Post-translational regulation of WRKY transcription factors in plant immunity

Laboratory of Defense in Plant-Pathogen Interactions, Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan.
Current opinion in plant biology (Impact Factor: 7.85). 03/2012; 15(4):431-7. DOI: 10.1016/j.pbi.2012.02.003
Source: PubMed


Plants have evolved immune system to protect themselves against invading pathogens. Recent research has illustrated that signaling networks, after perception of diverse pathogen-derived signals, facilitate transcriptional reprogramming through mitogen-activated protein kinase (MAPK) cascades. WRKY proteins, which comprise a large family of plant transcription factors, are key players in plant immune responses. WRKY transcription factors participate in the control of defense-related genes either as positive or as negative regulators, and essentially are regulated at the transcriptional level. Emerging evidence emphasizes that group I WRKY transcription factors, which contain a conserved motif in the N-terminal region, are also activated by MAPK-dependent phosphorylation, underlining their importance in plant immunity.

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    • "Thus, these findings indicate that WRKY33 positively regulates ATL31 expression during plant defense responses. Since the activity of WRKY33 is regulated via phosphorylation by MAP kinases during pathogen signaling (Buscaill and Rivas 2014; Ishihama and Yoshioka 2012; Meng and Zhang 2013; Zhang et al. 2002), it suggests that upstream of the transcriptional regulation of ATL31 by WRKY33 may be regulated by MAP kinase signaling components after recognition of PAMPs and Pst. DC3000. "
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    ABSTRACT: ATL31, an Arabidopsis RING-type ubiquitin ligase, plays a critical role in plant carbon/nitrogen (C/N)-nutrient responses during post-germinative growth and in defense responses to pathogen attack. ATL31 expression under these stress conditions suggested the presence of transcriptional regulators mediated by these stress signals. We recently reported that the expression pattern of WRKY33, a transcription factor involved in plant defense responses, is highly correlated with that of ATL31. In this study, we investigated the detailed relationship between the ATL31 gene and WRKY33. Using transient reporter analysis, we found that WRKY33 could significantly activate ATL31 transcription in plant cells. Transcript analysis of stable transgenic Arabidopsis plants overexpressing WRKY33 confirmed that the expression of ATL31 in response to the PAMPs flg22 and chitin was enhanced compared with wild-type plants, while expression was repressed in wrky33 mutants. Further detailed transient reporter analysis revealed that transactivation by WRKY33 is required and mediated through a specific W-box cis-acting element in the promoter region of the ATL31 gene. In contrast, WRKY33 did not regulate ATL31 expression during the C/N response. Taken together, these results demonstrate that WRKY33 acts as a transcription factor of ATL31 and positively regulates its expression during activation of plant defense responses.
    Plant Biotechnology 01/2015; 32:11-19. DOI:10.5511/plantbiotechnology.14.1201b · 0.87 Impact Factor
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    • "Out of the four subfamilies of AP2/EREBP (i.e., AP2, RAV (related to ABI3/VP1), dehydration-responsive element-binding protein (DREB), and ERF) [45], [46], only the two largest ones, the DREB and ERF subfamilies, were deregulated in the lif2-1 mutant. The plant-specific WRKY transcription factors are key regulators of stress and plant immune responses [47], whereas the NAC TFs are involved in both development and the abiotic and/or biotic stress responses. Two stress-responsive NACs (SNACs) that were recently described [48], [49] were deregulated in the lif2-1 transcriptome. "
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    ABSTRACT: Eukaryotes have evolved complex defense pathways to combat invading pathogens. Here, we investigated the role of the Arabidopsis thaliana heterogeneous nuclear ribonucleoprotein (hnRNP-Q) LIF2 in the plant innate immune response. We show that LIF2 loss-of-function in A. thaliana leads to changes in the basal expression of the salicylic acid (SA)- and jasmonic acid (JA)- dependent defense marker genes PR1 and PDF1.2, respectively. Whereas the expression of genes involved in SA and JA biosynthesis and signaling was also affected in the lif2-1 mutant, no change in SA and JA hormonal contents was detected. In addition, the composition of glucosinolates, a class of defense-related secondary metabolites, was altered in the lif2-1 mutant in the absence of pathogen challenge. The lif2-1 mutant exhibited reduced susceptibility to the hemi-biotrophic pathogen Pseudomonas syringae and the necrotrophic ascomycete Botrytis cinerea. Furthermore, the lif2-1 sid2-2 double mutant was less susceptible than the wild type to P. syringae infection, suggesting that the lif2 response to pathogens was independent of SA accumulation. Together, our data suggest that lif2-1 exhibits a basal primed defense state, resulting from complex deregulation of gene expression, which leads to increased resistance to pathogens with various infection strategies. Therefore, LIF2 may function as a suppressor of cell-autonomous immunity. Similar to its human homolog, NSAP1/SYNCRIP, a trans-acting factor involved in both cellular processes and the viral life cycle, LIF2 may regulate the conflicting aspects of development and defense programs, suggesting that a conserved evolutionary trade-off between growth and defense pathways exists in eukaryotes.
    PLoS ONE 06/2014; 9(6):e99343. DOI:10.1371/journal.pone.0099343 · 3.23 Impact Factor
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    • "They are divided into 3 groups based on the number of WRKY domains present: 2 WRKY domains with a C2H2 zinc finger motif (group I); 1 WRKY domain with a C2H2 zinc finger motif (group II); and 1 WRKY domain with a C2H/C zinc finger motif (group III) [26]. In the N-terminal region of several group I WRKY proteins, multiple clustered serine-proline residues (SP cluster), which can be putatively phosphorylated by MAPKs, are highly conserved (Fig. S1) [27]–[30]. "
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    ABSTRACT: WRKY transcription factors and mitogen-activated protein kinase (MAPK) cascades have been shown to play pivotal roles in the regulation of plant defense responses. We previously reported that OsWRKY53-overexpressing rice plants showed enhanced resistance to the rice blast fungus. In this study, we identified OsWRKY53 as a substrate of OsMPK3/OsMPK6, components of a fungal PAMP-responsive MAPK cascade in rice, and analyzed the effect of OsWRKY53 phosphorylation on the regulation of basal defense responses to a virulence race of rice blast fungus Magnaporthe oryzae strain Ina86-137. An in vitro phosphorylation assay revealed that the OsMPK3/OsMPK6 activated by OsMKK4 phosphorylated OsWRKY53 recombinant protein at its multiple clustered serine-proline residues (SP cluster). When OsWRKY53 was coexpressed with a constitutively active mutant of OsMKK4 in a transient reporter gene assay, the enhanced transactivation activity of OsWRKY53 was found to be dependent on phosphorylation of the SP cluster. Transgenic rice plants overexpressing a phospho-mimic mutant of OsWRKY53 (OsWRKY53SD) showed further-enhanced disease resistance to the blast fungus compared to native OsWRKY53-overexpressing rice plants, and a substantial number of defense-related genes, including pathogenesis-related protein genes, were more upregulated in the OsWRKY53SD-overexpressing plants compared to the OsWRKY53-overexpressing plants. These results strongly suggest that the OsMKK4-OsMPK3/OsMPK6 cascade regulates transactivation activity of OsWRKY53, and overexpression of the phospho-mimic mutant of OsWRKY53 results in a major change to the rice transcriptome at steady state that leads to activation of a defense response against the blast fungus in rice plants.
    PLoS ONE 06/2014; 9(6):e98737. DOI:10.1371/journal.pone.0098737 · 3.23 Impact Factor
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