Project 2
The molecular basis and functional contribution of Ca2+ signatures in plant-cell-autonomous immunity and during pathogen entry
Max-Planck-Institute for Plant Breeding Research, Cologne
Brief description in German:
In pflanzlichen und tierischen Zellen ist cytosolisches Calcium (Ca2+) ein wichtiges Signalmolekül, das an vielen biologischen Prozessen, inklusive zellautonomen Immunantworten und dem Eintritt von Mikroben in Wirtszellen, beteiligt ist. Die Identität von Proteinen, die einen Stimulus-vermittelten Einstrom von Ca2+ aus dem Extrazellularraum oder aus internen Speichern in das Cytoplasma und den Zellkern pflanzlicher Zellen erlauben, ist ungeklärt. Wir schlagen ein Projekt vor, um die molekulare Basis und den funktionalen Beitrag von Ca2+-Signaturen in pflanzlicher zellautonomer Immunität und während des Pathogeneintritts zu klären.
In plant and animal cells cytosolic calcium (Ca2+) is an important secondary messenger implicated in numerous biological processes, including cell-autonomous (innate) immune responses. For example, in both kingdoms transient increases in cytoplasmic Ca2+ levels (“Ca2+ signatures”) constitute a conserved immediate early event upon stimulation of immune responses, e.g. upon contact of cell surface receptors with pathogen/microbe-associated molecular patterns (PAMPs/MAMPs, here for simplicity referred to as PAMPs) or the activation of the human T cell receptor.
In addition to their role in immunity, Ca2+ signatures also play a role in pathogen invasion of mammalian cells and during the establishment of symbiotic plant-microbe interactions. The rise in cytosolic Ca2+ concentrations is the consequence of influx of Ca2+ ions from the extracellular environment or from internal stores such as the Endoplasmic Reticulum (ER) and the central plant vacuole. In mammalian cells, cytosolic Ca2+ is released following activation of cell surface receptors in a two-step process involving store-operated Ca2+ channels. Little is known about the functional contribution of Ca2+ signatures to plant cell-autonomous immunity or during pathogen entry into plant cells, and the plant components mediating stimulus-induced Ca2+ signatures remain elusive.
We will trace Ca2+ signatures in Arabidopsis MLO wild type and mlo mutant genotypes in interactions with adapted and non-adapted powdery mildew fungi. Additionally, we will exploit mutant collections available within the CRC to study Ca2+ signatures in a range of mutants that are defective in various aspects of PAMP- or effector-triggered cell-autonomous immunity. To identify components modulating Ca2+ signatures generated during biotic stress we propose a forward genetic screen based on the Förster Resonance Energy Transfer (FRET)-based Ca2+ sensor, Camaeleon, in combination with automated high-throughput confocal microscopy. Mutants with aberrant PAMP-triggered cytosolic and/or nuclear Ca2+ levels will be subjected to further detailed analysis and the gene(s) corresponding to interesting mutant(s) will be isolated by means of next-generation-based whole genome resequencing.
In addition to the forward genetic screen, we will conduct a chemical genetics screen to identify novel small molecular weight compounds that affect PAMP-triggered Ca2+ levels in plant cells. These genetic and pharmacological tools will allow us to rigorously assess the role of Ca2+ signatures in a broad range of cell-autonomous immune responses such as PAMP signalling, the control of host cell entry and with regard to nuclear activities of intracellular immune receptors and their signalling components.
List of publications resulting from the project
Peer-reviewed publications:
Kwaaitaal M, Huisman R, Maintz J, Reinstädler A, and Panstruga R (2011) Ionotropic gluatmate receptor (iGluR)-like channels mediate MAMP-induced calcium influx in Arabidopsis thaliana. Biochemical Journal 440: 355-365
Humphry M, Bednarek P, Kemmerling B, Koh S, Stein M, Göbel U, Stüber K, Pislewska-Bednarek M, Loraine A, Schulze-Lefert P, Somerville S, and Panstruga R (2010) A regulon conserved in monocot and dicot plants defines a functional module in antifungal plant immunity. PNAS 107: 21896-21901
Bednarek P, Pislewska-Bednarek M, Svatos A, Schneider B, Doubsky J, Mansurova M, Humphry M, Consonni C, Panstruga R, Sanchez-Vallet A, Molina A, Schulze-Lefert P (2009) A glucosinolate metabolism pathway in living plant cells mediates broad-spectrum antifungal defense. Science 323: 101-106
Panstruga R, Dodds PN (2009) Terrific protein traffic: The mystery of effector protein delivery by filamentous plant pathogens. Science 324: 748-750
Kwon C, Neu C, Pajonk S, Yun HS, Lipka U, Humphry M, Bau S, Straus M, Kwaaitaal M, Rampelt H, El Kasmi F, Jürgens G, Parker J, Panstruga R*, Lipka V*, Schulze-Lefert P* (2008) Co-option of a default secretory pathway for plant immune responses. Nature 451: 835-840 (* co-corresponding authors)
Kwon C, Panstruga R, Schulze-Lefert P (2008) Les liaisons dangereuses: immunological synapse formation in animals and plants. Trends in Immunology 29: 159-166
Pajonk S, Kwon C, Clemens N, Panstruga R, Schulze-Lefert P (2008) Activity determinants and functional specialization of Arabidopsis PEN1 syntaxin in innate immunity. Journal of Biological Chemistry 283: 26974-26984
Zappel NF, Panstruga R (2008) Heterogeneity and lateral compartmentalization of plant plasma membranes. Current Opinion in Plant Biology 11: 632-640
Non peer-reviewed publications:
Panstruga R, Parker JE, Schulze-Lefert P (2009) SnapShot: Plant Immune Response Pathways. Cell 136: 978-U976
Yun HS, Panstruga R, Schulze-Lefert P, Kwon C (2008) Ready to fire - secretion in plant immunity. Plant Signaling & Behavior 3: 505-508
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