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Publikation

Farmer, E. E.; Gasperini, D.; Acosta, I. F.; The squeeze cell hypothesis for the activation of jasmonate synthesis in response to wounding New Phytol. 204, 282-288, (2014) DOI: 10.1111/nph.12897

Jasmonates are lipid mediators that control defence gene expression in response to wounding and other environmental stresses. These small molecules can accumulate at distances up to several cm from sites of damage and this is likely to involve cell‐to‐cell jasmonate transport. Also, and independently of jasmonate synthesis, transport and perception, different long‐distance wound signals that stimulate distal jasmonate synthesis are propagated at apparent speeds of several cm min–1 to tissues distal to wounds in a mechanism that involves clade 3 GLUTAMATE RECEPTOR‐LIKE (GLR) genes. A search for jasmonate synthesis enzymes that might decode these signals revealed LOX6, a lipoxygenase that is necessary for much of the rapid accumulation of jasmonic acid at sites distal to wounds. Intriguingly, the LOX6 promoter is expressed in a distinct niche of cells that are adjacent to mature xylem vessels, a location that would make these contact cells sensitive to the release of xylem water column tension upon wounding. We propose a model in which rapid axial changes in xylem hydrostatic pressure caused by wounding travel through the vasculature and lead to slower, radially dispersed pressure changes that act in a clade 3 GLR‐dependent mechanism to promote distal jasmonate synthesis.
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

Clarke, S. M.; Cristescu, S. M.; Miersch, O.; Harren, F. J. M.; Wasternack, C.; Mur, L. A. J.; Jasmonates act with salicylic acid to confer basal thermotolerance in Arabidopsis thaliana New Phytol. 182, 175-187, (2009) DOI: 10.1111/j.1469-8137.2008.02735.x

The cpr5‐1 Arabidopsis thaliana mutant exhibits constitutive activation of salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) signalling pathways and displays enhanced tolerance of heat stress (HS).cpr5‐1 crossed with jar1‐1 (a JA‐amino acid synthetase) was compromised in basal thermotolerance, as were the mutants opr3 (mutated in OPDA reductase3) and coi1‐1 (affected in an E3 ubiquitin ligase F‐box; a key JA‐signalling component). In addition, heating wild‐type Arabidopsis led to the accumulation of a range of jasmonates: JA, 12‐oxophytodienoic acid (OPDA) and a JA‐isoleucine (JA‐Ile) conjugate. Exogenous application of methyl jasmonate protected wild‐type Arabidopsis from HS.Ethylene was rapidly produced during HS, with levels being modulated by both JA and SA. By contrast, the ethylene mutant ein2‐1 conferred greater thermotolerance.These data suggest that JA acts with SA, conferring basal thermotolerance while ET may act to promote cell death.
Publikation

Miersch, O.; Neumerkel, J.; Dippe, M.; Stenzel, I.; Wasternack, C.; Hydroxylated jasmonates are commonly occurring metabolites of jasmonic acid and contribute to a partial switch-off in jasmonate signaling New Phytol. 177, 114-127, (2008) DOI: 10.1111/j.1469-8137.2007.02252.x

In potato 12‐hydroxyjasmonic acid (12‐OH‐JA) is a tuber‐inducing compound. Here, it is demonstrated that 12‐OH‐JA, as well as its sulfated and glucosylated derivatives, are constituents of various organs of many plant species. All accumulate differentially and usually to much higher concentrations than jasmonic acid (JA).In wounded tomato leaves, 12‐OH‐JA and its sulfated, as well as glucosylated, derivative accumulate after JA, and their diminished accumulation in wounded leaves of the JA‐deficient mutants spr2 and acx1 and also a JA‐deficient 35S::AOCantisense line suggest their JA‐dependent formation.To elucidate how signaling properties of JA/JAME (jasmonic acid methyl ester) are affected by hydroxylation and sulfation, germination and root growth were recorded in the presence of the different jasmonates, indicating that 12‐OH‐JA and 12‐hydroxyjasmonic acid sulfate (12‐HSO4‐JA) were not bioactive. Expression analyses for 29 genes showed that expression of wound‐inducible genes such as those coding for PROTEINASE INHIBITOR2, POLYPHENOL OXIDASE, THREONINE DEAMINASE or ARGINASE was induced by JAME and less induced or even down‐regulated by 12‐OH‐JA and 12‐HSO4‐JA. Almost all genes coding for enzymes in JA biosynthesis were up‐regulated by JAME but down‐regulated by 12‐OH‐JA and 12‐HSO4‐JA.The data suggest that wound‐induced metabolic conversion of JA/JAME into 12‐OH‐JA alters expression pattern of genes including a switch off in JA signaling for a subset of genes.
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.; Stenzel, I.; Hause, B.; Hause, G.; Kutter, C.; Maucher, H.; Neumerkel, J.; Feussner, I.; Miersch, O.; The wound response in tomato – Role of jasmonic acid J. Plant Physiol. 163, 297-306, (2006) DOI: 10.1016/j.jplph.2005.10.014

Plants respond to mechanical wounding or herbivore attack with a complex scenario of sequential, antagonistic or synergistic action of different signals leading to defense gene expression. Tomato plants were used as a model system since the peptide systemin and the lipid-derived jasmonic acid (JA) were recognized as essential signals in wound-induced gene expression. In this review recent data are discussed with emphasis on wound-signaling in tomato. The following aspects are covered: (i) systemin signaling, (ii) JA biosynthesis and action, (iii) orchestration of various signals such as JA, H2O2, NO, and salicylate, (iv) local and systemic response, and (v) amplification in wound signaling. The common occurrence of JA biosynthesis and systemin generation in the vascular bundles suggest JA as the systemic signal. Grafting experiments with JA-deficient, JA-insensitive and systemin-insensitive mutants strongly support this assumption.
Publikation

Schüler, G.; Mithöfer, A.; Baldwin, I. T.; BERGER, S.; Ebel, J.; Santos, J. G.; Herrmann, G.; Hölscher, D.; Kramell, R.; Kutchan, T. M.; Maucher, H.; Schneider, B.; Stenzel, I.; Wasternack, C.; Boland, W.; Coronalon: a powerful tool in plant stress physiology FEBS Lett. 563, 17-22, (2004) DOI: 10.1016/S0014-5793(04)00239-X

Coronalon, a synthetic 6‐ethyl indanoyl isoleucine conjugate, has been designed as a highly active mimic of octadecanoid phytohormones that are involved in insect and disease resistance. The spectrum of biological activities that is affected by coronalon was investigated in nine different plant systems specifically responding to jasmonates and/or 12‐oxo‐phytodienoic acid. In all bioassays analyzed, coronalon demonstrated a general strong activity at low micromolar concentrations. The results obtained showed the induction of (i) defense‐related secondary metabolite accumulation in both cell cultures and plant tissues, (ii) specific abiotic and biotic stress‐related gene expression, and (iii) root growth retardation. The general activity of coronalon in the induction of plant stress responses together with its simple and efficient synthesis suggests that this compound might serve as a valuable tool in the examination of various aspects in plant stress physiology. Moreover, coronalon might become employed in agriculture to elicit plant resistance against various aggressors.
Publikation

Bücking, H.; Förster, H.; Stenzel, I.; Miersch, O.; Hause, B.; Applied jasmonates accumulate extracellularly in tomato, but intracellularly in barley FEBS Lett. 562, 45-50, (2004) DOI: 10.1016/S0014-5793(04)00178-4

Jasmonic acid (JA) and its derivatives are well‐characterized signaling molecules in plant defense and development, but the site of their localization within plant tissue is entirely unknown. To address the question whether applied JA accumulates extracellularly or intracellularly, leaves of tomato and barley were fed with 14C‐labeled JA and the label was localized in cryofixed and lyophilized leaf tissues by microautoradiography. In tomato the radioactivity was detectable within the apoplast, but no label was found within the mesophyll cells. By contrast, in barley leaf tissues, radioactivity was detected within the mesophyll cells suggesting a cellular uptake of exogenously applied JA. JA, applied to leaves of both plants as in the labeling experiments, led in all leaf cells to the expression of JA‐inducible genes indicating that the perception is completed by JA signal transduction.
Publikation

Ratajczak, R.; Feussner, I.; Hause, B.; Böhm, A.; Parthier, B.; Wasternack, C.; Alteration of V-type H+-ATPase during methyljasmonate-induced senescence in barley (Hordeum vulgare L. cv. Salome) J. Plant Physiol. 152, 199-206, (1998) DOI: 10.1016/S0176-1617(98)80133-8

In barley leaves, the application of (−)-jasmonic acid or its methyl ester (JAME) induces a senescencelike phenotype. This is accompanied by the synthesis of abundant proteins, so-called jasmonate-induced proteins (JlPs). Here, we show that modifications of vacuolar H+-ATPase (V-ATPase) subunits are jasmo-nate inducible. Using immunofluorescence analysis, we demonstrate that V-ATPase of barley leaves is exclusively located at the tonoplast also upon JAME treatment. Total ATP-hydrolysis activity of microsomal fractions increased by a factor of 10 during 72 h of JAME-treatment, while Bafilomycin Ai-sensitive ATP-hydrolysis activity, which is usually referred to V-ATPase activity, increased by a factor of about 2 in tono-plast-enriched membrane fractions. Moreover, due to JAME treatment there was a pronounced increase in ATP-hydrolysis activity at pH 6.2. This activity was not affected by inhibitors of P-, F-, or V-ATPases. However, biochemical analysis of partially purified V-ATPase suggests, that this activity might be due at least in part to the V-ATPase. JAME-treatment seems to change biochemical properties of the V-ATPase, i.e. a shift of the pH optimum of activity to a more acidic pH and a decrease in Bafilomycin A1 sensitivity. This is accompanied by the appearance of several additional forms of V-ATPase subunits which might represent either different isoforms or post-translationally modified proteins. We suggest that these changes in properties of the V-ATPase, which is involved in house-keeping and stress responses, may be due to JAME-induced senescence to overcome concomitant changes of the vacuolar membrane.
Publikation

Bohlmann, H.; Vignutelli, A.; Hilpert, B.; Miersch, O.; Wasternack, C.; Apel, K.; Wounding and chemicals induce expression of the Arabidopsis thaliana gene Thi2.1, encoding a fungal defense thionin, via the octadecanoid pathway FEBS Lett. 437, 281-286, (1998) DOI: 10.1016/S0014-5793(98)01251-4

In seedlings of Arabidopsis thaliana the thionin gene Thi2.1 is inducible by methyl jasmonate, wounding, silver nitrate, coronatine, and sorbitol. We have used a biochemical and genetic approach to test the signal transduction of these different inducers. Both exogenously applied jasmonates and jasmonates produced endogenously upon stress induction, lead to GUS expression in a Thi2.1 promoter-uidA transgenic line. No GUS expression was observed in a coi1 mutant background which lacks jasmonate perception whereas methyl jasmonate and coronatine but not the other inducers were able to overcome the block in jasmonic acid production in a fad3-2 fad7-2 fad8 mutant background. Our results show conclusively that all these inducers regulate Thi2-1 gene expression via the octadecanoid pathway.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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