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Publikationen - Molekulare Signalverarbeitung

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Publikation

Floková, K.; Feussner, K.; Herrfurth, C.; Miersch, O.; Mik, V.; Tarkowská, D.; Strnad, M.; Feussner, I.; Wasternack, C.; Novák, O.; A previously undescribed jasmonate compound in flowering Arabidopsis thaliana – The identification of cis-(+)-OPDA-Ile Phytochemistry 122, 230-237, (2016) DOI: 10.1016/j.phytochem.2015.11.012

Jasmonates (JAs) are plant hormones that integrate external stress stimuli with physiological responses. (+)-7-iso-JA-L-Ile is the natural JA ligand of COI1, a component of a known JA receptor. The upstream JA biosynthetic precursor cis-(+)-12-oxo-phytodienoic acid (cis-(+)-OPDA) has been reported to act independently of COI1 as an essential signal in several stress-induced and developmental processes. Wound-induced increases in the endogenous levels of JA/JA-Ile are accompanied by two to tenfold increases in the concentration of OPDA, but its means of perception and metabolism are unknown. To screen for putative OPDA metabolites, vegetative tissues of flowering Arabidopsis thaliana were extracted with 25% aqueous methanol (v/v), purified by single-step reversed-phase polymer-based solid-phase extraction, and analyzed by high throughput mass spectrometry. This enabled the detection and quantitation of a low abundant OPDA analog of the biologically active (+)-7-iso-JA-L-Ile in plant tissue samples. Levels of the newly identified compound and the related phytohormones JA, JA-Ile and cis-(+)-OPDA were monitored in wounded leaves of flowering Arabidopsis lines (Col-0 and Ws) and compared to the levels observed in Arabidopsis mutants deficient in the biosynthesis of JA (dde2-2, opr3) and JA-Ile (jar1). The observed cis-(+)-OPDA-Ile levels varied widely, raising questions concerning its role in Arabidopsis stress responses.
Publikation

Arnold, M. D.; Gruber, C.; Floková, K.; Miersch, O.; Strnad, M.; Novák, O.; Wasternack, C.; Hause, B.; The Recently Identified Isoleucine Conjugate of cis-12-Oxo-Phytodienoic Acid Is Partially Active in cis-12-Oxo-Phytodienoic Acid-Specific Gene Expression of Arabidopsis thaliana PLOS ONE 11, e0162829, (2016) DOI: 10.1371/journal.pone.0162829

Oxylipins of the jasmonate family are active as signals in plant responses to biotic and abiotic stresses as well as in development. Jasmonic acid (JA), its precursor cis-12-oxo-phytodienoic acid (OPDA) and the isoleucine conjugate of JA (JA-Ile) are the most prominent members. OPDA and JA-Ile have individual signalling properties in several processes and differ in their pattern of gene expression. JA-Ile, but not OPDA, is perceived by the SCFCOI1-JAZ co-receptor complex. There are, however, numerous processes and genes specifically induced by OPDA. The recently identified OPDA-Ile suggests that OPDA specific responses might be mediated upon formation of OPDA-Ile. Here, we tested OPDA-Ile-induced gene expression in wild type and JA-deficient, JA-insensitive and JA-Ile-deficient mutant background. Tests on putative conversion of OPDA-Ile during treatments revealed only negligible conversion. Expression of two OPDA-inducible genes, GRX480 and ZAT10, by OPDA-Ile could be detected in a JA-independent manner in Arabidopsis seedlings but less in flowering plants. The data suggest a bioactivity in planta of OPDA-Ile.
Publikation

Wasternack, C.; Hause, B.; OPDA-Ile – a new JA-Ile-independent signal? Plant Signal Behav. 11, e1253646, (2016) DOI: 10.1080/15592324.2016.1253646

Expression takes place for most of the jasmonic acid (JA)-induced genes in a COI1-dependent manner via perception of its conjugate JA-Ile in the SCFCOI1-JAZ co-receptor complex. There are, however, numerous genes and processes, which are preferentially induced COI1-independently by the precursor of JA, 12-oxo-phytodienoic acid (OPDA). After recent identification of the Ile-conjugate of OPDA, OPDA-Ile, biological activity of this compound could be unequivocally proven in terms of gene expression. Any interference of OPDA, JA, or JA-Ile in OPDA-Ile-induced gene expression could be excluded by using different genetic background. The data suggest individual signaling properties of OPDA-Ile. Future studies for analysis of an SCFCOI1-JAZ co-receptor-independent route of signaling are proposed.
Publikation

Wasternack, C.; Strnad, M.; Jasmonate signaling in plant stress responses and development – active and inactive compounds New Biotechnol. 33, 604-613, (2016) DOI: 10.1016/j.nbt.2015.11.001

Jasmonates (JAs) are lipid-derived signals mediating plant responses to biotic and abiotic stresses and in plant development. Following the elucidation of each step in their biosynthesis and the important components of perception and signaling, several activators, repressors and co-repressors have been identified which contribute to fine-tuning the regulation of JA-induced gene expression. Many of the metabolic reactions in which JA participates, such as conjugation with amino acids, glucosylation, hydroxylation, carboxylation, sulfation and methylation, lead to numerous compounds with different biological activities. These metabolites may be highly active, partially active in specific processes or inactive. Hydroxylation, carboxylation and sulfation inactivate JA signaling. The precursor of JA biosynthesis, 12-oxo-phytodienoic acid (OPDA), has been identified as a JA-independent signaling compound. An increasing number of OPDA-specific processes is being identified. To conclude, the numerous JA compounds and their different modes of action allow plants to respond specifically and flexibly to alterations in the environment.
Publikation

Otto, M.; Naumann, C.; Brandt, W.; Wasternack, C.; Hause, B.; Activity Regulation by Heteromerization of Arabidopsis Allene Oxide Cyclase Family Members Plants 5, 3, (2016) DOI: 10.3390/plants5010003

Jasmonates (JAs) are lipid-derived signals in plant stress responses and development. A crucial step in JA biosynthesis is catalyzed by allene oxide cyclase (AOC). Four genes encoding functional AOCs (AOC1, AOC2, AOC3 and AOC4) have been characterized for Arabidopsis thaliana in terms of organ- and tissue-specific expression, mutant phenotypes, promoter activities and initial in vivo protein interaction studies suggesting functional redundancy and diversification, including first hints at enzyme activity control by protein-protein interaction. Here, these analyses were extended by detailed analysis of recombinant proteins produced in Escherichia coli. Treatment of purified AOC2 with SDS at different temperatures, chemical cross-linking experiments and protein structure analysis by molecular modelling approaches were performed. Several salt bridges between monomers and a hydrophobic core within the AOC2 trimer were identified and functionally proven by site-directed mutagenesis. The data obtained showed that AOC2 acts as a trimer. Finally, AOC activity was determined in heteromers formed by pairwise combinations of the four AOC isoforms. The highest activities were found for heteromers containing AOC4 + AOC1 and AOC4 + AOC2, respectively. All data are in line with an enzyme activity control of all four AOCs by heteromerization, thereby supporting a putative fine-tuning in JA formation by various regulatory principles.
Bücher und Buchkapitel

Wasternack, C.; Jasmonates: Synthesis, Metabolism, Signal Transduction and Action (2016) DOI: 10.1002/9780470015902.a0020138.pub2

Jasmonic acid and other fatty‐acid‐derived compounds called oxylipins are signals in stress responses and development of plants. The receptor complex, signal transduction components as well as repressors and activators in jasmonate‐induced gene expression have been elucidated. Different regulatory levels and cross‐talk with other hormones are responsible for the multiplicity of plant responses to environmental and developmental cues.
Publikation

Floková, K.; Tarkowská, D.; Miersch, O.; Strnad, M.; Wasternack, C.; Novák, O.; UHPLC–MS/MS based target profiling of stress-induced phytohormones Phytochemistry 105, 147-157, (2014) DOI: 10.1016/j.phytochem.2014.05.015

Stress-induced changes in phytohormone metabolite profiles have rapid effects on plant metabolic activity and growth. The jasmonates (JAs) are a group of fatty acid-derived stress response regulators with roles in numerous developmental processes. To elucidate their dual regulatory effects, which overlap with those of other important defence-signalling plant hormones such as salicylic acid (SA), abscisic acid (ABA) and indole-3-acetic acid (IAA), we have developed a highly efficient single-step clean-up procedure for their enrichment from complex plant matrices that enables their sensitive quantitative analysis using hyphenated mass spectrometry technique. The rapid extraction of minute quantities of plant material (less than 20 mg fresh weight, FW) into cold 10% methanol followed by one-step reversed-phase polymer-based solid phase extraction significantly reduced matrix effects and increased the recovery of labile JA analytes. This extraction and purification protocol was paired with a highly sensitive and validated ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) method and used to simultaneously profile sixteen stress-induced phytohormones in minute plant material samples, including endogenous JA, several of its biosynthetic precursors and derivatives, as well as SA, ABA and IAA.
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.; Perception, signaling and cross-talk of jasmonates and the seminal contributions of the Daoxin Xie’s lab and the Chuanyou Li’s lab Plant Cell Rep. 33, 707-718, (2014) DOI: 10.1007/s00299-014-1608-5

Jasmonates (JAs) are lipid-derived signals in plant responses to biotic and abiotic stresses and in development. The most active JA compound is (+)-7-iso-JA-Ile, a JA conjugate with isoleucine. Biosynthesis, metabolism and key components of perception and signal transduction have been identified and numerous JA-induced gene expression data collected. For JA-Ile perception, the SCFCOI1–JAZ co-receptor complex has been identified and crystalized. Activators such as MYC2 and repressors such as JAZs including their targets were found. Involvement of JA-Ile in response to herbivores and pathogens and in root growth inhibition is among the most studied aspects of JA-Ile signaling. There are an increasing number of examples, where JA-Ile shows cross-talk with other plant hormones. Seminal contributions in JA/JA-Ile research were given by Daoxin Xie’s lab and Chuanyou Li’s lab, both in Beijing. Here, characterization was done regarding components of the JA-Ile receptor, such as COI1 (JAI1) and SCF, regarding activators (MYCs, MYBs) and repressors (JAV1, bHLH IIId’s) of JA-regulated gene expression, as well as regarding components of auxin biosynthesis and action, such as the transcription factor PLETHORA active in the root stem cell niche. This overview reflects the work of both labs in the light of our present knowledge on biosynthesis, perception and signal transduction of JA/JA-Ile and its cross-talk to other hormones.
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.
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