@Article{IPB-2532, author = {Mitra, D. and Kumari, P. and Quegwer, J. and Klemm, S. and Möller, B. and Poeschl, Y. and Pflug, P. and Stamm, G. and Abel, S. and Bürstenbinder, K. and}, title = {{Microtubule-associated protein IQ67 DOMAIN5 regulates interdigitation of leaf pavement cells in Arabidopsis thaliana}}, year = {2018}, journal = {bioRxiv}, doi = {10.1101/268466}, abstract = {Plant microtubules form a highly dynamic intracellular network with important roles for regulating cell division, cell proliferation and cell morphology. Its organization and dynamics are coordinated by various microtubule-associated proteins (MAPs) that integrate environmental and developmental stimuli to fine-tune and adjust cytoskeletal arrays. IQ67 DOMAIN (IQD) proteins recently emerged as a class of plant-specific MAPs with largely unknown functions. Here, using a reverse genetics approach, we characterize Arabidopsis IQD5 in terms of its expression domains, subcellular localization and biological functions. We show that IQD5 is expressed mostly in vegetative tissues, where it localizes to cortical microtubule arrays. Our phenotypic analysis of iqd5 loss-of-function lines reveals functions of IQD5 in pavement cell (PC) shape morphogenesis, as indicated by reduced interdigitation of neighboring cells in the leaf epidermis of iqd5 mutants. Histochemical analysis of cell wall composition further suggests reduced rates of cellulose deposition in anticlinal cell walls, which correlate with reduced asymmetric expansion. Lastly, we provide evidence for IQD5-dependent recruitment of calmodulin calcium sensors to cortical microtubule arrays. Our work thus identifies IQD5 as a novel player in PC shape regulation, and, for the first time, links calcium signaling to developmental processes that regulate multi-polar growth in PCs.} } @Article{IPB-2528, author = {Anwer, M. U. and Davis, A. and Davis, S. J. and Quint, M. and}, title = {{Photoperiod sensing of the circadian clock is controlled by EARLY FLOWERING 3 and GIGANTEA}}, year = {2018}, journal = {bioRxiv}, doi = {10.1101/321794}, abstract = {ELF3 and GI are two important components of the Arabidopsis circadian clock. They are not only essential for the oscillator function but are also pivotal in mediating light inputs to the oscillator. Lack of either results in a defective oscillator causing severely compromised output pathways, such as photoperiodic flowering and hypocotyl elongation. Although single loss of function mutants of ELF3 and GI have been well-studied, their genetic interaction remains unclear. We generated an elf3 gi double mutant to study their genetic relationship in clock-controlled growth and phase transition phenotypes. We found that ELF3 and GI repress growth differentially during the night and the day, respectively. Circadian clock assays revealed that ELF3 and GI are essential Zeitnehmers that enable the oscillator to synchronize the endogenous cellular mechanisms to external environmental signals. In their absence, the circadian oscillator fails to synchronize to the light-dark cycles even under diurnal conditions. Consequently, clock-mediated photoperiod-responsive growth and development is completely lost in plants lacking both genes, suggesting that ELF3 and GI together convey photoperiod sensing to the central oscillator. Since ELF3 and GI are conserved across flowering plants and represent important breeding and domestication targets, our data highlight the possibility of developing photoperiod-insensitive crops by adjusting the allelic combination of these two key genes.} } @Article{IPB-816, author = {Nishiyama, T. and Sakayama, H. and de Vries, J. and Buschmann, H. and Saint-Marcoux, D. and Ullrich, K. K. and Haas, F. B. and Vanderstraeten, L. and Becker, D. and Lang, D. and Vosolsobě, S. and Rombauts, S. and Wilhelmsson, P. K. and Janitza, P. and Kern, R. and Heyl, A. and Rümpler, F. and Calderón Villalobos, L. I. A. and Clay, J. M. and Skokan, R. and Toyoda, A. and Suzuki, Y. and Kagoshima, H. and Schijlen, E. and Tajeshwar, N. and Catarino, B. and Hetherington, A. J. and Saltykova, A. and Bonnot, C. and Breuninger, H. and Symeonidi, A. and Radhakrishnan, G. V. and Van Nieuwerburgh, F. and Deforce, D. and Chang, C. and Karol, K. G. and Hedrich, R. and Ulvskov, P. and Glöckner, G. and Delwiche, C. F. and Petrášek, J. and Van de Peer, Y. and Friml, J. and Beilby, M. and Dolan, L. and Kohara, Y. and Sugano, S. and Fujiyama, A. and Delaux, P.-M. and Quint, M. and Theißen, G. and Hagemann, M. and Harholt, J. and Dunand, C. and Zachgo, S. and Langdale, J. and Maumus, F. and Van Der Straeten, D. and Gould, S. B. and Rensing, S. A. and}, title = {{The Chara Genome: Secondary Complexity and Implications for Plant Terrestrialization}}, year = {2018}, pages = {448-464.e24}, journal = {Cell}, doi = {10.1016/j.cell.2018.06.033}, volume = {174}, abstract = {Land plants evolved from charophytic algae, among which Charophyceae possess the most complex body plans. We present the genome of Chara braunii; comparison of the genome to those of land plants identified evolutionary novelties for plant terrestrialization and land plant heritage genes. C. braunii employs unique xylan synthases for cell wall biosynthesis, a phragmoplast (cell separation) mechanism similar to that of land plants, and many phytohormones. C. braunii plastids are controlled via land-plant-like retrograde signaling, and transcriptional regulation is more elaborate than in other algae. The morphological complexity of this organism may result from expanded gene families, with three cases of particular note: genes effecting tolerance to reactive oxygen species (ROS), LysM receptor-like kinases, and transcription factors (TFs). Transcriptomic analysis of sexual reproductive structures reveals intricate control by TFs, activity of the ROS gene network, and the ancestral use of plant-like storage and stress protection proteins in the zygote.} } @Article{IPB-798, author = {Krägeloh, T. and Cavalleri, J. M. V. and Ziegler, J. and Sander, J. and Terhardt, M. and Breves, G. and Cehak, A. and}, title = {{Identification of hypoglycin A binding adsorbents as potential preventive measures in co-grazers of atypical myopathy affected horses}}, year = {2018}, pages = {220-227}, journal = {Equine Vet. J.}, doi = {10.1111/evj.12723}, volume = {50}, abstract = {BackgroundIntestinal absorption of hypoglycin A (HGA) and its metabolism are considered major prerequisites for atypical myopathy (AM). The increasing incidence and the high mortality rate of AM urgently necessitate new therapeutic and/or preventative approaches.ObjectivesTo identify a substance for oral administration capable of binding HGA in the intestinal lumen and effectively reducing the intestinal absorption of the toxin.Study designExperimental in vitro study.MethodsSubstances commonly used in equine practice (activated charcoal composition, di‐tri‐octahedral smectite, mineral oil and activated charcoal) were tested for their binding capacity for HGA using an in vitro incubation method. The substance most effective in binding HGA was subsequently tested for its potential to reduce intestinal HGA absorption. Jejunal tissues of 6 horses were incubated in Ussing chambers to determine mucosal uptake, tissue accumulation, and serosal release of HGA in the presence and absence of the target substance. Potential intestinal metabolism in methylenecyclopropyl acetic acid (MCPA)‐conjugates was investigated by analysing their concentrations in samples from the Ussing chambers.ResultsActivated charcoal composition and activated charcoal were identified as potent HGA binding substances with dose and pH dependent binding capacity. There was no evidence of intestinal HGA metabolism.Main limitationsBinding capacity of adsorbents was tested in vitro using aqueous solutions, and in vivo factors such as transit time and composition of intestinal content, may affect adsorption capacity after oral administration.ConclusionsFor the first time, this study identifies substances capable of reducing HGA intestinal absorption. This might have major implications as a preventive measure in cograzers of AM affected horses but also in horses at an early stage of intoxication.} } @Article{IPB-796, author = {Jung, J.-Y. and Ried, M. K. and Hothorn, M. and Poirier, Y. and}, title = {{Control of plant phosphate homeostasis by inositol pyrophosphates and the SPX domain}}, year = {2018}, pages = {156-162}, journal = {Curr. Opin. Biotech.}, doi = {10.1016/j.copbio.2017.08.012}, volume = {49}, abstract = {Proteins containing a SPX domain are involved in phosphate (Pi) homeostasis, including Pi transport and adaptation to Pi deficiency. The SPX domain harbors a basic surface binding Pi at low affinity and inositol pyrophosphates (PP-InsPs) at high affinity. Genetic and biochemical studies revealed that PP-InsPs serve as ligands for the SPX domain. Residues in the PHO1 SPX domain involved in PP-InsPs binding are critical for its Pi export activity, and the interaction between SPX proteins and the PHR1 transcription factor, which results in PHR1 inactivation, is promoted by PP-InsPs. Changes in PP-InsPs levels in response to Pi deficiency may thus contribute to the adaptation of plants to stress via the modulation of the activity of SPX-containing proteins and their interactors. Modulating PP-InsP levels or the affinity/specificity of the SPX domain for PP-InsP could potentially be used to engineer crops to maintain high yield under reduced Pi fertilizer input.} } @Article{IPB-795, author = {Jablonická, V. and Ziegler, J. and Vatehová, Z. and Lišková, D. and Heilmann, I. and Obložinský, M. and Heilmann, M. and}, title = {{Inhibition of phospholipases influences the metabolism of wound-induced benzylisoquinoline alkaloids in Papaver somniferum L.}}, year = {2018}, pages = {1-8}, journal = {J. Plant Physiol.}, doi = {10.1016/j.jplph.2018.01.007}, volume = {223}, abstract = {Benzylisoquinoline alkaloids (BIAs) are important secondary plant metabolites and include medicinally relevant drugs, such as morphine or codeine. As the de novo synthesis of BIA backbones is (still) unfeasible, to date the opium poppy plant Papaver somniferum L. represents the main source of BIAs. The formation of BIAs is induced in poppy plants by stress conditions, such as wounding or salt treatment; however, the details about regulatory processes controlling BIA formation in opium poppy are not well studied. Environmental stresses, such as wounding or salinization, are transduced in plants by phospholipid-based signaling pathways, which involve different classes of phospholipases. Here we investigate whether pharmacological inhibition of phospholipase A2 (PLA2, inhibited by aristolochic acid (AA)) or phospholipase D (PLD; inhibited by 5-fluoro-2-indolyl des-chlorohalopemide (FIPI)) in poppy plants influences wound-induced BIA accumulation and the expression of key biosynthetic genes. We show that inhibition of PLA2 results in increased morphinan biosynthesis concomitant with reduced production of BIAs of the papaverine branch, whereas inhibition of PLD results in increased production of BIAs of the noscapine branch. The data suggest that phospholipid-dependent signaling pathways contribute to the activation of morphine biosynthesis at the expense of the production of other BIAs in poppy plants. A better understanding of the effectors and the principles of regulation of alkaloid biosynthesis might be the basis for the future genetic modification of opium poppy to optimize BIA production.} } @Article{IPB-794, author = {Iglesias, M. J. and Terrile, M. C. and Correa-Aragunde, N. and Colman, S. L. and Izquierdo-Álvarez, A. and Fiol, D. F. and París, R. and Sánchez-López, N. and Marina, A. and Calderón Villalobos, L. I. A. and Estelle, M. and Lamattina, L. and Martínez-Ruiz, A. and Casalongué, C. A. and}, title = {{Regulation of SCFTIR1/AFBs E3 ligase assembly by S-nitrosylation of Arabidopsis SKP1-like1 impacts on auxin signaling}}, year = {2018}, pages = {200-210}, journal = {Redox Biol.}, doi = {10.1016/j.redox.2018.07.003}, volume = {18}, abstract = {The F-box proteins (FBPs) TIR1/AFBs are the substrate recognition subunits of SKP1–cullin–F-box (SCF) ubiquitin ligase complexes and together with Aux/IAAs form the auxin co-receptor. Although tremendous knowledge on auxin perception and signaling has been gained in the last years, SCFTIR1/AFBs complex assembly and stabilization are emerging as new layers of regulation. Here, we investigated how nitric oxide (NO), through S-nitrosylation of ASK1 is involved in SCFTIR1/AFBs assembly. We demonstrate that ASK1 is S-nitrosylated and S-glutathionylated in cysteine (Cys) 37 and Cys118 residues in vitro. Both, in vitro and in vivo protein-protein interaction assays show that NO enhances ASK1 binding to CUL1 and TIR1/AFB2, required for SCFTIR1/AFB2 assembly. In addition, we demonstrate that Cys37 and Cys118 are essential residues for proper activation of auxin signaling pathway in planta. Phylogenetic analysis revealed that Cys37 residue is only conserved in SKP proteins in Angiosperms, suggesting that S-nitrosylation on Cys37 could represent an evolutionary adaption for SKP1 function in flowering plants. Collectively, these findings indicate that multiple events of redox modifications might be part of a fine-tuning regulation of SCFTIR1/AFBs for proper auxin signal transduction.} } @Article{IPB-793, author = {Ibañez, C. and Delker, C. and Martinez, C. and Bürstenbinder, K. and Janitza, P. and Lippmann, R. and Ludwig, W. and Sun, H. and James, G. V. and Klecker, M. and Grossjohann, A. and Schneeberger, K. and Prat, S. and Quint, M. and}, title = {{Brassinosteroids Dominate Hormonal Regulation of Plant Thermomorphogenesis via BZR1}}, year = {2018}, pages = {303-310.e3}, journal = {Curr. Biol.}, doi = {10.1016/j.cub.2017.11.077}, volume = {28}, abstract = {Thermomorphogenesis is defined as the suite of morphological changes that together are likely to contribute to adaptive growth acclimation to usually elevated ambient temperature [1, 2]. While many details of warmth-induced signal transduction are still elusive, parallels to light signaling recently became obvious (reviewed in [3]). It involves photoreceptors that can also sense changes in ambient temperature [3, 4, 5] and act, for example, by repressing protein activity of the central integrator of temperature information PHYTOCHROME-INTERACTING FACTOR 4 (PIF4 [6]). In addition, PIF4 transcript accumulation is tightly controlled by the evening complex member EARLY FLOWERING 3 [7, 8]. According to the current understanding, PIF4 activates growth-promoting genes directly but also via inducing auxin biosynthesis and signaling, resulting in cell elongation. Based on a mutagenesis screen in the model plant Arabidopsis thaliana for mutants with defects in temperature-induced hypocotyl elongation, we show here that both PIF4 and auxin function depend on brassinosteroids. Genetic and pharmacological analyses place brassinosteroids downstream of PIF4 and auxin. We found that brassinosteroids act via the transcription factor BRASSINAZOLE RESISTANT 1 (BZR1), which accumulates in the nucleus at high temperature, where it induces expression of growth-promoting genes. Furthermore, we show that at elevated temperature BZR1 binds to the promoter of PIF4, inducing its expression. These findings suggest that BZR1 functions in an amplifying feedforward loop involved in PIF4 activation. Although numerous negative regulators of PIF4 have been described, we identify BZR1 here as a true temperature-dependent positive regulator of PIF4, acting as a major growth coordinator.} } @Article{IPB-785, author = {García, M. L. and Bó, E. D. and da Graça, J. V. and Gago-Zachert, S. and Hammond, J. and Moreno, P. and Natsuaki, T. and Pallás, V. and Navarro, J. A. and Reyes, C. A. and Luna, G. R. and Sasaya, T. and Tzanetakis, I. E. and Vaira, A. M. and Verbeek, M. and ICTV Report Consortium, . and}, title = {{Corrigendum: ICTV Virus Taxonomy Profile: Ophioviridae}}, year = {2018}, pages = {949-949}, journal = {J. Gen. Virol.}, doi = {10.1099/jgv.0.001093}, volume = {99}, } @Article{IPB-784, author = {Gantner, J. and Ordon, J. and Ilse, T. and Kretschmer, C. and Gruetzner, R. and Löfke, C. and Dagdas, Y. and Bürstenbinder, K. and Marillonnet, S. and Stuttmann, J. and}, title = {{Peripheral infrastructure vectors and an extended set of plant parts for the Modular Cloning system}}, year = {2018}, pages = {e0197185}, journal = {PLOS ONE}, doi = {10.1371/journal.pone.0197185}, volume = {13}, abstract = {Standardized DNA assembly strategies facilitate the generation of multigene constructs from collections of building blocks in plant synthetic biology. A common syntax for hierarchical DNA assembly following the Golden Gate principle employing Type IIs restriction endonucleases was recently developed, and underlies the Modular Cloning and GoldenBraid systems. In these systems, transcriptional units and/or multigene constructs are assembled from libraries of standardized building blocks, also referred to as phytobricks, in several hierarchical levels and by iterative Golden Gate reactions. Here, a toolkit containing further modules for the novel DNA assembly standards was developed. Intended for use with Modular Cloning, most modules are also compatible with GoldenBraid. Firstly, a collection of approximately 80 additional phytobricks is provided, comprising e.g. modules for inducible expression systems, promoters or epitope tags. Furthermore, DNA modules were developed for connecting Modular Cloning and Gateway cloning, either for toggling between systems or for standardized Gateway destination vector assembly. Finally, first instances of a “peripheral infrastructure” around Modular Cloning are presented: While available toolkits are designed for the assembly of plant transformation constructs, vectors were created to also use coding sequence-containing phytobricks directly in yeast two hybrid interaction or bacterial infection assays. The presented material will further enhance versatility of hierarchical DNA assembly strategies.} } @Article{IPB-851, author = {Wasternack, C. and Feussner, I. and}, title = {{The Oxylipin Pathways: Biochemistry and Function}}, year = {2018}, pages = {363-386}, journal = {Annu. Rev. Plant Biol.}, doi = {10.1146/annurev-arplant-042817-040440}, volume = {69}, abstract = {Plant oxylipins form a constantly growing group of signaling molecules that comprise oxygenated fatty acids and metabolites derived therefrom. In the last decade, the understanding of biosynthesis, metabolism, and action of oxylipins, especially jasmonates, has dramatically improved. Additional mechanistic insights into the action of enzymes and insights into signaling pathways have been deepened for jasmonates. For other oxylipins, such as the hydroxy fatty acids, individual signaling properties and cross talk between different oxylipins or even with additional phytohormones have recently been described. This review summarizes recent understanding of the biosynthesis, regulation, and function of oxylipins.} } @Article{IPB-850, author = {Wasternack, C. and Strnad, M. and}, title = {{Jasmonates: News on Occurrence, Biosynthesis, Metabolism and Action of an Ancient Group of Signaling Compounds}}, year = {2018}, pages = {2539}, journal = {Int. J. Mol. Sci.}, doi = {10.3390/ijms19092539}, volume = {19}, abstract = {Jasmonic acid (JA) and its related derivatives are ubiquitously occurring compounds of land plants acting in numerous stress responses and development. Recent studies on evolution of JA and other oxylipins indicated conserved biosynthesis. JA formation is initiated by oxygenation of α-linolenic acid (α-LeA, 18:3) or 16:3 fatty acid of chloroplast membranes leading to 12-oxo-phytodienoic acid (OPDA) as intermediate compound, but in Marchantiapolymorpha and Physcomitrellapatens, OPDA and some of its derivatives are final products active in a conserved signaling pathway. JA formation and its metabolic conversion take place in chloroplasts, peroxisomes and cytosol, respectively. Metabolites of JA are formed in 12 different pathways leading to active, inactive and partially active compounds. The isoleucine conjugate of JA (JA-Ile) is the ligand of the receptor component COI1 in vascular plants, whereas in the bryophyte M. polymorpha COI1 perceives an OPDA derivative indicating its functionally conserved activity. JA-induced gene expressions in the numerous biotic and abiotic stress responses and development are initiated in a well-studied complex regulation by homeostasis of transcription factors functioning as repressors and activators.} } @Article{IPB-849, author = {Wasternack, C. and Hause, B. and}, title = {{A Bypass in Jasmonate Biosynthesis – the OPR3-independent Formation}}, year = {2018}, pages = {276-279}, journal = {Trends Plant Sci.}, doi = {10.1016/j.tplants.2018.02.011}, volume = {23}, abstract = {For the first time in 25 years, a new pathway for biosynthesis of jasmonic acid (JA) has been identified. JA production takes place via 12-oxo-phytodienoic acid (OPDA) including reduction by OPDA reductases (OPRs). A loss-of-function allele, opr3-3, revealed an OPR3-independent pathway converting OPDA to JA.} } @Article{IPB-757, author = {Bagchi, R. and Melnyk, C. W. and Christ, G. and Winkler, M. and Kirchsteiner, K. and Salehin, M. and Mergner, J. and Niemeyer, M. and Schwechheimer, C. and Calderón Villalobos, L. I. A. and Estelle, M. and}, title = {{The Arabidopsis ALF4 protein is a regulator of SCF E3 ligases}}, year = {2018}, pages = {255-268}, journal = {EMBO J.}, doi = {10.15252/embj.201797159}, volume = {37}, abstract = {The cullin‐RING E3 ligases (CRLs) regulate diverse cellular processes in all eukaryotes. CRL activity is controlled by several proteins or protein complexes, including NEDD8, CAND1, and the CSN. Recently, a mammalian protein called Glomulin (GLMN) was shown to inhibit CRLs by binding to the RING BOX (RBX1) subunit and preventing binding to the ubiquitin‐conjugating enzyme. Here, we show that Arabidopsis ABERRANT LATERAL ROOT FORMATION4 (ALF4) is an ortholog of GLMN. The alf4 mutant exhibits a phenotype that suggests defects in plant hormone response. We show that ALF4 binds to RBX1 and inhibits the activity of SCFTIR1, an E3 ligase responsible for degradation of the Aux/IAA transcriptional repressors. In vivo, the alf4 mutation destabilizes the CUL1 subunit of the SCF. Reduced CUL1 levels are associated with increased levels of the Aux/IAA proteins as well as the DELLA repressors, substrate of SCFSLY1. We propose that the alf4 phenotype is partly due to increased levels of the Aux/IAA and DELLA proteins.} } @Article{IPB-760, author = {Bochnia, M. and Scheidemann, W. and Ziegler, J. and Sander, J. and Vollstedt, S. and Glatter, M. and Janzen, N. and Terhardt, M. and Zeyner, A. and}, title = {{Predictive value of hypoglycin A and methylencyclopropylacetic acid conjugates in a horse with atypical myopathy in comparison to its cograzing partners}}, year = {2018}, pages = {24-28}, journal = {Equine Vet. Educ.}, doi = {10.1111/eve.12596}, volume = {30}, abstract = {Hypoglycin A (HGA) was detected in blood and urine of a horse suffering from atypical myopathy (AM; Day 2, serum, 8290 μg/l; urine: Day 1, 574, Day 2, 742 μg/l) and in its cograzing partners with a high variability (46–1570 μg/l serum). Over the period of disease, the level of the toxic metabolites (methylencyclopropylacetic acid [MCPA]‐conjugates) increased in body fluids of the AM horse (MCPA‐carnitine: Day 2, 0.246, Day 3, 0.581 μmol/l serum; MCPA‐carnitine: Day 2, 0.621, Day 3, 0.884 μmol/mmol creatinine in urine) and HGA decreased rapidly (Day 3, 2430 μg/l serum). In cograzing horses MCPA‐conjugates were not detected. HGA in seeds ranged from 268 to 367 μg/g. Although HGA was present in body fluids of healthy cograzing horses, MCPA‐conjugates were not detectable, in contrast to the AM horse. Therefore, increasing concentrations of MCPA‐conjugates are supposed to be linked with the onset of AM and both parameters seem to indicate the clinical stage of disease. However, detection of HGA in body fluids of cograzing horses might be a promising step in preventing the disease.} } @Article{IPB-2292, author = {Ziegler, J. and Stenzel, I. and Hause, B. and Maucher, H. and Hamberg, M. and Grimm, R. and Ganal, M. and Wasternack, C. and}, title = {{Molecular Cloning of Allene Oxide Cyclase}}, year = {2000}, pages = {19132-19138}, journal = {J. Biol. Chem.}, doi = {10.1074/jbc.M002133200}, volume = {275}, abstract = {Allene oxide cyclase (EC 5.3.99.6) catalyzes the stereospecific cyclization of an unstable allene oxide to (9S,13S)-12-oxo-(10,15Z)-phytodienoic acid, the ultimate precursor of jasmonic acid. This dimeric enzyme has previously been purified, and two almost identical N-terminal peptides were found, suggesting allene oxide cyclase to be a homodimeric protein. Furthermore, the native protein was N-terminally processed. Using degenerate primers, a polymerase chain reaction fragment could be generated from tomato, which was further used to isolate a full-length cDNA clone of 1 kilobase pair coding for a protein of 245 amino acids with a molecular mass of 26 kDa. Whereas expression of the whole coding region failed to detect allene oxide cyclase activity, a 5′-truncated protein showed high activity, suggesting that additional amino acids impair the enzymatic function. Steric analysis of the 12-oxophytodienoic acid formed by the recombinant enzyme revealed exclusive (\>99%) formation of the 9S,13Senantiomer. Exclusive formation of this enantiomer was also found in wounded tomato leaves. Southern analysis and genetic mapping revealed the existence of a single gene for allene oxide cyclase located on chromosome 2 of tomato. Inspection of the N terminus revealed the presence of a chloroplastic transit peptide, and the location of allene oxide cyclase protein in that compartment could be shown by immunohistochemical methods. Concomitant with the jasmonate levels, the accumulation of allene oxide cyclase mRNA was transiently induced after wounding of tomato leaves.} } @Article{IPB-2289, author = {Weichert, H. and Kolbe, A. and Wasternack, C. and Feussner, I. and}, title = {{Formation of 4-hydroxy-2-alkenals in barley leaves}}, year = {2000}, pages = {850-851}, journal = {Biochem. Soc. Trans.}, doi = {10.1042/bst0280850}, volume = {28}, abstract = {In barley leaves 13-lipoxygenases are induced by jasmonates. This leads to induction of lipid peroxidation. Here we show by in vitro studies that these processes may further lead to autoxidative formation of (2E)-4-hydroxy-2-hexenal from (3Z)-hexenal.} } @Article{IPB-2288, author = {Wasternack, C. and Hause, B. and}, title = {{Stressabwehr und Entwicklung: Jasmonate — chemische Signale in Pflanzen}}, year = {2000}, pages = {312-320}, journal = {Biologie in unserer Zeit}, doi = {10.1002/1521-415X(200011)30:6<312::AID-BIUZ312>3.0.CO;2-8}, volume = {30}, abstract = {Chemische Signale wurden bereits im 19.Jahrhundert als Regulatoren von Wachstum und Entwicklung der Pflanzen postuliert.In den letzten 70 Jahren wurde die Wirkungsweise der klassischen Pflanzenhormone wie der Auxine, Gibberelline, Cytokinine, Ethylen und Abscisinsäure aufgeklärt. Doch erst im letzten Jahrzehnt entdeckte man die Bedeutung der Brassinosteroide, der Peptidhormone und der Jasmonate.} } @Article{IPB-2244, author = {Abel, S. and Nürnberger, T. and Ahnert, V. and Krauss, G.-J. and Glund, K. and}, title = {{Induction of an Extracellular Cyclic Nucleotide Phosphodiesterase as an Accessory Ribonucleolytic Activity during Phosphate Starvation of Cultured Tomato Cells}}, year = {2000}, pages = {543-552}, journal = {Plant Physiol.}, doi = {10.1104/pp.122.2.543}, volume = {122}, abstract = {During growth under conditions of phosphate limitation, suspension-cultured cells of tomato (Lycopersicon esculentum Mill.) secrete phosphodiesterase activity in a similar fashion to phosphate starvation-inducible ribonuclease (RNase LE), a cyclizing endoribonuclease that generates 2′:3′-cyclic nucleoside monophosphates (NMP) as its major monomeric products (T. Nürnberger, S. Abel, W. Jost, K. Glund [1990] Plant Physiol 92: 970–976). Tomato extracellular phosphodiesterase was purified to homogeneity from the spent culture medium of phosphate-starved cells and was characterized as a cyclic nucleotide phosphodiesterase. The purified enzyme has a molecular mass of 70 kD, a pH optimum of 6.2, and an isoelectric point of 8.1. The phosphodiesterase preparation is free of any detectable deoxyribonuclease, ribonuclease, and nucleotidase activity. Tomato extracellular phosphodiesterase is insensitive to EDTA and hydrolyzes with no apparent base specificity 2′:3′-cyclic NMP to 3′-NMP and the 3′:5′-cyclic isomers to a mixture of 3′-NMP and 5′-NMP. Specific activities of the enzyme are 2-fold higher for 2′:3′-cyclic NMP than for 3′:5′-cyclic isomers. Analysis of monomeric products of sequential RNA hydrolysis with purified RNase LE, purified extracellular phosphodiesterase, and cleared −Pi culture medium as a source of 3′-nucleotidase activity indicates that cyclic nucleotide phosphodiesterase functions as an accessory ribonucleolytic activity that effectively hydrolyzes primary products of RNase LE to substrates for phosphate-starvation-inducible phosphomonoesterases. Biosynthetical labeling of cyclic nucleotide phopshodiesterase upon phosphate starvation suggests de novo synthesis and secretion of a set of nucleolytic enzymes for scavenging phosphate from extracellular RNA substrates.} } @Article{IPB-2271, author = {Miersch, O. and Wasternack, C. and}, title = {{Octadecanoid and Jasmonate Signaling in Tomato (Lycopersicon esculentum Mill.) Leaves: Endogenous Jasmonates Do Not Induce Jasmonate Biosynthesis}}, year = {2000}, pages = {715-722}, journal = {Biol. Chem.}, doi = {10.1515/BC.2000.092}, volume = {381}, abstract = {Jasmonates and their precursors, the octadecanoids, are signals in stress-induced alteration of gene expression. Several mRNAs coding for enzymes of jasmonic acid (JA) biosynthesis are up-regulated upon JA treatment or endogenous increase of the JA level. Here we investigated the positive feedback of endogenous JA on JA formation, as well as its β-oxidation steps. JA-responsive gene expression was recorded in terms of proteinase inhibitor2 (pin2) mRNA accumulation. JA formed upon treatment of tomato (Lycopersicon esculentum cv. Moneymaker) leaves with JA derivatives carrying different lengths of the carboxylic acid side chain was quantified by gas chromatography-mass spectrometry (GC-MS). The data revealed that β-oxidation of the side chain occurs up to a butyric acid moiety. The amount of JA formed from side-chain modified JA derivatives correlated with pin2-mRNA accumulation. JA derivatives with a carboxylic side chain of 3, 5 or 7 carbon atoms were unable to form JA and to express on pin2, whereas evennumbered derivatives were active.After treatment of tomato leaves with (10-2H)-(–)-12-oxophytoenoic acid, (4-2H)-(–)-JA and its methyl ester were formed and could be quantified separately from the endogenously nonlabeled JA pool by GC-MS analysis via isotopic discrimination. The level of 8 nmol per g fresh weight JA and its methyl ester originated exclusively from labeled 12-oxophytoenic acid. This and further data indicate that endogenous synthesis of the JA precursor 12-oxophytodienoic acid, as well as of JA and its methyl ester, are not induced in tomato leaves, suggesting that positive feedback in JA biosynthesis does not function in vivo.} } @Article{IPB-2270, author = {Maucher, H. and Hause, B. and Feussner, I. and Ziegler, J. and Wasternack, C. and}, title = {{Allene oxide synthases of barley (Hordeum vulgare cv. Salome): tissue specific regulation in seedling development}}, year = {2000}, pages = {199-213}, journal = {Plant J.}, doi = {10.1046/j.1365-313x.2000.00669.x}, volume = {21}, abstract = {Allene oxide synthase (AOS) is the first enzyme in the lipoxygenase (LOX) pathway which leads to formation of jasmonic acid (JA). Two full‐length cDNAs of AOS designated as AOS1 and AOS2, respectively, were isolated from barley (H. vulgare cv. Salome) leaves, which represent the first AOS clones from a monocotyledonous species. For AOS1, the open reading frame encompasses 1461 bp encoding a polypeptide of 487 amino acids with calculated molecular mass of 53.4 kDa and an isoelectric point of 9.3, whereas the corresponding data of AOS2 are 1443 bp, 480 amino acids, 52.7 kDa and 7.9. Southern blot analysis revealed at least two genes. Despite the lack of a putative chloroplast signal peptide in both sequences, the protein co‐purified with chloroplasts and was localized within chloroplasts by immunocytochemical analysis. The barley AOSs, expressed in bacteria as active enzymes, catalyze the dehydration of LOX‐derived 9‐ as well as 13‐hydroperoxides of polyenoic fatty acids to the unstable allene oxides. In leaves, AOS mRNA accumulated upon treatment with jasmonates, octadecanoids and metabolizable carbohydrates, but not upon floating on abscisic acid, NaCl, Na‐salicylate or infection with powdery mildew. In developing seedlings, AOS mRNA strongly accumulated in the scutellar nodule, but less in the leaf base. Both tissues exhibited elevated JA levels. In situ hybridizations revealed the preferential occurrence of AOS mRNA in parenchymatic cells surrounding the vascular bundles of the scutellar nodule and in the young convoluted leaves as well as within the first internode. The properties of both barley AOSs, their up‐regulation of their mRNAs and their tissue specific expression suggest a role during seedling development and jasmonate biosynthesis.} } @Article{IPB-2265, author = {Kramell, R. and Miersch, O. and Atzorn, R. and Parthier, B. and Wasternack, C. and}, title = {{Octadecanoid-Derived Alteration of Gene Expression and the “Oxylipin Signature” in Stressed Barley Leaves. Implications for Different Signaling Pathways}}, year = {2000}, pages = {177-188}, journal = {Plant Physiol.}, doi = {10.1104/pp.123.1.177}, volume = {123}, abstract = {Stress-induced gene expression in barley (Hordeum vulgare cv Salome) leaves has been correlated with temporally changing levels of octadecanoids and jasmonates, quantified by means of gas chromatography/mass spectrometry-single ion monitoring. Application of sorbitol-induced stress led to a low and transient rise of jasmonic acid (JA), its precursor 12-oxophytodienoic acid (OPDA), and the methyl esters JAME and OPDAME, respectively, followed by a large increase in their levels. JA and JAME peaked between 12 and 16 h, about 4 h before OPDA and OPDAME. However, OPDA accumulated up to a 2.5-fold higher level than the other compounds. Dihomo-JA and 9,13-didehydro-OPDA were identified as minor components. Kinetic analyses revealed that a transient threshold of jasmonates or octadecanoids is necessary and sufficient to initiate JA-responsive gene expression. Although OPDA and OPDAME applied exogenously were metabolized to JA in considerable amounts, both of them can induce gene expression, as evidenced by those genes that did not respond to endogenously formed JA. Also, coronatine induces JA-responsive genes independently from endogenous JA. Application of deuterated JA showed that endogenous synthesis of JA is not induced by JA treatment. The data are discussed in terms of distinct signaling pathways.} } @Article{IPB-2257, author = {Hause, B. and Stenzel, I. and Miersch, O. and Maucher, H. and Kramell, R. and Ziegler, J. and Wasternack, C. and}, title = {{Tissue-specific oxylipin signature of tomato flowers: allene oxide cyclase is highly expressed in distinct flower organs and vascular bundles}}, year = {2000}, pages = {113-126}, journal = {Plant J.}, doi = {10.1046/j.1365-313x.2000.00861.x}, volume = {24}, abstract = {A crucial step in the biosynthesis of jasmonic acid (JA) is the formation of its correct stereoisomeric precursor, cis (\+)12‐oxophytodienoic acid (OPDA). This step is catalysed by allene oxide cyclase (AOC), which has been recently cloned from tomato . In stems, young leaves and young flowers, AOC mRNA accumulates to a low level , contrasting with a high accumulation in flower buds, flower stalks and roots. The high levels of AOC mRNA and AOC protein in distinct flower organs correlate with high AOC activity, and with elevated levels of JA, OPDA and JA isoleucine conjugate. These compounds accumulate in flowers to levels of about 20 nmol g−1 fresh weight, which is two orders of magnitude higher than in leaves. In pistils, the level of OPDA is much higher than that of JA, whereas in flower stalks, the level of JA exceeds that of OPDA. In other flower tissues, the ratios among JA, OPDA and JA isoleucine conjugate differ remarkably, suggesting a tissue‐specific oxylipin signature. Immunocytochemical analysis revealed the specific occurrence of the AOC protein in ovules, the transmission tissue of the style and in vascular bundles of receptacles, flower stalks, stems, petioles and roots. Based on the tissue‐specific AOC expression and formation of JA, OPDA and JA amino acid conjugates, a possible role for these compounds in flower development is discussed in terms of their effect on sink–source relationships and plant defence reactions. Furthermore, the AOC expression in vascular bundles might play a role in the systemin‐mediated wound response of tomato.} } @Article{IPB-2255, author = {Gross, H. B. and Dalebout, T. and Grubb, C. D. and Abel, S. and}, title = {{Functional detection of chemopreventive glucosinolates in Arabidopsis thaliana}}, year = {2000}, pages = {265-272}, journal = {Plant Sci.}, doi = {10.1016/S0168-9452(00)00354-X}, volume = {159}, abstract = {Natural isothiocyanates, derived from glucosinolates by myrosinase-catalyzed hydrolysis, are potent chemopreventive agents that favorably modify carcinogen metabolism in mammals by inhibiting metabolic activation of carcinogens and/or by inducing carcinogen-detoxifying enzymes. Methylsulfinylalkyl isothiocyanates are potent selective inducers of mammalian Phase 2 detoxification enzymes such as quinone reductase [NADP(H):quinone-acceptor oxidoreductase, EC 1.6.99.2]. Members of the Cruciferae family, including the model plant species Arabidopsis thaliana (L.) Heyhn, synthesize methylsulfinylalkyl glucosinolates. We have adapted a colorimetric bioassay for quinone reductase activity in Hepa 1c1c7 murine hepatoma cells as a versatile tool to rapidly monitor methylsulfinylalkyl glucosinolate content in A. thaliana leaf extracts. Using wild type plants and mutant plants defective in the synthesis of 4-methylsulfinylbutyl glucosinolate (glucoraphanin), we have demonstrated that A. thaliana (ecotype Columbia) is a rich source of Phase 2 enzyme inducers and that methylsulfinylalkyl glucosinolates, predominantly glucoraphanin, account for about 80% of the quinone reductase inducer potency of Columbia leaf extracts. We have optimized leaf extraction conditions and the quinone reductase bioassay to allow for screening of large numbers of plant extracts in a molecular genetic approach to dissecting glucosinolate biosynthesis in A. thaliana.} } @Article{IPB-2253, author = {Colón-Carmona, A. and Chen, D. L. and Yeh, K.-C. and Abel, S. and}, title = {{Aux/IAA Proteins Are Phosphorylated by Phytochrome in Vitro}}, year = {2000}, pages = {1728-1738}, journal = {Plant Physiol.}, doi = {10.1104/pp.124.4.1728}, volume = {124}, abstract = {Auxin/indole-3-acetic acid (Aux/IAA) genes encode short-lived transcription factors that are induced as a primary response to the plant growth hormone IAA or auxin. Gain-of-function mutations in Arabidopsis genes,SHY2/IAA3, AXR3/IAA17, andAXR2/IAA7 cause pleiotropic phenotypes consistent with enhanced auxin responses, possibly by increasing Aux/IAA protein stability. Semidominant mutations shy2-1D,shy2-2, axr3-1, and axr2-1induce ectopic light responses in dark-grown seedlings. Because genetic studies suggest that the shy2-1D andshy2-2 mutations bypass phytochrome requirement for certain aspects of photomorphogenesis, we tested whether SHY2/IAA3 and related Aux/IAA proteins interact directly with phytochrome and whether they are substrates for its protein kinase activity. Here we show that recombinant Aux/IAA proteins from Arabidopsis and pea (Pisum sativum) interact in vitro with recombinant phytochrome A from oat (Avena sativa). We further show that recombinant SHY2/IAA3, AXR3/IAA17, IAA1, IAA9, and Ps-IAA4 are phosphorylated by recombinant oat phytochrome A in vitro. Deletion analysis of Ps-IAA4 indicates that phytochrome A phosphorylation occurs on the N-terminal half of the protein. Metabolic labeling and immunoprecipitation studies with affinity-purified antibodies to IAA3 demonstrate increased in vivo steady-state levels of mutant IAA3 in shy2-2 plants and phosphorylation of the SHY2-2 protein in vivo. Phytochrome-dependent phosphorylation of Aux/IAA proteins is proposed to provide one molecular mechanism for integrating auxin and light signaling in plant development.} } @Article{IPB-2252, author = {Chen, D. L. and Delatorre, C. A. and Bakker, A. and Abel, S. and}, title = {{Conditional identification of phosphate-starvation-response mutants in Arabidopsis thaliana}}, year = {2000}, pages = {13-22}, journal = {Planta}, doi = {10.1007/s004250000271}, volume = {211}, abstract = {Plants have evolved elaborate metabolic and developmental adaptations to low phosphorus availability. Biochemical responses to phosphate limitation include increased production and secretion of phosphate-acquisition proteins such as nucleases, acid phosphatases, and high-affinity phosphate transporters. However, the signal transduction pathways that sense phosphate availability and integrate the phosphate-starvation response in plants are unknown. We have devised a screen for conditional mutants in Arabidopsis thaliana (L.) Heynh. to dissect signaling of phosphate limitation. Our genetic screen is based on the facultative ability of wild-type Arabidopsis plants to metabolize exogenous DNA when inorganic phosphate is limiting. After screening 50,000 M2 seedlings, we isolated 22 confirmed mutant lines that showed severely impaired growth on medium containing DNA as the only source of phosphorus, but which recovered on medium containing soluble inorganic phosphate. Characterization of nine such mutant lines demonstrated an inability to utilize either DNA or RNA. One mutant line, psr1 (phosphate starvation response), had significantly reduced activities of phosphate-starvation-inducible isoforms of ribonuclease and acid phosphatase under phosphate-limiting conditions. The data suggest that a subset of the selected mutations impairs the expression of more than one phosphate-starvation-inducible enzyme required for utilization of exogenous nucleic acids, and may thus affect regulatory components of a Pi starvation response pathway in higher plants.} } @Article{IPB-2278, author = {Quint, M. and Melchinger, A. E. and Dußle, C. M. and Lübberstedt, T. and}, title = {{Breeding for virus resistance in maize}}, year = {2000}, pages = {529-545}, journal = {Genetika}, url = {http://www.dgsgenetika.org.rs/abstrakti/vol32_2000_no3_en.htm#Rad26}, volume = {32}, abstract = {Sugarcane mosaic virus (SCMV) is an important disease in maize, which is emerging in Germany since 1983. Using this pest as a model for the inheritance of oligogenic traits, we clarified the genetic ba­sis for resistance in early maturing European maize germplasm. Screening of 122 adapted European inbred lines identified three completely resistant lines, which were used for further analyses. The genetics of SCMV resis­tance was investigated by allelism tests in field experiments combined with QTL and bulked segregant analyses (BSA) on the marker level. QTL analyses revealed the presence of two major genes Scm1 and Scm2 plus three minor QTL. Involvement of Scm1 and Scm2 in the inheritance of SCMV resistance could be confirmed by BSA in a second cross. Breeders can make use of tightly linked STS markers for marker-assisted selection (MAS) as well as our SCMV resistant flint lines to improve their elite germplasm. Currently, recurrent backcrossing with phenotypic selection is the most appropriate and cost effective breeding method. With de­creasing costs of DNA chip technology, MAS can be competitive with phenotypic selection in the near future. Further objectives of our research are the isolation and cloning of Scm1 and Scm2. To achieve this goal we follow two different approaches. (1) Positional cloning based on more than 500 AFLP primer combinations resulted in Scm1/Scm2 specific markers with a resolution of approximately 0.2 cM in the respective re­gions. (2) Resistance gene analogues (RGAs), cosegregating with the tar­get genes are used to identify further candidate genes for transformation experiments.} } @Article{IPB-2473, author = {Hause, B. and zur Nieden, U. and Lehmann, J. and Wasternack, C. and Parthier, B. and}, title = {{Intracellular Localization of Jasmonate-Induced Proteins in Barley Leaves}}, year = {1994}, pages = {333-341}, journal = {Bot. Acta}, doi = {10.1111/j.1438-8677.1994.tb00804.x}, volume = {107}, abstract = {The plant growth substance jasmonic acid and its methyl ester (JA‐Me) induce a set of proteins (jasmonate‐induced proteins, JIPs) when applied to leaf segments of barley (Hordeum vulgare L. cv. Salome). Most of these JIPs could be localized within different cell compartments by using a combination of biochemical and histochemical methods. Isolation and purification of various cell organelles of barley mesophyll cells, the separation of their proteins by one‐dimensional polyacrylamide gel electrophoresis and the identification of the major abundant JIPs by Western blot analysis, as well as the immuno‐gold labelling of JIPs in ultrathin sections were performed to localize JIPs intracellularly. JIP‐23 was found to be in vacuoles, peroxisomes, and in the granular parts of the nucleus as well as within the cytoplasm; JIP‐37 was detected in vacuoles and in the nucleoplasm; JIP‐66 is a cytosolic protein. Some less abundant JIPs were also localized within different cell compartments: JIP‐100 was found within the stromal fraction of chloroplasts; JIP‐70 is present in the peroxisome and the nucleus; JIP‐50 and JIP‐6 accumulate in vacuoles. The location of JIP‐66 and JIP‐6 confirms their possible physiological role deduced from molecular analysis of their cDNA.} } @Article{IPB-2469, author = {Abel, S. and Theologis, A. and}, title = {{Transient transformation of Arabidopsis leaf protoplasts: a versatile experimental system to study gene expression}}, year = {1994}, pages = {421-427}, journal = {Plant J.}, doi = {10.1111/j.1365-313X.1994.00421.x}, volume = {5}, abstract = {An improved protocol is reported to isolate and transiently transform mesophyll protoplasts of Arabidopsis thaliana. Transfected leaf protoplasts support high levels of expression of the bacterial reporter gene coding for β‐glucuronidase (GUS), under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Transient expression of GUS activity was monitored spectrophotometrically and reached a maximum between 18 and 48 h after polyethylene glycol (PEG)‐mediated DNA uptake. Histochemical staining for GUS activity revealed reproducible transformation frequencies between 40 and 60%, based on the number of protoplasts survived. To demonstrate the applicability of the transient expression system, the subcellular localization of GUS proteins tagged with different nuclear polypeptides was studied in transfected mesophyll protoplasts, revealing nuclear compartmentalization of the chimeric GUS enzymes. Furthermore, Arabidopsis mesophyll protoplasts support auxin‐mediated induction of chloramphenicol acetyl‐transferase (CAT) activity when transfected with a transcriptional fusion between the CAT reporter gene and the early auxin‐inducible PS‐IAA4/5 promoter. Hence, the method allows in vivo analysis of promoter activity and subcellular localization of fusion proteins in a homologous transformation system.} } @Article{IPB-2468, author = {Abel, S. and Oeller, P. W. and Theologis, A. and}, title = {{Early auxin-induced genes encode short-lived nuclear proteins.}}, year = {1994}, pages = {326-330}, journal = {Proc. Natl. Acad. Sci. U.S.A.}, doi = {10.1073/pnas.91.1.326}, volume = {91}, abstract = {The plant growth hormone indoleacetic acid (IAA) transcriptionally activates gene expression in plants. Some of the genes whose expression is induced by IAA encode a family of proteins in pea (PS-IAA4 and PS-IAA6) and Arabidopsis (IAA1 and IAA2) that contain putative nuclear localization signals that direct a beta-glucuronidase reporter protein into the nucleus. Pulse-chase and immunoprecipitation experiments have defined the t1/2 of the PS-IAA4 and PS-IAA6 proteins to be 8 and 6 min, respectively. Their most prominent feature is the presence of a beta alpha alpha motif similar to the beta-sheet DNA-binding domain found in prokaryotic repressors of the Arc family. Based on these data, we suggest that plant tissues express short-lived nuclear proteins as a primary response to IAA. We propose that these proteins act as activators or repressors of genes responsible for mediating the various auxin responses.} }