Ralph Hückelhoven

Ralph Hückelhoven
Technische Universität München | TUM · Chair of Phytopathology

Full Professor

About

218
Publications
37,479
Reads
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9,744
Citations
Additional affiliations
September 2006 - present
Technische Universität München
Position
  • Head of Department
January 2000 - September 2006
Justus-Liebig-Universität Gießen
Position
  • Junior research group leader

Publications

Publications (218)
Article
In barley (Hordeum vulgare), signalling rat sarcoma homolog (RHO) of plants guanosine triphosphate hydrolases (ROP GTPases) support the penetration success of Blumeria graminis f. sp. hordei but little is known about ROP activation. Guanine nucleotide exchange factors (GEFs) facilitate the exchange of ROP‐bound GDP for GTP and thereby turn ROPs int...
Article
Plant pathogens such as Phytophthora infestans that caused the Irish Potato Famine continue to threaten local and global food security. Genetic and chemical plant protection measures are often overcome by adaptation of pathogen population structures. Therefore, there is a constant demand for new, consumer- and environment-friendly plant protection...
Article
Full-text available
Small RHO-type G-proteins act as signaling hubs and master regulators of polarity in eukaryotic cells. Their activity is tightly controlled, as defective RHO signaling leads to aberrant growth and developmental defects. Two major processes regulate G-protein activity: canonical shuttling between different nucleotide bound states and posttranslation...
Article
Full-text available
Plant immune responses must be tightly controlled for proper allocation of resources for growth and development. In plants, endogenous signaling peptides regulate developmental and growth-related processes. Recent research indicates that some of these peptides also have regulatory functions in the control of plant immune responses. This classifies...
Article
Full-text available
Early blight of potato is caused by the fungal pathogen Alternaria solani and is an increasing problem worldwide. The primary strategy to control the disease is applying fungicides such as succinate dehydrogenase inhibitors (SDHI). SDHI‐resistant strains, showing reduced sensitivity to treatments, appeared in Germany in 2013, shortly after the intr...
Article
Full-text available
Epidemiology of Fusarium Head Blight (FHB) of spring barley is relatively little understood. In a five-year study, we assessed quantitative resistance to FHB in an assortment of 17 spring barley genotypes in the field in southern Germany. To this end, we used soil and spray inoculation of plants with F. culmorum and F. avenaceum. This increased dis...
Preprint
Full-text available
Plants have evolved a vast variety of secondary metabolites to counteract biotic stress. Volatile organic compounds (VOCs) are carbon-based molecules induced by herbivore attack or pathogen infection. A mixture of plant VOCs is released for direct or indirect plant defense, plant-plant or plant-insect communication. Recent studies suggest that VOCs...
Data
This is raw data and supplements to: Eichmann et al. 2006. Macroarray expression analysis of barley susceptibility and nonhost resistance to Blumeria graminis J. Plant Physiol. Volume 163, Issue 6, Pages 657-670 https://doi.org/10.1016/j.jplph.2005.06.019
Preprint
Full-text available
In barley ( Hordeum vulgare ), the function of ROPs appears central to polar cell development and the interaction outcome with parasitic fungi but little is known about ROP activation. Guanine nucleotide exchange factors (GEFs) facilitate the exchange of GDP with GTP and thereby turn ROPs into a signalling-activated ROP-GTP state. Plants possess a...
Preprint
Full-text available
Early blight of potato is caused by the fungal pathogen Alternaria solani and is an increasing problem worldwide. The primary strategy to control the disease is applying fungicides such as succinate dehydrogenase inhibitors (SDHI). SDHI-resistant strains, showing reduced sensitivity to treatments, appeared in Germany in 2013, five years after intro...
Preprint
Full-text available
Natural plant populations are highly polymorphic and often show intraspecific quantitative, variation in resistance properties against pathogens. The activation of the underlying defence responses can depend on the perception of conserved pathogen-associated molecular patterns (PAMPs). To dissect and understand such variation, we evaluated the dive...
Article
α-Solanine and α-chaconine are the major glycoalkaloids (SGAs) in potatoes, but up to now the biosynthesis of these saponins is not fully understood. In planta13CO2 labeling experiments monitored by nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectrometry (HRMS) unraveled the SGA biosynthetic pathways from CO2 photosyntha...
Article
Full-text available
The wild tomato species Solanum chilense is divided into geographically and genetically distinct populations that show signs of defense gene selection and differential phenotypes when challenged with several phytopathogens, including the oomycete causal agent of late blight Phytophthora infestans. To better understand the phenotypic diversity of th...
Preprint
The wild tomato species Solanum chilense is divided in geographically and genetically distinct populations that show signs of defense gene selection and differential phenotypes when challenged with several phytopathogens, including the oomycete causal agent of late blight Phytophthora infestans. To better understand the phenotypic diversity of this...
Preprint
Endogenous plant signalling peptides regulate developmental and growth-related processes. Recent research indicates that some of these peptides are classified as phytocytokines as they have regulatory functions during plant immune responses. However, the mechanistic basis for phytocytokine-mediated immune modulation remains largely elusive. Here, w...
Data
Supplements to: Hoheneder et al. 2021: Ramularia leaf spot disease of barley is highly host genotype-dependent and suppressed by continuous drought stress in the field. J Plant Dis Prot
Article
Full-text available
Since the 1980s, Ramularia leaf spot (RLS) is an emerging barley disease worldwide. The control of RLS is increasingly aggravated by a recent decline in fungicide efficacy and a lack of RLS-resistant cultivars. Furthermore, climate change increases drought periods in Europe, enhances variable weather conditions, and thus will have an impact on seve...
Article
Attempted infections of plants with fungi result in diverse outcomes ranging from symptom-less resistance to severe disease and even death of infected plants. The deleterious effect on crop yield have led to intense focus on the cellular and molecular mechanisms that explain the difference between resistance and susceptibility. This research has un...
Article
Natural plant populations encounter strong pathogen pressure and defence-associated genes are known to be under selection dependent on the pressure by the pathogens. Here, we use populations of the wild tomato Solanum chilense to investigate natural resistance against Cladosporium fulvum , a well-known ascomycete pathogen of domesticated tomatoes....
Preprint
Full-text available
According to their lifestyle, plant pathogens are divided into biotrophic and necrotrophic organisms. While biotrophic pathogens establish a relationship with living host cells, necrotrophic pathogens rapidly kill host cells and feed on the cell debris. To this end, the necrotrophic ascomycete fungus Botrytis cinerea secretes large amounts of phyto...
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
Full-text available
Rho proteins of plants (ROPs) form a specific clade of Rho GTPases, which are involved in either plant immunity or susceptibility to diseases. They are intensively studied in grass host plants, in which ROPs are signaling hubs downstream of both cell surface immune receptor kinases and intracellular nucleotide-binding leucine-rich repeat receptors,...
Article
Rho of Plants (ROP) G-proteins are key components of cell polarization processes in plant development. The barley (Hordeum vulgare) ROP protein RACB, is a susceptibility factor in the interaction of barley with the barley powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh). RACB also drives polar cell development, and this function might be...
Preprint
Full-text available
Since the 1980s, Ramularia leaf spot (RLS) is an emerging barley disease world-wide. The control of RLS is increasingly aggravated by a recent decline in fungicide efficacy and a lack of RLS-resistant cultivars. Furthermore, climate change increases drought periods in Europe, enhances variable weather conditions and thus will have an impact on seve...
Preprint
Full-text available
Natural plant populations encounter strong pathogen pressure and defense-associated genes are known to be under different selection pressure dependent on the pressure by the pathogens. Here we use wild tomato Solanum chilense populations to investigate natural resistance against Cladosporium fulvum, a well-known pathogenic fungus of domesticated to...
Preprint
Full-text available
Small RHO-type G-proteins act as signaling hubs and master regulators of polarity in eukaryotic cells. Their activity is tightly controlled, as defective RHO signaling leads to aberrant growth and developmental defects. Two major pathways regulate G-protein activity: canonical switching of the nucleotide bound state and posttranslational modificati...
Article
Full-text available
The exchange of small RNAs (sRNAs) between hosts and pathogens can lead to gene silencing in the recipient organism, a mechanism termed cross-kingdom RNAi (ck-RNAi). While fungal sRNAs promoting virulence are established, the significance of ck-RNAi in distinct plant pathogens is not clear. Here, we describe that sRNAs of the pathogen Hyaloperonosp...
Article
Full-text available
The exchange of small RNAs (sRNAs) between hosts and pathogens can lead to gene silencing in the recipient organism, a mechanism termed cross-kingdom RNAi (ck-RNAi). While fungal sRNAs promoting virulence are established, the significance of ck-RNAi in distinct plant pathogens is not clear. Here, we describe that sRNAs of the pathogen Hyaloperonosp...
Article
Full-text available
The exchange of small RNAs (sRNAs) between hosts and pathogens can lead to gene silencing in the recipient organism, a mechanism termed cross-kingdom RNAi (ck-RNAi). While fungal sRNAs promoting virulence are established, the significance of ck-RNAi in distinct plant pathogens is not clear. Here, we describe that sRNAs of the pathogen Hyaloperonosp...
Article
Full-text available
Background: Small ROP (also called RAC) GTPases are key factors in polar cell development and in interaction with the environment. ROP-Interactive Partner (RIP) proteins are predicted scaffold or ROP-effector proteins, which function downstream of activated GTP-loaded ROP proteins in establishing membrane heterogeneity and cellular organization. G...
Preprint
Full-text available
Successful pathogens often benefit from certain cellular host processes. For the biotrophic ascomycete fungus Blumeria graminis f.sp. hordei (Bgh) it has been shown that barley RACB, a small monomeric G-protein (ROP, RHO of plants), is required for full susceptibility to fungal penetration. The susceptibility function of RACB probably lies in its r...
Article
Arabidopsis (Arabidopsis thaliana) efficiently synthesizes the antifungal phytoalexin camalexin without the apparent release of bioactive intermediates, such as indole-3-acetaldoxime, suggesting that the biosynthetic pathway of this compound is channeled by the formation of an enzyme complex. To identify such protein interactions, we used two indep...
Preprint
Full-text available
RHO of Plants (ROP) G-proteins are key components of cell polarization processes in plant development. The barley ( Hordeum vulgare ) ROP protein RACB, is a susceptibility factor in the interaction of barley with the barley powdery mildew fungus Blumeria graminis f.sp. hordei ( Bgh ). RACB also drives polar cell development, and this function might...
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
Ramularia leaf spot is becoming an ever-increasing problem in main barley-growing regions since the 1980s, causing up to 70% yield loss in extreme cases. Yet, the causal agent Ramularia collo-cygni remains poorly studied. The diversity of the pathogen in the field thus far remains unknown. Furthermore, it is unknown to what extent the pathogen has...
Article
Full-text available
The intracellular accommodation structures formed by plant cells to host arbuscular mycorrhiza fungi and biotrophic hyphal pathogens are cytologically similar. Therefore we investigated whether these interactions build on an overlapping genetic framework. In legumes, the malectin-like domain leucine-rich repeat receptor kinase SYMRK, the cation cha...
Preprint
Full-text available
Small ROP (also called RAC) GTPases are key factors in polar cell development and in interaction with the environment. ROP-Interactive Partner (RIP) proteins are predicted scaffold or ROP-effector proteins, which function downstream of activated GTP-loaded ROP proteins in establishing membrane heterogeneity and cellular organization. Grass ROP prot...
Data
Actin filaments in susceptible (MLO) and resistant barley (mlo5) during attack by Blumeria graminis f.sp. hordei. Actin was stained by Alexa Fluor® 488 -phalloidin and imaged by confocal laser microscopy. Microfilaments are shown in green (b,f,j), autofluorescence in red (c,g,k). Fungi were visualized by transmission imaging (e,i). (a-d) Pictures s...
Data
Actin filament arrays in long epidermal cells of barley (Ingrid-MLO) during penetration by Blumeria graminis f.sp. hordei. Microfilaments are visible in green, plant and fungal autofluorescence in orange-red. Fungi were also visualized by whole-leaf transmission imaging (a). (c) Higher magnification of b. (a-c) Pictures show an attacked long cell w...
Data
Subcellular actin filament rearrangement in barley epidermal cells during attack by Blumeria graminis f.sp. hordei. Microfilaments are shown in green, plant and fungal autofluorescence in orange-red (b,d). Fungi were visualized by whole-leaf transmission imaging (a,c). (a,b) Pictures show an attacked cell (arrow marks the site of attack) with actin...
Data
Actin filament arrays in epidermal cells of barley (Backcross Ingrid-mlo5) during defence against penetration by Blumeria graminis f.sp. hordei. Microfilaments are visible in green, plant and fungal autofluorescence in red. Fungi were also visualized by whole-leaf transmission imaging (a,e). (a-d) Pictures show an attacked cell with filamentous act...
Data
Subcellular actin filament rearrangement in barley (Ingrid-MLO) epidermal cells during attack by Blumeria graminis f.sp. hordei at 24 hai. Microfilaments are shown in green, plant and fungal autofluorescence in orange-red (b,d,f). Fungi were visualized by whole-leaf transmission imaging (a,c,e). (a,b) Pictures show an penetrated cell (arrow marks t...
Preprint
Full-text available
Fungal small RNAs (sRNAs) hijack the plant RNA silencing pathway to manipulate host gene expression, named cross-kingdom RNA interference (ckRNAi). It is currently unknown how conserved and significant ckRNAi is for microbial virulence. Here, we found for the first time that sRNAs of a pathogen representing the oomycete kingdom invade the host plan...
Article
The fungus Alternaria solani is the main pathogen causing early blight on potatoes (Solanum tuberosum L.). An increase in the development of resistance to the succinate dehydrogenase inhibitor (SDHI) boscalid, one of the main active ingredients for the control of early blight, has been reported. For this study, monitoring data from Germany were col...
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
A broad range of different Fusarium (F.) species is associated with Fusarium head blight (FHB) on barley and the corresponding negative effects in downstream processing of barley grain in food and feed production. Previous studies highlight the significance of the wheat-relevant and well-studied species F. graminearum as well as less prominent spec...
Article
Full-text available
Agricultural productivity depends on increasingly extreme weather phenomena, and the use of germplasm that has to be continuously improved by plant breeders to become tolerant to various biotic and abiotic stresses. Molecular plant biologists try to understand the mechanisms associated with stress responses and provide knowledge that could be used...
Article
Ramularia leaf spot has recently emerged as a major threat to barley production world-wide, causing 25% yield loss in many barley growing regions. Here, we provide a new reference genome of the causal agent, the Dothideomycete Ramularia collo-cygni. The assembly of 32 Mb consists of 78 scaffolds. We used RNA-seq to identify 11,622 genes of which 1,...
Article
Full-text available
Background: The large and highly repetitive genomes of the cultivated species Hordeum vulgare (barley), Triticum aestivum (wheat), and Secale cereale (rye) belonging to the Triticeae tribe of grasses appear to be particularly rich in gene-like sequences including partial duplicates. Most of them have been classified as putative pseudogenes. In thi...
Article
Full-text available
Despite a high abundance and diversity of natural plant pathogens, plant disease susceptibility is rare. In agriculture however, disease epidemics often occur when virulent pathogens successfully overcome immunity of a single genotype grown in monoculture. Disease epidemics are partially controlled by chemical and genetic plant protection, but path...
Article
Full-text available
Pathogens overcome plant immunity by the means of secreted effectors. Host effector targets often act in pathogen defense but might also support fungal accommodation or nutrition. The barley ROP GTPase HvRACB is involved in accommodation of fungal haustoria of the powdery mildew fungus Blumeria graminis f.sp. hordei (Bgh) in barley epidermal cells....
Preprint
Full-text available
A bstract The interfaces through which nutrients are transferred from plant cells to arbuscular mycorrhiza fungi and biotrophic hyphal pathogens are structurally similar. We report that in Arabidopsis thaliana , mutations in homologs of common symbiosis genes (CSGs) encoding homologs of the symbiosis receptor kinase SYMRK, the nucleoporins NUP133 a...
Preprint
Full-text available
Plant immunity is overcome by pathogens by the means of secreted effectors. Host effector targets might be proteins acting in pathogen defense or serve demands of the pathogen. The barley ROP GTPase HvRACB is involved in entry of the powdery mildew fungus Blumeria graminis f.sp. hordei (Bgh) into barley epidermal cells. We found that HvRACB interac...
Article
The role of reactive oxygen intermediate (ROI) accumulation in resistance and susceptibility of plants to parasitic fungi is still little understood. We examined the spatial and temporal occurrence of different ROIs in barley after inoculation with the biotrophic fungus Blumeria graminis f.sp. hordei (Bgh, barley powdery mildew fungus). Using histo...
Article
The plant primary energy metabolism is profoundly reorganized under biotic stress conditions and there is increasing evidence for a role of the fermentative pathway in biotic interactions. Previously we showed via transient gene silencing or overexpression a function of barley alcohol dehydrogenase 1 (HvADH-1) in the interaction of barley with the...
Preprint
Full-text available
Ramularia Leaf Spot (RLS) has emerged as a threat for barley production in many regions of the world. Late appearance of unspecific symptoms caused that Ramularia collo-cygni could only by molecular diagnostics be detected as the causal agent of RLS. Although recent research has shed more light on the biology and genomics of the pathogen, the cause...
Article
Full-text available
In plant-pathogen interactions, components of the plant ubiquitination machinery are preferred targets of pathogen-encoded effectors suppressing defense responses or co-opting host cellular functions for accommodation. Here, we employed transient and stable gene silencing- and over-expression systems in Hordeum vulgare (barley) to study the functio...