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Project 24
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Project 24

Imre Edwin Somssich

Identification of nuclear components and in vivo target genes of the Arabidopsis transcription factors AtWRKY18/40 during early MAMP-triggered plant immunity

Max-Planck-Institute for Plant Breeding Research, Cologne


Brief description in German
Damit Wirtspflanzenzellen sich gegen Krankheitserreger wehren können, bedarf es einer massiven Umprogrammierung ihrer Genexpression. Eingeleitet wird dieser Prozess durch die Erkennung des Erregers und Weiterleiten dieser Information über zwei distinkte Signaltransduktionswege (“PAMP-Triggered Immunity” PTI, und “Effector-Triggered Immunity” ETI) in den Zellkern. Die Arabidopsis Transkriptionsfaktoren AtWRKY18 und AtWRKY40 sind negative PTI aber positive ETI Regulatoren. In diesem Projekt werden wir ein Gesamtprofil aller AtWRKY18 und AtWRKY40 Zielgene ermitteln und in Verbindung zu Transkriptionsveränderungen bringen. Durch weiterführende biochemische und genetische Studien wollen wir herausfinden welche Zielgene notwendig sind in PTI, und um Resistenz gegen den Mehltaupilz Golovinomyces orontii zu erreichen.

Massive transcriptional reprogramming within host plant cells is required to efficiently defend against diverse phytopathogens. Still, very little is known about the terminal nuclear-localized stages of the two major defense signaling pathways, namely PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI), leading to plant immunity.

WRKY-type transcription factors play a key role in modulating the plant defense transcriptome acting in a transcriptional network composed of positive and negative feedback loops and feed-forward modules. In Arabidopsis, loss-of-function mutants for two genes encoding partially redundantly acting WRKY factors, AtWRKY18 and AtWRKY40, render plants fully resistant towards the otherwise virulent powdery mildew pathogen Golovinomyces orontii.

This project aims at
1) uncovering nuclear components of PTI and ETI signaling that require functional interactions with the two closely related Arabidopsis WRKY transcription factors, AtWRKY18 and AtWRKY40, and
2) to define the early regulatory program of PTI within individual host cells.

AtWRKY18 and AtWRKY40 act redundantly as negative regulators of PTI, but also appear to function as key nuclear localized integrators of distinct host signals at the convergence point of both defense-signaling pathways. Applying massively parallel sequencing in combination with chromatin immunoprecipitation (ChIP-Seq) we plan to identify direct in vivo target genes of AtWRKY40 and AtWRKY18 on a global scale.


List of relevant publications

Liu, S., Ziegler, J., Zeier, J., Birkenbihl, R.P., Somssich, I.E. (2017). Botrytis cinerea B05.10 promotes disease development in Arabidopsis by suppressing WRKY33-mediated host immunity. Plant Cell Environ. 40, 2189-2206

Birkenbihl, R.P., Lui, S., and Somssich, I.E. 2017. Transcriptional events defining plant immune responses. Curr. Opin. Plant Biol. 38, 1-9

Birkenbihl, R.P., Kracher, B., Roccaro, M., and Somssich, I.E. 2017. Induced genome-wide binding of three WRKY transcription factors during early MAMP-triggered immunity. Plant Cell 29, 20-38.

Liu, S., Kracher, B., Ziegler, J., Birkenbihl, R.P., and Somssich, I.E. 2015. Negative regulation of ABA signaling by WRKY33 is critical for Arabidopsis immunity towards Botrytis cinerea 2100. eLIFE 4, e07295.

Tsuda, K., and Somssich, I.E. 2015. Transcriptional networks in plant immunity. New Phytol. 206, 932-947.

Lozano-Duran, R., Macho, A.P., Boutrot, F., Segonzac, C., Somssich, I.E., and Zipfel, C. 2013. The transcriptional regulator BZR1 mediates trade-off between plant innate immunity and growth. eLIFE 2, e00983

Schön, M., Töller, A., Diezel, C., Roth, C., Westphal, L., Wiermer, M., and Somssich, I.E. 2013. Analyses of wrky18 wrky40 plants reveal critical roles of SA/EDS1 signaling and indoleglucosinolate biosynthesis for G. orontii resistance and a loss-of-resistance towards Pto AvrRPS4. Mol. Plant-Microbe Interact. 26, 758-767

Logemann, E., Birkenbihl, R.P., Rawat, V., Schneeberger, K., Schmelzer, E. and Somssich, I.E. 2013. Functional dissection of the PROPEP2 and PROPEP3 promoters reveals the importance of WRKY factors in mediating MAMP-induced expression. New Phytol. 198, 1165-1177

Birkenbihl, R.P., Diezel, C. and Somssich. I.E. 2012. Arabidopsis WRKY33 is a key transcriptional regulator of hormone and metabolic response towards Botrytis cinerea infection. Plant Physiol. 159, 266-285, 2012.

Jordan, T., Seeholzer, S., Schwizer, S., Töller, A., Somssich, I.E., and Keller, B. 2011. The wheat Mla homologue TmMla1 exhibits an evolutionarily conserved function against powdery mildew in both wheat and barley. Plant J. 65, 610-621

Maekawa, T., Cheng, W., Spiridon, L.N., Töller, A., Lukasik, E., Saijo, Y., Liu, P., Shen, Q.-H., Micluta, M.A., Somssich, I.E., Takken, F.L.W., Petrescu, A.-J., Chai, J., and Schulze-Lefert P. 2011. Coiled-coil domain-dependent homodemerization of intracellular barley immune receptors defines a minimal functional module for triggering cell death, Cell Host & Microbe 9, 187-199

Roccaro, M., and Somssich, I.E. 2011. Chromatin immunoprecipitation (ChIP) to identify global targets of WRKY transcription factor family members involved in plant immunity. In Methods in Molecular Biology: Plant Immunity. J.M. McDowell, ed (Totowa, NJ) Humana Press Inc, 712, 45-58

Pandey, S.P., Roccaro, M., Schön, M., Logemann, E. and Somssich, I.E. 2010. Transcriptional reprogramming regulated by WRKY18 and WRKY40 facilitates powdery mildew infection in Arabidopsis. Plant J. 64. 912-923.

Rushton, P.J., Somssich, I.E.: Ringler, P., and Shen, Q.J. 2010. WRKY transcription factors. Trends Plant Sci. 15, 247-258

Somssich, I.E.: Networks of transcriptional regulation underlying plant defense responses towards phytopathogens. 2009. In Annual Plant Reviews 20 (ed. Grasser, K.D.). Oxford, UK: Blackwell Publishing, pp. 266-284, 2006.nt Physiol. 150, 1648-1655

Pandey, S.P. and Somssich, I.E. 2009. The role of WRKY transcription factors in plant immunity. Plant Physiol. 150,1648-55.

Ciolkowski, I., Wanke D., Birkenbihl R.P., Somssich I.E. 2008. Studies on DNA-binding selectivity of WRKY transcription factor lends structural clues into WRKY-domain function. Plant Mol. Biol. 68, 81-92.

Mukhtar, S.M., Deslandes, L., Auriac, M.-C., Marco, Y., and Somssich, I.E. 2008. The Arabidopsis transcription factor WRKY27 influences wilt disease symptom development caused by Ralstonia solanacearum. Plant J. 56, 935-947.

Eulgem, T., and Somssich, I.E. 2007. Networks of WRKY transcription factors in defense signaling. Curr. Opin. Plant Biol. 10, 366-371.

Lippok, B., Birkenbihl, R.P., Rivory, G., Brümmer, J., Schmelzer, E., Logemann, E., and Somssich, I.E. 2007. Expression of AtWRKY33 encoding a pathogen-/PAMP-responsive WRKY transcription factor is regulated by a composite DNA motif containing W box elements. Mol. Plant-Microbe Interact. 20, 420-429.

Shen, Q.-H., Saijo, Y., Mauch, S., Biskup, C., Bieri, S., Keller, B., Seki, H., Ulker, B., Somssich, I.E., and Schulze-Lefert, P. 2007. Nuclear activity of MLA immune receptors links isolate-specific and basal disease-resistance responses. Science 315, 1098-1103.

Ülker, B., Shahid Mukhtar, M., and Somssich, I. E. 2007. The WRKY70 transcription factor of Arabidopsis influences both the plant senescence and defense signaling pathways. Planta 226, 125-137.

Journot-Catalino, N., Somssich, I.E., Roby, D., and Kroj, T. 2006. The transcription factors WRKY11 and WRKY17 act as negative regulators of basal resistance in Arabidopsis thaliana. Plant Cell 18, 3289-3302.

Turck, F., Zhou, A., and Somssich, I.E. 2004. Stimulus-dependent, promoter-specific binding of transcription factor WRKY1 to its native promoter and the defense-related gene PcPR1-1 in parsley. Plant Cell 16, 2573-2585.

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