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Publications - Stress and Develop Biology

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Displaying results 1 to 10 of 14.

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.
Publications

Ranf, S.; Grimmer, J.; Pöschl, Y.; Pecher, P.; Chinchilla, D.; Scheel, D.; Lee, J.; Defense-Related Calcium Signaling Mutants Uncovered via a Quantitative High-Throughput Screen in Arabidopsis thaliana Mol. Plant 5, 115-130, (2012) DOI: 10.1093/mp/ssr064

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 isolated and characterized. Besides novel mutant alleles of the flg22 receptor, FLS2 (Flagellin-Sensitive 2), and the receptor-associated kinase, BAK1 (Brassinosteroid receptor 1-Associated Kinase 1), the new cce mutants can be categorized into two main groups—those with a reduced or an enhanced calcium elevation. Moreover, cce mutants from both groups show differential phenotypes to different sets of MAMPs. Thus, these mutants will facilitate the discovery of novel components in early MAMP signaling and bridge the gaps in current knowledge of calcium signaling during plant–microbe interactions. Last but not least, the screening method is optimized for speed (covering 384 plants in 3 or 10 h) and can be adapted to genetically dissect any other stimuli that induce a change in calcium levels.
Publications

Palm-Forster, M. A. T.; Eschen-Lippold, L.; Lee, J.; A mutagenesis-based screen to rapidly identify phosphorylation sites in mitogen-activated protein kinase substrates Anal. Biochem. 427, 127-129, (2012) DOI: 10.1016/j.ab.2012.05.015

Identification and characterization of protein phosphorylation sites often requires mass spectrometric analysis, which is not trivial or accessible to many laboratories. Here, a targeted strategy to mutagenize putative phosphorylation sites within mitogen-activated protein kinase (MAPK) substrates is described. This employs a combination of standard type II with type IIs restriction enzymes to rapidly create individual or multiple phosphorylation site mutant versions of kinase substrates with high efficiency, thereby reducing the cost for screening mutated clones.
Publications

Kirsten, S.; Navarro-Quezada, A.; Penselin, D.; Wenzel, C.; Matern, A.; Leitner, A.; Baum, T.; Seiffert, U.; Knogge, W.; Necrosis-Inducing Proteins of Rhynchosporium commune, Effectors in Quantitative Disease Resistance Mol. Plant Microbe Interact. 25, 1314-1325, (2012) DOI: 10.1094/MPMI-03-12-0065-R

The barley pathogen Rhynchosporium commune secretes necrosis-inducing proteins NIP1, NIP2, and NIP3. Expression analysis revealed that NIP1 transcripts appear to be present in fungal spores already, whereas NIP2 and NIP3 are synthesized after inoculation of host plants. To assess the contribution of the three effector proteins to disease development, deletion mutants were generated. The development of these fungal mutants on four barley cultivars was quantified in comparison with that of the parent wild-type strain and with two fungal strains failing to secrete an “active” NIP1 avirulence protein, using quantitative polymerase chain reaction as well as microscopic imaging after fungal green fluorescent protein tagging. The impact of the three deletions varied quantitatively depending on the host genotype, suggesting that the activities of the fungal effectors add up to produce stronger growth patterns and symptom development. Alternatively, recognition events of differing intensities may be converted into defense gene expression in a quantitative manner.
Publications

Eschen-Lippold, L.; Bethke, G.; Palm-Forster, M. A. T.; Pecher, P.; Bauer, N.; Glazebrook, J.; Scheel, D.; Lee, J.; MPK11—a fourth elicitor-responsive mitogen-activated protein kinase in Arabidopsis thaliana Plant Signal Behav. 7, 1203-1205, (2012) DOI: 10.4161/psb.21323

Recognition of pathogen attack or elicitation with pathogen-associated molecular patterns (PAMPs) leads to defense signaling that includes activation of the three mitogen-activated protein kinases (MPKs), MPK3, MPK4 and MPK6 in Arabidopsis. Recently, we demonstrated the activation of a fourth MPK, MPK11, after treatment with flg22, a 22 amino acid PAMP derived from bacterial flagellin. Here, we extended the study by examining elicitation with two other PAMPs, elf18 (derived from bacterial elongation factor EF-Tu) and ch8 (N-acetylchitooctaose derived from fungal chitin). Both PAMPs led to rapid MPK11 transcript accumulation and increased MPK11 kinase activity, suggesting that multiple PAMPs (or stresses) can activate MPK11. However, probably due to functional redundancies, bacteria-induced phytoalexin accumulation does not absolutely require MPK11.
Publications

Eschen-Lippold, L.; Rosahl, S.; Die Abwehr der Kartoffel gegen den Erreger der Kraut- und Knollenfäule Kartoffelbau 63, 38-39, (2012)

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Publications

Eschen-Lippold, L.; Lübken, T.; Smolka, U.; Rosahl, S.; Characterization of potato plants with reduced StSYR1 expression Plant Signal Behav. 7, 559-562, (2012) DOI: 10.4161/psb.19866

Vesicle fusion processes in plants are important for both development and stress responses. Transgenic potato plants with reduced expression of SYNTAXIN-RELATED1 (StSYR1), a gene encoding the potato homolog of Arabidopsis PENETRATION1 (AtPEN1), display spontaneous necrosis and chlorosis at later stages of development. In accordance with this developmental defect, tuber number, weight and overall yield are significantly reduced in StSYR1-RNAi lines. Enhanced resistance of StSYR1-RNAi plants to Phytophthora infestans, the causal agent of late blight disease of potato, correlates with enhanced levels of salicylic acid, whereas levels of 12-oxophytodienoic acid and jasmonic acid are unaltered. Cultured cells of StSYR1-RNAi lines secrete at least two compounds which are not detectable in the supernatant of control cells, suggesting an involvement of StSYR1 in secretion processes to the apoplast.
Publications

Caillaud, M.-. C.; Wirthmueller, L.; Fabro, G.; Piquerez, S. J. M.; Asai, S.; Ishaque, N.; Jones, J. D. G.; Mechanisms of Nuclear Suppression of Host Immunity by Effectors from the Arabidopsis Downy Mildew Pathogen Hyaloperonospora arabidopsidis (Hpa) Cold Spring Harb. Symp. Quant. Biol. 77, 285-293, (2012) DOI: 10.1101/sqb.2012.77.015115

Filamentous phytopathogens form sophisticated intracellular feeding structures called haustoria in plant cells. Pathogen effectors are likely to play a role in the establishment and maintenance of haustoria additional to their more characterized role of suppressing plant defense. Recent studies suggest that effectors may manipulate host transcription or other nuclear regulatory components for the benefit of pathogen development. However, the specific mechanisms by which these effectors promote susceptibility remain unclear. Of two recent screenings, we identified 15 nuclear-localized Hpa effectors (HaRxLs) that interact directly or indirectly with host nuclear components. When stably expressed in planta, nuclear HaRxLs cause diverse developmental phenotypes highlighting that nuclear effectors might interfere with fundamental plant regulatory mechanisms. Here, we report recent advances in understanding how a pathogen can manipulate nuclear processes in order to cause disease.
Publications

Brauch, S.; Henze, M.; Osswald, B.; Naumann, K.; Wessjohann, L. A.; van Berkel, S. S.; Westermann, B.; Fast and efficient MCR-based synthesis of clickable rhodamine tags for protein profiling Org. Biomol. Chem. 10, 958-965, (2012) DOI: 10.1039/C1OB06581E

Protein profiling probes are important tools for studying the composition of the proteome and as such have contributed greatly to the understanding of various complex biological processes in higher organisms. For this purpose the application of fluorescently labeled activity or affinity probes is highly desirable. Especially for in vivodetection of low abundant target proteins, otherwise difficult to analyse by standard blotting techniques, fluorescently labeled profiling probes are of high value. Here, a one-pot protocol for the synthesis of activated fluorescent labels (i.e.azide, alkynyl or NHS), based on the Ugi-4-component reaction (Ugi-4CR), is presented. As a result of the peptoidic structure formed, the fluorescent properties of the products are pH insensitive. Moreover, the applicability of these probes, as exemplified by the labeling of model protein BSA, will be discussed.
Publications

Bethke, G.; Pecher, P.; Eschen-Lippold, L.; Tsuda, K.; Katagiri, F.; Glazebrook, J.; Scheel, D.; Lee, J.; Activation of the Arabidopsis thaliana Mitogen-Activated Protein Kinase MPK11 by the Flagellin-Derived Elicitor Peptide, flg22 Mol. Plant Microbe Interact. 25, 471-480, (2012) DOI: 10.1094/MPMI-11-11-0281

Mitogen-activated protein kinases (MAPK) mediate cellular signal transduction during stress responses, as well as diverse growth and developmental processes in eukaryotes. Pathogen infection or treatments with conserved pathogen-associated molecular patterns (PAMPs) such as the bacterial flagellin-derived flg22 peptide are known to activate three Arabidopsis thaliana MAPK: MPK3, MPK4, and MPK6. Several stresses, including flg22 treatment, are known to increase MPK11 expression but activation of MPK11 has not been shown. Here, we show that MPK11 activity can, indeed, be increased through flg22 elicitation. A small-scale microarray for profiling defense-related genes revealed that cinnamyl alcohol dehyrogenase 5 requires MPK11 for full flg22-induced expression. An mpk11 mutant showed increased flg22-mediated growth inhibition but no altered susceptibility to Pseudomonas syringae, Botrytis cinerea, or Alternaria brassicicola. In mpk3, mpk6, or mpk4 backgrounds, MPK11 is required for embryo or seed development or general viability. Although this developmental deficiency in double mutants and the lack of or only subtle mpk11 phenotypes suggest functional MAPK redundancies, comparison with the paralogous MPK4 reveals distinct functions. Taken together, future investigations of MAPK roles in stress signaling should include MPK11 as a fourth PAMP-activated MAPK.
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