Sugarcane transcription factor ScWRKY4 negatively regulates resistance to pathogen infection through the JA signaling pathway

WRKY transcription factors,transcriptional regulators unique to plants,play an important role in defense response to pathogen infection.However,the resistance mechanisms of WRKY genes in sugarcane remain unclear.In the present study,gene ontology(GO)enrichment analysis revealed that WRKY gene family in sugarcane was extensively involved in the response to biotic stress and in defense response.We identified gene ScWRKY4,a classⅡc member of the WRKY gene family,in sugarcane cultivar ROC22.This gene was induced by salicylic acid(SA)and methyl jasmonate(MeJA)stress.Interestingly,expression of ScWRKY4 was down-regulated in smut-resistant sugarcane cultivars but up-regulated in smutsusceptible sugarcane cultivars infected with Sporisorium scitamineum.Moreover,stable overexpression of the ScWRKY4 gene in Nicotiana benthamiana enhanced susceptibility to Fusarium solani var.coeruleum and caused down-regulated expression of immune marker-related genes.Transcriptome analysis indicated suppressed expression of most JAZ genes in the signal transduction pathway.ScWRKY4 interacted with ScJAZ13 to repress its expression.We thus hypothesized that the ScWRKY4 gene was involved in the regulatory network of plant disease resistance,most likely through the JA signaling pathway.The present study depicting the molecular involvement of ScWRKY4 in sugarcane disease resistance lays a foundation for future investigation.

Sequence Analysis of Transcription Factor AtWRKY35 and Construction of Prokaryotic Expression Vector

As members of a super gene family, WRKY transcription factors are widely distributed in higher plants. ln this study, bioinformatic analysis of WRKY35, a member of the WRKY gene family, was carried out. Results indicated that tran-scription factor WRKY35 harbors a WRKYGQK core domain and a Cys2His2 or Cys2His/Cys zinc finger in the 5’ end without transmembrane domain. After PCR amplification and restriction digestion, WRKY35 gene fragment was ligated to prokaryotic expression vector PET28. This study provided basis for expression anal-ysis of WRKY35 protein and subsequent functional identification of WRKY35 gene.

Identification of yellowhorn(Xanthoceras sorbifolium)WRKY transcription factor family and analysis of abiotic stress response model

WRKY transcription factors are widely distributed in higher plants and play important roles in many biological processes,including stress resistance.The recently published genome sequence of yellowhorn,an oil tree with robust resistance to cold,drought,heat,salt and alkali,provides an excellent opportunity to identify and characterize the entire yellowhorn WRKY protein family and a basis for the study of abiotic stress resistance of WRKY gene family in forest species.In the present comprehensive analysis of WRKY transcription factors in yellowhorn,65 WRKY genes were identified and defined based on their location on the chromosome.According to their structure and phylogenetic relationships,XsWRKY genes clustered into WRKY groupsⅠ-Ⅲ.Segmental duplication events played a significant role in the expansion of WRKY gene family.Furthermore,transcriptomic data and real-time quantitative PCR analysis showed that expression of XsWRKY genes responding to salt and drought stresses and a hormone treatment.We also determined structures of the encoded proteins,c is-elements of the promoter region,and expression patterns.These results provide a foundation for the study of the biological function of WRKY transcription factors in yellowhorn.

Isolation and Expression Patterns of Rice WRKY82 Transcription Factor Gene Responsive to Both Biotic and Abiotic Stresses

WRKY transcription factors are involved in the regulation of response to biotic and abiotic stresses in plants. A full-length cDNA clone of rice WRKY82 gene （OsWRKY82） was isolated from a cDNA library generated from leaves infected by Magnaporthe grisea. OsWRKY82 contained an entire open reading frame in length of 1 701 bp, and was predicted to encode a polypeptide of 566 amino acid residues consisting of two WRKY domains, each with a zinc finger motif of C2H2, belonging to the WRKY subgroup I. OsWRKY82 shared high identity at the amino acid level with those from Sorghum bicolor, Hordeum vulgare, and Zea mays. The transcript level of OsWRKY82 was relatively higher in stems, leaves, and flowers, and less abundant in grains. It was induced by inoculation with M. grisea and Rhizoctonia solani. However, the inducible expression in incompatible rice-M. grisea interactions was earlier and greater than that in compatible interactions. The expression of OsWRKY82 was up-regulated by methyl jasmonate and ethephon, whereas salicylic acid exerted no effects on its expression. Moreover, OsWRKY82 exhibited transcriptional activation ability in yeast. Additionally, OsWRKY82 transcripts could be induced by wounding and heat shocking, but not by abscisic acid, cold, high salinity and dehydration. By contrast, gibberellin suppressed the expression of OsWRKY82. These indicate that OsWRKY82 is a multiply stress-inducible gene responding to both biotic and abiotic stresses, and may be involved in the regulation of defense response to pathogens and tolerance against abiotic stresses by jasmonic acid/ethylene-dependent signaling pathway.

GhWRKY75 positively regulates GhPR6-5b via binding to a W-box TTGAC(C/T)to orchestrate cotton resistance to Verticillium dahliae

Verticillium dahliae is an important fungal pathogen affecting cotton yield and quality.Therefore,the mining of V.dahlia-resistance genes is urgently needed.Proteases and protease inhibitors play crucial roles in plant defense responses.However,the functions and regulatory mechanisms of the protease inhibitor PR6 gene family remain largely unknown.This study provides a comprehensive analysis of the PR6 gene family in the cotton genome.We performed genome-wide identification and functional characterization of the cotton GhPR6 gene family,which belongs to the potato protease inhibitor I family of inhibitors.Thirty-nine PR6s were identified in Gossypium arboreum,G.raimondii,G.barbadense,and G.hirsutum,and they were clustered into four groups.Based on the analysis of pathogen-induced and Ghlmm transcriptome data,Gh PR6-5b was identified as the key gene for V.dahliae resistance.Virus-induced gene silencing experiments revealed that cotton was more sensitive to V.dahliae V991after PR6-5b silencing.The present study established that GhWRKY75 plays an important role in resistance to Verticillium wilt in cotton by positively regulating GhPR6-5b expression by directly binding to the W-box TTGAC(T/C).Our findings established that GhWRKY75 is a potential candidate for improving cotton resistance to V.dahliae,and provide primary information for further investigations and the development of specific strategies to bolster the defense mechanisms of cotton against V.dahliae.

WRKY11 up-regulated dirigent expression to enhance lignin/lignans accumulation in Lilium regale Wilson during response to Fusarium wilt

Lilium are highly economically valuable ornamental plants that are susceptible to Fusarium wilt caused by Fusarium oxysporum.Lilium regale Wilson,a wild lily native to China,is highly resistant to F.oxysporum.In this study,a WRKY transcription factor,WRKY11,was isolated from L.regale,and its function during the interaction between L.regale and F.oxysporum was characterized.The ectopic expression of LrWRKY11 in tobacco increased the resistance to F oxysporum,moreover,the transcriptome sequencing and UHPLC-MS/MS analysis indicated that the methyl salicylate and methyl jasmonate levels rose in LrWRKY11 transgenic tobacco,meanwhile,the expression of lignin/lignans biosynthesis-related genes including a dirigent(DiR)was up-regulated.The lignin/lignans contents in LrWRKY11-transgenic tobacco also significantly increased compared with the wild-type tobacco.In addition,the resistance of L.regale scales in which LrWRKY11 expression was silenced by RNAi evidently decreased,and additionally,the expression of lignin/lignans biosynthesis-related genes including LrDIR1 was significantly suppressed.Therefore,LrDIR1 and its promoter(PLrDIR1)sequence containing the W-box element were isolated from L.regale.The interaction assay indicated that LrWRKY11 specifically bound to the W-box element in PLrDIR1 and activated LrDIR1 expression.Additionally,β-glucuronidase activity in the transgenic tobacco co-expressing LrWRKY11/PLrDIR1-β-glucuronidase was higher than that in transgenic tobacco expressing PLrDIR1-β-glucuronidase alone.Furthermore,the ectopic expression of LrDIR1 in tobacco enhanced the resistance to F.oxysporum and increased the lignin/lignans accumulation.In brief,this study revealed that LrWRKY11 positively regulated L.regale resistance to F.oxysporum through interaction with salicylic acid/jasmonic acid signaling pathways and modulating LrDIR1 expression to accumulate lignin/lignans.

Identification of the target genes of AhTWRKY24 and AhTWRKY106 transcription factors reveals their regulatory network in Arachis hypogaea cv.Tifrunner using DAP-seq

WRKY transcription factors(TFs)have been identified as important core regulators in the responses of plants to biotic and abiotic stresses.Cultivated peanut(Arachis hypogaea)is an important oil and protein crop.Previous studies have identified hundreds of WRKY TFs in peanut.However,their functions and regulatory networks remain unclear.Simultaneously,the AdWRKY40 TF is involved in drought tolerance in Arachis duranensis and has an orthologous relationship with the AhTWRKY24 TF,which has a homoeologous relationship with AhTWRKY106 TF in A.hypogaea cv.Tifrunner.To reveal how the homoeologous AhTWRKY24 and AhTWRKY106 TFs regulate the downstream genes,DNA affinity purification sequencing(DAP-seq)was performed to detect the binding sites of TFs at the genome-wide level.A total of 3486 downstream genes were identified that were collectively regulated by the AhTWRKY24 and AhTWRKY106 TFs.The results revealed that W-box elements were the binding sites for regulation of the downstream genes by AhTWRKY24 and AhTWRKY106 TFs.A gene ontology enrichment analysis indicated that these downstream genes were enriched in protein modification and reproduction in the biological process.In addition,RNA-seq data showed that the AhTWRKY24 and AhTWRKY106 TFs regulate differentially expressed genes involved in the response to drought stress.The AhTWRKY24 and AhTWRKY106 TFs can specifically regulate downstream genes,and they nearly equal the numbers of downstream genes from the two A.hypogaea cv.Tifrunner subgenomes.These results provide a theoretical basis to study the functions and regulatory networks of AhTWRKY24 and AhTWRKY106 TFs.

Heat-inducible SlWRKY3 confers thermotolerance by activating the SlGRXS1 gene cluster in tomato

High temperature stress is one of the major environmental factors that affect the growth and development of plants. Although WRKY transcription factors play a critical role in stress responses, there are few studies on the regulation of heat stress by WRKY transcription factors,especially in tomato. Here, we identified a group I WRKY transcription factor, SlWRKY3, involved in thermotolerance in tomato. First, SlWRKY3 was induced and upregulated under heat stress. Accordingly, overexpression of SlWRKY3 led to an increase, whereas knock-out of SlWRKY3 resulted in decreased tolerance to heat stress. Overexpression of SlWRKY3 accumulated less reactive oxygen species(ROS), whereas knock-out of SlWRKY3 accumulated more ROS under heat stress. This indicated that SlWRKY3 positively regulates heat stress in tomato. In addition,SlWRKY3 activated the expression of a range of abiotic stress-responsive genes involved in ROS scavenging, such as a SlGRXS1 gene cluster.Further analysis showed that SlWRKY3 can bind to the promoters of the SlGRXS1 gene cluster and activate their expression. Collectively, these results imply that SlWRKY3 is a positive regulator of thermotolerance through direct binding to the promoters of the SlGRXS1 gene cluster and activating their expression and ROS scavenging.

Cloning of WRKY2 Gene in Tomato

[Objective]The aim was to explore the function of WRKY transcription factor in tomato.[Method]The primers were designed in this study according to the obtained WRKY fragments,and the total RNA from tomato treated with 100 μmol/L of JA for 6 h was used as the template for RT-PCR.[Result]The 608 bp fragment was obtained from tomato with RT-PCR method.Sequence analysis indicated that this sequence contained WRKYGQK conservative domain and the similarity with Capsicum annuum WRKY-c and Nicotiana tabacum NtWRKY-7 were 79% and 74%,respectively.[Conclusion]WRKY gene sequence in tomato was cloned successfully.

Constitutive expression of pathogen-inducible OsWRKY31 enhances disease resistance and affects root growth and auxin response in transgenic rice plants

WRKY transcription factors have many regulatory roles we isolated a rice WRKY gene （OsWRKY31） that is induced in response to biotic and abiotic stresses. In this study, by the rice blast fungus Magnaporthe grisea and auxin. This gene encodes a polypeptide of 211 amino-acid residues and belongs to a subgroup of the rice WRKY gene family that probably originated after the divergence of monocot and dicot plants. OsWRKY31 was found to be localized to the nucleus of onion epidermis cells to transiently express OsWRKY31-eGFP fusion protein. Analysis of OsWRKY31 and its mutants fused with a Gal4 DNA-binding domain indicated that OsWRKY31 has transactivation activity in yeast. Overexpression of the OsWRKY31 gene was found to enhance resistance against infection with M. grisea, and the transgenic lines exhibited reduced lateral root formation and elongation compared with wild-type and RNAi plants. The lines with overexpression showed constitutive expression of many defense-related genes, such as PBZI and OsSci2, as well as early auxin-response genes, such as OslAA4 and OsCrll genes. Furthermore, the plants with overexpression were less sensitive to exogenously supplied IBA, NAA and 2,4-1） at high concentrations, suggesting that overexpression of the OsWRKY31 gene might alter the auxin response or transport. These results also suggest that OsWRKY31 might be a common component in the signal transduction pathways of the auxin response and the defense response in rice.

The expression and binding properties of the rice WRKY68 protein in the Xa21-mediated resistance response to Xanthomonas oryzae pv. Oryzae

Plant WRKY transcription factors are involved in various physiological processes, including biotic and abiotic stress responses, as well as developmental processes. In this study, the expression patterns of the WRKY68 protein during interactions between rice 4021 containing the bacterial blight resistance gene Xa21 and Xanthomonas oryzae pv. oryzae（Xoo） were investigated. A possible modified form of the WRKY68 protein appeared in the Xa21-mediated disease resistance response, and its expression levels were similar in compatible and incompatible responses, but differed significantly from that of the mock control treatment, suggesting that WRKY68 may be involved in the bacterial blight response in rice. To further understand WRKY68＇s roles in the resistance signaling pathway, WRKY68 recombinant protein was expressed in Escherichia coli and a microscale thermophoresis analysis was performed to investigate the interactions between WRKY68 and cis-elements in crucial pathogenesis-related（PR） genes. The results showed that the WRKY68 protein binds to W-boxes in the PR1 b promoter region, with an apparent dissociation constant of 25 nmol L–1, while the binding between WRKY68 and PR10 a was W-box independent. The results suggested that a possible modified form of the WRKY68 protein was induced during the interaction between rice and Xoo, which then regulated the activity of the downstream PR genes by binding with the W-boxes in the PR1 b gene＇s promoter region. Moreover, the constitutive transcription of the WRKY68 gene in dozens of rice tissues and the expression of the WRKY68 protein in leaves during all growth stages suggests that WRKY68 plays important roles in rice during normal growth processes.

Differential Expression of Rice Valine-Qlutamine Gene Family in Response to Nitric Oxide and Regulatory Circuit of OsVQ7 and OsWRKY24

The functional diversity of plant valine-qlutamine(VQ) proteins is closely associated with their partners WRKY transcription factors, and also with a complex network of signaling pathways that mediated by hormone molecules. We reported genome-wide expression profiles of differentially expressed rice VQ genes under nitric oxide(NO) treatment based on a microarray analysis. Cluster analysis of expression patterns revealed that some VQ genes and WRKY genes shared similar expression trends. Prediction of cis-elements showed that W-box or W-box-like sequences were overrepresented within the promoters of most of NO-responsive VQ genes. In particular, the similarly expressed Os VQ7 and Os WRKY24 showed great induction upon NO triggering. Transient expression assay and chromatin immunoprecipitation analysis demonstrated that OsWRKY24 was specifically bound to the promoter regions of Os VQ7 and Os WRKY24 itself, which contain multiple copies of W-box or W-box-like cis-elements. Yeast-two-hybrid assay indicated that OsWRKY24 can interact physically with OsVQ7 through the C-terminal of WRKY domain. The results suggested that OsVQ7 and OsWRKY24 may form an auto-and cross-regulation circuit that is required for tight regulation and fine-tuning of physiological processes they are involved in. These findings provided a solid foundation for exploring the specific functions of the VQ protein family in NO signaling pathway.

Cloning and Expression Analysis of THWRKY12 Gene from Tamarix hispida

[ Objective] This study aimed to clone and analyze the expression of THWRKY12 gene in Tamarix hispida. [Method] T. hispida seedlings were treated with 400 mmol/L NaC1 solutlon, 20% PEG and 100 μmol/L ABA, respectively. The expression of THIVRKY12 gene in different tissues was investigated by RT-PCR technology. [Result] Under treatments of NaC1 and PEG, the expression of THWRKY12 gene in different tissues of T. h/sp/da seedlings showed an overall upregulated trend, suggesting that THWRKYI2 is related with the saline-alkali resistance and drought resistance of T. hispida. Under ABA treatment, THWRKY12 gene had approximately the same expression pattern with the former two, indicating that THWRKY12 gene may involve in the regulation and control of the saline-al- kali resistance and drought resistance of T. hispida through the signal pathway regulated by ABA. [ Conclusion] This study laid foundation for investigating the functions of WRKY gene in the stress resistance of T. hispida.

Cloning of the ZoWRKY1 Gene and its Correlation with 6-gingerol Biosynthesis in Zingiber officinale Roscoe

Ginger(Zingiber officinale Roscoe)has high economic value as medicinal and food resources.6-gingerol is the core medicinal constituents of ginger.In the present study,a local ginger cultivar of Chongqing was taken as the research material.The ZoWRKY1 gene was cloned to determine its expression level in different ginger developmental phases and to analyze its correlation with 6-gingerol content.The expression level of ZoWRKY1 under different concentrations of NaCl stress was tested,and so was the correlation between ZoWRKY1’s expression level and the contents of 6-gingerol synthase genes,i.e.ZoPAL,ZoC4H and Zo4CL.The results showed that the cDNA of the cloned ZoWRKY1 gene is 1026 bp in total length,and ZoWRKY1 belongs to the second type member of the WRKY family;the expression level of ZoWRKY1 rose sharply in the second developmental phase of the ginger which was about one month after sowing,and there was a significant correlation between the expression level of ZoWRKY1 and the increase of 6-gingerol content;the expressions of ZoWRKY1 and 6-gingerol synthase genes ZoPAL,ZoC4H and Zo4CL had sharp rises under 25 g/L NaCl stress,and the expression level of ZoWRKY1 was closely related to that of ZoC4H or Zo4CL.Therefore,it was speculated that there was a regulatory correlation between ZoWRKY1 and ZoC4H or Zo4CL that can further affect the biosynthesis of 6-gingerol.

FaSnRK1a mediates salicylic acid pathways to enhance strawberry resistance to Botrytis cinerea

Strawberry is a major fruit crop worldwide because its nutritional and health benefits to human health,but its productivity is limited by Botrytis cinerea.Sucrose nonfermentation 1-related protein kinase 1(SnRK1)has a defense function against pathogens,but the function of SnRK1 in the defense response to B.cinerea in plants is still unclear.In this study,FaSnRK1a-OE and RNAi fruits were constructed and then inoculated with B.cinerea.The result reveals a positive role of Fa SnRK1a in the regulation of resistance to gray mold.FaSnRK1a affects SA content by regulating FaPAL1 and FaPAL2 expressions.The genes related to the SA signaling pathway(FaTGA1 and FaTGA2.1)were significantly increased/decreased in FaSnRK1a-OE or FaSnRK1a-RNAi fruit,respectively.FaSnRK1a interacted with the FaWRKY33.2 protein and negatively regulated FaWRKY33.2 expression,and FaWRKY33.2 acts as a repressor of disease resistance to B.cinerea.Finally,FaSnRK1a regulates the expression of six PR genes and the activities of antioxidant enzymes to boost defense response after B.cinerea inoculation.Our findings showed that FaSnRK1a increases the resistance of strawberry fruit to B.cinerea via SA signaling pathway and interaction with the FaWRKY33.2 transcription factor.

Protein-Protein Interactions in the Regulation of WRKY Transcription Factors

It has been almost 20 years since the first report of a WRKY transcription factor, SPF1, from sweet potato. Great progress has been made since then in establishing the diverse biological roles of WRKY transcription factors in plant growth, development, and responses to biotic and abiotic stress. Despite the functional diversity, almost all ana-lyzed WRKY proteins recognize the TrGACC/T W-box sequences and, therefore, mechanisms other than mere recognition of the core W-box promoter elements are necessary to achieve the regulatory specificity of WRKY transcription factors. Research over the past several years has revealed that WRKY transcription factors physically interact with a wide range of proteins with roles in signaling, transcription, and chromatin remodeling. Studies of WRKY-interacting proteins have provided important insights into the regulation and mode of action of members of the important family of transcrip-tion factors. It has also emerged that the slightly varied WRKY domains and other protein motifs conserved within each of the seven WRKY subfamilies participate in protein-protein interactions and mediate complex functional interactions between WRKY proteins and between WRKY and other regulatory proteins in the modulation of important biologi- cal processes. In this review, we summarize studies of protein-protein interactions for WRKY transcription factors and discuss how the interacting partners contribute, at different levels, to the establishment of the complex regulatory and functional network of WRKY transcription factors.

Arabidopsis WRKY Transcription Factors WRKY12 and WRKY13 Oppositely Regulate Flowering under Short-Day Conditions

In plants, photoperiod is an important cue for determining flowering. The floral transition in Arabidopsis thaliana is earlier under long-day （LD） than under short-day （SD） conditions. Flowering of Arabidopsis plants under SD conditions is mainly regulated by the plant hormone gibberellin （GA）. Here, we report two WRKY transcription factors function oppositely in controlling flowering time under SD conditions. Phenotypic analysis showed that disruption of WRKY12 caused a delay in flowering, while loss of WRKY13 function promoted flowering. WRKY12 and WRKY13 displayed negatively correlated expression profiles and function successively to regulate flowering. Molecular and genetic analyses demonstrated that FRUITFULL （FUL） is a direct downstream target gene of WRKY12 and WRKY13. Interestingly, we found that DELLA proteins GIBBERELLIN INSENSITIVE （GAI） and RGA-LIKE1 （RGL1） interacted with WRKY12 and WRKY13, and their interactions interfered with the transcriptional activity of the WRKY12 and WRKY13. Further studies suggested thatWRKY12 and WRKY13 partly mediated the effect of GA3 on controlling flowering time. Taken together, our results indicate that WRKY12 and WRKY13 oppositely modulate flower- ing time under SD conditions, which at least partially involves the action of GA.

WRKY transcription factors down-regulate the expression of H2S-generating genes, LCD and DES in Arabidopsis thaliana

Hydrogen sulfide(H2S) is a gasotransmitter playing a vital role in response to biotic and abiotic stress for plants. In order to understand the transcriptional regulation of the genes that are responsible for endogenous H2 S generation, the promoter sequences of L-cysteine desulfhydrase(LCD), D-cysteine desulfhydrase(DCD1,DCD2), desulfhydrase(DES) and nitrogen fixation synthetase(NFS1, NFS2) were analyzed. They are all found to contain a W-box, a characteristic core binding site for the plant WRKY transcription factors, which have important roles in the plant's responses to numerous stresses by modifying the expression patterns of their target genes. An electrophoretic mobility shift assay indicated that WRKY18 and WRKY60 interacted with the W-box in the promoters of the LCD, DCD1, DCD2, DES and NFS2 genes, whereas WRKY40 bound to the W-box of the NFS1 promoter. The expression levels of the LCD, DES and DCD1 genes were up-regulated, but the DCD2 was downregulated in the plants with WRKY18, WRKY40 or WRKY60 mutations. The plants with double and triple mutations of WRKY18, WRKY40 and WRKY60 had a higher rate of H2 S production during cadmium stress and were more resistant to the cadmium stress than the wild type or single mutants. These results suggest that WRKY transcription factors regulate the H2 S signaling pathway in plants, allowing them to cope with cadmium stress.

Molecular Characterization of a Leaf Senescence-Related Transcription Factor BrWRKY75 of Chinese Flowering Cabbage

WRKY is a plant-specific transcription factor(TF) involved in the regulation of many biological processes; however, its role in leaf senescence of leafy vegetables remains unknown. In the present work, a WRKY TF, termed Br WRKY75 was isolated from Chinese flowering cabbage [Brassica rapa L. ssp. chinensis(L.) Mokino var. utilis Tsen et Lee]. Analysis of deduced amino acid sequence and the phylogenetic tree showed that Br WRKY75 has high homology with WRKY75 from Brassica oleracea and Arabidopsis thaliana, and belongs to the II c sub-group. Sub-cellular localization and transcriptional activity analysis revealed that Br WRKY75 is a nuclear protein with transcriptional repression activity, and was up-regulated during leaf senescence. Electrophoretic mobility shift assay confirmed that Br WRKY75 directly bound to the W-box(TTGAC) cis-element. Collectively,these results provide a basis for further investigation of the transcriptional regulation of Chinese flowering cabbage leaf senescence.

WRKY transcription factors in plant responses to stresses

The WRKY gene family is among the largest families of transcription factors （TFs） in higher plants. By regulating the plant hormone signal transduction pathway, these TFs play critical roles in some plant processes in response to biotic and abiotic stress, Various bodies of research have demonstrated the important biological functions of WRKY TFs in plant response to different kinds of biotic and abiotic stresses and working mecha- nisms. However, very li2ttle summarization has been done to review their research progress. Not iust important TFs function in plant response to biotic and abiotic stresses, WRKY also participates in carbohydrate synthesis, senes- cence, development, and secondary metabolites synthesis. WRKY proteins can bind to W-box （TGACC （A/T）） in the promoter of its target genes and activate or repress the expression of downstream genes to regulate their stress response. Moreover, WRKY proteins can interact with other TFs to regulate plant defensive responses. In the present review, we focus on the structural characteristics of WRKY TFs and the research progress on their functions in plant responses to a variety of stresses.