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Publikationen - Molekulare Signalverarbeitung

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Publikation

Wasternack, C.; Termination in Jasmonate Signaling by MYC2 and MTBs Trends Plant Sci. 24, 667-669, (2019) DOI: 10.1016/j.tplants.2019.06.001

Jasmonic acid (JA) signaling can be switched off by metabolism of JA. The master regulator MYC2, interacting with MED25, has been shown to be deactivated by the bHLH transcription factors MTB1, MTB2, and MTB3. An autoregulatory negative feedback loop has been proposed for this termination in JA signaling.
Publikation

Wasternack, C.; New Light on Local and Systemic Wound Signaling Trends Plant Sci. 24, 102-105, (2019) DOI: 10.1016/j.tplants.2018.11.009

Electric signaling and Ca2+ waves were discussed to occur in systemic wound responses. Two new overlapping scenarios were identified: (i) membrane depolarization in two special cell types followed by an increase in systemic cytoplasmic Ca2+ concentration ([Ca2+]cyt), and (ii) glutamate sensed by GLUTAMATE RECEPTOR LIKE proteins and followed by Ca2+-based defense in distal leaves.
Publikation

Wasternack, C.; Hause, B.; A Bypass in Jasmonate Biosynthesis – the OPR3-independent Formation Trends Plant Sci. 23, 276-279, (2018) DOI: 10.1016/j.tplants.2018.02.011

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.
Publikation

Dinesh, D. C.; Calderón Villalobos, L. I. A.; Abel, S.; Structural Biology of Nuclear Auxin Action Trends Plant Sci. 21, 302-316, (2016) DOI: 10.1016/j.tplants.2015.10.019

Auxin coordinates plant development largely via hierarchical control of gene expression. During the past decades, the study of early auxin genes paired with the power of Arabidopsis genetics have unraveled key nuclear components and molecular interactions that perceive the hormone and activate primary response genes. Recent research in the realm of structural biology allowed unprecedented insight into: (i) the recognition of auxin-responsive DNA elements by auxin transcription factors; (ii) the inactivation of those auxin response factors by early auxin-inducible repressors; and (iii) the activation of target genes by auxin-triggered repressor degradation. The biophysical studies reviewed here provide an impetus for elucidating the molecular determinants of the intricate interactions between core components of the nuclear auxin response module.
Publikation

Moss, B. L.; Mao, H.; Guseman, J. M.; Hinds, T. R.; Hellmuth, A.; Kovenock, M.; Noorassa, A.; Lanctot, A.; Calderón Villalobos, L. I. A.; Zheng, N.; Nemhauser, J. L.; Rate Motifs Tune Auxin/Indole-3-Acetic Acid Degradation Dynamics Plant Physiol. 169, 803-813, (2015) DOI: 10.1104/pp.15.00587

Ubiquitin-mediated protein degradation is a common feature in diverse plant cell signaling pathways; however, the factors that control the dynamics of regulated protein turnover are largely unknown. One of the best-characterized families of E3 ubiquitin ligases facilitates ubiquitination of auxin (aux)/indole-3-acetic acid (IAA) repressor proteins in the presence of auxin. Rates of auxin-induced degradation vary widely within the Aux/IAA family, and sequences outside of the characterized degron (the minimum region required for auxin-induced degradation) can accelerate or decelerate degradation. We have used synthetic auxin degradation assays in yeast (Saccharomyces cerevisiae) and in plants to characterize motifs flanking the degron that contribute to tuning the dynamics of Aux/IAA degradation. The presence of these rate motifs is conserved in phylogenetically distant members of the Arabidopsis (Arabidopsis thaliana) Aux/IAA family, as well as in their putative Brassica rapa orthologs. We found that rate motifs can act by enhancing interaction between repressors and the E3, but that this is not the only mechanism of action. Phenotypes of transgenic plants expressing a deletion in a rate motif in IAA28 resembled plants expressing degron mutations, underscoring the functional relevance of Aux/IAA degradation dynamics in regulating auxin responses.
Publikation

Bosch, M.; Wright, L. P.; Gershenzon, J.; Wasternack, C.; Hause, B.; Schaller, A.; Stintzi, A.; Jasmonic Acid and Its Precursor 12-Oxophytodienoic Acid Control Different Aspects of Constitutive and Induced Herbivore Defenses in Tomato Plant Physiol. 166, 396-410, (2014) DOI: 10.1104/pp.114.237388

The jasmonate family of growth regulators includes the isoleucine (Ile) conjugate of jasmonic acid (JA-Ile) and its biosynthetic precursor 12-oxophytodienoic acid (OPDA) as signaling molecules. To assess the relative contribution of JA/JA-Ile and OPDA to insect resistance in tomato (Solanum lycopersicum), we silenced the expression of OPDA reductase3 (OPR3) by RNA interference (RNAi). Consistent with a block in the biosynthetic pathway downstream of OPDA, OPR3-RNAi plants contained wild-type levels of OPDA but failed to accumulate JA or JA-Ile after wounding. JA/JA-Ile deficiency in OPR3-RNAi plants resulted in reduced trichome formation and impaired monoterpene and sesquiterpene production. The loss of these JA/JA-Ile -dependent defense traits rendered them more attractive to the specialist herbivore Manduca sexta with respect to feeding and oviposition. Oviposition preference resulted from reduced levels of repellant monoterpenes and sesquiterpenes. Feeding preference, on the other hand, was caused by increased production of cis-3-hexenal acting as a feeding stimulant for M. sexta larvae in OPR3-RNAi plants. Despite impaired constitutive defenses and increased palatability of OPR3-RNAi leaves, larval development was indistinguishable on OPR3-RNAi and wild-type plants, and was much delayed compared with development on the jasmonic acid-insensitive1 (jai1) mutant. Apparently, signaling through JAI1, the tomato ortholog of the ubiquitin ligase CORONATINE INSENSITIVE1 in Arabidopsis (Arabidopsis thaliana), is required for defense, whereas the conversion of OPDA to JA/JA-Ile is not. Comparing the signaling activities of OPDA and JA/JA-Ile, we found that OPDA can substitute for JA/JA-Ile in the local induction of defense gene expression, but the production of JA/JA-Ile is required for a systemic response.
Publikation

Wasternack, C.; Hause, B.; Blütenduft, Abwehr, Entwicklung: Jasmonsäure - ein universelles Pflanzenhormon Biologie in unserer Zeit 44, 164-171, (2014) DOI: 10.1002/biuz.201410535

Pflanzen müssen gegen vielfältige biotische und abiotische Umwelteinflusse eine Abwehr aufbauen. Aber gleichzeitig müssen sie wachsen und sich vermehren. Jasmonate sind neben anderen Hormonen ein zentrales Signal bei der Etablierung von Abwehrmechanismen, aber auch Signal von Entwicklungsprozessen wie Blüten‐ und Trichombildung, sowie der Hemmung von Wachstum. Biosynthese und essentielle Komponenten der Signaltransduktion von JA und seinem biologisch aktiven Konjugat JA‐Ile sind gut untersucht. Der Rezeptor ist ein Proteinkomplex, der “JA‐Ile‐Wahrnehmung” mit proteasomalem Abbau von Repressorproteinen verbindet. Dadurch können positiv agierende Transkriptionsfaktoren wirksam werden und vielfältige Genexpressionsänderungen auslösen. Dies betrifft die Bildung von Abwehrproteinen, Enzymen der JA‐Biosynthese und Sekundärstoffbildung, und Proteinen von Signalketten und Entwicklungsprozessen. Die Kenntnisse zur JA‐Ile‐Wirkung werden in Landwirtschaft und Biotechnologie genutzt.
Publikation

Goetz, S.; Hellwege, A.; Stenzel, I.; Kutter, C.; Hauptmann, V.; Forner, S.; McCaig, B.; Hause, G.; Miersch, O.; Wasternack, C.; Hause, B.; Role of cis-12-Oxo-Phytodienoic Acid in Tomato Embryo Development Plant Physiol. 158, 1715-1727, (2012) DOI: 10.1104/pp.111.192658

Oxylipins including jasmonates are signaling compounds in plant growth, development, and responses to biotic and abiotic stresses. In Arabidopsis (Arabidopsis thaliana) most mutants affected in jasmonic acid (JA) biosynthesis and signaling are male sterile, whereas the JA-insensitive tomato (Solanum lycopersicum) mutant jai1 is female sterile. The diminished seed formation in jai1 together with the ovule-specific accumulation of the JA biosynthesis enzyme allene oxide cyclase (AOC), which correlates with elevated levels of JAs, suggest a role of oxylipins in tomato flower/seed development. Here, we show that 35S::SlAOC-RNAi lines with strongly reduced AOC in ovules exhibited reduced seed set similarly to the jai1 plants. Investigation of embryo development of wild-type tomato plants showed preferential occurrence of AOC promoter activity and AOC protein accumulation in the developing seed coat and the embryo, whereas 12-oxo-phytodienoic acid (OPDA) was the dominant oxylipin occurring nearly exclusively in the seed coat tissues. The OPDA- and JA-deficient mutant spr2 was delayed in embryo development and showed an increased programmed cell death in the developing seed coat and endosperm. In contrast, the mutant acx1a, which accumulates preferentially OPDA and residual amount of JA, developed embryos similar to the wild type, suggesting a role of OPDA in embryo development. Activity of the residual amount of JA in the acx1a mutant is highly improbable since the known reproductive phenotype of the JA-insensitive mutant jai1 could be rescued by wound-induced formation of OPDA. These data suggest a role of OPDA or an OPDA-related compound for proper embryo development possibly by regulating carbohydrate supply and detoxification.
Publikation

Weigelt, K.; Küster, H.; Rutten, T.; Fait, A.; Fernie, A. R.; Miersch, O.; Wasternack, C.; Emery, R. J. N.; Desel, C.; Hosein, F.; Müller, M.; Saalbach, I.; Weber, H.; ADP-Glucose Pyrophosphorylase-Deficient Pea Embryos Reveal Specific Transcriptional and Metabolic Changes of Carbon-Nitrogen Metabolism and Stress Responses Plant Physiol. 149, 395-411, (2009) DOI: 10.1104/pp.108.129940

We present a comprehensive analysis of ADP-glucose pyrophosphorylase (AGP)-repressed pea (Pisum sativum) seeds using transcript and metabolite profiling to monitor the effects that reduced carbon flow into starch has on carbon-nitrogen metabolism and related pathways. Changed patterns of transcripts and metabolites suggest that AGP repression causes sugar accumulation and stimulates carbohydrate oxidation via glycolysis, tricarboxylic acid cycle, and mitochondrial respiration. Enhanced provision of precursors such as acetyl-coenzyme A and organic acids apparently support other pathways and activate amino acid and storage protein biosynthesis as well as pathways fed by cytosolic acetyl-coenzyme A, such as cysteine biosynthesis and fatty acid elongation/metabolism. As a consequence, the resulting higher nitrogen (N) demand depletes transient N storage pools, specifically asparagine and arginine, and leads to N limitation. Moreover, increased sugar accumulation appears to stimulate cytokinin-mediated cell proliferation pathways. In addition, the deregulation of starch biosynthesis resulted in indirect changes, such as increased mitochondrial metabolism and osmotic stress. The combined effect of these changes is an enhanced generation of reactive oxygen species coupled with an up-regulation of energy-dissipating, reactive oxygen species protection, and defense genes. Transcriptional activation of mitogen-activated protein kinase pathways and oxylipin synthesis indicates an additional activation of stress signaling pathways. AGP-repressed embryos contain higher levels of jasmonate derivatives; however, this increase is preferentially in nonactive forms. The results suggest that, although metabolic/osmotic alterations in iAGP pea seeds result in multiple stress responses, pea seeds have effective mechanisms to circumvent stress signaling under conditions in which excessive stress responses and/or cellular damage could prematurely initiate senescence or apoptosis.
Publikation

Mur, L. A.; Kenton, P.; Atzorn, R.; Miersch, O.; Wasternack, C.; The Outcomes of Concentration-Specific Interactions between Salicylate and Jasmonate Signaling Include Synergy, Antagonism, and Oxidative Stress Leading to Cell Death Plant Physiol. 140, 249-262, (2006) DOI: 10.1104/pp.105.072348

Salicylic acid (SA) has been proposed to antagonize jasmonic acid (JA) biosynthesis and signaling. We report, however, that in salicylate hydroxylase-expressing tobacco (Nicotiana tabacum) plants, where SA levels were reduced, JA levels were not elevated during a hypersensitive response elicited by Pseudomonas syringae pv phaseolicola. The effects of cotreatment with various concentrations of SA and JA were assessed in tobacco and Arabidopsis (Arabidopsis thaliana). These suggested that there was a transient synergistic enhancement in the expression of genes associated with either JA (PDF1.2 [defensin] and Thi1.2 [thionin]) or SA (PR1 [PR1a-β-glucuronidase in tobacco]) signaling when both signals were applied at low (typically 10–100 μm) concentrations. Antagonism was observed at more prolonged treatment times or at higher concentrations. Similar results were also observed when adding the JA precursor, α-linolenic acid with SA. Synergic effects on gene expression and plant stress were NPR1- and COI1-dependent, SA- and JA-signaling components, respectively. Electrolyte leakage and Evans blue staining indicated that application of higher concentrations of SA + JA induced plant stress or death and elicited the generation of apoplastic reactive oxygen species. This was indicated by enhancement of hydrogen peroxide-responsive AoPR10-β-glucuronidase expression, suppression of plant stress/death using catalase, and direct hydrogen peroxide measurements. Our data suggests that the outcomes of JA-SA interactions could be tailored to pathogen/pest attack by the relative concentration of each hormone.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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