@Article{IPB-1453, author = {Kopischke, M. and Westphal, L. and Schneeberger, K. and Clark, R. and Ossowski, S. and Wewer, V. and Fuchs, R. and Landtag, J. and Hause, G. and Dörmann, P. and Lipka, V. and Weigel, D. and Schulze-Lefert, P. and Scheel, D. and Rosahl, S.}, title = {{Impaired sterol ester synthesis alters the response of \textit{Arabidopsis thaliana} to \textit{Phytophthora infestans}.}}, year = {2013}, pages = {456-468}, journal = {Plant J}, doi = {10.1111/tpj.12046}, url = {http://onlinelibrary.wiley.com/doi/10.1111/tpj.12046/full}, volume = {73}, abstract = {Non-host resistance of Arabidopsis thaliana against Phytophthora infestans, the causal agent of late blight disease of potato, depends on efficient extracellular pre- and post-invasive resistance responses. Pre-invasive resistance against P. infestans requires the myrosinase PEN2. To identify additional genes involved in non-host resistance to P. infestans, a genetic screen was performed by re-mutagenesis of pen2 plants. Fourteen independent mutants were isolated that displayed an enhanced response to Phytophthora (erp) phenotype. Upon inoculation with P. infestans, two mutants, pen2-1 erp1-3 and pen2-1 erp1-4, showed an enhanced rate of mesophyll cell death and produced excessive callose deposits in the mesophyll cell layer. ERP1 encodes a phospholipid:sterol acyltransferase (PSAT1) that catalyzes the formation of sterol esters. Consistent with this, the tested T-DNA insertion lines of PSAT1 are phenocopies of erp1 plants. Sterol ester levels are highly reduced in all erp1/psat1 mutants, whereas sterol glycoside levels are increased twofold. Excessive callose deposition occurred independently of PMR4/GSL5 activity, a known pathogen-inducible callose synthase. A similar formation of aberrant callose deposits was triggered by the inoculation of erp1 psat1 plants with powdery mildew. These results suggest a role for sterol conjugates in cell non-autonomous defense responses against invasive filamentous pathogens.} } @Article{IPB-1378, author = {Goetz, S. and Hellwege, A. and Stenzel, I. and Kutter, C. and Hauptmann, V. and Forner, S. and Mc Caig, B. and Hause, G. and Miersch, O. and Wasternack, C. and Hause, B.}, title = {{Role of cis-12-oxo-phytodienoic acid in tomato embryo development.}}, year = {2012}, pages = {1715-1727}, journal = {Plant Physiol}, url = {http://www.plantphysiol.org/content/158/4/1715.abstract?sid=15b792ec-f1c9-4754-9157-00e7f5042900}, volume = {158 (4)}, abstract = { Oxylipins including jasmonates are signaling compounds in plant growth, development, and responses to biotic and abiotic stresses. In Arabidopsis (Arabidopsis thaliana) most mutants affected in jasmonic acid (JA) biosynthesis and signaling are male sterile, whereas the JA-insensitive tomato (Solanum lycopersicum) mutant jai1 is female sterile. The diminished seed formation in jai1 together with the ovule-specific accumulation of the JA biosynthesis enzyme allene oxide cyclase (AOC), which correlates with elevated levels of JAs, suggest a role of oxylipins in tomato flower/seed development. Here, we show that 35S::SlAOC-RNAi lines with strongly reduced AOC in ovules exhibited reduced seed set similarly to the jai1 plants. Investigation of embryo development of wild-type tomato plants showed preferential occurrence of AOC promoter activity and AOC protein accumulation in the developing seed coat and the embryo, whereas 12-oxo-phytodienoic acid (OPDA) was the dominant oxylipin occurring nearly exclusively in the seed coat tissues. The OPDA- and JA-deficient mutant spr2 was delayed in embryo development and showed an increased programmed cell death in the developing seed coat and endosperm. In contrast, the mutant acx1a, which accumulates preferentially OPDA and residual amount of JA, developed embryos similar to the wild type, suggesting a role of OPDA in embryo development. Activity of the residual amount of JA in the acx1a mutant is highly improbable since the known reproductive phenotype of the JA-insensitive mutant jai1 could be rescued by wound-induced formation of OPDA. These data suggest a role of OPDA or an OPDA-related compound for proper embryo development possibly by regulating carbohydrate supply and detoxification.} } @Article{IPB-1437, author = {Stenzel, I. and Otto, M. and Delker, C. and Kirmse, N. and Schmidt, D. and Miersch, O. and Hause, B. and Wasternack, C.}, title = {{ALLENE OXIDE CYCLASE (AOC) gene family members of Arabidopsis thaliana: tissue- and organ-specific promoter activities and in vivo heteromerization*}}, year = {2012}, pages = {6125-6138}, journal = {J Exp Bot.}, volume = {63}, abstract = { Jasmonates are important signals in plant stress responses and plant development. An essential step in the biosynthesis of jasmonic acid (JA) is catalysed by ALLENE OXIDE CYCLASE (AOC) which establishes the naturally occurring enantiomeric structure of jasmonates. In Arabidopsis thaliana, four genes encode four functional AOC polypeptides (AOC1, AOC2, AOC3, and AOC4) raising the question of functional redundancy or diversification. Analysis of transcript accumulation revealed an organ-specific expression pattern, whereas detailed inspection of transgenic lines expressing the GUS reporter gene under the control of individual AOC promoters showed partially redundant promoter activities during development: (i) In fully developed leaves, promoter activities of AOC1, AOC2, and AOC3 appeared throughout all leaf tissue, but AOC4 promoter activity was vascular bundle-specific; (ii) only AOC3 and AOC4 showed promoter activities in roots; and (iii) partially specific promoter activities were found for AOC1 and AOC4 in flower development. In situ hybridization of flower stalks confirmed the GUS activity data. Characterization of single and double AOC loss-of-function mutants further corroborates the hypothesis of functional redundancies among individual AOCs due to a lack of phenotypes indicative of JA deficiency (e.g. male sterility). To elucidate whether redundant AOC expression might contribute to regulation on AOC activity level, protein interaction studies using bimolecular fluorescence complementation (BiFC) were performed and showed that all AOCs can interact among each other. The data suggest a putative regulatory mechanism of temporal and spatial fine-tuning in JA formation by differential expression and via possible heteromerization of the four AOCs.} } @Article{IPB-1392, author = {Vadassery, J. and Reichelt, M. and Hause, B. and Gershenzon, J. and Boland, W. and Mithöfer, A.}, title = {{CML42-mediated calcium signaling co-ordinates responses to Spodoptera herbivory and abiotic stresses in Arabidopsis.}}, year = {2012}, pages = {1159-1175}, journal = {Plant Physiol}, volume = {159}, } @Article{IPB-1448, author = {Stegmann, M. and Anderson, R.G. and Ichimura, K. and Pecenkova, T. and Reuter ,P. and Arsky, V. and McDowell, J.M. and Shirasu, K. and Trujillo, M.}, title = {{The Ubiquitin Ligase PUB22 Targets a Subunit of the Exocyst Complex Required for PAMP-Triggered Responses in \textit{Arabidopsis}}}, year = {2012}, pages = {1-14}, journal = {Plant Cell}, url = {http://www.plantcell.org/cgi/doi/10.1105/tpc.112.104463}, abstract = { Plant pathogens are perceived by pattern recognition receptors, which are activated upon binding to pathogen-associated molecular patterns (PAMPs). Ubiquitination and vesicle trafficking have been linked to the regulation of immune signaling. However, little information exists about components of vesicle trafficking involved in immune signaling and the mechanisms that regulate them. In this study, we identified Arabidopsis thaliana Exo70B2, a subunit of the exocyst complex that mediates vesicle tethering during exocytosis, as a target of the plant U-boxtype ubiquitin ligase 22 (PUB22), which acts in concert with PUB23 and PUB24 as a negative regulator of PAMP-triggered responses. We show that Exo70B2 is required for both immediate and later responses triggered by all tested PAMPs, suggestive of a role in signaling. Exo70B2 is also necessary for the immune response against different pathogens. Our data demonstrate that PUB22 mediates the ubiquitination and degradation of Exo70B2 via the 26S Proteasome. Furthermore, degradation is regulated by the autocatalytic turnover of PUB22, which is stabilized upon PAMP perception. We therefore propose a mechanism by which PUB22-mediated degradation of Exo70B2 contributes to the attenuation of PAMP-induced signaling.} } @Article{IPB-1370, author = {Fellenberg, C. and van Ohlen, M. and Handrick, V. and Vogt, T.}, title = {{The role of CCoAOMT and COMT in Arabidopsis anthers.}}, year = {2012}, pages = {51-61}, journal = {Planta}, volume = {236}, abstract = { Arabidopsis caffeoyl coenzyme A dependent O-methyltransferase 1 (CCoAOMT1) and caffeic acid O-methyltransferase 1 (COMT1) display a similar substrate profile although with distinct substrate preferences and are considered the key methyltransferases (OMTs) in the biosynthesis of lignin monomers, coniferyl and sinapoylalcohol. Whereas CCoAOMT1 displays a strong preference for caffeoyl coenzyme A, COMT1 preferentially methylates 5-hydroxyferuloyl CoA derivatives and also performs methylation of flavonols with vicinal aromatic dihydroxy groups, such as quercetin. Based on different knockout lines, phenolic profiling, and immunohistochemistry, we present evidence that both enzymes fulfil distinct, yet different tasks in Arabidopsis anthers. CCoAOMT1 besides its role in vascular tissues can be localized to the tapetum of young stamens, contributing to the biosynthesis of spermidine phenylpropanoid conjugates. COMT1, although present in the same organ, is not localized in the tapetum, but in two directly adjacent cells layers, the endothecium and the epidermal layer of stamens. In vivo localization and phenolic profiling of comt1 plants provide evidence that COMT1 neither contributes to the accumulation of spermidine phenylpropanoid conjugates nor to the flavonol glycoside pattern of pollen grains.} } @Article{IPB-1369, author = {Landgraf, R. and Schaarschmidt, S. and Hause, B.}, title = {{Repeated leaf wounding alters the colonization of Medicago truncatula roots by beneficial and pathogenic microorganisms.}}, year = {2012}, pages = {1344-1357}, journal = {Plant Cell \& Environment}, volume = {35 (7)}, abstract = { In nature, plants are subject to various stresses that are often accompanied by wounding of the aboveground tissues. As wounding affects plants locally and systemically, we investigated the impact of leaf wounding on interactions of Medicago truncatula with root-colonizing microorganisms, such as the arbuscular mycorrhizal (AM) fungus Glomus intraradices, the pathogenic oomycete Aphanomyces euteiches and the nitrogen-fixing bacterium Sinorhizobium meliloti. To obtain a long-lasting wound response, repeated wounding was performed and resulted in locally and systemically increased jasmonic acid (JA) levels accompanied by the expression of jasmonate-induced genes, among them the genes encoding allene oxide cyclase 1 (MtAOC1) and a putative cell wall-bound invertase (cwINV). After repeated wounding, colonization with the AM fungus was increased, suggesting a role of jasmonates as positive regulators of mycorrhization, whereas the interaction with the rhizobacterium was not affected. In contrast, wounded plants appeared to be less susceptible to pathogens which might be caused by JA-induced defence mechanisms. The effects of wounding on mycorrhization and pathogen infection could be partially mimicked by foliar application of JA. In addition to JA itself, the positive effect on mycorrhization might be mediated by systemically induced cwINV, which was previously shown to exhibit a regulatory function on interaction with AM fungi.} } @Article{IPB-1366, author = {Eschen-Lippold, L. and Landgraf, R. and Smolka, U. and Schulze, S. and Heilmann, M. and Heilmann, I. and Hause, G. and Rosahl, S.}, title = {{Activation of defense against \textit{Phytophthora infestans} in potato by down regulation of syntaxin gene expression}}, year = {2012}, pages = {985-996}, journal = {New Phytologist }, volume = {193}, } @Article{IPB-1230, author = {Zdyb, A. and Demchenko, K. and Heumann, J. and Mrosk, C. and Grzeganek, P. and Göbel, C. and Feussner, I. and Pawlowski, K. and Hause, B.}, title = {{Jasmonate biosynthesis in legume and actinorhizal nodules}}, year = {2011}, pages = {568-579 }, journal = {New Phytol}, volume = {189}, } @Article{IPB-1356, author = {Helber, N. and Wippel, K. and Sauer, N. and Schaarschmidt, S. and Hause, B. and Requena, N.}, title = {{A versatile monosaccharide transporter that operates in the arbuscular mycorrhizal fungus \textit{Glomus sp} is crucial for the symbiotic relationship with plants.}}, year = {2011}, pages = {3812-3823}, journal = {Plant Cell}, volume = {23}, } @Article{IPB-1264, author = {Mielke, K. and Forner, S. and Kramell, R. and Conrad, U. and Hause, B.}, title = {{Cell-specific visualization of jasmonates in wounded tomato and Arabidopsis leaves using jasmonate-specific antibodies}}, year = {2011}, pages = {1069-1080}, journal = {New Phytol}, volume = {190}, } @Article{IPB-1225, author = {Teutschbein, J. and Gross, W. and Nimtz, M. and Milkowski, C. and Hause, B. and Strack, D.}, title = {{Identification and localization of a lipase-like acyltransferase in phenylpropanoid metabolism of tomato (Solanum lycopersicum)}}, year = {2010}, pages = {38374-38381 }, journal = {J. Biol. Chem}, volume = {285}, } @Article{IPB-1226, author = {Breuillin, F. and Hajirezaei, M.-R. and Ahkami, A. and Favre, P. and Druege, U. and Hause, B. and Bucher, M. and Kretzschmar, T. and Bossolini, E. and Kuhlemeier, C. and Martinoia, E. and Franken, P. and Scholz, U. and Reinhardt, D.}, title = {{Phosphate systemically inhibits development of arbuscular mycorrhiza in Petunia hybrida and represses genes involved in mycorrhizal functioning}}, year = {2010}, pages = {1002-1017 }, journal = {Plant J}, volume = {64}, } @Article{IPB-1119, author = {Mrosk, C. and Forner, S. and Hause, G. and Küster, H. and Kopka, J. and Hause, B.}, title = {{Composite Medicago truncatula plants harbouring Agrobacterium rhizogenes-transformed roots reveal normal mycorrhization by Glomus intraradices}}, year = {2009}, pages = {3797-3807}, journal = {J. Exp. Bot}, volume = {60}, } @Article{IPB-1044, author = {Hohnjec, N. and Lenz, F. and Fehlberg, V. and Vieweg, M.F. and Baier, M.C. and Hause, B. and Küster, H.}, title = {{The signal peptide of the Medicago truncatulamodular nodulin MtNOD25 operates as an address label for the specific targeting of proteins to nitrogen-fixing symbiosomes}}, year = {2009}, pages = {63-72}, journal = {Mol. Plant Microbe In}, volume = {22}, } @Article{IPB-1090, author = {Bethke, G. and Unthan, T. and Uhrig, J.F. and Pöschl, Y. and Gust, A.A. and Scheel, D. and Lee, J.}, title = {{Flg22 regulates the release of an ethylene response factor substrate from MAP kinase 6 in Arabidopsis thaliana via ethylene signaling}}, year = {2009}, pages = {8067-72}, journal = {Proc Natl Acad Sci U S A}, volume = {106}, abstract = { Mitogen-activated protein kinase (MAPK)mediated responses are in part regulated by the repertoire of MAPK substrates, which is still poorly elucidated in plants. Here, the in vivo enzymesubstrate interaction of the Arabidopsis thaliana MAP kinase, MPK6, with an ethylene response factor (ERF104) is shown by fluorescence resonance energy transfer. The interaction was rapidly lost in response to flagellin-derived flg22 peptide. This complex disruption requires not only MPK6 activity, which also affects ERF104 stability via phosphorylation, but also ethylene signaling. The latter points to a novel role of ethylene in substrate release, presumably allowing the liberated ERF104 to access target genes. Microarray data show enrichment of GCC motifs in the promoters of ERF104up-regulated genes, many of which are stress related. ERF104 is a vital regulator of basal immunity, as altered expression in both erf104 and overexpressors led to more growth inhibition by flg22 and enhanced susceptibility to a non-adapted bacterial pathogen.} }