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Publikationen - Stress- und Entwicklungsbiologie

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Publikation

Nietzschmann, L.; Gorzolka, K.; Smolka, U.; Matern, A.; Eschen-Lippold, L.; Scheel, D.; Rosahl, S.; Early Pep-13-induced immune responses are SERK3A/B-dependent in potato Sci. Rep. 9, 18380, (2019) DOI: 10.1038/s41598-019-54944-y

Potato plants treated with the pathogen-associated molecular pattern Pep-13 mount salicylic acid- and jasmonic acid-dependent defense responses, leading to enhanced resistance against Phytophthora infestans, the causal agent of late blight disease. Recognition of Pep-13 is assumed to occur by binding to a yet unknown plasma membrane-localized receptor kinase. The potato genes annotated to encode the co-receptor BAK1, StSERK3A and StSERK3B, are activated in response to Pep-13 treatment. Transgenic RNAi-potato plants with reduced expression of both SERK3A and SERK3B were generated. In response to Pep-13 treatment, the formation of reactive oxygen species and MAP kinase activation, observed in wild type plants, is highly reduced in StSERK3A/B-RNAi plants, suggesting that StSERK3A/B are required for perception of Pep-13 in potato. In contrast, defense gene expression is induced by Pep-13 in both control and StSERK3A/B-depleted plants. Altered morphology of StSERK3A/B-RNAi plants correlates with major shifts in metabolism, as determined by untargeted metabolite profiling. Enhanced levels of hydroxycinnamic acid amides, typical phytoalexins of potato, in StSERK3A/B-RNAi plants are accompanied by significantly decreased levels of flavonoids and steroidal glycoalkaloids. Thus, altered metabolism in StSERK3A/B-RNAi plants correlates with the ability of StSERK3A/B-depleted plants to mount defense, despite highly decreased early immune responses.
Publikation

Menzel, W.; Stenzel, I.; Helbig, L.; Krishnamoorthy, P.; Neumann, S.; Eschen-Lippold, L.; Heilmann, M.; Lee, J.; Heilmann, I.; A PAMP‐triggered MAPK cascade inhibits phosphatidylinositol 4,5‐bisphosphate production by PIP5K6 in Arabidopsis thaliana New Phytol. 224, 833-847, (2019) DOI: 10.1111/nph.16069

The phosphoinositide kinase PIP5K6 has recently been identified as a target for the mitogen‐activated protein kinase (MAPK) MPK6. Phosphorylation of PIP5K6 inhibited the production of phosphatidylinositol 4,5‐bisphosphate (PtdIns(4,5)P2), impacting membrane trafficking and cell expansion in pollen tubes. Here, we analyzed whether MPK6 regulated PIP5K6 in vegetative Arabidopsis cells in response to the pathogen‐associated molecular pattern (PAMP) flg22.Promoter‐β‐glucuronidase analyses and quantitative real‐time reverse transcription polymerase chain reaction data show PIP5K6 expressed throughout Arabidopsis tissues. Upon flg22 treatment of transgenic protoplasts, the PIP5K6 protein was phosphorylated, and this modification was reduced for a PIP5K6 variant lacking MPK6‐targeted residues, or in protoplasts from mpk6 mutants.Upon flg22 treatment of Arabidopsis plants, phosphoinositide levels mildly decreased and a fluorescent reporter for PtdIns(4,5)P2 displayed reduced plasma membrane association, contrasting with phosphoinositide increases reported for abiotic stress responses. Flg22 treatment and chemical induction of the upstream MAPK kinase, MKK5, decreased phosphatidylinositol 4‐phosphate 5‐kinase activity in mesophyll protoplasts, indicating that the flg22‐activated MAPK cascade limited PtdIns(4,5)P2 production. PIP5K6 expression or PIP5K6 protein abundance changed only marginally upon flg22 treatment, consistent with post‐translational control of PIP5K6 activity. PtdIns(4,5)P2‐dependent endocytosis of FM 4‐64, PIN2 and the NADPH‐oxidase RbohD were reduced upon flg22 treatment or MKK5 induction. Reduced RbohD‐endocytosis was correlated with enhanced ROS production.We conclude that MPK6‐mediated phosphorylation of PIP5K6 limits the production of a functional PtdIns(4,5)P2 pool upon PAMP perception.
Publikation

Matern, A.; Böttcher, C.; Eschen-Lippold, L.; Westermann, B.; Smolka, U.; Döll, S.; Trempel, F.; Aryal, B.; Scheel, D.; Geisler, M.; Rosahl, S.; A substrate of the ABC transporter PEN3 stimulates bacterial flagellin (flg22)-induced callose deposition in Arabidopsis thaliana J. Biol. Chem. 294, 6857-6870, (2019) DOI: 10.1074/jbc.RA119.007676

Nonhost resistance of Arabidopsis thaliana against Phytophthora infestans, a filamentous eukaryotic microbe and the causal agent of potato late blight, is based on a multilayered defense system. Arabidopsis thaliana controls pathogen entry through the penetration-resistance genes PEN2 and PEN3, encoding an atypical myrosinase and an ABC transporter, respectively, required for synthesis and export of unknown indole compounds. To identify pathogen-elicited leaf surface metabolites and further unravel nonhost resistance in Arabidopsis, we performed untargeted metabolite profiling by incubating a P. infestans zoospore suspension on leaves of WT or pen3 mutant Arabidopsis plants. Among the plant-secreted metabolites, 4-methoxyindol-3-yl-methanol and S-(4-methoxy-indol-3-yl-methyl) cysteine were detected in spore suspensions recollected from WT plants, but at reduced levels from the pen3 mutant plants. In both whole-cell and microsome-based assays, 4-methoxyindol-3-yl-methanol was transported in a PEN3-dependent manner, suggesting that this compound is a PEN3 substrate. The syntheses of both compounds were dependent on functional PEN2 and phytochelatin synthase 1. None of these compounds inhibited mycelial growth of P. infestans in vitro. Of note, exogenous application of 4-methoxyindol-3-yl methanol slightly elevated cytosolic Ca2+ levels and enhanced callose deposition in hydathodes of seedlings treated with a bacterial pathogen-associated molecular pattern (PAMP), flagellin (flg22). Loss of flg22-induced callose deposition in leaves of pen3 seedlings was partially reverted by the addition of 4-methoxyindol-3-yl methanol. In conclusion, we have identified a specific indole compound that is a substrate for PEN3 and contributes to the plant defense response against microbial pathogens.
Publikation

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.
Publikation

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.
Publikation

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.
Publikation

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.
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.
Bücher und Buchkapitel

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.
Publikation

Strehmel, N.; Hoehenwarter, W.; Mönchgesang, S.; Majovsky, P.; Krüger, S.; Scheel, D.; Lee, J.; Stress-Related Mitogen-Activated Protein Kinases Stimulate the Accumulation of Small Molecules and Proteins in Arabidopsis thaliana Root Exudates Front. Plant Sci. 8, 1292, (2017) DOI: 10.3389/fpls.2017.01292

A delicate balance in cellular signaling is required for plants to respond to microorganisms or to changes in their environment. Mitogen-activated protein kinase (MAPK) cascades are one of the signaling modules that mediate transduction of extracellular microbial signals into appropriate cellular responses. Here, we employ a transgenic system that simulates activation of two pathogen/stress-responsive MAPKs to study release of metabolites and proteins into root exudates. The premise is based on our previous proteomics study that suggests upregulation of secretory processes in this transgenic system. An advantage of this experimental set-up is the direct focus on MAPK-regulated processes without the confounding complications of other signaling pathways activated by exposure to microbes or microbial molecules. Using non-targeted metabolomics and proteomics studies, we show that MAPK activation can indeed drive the appearance of dipeptides, defense-related metabolites and proteins in root apoplastic fluid. However, the relative levels of other compounds in the exudates were decreased. This points to a bidirectional control of metabolite and protein release into the apoplast. The putative roles for some of the identified apoplastic metabolites and proteins are discussed with respect to possible antimicrobial/defense or allelopathic properties. Overall, our findings demonstrate that sustained activation of MAPKs alters the composition of apoplastic root metabolites and proteins, presumably to influence the plant-microbe interactions in the rhizosphere. The reported metabolomics and proteomics data are available via Metabolights (Identifier: MTBLS441) and ProteomeXchange (Identifier: PXD006328), respectively.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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