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Publikation

Wasternack, C.; Xie, D.; The genuine ligand of a jasmonic acid receptor: Improved analysis of jasmonates is now required Plant Signal Behav. 5, 337-340, (2010) DOI: 10.4161/psb.5.4.11574

Jasmonic acid (JA), its metabolites, such as the methyl ester or amino acid conjugates as well as its precursor 12-oxophytodienoic acid (OPDA) are lipid-derived signals. JA, OPDA and JA-amino acid conjugates are known to function as signals in plant stress responses and development. More recently, formation of JA-amino acid conjugates and high biological activity of JA-Isoleucine (JA-Ile) were found to be essential in JA signalling. A breakthrough was the identification of JAZ proteins which interact with the F-box protein COI1 if JA-Ile is bound. This interaction leads to proteasomal degradation of JAZs being negative regulators of JA-induced transcription. Surprisingly, a distinct stereoisomer of JA-Ile, the (+)-7-iso-JA-Ile ((3R,7S) form) is most active. Coronatine, a bacterial phytotoxine with an identical stereochemistry at the cyclopentanone ring, has a similar bioactivity . This was explained by the recent identification of COI1 as the JA receptor and accords well with molecular modelling studies. Whereas over the last two decades JA was quantified to describe any JA dependent process, now we have to take into account a distinct stereoisomer of JA-Ile. Until recently a quantitative analysis of (+)-7-iso-JA-Ile was missing presumable due to its equilibration to (-)-JA-Ile. Now such an analysis was achieved. These aspects will be discussed based on our new knowledge on JA perception and signalling.
Publikation

Wasternack, C.; Kombrink, E.; Jasmonates: Structural Requirements for Lipid-Derived Signals Active in Plant Stress Responses and Development ACS Chem. Biol. 5, 63-77, (2010) DOI: 10.1021/cb900269u

Jasmonates are lipid-derived signals that mediate plant stress responses and development processes. Enzymes participating in biosynthesis of jasmonic acid (JA) (1, 2) and components of JA signaling have been extensively characterized by biochemical and molecular-genetic tools. Mutants of Arabidopsis and tomato have helped to define the pathway for synthesis of jasmonoyl-isoleucine (JA-Ile), the active form of JA, and to identify the F-box protein COI1 as central regulatory unit. However, details of the molecular mechanism of JA signaling have only recently been unraveled by the discovery of JAZ proteins that function in transcriptional repression. The emerging picture of JA perception and signaling cascade implies the SCFCOI1 complex operating as E3 ubiquitin ligase that upon binding of JA-Ile targets JAZ repressors for degradation by the 26S-proteasome pathway, thereby allowing the transcription factor MYC2 to activate gene expression. The fact that only one particular stereoisomer, (+)-7-iso-JA-l-Ile (4), shows high biological activity suggests that epimerization between active and inactive diastereomers could be a mechanism for turning JA signaling on or off. The recent demonstration that COI1 directly binds (+)-7-iso-JA-l-Ile (4) and thus functions as JA receptor revealed that formation of the ternary complex COI1-JA-Ile-JAZ is an ordered process. The pronounced differences in biological activity of JA stereoisomers also imply strict stereospecific control of product formation along the JA biosynthetic pathway. The pathway of JA biosynthesis has been unraveled, and most of the participating enzymes are well-characterized. For key enzymes of JA biosynthesis the crystal structures have been established, allowing insight into the mechanisms of catalysis and modes of substrate binding that lead to formation of stereospecific products.
Publikation

Stumpe, M.; Göbel, C.; Faltin, B.; Beike, A. K.; Hause, B.; Himmelsbach, K.; Bode, J.; Kramell, R.; Wasternack, C.; Frank, W.; Reski, R.; Feussner, I.; The moss Physcomitrella patens contains cyclopentenones but no jasmonates: mutations in allene oxide cyclase lead to reduced fertility and altered sporophyte morphology New Phytol. 188, 740-749, (2010) DOI: 10.1111/j.1469-8137.2010.03406.x

Two cDNAs encoding allene oxide cyclases (PpAOC1, PpAOC2), key enzymes in the formation of jasmonic acid (JA) and its precursor (9S,13S)‐12‐oxo‐phytodienoic acid (cis‐(+)‐OPDA), were isolated from the moss Physcomitrella patens.Recombinant PpAOC1 and PpAOC2 show substrate specificity against the allene oxide derived from 13‐hydroperoxy linolenic acid (13‐HPOTE); PpAOC2 also shows substrate specificity against the allene oxide derived from 12‐hydroperoxy arachidonic acid (12‐HPETE).In protonema and gametophores the occurrence of cis‐(+)‐OPDA, but neither JA nor the isoleucine conjugate of JA nor that of cis‐(+)‐OPDA was detected.Targeted knockout mutants for PpAOC1 and for PpAOC2 were generated, while double mutants could not be obtained. The ΔPpAOC1 and ΔPpAOC2 mutants showed reduced fertility, aberrant sporophyte morphology and interrupted sporogenesis.
Publikation

Robson, F.; Okamoto, H.; Patrick, E.; Harris, S.-R.; Wasternack, C.; Brearley, C.; Turner, J. G.; Jasmonate and Phytochrome A Signaling in Arabidopsis Wound and Shade Responses Are Integrated through JAZ1 Stability Plant Cell 22, 1143-1160, (2010) DOI: 10.1105/tpc.109.067728

Jasmonate (JA) activates plant defense, promotes pollen maturation, and suppresses plant growth. An emerging theme in JA biology is its involvement in light responses; here, we examine the interdependence of the JA- and light-signaling pathways in Arabidopsis thaliana. We demonstrate that mutants deficient in JA biosynthesis and signaling are deficient in a subset of high irradiance responses in far-red (FR) light. These mutants display exaggerated shade responses to low, but not high, R/FR ratio light, suggesting a role for JA in phytochrome A (phyA) signaling. Additionally, we demonstrate that the FR light–induced expression of transcription factor genes is dependent on CORONATINE INSENSITIVE1 (COI1), a central component of JA signaling, and is suppressed by JA. phyA mutants had reduced JA-regulated growth inhibition and VSP expression and increased content of cis-(+)-12-oxophytodienoic acid, an intermediate in JA biosynthesis. Significantly, COI1-mediated degradation of JASMONATE ZIM DOMAIN1-β-glucuronidase (JAZ1-GUS) in response to mechanical wounding and JA treatment required phyA, and ectopic expression of JAZ1-GUS resulted in exaggerated shade responses. Together, these results indicate that JA and phyA signaling are integrated through degradation of the JAZ1 protein, and both are required for plant responses to light and stress.
Publikation

Leon-Reyes, A.; Van der Does, D.; De Lange, E. S.; Delker, C.; Wasternack, C.; Van Wees, S. C. M.; Ritsema, T.; Pieterse, C. M. J.; Salicylate-mediated suppression of jasmonate-responsive gene expression in Arabidopsis is targeted downstream of the jasmonate biosynthesis pathway Planta 232, 1423-1432, (2010) DOI: 10.1007/s00425-010-1265-z

Jasmonates (JAs) and salicylic acid (SA) are plant hormones that play pivotal roles in the regulation of induced defenses against microbial pathogens and insect herbivores. Their signaling pathways cross-communicate providing the plant with a regulatory potential to finely tune its defense response to the attacker(s) encountered. In Arabidopsis thaliana, SA strongly antagonizes the jasmonic acid (JA) signaling pathway, resulting in the downregulation of a large set of JA-responsive genes, including the marker genes PDF1.2 and VSP2. Induction of JA-responsive marker gene expression by different JA derivatives was equally sensitive to SA-mediated suppression. Activation of genes encoding key enzymes in the JA biosynthesis pathway, such as LOX2, AOS, AOC2, and OPR3 was also repressed by SA, suggesting that the JA biosynthesis pathway may be a target for SA-mediated antagonism. To test this, we made use of the mutant aos/dde2, which is completely blocked in its ability to produce JAs because of a mutation in the ALLENE OXIDE SYNTHASE gene. Mutant aos/dde2 plants did not express the JA-responsive marker genes PDF1.2 or VSP2 in response to infection with the necrotrophic fungus Alternaria brassicicola or the herbivorous insect Pieris rapae. Bypassing JA biosynthesis by exogenous application of methyl jasmonate (MeJA) rescued this JA-responsive phenotype in aos/dde2. Application of SA suppressed MeJA-induced PDF1.2 expression to the same level in the aos/dde2 mutant as in wild-type Col-0 plants, indicating that SA-mediated suppression of JA-responsive gene expression is targeted at a position downstream of the JA biosynthesis pathway.
Bücher und Buchkapitel

Wasternack, C.; Jasmonates in Stress, Growth, and Development 91-118, (2010) ISBN: 9783527628964 DOI: 10.1002/9783527628964.ch5

This chapter contains sections titled:IntroductionJA BiosynthesisJA MetabolismBound OPDA – ArabidopsidesMutants of JA Biosynthesis and SignalingCOI1–JAZ–JA‐Ile‐Mediated JA SignalingTranscription Factors Involved in JA SignalingJasmonates and Oxylipins in DevelopmentConclusionsAcknowledgmentsReferences
Publikation

Kenton, P.; Mur, L. A. J.; Atzorn, R.; Wasternack, C.; Draper, J.; (—)-Jasmonic Acid Accumulation in Tobacco Hypersensitive Response Lesions Mol. Plant Microbe Interact. 12, 74-78, (1999) DOI: 10.1094/MPMI.1999.12.1.74

Tobacco infected with Pseudomonas syringae pv. phaseolicola undergoes a hypersensitive response (HR). Jasmonic acid (JA) accumulated within the developing lesion 3 to 9 h after infection and this accumulation preceded protein loss, cell death, and malondialdehyde accumulation. Accumulating JA consisted largely of the (—)-JA stereoisomer and was essentially restricted to the HR lesion.
Publikation

Herde, O.; Peña Cortés, H.; Wasternack, C.; Willmitzer, L.; Fisahn, J.; Electric Signaling and Pin2 Gene Expression on Different Abiotic Stimuli Depend on a Distinct Threshold Level of Endogenous Abscisic Acid in Several Abscisic Acid-Deficient Tomato Mutants Plant Physiol. 119, 213-218, (1999) DOI: 10.1104/pp.119.1.213

Experiments were performed on three abscisic acid (ABA)-deficient tomato (Lycopersicon esculentum Mill.) mutants, notabilis,flacca, and sitiens, to investigate the role of ABA and jasmonic acid (JA) in the generation of electrical signals and Pin2 (proteinaseinhibitor II) gene expression. We selected these mutants because they contain different levels of endogenous ABA. ABA levels in the mutant sitiens were reduced to 8% of the wild type, in notabilis they were reduced to 47%, and in flacca they were reduced to 21%. In wild-type and notabilis tomato plants the induction ofPin2 gene expression could be elicited by heat treatment, current application, or mechanical wounding. Inflacca and sitiens only heat stimulation induced Pin2 gene expression. JA levels inflacca and sitiens plants also accumulated strongly upon heat stimulation but not upon mechanical wounding or current application. Characteristic electrical signals evolved in the wild type and in the notabilis andflacca mutants consisting of a fast action potential and a slow variation potential. However, in sitiens only heat evoked electrical signals; mechanical wounding and current application did not change the membrane potential. In addition, exogenous application of ABA to wild-type tomato plants induced transient changes in membrane potentials, indicating the involvement of ABA in the generation of electrical signals. Our data strongly suggest the presence of a minimum threshold value of ABA within the plant that is essential for the early events in electrical signaling and mediation of Pin2 gene expression upon wounding. In contrast, heat-induced Pin2 gene expression and membrane potential changes were not dependent on the ABA level but, rather, on the accumulation of JA.
Publikation

Hause, B.; Hertel, S. C.; Klaus, D.; Wasternack, C.; Cultivar-Specific Expression of the Jasmonate-Induced Protein of 23 kDa (JIP-23) Occurs in Hordeum vulgare L. by Jasmonates but not During Seed Germination Plant Biol. 1, 83-89, (1999) DOI: 10.1111/j.1438-8677.1999.tb00712.x

Treatment of barley leaf segments with jasmonic acid methyl ester (JM) leads to the accumulation of a set of newly formed abundant proteins. Among them, the most abun dant protein exhibits a molecular mass of 23 kDa (JIP‐23). Here, data are presented on the occurrence and expression of the lIP‐23 genes in different cultivars of Hordeum vulgare . Southern blot analysis of 80 cultivars revealed the occurrence of 2 to 4 genes coding for JIP‐23 in all cultivars. By means of Northern blot and immunoblot analysis it is shown that some cultivars lack the ex pression of jip‐23 upon treatment of primary leaves with JM as well as upon stress performed by incubation with 1 M sorbitol solution. During germination, however, all tested cultivars ex hibited developmental expression of jip‐23 . The results are dis cussed in terms of possible functions of JIP‐23 in barley.
Publikation

Hause, B.; Vörös, K.; Kogel, K.-H.; Besser, K.; Wasternack, C.; A Jasmonate-responsive Lipoxygenase of Barley Leaves is Induced by Plant Activators but not by Pathogens J. Plant Physiol. 154, 459-462, (1999) DOI: 10.1016/S0176-1617(99)80283-1

Using the recently isolated eDNA clone LOX2 : Hv : 1 which codes for the most abundant jasmonateinducible lipoxygenase (LOX) in barley leaves (Vörös et al., 1998), we analysed the capability of different activators of systemic activated resistance (SAR) to induce the expression of that LOX. Upon treatment of barley leaves with salicylate, 2,6-dichloroisonicotinic acid and benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester, all these compounds were able to induce the expression of the LOX2 : Hv : 1 gene, whereas upon infection with the powdery mildew fungus (Blumeria graminis f. sp. hordei) mRNA accumulation was not detectable in compatible or in incompatible interactions. The induction of the LOX2 : Hv : 1 protein by SAR activators and the expression of different sets of genes induced by jasmonate and salicylate, respectively, are discussed in relation to defense responses against pathogenic fungi.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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