TY - JOUR ID - 1359 TI - Jasmonates: biosynthesis, perception, signal transduction and action in plant stress response, growth and development. An update to the 2007 review in Annals of Botany JO - Ann. Bot. PY - 2013 SP - 1021-1058 AU - Wasternack, C. AU - Hause, B. AU - VL - 111 UR - DO - 10.1093/aob/mct067 AB - BackgroundJasmonates are important regulators in plant responses to biotic and abiotic stresses as well as in development. Synthesized from lipid-constituents, the initially formed jasmonic acid is converted to different metabolites including the conjugate with isoleucine. Important new components of jasmonate signalling including its receptor were identified, providing deeper insight into the role of jasmonate signalling pathways in stress responses and development.ScopeThe present review is an update of the review on jasmonates published in this journal in 2007. New data of the last five years are described with emphasis on metabolites of jasmonates, on jasmonate perception and signalling, on cross-talk to other plant hormones and on jasmonate signalling in response to herbivores and pathogens, in symbiotic interactions, in flower development, in root growth and in light perception.ConclusionsThe last few years have seen breakthroughs in the identification of JASMONATE ZIM DOMAIN (JAZ) proteins and their interactors such as transcription factors and co-repressors, and the crystallization of the jasmonate receptor as well as of the enzyme conjugating jasmonate to amino acids. Now, the complex nature of networks of jasmonate signalling in stress responses and development including hormone cross-talk can be addressed. A2 - C1 - Cell and Metabolic Biology; Molecular Signal Processing ER - TY - JOUR ID - 1358 TI - Jasmonates in flower and seed development JO - Biochimie PY - 2013 SP - 79-85 AU - Wasternack, C. AU - Forner, S. AU - Strnad, M. AU - Hause, B. AU - VL - 95 UR - DO - 10.1016/j.biochi.2012.06.005 AB - Jasmonates are ubiquitously occurring lipid-derived signaling compounds active in plant development and plant responses to biotic and abiotic stresses. Upon environmental stimuli jasmonates are formed and accumulate transiently. During flower and seed development, jasmonic acid (JA) and a remarkable number of different metabolites accumulate organ- and tissue specifically. The accumulation is accompanied with expression of jasmonate-inducible genes. Among these genes there are defense genes and developmentally regulated genes. The profile of jasmonate compounds in flowers and seeds covers active signaling molecules such as JA, its precursor 12-oxophytodienoic acid (OPDA) and amino acid conjugates such as JA-Ile, but also inactive signaling molecules occur such as 12-hydroxy-JA and its sulfated derivative. These latter compounds can occur at several orders of magnitude higher level than JA. Metabolic conversion of JA and JA-Ile to hydroxylated compounds seems to inactivate JA signaling, but also specific functions of jasmonates in flower and seed development were detected. In tomato OPDA is involved in embryo development. Occurrence of jasmonates, expression of JA-inducible genes and JA-dependent processes in flower and seed development will be discussed. A2 - C1 - Cell and Metabolic Biology; Molecular Signal Processing ER - TY - JOUR ID - 1337 TI - Optimized Probe Masking for Comparative Transcriptomics of Closely Related Species JO - PLOS ONE PY - 2013 SP - e78497 AU - Poeschl, Y. AU - Delker, C. AU - Trenner, J. AU - Ullrich, K. K. AU - Quint, M. AU - Grosse, I. AU - VL - 8 UR - DO - 10.1371/journal.pone.0078497 AB - Microarrays are commonly applied to study the transcriptome of specific species. However, many available microarrays are restricted to model organisms, and the design of custom microarrays for other species is often not feasible. Hence, transcriptomics approaches of non-model organisms as well as comparative transcriptomics studies among two or more species often make use of cost-intensive RNAseq studies or, alternatively, by hybridizing transcripts of a query species to a microarray of a closely related species. When analyzing these cross-species microarray expression data, differences in the transcriptome of the query species can cause problems, such as the following: (i) lower hybridization accuracy of probes due to mismatches or deletions, (ii) probes binding multiple transcripts of different genes, and (iii) probes binding transcripts of non-orthologous genes. So far, methods for (i) exist, but these neglect (ii) and (iii). Here, we propose an approach for comparative transcriptomics addressing problems (i) to (iii), which retains only transcript-specific probes binding transcripts of orthologous genes. We apply this approach to an Arabidopsis lyrata expression data set measured on a microarray designed for Arabidopsis thaliana, and compare it to two alternative approaches, a sequence-based approach and a genomic DNA hybridization-based approach. We investigate the number of retained probe sets, and we validate the resulting expression responses by qRT-PCR. We find that the proposed approach combines the benefit of sequence-based stringency and accuracy while allowing the expression analysis of much more genes than the alternative sequence-based approach. As an added benefit, the proposed approach requires probes to detect transcripts of orthologous genes only, which provides a superior base for biological interpretation of the measured expression responses. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1333 TI - Plant F-Box Protein Evolution Is Determined by Lineage-Specific Timing of Major Gene Family Expansion Waves JO - PLOS ONE PY - 2013 SP - e68672 AU - Navarro-Quezada, A. AU - Schumann, N. AU - Quint, M. AU - VL - 8 UR - DO - 10.1371/journal.pone.0068672 AB - F-box proteins (FBPs) represent one of the largest and fastest evolving gene/protein families in the plant kingdom. The FBP superfamily can be divided in several subfamilies characterized by different C-terminal protein-protein interaction domains that recruit targets for proteasomal degradation. Hence, a clear picture of their phylogeny and molecular evolution is of special interest for the general understanding of evolutionary histories of multi-domain and/or large protein families in plants. In an effort to further understand the molecular evolution of F-box family proteins, we asked whether the largest subfamily in Arabidopsis thaliana, which carries a C-terminal F-box associated domain (FBA proteins) shares evolutionary patterns and signatures of selection with other FBPs. To address this question, we applied phylogenetic and molecular evolution analyses in combination with the evaluation of transcriptional profiles. Based on the 2219 FBA proteins we de novo identified in 34 completely sequenced plant genomes, we compared their evolutionary patterns to a previously analyzed large subfamily carrying C-terminal kelch repeats. We found that these two large FBP subfamilies generally tend to evolve by massive waves of duplication, followed by sequence conservation of the F-box domain and sequence diversification of the target recruiting domain. We conclude that the earlier in evolutionary time a major wave of expansion occurred, the more pronounced these selection signatures are. As a consequence, when performing cross species comparisons among FBP subfamilies, significant differences will be observed in the selective signatures of protein-protein interaction domains. Depending on the species, the investigated subfamilies comprise up to 45% of the complete superfamily, indicating that other subfamilies possibly follow similar modes of evolution. A2 - C1 - Molecular Signal Processing; Biochemistry of Plant Interactions ER - TY - JOUR ID - 1326 TI - Kinetic analysis of Arabidopsis glucosyltransferase UGT74B1 illustrates a general mechanism by which enzymes can escape product inhibition JO - Biochem. J. PY - 2013 SP - 37-46 AU - Kopycki, J. AU - Wieduwild, E. AU - Kohlschmidt, J. AU - Brandt, W. AU - Stepanova, A. AU - Alonso, J. AU - Pedras, M. S. AU - Abel, S. AU - Grubb, C. D. AU - VL - 450 UR - DO - 10.1042/BJ20121403 AB - Plant genomes encode numerous small molecule glycosyltransferases which modulate the solubility, activity, immunogenicity and/or reactivity of hormones, xenobiotics and natural products. The products of these enzymes can accumulate to very high concentrations, yet somehow avoid inhibiting their own biosynthesis. Glucosyltransferase UGT74B1 (UDP-glycosyltransferase 74B1) catalyses the penultimate step in the core biosynthetic pathway of glucosinolates, a group of natural products with important functions in plant defence against pests and pathogens. We found that mutation of the highly conserved Ser284 to leucine [wei9-1 (weak ethylene insensitive)] caused only very mild morphological and metabolic phenotypes, in dramatic contrast with knockout mutants, indicating that steady state glucosinolate levels are actively regulated even in unchallenged plants. Analysis of the effects of the mutation via a structural modelling approach indicated that the affected serine interacts directly with UDP-glucose, but also predicted alterations in acceptor substrate affinity and the kcat value, sparking an interest in the kinetic behaviour of the wild-type enzyme. Initial velocity and inhibition studies revealed that UGT74B1 is not inhibited by its glycoside product. Together with the effects of the missense mutation, these findings are most consistent with a partial rapid equilibrium ordered mechanism. This model explains the lack of product inhibition observed both in vitro and in vivo, illustrating a general mechanism whereby enzymes can continue to function even at very high product/precursor ratios. A2 - C1 - Bioorganic Chemistry; Molecular Signal Processing ER - TY - JOUR ID - 1318 TI - The eta7/csn3-3 Auxin Response Mutant of Arabidopsis Defines a Novel Function for the CSN3 Subunit of the COP9 Signalosome JO - PLOS ONE PY - 2013 SP - e66578 AU - Huang, H. AU - Quint, M. AU - Gray, W. M. AU - VL - 8 UR - DO - 10.1371/journal.pone.0066578 AB - The COP9 signalosome (CSN) is an eight subunit protein complex conserved in all higher eukaryotes. In Arabidopsis thaliana, the CSN regulates auxin response by removing the ubiquitin-like protein NEDD8/RUB1 from the CUL1 subunit of the SCFTIR1/AFB ubiquitin-ligase (deneddylation). Previously described null mutations in any CSN subunit result in the pleiotropic cop/det/fus phenotype and cause seedling lethality, hampering the study of CSN functions in plant development. In a genetic screen to identify enhancers of the auxin response defects conferred by the tir1-1 mutation, we identified a viable csn mutant of subunit 3 (CSN3), designated eta7/csn3-3. In addition to enhancing tir1-1 mutant phenotypes, the csn3-3 mutation alone confers several phenotypes indicative of impaired auxin signaling including auxin resistant root growth and diminished auxin responsive gene expression. Unexpectedly however, csn3-3 plants are not defective in either the CSN-mediated deneddylation of CUL1 or in SCFTIR1-mediated degradation of Aux/IAA proteins. These findings suggest that csn3-3 is an atypical csn mutant that defines a novel CSN or CSN3-specific function. Consistent with this possibility, we observe dramatic differences in double mutant interactions between csn3-3 and other auxin signaling mutants compared to another weak csn mutant, csn1-10. Lastly, unlike other csn mutants, assembly of the CSN holocomplex is unaffected in csn3-3 plants. However, we detected a small CSN3-containing protein complex that is altered in csn3-3 plants. We hypothesize that in addition to its role in the CSN as a cullin deneddylase, CSN3 functions in a distinct protein complex that is required for proper auxin signaling. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1301 TI - Morphological and biochemical behavior of fenugreek (Trigonella foenum-graecum) under copper stress JO - Ecotoxicol. Environ. Saf. PY - 2013 SP - 46-53 AU - Elleuch, A. AU - Chaâbene, Z. AU - Grubb, D. C. AU - Drira, N. AU - Mejdoub, H. AU - Khemakhem, B. AU - VL - 98 UR - DO - 10.1016/j.ecoenv.2013.09.028 AB - The effects of copper on germination and growth of fenugreek (Trigonella foenum-graecum) was investigated separately using different concentrations of CuSO4. The germination percentage and radical length had different responses to cupric ions: the root growth increased with increasing copper concentration up to 1 mM and Cu2+ was inhibited thereafter. In contrast, the germination percentage was largely unaffected by concentrations of copper below 10 mM.The reduction in root growth may have been due to inhibition of hydrolytic enzymes such as amylase. Indeed, the average total amylolytic activity decreased from the first day of treatment with [Cu2+] greater than 1 mM. Furthermore, copper affected various plant growth parameters. Copper accumulation was markedly higher in roots as compared to shoots. While both showed a gradual decrease in growth, this was more pronounced in roots than in leaves and in stems. Excess copper induced an increase in the rate of hydrogen peroxide (H2O2) production and lipid peroxidation in all plant parts, indicating oxidative stress. This redox stress affected leaf chlorophyll and carotenoid content which decreased in response to augmented Cu levels. Additionally, the activities of proteins involved in reactive oxygen species (ROS) detoxification were affected. Cu stress elevated the ascorbate peroxidase (APX) activity more than two times at 10 mM CuSO4. In contrast, superoxide dismutase (SOD) and catalase (CAT) levels showed only minor variations, only at 1 mM Cu2+. Likewise, total phenol and flavonoid contents were strongly induced by low concentrations of copper, consistent with the role of these potent antioxidants in scavenging ROS such as H2O2, but returned to control levels or below at high [Cu2+]. Taken together, these results indicate a fundamental shift in the plant response to copper toxicity at low versus high concentrations. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1298 TI - Transcriptional Dynamics of Two Seed Compartments with Opposing Roles in Arabidopsis Seed Germination JO - Plant Physiol. PY - 2013 SP - 205-215 AU - Dekkers, B. J. AU - Pearce, S. AU - van Bolderen-Veldkamp, R. AU - Marshall, A. AU - Widera, P. AU - Gilbert, J. AU - Drost, H.-G. AU - Bassel, G. W. AU - Müller, K. AU - King, J. R. AU - Wood, A. T. AU - Grosse, I. AU - Quint, M. AU - Krasnogor, N. AU - Leubner-Metzger, G. AU - Holdsworth, M. J. AU - Bentsink, L. AU - VL - 163 UR - DO - 10.1104/pp.113.223511 AB - Seed germination is a critical stage in the plant life cycle and the first step toward successful plant establishment. Therefore, understanding germination is of important ecological and agronomical relevance. Previous research revealed that different seed compartments (testa, endosperm, and embryo) control germination, but little is known about the underlying spatial and temporal transcriptome changes that lead to seed germination. We analyzed genome-wide expression in germinating Arabidopsis (Arabidopsis thaliana) seeds with both temporal and spatial detail and provide Web-accessible visualizations of the data reported (vseed.nottingham.ac.uk). We show the potential of this high-resolution data set for the construction of meaningful coexpression networks, which provide insight into the genetic control of germination. The data set reveals two transcriptional phases during germination that are separated by testa rupture. The first phase is marked by large transcriptome changes as the seed switches from a dry, quiescent state to a hydrated and active state. At the end of this first transcriptional phase, the number of differentially expressed genes between consecutive time points drops. This increases again at testa rupture, the start of the second transcriptional phase. Transcriptome data indicate a role for mechano-induced signaling at this stage and subsequently highlight the fates of the endosperm and radicle: senescence and growth, respectively. Finally, using a phylotranscriptomic approach, we show that expression levels of evolutionarily young genes drop during the first transcriptional phase and increase during the second phase. Evolutionarily old genes show an opposite pattern, suggesting a more conserved transcriptome prior to the completion of germination. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1295 TI - Arabidopsis Calmodulin-binding Protein IQ67-Domain 1 Localizes to Microtubules and Interacts with Kinesin Light Chain-related Protein-1 JO - J. Biol. Chem. PY - 2013 SP - 1871-1882 AU - Bürstenbinder, K. AU - Savchenko, T. AU - Müller, J. AU - Adamson, A. W. AU - Stamm, G. AU - Kwong, R. AU - Zipp, B. J. AU - Dinesh, D. C. AU - Abel, S. AU - VL - 288 UR - DO - 10.1074/jbc.M112.396200 AB - Calcium (Ca2+) is a key second messenger in eukaryotes and regulates diverse cellular processes, most notably via calmodulin (CaM). In Arabidopsis thaliana, IQD1 (IQ67 domain 1) is the founding member of the IQD family of putative CaM targets. The 33 predicted IQD proteins share a conserved domain of 67 amino acids that is characterized by a unique arrangement of multiple CaM recruitment motifs, including so-called IQ motifs. Whereas IQD1 has been implicated in the regulation of defense metabolism, the biochemical functions of IQD proteins remain to be elucidated. In this study we show that IQD1 binds to multiple Arabidopsis CaM and CaM-like (CML) proteins in vitro and in yeast two-hybrid interaction assays. CaM overlay assays revealed moderate affinity of IQD1 to CaM2 (Kd ∼ 0.6 μm). Deletion mapping of IQD1 demonstrated the importance of the IQ67 domain for CaM2 binding in vitro, which is corroborated by interaction of the shortest IQD member, IQD20, with Arabidopsis CaM/CMLs in yeast. A genetic screen of a cDNA library identified Arabidopsis kinesin light chain-related protein-1 (KLCR1) as an IQD1 interactor. The subcellular localization of GFP-tagged IQD1 proteins to microtubules and the cell nucleus in transiently and stably transformed plant tissues (tobacco leaves and Arabidopsis seedlings) suggests direct interaction of IQD1 and KLCR1 in planta that is supported by GFP∼IQD1-dependent recruitment of RFP∼KLCR1 and RFP∼CaM2 to microtubules. Collectively, the prospect arises that IQD1 and related proteins provide Ca2+/CaM-regulated scaffolds for facilitating cellular transport of specific cargo along microtubular tracks via kinesin motor proteins. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1285 TI - Role of NINJA in root jasmonate signaling JO - Proc. Natl. Acad. Sci. U.S.A. PY - 2013 SP - 15473-15478 AU - Acosta, I. F. AU - Gasperini, D. AU - Chételat, A. AU - Stolz, S. AU - Santuari, L. AU - Farmer, E. E. AU - VL - 110 UR - DO - 10.1073/pnas.1307910110 AB - Wound responses in plants have to be coordinated between organs so that locally reduced growth in a wounded tissue is balanced by appropriate growth elsewhere in the body. We used a JASMONATE ZIM DOMAIN 10 (JAZ10) reporter to screen for mutants affected in the organ-specific activation of jasmonate (JA) signaling in Arabidopsis thaliana seedlings. Wounding one cotyledon activated the reporter in both aerial and root tissues, and this was either disrupted or restricted to certain organs in mutant alleles of core components of the JA pathway including COI1, OPR3, and JAR1. In contrast, three other mutants showed constitutive activation of the reporter in the roots and hypocotyls of unwounded seedlings. All three lines harbored mutations in Novel Interactor of JAZ (NINJA), which encodes part of a repressor complex that negatively regulates JA signaling. These ninja mutants displayed shorter roots mimicking JA-mediated growth inhibition, and this was due to reduced cell elongation. Remarkably, this phenotype and the constitutive JAZ10 expression were still observed in backgrounds lacking the ability to synthesize JA or the key transcriptional activator MYC2. Therefore, JA-like responses can be recapitulated in specific tissues without changing a plant’s ability to make or perceive JA, and MYC2 either has no role or is not the only derepressed transcription factor in ninja mutants. Our results show that the role of NINJA in the root is to repress JA signaling and allow normal cell elongation. Furthermore, the regulation of the JA pathway differs between roots and aerial tissues at all levels, from JA biosynthesis to transcriptional activation. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1284 TI - The emerging function of IQD proteins as scaffolds in cellular signaling and trafficking JO - Plant Signal Behav. PY - 2013 SP - e24369 AU - Abel, S. AU - Bürstenbinder, K. AU - Müller, J. AU - VL - 8 UR - DO - 10.4161/psb.24369 AB - Calcium (Ca2+) signaling modules are essential for adjusting plant growth and performance to environmental constraints. Differential interactions between sensors of Ca2+ dynamics and their molecular targets are at the center of the transduction process. Calmodulin (CaM) and CaM-like (CML) proteins are principal Ca2+-sensors in plants that govern the activities of numerous downstream proteins with regulatory properties. The families of IQ67-Domain (IQD) proteins are a large class of plant-specific CaM/CML-targets (e.g., 33 members in A. thaliana) which share a unique domain of multiple varied CaM retention motifs in tandem orientation. Genetic studies in Arabidopsis and tomato revealed first roles for IQD proteins related to basal defense response and plant development. Molecular, biochemical and histochemical analysis of Arabidopsis IQD1 demonstrated association with microtubules as well as targeting to the cell nucleus and nucleolus. In vivo binding to CaM and kinesin light chain-related protein-1 (KLCR1) suggests a Ca2+-regulated scaffolding function of IQD1 in kinesin motor-dependent transport of multiprotein complexes. Furthermore, because IQD1 interacts in vitro with single-stranded nucleic acids, the prospect arises that IQD1 and other IQD family members facilitate cellular RNA localization as one mechanism to control and fine-tune gene expression and protein sorting. A2 - C1 - Molecular Signal Processing ER - TY - CHAP ID - 85 TI - Benno Parthier und die Jasmonatforschung in Halle T2 - Festkolloquium der Leopoldina anlässlich des 80. Geburtstages von Herrn Altpräsidenten Benno Parthier PB - Nova Acta Leopoldina PY - 2013 SP - 29-38 AU - Wasternack, C. AU - Hause, B. AU - VL - Supplementum Nr. 28 UR - https://www.leopoldina.org/publikationen/detailansicht/publication/festkolloquium-der-leopoldina-anlaesslich-des-80-geburtstages-von-herrn-altpraesidenten-benno-parthie/ AB - A2 - Hacker, J., ed. C1 - Cell and Metabolic Biology; Molecular Signal Processing ER - TY - JOUR ID - 1971 TI - Lack of mycorrhizal autoregulation and phytohormonal changes in the supernodulating soybean mutant nts1007 JO - Planta PY - 2005 SP - 709-715 AU - Meixner, C. AU - Ludwig-Müller, J. AU - Miersch, O. AU - Gresshoff, P. AU - Staehelin, C. AU - Vierheilig, H. AU - VL - 222 UR - DO - 10.1007/s00425-005-0003-4 AB - Autoregulatory mechanisms have been reported in the rhizobial and the mycorrhizal symbiosis. Autoregulation means that already existing nodules or an existing root colonization by an arbuscular mycorrhizal fungus systemically suppress subsequent nodule formation/root colonization in other parts of the root system. Mutants of some legumes lost their ability to autoregulate the nodule number and thus display a supernodulating phenotype. On studying the effect of pre-inoculation of one side of a split-root system with an arbuscular mycorrhizal fungus on subsequent mycorrhization in the second side of the split-root system of a wild-type soybean (Glycine max L.) cv. Bragg and its supernodulating mutant nts1007, we observed a clear suppressional effect in the wild-type, whereas further root colonization in the split-root system of the mutant nts1007 was not suppressed. These data strongly indicate that the mechanisms involved in supernodulation also affect mycorrhization and support the hypothesis that the autoregulation in the rhizobial and the mycorrhizal symbiosis is controlled in a similar manner. The accumulation patterns of the plant hormones IAA, ABA and Jasmonic acid (JA) in non-inoculated control plants and split-root systems of inoculated plants with one mycorrhizal side of the split-root system and one non-mycorrhizal side, indicate an involvement of IAA in the autoregulation of mycorrhization. Mycorrhizal colonization of soybeans also resulted in a strong induction of ABA and JA levels, but on the basis of our data the role of these two phytohormones in mycorrhizal autoregulation is questionable. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1970 TI - Ethylene-mediated cross-talk between calcium-dependent protein kinase and MAPK signaling controls stress responses in plants JO - Proc. Natl. Acad. Sci. U.S.A. PY - 2005 SP - 10736-10741 AU - Ludwig, A. A. AU - Saitoh, H. AU - Felix, G. AU - Freymark, G. AU - Miersch, O. AU - Wasternack, C. AU - Boller, T. AU - Jones, J. D. G. AU - Romeis, T. AU - VL - 102 UR - DO - 10.1073/pnas.0502954102 AB - Plants are constantly exposed to environmental changes and need to integrate multiple external stress cues. Calcium-dependent protein kinases (CDPKs) are implicated as major primary Ca2+ sensors in plants. CDPK activation, like activation of mitogen-activated protein kinases (MAPKs), is triggered by biotic and abiotic stresses, although distinct stimulus-specific stress responses are induced. To investigate whether CDPKs are part of an underlying mechanism to guarantee response specificity, we identified CDPK-controlled signaling pathways. A truncated form of Nicotiana tabacum CDPK2 lacking its regulatory autoinhibitor and calcium-binding domains was ectopically expressed in Nicotiana benthamiana. Infiltrated leaves responded to an abiotic stress stimulus with the activation of biotic stress reactions. These responses included synthesis of reactive oxygen species, defense gene induction, and SGT1-dependent cell death. Furthermore, N-terminal CDPK2 signaling triggered enhanced levels of the phytohormones jasmonic acid, 12-oxo-phytodienoic acid, and ethylene but not salicylic acid. These responses, commonly only observed after challenge with a strong biotic stimulus, were prevented when the CDPK's intrinsic autoinhibitory peptide was coexpressed. Remarkably, elevated CDPK signaling compromised stress-induced MAPK activation, and this inhibition required ethylene synthesis and perception. These data indicate that CDPK and MAPK pathways do not function independently and that a concerted activation of both pathways controls response specificity to biotic and abiotic stress. A2 - C1 - Molecular Signal Processing; Biochemistry of Plant Interactions ER - TY - JOUR ID - 1965 TI - Transient Agrobacterium-mediated gene expression in the Arabidopsis hydroponics root system for subcellular localization studies JO - Plant Mol. Biol. Rep. PY - 2005 SP - 179-184 AU - Levy, M. AU - Rachmilevitch, S. AU - Abel, S. AU - VL - 23 UR - DO - 10.1007/BF02772708 AB - To a great extent, the cellular compartmentalization and molecular interactions are indicative of the function of a protein. The development of simple and efficient tools for testing the subcellular location of proteins is indispensable to elucidate the function of genes in plants. In this report, we assessed the feasibility ofAgrobacterium-mediated transformation of hydroponically grown roots to follow intracellular targeting of proteins fused to green fluorescent protein (GFP). We developed a simple in planta assay for subcellular localization of proteins inArabidopsis roots via transient transformation and tested this method by expressing a GFP fusion of a known nuclear protein, IQD1. Visualization of transiently expressed GFP fusion proteins in roots by means of confocal microscopy is superior to the analysis of green tissues because the roots are virtually transparent and free of chlorophyll autofluorescence. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1964 TI - Arabidopsis IQD1, a novel calmodulin-binding nuclear protein, stimulates glucosinolate accumulation and plant defense JO - Plant J. PY - 2005 SP - 79-96 AU - Levy, M. AU - Wang, Q. AU - Kaspi, R. AU - Parrella, M. P. AU - Abel, S. AU - VL - 43 UR - DO - 10.1111/j.1365-313X.2005.02435.x AB - Glucosinolates are a class of secondary metabolites with important roles in plant defense and human nutrition. To uncover regulatory mechanisms of glucosinolate production, we screened Arabidopsis thaliana T‐DNA activation‐tagged lines and identified a high‐glucosinolate mutant caused by overexpression of IQD1 (At3g09710). A series of gain‐ and loss‐of‐function IQD1 alleles in different accessions correlates with increased and decreased glucosinolate levels, respectively. IQD1 encodes a novel protein that contains putative nuclear localization signals and several motifs known to mediate calmodulin binding, which are arranged in a plant‐specific segment of 67 amino acids, called the IQ67 domain. We demonstrate that an IQD1‐GFP fusion protein is targeted to the cell nucleus and that recombinant IQD1 binds to calmodulin in a Ca2+‐dependent fashion. Analysis of steady‐state messenger RNA levels of glucosinolate pathway genes indicates that IQD1 affects expression of multiple genes with roles in glucosinolate metabolism. Histochemical analysis of tissue‐specific IQD1 ::GUS expression reveals IQD1 promoter activity mainly in vascular tissues of all organs, consistent with the expression patterns of several glucosinolate‐related genes. Interestingly, overexpression of IQD1 reduces insect herbivory, which we demonstrated in dual‐choice assays with the generalist phloem‐feeding green peach aphid (Myzus persicae ), and in weight‐gain assays with the cabbage looper (Trichoplusia ni ), a generalist‐chewing lepidopteran. As IQD1 is induced by mechanical stimuli, we propose IQD1 to be novel nuclear factor that integrates intracellular Ca2+ signals to fine‐tune glucosinolate accumulation in response to biotic challenge. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1959 TI - Suppression of Allene Oxide Cyclase in Hairy Roots of Medicago truncatula Reduces Jasmonate Levels and the Degree of Mycorrhization with Glomus intraradices JO - Plant Physiol. PY - 2005 SP - 1401-1410 AU - Isayenkov, S. AU - Mrosk, C. AU - Stenzel, I. AU - Strack, D. AU - Hause, B. AU - VL - 139 UR - DO - 10.1104/pp.105.069054 AB - During the symbiotic interaction between Medicago truncatula and the arbuscular mycorrhizal (AM) fungus Glomus intraradices, an endogenous increase in jasmonic acid (JA) occurs. Two full-length cDNAs coding for the JA-biosynthetic enzyme allene oxide cyclase (AOC) from M. truncatula, designated as MtAOC1 and MtAOC2, were cloned and characterized. The AOC protein was localized in plastids and found to occur constitutively in all vascular tissues of M. truncatula. In leaves and roots, MtAOCs are expressed upon JA application. Enhanced expression was also observed during mycorrhization with G. intraradices. A partial suppression of MtAOC expression was achieved in roots following transformation with Agrobacterium rhizogenes harboring the MtAOC1 cDNA in the antisense direction under control of the cauliflower mosaic virus 35S promoter. In comparison to samples transformed with 35S∷uidA, roots with suppressed MtAOC1 expression exhibited lower JA levels and a remarkable delay in the process of colonization with G. intraradices. Both the mycorrhization rate, quantified by fungal rRNA, and the arbuscule formation, analyzed by the expression level of the AM-specific gene MtPT4, were affected. Staining of fungal material in roots with suppressed MtAOC1 revealed a decreased number of arbuscules, but these did not exhibit an altered structure. Our results indicate a crucial role for JA in the establishment of AM symbiosis. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER - TY - JOUR ID - 1951 TI - Lipoxygenase-mediated metabolism of storage lipids in germinating sunflower cotyledons and β-oxidation of (9Z,11E,13S)-13-hydroxy-octadeca-9,11-dienoic acid by the cotyledonary glyoxysomes JO - Planta PY - 2005 SP - 919-930 AU - Gerhardt, B. AU - Fischer, K. AU - Balkenhohl, T. J. AU - Pohnert, G. AU - Kühn, H. AU - Wasternack, C. AU - Feussner, I. AU - VL - 220 UR - DO - 10.1007/s00425-004-1408-1 AB - During the early stages of germination, a lipid-body lipoxygenase is expressed in the cotyledons of sunflowers (Helianthus annuus L.). In order to obtain evidence for the in vivo activity of this enzyme during germination, we analyzed the lipoxygenase-dependent metabolism of polyunsaturated fatty acids esterified in the storage lipids. For this purpose, lipid bodies were isolated from etiolated sunflower cotyledons at different stages of germination, and the storage triacylglycerols were analyzed for oxygenated derivatives. During the time course of germination the amount of oxygenated storage lipids was strongly augmented, and we detected triacylglycerols containing one, two or three residues of (9Z,11E,13S)-13-hydro(pero)xy-octadeca-9,11-dienoic acid. Glyoxysomes from etiolated sunflower cotyledons converted (9Z,11E,13S)-13-hydroxy-octadeca-9,11-dienoic acid to (9Z,11E)-13-oxo-octadeca-9,11-dienoic acid via an NADH-dependent dehydrogenase reaction. Both oxygenated fatty acid derivatives were activated to the corresponding CoA esters and subsequently metabolized to compounds of shorter chain length. Cofactor requirement and formation of acetyl-CoA indicate degradation via β-oxidation. However, β-oxidation only proceeded for two consecutive cycles, leading to accumulation of a medium-chain metabolite carrying an oxo group at C-9, equivalent to C-13 of the parent (9Z,11E,13S)-13-hydroxy-octadeca-9,11-dienoic acid. Short-chain β-oxidation intermediates were not detected during incubation. Similar results were obtained when 13-hydroxy octadecanoic acid was used as β-oxidation substrate. On the other hand, the degradation of (9Z,11E)-octadeca-9,11-dienoic acid was accompanied by the appearance of short-chain β-oxidation intermediates in the reaction mixture. The results suggest that the hydroxyl/oxo group at C-13 of lipoxygenase-derived fatty acids forms a barrier to continuous β-oxidation by glyoxysomes. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1950 TI - A kissing-loop interaction in a hammerhead viroid RNA critical for its in vitro folding and in vivo viability JO - RNA PY - 2005 SP - 1073-1083 AU - Gago, S. AU - De la Peña, M. AU - Flores, R. AU - VL - 11 UR - DO - 10.1261/rna.2230605 AB - Chrysanthemum chlorotic mottle viroid (CChMVd) RNA (398–401 nucleotides) can form hammerhead ribozymes that play a functional role in its replication through a rolling-circle mechanism. In contrast to most other viroids, which adopt rod-like or quasi-rod-like secondary structures of minimal free energy, the computer-predicted conformations of CChMVd and Peach latent mosaic viroid (PLMVd) RNAs are branched. Moreover, the covariations found in a number of natural CChMVd variants support that the same or a closely related conformation exists in vivo. Here we report that the CChMVd natural variability also supports that the branched conformation is additionally stabilized by a kissing-loop interaction resembling another one proposed in PLMVd from in vitro assays. Moreover, site-directed mutagenesis combined with bioassays and progeny analysis showed that: (1) single CChMVd mutants affecting the kissing loops had low or no infectivity at all, whereas infectivity was recovered in double mutants restoring the interaction; (2) mutations affecting the structure of the regions adjacent to the kissing loops reverted to wild type or led to rearranged stems, also supporting their interaction; and (3) the interchange between 4 nucleotides of each of the two kissing loops generated a viable CChMVd variant with eight mutations. PAGE analysis under denaturing and nondenaturing conditions revealed that the kissing-loop interaction determines proper in vitro folding of CChMVd RNA. Preservation of a similar kissing-loop interaction in two hammerhead viroids with an overall low sequence similarity suggests that it facilitates in vivo the adoption and stabilization of a compact folding critical for viroid viability. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1948 TI - Expression of Allene Oxide Cyclase and Accumulation of Jasmonates during Organogenic Nodule Formation from Hop (Humulus lupulus var. Nugget) Internodes JO - Plant Cell Physiol. PY - 2005 SP - 1713-1723 AU - Fortes, A. M. AU - Miersch, O. AU - Lange, P. R. AU - Malhó, R. AU - Testillano, P. S. AU - Risueño, M. d. C. AU - Wasternack, C. AU - Pais, M. S. AU - VL - 46 UR - DO - 10.1093/pcp/pci187 AB - A crucial step in the biosynthesis of jasmonic acid (JA) is the formation of its stereoisomeric precursor, cis-(+)-12-oxophytodienoic acid (OPDA), which is catalyzed by allene oxide cyclase (AOC, EC 5.3.99.6). A cDNA of AOC was isolated from Humulus lupulus var. Nugget. The ORF of 765 bp encodes a 255 amino acid protein, which carries a putative chloroplast targeting sequence. The recombinant protein without its putative chloroplast target sequence showed significant AOC activity. Previously we demonstrated that wounding induces organogenic nodule formation in hop. Here we show that the AOC transcript level increases in response to wounding of internodes, peaking between 2 and 4 h after wounding. In addition, Western blot analysis showed elevated levels of AOC peaking 24 h after internode inoculation. The AOC increase was accompanied by increased JA levels 24 h after wounding, whereas OPDA had already reached its highest level after 12 h. AOC is mostly present in the vascular bundles of inoculated internodes. During prenodule and nodule formation, AOC levels were still high. JA and OPDA levels decreased down to 10 and 118 pmol (g FW)–1, respectively, during nodule formation, but increased during plantlet regeneration. Double immunolocalization analysis of AOC and Rubisco in connection with lugol staining showed that AOC is present in amyloplasts of prenodular cells and in the chloroplasts of vacuolated nodular cells, whereas meristematic cells accumulated little AOC. These data suggest a role of AOC and jasmonates in organogenic nodule formation and plantlet regeneration from these nodules. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1944 TI - Animal Models and Analytical Approaches for Understanding the Relationships Between Wine and Cancer JO - Drugs Exp. Clin. Res. PY - 2005 SP - 19-27 AU - Ebeler, S. E. AU - Dingley, K. H. AU - Ubick, E. AU - Abel, S. AU - Mitchell, A. E. AU - Burns, S. A. AU - Steinberg, F. M. AU - Clifford, A. J. AU - VL - 31 UR - https://pubmed.ncbi.nlm.nih.gov/15921026/ AB - We used two approaches for studying the relationships between wine consumption, wine composition and cancer In the first approach, a transgenic mouse model of human neurofibromatosis, combined with the use of well-defined, chemically purified diets, showed that red wine contains nonalcoholic components that can delay tumor onset. In additional studies, catechin, the main monomeric polyphenol of red wine, delayed tumor onset in this mouse model in a positive, linear relationship when incorporated into the diet at levels of 0.5-4 mmol/kg diet. In the second approach, low doses of the chemical carcinogen 2-amino-1-methyl-6-phenylimidazo(4, 5-b)pyridine (PhlP) were administered to rats, and formation of DNA adducts was evaluated by accelerator mass spectrometry. Consumption of red wine solids (the residue from red wine remaining after removal of alcohol and water) and the wine polyphenol quercetin did not influence PhlP-DNA adduct levels or induce liver enzymes (glutathione-S-transferase and quinone reductase). However, quercetin did alter distribution of PhlP in the rat tissues compared to control animals and animals fed other potential dietary chemopreventive agents, including phenylethyl isothiocyanate and sulforaphane. These studies demonstrate the feasibility of these approaches for studying the chemopreventive potential of dietary components at physiologic levels in A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1943 TI - Simultaneous Determination of Multiple Phytohormones in Plant Extracts by Liquid Chromatography−Electrospray Tandem Mass Spectrometry JO - J. Agr. Food Chem. PY - 2005 SP - 8437-8442 AU - Durgbanshi, A. AU - Arbona, V. AU - Pozo, O. AU - Miersch, O. AU - Sancho, J. V. AU - Gómez-Cadenas, A. AU - VL - 53 UR - DO - 10.1021/jf050884b AB - A rapid multiresidue method to quantify three different classes of plant hormones has been developed. The reduced concentrations of these metabolites in real samples with complex matrixes require sensitive techniques for their quantification in small amounts of plant tissue. The method described combines high-performance liquid chromatography with electrospray ionization tandem mass spectrometry. Deuterium-labeled standards were added prior to sample extraction to achieve an accurate quantification of abscisic acid, indole-3-acetic acid, and jasmonic acid in a single run. A simple method of extraction and purification involving only centrifugation, a partition against diethyl ether, and filtration was developed and the analytical method validated in four different plant tissues, citrus leaves, papaya roots, barley seedlings, and barley immature embryos. This method represents a clear advantage because it extensively reduces sample preparation and total time for routine analysis of phytohormones in real plant samples. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1941 TI - Concurrent activation of cell death-regulating signaling pathways by singlet oxygen in Arabidopsis thaliana JO - Plant J. PY - 2005 SP - 68-80 AU - Danon, A. AU - Miersch, O. AU - Felix, G. AU - op den Camp, R. G. L. AU - Apel, K. AU - VL - 41 UR - DO - 10.1111/j.1365-313X.2004.02276.x AB - Upon a dark/light shift the conditional flu mutant of Arabidopsis starts to generate singlet oxygen (1O2), a non‐radical reactive oxygen species that is restricted to the plastid compartment. Immediately after the shift, plants stop growing and develop necrotic lesions. We have established a protoplast system, which allows detection and characterization of the death response in flu induced by the release of 1O2. Vitamin B6 that quenches 1O2 in fungi was able to protect flu protoplasts from cell death. Blocking ethylene production was sufficient to partially inhibit the death reaction. Similarly, flu mutant seedlings expressing transgenic NahG were partially protected from the death provoked by the release of 1O2, indicating a requirement for salicylic acid (SA) in this process, whereas in cells depleted of both, ethylene and SA, the extent of cell death was reduced to the wild‐type level. The flu mutant was also crossed with the jasmonic acid (JA)‐depleted mutant opr3 , and with the JA, OPDA and dinor OPDA (dnOPDA)‐depleted dde2‐2 mutant. Analysis of the resulting double mutants revealed that in contrast to the JA‐induced suppression of H2O2/superoxide‐dependent cell death reported earlier, JA promotes singlet oxygen‐mediated cell death in flu , whereas other oxylipins such as OPDA and dnOPDA antagonize this death‐inducing activity of JA. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1940 TI - Hydroxylated jasmonate levels during stolon to tuber transition in Solarium tuberosum L JO - Potato Res. PY - 2005 SP - 107 AU - Cenzano, A. AU - Vigliocc, A. AU - Miersch, O. AU - Abdala, G. AU - VL - 48 UR - DO - 10.1007/BF02742370 AB - Various octadecanoids and derived compounds have been identified in potato leaves. However, information regarding jasmonate hydroxylated forms in stolons or tubers is scarce. We investigated endogenous jasmonates in stolon material ofSolarium tuberosum cv. Spunta. Stolons and incipient tubers were collected from 8 weeks old plants. The material was cut into apical regions and stolons. We identified jasmonic acid (JA), methyl jasmonate, 11-OH-JA, 12-OH-JA, 12-oxo-phytodienoic acid (OPDA) and a conjugate. The content of JA and 12OH-JA decreased in the apical region but remained high in stolons during tuberization. Thus the apical region might be a site of JAs-utilization or metabolization and stolons might supply JAs to that region. The content of 12-OH-JA was higher than that of 11-OH-JA in all stages analyzed, both in apical regions and stolons. However, these compounds showed a different time-course in the apical region: while 11-OH-JA increased, 12-OH-JA decreased. Thus, JA from leaves or roots could be transported as 12-OH-JA to the apical region, stimulating tuber formation. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1939 TI - The Evolutionarily Conserved TOUGH Protein Is Required for Proper Development of Arabidopsis thaliana JO - Plant Cell PY - 2005 SP - 2473-2485 AU - Calderon-Villalobos, L. I. AU - Kuhnle, C. AU - Dohmann, E. M. AU - Li, H. AU - Bevan, M. AU - Schwechheimer, C. AU - VL - 17 UR - DO - 10.1105/tpc.105.031302 AB - In this study, we characterize the evolutionarily conserved TOUGH (TGH) protein as a novel regulator required for Arabidopsis thaliana development. We initially identified TGH as a yeast two-hybrid system interactor of the transcription initiation factor TATA-box binding protein 2. TGH has apparent orthologs in all eukaryotic model organisms with the exception of the budding yeast Saccharomyces cerevisiae. TGH contains domains with strong similarity to G-patch and SWAP domains, protein domains that are characteristic of RNA binding and processing proteins. Furthermore, TGH colocalizes with the splicing regulator SRp34 to subnuclear particles. We therefore propose that TGH plays a role in RNA binding or processing. Arabidopsis tgh mutants display developmental defects, including reduced plant height, polycotyly, and reduced vascularization. We found TGH expression to be increased in the amp1-1 mutant, which is similar to tgh mutants with respect to polycotyly and defects in vascular development. Interestingly, we observed a strong genetic interaction between TGH and AMP1 in that tgh-1 amp1-1 double mutants are extremely dwarfed and severely affected in plant development in general and vascular development in particular when compared with the single mutants. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1989 TI - Lipid metabolism in arbuscular mycorrhizal roots of Medicago truncatula JO - Phytochemistry PY - 2005 SP - 781-791 AU - Stumpe, M. AU - Carsjens, J.-G. AU - Stenzel, I. AU - Göbel, C. AU - Lang, I. AU - Pawlowski, K. AU - Hause, B. AU - Feussner, I. AU - VL - 66 UR - DO - 10.1016/j.phytochem.2005.01.020 AB - The peroxidation of polyunsaturated fatty acids, common to all eukaryotes, is mostly catalyzed by members of the lipoxygenase enzyme family of non-heme iron containing dioxygenases. Lipoxygenase products can be metabolized further in the oxylipin pathway by several groups of CYP74 enzymes. One prominent oxylipin is jasmonic acid (JA), a product of the 13-allene oxide synthase branch of the pathway and known as signaling substance that plays a role in vegetative and propagative plant development as well as in plant responses to wounding and pathogen attack. In barley roots, JA level increases upon colonization by arbuscular mycorrhizal fungi. Apart from this first result regarding JA, no information is available on the relevance of lipidperoxide metabolism in arbuscular mycorrhizal symbiosis. Thus we analyzed fatty acid and lipidperoxide patterns in roots of Medicago truncatula during mycorrhizal colonization. Levels of fungus-specific fatty acids as well as palmitic acid (16:0) and oleic acid (18:1 n − 9) were increased in mycorrhizal roots. Thus the degree of arbuscular mycorrhizal colonization of roots can be estimated via analysis of fungal specific esterified fatty acids. Otherwise, no significant changes were found in the profiles of esterified and free fatty acids. The 9- and 13-LOX products of linoleic and α-linolenic acid were present in all root samples, but did not show significant differences between mycorrhizal and non-mycorrhizal roots, except JA which showed elevated levels in mycorrhizal roots. In both types of roots levels of 13-LOX products were higher than those of 9-LOX products. In addition, three cDNAs encoding CYP74 enzymes, two 9/13-hydroperoxide lyases and a 13-allene oxide synthase, were isolated and characterized. The transcript accumulation of these three genes, however, was not increased in mycorrhizal roots of M. truncatula. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER - TY - JOUR ID - 1988 TI - Genetic transformation of barley to modify expression of a 13-lipoxygenase JO - Acta Biol. Szeged. PY - 2005 SP - 33-34 AU - Sharma, V. K. AU - Monostori, T. AU - Hause, B. AU - Maucher, H. AU - Göbel, C. AU - Hornung, E. AU - Hänsch, R. AU - Bittner, F. AU - Wasternack, C. AU - Feussner, I. AU - Mendel, R. R. AU - Schulze, J. AU - VL - 49 UR - http://abs.bibl.u-szeged.hu/index.php/abs/article/view/2409 AB - Immature scutella of barley were transformed with cDNA coding for a 13-lipoxygenase of barley (LOX-100) via particle bombardment. Regenerated plants were tested by PAT-assay, Western-analysis and PCR-screening. Immunocytochemical assay of T0 plants showed expression of the LOX cDNA both in the chloroplasts and in the cytosol, depending on the presence of the chloroplast signal peptide sequences in the cDNA. A few transgenic plants containing higher amounts of LOX-derived products have been found. These are the candidates for further analysis concerning pathogen resistance. A2 - C1 - Cell and Metabolic Biology; Molecular Signal Processing ER - TY - JOUR ID - 1987 TI - A New Type of Peroxisomal Acyl-Coenzyme A Synthetase from Arabidopsis thaliana Has the Catalytic Capacity to Activate Biosynthetic Precursors of Jasmonic Acid JO - J. Biol. Chem. PY - 2005 SP - 13962-13972 AU - Schneider, K. AU - Kienow, L. AU - Schmelzer, E. AU - Colby, T. AU - Bartsch, M. AU - Miersch, O. AU - Wasternack, C. AU - Kombrink, E. AU - Stuible, H.-P. AU - VL - 280 UR - DO - 10.1074/jbc.M413578200 AB - Arabidopsis thaliana contains a large number of genes that encode carboxylic acid-activating enzymes, including nine long-chain fatty acyl-CoA synthetases, four 4-coumarate:CoA ligases (4CL), and 25 4CL-like proteins of unknown biochemical function. Because of their high structural and sequence similarity with bona fide 4CLs and their highly hydrophobic putative substrate-binding pockets, the 4CL-like proteins At4g05160 and At5g63380 were selected for detailed analysis. Following heterologous expression, the purified proteins were subjected to a large scale screen to identify their preferred in vitro substrates. This study uncovered a significant activity of At4g05160 with medium-chain fatty acids, medium-chain fatty acids carrying a phenyl substitution, long-chain fatty acids, as well as the jasmonic acid precursors 12-oxo-phytodienoic acid and 3-oxo-2-(2′-pentenyl)-cyclopentane-1-hexanoic acid. The closest homolog of At4g05160, namely At5g63380, showed high activity with long-chain fatty acids and 12-oxo-phytodienoic acid, the latter representing the most efficiently converted substrate. By using fluorescent-tagged variants, we demonstrated that both 4CL-like proteins are targeted to leaf peroxisomes. Collectively, these data demonstrate that At4g05160 and At5g63380 have the capacity to contribute to jasmonic acid biosynthesis by initiating the β-oxidative chain shortening of its precursors. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1984 TI - Changes in jasmonates and 12-oxophytodienoic acid contents of Medicago sativa L. during somatic embryogenesis JO - Acta Physiol. Plant. PY - 2005 SP - 497-504 AU - Rudus, I. AU - Kepczynska, E. AU - Kepczynski, J. AU - Wasternack, C. AU - Miersch, O. AU - VL - 27 UR - DO - 10.1007/s11738-005-0055-x AB - Jasmonic acid (JA), its methyl ester (MeJA) and the biosynthetic precursor 12-oxophytodienoic acid (OPDA) were detected quantitatively during somatic embryogenesis of Medicago sativa L. Using GC-MS analysis, these compounds were found in initial explants, in calli and in somatic embryos in the nanogram range per gram of fresh weight. In distinct stages of somatic embryogenesis, JA and 12-OPDA accumulated preferentially in cotyledonary embryos. Initial explants exhibited about five-fold higher JA content than OPDA content, whereas in other stages OPDA accumulated predominantly. These data suggest that also in embryogenic tissues OPDA and JA may have individual signalling properties. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1982 TI - Characterization of a novel temperature-sensitive allele of the CUL1/AXR6 subunit of SCF ubiquitin-ligases JO - Plant J. PY - 2005 SP - 371-383 AU - Quint, M. AU - Ito, H. AU - Zhang, W. AU - Gray, W. M. AU - VL - 43 UR - DO - 10.1111/j.1365-313X.2005.02449.x AB - Selective protein degradation by the ubiquitin‐proteasome pathway has emerged as a key regulatory mechanism in a wide variety of cellular processes. The selective components of this pathway are the E3 ubiquitin‐ligases which act downstream of the ubiquitin‐activating and ‐conjugating enzymes to identify specific substrates for ubiquitinylation. SCF‐type ubiquitin‐ligases are the most abundant class of E3 enzymes in Arabidopsis. In a genetic screen for enhancers of the tir1‐1 auxin response defect, we identified eta1 /axr6‐3 , a recessive and temperature‐sensitive mutation in the CUL1 core component of the SCFTIR1 complex. The axr6‐3 mutation interferes with Skp1 binding, thus preventing SCF complex assembly. axr6‐3 displays a pleiotropic phenotype with defects in numerous SCF‐regulated pathways including auxin signaling, jasmonate signaling, flower development, and photomorphogenesis. We used axr6‐3 as a tool for identifying pathways likely to be regulated by SCF‐mediated proteolysis and propose new roles for SCF regulation of the far‐red light/phyA and sugar signaling pathways. The recessive inheritance and the temperature‐sensitive nature of the pleiotropically acting axr6‐3 mutation opens promising possibilities for the identification and investigation of SCF‐regulated pathways in Arabidopsis. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1930 TI - Endogenous jasmonates and octadecanoids in hypersensitive tomato mutants during germination and seedling development in response to abiotic stress JO - Seed Sci. Res. PY - 2005 SP - 309-318 AU - Andrade, A. AU - Vigliocco, A. AU - Alemano, S. AU - Miersch, O. AU - Botella, M. A. AU - Abdala, G. AU - VL - 15 UR - DO - 10.1079/SSR2005219 AB - Although jasmonates (JAs) are involved in germination and seedling development, the regulatory mechanism of JAs, and their relation with endogenous level modifications in these processes, is not well understood. We report here the detection of 12-oxo-phytodienoic acid (OPDA), jasmonic acid (JA), 11-hydroxyjasmonate (11-OH-JA), 12-hydroxyjasmonate (12-OH-JA) and methyljasmonate (JAME) in unimbibed seeds and seedlings of tomato Lycopersicon esculentum Mill cv. Moneymaker (wild type) and tss1, tss2, tos1 mutants. The main compounds in wild-type and tss1, tss2, tos1 seeds were the hydroxylate-JAs; 12-OH-JA was the major component in dry seeds of the wild type and in tss2 and tos1. The amounts of these derivatives were higher in seeds than in seedlings. Changes in JAs during wild-type and tss1 imbibition were analysed in seeds and the imbibition water. In wild-type imbibed seeds, 11-OH-JA content was higher than in tss1. 12-OH-JA showed a different tendency with respect to 11-OH-JA, with high levels in the wild type at early imbibition. In tss1, levels of 12-OH-JA rose from 24 to 48 h of imbibition. At 72 h of imbibition, when radicles had emerged, the amounts of both hydroxylates in wild-type and tss1 seeds were minimal. An important release of the hydroxylate forms was observed in the imbibition water. 11-OH-JA decreased in the imbibition water of wild-type seeds at 48 h. On the contrary, a high and sustained liberation of this compound was observed in tss1 after 24 h. 12-OH-JA increased in wild-type as well in tss1 until 24 h. Thereafter, a substantial reduction in the content of this compound was registered. NaCl-treated wild-type seedlings increased their 12-OH-JA, but tss1 seedlings increased their JA in response to salt treatment. In tss2 seedlings, NaCl caused a slight decrease in 11-OH-JA and JAME, whereas tos1 seedlings showed a dramatic OPDA and 12-OH-JA decrease in response to salt treatment. Under salt stress the mutant seedlings showed different patterns of JAs according to their differential hypersensitivity to abiotic stress. The JA-hydroxylate forms found, and the differential accumulation of JAs during germination, imbibition and seedling development, as well as their response to NaCl stress, provide new evidence about the control of many developmental processes by JA. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 1929 TI - Genome-wide comparative analysis of the IQD gene families in Arabidopsis thaliana and Oryza sativa JO - BMC Evol. Biol. PY - 2005 SP - 72 AU - Abel, S. AU - Savchenko, T. AU - Levy, M. AU - VL - 5 UR - DO - 10.1186/1471-2148-5-72 AB - BackgroundCalcium signaling plays a prominent role in plants for coordinating a wide range of developmental processes and responses to environmental cues. Stimulus-specific generation of intracellular calcium transients, decoding of calcium signatures, and transformation of the signal into cellular responses are integral modules of the transduction process. Several hundred proteins with functions in calcium signaling circuits have been identified, and the number of downstream targets of calcium sensors is expected to increase. We previously identified a novel, calmodulin-binding nuclear protein, IQD1, which stimulates glucosinolate accumulation and plant defense in Arabidopsis thaliana. Here, we present a comparative genome-wide analysis of a new class of putative calmodulin target proteins in Arabidopsis and rice.ResultsWe identified and analyzed 33 and 29 IQD1-like genes in Arabidopsis thaliana and Oryza sativa, respectively. The encoded IQD proteins contain a plant-specific domain of 67 conserved amino acid residues, referred to as the IQ67 domain, which is characterized by a unique and repetitive arrangement of three different calmodulin recruitment motifs, known as the IQ, 1-5-10, and 1-8-14 motifs. We demonstrated calmodulin binding for IQD20, the smallest IQD protein in Arabidopsis, which consists of a C-terminal IQ67 domain and a short N-terminal extension. A striking feature of IQD proteins is the high isoelectric point (~10.3) and frequency of serine residues (~11%). We compared the Arabidopsis and rice IQD gene families in terms of gene structure, chromosome location, predicted protein properties and motifs, phylogenetic relationships, and evolutionary history. The existence of an IQD-like gene in bryophytes suggests that IQD proteins are an ancient family of calmodulin-binding proteins and arose during the early evolution of land plants.ConclusionComparative phylogenetic analyses indicate that the major IQD gene lineages originated before the monocot-eudicot divergence. The extant IQD loci in Arabidopsis primarily resulted from segmental duplication and reflect preferential retention of paralogous genes, which is characteristic for proteins with regulatory functions. Interaction of IQD1 and IQD20 with calmodulin and the presence of predicted calmodulin binding sites in all IQD family members suggest that IQD proteins are a new class of calmodulin targets. The basic isoelectric point of IQD proteins and their frequently predicted nuclear localization suggest that IQD proteins link calcium signaling pathways to the regulation of gene expression. Our comparative genomics analysis of IQD genes and encoded proteins in two model plant species provides the first step towards the functional dissection of this emerging family of putative calmodulin targets. A2 - C1 - Molecular Signal Processing ER - TY - CHAP ID - 132 TI - Genus Ophiovirus T2 - Virus Taxonomy PB - PY - 2005 SP - 673-679 AU - Vaira, A. M. AU - Acotto, G. P. AU - Gago-Zachert, S. AU - Garcia, M. L. AU - Grau, O. AU - Milne, R. G. AU - Morikawa, T. AU - Natsuaki, T. AU - Torov, V. AU - Verbeek, M. AU - Vetten, H. J. AU - VL - UR - SN - 9780080575483 DO - 10.1016/B978-0-12-249951-7.50014-6 AB - A2 - C1 - Molecular Signal Processing ER -