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Publications - Stress and Develop Biology

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Publications

Guerra, T.; Schilling, S.; Hake, K.; Gorzolka, K.; Sylvester, F.-P.; Conrads, B.; Westermann, B.; Romeis, T. Calcium‐dependent protein kinase 5 links calcium‐signaling with N‐Hydroxy‐L‐pipecolic acid‐ and SARD1‐dependent immune memory in systemic acquired resistance New Phytol 225, 310-325, (2020) DOI: 10.1111/nph.16147

Systemic acquired resistance (SAR) prepares infected plants for faster and stronger defense activation upon subsequent attacks. SAR requires an information relay from primary infection to distal tissue and the initiation and maintenance of a self‐maintaining phytohormone salicylic acid (SA)‐defense loop.In spatial and temporal resolution, we show that calcium‐dependent protein kinase CPK5 contributes to immunity and SAR. In local basal resistance, CPK5 functions upstream of SA synthesis, perception, and signaling. In systemic tissue, CPK5 signaling leads to accumulation of SAR‐inducing metabolite N‐hydroxy‐L‐pipecolic acid (NHP) and SAR marker genes, including Systemic Acquired Resistance Deficient 1 (SARD1)Plants of increased CPK5, but not CPK6, signaling display an ‘enhanced SAR’ phenotype towards a secondary bacterial infection. In the sard1‐1 background, CPK5‐mediated basal resistance is still mounted, but NHP concentration is reduced and enhanced SAR is lost.The biochemical analysis estimated CPK5 half maximal kinase activity for calcium, K50 [Ca2+], to be c. 100 nM, close to the cytoplasmic resting level. This low threshold uniquely qualifies CPK5 to decode subtle changes in calcium, a prerequisite to signal relay and onset and maintenance of priming at later time points in distal tissue. Our data explain why CPK5 functions as a hub in basal and systemic plant immunity.
Publications

Wang, W.; Liu, N.; Gao, C.; Cai, H.; Romeis, T.; Tang, D. The Arabidopsis exocyst subunits EXO70B1 and EXO70B2 regulate FLS2 homeostasis at the plasma membrane New Phytol 227, 529-544, (2020) DOI: 10.1111/nph.16515

The plasma membrane (PM)‐localized receptor kinase FLAGELLIN SENSING 2 (FLS2) recognizes bacterial flagellin or its immunogenic epitope flg22, and initiates microbe‐associated molecular pattern‐triggered immunity, which inhibits infection by bacterial pathogens. The localization, abundance and activity of FLS2 are under dynamic control.Here, we demonstrate that Arabidopsis thaliana EXO70B1, a subunit of the exocyst complex, plays a critical role in FLS2 signaling that is independent of the truncated Toll/interleukin‐1 receptor‐nucleotide binding sequence protein TIR‐NBS2 (TN2). In the exo70B1‐3 mutant, the abundance of FLS2 protein at the PM is diminished, consistent with the impaired flg22 response of this mutant. EXO70B1‐GFP plants showed increased FLS2 accumulation at the PM and therefore enhanced FLS2 signaling.The EXO70B1‐mediated trafficking of FLS2 to the PM is partially independent of the PENETRATION 1 (PEN1)‐containing secretory pathway. In addition, EXO70B1 interacts with EXO70B2, a close homolog of EXO70B1, and both proteins associate with FLS2 and contribute to the accumulation of FLS2 at the PM.Taken together, our data suggest that the exocyst complex subunits EXO70B1 and EXO70B2 regulate the trafficking of FLS2 to the PM, which represents a new layer of regulation of FLS2 function in plant immunity.
Publications

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.
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

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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

Kumar, A.; Gopalswamy, M.; Wishart, C.; Henze, M.; Eschen-Lippold, L.; Donnelly, D.; Balbach, J. N-Terminal Phosphorylation of Parathyroid Hormone (PTH) Abolishes Its Receptor Activity ACS Chem Biol 9, 2465–2470, (2014) DOI: 10.1021/cb5004515

The parathyroid hormone (PTH) is an 84-residue peptide, which regulates the blood Ca2+ level via GPCR binding and subsequent activation of intracellular signaling cascades. PTH is posttranslationally phosphorylated in the parathyroid glands; however, the functional significance of this processes is not well characterized. In the present study, mass spectrometric analysis revealed three sites of phosphorylation, and NMR spectroscopy assigned Ser1, Ser3, and Ser17 as modified sites. These sites are located at the N-terminus of the hormone, which is important for receptor recognition and activation. NMR shows further that the three phosphate groups remotely disturb the α-helical propensity up to Ala36. An intracellular cAMP accumulation assay elucidated the biological significance of this phosphorylation because it ablated the PTH-mediated signaling. Our studies thus shed light on functional implications of phosphorylation at native PTH as an additional level of regulation 
Publications

Seybold, H.; Trempel, F.; Ranf, S.; Scheel, D.; Romeis, T.; Lee, J. Ca2+ signalling in plant immune response: from pattern recognition receptors to Ca2+ decoding mechanisms. New Phytol 204, 782–790, (2014) DOI: 10.1111/nph.13031

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 decoding of Ca2+ signals predominantly via Ca2+-dependent phosphorylation events and transcriptional reprogramming. To highlight the complexity of the cellular signal network, we briefly touch on the interplay between Ca2+-dependent signalling and selected major signalling mechanisms – with special emphasis on reactive oxygen species at local and systemic levels.
Books and chapters

Hummel, J.; Strehmel, N.; Bölling, C.; Schmidt, S.; Walther D.; Kopka, J. Mass spectral search and analysis using the Golm metabolome. (Weckwerth, W.; Kahl, G.). 321-343, (2013) ISBN: 978-3-527-32777-5 DOI: 10.1002/9783527669882.ch18

The novel “omics” technologies of the postgenomic era generate large multiplexed phenotyping datasets, which can only inadequately be published in the traditional journal and supplemental formats. For this reason, public databases have been developed that utilize the efficient communication of knowledge through the World Wide Web. This trend also applies to the metabolomics field, which is, after genomics, transcriptomics, and proteomics, the fourth major systems-level phenotyping platform. Each different analytical technology used in metabolomics studies requires specific reference data for metabolite identification and optimal data formats for reporting the complex metabolite profiling data features. Therefore, we envision that every technology platform or even each high-throughput metabolomic laboratory will establish dedicated databases, which will communicate between each other and will be integrated by meta-databases and web services. The Golm Metabolome Database (GMD) (http://gmd.mpimp-golm.mpg.de/) is a metabolomic database, maintained by the Max Planck Institute of Molecular Plant Physiology, that was initiated around a nucleus of reference data from gas chromatography–mass spectrometry metabolite profiling data and is now developing toward a general mass spectrometry-based repository of reference metabolite profiles for essential plant tissues and typical variations of growth conditions. This chapter describes the mass spectral searches and analyses currently supported by the GMD. We specifically address the searches for the different chemical entities within GMD, namely the metabolites, reference substances, and the chemically derivatized analytes. We report the diverse options for mass spectral analyses and highlight the decision tree-supported prediction of chemical substructures, a feature of GMD that currently appears to be a unique among the many tools for the analysis of gas chromatography–electron ionization mass spectra.
Publications

Eschen-Lippold, L.; Landgraf, R.; Smolka, U.; Schulze, S.; Heilmann, M.; Heilmann, I.; Hause, G.; Rosahl, S. Activation of defense against Phytophthora infestans in potato by down-regulation of syntaxin gene expression New Phytol 193, 985-996, (2012) DOI: 10.1111/j.1469-8137.2011.04024.x

The oomycete Phytophthora infestans is the causal agent of late blight, the most devastating disease of potato. The importance of vesicle fusion processes and callose deposition for defense of potato against Phytophthora infestans was analyzed.Transgenic plants were generated, which express RNA interference constructs targeted against plasma membrane‐localized SYNTAXIN‐RELATED 1 (StSYR1) and SOLUBLE N‐ETHYLMALEIMIDE‐SENSITIVE FACTOR ADAPTOR PROTEIN 33 (StSNAP33), the potato homologs of Arabidopsis AtSYP121 and AtSNAP33, respectively.Phenotypically, transgenic plants grew normally, but showed spontaneous necrosis and chlorosis formation at later stages. In response to infection with Phytophthora infestans, increased resistance of StSYR1‐RNAi plants, but not StSNAP33‐RNAi plants, was observed. This increased resistance correlated with the constitutive accumulation of salicylic acid and PR1 transcripts. Aberrant callose deposition in Phytophthora infestans‐infected StSYR1‐RNAi plants coincided with decreased papilla formation at penetration sites. Resistance against the necrotrophic fungus Botrytis cinerea was not significantly altered. Infiltration experiments with bacterial solutions of Agrobacterium tumefaciens and Escherichia coli revealed a hypersensitive phenotype of both types of RNAi lines.The enhanced defense status and the reduced growth of Phytophthora infestans on StSYR1‐RNAi plants suggest an involvement of syntaxins in secretory defense responses of potato and, in particular, in the formation of callose‐containing papillae.
Publications

Schulze, S.; Kay, S.; Büttner, D.; Egler, M.; Eschen-Lippold, L.; Hause, G.; Krüger, A.; Lee, J.; Müller, O.; Scheel, D.; Szczesny, R.; Thieme, F.; Bonas, U. Analysis of new type III effectors from Xanthomonas uncovers XopB and XopS as suppressors of plant immunity New Phytol 195, 894-911, (2012) DOI: 10.1111/j.1469-8137.2012.04210.x

The pathogenicity of the Gram-negative plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria (Xcv) is dependent on type III effectors (T3Es) that are injected into plant cells by a type III secretion system and interfere with cellular processes to the benefit of the pathogen. In this study, we analyzed eight T3Es from Xcv strain 85-10, six of which were newly identified effectors. Genetic studies and protoplast expression assays revealed that XopB and XopS contribute to disease symptoms and bacterial growth, and suppress pathogen-associated molecular pattern (PAMP)-triggered plant defense gene expression. In addition, XopB inhibits cell death reactions induced by different T3Es, thus suppressing defense responses related to both PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI). XopB localizes to the Golgi apparatus and cytoplasm of the plant cell and interferes with eukaryotic vesicle trafficking. Interestingly, a XopB point mutant derivative was defective in the suppression of ETI-related responses, but still interfered with vesicle trafficking and was only slightly affected with regard to the suppression of defense gene induction. This suggests that XopB-mediated suppression of PTI and ETI is dependent on different mechanisms that can be functionally separated.
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