of the AsWRKYs. Based on a genome-wide study of oat, we identified 162 AsWRKYs that were unevenly distributed across 21 chromosomes; a phylogenetic tree of WRKY domains divided these genes into three groups (I, II, and III). We also analyzed the gene duplication events and identified a total of 111 gene pairs that showed strong purifying selection during the evolutionary process. Surprisingly, almost all genes evolved after the completion of subgenomic differentiation of hexaploid oat. Further studies on the functional analysis indicated that AsWRKYs were widely involved in various biological processes. Notably, expression patterns of 16 AsWRKY genes revealed that the response of AsWRKYs were affected by stress level and time. In conclusion, this study provides a reference for further analysis of the role of WRKY transcription factors in species evolution and functional differentiation.

Role of WRKY Transcription Factors in Regulation of Abiotic Stress Responses in Cotton.

Environmental factors are the major constraints in sustainable agriculture. WRKY proteins are a large family of transcription factors (TFs) that regulate various developmental processes and stress responses in plants, including cotton. On the basis of Gossypium raimondii genome sequencing, WRKY TFs have been identified in cotton and characterized for their functions in abiotic stress responses. WRKY members of cotton play a significant role in the regulation of abiotic stresses, i.e., drought, salt, and extreme temperatures. These TFs either activate or repress various signaling pathways such as abscisic acid, jasmonic acid, salicylic acid, mitogen-activated protein kinases (MAPK), and the scavenging of reactive oxygen species. WRKY-associated genes in cotton have been genetically engineered in Arabidopsis, Nicotiana, and Gossypium successfully, which subsequently enhanced tolerance in corresponding plants against abiotic stresses. Although a few review reports are available for WRKY TFs, there is no critical report available on the WRKY TFs of cotton. Hereby, the role of cotton WRKY TFs in environmental stress responses is studied to enhance the understanding of abiotic stress response and further improve in cotton plants.

Genomic insights of the WRKY genes in kenaf (Hibiscus cannabinus L.) reveal that HcWRKY44 improves the plant's tolerance to the salinity stress.

The WRKY transcription factors (TFs) are among the most diverse TF families of plants. They are implicated in various processes related to plant growth and stress response. Kenaf (Hibiscus cannabinus L.), an important fiber crop, has many applications, including the phytoremediation of saline-alkaline soil. However, the roles of WRKY TFs in kenaf are rarely studied. In the present study, 46 kenaf WRKY genes were genome-widely identified and characterized by gene structure, phylogeny and expression pattern analysis. Furthermore, the HcWRKY44 gene was functionally characterized in Arabidopsis under salinity and drought stresses. HcWRKY44 is a nuclear-localized protein that is positively induced by salinity and drought, with roots showing maximum accumulation of its transcripts. Under NaCl and abscisic acid (ABA) stress conditions, plants overexpressing HcWRKY44 had higher germination rates, better root growth and increased survival than control plants; however, it did not improve the ability to withstand drought stress. Moreover, ABA signaling genes (ABI1, ABI2, and ABI5), ABA-responsive genes (ABF4, RD29B, COR15A, COR47, and RD22), stress-related genes (STZ, P5CS, and KIN1), and ionic homeostasis-related genes (SOS1, AHA1, AHA2, and HKT1) were positively induced in HcWRKY44 transgenic plants under NaCl treatment. These results suggest that HcWRKY44 improved plant's tolerance to salt stress but not osmotic stress through an ABA-mediated pathway. In summary, this study provides provided comprehensive information about HcWRKY genes and revealed that HcWRKY44 is involved in salinity tolerance and ABA signaling.

WRKY transcription factors: a promising way to deal with arsenic stress in rice.

Arsenic (As) is a global carcinogenic contaminant, and is one of the significant environmental constraints that limits the development and yield of crop plants. It is always tagged along with rice as rice takes up As and tends to accumulate it in grains. This amassment makes a way for As to get into the food chain that leads to unforeseen human health risks. Being viewed as parallel with toxicity, As in rice is an important global risk that calls for an urgent solution. WRKY Transcription Factors (TFs) seems to be promising in this area. The classical and substantial progress in the molecular mechanism of WRKY TFs, strengthened the understanding of innovative solutions for dealing with As in rice. Here, we review the potential of WRKY TFs under As stressed rice as a genetic solution and also provide insights into As and rice. Further, we develop an understanding of WRKY TF gene family and its regulation in rice. To date, studies on the role of WRKY TFs under As stressed rice are lacking. This area needs to be explored more so that this gene family can be utilized as an effective genetic tool that can break the As cycle to develop low or As free rice cultivar.

The roles of WRKY transcription factors in Malus spp. and Pyrus spp.

The WRKY transcription factor gene family is known to be involved in plant defense against pathogens and in tolerance to different environmental stresses at different stages of development. The response mechanisms through which these genes act can be influenced by different phytohormones as well as by many trans- and cis-acting elements, making this network an important topic for analysis, but still something complex to fully understand. According to available reports, these genes can also perform important roles in pome species (Malus spp. and Pyrus spp.) metabolism, especially in adaptation of these plants to stressful conditions. Here, we present a quick review of what is known about WRKY genes in Malus and Pyrus genomes offering a simple way to understand what is already known about this topic. We also add information connecting the evolution of these transcription factors with others that can also be found in pomes.

Identification of drought responsive Elaeis guineensis WRKY transcription factors with sensitivity to other abiotic stresses and hormone treatments

BackgroundThe ability of plants to withstand and thrive in an adverse environment is crucial to ensure their survivability and yield performance. The WRKY transcription factors (TFs) have crucial roles in plant growth, development and stress response, particularly drought stress. In oil palm, drought is recognized as one of the major yield limiting factors. However, the roles of WRKY TFs in the drought response of oil palm is unclear.ResultsHerein, we studied the transcriptome of drought treated oil palm leaf and identified 40 differentially expressed genes (DEGs) of WRKY TFs, of which 32 DEGs were upregulated and 8 DEGs were downregulated in response to drought stress in oil palm. They were categorized into Groups I to IV based on the numbers of WRKY domain and the structural difference in the zinc finger domain. Multiple stress- and hormone-responsive cis-regulatory elements were detected in the drought responsive oil palm EgWRKY (Dro-EgWRKY) genes. Fourteen of the 15 selected oil palm WRKY (EgWRKY) genes demonstrated a tissue-specific expression profile except for EgWRKY28 (Group I), which was expressed in all tissues tested. The expression levels of 15 candidate EgWRKYs were upregulated upon salinity and heat treatments, while several genes were also inducible by abscisic acid, methyl jasmonate, salicylic acid and hydrogen peroxide treatments. Members of the Group III WRKY TFs including EgWRKY07, 26, 40, 52, 59, 73 and 81 displayed multiple roles in drought- and salinity-response under the modulation of phytohormones.ConclusionsEgWRKY TFs of oil palm are involved in phytohormones and abiotic stress responses including drought, salinity and heat. EgWRKY07, 26, 59 and 81 from Group III maybe important regulators in modulating responses of different abiotic stresses. Further functional analysis is required to understand the underlying mechanism of WRKY TFs in the regulatory network of drought stress.

StWRKY13 promotes anthocyanin biosynthesis in potato (Solanum tuberosum) tubers.

Although the role of WRKY transcription factors (TFs) in colour formation has been reported in several species, their function in potato (Solanum tuberosum L.) anthocyanin biosynthesis remains unclear. In this study, the potato WRKY gene StWRKY13 was isolated and characterised. Expression analysis revealed a significantly higher StWRKY13 expression in chromatic tubers than in yellow ones. Transient activation assays showed that StWRKY13 could enhance the role of StAN2 in promoting anthocyanin biosynthesis in tobacco (Nicotiana tabacum L.). Over-expressing the StWRKY13 gene promoted anthocyanin biosynthesis in potato tubers. Further investigations indicated that StWRKY13 could interact with the StCHS, StF3H, StDFR, and StANS gene promoters and significantly enhance their activities. Our findings showed that StWRKY13 could promote anthocyanin biosynthesis by activating StCHS, StF3H, StDFR, and StANS transcription in potato tubers, thereby supporting the theoretical basis for anthocyanins formation in coloured potato tubers.

Role of WRKY transcription factors in plant defense against lepidopteran insect herbivores: an overview

Role of WRKY transcription factors in plant defense against lepidopteran insect herbivores: an overview

TaWRKY70 positively regulates TaCAT5 enhanced Cd tolerance in transgenic Arabidopsis

The WRKY transcription factors (TFs) are involved in plant responses to multiple biotic and abiotic stressors; however, the role of WRKY TFs in the regulation of Cd stress in wheat remains unknown. In this study, we investigated the mechanism of the wheat TaWRKY70 TF in Cd stress. TaWRKY70 expression in Arabidopsis was used for the functional analysis. TaWRKY70 regulated Cd tolerance with Cd accumulating in roots but not in the leaf tissues of transgenic Arabidopsis. The net Cd2+ influx into Arabidopsis roots decreased when TaWRKY70 was expressed. The quantitative real-time-polymerase chain reaction (qRT-PCR) results showed that the expression levels of heavy metal ATPase (AtHMA3), natural resistance-associated macrophage protein (AtNRAMP5), yellow stripe1-like (AtYSL3), and iron transport protein (AtIRT1) decreased under Cd-stress condition. Electrolyte leakage, as well as malondialdehyde and hydrogen peroxide contents, were lower in transgenic Arabidopsis than those in the wild-type (WT), whereas antioxidant enzyme activities were higher. Electrophoretic mobility shift assay (EMSA), yeast one-hybrid (Y1H) assay, and transient transactivation assay confrmed that TaWRKY70 could directly bind to the TaCAT5 promoter. Our findings provide a novel understanding of the WRKY TFs involved in the response to heavy metal stress.