jump to searchjump to navigationjump to content

Publications - Stress and Develop Biology

Sort by: Year Type of publication

Displaying results 1 to 10 of 20.

Preprints

Teh, O.-K.; Lee, C.-W.; Ditengou, F. A.; Klecker, T.; Furlan, G.; Zietz, M.; Hause, G.; Eschen-Lippold, L.; Hoehenwarter, W.; Lee, J.; Ott, T.; Trujillo, M.; Phosphorylation of the exocyst subunit Exo70B2 contributes to the regulation of its function bioRxiv (2018) DOI: 10.1101/266171

The exocyst is a conserved hetero-octameric complex that mediates early tethering of post-Golgi vesicles during exocytosis. Its Exo70 subunit functions as a spatiotemporal regulator by mediating numerous interactions with proteins and lipids. However, a molecular understanding of the exocyst functions remains challenging. Exo70B2 localized to dynamic foci at the plasma membrane and transited through Brefeldin A (BFA)-sensitive compartments, indicating that it participates in conventional secretion. Conversely, treatment with the immunogenic peptide flg22 or the salicylic acid (SA) defence hormone analogue Benzothiadiazole (BTH), induced Exo70B2 transport into the vacuole where it colocalized with autophagic markers AUTOPHAGY-RELATED PROTEIN 8 (ATG8) and NEIGHBOR OF BRCA1 GENE 1 (NBR1). According with its role in immunity, we discovered that Exo70B2 interacts with and is phosphorylated by the MITOGEN-ACTIVATED PROTEIN KINASE 3 (MPK3). Mimicking phosphorylation inhibited Exo70B2 localization at sites of active secretion. By contrast, lines expressing phosphonull variants displayed higher Effector-Triggered Immunity and were hypersensitive to BTH, conditions known to induce the secretory pathway. Our results suggest a molecular mechanism by which phosphorylation of Exo70B2 regulates interaction with the plasma membrane, and couples the secretory pathway with cellular signalling.
Publications

Sopeña-Torres, S.; Jordá, L.; Sánchez-Rodríguez, C.; Miedes, E.; Escudero, V.; Swami, S.; López, G.; Piślewska-Bednarek, M.; Lassowskat, I.; Lee, J.; Gu, Y.; Haigis, S.; Alexander, D.; Pattathil, S.; Muñoz-Barrios, A.; Bednarek, P.; Somerville, S.; Schulze-Lefert, P.; Hahn, M. G.; Scheel, D.; Molina, A.; YODA MAP3K kinase regulates plant immune responses conferring broad-spectrum disease resistance New Phytol. 218, 661-680, (2018) DOI: 10.1111/nph.15007

Mitogen‐activated protein kinases (MAPKs) cascades play essential roles in plants by transducing developmental cues and environmental signals into cellular responses. Among the latter are microbe‐associated molecular patterns perceived by pattern recognition receptors (PRRs), which trigger immunity.We found that YODA (YDA) – a MAPK kinase kinase regulating several Arabidopsis developmental processes, like stomatal patterning – also modulates immune responses. Resistance to pathogens is compromised in yda alleles, whereas plants expressing the constitutively active YDA (CA‐YDA) protein show broad‐spectrum resistance to fungi, bacteria, and oomycetes with different colonization modes. YDA functions in the same pathway as ERECTA (ER) Receptor‐Like Kinase, regulating both immunity and stomatal patterning.ER‐YDA‐mediated immune responses act in parallel to canonical disease resistance pathways regulated by phytohormones and PRRs. CA‐YDA plants exhibit altered cell‐wall integrity and constitutively express defense‐associated genes, including some encoding putative small secreted peptides and PRRs whose impairment resulted in enhanced susceptibility phenotypes. CA‐YDA plants show strong reprogramming of their phosphoproteome, which contains protein targets distinct from described MAPKs substrates.Our results suggest that, in addition to stomata development, the ER‐YDA pathway regulates an immune surveillance system conferring broad‐spectrum disease resistance that is distinct from the canonical pathways mediated by described PRRs and defense Hormones.
Publications

Zembek, P.; Danilecka, A.; Hoser, R.; Eschen-Lippold, L.; Benicka, M.; Grech-Baran, M.; Rymaszewski, W.; Barymow-Filoniuk, I.; Morgiewicz, K.; Kwiatkowski, J.; Piechocki, M.; Poznanski, J.; Lee, J.; Hennig, J.; Krzymowska, M.; Two Strategies of Pseudomonas syringae to Avoid Recognition of the HopQ1 Effector in Nicotiana Species Front. Plant Sci. 9, 978, (2018) DOI: 10.3389/fpls.2018.00978

Pseudomonas syringae employs a battery of type three secretion effectors to subvert plant immune responses. In turn, plants have developed receptors that recognize some of the bacterial effectors. Two strain-specific HopQ1 effector variants (for Hrp outer protein Q) from the pathovars phaseolicola 1448A (Pph) and tomato DC3000 (Pto) showed considerable differences in their ability to evoke disease symptoms in Nicotiana benthamiana. Surprisingly, the variants differ by only six amino acids located mostly in the N-terminal disordered region of HopQ1. We found that the presence of serine 87 and leucine 91 renders PtoHopQ1 susceptible to N-terminal processing by plant proteases. Substitutions at these two positions did not strongly affect PtoHopQ1 virulence properties in a susceptible host but they reduced bacterial growth and accelerated onset of cell death in a resistant host, suggesting that N-terminal mutations rendered PtoHopQ1 susceptible to processing in planta and, thus, represent a mechanism of recognition avoidance. Furthermore, we found that co-expression of HopR1, another effector encoded within the same gene cluster masks HopQ1 recognition in a strain-dependent manner. Together, these data suggest that HopQ1 is under high host-pathogen co-evolutionary selection pressure and P. syringae may have evolved differential effector processing or masking as two independent strategies to evade HopQ1 recognition, thus revealing another level of complexity in plant – microbe interactions.
Publications

Wirthmueller, L.; Asai, S.; Rallapalli, G.; Sklenar, J.; Fabro, G.; Kim, D. S.; Lintermann, R.; Jaspers, P.; Wrzaczek, M.; Kangasjärvi, J.; MacLean, D.; Menke, F. L. H.; Banfield, M. J.; Jones, J. D. G.; Arabidopsis downy mildew effector HaRxL106 suppresses plant immunity by binding to RADICAL-INDUCED CELL DEATH1 New Phytol. 220, 232-248, (2018) DOI: 10.1111/nph.15277

The oomycete pathogen Hyaloperonospora arabidopsidis (Hpa) causes downy mildew disease on Arabidopsis. To colonize its host, Hpa translocates effector proteins that suppress plant immunity into infected host cells. Here, we investigate the relevance of the interaction between one of these effectors, HaRxL106, and Arabidopsis RADICAL‐INDUCED CELL DEATH1 (RCD1).We use pathogen infection assays as well as molecular and biochemical analyses to test the hypothesis that HaRxL106 manipulates RCD1 to attenuate transcriptional activation of defense genes.We report that HaRxL106 suppresses transcriptional activation of salicylic acid (SA)‐induced defense genes and alters plant growth responses to light. HaRxL106‐mediated suppression of immunity is abolished in RCD1 loss‐of‐function mutants. We report that RCD1‐type proteins are phosphorylated, and we identified Mut9‐like kinases (MLKs), which function as phosphoregulatory nodes at the level of photoreceptors, as RCD1‐interacting proteins. An mlk1,3,4 triple mutant exhibits stronger SA‐induced defense marker gene expression compared with wild‐type plants, suggesting that MLKs also affect transcriptional regulation of SA signaling.Based on the combined evidence, we hypothesize that nuclear RCD1/MLK complexes act as signaling nodes that integrate information from environmental cues and pathogen sensors, and that the Arabidopsis downy mildew pathogen targets RCD1 to prevent activation of plant immunity.
Publications

Chen, C.; Masi, R. D.; Lintermann, R.; Wirthmueller, L.; Nuclear Import of Arabidopsis Poly(ADP-Ribose) Polymerase 2 Is Mediated by Importin-α and a Nuclear Localization Sequence Located Between the Predicted SAP Domains Front. Plant Sci. 9, 1581, (2018) DOI: 10.3389/fpls.2018.01581

Proteins of the Poly(ADP-Ribose) Polymerase (PARP) family modify target proteins by covalent attachment of ADP-ribose moieties onto amino acid side chains. In Arabidopsis, PARP proteins contribute to repair of DNA lesions and modulate plant responses to various abiotic and biotic stressors. Arabidopsis PARP1 and PARP2 are nuclear proteins and given that their molecular weights exceed the diffusion limit of nuclear pore complexes, an active import mechanism into the nucleus is likely. Here we use confocal microscopy of fluorescent protein-tagged Arabidopsis PARP2 and PARP2 deletion constructs in combination with site-directed mutagenesis to identify a nuclear localization sequence in PARP2 that is required for nuclear import. We report that in co-immunoprecipitation assays PARP2 interacts with several isoforms of the importin-α group of nuclear transport adapters and that PARP2 binding to IMPORTIN-α2 is mediated by the identified nuclear localization sequence. Our results demonstrate that PARP2 is a cargo protein of the canonical importin-α/β nuclear import pathway.
Books and chapters

Knogge, W.; Diseases affecting barley: scald (Oliver, R., ed.). Burleigh Dodds Series in Agricultural Science 183-215, (2018) DOI: 10.19103/as.2018.0039.10

Scald (leaf blotch), caused by the hemibiotrophic pathogen Rhynchosporium commune, is one of the major diseases of barley worldwide. Typical disease symptoms consist of necrotic areas on the leaf blades. Yield losses are manifested as reduced kernel quality, size and number per ear. This chapter reviews the origins, epidemiology and other characteristic features of scald, and considers the agricultural consequences of the pathogen’s biology. It then considers resistance breeding programmes in which more than a dozen major resistance genes as well as quantitative trait loci have been identified, and discusses strategies to minimize the damage caused by the disease comprising agricultural practices and different fungicides.
Publications

Ranf, S.; Scheel, D.; Lee, J.; Challenges in the identification of microbe-associated molecular patterns in plant and animal innate immunity: a case study with bacterial lipopolysaccharide Mol. Plant Pathol. 17, 1165-1169, (2016) DOI: 10.1111/mpp.12452

Immunity against pathogen infection depends on a host's ability to sense invading pathogens and to rapidly trigger defence reactions that block pathogen proliferation. Both plants and animals detect conserved structural motifs of microbe‐specific compounds, so‐called microbe‐associated molecular patterns (MAMPs), through germline‐encoded immune sensors, which are accordingly termed pattern recognition receptors (PRRs) (Akira et al., 2006; Boller and Felix, 2009). Activated PRRs initiate signal transduction and trigger innate immune responses. MAMPs are generally derived from elements essential for microbial fitness and are conserved across species, thus enabling the host to detect a range of potential pathogens. In mammals, innate immune sensing of MAMPs is not only crucial for basal immune responses but is also tightly connected with and required for a subsequent adaptive, antibody‐mediated immunity (Akira et al., 2006; Janeway and Medzhitov, 2002). Plants, lacking an adaptive immune system, have apparently evolved a greater capacity to detect a broader repertoire of MAMPs. Different plant species possess distinct sets of highly specific PRRs, but the downstream signalling pathways are rather conserved and converge on common signalling steps. This allows the transfer of PRRs, even to different plant families, whilst maintaining their functionality and specificity (Zipfel, 2014). This also enables researchers to use well‐studied, genetically amenable model systems for the identification of MAMPs and their respective PRRs. Several examples of interfamily PRR transfer have demonstrated that the introduction of novel PRRs into plant species can confer relevant levels of resistance to otherwise susceptible plants (e.g. Afroz et al., 2011; Hao et al., 2015; Lacombe et al., 2010; Mendes et al., 2010; Schoonbeek et al., 2015; Tripathi et al., 2014). Hence, MAMP sensing by PRRs has great potential for the engineering of disease resistance in crop plants. In recent years, it has therefore become a major task to identify and isolate MAMPs from a range of microorganisms, and their respective PRRs, to study their role in innate immunity and their application potential.
Publications

Penselin, D.; Münsterkötter, M.; Kirsten, S.; Felder, M.; Taudien, S.; Platzer, M.; Ashelford, K.; Paskiewicz, K. H.; Harrison, R. J.; Hughes, D. J.; Wolf, T.; Shelest, E.; Graap, J.; Hoffmann, J.; Wenzel, C.; Wöltje, N.; King, K. M.; Fitt, B. D. L.; Güldener, U.; Avrova, A.; Knogge, W.; Comparative genomics to explore phylogenetic relationship, cryptic sexual potential and host specificity of Rhynchosporium species on grasses BMC Genomics 17, 953, (2016) DOI: 10.1186/s12864-016-3299-5

BackgroundThe Rhynchosporium species complex consists of hemibiotrophic fungal pathogens specialized to different sweet grass species including the cereal crops barley and rye. A sexual stage has not been described, but several lines of evidence suggest the occurrence of sexual reproduction. Therefore, a comparative genomics approach was carried out to disclose the evolutionary relationship of the species and to identify genes demonstrating the potential for a sexual cycle. Furthermore, due to the evolutionary very young age of the five species currently known, this genus appears to be well-suited to address the question at the molecular level of how pathogenic fungi adapt to their hosts.ResultsThe genomes of the different Rhynchosporium species were sequenced, assembled and annotated using ab initio gene predictors trained on several fungal genomes as well as on Rhynchosporium expressed sequence tags. Structures of the rDNA regions and genome-wide single nucleotide polymorphisms provided a hypothesis for intra-genus evolution. Homology screening detected core meiotic genes along with most genes crucial for sexual recombination in ascomycete fungi. In addition, a large number of cell wall-degrading enzymes that is characteristic for hemibiotrophic and necrotrophic fungi infecting monocotyledonous hosts were found. Furthermore, the Rhynchosporium genomes carry a repertoire of genes coding for polyketide synthases and non-ribosomal peptide synthetases. Several of these genes are missing from the genome of the closest sequenced relative, the poplar pathogen Marssonina brunnea, and are possibly involved in adaptation to the grass hosts. Most importantly, six species-specific genes coding for protein effectors were identified in R. commune. Their deletion yielded mutants that grew more vigorously in planta than the wild type.ConclusionBoth cryptic sexuality and secondary metabolites may have contributed to host adaptation. Most importantly, however, the growth-retarding activity of the species-specific effectors suggests that host adaptation of R. commune aims at extending the biotrophic stage at the expense of the necrotrophic stage of pathogenesis. Like other apoplastic fungi Rhynchosporium colonizes the intercellular matrix of host leaves relatively slowly without causing symptoms, reminiscent of the development of endophytic fungi. Rhynchosporium may therefore become an object for studying the mutualism-parasitism transition.
Publications

Mönchgesang, S.; Strehmel, N.; Trutschel, D.; Westphal, L.; Neumann, S.; Scheel, D.; Plant-to-Plant Variability in Root Metabolite Profiles of 19 Arabidopsis thaliana Accessions Is Substance-Class-Dependent Int. J. Mol. Sci. 17, 1565, (2016) DOI: 10.3390/ijms17091565

Natural variation of secondary metabolism between different accessions of Arabidopsis thaliana (A. thaliana) has been studied extensively. In this study, we extended the natural variation approach by including biological variability (plant-to-plant variability) and analysed root metabolic patterns as well as their variability between plants and naturally occurring accessions. To screen 19 accessions of A. thaliana, comprehensive non-targeted metabolite profiling of single plant root extracts was performed using ultra performance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC/ESI-QTOF-MS) and gas chromatography/electron ionization quadrupole mass spectrometry (GC/EI-QMS). Linear mixed models were applied to dissect the total observed variance. All metabolic profiles pointed towards a larger plant-to-plant variability than natural variation between accessions and variance of experimental batches. Ratios of plant-to-plant to total variability were high and distinct for certain secondary metabolites. None of the investigated accessions displayed a specifically high or low biological variability for these substance classes. This study provides recommendations for future natural variation analyses of glucosinolates, flavonoids, and phenylpropanoids and also reference data for additional substance classes.
Publications

Mönchgesang, S.; Strehmel, N.; Schmidt, S.; Westphal, L.; Taruttis, F.; Müller, E.; Herklotz, S.; Neumann, S.; Scheel, D.; Natural variation of root exudates in Arabidopsis thaliana-linking metabolomic and genomic data Sci. Rep. 6, 29033, (2016) DOI: 10.1038/srep29033

Many metabolomics studies focus on aboveground parts of the plant, while metabolism within roots and the chemical composition of the rhizosphere, as influenced by exudation, are not deeply investigated. In this study, we analysed exudate metabolic patterns of Arabidopsis thaliana and their variation in genetically diverse accessions. For this project, we used the 19 parental accessions of the Arabidopsis MAGIC collection. Plants were grown in a hydroponic system, their exudates were harvested before bolting and subjected to UPLC/ESI-QTOF-MS analysis. Metabolite profiles were analysed together with the genome sequence information. Our study uncovered distinct metabolite profiles for root exudates of the 19 accessions. Hierarchical clustering revealed similarities in the exudate metabolite profiles, which were partly reflected by the genetic distances. An association of metabolite absence with nonsense mutations was detected for the biosynthetic pathways of an indolic glucosinolate hydrolysis product, a hydroxycinnamic acid amine and a flavonoid triglycoside. Consequently, a direct link between metabolic phenotype and genotype was detected without using segregating populations. Moreover, genomics can help to identify biosynthetic enzymes in metabolomics experiments. Our study elucidates the chemical composition of the rhizosphere and its natural variation in A. thaliana, which is important for the attraction and shaping of microbial communities.
IPB Mainnav Search