@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 McCaig, 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}, doi = {10.1104/pp.111.192658}, url = {https://dx.doi.org/10.1104/pp.111.192658}, volume = {158}, 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-1370, author = {Fellenberg, C. and van Ohlen, M. and Handrick, V. and Vogt, T.}, title = {{The role of CCoAOMT1 and COMT1 in Arabidopsis anthers}}, year = {2012}, pages = {51-61}, journal = {Planta}, doi = {10.1007/s00425-011-1586-6}, url = {https://dx.doi.org/10.1007/s00425-011-1586-6}, 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 Environ}, doi = {10.1111/j.1365-3040.2012.02495.x}, url = {https://dx.doi.org/10.1111/j.1365-3040.2012.02495.x}, volume = {35}, 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-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}, doi = {10.1093/jxb/ers261}, url = {https://dx.doi.org/10.1093/jxb/ers261}, 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 Coordinates Responses to Spodoptera Herbivory and Abiotic Stresses in Arabidopsis}}, year = {2012}, pages = {1159-1175}, journal = {Plant Physiol}, doi = {10.1104/pp.112.198150}, url = {https://dx.doi.org/10.1104/pp.112.198150}, volume = {159}, abstract = {In the interaction between Arabidopsis (Arabidopsis thaliana) and the generalist herbivorous insect Spodoptera littoralis, little is known about early events in defense signaling and their link to downstream phytohormone pathways. S. littoralis oral secretions induced both Ca2+ and phytohormone elevation in Arabidopsis. Plant gene expression induced by oral secretions revealed up-regulation of a gene encoding a calmodulin-like protein, CML42. Functional analysis of cml42 plants revealed more resistance to herbivory than in the wild type, because caterpillars gain less weight on the mutant, indicating that CML42 negatively regulates plant defense; cml42 also showed increased aliphatic glucosinolate content and hyperactivated transcript accumulation of the jasmonic acid (JA)-responsive genes VSP2 and Thi2.1 upon herbivory, which might contribute to increased resistance. CML42 up-regulation is negatively regulated by the jasmonate receptor Coronatine Insensitive1 (COI1), as loss of functional COI1 resulted in prolonged CML42 activation. CML42 thus acts as a negative regulator of plant defense by decreasing COI1-mediated JA sensitivity and the expression of JA-responsive genes and is independent of herbivory-induced JA biosynthesis. JA-induced Ca2+ elevation and root growth inhibition were more sensitive in cml42, also indicating higher JA perception. Our results indicate that CML42 acts as a crucial signaling component connecting Ca2+ and JA signaling. CML42 is localized to cytosol and nucleus. CML42 is also involved in abiotic stress responses, as kaempferol glycosides were down-regulated in cml42, and impaired in ultraviolet B resistance. Under drought stress, the level of abscisic acid accumulation was higher in cml42 plants. Thus, CML42 might serve as a Ca2+ sensor having multiple functions in insect herbivory defense and abiotic stress responses.} } @Article{IPB-1448, author = {Stegmann, M. and Anderson, R. G. and Ichimura, K. and Pecenkova, T. and Reuter, P. and Žárský, 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 Arabidopsis}}, year = {2012}, pages = {4703-4716}, journal = {Plant Cell}, doi = {10.1105/tpc.112.104463}, url = {http://www.plantcell.org/cgi/doi/10.1105/tpc.112.104463}, volume = {24}, 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-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 Phytophthora infestans in potato by down-regulation of syntaxin gene expression}}, year = {2012}, pages = {985-996}, journal = {New Phytol}, doi = {10.1111/j.1469-8137.2011.04024.x}, url = {https://dx.doi.org/10.1111/j.1469-8137.2011.04024.x}, volume = {193}, abstract = {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.} } @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 Glomus sp Is Crucial for the Symbiotic Relationship with Plants}}, year = {2011}, pages = {3812-3823}, journal = {Plant Cell}, doi = {10.1105/tpc.111.089813}, url = {https://dx.doi.org/10.1105/tpc.111.089813}, volume = {23}, abstract = {For more than 400 million years, plants have maintained a mutualistic symbiosis with arbuscular mycorrhizal (AM) fungi. This evolutionary success can be traced to the role of these fungi in providing plants with mineral nutrients, particularly phosphate. In return, photosynthates are given to the fungus, which support its obligate biotrophic lifestyle. Although the mechanisms involved in phosphate transfer have been extensively studied, less is known about the reciprocal transfer of carbon. Here, we present the high-affinity Monosaccharide Transporter2 (MST2) from Glomus sp with a broad substrate spectrum that functions at several symbiotic root locations. Plant cell wall sugars can efficiently outcompete the Glc uptake capacity of MST2, suggesting they can serve as alternative carbon sources. MST2 expression closely correlates with that of the mycorrhiza-specific PhosphateTransporter4 (PT4). Furthermore, reduction of MST2 expression using host-induced gene silencing resulted in impaired mycorrhiza formation, malformed arbuscules, and reduced PT4 expression. These findings highlight the symbiotic role of MST2 and support the hypothesis that the exchange of carbon for phosphate is tightly linked. Unexpectedly, we found that the external mycelium of AM fungi is able to take up sugars in a proton-dependent manner. These results imply that the sugar uptake system operating in this symbiosis is more complex than previously anticipated.} } @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}, doi = {10.1111/j.1469-8137.2010.03504.x}, url = {https://dx.doi.org/10.1111/j.1469-8137.2010.03504.x}, volume = {189}, abstract = {Jasmonic acid (JA) is a plant signalling compound that has been implicated in the regulation of mutualistic symbioses. In order to understand the spatial distribution of JA biosynthetic capacity in nodules of two actinorhizal species, Casaurina glauca and Datisca glomerata, and one legume, Medicago truncatula, we determined the localization of allene oxide cyclase (AOC) which catalyses a committed step in JA biosynthesis. In all nodule types analysed, AOC was detected exclusively in uninfected cells.The levels of JA were compared in the roots and nodules of the three plant species. The nodules and noninoculated roots of the two actinorhizal species, and the root systems of M. truncatula, noninoculated or nodulated with wild‐type Sinorhizobium meliloti or with mutants unable to fix nitrogen, did not show significant differences in JA levels. However, JA levels in all plant organs examined increased significantly on mechanical disturbance.To study whether JA played a regulatory role in the nodules of M. truncatula, composite plants containing roots expressing an MtAOC1‐sense or MtAOC1‐RNAi construct were inoculated with S. meliloti. Neither an increase nor reduction in AOC levels resulted in altered nodule formation.These data suggest that jasmonates are not involved in the development and function of root nodules.} } @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}, doi = {10.1111/j.1469-8137.2010.03638.x}, url = {https://dx.doi.org/10.1111/j.1469-8137.2010.03638.x}, volume = {190}, abstract = {Jasmonates are well‐characterized signals in the development of plants and their response to abiotic and biotic stresses, such as touch and wounding by herbivores. A gap in our knowledge on jasmonate‐induced processes, however, is the cellular localization of jasmonates.Here, a novel antibody‐based approach was developed to visualize jasmonates in cross‐sections of plant material. Antibodies raised in rabbits against BSA‐coupled jasmonic acid (JA) are specific for JA, its methyl ester and isoleucine conjugate. They do not bind to 12‐oxophytodienoic acid, 12‐hydoxy‐JA or coronatine. These antibodies were used in combination with newly established fixation and embedding methods.Jasmonates were rapidly and uniformly distributed within all cells near the site of damage of a mechanically wounded tomato (Solanum lycopersicum) leaf. Leaf tissue distally located to the wound site exhibited identical distribution, but had a lower signal intensity. The occurrence of jasmonates in all cell types of a wounded leaf was accompanied by transcript accumulation of early JA‐induced genes visualized by in situ hybridization.With these new antibodies, a powerful tool is available to detect cell‐specifically the occurrence of jasmonates in any jasmonate‐dependent stress response or developmental process of plants.} } @Article{IPB-1226, author = {Breuillin, F. and Schramm, J. and Hajirezaei, M. 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}, doi = {10.1111/j.1365-313X.2010.04385.x}, url = {https://dx.doi.org/10.1111/j.1365-313X.2010.04385.x}, volume = {64}, abstract = {Most terrestrial plants form arbuscular mycorrhiza (AM), mutualistic associations with soil fungi of the order Glomeromycota. The obligate biotrophic fungi trade mineral nutrients, mainly phosphate (Pi), for carbohydrates from the plants. Under conditions of high exogenous phosphate supply, when the plant can meet its own P requirements without the fungus, AM are suppressed, an effect which could be interpreted as an active strategy of the plant to limit carbohydrate consumption of the fungus by inhibiting its proliferation in the roots. However, the mechanisms involved in fungal inhibition are poorly understood. Here, we employ a transcriptomic approach to get insight into potential shifts in metabolic activity and symbiotic signalling, and in the defence status of plants exposed to high Pi levels. We show that in mycorrhizal roots of petunia, a similar set of symbiosis‐related genes is expressed as in mycorrhizal roots of Medicago, Lotus and rice. Pi acts systemically to repress symbiotic gene expression and AM colonization in the root. In established mycorrhizal roots, Pi repressed symbiotic gene expression rapidly, whereas the inhibition of colonization followed with a lag of more than a week. Taken together, these results suggest that Pi acts by repressing essential symbiotic genes, in particular genes encoding enzymes of carotenoid and strigolactone biosynthesis, and symbiosis‐associated phosphate transporters. The role of these effects in the suppression of symbiosis under high Pi conditions is discussed.} } @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}, doi = {10.1074/jbc.M110.171637}, url = {https://dx.doi.org/10.1074/jbc.M110.171637}, volume = {285}, abstract = {We have isolated an enzyme classified as chlorogenate: glucarate caffeoyltransferase (CGT) from seedlings of tomato (Solanum lycopersicum) that catalyzes the formation of caffeoylglucarate and caffeoylgalactarate using chlorogenate (5-O-caffeoylquinate) as acyl donor. Peptide sequences obtained by trypsin digestion and spectrometric sequencing were used to isolate the SlCGT cDNA encoding a protein of 380 amino acids with a putative targeting signal of 24 amino acids indicating an entry of the SlCGT into the secretory pathway. Immunogold electron microscopy revealed the localization of the enzyme in the apoplastic space of tomato leaves. Southern blot analysis of genomic cDNA suggests that SlCGT is encoded by a single-copy gene. The SlCGT cDNA was functionally expressed in Nicotiana benthamiana leaves and proved to confer chlorogenate-dependent caffeoyltransferase activity in the presence of glucarate. Sequence comparison of the deduced amino acid sequence identified the protein unexpectedly as a GDSL lipase-like protein, representing a new member of the SGNH protein superfamily. Lipases of this family employ a catalytic triad of Ser-Asp-His with Ser as nucleophile of the GDSL motif. Site-directed mutagenesis of each residue of the assumed respective SlCGT catalytic triad, however, indicated that the catalytic triad of the GDSL lipase is not essential for SlCGT enzymatic activity. SlCGT is therefore the first example of a GDSL lipase-like protein that lost hydrolytic activity and has acquired a completely new function in plant metabolism, functioning in secondary metabolism as acyltransferase in synthesis of hydroxycinnamate esters by employing amino acid residues different from the lipase catalytic triad.} } @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-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-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.} }