Stefanie Ranf

Stefanie Ranf
Technische Universität München | TUM · Phytopathology

PhD

About

33
Publications
9,204
Reads
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2,045
Citations
Introduction
Both, animals and plants sense invading pathogens through conserved microbe-associated molecular patterns (MAMPs), by specific host pattern-recognition receptors (PRRs) and trigger innate immune responses. Lipopolysaccharide (LPS) of gram-negative bacterial cell walls strongly activates several immune receptors in mammals. LPS also triggers immune defences in plants. We have recently identified a key component of LPS signalling, the receptor-like kinase LORE (LipoOligosaccharide-specific Reduced Elicitation). As a highly restrictive barrier, LPS is also an important virulence factor. In my current projects, I want to characterize the properties of LPS as stimulator of plant immunity and its role as virulence factor during plant infection.
Additional affiliations
May 2011 - December 2012
Leibniz Institute for Plant Biochemistry
Position
  • PostDoc Position
January 2005 - April 2011
Leibniz Institute for Plant Biochemistry
Position
  • PhD Student
Education
January 2005 - April 2011
Leibniz Institute for Plant Biochemistry
Field of study
  • Calcium signalling in plant innate immunity
October 1998 - February 2003
Universität Regensburg
Field of study
  • Biochemistry

Publications

Publications (33)
Article
Full-text available
Pseudomonas species infect a variety of organisms, including mammals and plants. Mammalian pathogens of the Pseudomonas family modify their lipid A during host entry to evade immune responses and to create an effective barrier against different environments, for example by removal of primary acyl chains, addition of phosphoethanolamine (P-EtN) to p...
Article
Full-text available
Plant innate immunity is activated upon perception of invasion pattern molecules by plant cell-surface immune receptors. Several bacteria of the genera Pseudomonas and Burkholderia produce rhamnolipids (RLs) from l -rhamnose and ( R )-3-hydroxyalkanoate precursors (HAAs). RL and HAA secretion is required to modulate bacterial surface motility, biof...
Preprint
Full-text available
Perception and processing of various internal and external signals is essential for all living organisms. Plants have an expanded and diversified repertoire of cell surface-localized receptor-like kinases (RLKs) that transduce signals across the plasma membrane. RLKs often assemble into higher-order receptor complexes with co-receptors, regulators...
Preprint
Full-text available
Background Plant cell-surface receptors sense various ligands to regulate physiological processes. Matching ligand-receptor pairs requires evidence of their direct interaction and is often a bottleneck in functional receptor studies. The S-domain-type (SD) pattern recognition receptor LORE senses medium chain-3-hydroxy fatty acids (mc-3-OH-FAs) suc...
Article
Full-text available
Lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria, is important for bacterial viability in general and host–pathogen interactions in particular. Negative charges at its core oligosaccharide (core-OS) contribute to membrane integrity through bridging interactions with divalent cations. The molecular struct...
Preprint
Full-text available
Plant innate immunity is activated upon perception of invasion pattern molecules by plant cell-surface immune receptors. Several bacteria of the genera Pseudomonas and Burkholderia produce rhamnolipids (RLs) from L- rhamnose and ( R )-3-hydroxyalkanoate precursors (HAAs). RL and HAA secretion is required to modulate bacterial surface motility, biof...
Article
Fusarium spp. cause severe economic damage in many crops, exemplified by Panama Disease of banana or Fusarium head blight of wheat. Plants sense immunogenic patterns (termed elicitors) at the cell surface to initiate pattern‐triggered immunity (PTI). Knowledge of fungal elicitors and corresponding plant immune‐signaling is incomplete but could yiel...
Article
Changes in cellular calcium levels are one of the earliest signalling events in plants exposed to pathogens or other exogenous factors. In a genetic screen, we identified an Arabidopsis thaliana ‘changed calcium elevation 1’ (cce1) mutant with attenuated calcium response to the bacterial flagellin flg22 peptide and several other elicitors. Whole ge...
Article
Full-text available
Despite its importance for membrane stability and pathogenicity of mammalian pathogens, functions of the O‐polysaccharide (OPS) of lipopolysaccharide (LPS) remain unclear in plant‐associated bacteria. Genetic information about OPS biosynthesis in these bacteria is largely missing. Genome analysis of various plant‐associated Pseudomonas strains reve...
Preprint
Full-text available
Fusarium is a genus of fungi causing severe economic damage in many crop species exemplified by Fusarium Head Blight of wheat or Panama Disease of banana. Plants sense immunogenic patterns (termed elicitors) at the cell surface contributing to disease resistance via the activation of pattern-triggered immunity (PTI). Knowledge of such elicitors or...
Article
In plants, cell-surface immune receptors sense molecular non-self-signatures. Lipid A of Gram-negative bacterial lipopolysaccharide is considered such a non-self-signature. The receptor kinase LIPOOLIGOSACCHARIDE-SPECIFIC REDUCED ELICITATION (LORE) mediates plant immune responses to Pseudomonas and Xanthomonas but not enterobacterial lipid A or lip...
Article
Full-text available
Infestations of crop plants with pathogens pose a major threat to global food supply. Exploiting plant defense mechanisms to produce disease-resistant crop varieties is an important strategy to control plant diseases in modern plant breeding and can greatly reduce the application of agrochemicals. The discovery of different types of immune receptor...
Article
Full-text available
In Gram-negative bacteria, the cell envelope largely consists of lipopolysaccharide (LPS), a class of heterogeneous glycolipids. As a fundamental component of the outer membrane, LPS provides stability to the bacterial cell and forms a protective cover shielding it from hostile environments. LPS is not only fundamental to bacterial viability, but a...
Article
In plants, sensing of Pathogen/Microbe-Associated Molecular Patterns (PAMPs/MAMPs) and host-derived Damage-Associated Molecular Patterns (DAMPs) by host cell surface Pattern Recognition Receptors (PRRs) activates Pattern-Triggered Immunity (PTI). The identification of an increasing number of immunogenic patterns and PRRs illustrates that PTI is a u...
Article
Orchestration of cellular behavior in plant organogenesis requires integration of intercellular communication and cell wall dynamics. The underlying signaling mechanisms are poorly understood. Tissue morphogenesis in Arabidopsis depends on the receptor-like kinase STRUBBELIG. Mutations in ZERZAUST were previously shown to result in a strubbelig-lik...
Article
Full-text available
Defense of attempted infection depends on the host’s ability to sense invading pathogens and rapidly activate immune responses. Pathogens, in turn, use a repertoire of evasion strategies and virulence factors to circumvent the host’s surveillance and defense systems. Lipopolysaccharide (LPS), a complex glycolipid covering the cell surface of gram-n...
Article
Full-text available
RHO GTPases are regulators of cell polarity and immunity in eukaryotes. In plants, RHO-like RAC/ROP GTPases are regulators of cell shaping, hormone responses, and responses to microbial pathogens. The barley (Hordeum vulgare L.) RAC/ROP protein RACB is required for full susceptibility to penetration by Blumeria graminis f.sp. hordei (Bgh), the barl...
Chapter
Full-text available
Ca2+ is a secondary messenger involved in early signaling events triggered in response to a plethora of biotic and abiotic stimuli. In plants, environmental cues that induce cytosolic Ca2+ elevation include touch, reactive oxygen species, cold shock, and salt or osmotic stress. Furthermore, Ca2+ signaling has been implicated in early stages of plan...
Article
Full-text available
Background: Calcium, as a second messenger, transduces extracellular signals into cellular reactions. A rise in cytosolic calcium concentration is one of the first plant responses after exposure to microbe-associated molecular patterns (MAMPs). We reported previously the isolation of Arabidopsis thaliana mutants with a "changed calcium elevation"...
Article
Full-text available
The sensing of microbe-associated molecular patterns (MAMPs) triggers innate immunity in animals and plants. Lipopolysaccharide (LPS) from Gram-negative bacteria is a potent MAMP for mammals, with the lipid A moiety activating proinflammatory responses via Toll-like receptor 4 (TLR4). Here we found that the plant Arabidopsis thaliana specifically s...
Article
Full-text available
Background Plant perception of conserved microbe-derived or damage-derived molecules (so-called microbe- or damage-associated molecular patterns, MAMPs or DAMPs, respectively) triggers cellular signaling cascades to initiate counteracting defence responses. Using MAMP-induced rise in cellular calcium levels as one of the earliest biochemical readou...
Article
Ca2+ is a ubiquitous second messenger for cellular signalling in various stresses and developmental processes. Here, we summarize current developments in the roles of Ca2+ during plant immunity responses. We discuss the early perception events preceding and necessary for triggering cellular Ca2+ fluxes, the potential Ca2+-permeable channels, the de...
Article
Background: Plant perception of conserved microbe-derived or damage-derived molecules (so-called microbe- or damage-associated molecular patterns, MAMPs or DAMPs, respectively) triggers cellular signaling cascades to initiate counteracting defence responses. Using MAMP-induced rise in cellular calcium levels as one of the earliest biochemical reado...
Article
Full-text available
Calcium acts as a second messenger for signaling to a variety of stimuli including MAMPs (Microbe-Associated Molecular Patterns), such as flg22 and elf18 that are derived from bacterial flagellin and elongation factor Tu, respectively. Here, Arabidopsis thaliana mutants with changed calcium elevation (cce) in response to flg22 treatment were isolat...
Article
While diverse microbe- or damage-associated molecular patterns (MAMPs/DAMPs) typically trigger a common set of intracellular signalling events, comparative analysis between the MAMPs flg22 and elf18 revealed MAMP-specific differences in Ca(2+) signalling, defence gene expression and MAMP-mediated growth arrest in Arabidopsis thaliana. Such MAMP-spe...
Article
Calcium (Ca2+), as a second messenger, is crucial for signal transduction processes during many biotic interactions. We demonstrate that cellular [Ca2+] elevations are early events in the interaction between the plant growth-promoting fungus Piriformospora indica and Arabidopsis thaliana. A cell wall extract (CWE) from the fungus promotes the growt...
Article
The putative two-pore Ca(2+) channel TPC1 has been suggested to be involved in responses to abiotic and biotic stresses. We show that AtTPC1 co-localizes with the K(+)-selective channel AtTPK1 in the vacuolar membrane. Loss of AtTPC1 abolished Ca(2+)-activated slow vacuolar (SV) currents, which were increased in AtTPC1-over-expressing Arabidopsis c...
Article
Full-text available
Pathogen-associated molecular pattern (PAMP)-triggered immunity constitutes the primary plant immune response that has evolved to recognize invariant structures of microbial surfaces. Here we show that Gram-positive bacteria-derived peptidoglycan (PGN) constitutes a novel PAMP of immune responses in Arabidopsis thaliana. Treatment with PGN from Sta...
Article
Full-text available
Systemin is a wound-signaling peptide that mediates defenses of tomato plants against herbivorous insects. Perception of systemin by the membrane-bound receptor SR160 results in activation of MAPKs, synthesis of jasmonic acid (JA), and expression of defense genes. To test the function of MAPKs in the response to systemin, we used virus-induced gene...
Article
Full-text available
Genomic footprints across Rp, Zp, and oriLyt of Epstein-Barr virus (EBV) have been conducted in a panel of latently infected B-cell lines. Close protein-base contacts were found about 360 nucleotides upstream of the Zp initiation site. Gel shifts and transient transfection assays indicated that an Sp1-NF1 locus may serve as a repressive transcripti...

Projects

Project (1)
Project
Both, animals and plants sense invading pathogens through conserved microbe-associated molecular patterns (MAMPs), by specific host pattern-recognition receptors (PRRs) and trigger innate immune responses. Lipopolysaccharide (LPS) of gram-negative bacterial cell walls strongly activates extracellular and intracellular immune receptors in mammals. LPS triggers immune defences in plants, but the perception systems are not yet understood. We have recently shown that LPS is sensed as a MAMP in Arabidopsis thaliana and identified a key component of LPS signalling, the receptor-like kinase LORE (LipoOligosaccharide-specific Reduced Elicitation). As a highly restrictive barrier, LPS is also an important virulence factor. In my current projects, I want to characterize the properties of LPS as stimulator of plant immune responses and its role as virulence factor during plant infection by combining expertise in plant biochemistry, microbiology, structural biology as well as analytical chemistry.