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Publikationen - Molekulare Signalverarbeitung

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Publikation

Dekkers, B. J.; Pearce, S.; van Bolderen-Veldkamp, R.; Marshall, A.; Widera, P.; Gilbert, J.; Drost, H.-G.; Bassel, G. W.; Müller, K.; King, J. R.; Wood, A. T.; Grosse, I.; Quint, M.; Krasnogor, N.; Leubner-Metzger, G.; Holdsworth, M. J.; Bentsink, L.; Transcriptional Dynamics of Two Seed Compartments with Opposing Roles in Arabidopsis Seed Germination Plant Physiol. 163, 205-215, (2013) DOI: 10.1104/pp.113.223511

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.
Publikation

Acosta, I. F.; Gasperini, D.; Chételat, A.; Stolz, S.; Santuari, L.; Farmer, E. E.; Role of NINJA in root jasmonate signaling Proc. Natl. Acad. Sci. U.S.A. 110, 15473-15478, (2013) DOI: 10.1073/pnas.1307910110

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.
Publikation

Wasternack, C.; Forner, S.; Strnad, M.; Hause, B.; Jasmonates in flower and seed development Biochimie 95, 79-85, (2013) DOI: 10.1016/j.biochi.2012.06.005

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.
Publikation

Wasternack, C.; Hause, B.; Jasmonates: biosynthesis, perception, signal transduction and action in plant stress response, growth and development. An update to the 2007 review in Annals of Botany Ann. Bot. 111, 1021-1058, (2013) DOI: 10.1093/aob/mct067

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.
Bücher und Buchkapitel

Wasternack, C.; Hause, B.; Benno Parthier und die Jasmonatforschung in Halle (Hacker, J., ed.). Nova Acta Leopoldina Supplementum Nr. 28, 29-38, (2013)

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Publikation

Schilling, S.; Stenzel, I.; von Bohlen, A.; Wermann, M.; Schulz, K.; Demuth, H.-U.; Wasternack, C.; Isolation and characterization of the glutaminyl cyclases from Solanum tuberosum and Arabidopsis thaliana: implications for physiological functions Biol. Chem. 388, 145-153, (2007) DOI: 10.1515/BC.2007.016

Glutaminyl cyclases (QCs) catalyze the formation of pyroglutamic acid at the N-terminus of several peptides and proteins. On the basis of the amino acid sequence of Carica papaya QC, we identified cDNAs of the putative counterparts from Solanum tuberosum and Arabidopsis thaliana. Upon expression of the corresponding cDNAs from both plants via the secretory pathway of Pichia pastoris, two active QC proteins were isolated. The specificity of the purified proteins was assessed using various substrates with different amino acid composition and length. Highest specificities were observed with substrates possessing large hydrophobic residues adjacent to the N-terminal glutamine and for fluorogenic dipeptide surrogates. However, compared to Carica papaya QC, the specificity constants were approximately one order of magnitude lower for most of the QC substrates analyzed. The QCs also catalyzed the conversion of N-terminal glutamic acid to pyroglutamic acid, but with approximately 105- to 106-fold lower specificity. The ubiquitous distribution of plant QCs prompted a search for potential substrates in plants. Based on database entries, numerous proteins, e.g., pathogenesis-related proteins, were found that carry a pyroglutamate residue at the N-terminus, suggesting QC involvement. The putative relevance of QCs and pyroglutamic acid for plant defense reactions is discussed.
Publikation

Lannoo, N.; Vandenborre, G.; Miersch, O.; Smagghe, G.; Wasternack, C.; Peumans, W. J.; Van Damme, E. J. M.; The Jasmonate-Induced Expression of the Nicotiana tabacum Leaf Lectin Plant Cell Physiol. 48, 1207-1218, (2007) DOI: 10.1093/pcp/pcm090

Previous experiments with tobacco (Nicotiana tabacum L. cv Samsun NN) plants revealed that jasmonic acid methyl ester (JAME) induces the expression of a cytoplasmic/nuclear lectin in leaf cells and provided the first evidence that jasmonates affect the expression of carbohydrate-binding proteins in plant cells. To corroborate the induced accumulation of relatively large amounts of a cytoplasmic/nuclear lectin, a detailed study was performed on the induction of the lectin in both intact tobacco plants and excised leaves. Experiments with different stress factors demonstrated that the lectin is exclusively induced by exogeneously applied jasmonic acid and JAME, and to a lesser extent by insect herbivory. The lectin concentration depends on leaf age and the position of the tissue in the leaf. JAME acts systemically in intact plants but very locally in excised leaves. Kinetic analyses indicated that the lectin is synthesized within 12 h exposure time to JAME, reaching a maximum after 60 h. After removal of JAME, the lectin progressively disappears from the leaf tissue. The JAME-induced accumulation of an abundant nuclear/cytoplasmic lectin is discussed in view of the possible role of this lectin in the plant.
Publikation

Guranowski, A.; Miersch, O.; Staswick, P. E.; Suza, W.; Wasternack, C.; Substrate specificity and products of side-reactions catalyzed by jasmonate:amino acid synthetase (JAR1) FEBS Lett. 581, 815-820, (2007) DOI: 10.1016/j.febslet.2007.01.049

Jasmonate:amino acid synthetase (JAR1) is involved in the function of jasmonic acid (JA) as a plant hormone. It catalyzes the synthesis of several JA‐amido conjugates, the most important of which appears to be JA‐Ile. Structurally, JAR1 is a member of the firefly luciferase superfamily that comprises enzymes that adenylate various organic acids. This study analyzed the substrate specificity of recombinant JAR1 and determined whether it catalyzes the synthesis of mono‐ and dinucleoside polyphosphates, which are side‐reaction products of many enzymes forming acyl ∼ adenylates. Among different oxylipins tested as mixed stereoisomers for substrate activity with JAR1, the highest rate of conversion to Ile‐conjugates was observed for (±)‐JA and 9,10‐dihydro‐JA, while the rate of conjugation with 12‐hydroxy‐JA and OPC‐4 (3‐oxo‐2‐(2Z ‐pentenyl)cyclopentane‐1‐butyric acid) was only about 1–2% that for (±)‐JA. Of the two stereoisomers of JA, (−)‐JA and (+)‐JA, rate of synthesis of the former was about 100‐fold faster than for (+)‐JA. Finally, we have demonstrated that (1) in the presence of ATP, Mg2+, (−)‐JA and tripolyphosphate the ligase produces adenosine 5′‐tetraphosphate (p4A); (2) addition of isoleucine to that mixture halts the p4A synthesis; (3) the enzyme produces neither diadenosine triphosphate (Ap3A) nor diadenosine tetraphosphate (Ap4A) and (4) Ap4A cannot substitute ATP as a source of adenylate in the complete reaction that yields JA‐Ile.
Publikation

Wasternack, C.; Jasmonates: An Update on Biosynthesis, Signal Transduction and Action in Plant Stress Response, Growth and Development Ann. Bot. 100, 681-697, (2007) DOI: 10.1093/aob/mcm079

BackgroundJasmonates are ubiquitously occurring lipid-derived compounds with signal functions in plant responses to abiotic and biotic stresses, as well as in plant growth and development. Jasmonic acid and its various metabolites are members of the oxylipin family. Many of them alter gene expression positively or negatively in a regulatory network with synergistic and antagonistic effects in relation to other plant hormones such as salicylate, auxin, ethylene and abscisic acid.ScopeThis review summarizes biosynthesis and signal transduction of jasmonates with emphasis on new findings in relation to enzymes, their crystal structure, new compounds detected in the oxylipin and jasmonate families, and newly found functions.ConclusionsCrystal structure of enzymes in jasmonate biosynthesis, increasing number of jasmonate metabolites and newly identified components of the jasmonate signal-transduction pathway, including specifically acting transcription factors, have led to new insights into jasmonate action, but its receptor(s) is/are still missing, in contrast to all other plant hormones.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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