Search

Your search keyword '"Löfke, Christian"' showing total 36 results
Start Over Author "Löfke, Christian"
36 results on '"Löfke, Christian"'

2. Author response: Endocytic trafficking promotes vacuolar enlargements for fast cell expansion rates in plants

Author

Dünser, Kai, primary, Schöller, Maria, additional, Rößling, Ann-Kathrin, additional, Löfke, Christian, additional, Xiao, Nannan, additional, Pařízková, Barbora, additional, Melnik, Stanislav, additional, Rodriguez-Franco, Marta, additional, Stöger, Eva, additional, Novák, Ondřej, additional, and Kleine-Vehn, Jürgen, additional

Published
2022
Full Text
View/download PDF

14. Alternative metabolic fates of phosphatidylinositol produced by PI-synthase isoforms in Arabidopsis thaliana

Author

Heilmann, Ingo, Löfke, Christian, Ischebeck, Till, König, Sabine, and Freitag, Sabine

Abstract

Phosphatidylinositol (PtdIns) is an important precursor for inositol-containing lipids, including polyphosphoinositides, which have multiple essential functions in eukaryotic cells. It was previously proposed that different regulatory functions of inositol-containing lipids may be performed by independent lipid-pools, however, it remains unclear how such subcellular pools are established and maintained. Here, a previously-uncharacterised Arabidopsis gene-product with similarity to the known Arabidopsis PI-synthase, PIS1, is shown to be an active enzyme, PIS2, capable of producing PtdIns in vitro. PIS1 and PIS2 diverged slightly in substrate preferences for cytidinediphospho-diacylglycerol species differing in fatty acid composition, PIS2 preferring unsaturated substrates in vitro. Transient expression of fluorescence-tagged PIS1 or PIS2 in onion epidermal cells indicates localisation of both enzymes in the endoplasmic reticulum and, possibly, Golgi, as was reported previously for fungal and mammalian homologues. Constitutive ectopic overexpression of PIS1 or PIS2 in Arabidopsis plants resulted in elevated levels of PtdIns in leaves. PIS2-overexpressors additionally exhibited significantly-elevated levels of PtdIns-4-phosphate and PtdIns-4,5-bisphosphate, whereas polyphosphoinositides were not elevated in plants overexpressing PIS1. In contrast, PIS1-overexpressors contained significantly-elevated levels of diacylglycerol and phosphatidylethanolamine, an effect not observed in plants overexpressing PIS2. Biochemical analysis of transgenic plants regarding fatty acids associated with relevant lipids indicates that lipids increasing with PIS1-overexpression were enriched in saturated or monounsaturated fatty acids, whereas lipids increasing with PIS2-overexpression, including polyphosphoinositides, contained more unsaturated fatty acids. The data indicate that PtdIns-populations originating from different PI-synthase isoforms may enter alternative routes of metabolic conversion, possibly based on specificity and immediate metabolic context of the biosynthetic enzymes. peerReviewed

Published
2010

19. Inositol trisphosphate-induced ca2+ signaling modulates auxin transport and pin polarity

Author

Zhang, Jing, Vanneste, Steffen, Brewer, Philip B., Michniewicz, Marta, Grones, Peter, Kleine-Vehn, Jürgen, Löfke, Christian, Teichmann, Thomas, Bielach, Agnieszka, Cannoot, Bernard, Hoyerová, Klára, Chen, Xu, Xue, Hong Wei, Benková, Eva, Zažímalová, Eva, Friml, Jiří, Zhang, Jing, Vanneste, Steffen, Brewer, Philip B., Michniewicz, Marta, Grones, Peter, Kleine-Vehn, Jürgen, Löfke, Christian, Teichmann, Thomas, Bielach, Agnieszka, Cannoot, Bernard, Hoyerová, Klára, Chen, Xu, Xue, Hong Wei, Benková, Eva, Zažímalová, Eva, and Friml, Jiří

Abstract

The phytohormone auxin is an important determinant of plant development. Directional auxin flow within tissues depends on polar localization of PIN auxin transporters. To explore regulation of PIN-mediated auxin transport, we screened for suppressors of PIN1 overexpression (supo) and identified an inositol polyphosphate 1-phosphatase mutant (supo1), with elevated inositol trisphosphate (InsP3) and cytosolic Ca2+ levels. Pharmacological and genetic increases in InsP3 or Ca2+ levels also suppressed the PIN1 gain-of-function phenotypes and caused defects in basal PIN localization, auxin transport and auxin-mediated development. In contrast, the reductions in InsP3 levels and Ca2+ signaling antagonized the effects of the supo1 mutation and disrupted preferentially apical PIN localization. InsP3 and Ca2+ are evolutionarily conserved second messengers involved in various cellular functions, particularly stress responses. Our findings implicate them as modifiers of cell polarity and polar auxin transport, and highlight a potential integration point through which Ca2+ signaling-related stimuli could influence auxin-mediated development.

Published
2011

21. Phosphatidylinositol 4,5-Bisphosphate Influences PIN Polarization by Controlling Clathrin-Mediated Membrane Trafficking inArabidopsis

Author

Ischebeck, Till, primary, Werner, Stephanie, additional, Krishnamoorthy, Praveen, additional, Lerche, Jennifer, additional, Meijón, Mónica, additional, Stenzel, Irene, additional, Löfke, Christian, additional, Wiessner, Theresa, additional, Im, Yang Ju, additional, Perera, Imara Y., additional, Iven, Tim, additional, Feussner, Ivo, additional, Busch, Wolfgang, additional, Boss, Wendy F., additional, Teichmann, Thomas, additional, Hause, Bettina, additional, Persson, Staffan, additional, and Heilmann, Ingo, additional

Published
2013
Full Text
View/download PDF

29. Transcription factor WRKY23 assists auxin distribution patterns during Arabidopsis root development through local control on flavonol biosynthesis

Author

Grunewald, Wim, primary, De Smet, Ive, additional, Lewis, Daniel R., additional, Löfke, Christian, additional, Jansen, Leentje, additional, Goeminne, Geert, additional, Vanden Bossche, Robin, additional, Karimi, Mansour, additional, De Rybel, Bert, additional, Vanholme, Bartel, additional, Teichmann, Thomas, additional, Boerjan, Wout, additional, Van Montagu, Marc C. E., additional, Gheysen, Godelieve, additional, Muday, Gloria K., additional, Friml, Jiří, additional, and Beeckman, Tom, additional

Published
2012
Full Text
View/download PDF

30. Inositol Trisphosphate-Induced Ca2+ Signaling Modulates Auxin Transport and PIN Polarity

Author

Zhang, Jing, primary, Vanneste, Steffen, additional, Brewer, Philip B., additional, Michniewicz, Marta, additional, Grones, Peter, additional, Kleine-Vehn, Jürgen, additional, Löfke, Christian, additional, Teichmann, Thomas, additional, Bielach, Agnieszka, additional, Cannoot, Bernard, additional, Hoyerová, Klára, additional, Chen, Xu, additional, Xue, Hong-Wei, additional, Benková, Eva, additional, Zažímalová, Eva, additional, and Friml, Jiří, additional

Published
2011
Full Text
View/download PDF

33. Actin-dependent vacuolar occupancy of the cell determines auxin-induced growth repression.

Author

Scheuring, David, Löfke, Christian, Krüger, Falco, Kittelmann, Maike, Eisa, Ahmed, Hughes, Louise, Smith, Richard S., Hawes, Chris, Schumacher, Karin, and Kleine-Vehn, Jürgen

Subjects
*AUXIN, *PLANT vacuoles, *PLANT cells & tissues, *CYTOSKELETON, *CYTOSOL
Abstract

The cytoskeleton is an early attribute of cellular life, and its main components are composed of conserved proteins. The actin cytoskeleton has a direct impact on the control of cell size in animal cells, but its mechanistic contribution to cellular growth in plants remains largely elusive. Here, we reveal a role of actin in regulating cell size in plants. The actin cytoskeleton shows proximity to vacuoles, and the phytohormone auxin not only controls the organization of actin filaments but also impacts vacuolar morphogenesis in an actindependent manner. Pharmacological and genetic interference with the actin-myosin system abolishes the effect of auxin on vacuoles and thus disrupts its negative influence on cellular growth. SEMbased 3D nanometer-resolution imaging of the vacuoles revealed that auxin controls the constriction and luminal size of the vacuole. We show that this actin-dependent mechanism controls the relative vacuolar occupancy of the cell, thus suggesting an unanticipated mechanism for cytosol homeostasis during cellular growth. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

34. SUPPRESSOR OF APICAL DOMINANCE1 of Sporisorium reilianum Modulates Inflorescence Branching Architecture in Maize and Arabidopsis.

Author

Ghareeb, Hassan, Drechsler, Frank, Löfke, Christian, Teichmann, Thomas, and Schirawski, Jan

Subjects
CORN diseases, ARABIDOPSIS thaliana, MYCOSES, IMMUNOMODULATORS, INFLORESCENCES, PLANT colonization
Abstract

The biotrophic fungus Sporisorium reilianum causes head smut of maize (Zea mays) after systemic plant colonization. Symptoms include the formation of multiple female inflorescences at subapical nodes of the stalk because of loss of apical dominance. By deletion analysis of cluster 19-1, the largest genomic divergence cluster in S. reilianum, we identified a secreted fungal effector responsible for S. reilianum-induced loss of apical dominance, which we named SUPPRESSOR OF APICAL DOMINANCE1 (SAD1). SAD1 transcript levels were highly up-regulated during biotrophic fungal growth in all infected plant tissues. SAD1- green fluorescent protein fusion proteins expressed by recombinant S. reilianum localized to the extracellular hyphal space. Transgenic Arabidopsis (Arabidopsis thaliana)-expressing green fluorescent protein-SAD1 displayed an increased number of secondary rosette-leaf branches. This suggests that SAD1 manipulates inflorescence branching architecture in maize and Arabidopsis through a conserved pathway. Using a yeast (Saccharomyces cerevisiae) two-hybrid library of S. reilianum-infected maize tissues, we identified potential plant interaction partners that had a predicted function in ubiquitination, signaling, and nuclear processes. Presence of SAD1 led to an increase of the transcript levels of the auxin transporter PIN-FORMED1 in the root and a reduction of the branching regulator TEOSINTE BRANCHED1 in the stalk. This indicates a role of SAD1 in regulation of apical dominance by modulation of branching through increasing transcript levels of the auxin transporter PIN1 and derepression of bud outgrowth. [ABSTRACT FROM AUTHOR]

Published
2015
Full Text
View/download PDF

35. Inositol Trisphosphate-Induced Ca2+ Signaling Modulates Auxin Transport and PIN Polarity

Author

Zhang, Jing, Vanneste, Steffen, Brewer, Philip B., Michniewicz, Marta, Grones, Peter, Kleine-Vehn, Jürgen, Löfke, Christian, Teichmann, Thomas, Bielach, Agnieszka, Cannoot, Bernard, Hoyerová, Klára, Chen, Xu, Xue, Hong-Wei, Benková, Eva, Zažímalová, Eva, and Friml, Jiří

Subjects
*INOSITOL phosphates, *CALCIUM, *PLANT hormones, *AUXIN, *PHARMACOLOGY, *CELL polarity
Abstract

Summary: The phytohormone auxin is an important determinant of plant development. Directional auxin flow within tissues depends on polar localization of PIN auxin transporters. To explore regulation of PIN-mediated auxin transport, we screened for suppressors of PIN1 overexpression (supo) and identified an inositol polyphosphate 1-phosphatase mutant (supo1), with elevated inositol trisphosphate (InsP3) and cytosolic Ca2+ levels. Pharmacological and genetic increases in InsP3 or Ca2+ levels also suppressed the PIN1 gain-of-function phenotypes and caused defects in basal PIN localization, auxin transport and auxin-mediated development. In contrast, the reductions in InsP3 levels and Ca2+ signaling antagonized the effects of the supo1 mutation and disrupted preferentially apical PIN localization. InsP3 and Ca2+ are evolutionarily conserved second messengers involved in various cellular functions, particularly stress responses. Our findings implicate them as modifiers of cell polarity and polar auxin transport, and highlight a potential integration point through which Ca2+ signaling-related stimuli could influence auxin-mediated development. [Copyright &y& Elsevier]

Published
2011
Full Text
View/download PDF

36. Vacuolar staining methods in plant cells.

Author

Scheuring D, Schöller M, Kleine-Vehn J, and Löfke C

Subjects
Arabidopsis chemistry, Cell Tracking methods, Fluoresceins chemistry, Pyridinium Compounds chemistry, Quaternary Ammonium Compounds chemistry, Arabidopsis cytology, Fluorescent Dyes chemistry, Plant Cells chemistry, Staining and Labeling methods, Vacuoles chemistry
Abstract

Commercially available fluorescent dyes enable the fast and specific visualization of plant vacuoles, allowing for investigation of membrane dynamics and vacuolar biogenesis in living cells. Here, we describe different approaches tinting the tonoplast or the vacuolar lumen with a range of dyes, and illustrate its utilization with established fluorescent-tagged marker lines.

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results