WRKY Transcription Factors Research Articles

CaWRKY20 Negatively Regulates Plant Resistance to Colletotrichum scovillei in Pepper.

Chili anthracnose, a fungal disease caused by Colletotrichum scovillei, is among the most devastating diseases affecting pepper (Capsicum annuum L.). Although WRKY transcription factors play important roles in plant immunity, it is unknown how WRKY gene family members contribute to pepper plant resistance to C. scovillei. Here, CaWRKY20 was found to negatively regulate pepper resistance to C. scovillei, which was demonstrated by virus-induced gene silencing and transient overexpression in pepper. Moreover, overexpression of CaWRKY20 enhanced susceptibility to C. scovillei in tomato. Additionally, our findings demonstrated that CaWRKY20 can indirectly regulate the expression of salicylic acid (SA)-related defense genes (CaPR1, CaPR10 and CaSAR8.2) as well as reactive oxygen species (ROS)-scavenging enzyme genes (CaCAT, CaPOD and CaSOD) in response to C. scovillei. In addition, CaWRKY20 was found to interact with CaMIEL1 in the nucleus to regulate the defense response to C. scovillei in pepper. Furthermore, CaWRKY20 directly bound to the W-box in the promoter of SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (CaSARD1) and suppressed its expression, resulting in reduced resistance to C. scovillei. These results will clarify the mechanism by which WRKY transcription factors are involved in pepper disease resistance and can thus facilitate molecular breeding for anthracnose-resistant varieties.

Transcription Factor CmWRKY13 Regulates Cucurbitacin B Biosynthesis Leading to Bitterness in Oriental Melon Fruit (Cucumis melo var. Makuwa Makino).

Bitterness, caused by cucurbitacin B (CuB), is one of the important traits that affects melon fruit quality and consumer acceptance. Therefore, the detailed mechanism behind the regulation of CuB biosynthesis on melon fruit needs to be further explored. This study investigated CuB content and transcriptomes of "YMR" melon fruit treated by 5 and 20 mg L-1 CPPU. The content of CuB reaches its peak in 5 days and then decreases. WGCNA identified the WRKY transcription factor (TF), CmWRKY13, coexpressed with CuB biosynthetic genes (Cm180, Cm170, Cm160, and CmACT). Yeast one-hybrid, dual-luciferase, and transient gene expression assays were conducted and suggested that the nucleus-localized CmWRKY13 transactivated the promoters of CuB biosynthetic genes and participated in the regulation of CuB biosynthesis. Furthermore, CmWRKY13 could interact with CmBt, the fruit bitterness-specific TF, which synergistically activated CuB biosynthetic gene expression. These findings provide a novel mechanistic insight for CuB biosynthesis and regulation in melon cultivation.

GmWRKY33A positively regulates disease resistance in soybean (Glycine max)

The WRKY transcription factor gene family is a plant-specific transcription factor that plays important roles defense responses. Studies in model plant Arabidopsis demonstrated that WRKYs function downstream of mitogen activated-protein kinase (MAPK) signaling cascade and participate in defense responses through activating the expression of defense-related genes. However, the roles of WRKYs in defense responses have not been previously investigated in paleopolyploidy soybean. Bioinfomatic analysis revealed that there are three pair of GmWRKY33 genes in the soybean genome. The identity of first two pair of GmWRKY33 genes is greater than 84% (named as GmWRKY33A). The identity of genes within the same pair is greater than 95%. A 300 bp fragment highly homologous to these four GmWRKY33A was chosen to clone into bean pod mosaic virus (BPMV)-based silencing vector (BPMV-VIGS) to achieve the goal of silencing four GmWRKY33A genes simultaneously. In this study, we simultaneously silenced four homologous genes of GmWRKY33A using a bean pod mottle virus (BPMV) vector carrying a single fragment of GmWRKY33A. Comparing the silenced plants with the vector control plants, no evident morphological phenotypes were observed. However, the GmWRKY33A-silenced plants exhibited significantly reduced resistance to Pseudomonas syringae pv. glycinea (Psg), Xanthomonas axonopodis pv. glycine (Xag), as well as to soybean mosaic virus (SMV). Furthermore, we demonstrated that silencing these GmWRKY33A genes significantly inhibited the activation of GmMPK3/GmMPK6 induced by Psg infection. Collectively, our results suggest that GmWRKY33As are involved in soybean immunity through regulating the transcription of GmMPK3/6 genes or activating the kinase activities of GmMPK3/6. Taken together, our results demonstrated that GmWRKY33As are positive regulators of soybean immune responses.

WRKY Transcription Factors (TFs) as Key Regulators of Plant Resilience to Environmental Stresses: Current Perspective

Plants encounter various stresses in their natural environments and can effectively respond to only one stress at a time. Through a complex gene network, transcription factors (TFs) such as WRKY TFs regulate a diverse array of stress responses. The clarification of the structural characteristics of WRKY proteins, along with recent advancements in molecular dynamics simulations, has shed light on the formation, stability, and interactions of DNA–protein complexes. This has provided a novel viewpoint regarding the control of WRKY TFs. The investigation of superfamilies, encompassing their historical development, diversity, and evolutionary patterns, has become feasible due to the transcriptome approach’s capacity to provide extensive and comprehensive transcripts. The significance of WRKY TFs lies in their pivotal role within several signaling cascades and regulatory networks that influence plant defense responses. The present review summarizes the functional aspects of the high-volume sequence data of WRKY TFs from different species studied to date. Moreover, a comparative analysis approach was utilized to determine the functions of the identified WRKY TFs in response to both abiotic and biotic stresses, as revealed through numerous studies on different plant species. The results of this review will be pivotal in understanding evolutionary events and the significance of WRKY TFs in the context of climate change, incorporating new scientific evidence to propose an innovative viewpoint.

A transcription factor, PbWRKY24, contributes to russet skin formation in pear fruits by modulating lignin accumulation

Abstract Skin color is one of the major traits of fruit appearance quality in pear (Pyrus), which affects the fruit commodity value. Russet skin protects pear fruits from environmental stresses and its formation process is closely linked to lignin accumulation. However, the molecular regulatory networks underlying russet skin formation in pear fruits involve complex secondary metabolic pathways and remain elusive. Here, we explored the regulatory mechanisms underlying lignin accumulation in pear skin based on transcriptome sequencing, co-expression network analysis, and gene expression profiling. We identified a WRKY transcription factor gene, PbWRKY24, that regulates russet skin formation in pear fruits. The relative expression of PbWRKY24 in russet pear skin was significantly correlated with lignin content. We then verified the function of PbWRKY24 in lignin accumulation via genetic transformation. DNA affinity purification sequencing revealed that PbWRKY24 directly binds to the promoter of a lignin biosynthesis gene, PbPRX4. This binding was confirmed by yeast one-hybrid, dual-luciferase, and electrophoretic mobility shift assays. Overexpression of PbPRX4 in pear skin stimulated lignin accumulation and consequently promoted russet skin formation. This study provides a glimpse into the intricate lignin biosynthesis mechanisms during russet skin formation in pear fruits, which is of practical significance to pear breeding for fruit quality.

Transcriptome sequencing analysis of overexpressed SikCDPK1 in tobacco reveals mechanisms of cold stress response

BackgroundCold is a significant limiting factor in productivity, particularly in northwestern and eastern China. Calcium-Dependent Protein Kinases (CDPKs), a primary calcium signaling sensor in plants, play an important role in their response to cold. Snow lotus (Sasussured involucrata Kar L) is a plant that thrives in harsh climates and grows in northwest China. However, there were no reports on the transcriptome of OE-SikCDPK1 transgenic tobacco in response to cold.ResultsWhen exposed to cold stress, OE-SikCDPK1 plants displayed a cold-tolerant phenotype compared to non-transgenic tobacco. Under cold conditions, relative water content reduced, relative conductivity increased, malondialdehyde levels rose, and cold-responsive gene expression increased. The OE-SikCDPK1 gene and non-transgenic tobacco were employed for research purposes. The transcriptome of leaves was sequenced using the HISAT2 sequencing platform, and the data were used to examine gene function annotation and differentially expressed genes (DEGs). 53,022 DEGs in tobacco leaves under cold treatment were obtained. The GO enrichment results revealed that it was enriched for biological-process, defense response and other processes under cold stress. The KEGG pathway enrichment analysis revealed that the metabolic pathways of significant enrichment of DEGs under cold stress mainly involved MAPK signaling pathway transduction. The transcription factor identification results showed that the transcription factors with the largest number of differential expressions under cold treatment were mainly from WRKY, AP2, MYB, bHLH, NAC and other transcription factor families.ConclusionThe cold tolerance mechanism of snow lotus SikCDPK1 was comprehensively analyzed at the transcriptional level for the first time using RNA-seq technology. This study demonstrates that SikCDPK1 can respond to cold by participating in the MAPK signaling pathway and regulating the expression levels of transcription factors, including WRKY, AP2, MYB, bHLH, and NAC. These results offer valuable insights for further exploration of the cold tolerance mechanism associated with SikCDPK1.

Transcriptome analysis reveals role of transcription factor WRKY70 in early N-hydroxy-pipecolic acid signaling.

N-hydroxy-pipecolic acid (NHP) is a mobile metabolite essential for inducing and amplifying systemic acquired resistance (SAR) following pathogen attack. Early phases of NHP signaling leading to immunity have remained elusive. Here, we report the early transcriptional changes mediated by NHP and the role salicylic acid (SA) plays during this response in Arabidopsis (Arabidopsis thaliana). We show that distinct waves of expression within minutes to hours of NHP treatment include increased expression of WRKY transcription factor genes as the primary transcriptional response, followed by the induction of WRKY-regulated defense genes as the secondary response. Most genes induced by NHP within minutes were SA-dependent, whereas those induced within hours were SA-independent. These data suggest that NHP induces the primary transcriptional response under basal levels of SA and that new SA biosynthesis via ISOCHORISMATE SYNTHASE 1/SA-INDUCTION DEFICIT 2 (ICS1/SID2) is dispensable for inducing the secondary transcriptional response. We demonstrate that WRKY70 is required for the induced expression of a set of genes defining some of the secondary transcriptional response, SAR protection, and NHP-dependent enhancement of ROS production in response to flagellin treatment. Our study highlights the key genes and pathways defining early NHP responses and the role of WRKY70 in regulating NHP-dependent transcription.

WRKY Transcription Factors in Response to Metal Stress in Plants: A Review.

Heavy metals in soil can inflict direct damage on plants growing within it, adversely affecting their growth height, root development, leaf area, and other physiological traits. To counteract the toxic impacts of heavy metals on plant growth and development, plants mitigate heavy metal stress through mechanisms such as metal chelation, vacuolar compartmentalization, regulation of transporters, and enhancement of antioxidant functions. WRKY transcription factors (TFs) play a crucial role in plant growth and development as well as in responses to both biotic and abiotic stresses; notably, heavy metal stress is classified as an abiotic stressor. An increasing number of studies have highlighted the significant role of WRKY proteins in regulating heavy metal stress across various levels. Upon the entry of heavy metal ions into plant root cells, the production of reactive oxygen species (ROS) is triggered, leading to the phosphorylation and activation of WRKY TFs through MAPK cascade signaling. Activated WRKY TFs then modulate various physiological processes by upregulating or downregulating the expression of downstream genes to confer heavy metal tolerance to plants. This review provides an overview of the research advancements regarding WRKY TFs in regulating heavy metal ion stress-including cadmium (Cd), arsenic (As), copper (Cu)-and aluminum (Al) toxicity.

Members of WRKY Group III Transcription Factors Are Important in Mite Infestation in Strawberry (Fragaria × ananassa Duch.)

Strawberry is frequently attacked by mites, which directly affects the yield and quality of this fruit species. The WRKY Group III transcription factors (TFs) play an important role in plant tolerance to biotic sources of stress, such as pathogens and insect pests. In this study, six Group III WRKY TFs (FaWRKY25, FaWRKY31, FaWRKY32, FaWRKY43, FaWRKY44, and FaWRKY45) were identified in strawberry. A phylogenetic analysis showed that the six WRKY III TFs were divided into two clades and all had a conserved WRKYGQK domain and the C-X7-C-X23-H-T-C zinc finger motif. An interaction network analysis revealed that FaWRKY44 was co-expressing with FaWRKY25 and FaWRKY45. The expression patterns showed that the WRKY Group III genes responded to plant hormones and mite infestation in strawberry. To further verify the role of FaWRKY25 in plant resistance to mites, we cloned the FaWRKY25 gene and overexpressed it in transgenic plants. An in vivo subcellular localization analysis indicated that the FaWRKY25 protein was localized in the nucleus. Fewer mites were also detected on the wild-type plants than on FaWRKY25-overexpressing transgenic plants, suggesting that FaWRKY25 negatively regulates the resistance of strawberry to mites. The present study advances our understanding on a potential target that mites use to manipulate host plant defenses.

Genome-wide investigation of WRKY gene family in Lavandula angustifolia and potential role of LaWRKY57 and LaWRKY75 in the regulation of terpenoid biosynthesis.

The WRKY transcription factors are integral to plant biology, serving essential functions in growth, development, stress responses, and the control of secondary metabolism. Through the use of bioinformatics techniques, this research has effectively characterized 207 members of the WRKY family (LaWRKY) present in the entire genome of Lavandula angustifolia. Phylogenetic analysis classified LaWRKYs into three distinct categories based on conserved domains. Collinearity analysis revealed tandem repeats, segmental duplications, and whole genome duplications in LaWRKYs, especially for segmental duplication playing a significant role in gene family expansion. LaWRKYs displayed distinct tissue-specific expression profiles across six different tissues of L. angustifolia. Particularly noteworthy were 12 genes exhibiting high expression in flower buds and calyx, the primary sites of volatile terpenoid production, indicating their potential role in terpenoid biosynthesis in L. angustifolia. RT-qPCR analysis revealed a notable increase in the expression levels of most examined LaWRKY genes in flower buds in response to both intense light and low-temperature conditions, whereas the majority of these genes in leaves were primarily induced by drought stress. However, all genes exhibited downregulation following GA treatment in both flower buds and leaves. Overexpression of LaWRKY57 (La13G01665) and LaWRKY75 (La16G00030) in tobacco led to a reduction in the density of glandular trichomes on leaf surfaces, resulting in changes to the volatile terpenoid composition in the leaves. Specifically, the content of Neophytadiene was significantly elevated compared to wild-type tobacco, while compounds such as eucalyptol, cis-3-Hexenyl iso-butyrate, and D-Limonene were produced, which were absent in the wild type. These findings provide a valuable reference for future investigations into the biological functions of the WRKY gene family in L. angustifolia.

Genome-wide characterization and expression analysis of WRKY transcription factors reveals biotic stress response potential mechanisms in Panax notoginseng

WRKY transcription factors (TFs), among the largest families of transcriptional regulators, are essential players in defense responses in plants. Panax notoginseng, a traditional and precious herbal medicine in China, is widely cultivated due to its excellent medicinal and edible value. However, P. notoginseng is frequently affected by various diseases (like Black blot disease, Root rot disease and Viral diseases). Therefore, the present study aimed to identify and characterize PnWRKYs in the P. notoginseng genome, reveal their structural attributes, regulatory elements, and potential functions in defense responses. 68 PnWRKY TFs that have conserved domains and different physicochemical characteristics were identified in the genome. They can be divided into four groups according to phylogenetic relationships and conserved domain structures. Furthermore, Group II WRKY TFs can be classified into five subgroups (IIa, IIb, IIc, IId, and IIe) according to their zinc finger-like motif. The PnWRKY family expands mainly via segmental duplication. Additionally, the promoter regions of PnWRKYs contain many hormone-responsive and stress-responsive elements. Expression patterns under different hormones (salicylic acid, methyl jasmonate, and melatonin) and disease (root rot disease, black blot disease, and virus disease) treatment analysis highlighted their wide involvement in plant hormone-induced disease defense responses. These findings affirmed the potential functions of PnWRKY TFs in disease-mediated defense responses and provided valuable insights for future agricultural applications.

Maize stigmas react differently to self- and cross-pollination and fungal invasion.

During sexual reproduction in flowering plants, tip-growing pollen tubes travel from the stigma inside the maternal tissues of the pistil towards ovules. In maize (Zea mays L.), the stigma is highly elongated, forming thread-like strands known as silks. Only compatible pollen tubes successfully penetrate and grow through the transmitting tract of the silk to reach the ovules. Like pollen, fungal spores germinate at the surface of silks and generate tube-like structures (hyphae) penetrating silk tissue. To elucidate commonalities and differences between silk responses to these distinctive invading cells, we compared growth behavior of the various invaders as well as the silk transcriptome after self-pollination, cross-pollination and infection using two different fungi. We report that self-pollination triggers mainly senescence genes, whereas incompatible pollen from Tripsacum dactyloides leads to downregulation of rehydration, microtubule, and cell wall-related genes, explaining the slower pollen tube growth and arrest. Invasion by the ascomycete Fusarium graminearum triggers numerous defense responses including the activation of monolignol biosynthesis and NAC as well as WRKY transcription factor genes, whereas responses to the basidiomycete Ustilago maydis are generally much weaker. We present evidence that incompatible pollination and fungal infection trigger transcriptional reprograming of maize silks cell wall. Pathogen invasion also activates the phytoalexin biosynthesis pathway.

Two leucine-rich repeat receptor-like kinases initiate herbivory defense responses in tea plants

Abstract Leucine-rich repeat receptor-like kinases (LRR-RLKs) have emerged as key regulators of herbivory perception and subsequent defense initiation. While their functions in grass plants have been gradually elucidated, the roles of herbivory-related LRR-RLKs in woody plants remain largely unknown. In this study, we mined the genomic and transcriptomic data of tea plants (Camellia sinensis) and identified a total of 307 CsLRR-RLK members. Phylogenetic analysis grouped these CsLRR-RLKs into 14 subgroups along with their Arabidopsis homologs. Gene structure and conserved domain analyses revealed notable similarities among subgroup members. Among the identified CsLRR-RLKs, we focused on two plasma membrane-localized LRR-RLKs, CsLRR-RLK44 and CsLRR-RLK239, which do not form homodimers or heterodimers with each other. Both respond strongly to herbivory, and their expression patterns significantly correlate with herbivore resistance phenotypes across different tea accessions. CsLRR-RLK44 and CsLRR-RLK239 act upstream of mitogen-activated protein kinase (MPK) cascades and modulate the expression of defense-related MPKs and WRKY transcription factors. Additionally, silencing CsLRR-RLK44 or CsLRR-RLK239 reduced the levels of herbivory-induced jasmonates, thereby weakening the plant resistance to tea geometrid larvae (Ectropis obliqua). Our work is the first to demonstrate that in woody plants, LRR-RLKs are essential for enhancing herbivore resistance through the activation of the canonical signaling, including MPKs, WRKYs and jasmonates. Furthermore, our study extends mechanistic insights into how LRR-RLKs initiate plant defenses from grasses to economically important tree species.

An activator-represssor complex of VvWRKYs regulate proanthocyanidins biosynthesis through co-targeting VvLAR in grape

Proanthocyanidins (PAs) are vital polyphenolic compounds in plants with various biological functions. Although WRKY transcription factors are known to play important roles, their specific involvement in regulating PAs metabolism in grapes remains underexplored. In this study, we identified six candidate WRKY genes potentially involved in PAs synthesis by transiently overexpressing them in Nicotiana tabacum leaves. Among these, VvWRKY57 was found to enhance PAs synthesis. Further functional analysis, achieved by overexpressing of VvWRKY57 in grape calli, confirmed its positive role in PAs biosynthesis. Using yeast one-hybrid (Y1H), dual-luciferase reporter (DLR) assays, and electrophoretic mobility shift assay (EMSA), we demonstrated that VvWRKY57 binds to the promoter of leucocyanidin reductase (VvLAR2) and stimulates its activity. Additionally, yeast two-hybrid (Y2H), bimolecular fluorescence complementary (BiFC), and pull-down assays revealed that VvWRKY57 forms heterodimers with VvWRKY20, while VvWTKY20 also forms homodimers. Interestingly, overexpression of VvWRKY20 was found to inhibit PAs synthesis. Y1H, DLR, and EMSA further showed that VvWRKY20 binds to the promoters of VvLAR1 and VvLAR2, repressing their transcription activity. When VvWRKY57 and VvWRKY20 were co-expressed, VvLAR2 promoter activity and PAs synthesis were suppressed. Moreover, we discovered that VvPUB26, an E3 ubiquitin ligase physically interacts with both VvWRKY57 and VvWRKY20. VvPUB26 mediated the degradation of VvWRKY20 but did not influence the degradation of VvWRKY57. In conclusion, this study highlights the regulatory interplay between WRKY transcription factors in PAs biosynthesis, offering insights into their distinct roles in modulating this important metabolic pathway in grapes.

A note on the nomenclatural representation of plant transcription factors, and deviations thereof

Abstract Plant transcription factors (TFs) are integral proteins associated with gene transcription. That ability arises after TFs bind to specific DNA sequences, such as promoters, responding positively or negatively to a multitude of endogenous and exogenous factors or stressors. For this reason, in plants, the vast majority of TFs are associated with growth, development, and responses to biotic and abiotic stresses. As is commonly known, the genes coding for TFs are written in uppercase italics, whereas the resulting proteins are written in lowercase, such as OsWRKY28 and OsWRKY28, respectively for a member of the WRKY TF family in rice (Oryza sativa L.). However, despite the existence of some conventions for the nomenclature of TFs, some deviation from these norms has been observed in the literature. Several cases are highlighted, primarily related to NAC TFs. These cases emphasize the need for stricter quality control of literature pertaining to the nomenclature of plant TFs.

Genome-Wide Identification and Analysis of the WRKY Transcription Factor Family Associated with Leaf Senescence in Alfalfa

Leaves are the most significant parts of forage crops such as alfalfa. Senescence is the terminal stage of leaf development and is controlled by an integrated myriad of endogenous signals and environmental stimuli. WRKY transcription factors (TFs) play essential roles in regulating leaf senescence; however, only a few studies on the analysis and identification of the WRKY TF family in Medicago Sativa have been reported. In this study, we identified 198 WRKY family members from the alfalfa (M. sativa L.) cultivar ’XinjiangDaye’ using phylogenetic analysis and categorized them into three subfamilies, Groups I, II, and III, based on their structural characteristics. Group II members were further divided into five subclasses. In addition, several hormone- and stress-related cis-acting elements were identified in the promoter regions of MsWRKYs. Furthermore, 14 aging-related MsWRKYs genes from a previous transcriptome in our laboratory were selected for RT-qPCR validation of their expression patterns, and subsequently cloned for overexpression examination. Finally, MsWRKY5, MsWRKY66, MsWRKY92, and MsWRKY141 were confirmed to cause leaf yellowing in Nicotiana benthaminana using a transient expression system. Our findings lay a groundwork for further studies on the mechanism of M. sativa leaf aging and for the creation of new germplasm resources.

Transcription factor gene TaWRKY76 confers plants improved drought and salt tolerance through modulating stress defensive-associated processes in Triticum aestivum L.

WRKY transcription factor (TF) family acts as essential regulators in plant growth and abiotic stress responses. This study reported the function of TaWRKY76, a member of WRKY TF family in Triticum aestivum L., in regulating plant osmotic stress tolerance. TaWRKY76 transcripts were significantly upregulated upon drought and salt signaling, with dose extent- and stress temporal-dependent manners. Plant GUS activity assays suggested that stress responsive cis-acting elements, such as DRE and ABRE, exert essential roles in defining gene transcription under osmotic stress conditions. The TaWRKY76 protein targeted onto nucleus and possessed ability interacting with TaMYC2, a MYC TF member of wheat. TaWRKY76 and TaMYC2 positively regulated plant drought and salt adaptation by modulating osmotic stress-related physiological indices, including osmolyte contents, stomata movement, root morphology, and reactive oxygen species (ROS) homeostasis. Yeast one-hybrid assay indicated the binding ability of TaWRKY76 with promoters of TaDREB1;1, TaNCEB3, and TaCOR15;4. ChIP-PCR analysis confirmed that the osmotic stress genes are transcriptionally regulated by TaWRKY76. Moreover, the transgenic lines with knockdown of these stress-response genes displayed lowered plant biomass together with worsened root growth traits, decreased proline contents, and elevated ROS amounts. These results suggested that these stress defensive genes contributed to TaWRKY76-modulated osmotic stress tolerance. Highly positive correlations were observed between yield and the transcripts of TaWRKY76 in a wheat variety panel under field drought condition. A major haplotype TaWRKY76 Hap1 conferred improved drought tolerance. Our results suggested that TaWRKY76 is essential in plant drought and salt adaptation and a valuable target for molecular breeding stress-tolerant cultivars in Triticum aestivum L..

Genome-Wide Identification of WRKY Transcription Factors in Pea (Pisum sativum L.) and their Response to Sulfur and Water Stress

AbstractThe WRKY gene family is widely distributed in plants and plays essential roles in plant development and stress response. Despite extensive characterization of WRKY transcription factors in many plants, a genome-wide analysis of the WRKY gene family in Pisum sativum is still lacking. The central method of this study focused on the retrieval and characterization of WRKY gene sequences in the pea genome and further looking up for their modulation in response to sulfur and water stress. This involved a combination of bioinformatics tools and gene expression study to identify, characterize, and understand the properties of the WRKY gene family in pea. In this study, 86 PsWRKY genes were identified in the pea genome, categorized into five phylogenetic groups. They were dispersed across all seven chromosomes, with Chromosome 5 showing the highest enrichment. Synteny analysis revealed orthologs of 69 PsWRKY genes in Arabidopsis and Medicago. Transcriptome analysis identified 36 differentially expressed PsWRKY genes in response to sulfur (S) stress, water (W) stress, and their combination (W + S). Real-time PCR validation confirmed significant upregulation of PsWRKY23, PsWRKY58, PsWRKY64, and PsWRKY83 under water stress, PsWRKY58 and PsWRKY84 under sulfur stress, and PsWRKY03 under combined (W + S) stress. Overall, this study provides important insights on genetic information of the WRKY gene family in Pea and its possible role in water and sulfur stress, which will help further to study these candidate WRKY gene with a future objective of understanding their role in abiotic stress.

Identification of WRKY transcription factors in Rosa chinensis and analysis of their expression response to alkali stress response

Breeding abiotic stress-tolerant varieties of Rosa chinensis is a paramount goal in horticulture. WRKY transcription factors, pivotal in plant responses to diverse stressors, offer potential targets for enhancing stress resilience in R. chinensis. Using bioinformatics and genomic data, we identified RcWRKY transcription factor genes, characterised their chromosomal distribution, phylogenetic relationships, structural attributes, collinearity, and expression patterns in response to saline stress. Leveraging bidirectional database searches, we pinpointed 66 RcWRKY genes, categorised into three groups. All except RcWRKY60 encoded DNA Binding Domain and Zinc Finger Motif regions of the WRKY domain. Expansion of the RcWRKY gene family was propelled by 19 segmental, and 2 tandem, duplications. We unveiled 41 and 15 RcWRKY genes corresponding to 50 AtWRKY and 17 OsWRKY orthologs respectively, indicating postdivergence expansion. Expression analyses under alkaline stress pinpointed significant alterations in 54 RcWRKY genes. Integration of functional roles from their Arabidopsis orthologs and cis-acting elements within their promoters, along with quantitative reverse transcription PCR validation, underscored the importance of RcWRKY27 and 29 in R. chinensis’ alkaline stress response. These findings offer insights into the biological roles of RcWRKY transcription factors, as well as the regulatory dynamics governing R. chinensis’ growth, development, and stress resilience.

Regional propolis extracts suppress Fusarium fujikuroi and boost rice seedling growth and response against Bakanae disease

Bakanae, caused by Fusarium fujikuroi, is a serious seed-borne disease affecting rice production worldwide. Herein, we investigated the potential of propolis, a natural honeybee product, collected from three geographic locations in Egypt: North (Menofia), Middle (Cairo), and South (Sohag), and extracted with four different solvents (ethanol, olive oil, hexane, and water) as a sustainable eco-friendly alternative to control the Bakanae disease in rice. In vitro experiments showed that propolis extracts exhibited antifungal activity against F. fujikuroi and significantly suppressed its mycelial growth and sporulation. The antifungal activity of propolis extracts was associated with its chemical composition which varied depending on geographical origin, and the extraction solvents. Moreover, SEM-based analysis revealed that ethanolic extract of northern propolis prominently altered the microconidia morphology of F fujikuroi, which shrunken and seemed to lose their viability. These findings were further confirmed in vivo under greenhouse conditions. Soaking F fujikuroi-inoculated rice seeds in 1000 ppm of propolis extract significantly reduced the bakanae disease incidence, and disease severity index compared to mock-treated controls. Although infection with F fujikuroi induced the accumulation of H2O2, the application of propolis extracts alleviated oxidative stress and significantly reduced the H2O2 levels within infected rice seedlings. Moreover, propolis extracts enhanced the profile of enzymatic antioxidants (guaiacol-dependent peroxidase [POX] and polyphenol oxidase [PPO]) in F. fujikuroi-infected rice seedlings. Finally, Propolis extracts-treated rice seedlings exhibited higher transcript levels of three PTI-marker genes including nonexpressor of pathogenesis-related genes 1 (OsNPR1), WRKY transcription factor 21(OsWRKY21), and phenylalanine ammonia-lyase (OsPAL1), which are associated with systemic acquired resistance (SAR) and crucial for the plant's defense response against pathogens. Collectively, these findings suggest that propolis might be a promising sustainable, eco-friendly alternative to control bakanae disease and other fungal seed-borne phytopathogens due to its antifungal properties and ability to induce a complex multilayered defense system within infected plants.