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C Wasternack - One of the best experts on this subject based on the ideXlab platform.
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Jasmonates biosynthesis perception signal transduction and action in plant stress response growth and development an update to the 2007 review in annals of botany
Annals of Botany, 2013Co-Authors: C Wasternack, B HauseAbstract:BACKGROUND: Jasmonates 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. SCOPE: The 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. CONCLUSIONS: The 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.
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Jasmonates biosynthesis perception signal transduction and action in plant stress response growth and development an update to the 2007 review in annals of botany
Annals of Botany, 2013Co-Authors: C Wasternack, B HauseAbstract:Background Jasmonates 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.
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Jasmonates an update on biosynthesis signal transduction and action in plant stress response growth and development
Annals of Botany, 2007Co-Authors: C WasternackAbstract:†Background Jasmonates 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. †Scope This 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. †Conclusions Crystal 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.
Eliezer Flescher - One of the best experts on this subject based on the ideXlab platform.
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methyl jasmonate a plant stress hormone as an anti cancer drug
Phytochemistry, 2009Co-Authors: Sharon Cohen, Eliezer FlescherAbstract:Jasmonates act as signal transduction intermediates when plants are subjected to environmental stresses such as UV radiation, osmotic shock and heat. In the past few years several groups have reported that Jasmonates exhibit anti-cancer activity in vitro and in vivo and induce growth inhibition in cancer cells, while leaving the non-transformed cells intact. Recently, Jasmonates were also discovered to have cytotoxic effects towards metastatic melanoma both in vitro and in vivo. Three mechanisms of action have been proposed to explain this anti-cancer activity. The bio-energetic mechanism - Jasmonates induce severe ATP depletion in cancer cells via mitochondrial perturbation. Furthermore, methyl jasmonate (MJ) has the ability to detach hexokinase from the mitochondria. Second, Jasmonates induce re-differentiation in human myeloid leukemia cells via mitogen-activated protein kinase (MAPK) activity and were found to act similar to the cytokinin isopentenyladenine (IPA). Third, Jasmonates induce apoptosis in lung carcinoma cells via the generation of hydrogen peroxide, and pro-apoptotic proteins of the Bcl-2 family. Combination of MJ with the glycolysis inhibitor 2-deoxy-d-glucose (2DG) and with four conventional chemotherapeutic drugs resulted in super-additive cytotoxic effects on several types of cancer cells. Finally, Jasmonates have the ability to induce death in spite of drug-resistance conferred by either p53 mutation or P-glycoprotein (P-gp) over-expression. In summary, the Jasmonates are anti-cancer agents that exhibit selective cytotoxicity towards cancer cells, and thus present hope for the development of cancer therapeutics.
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effects of natural and novel synthetic Jasmonates in experimental metastatic melanoma
British Journal of Pharmacology, 2007Co-Authors: Dorit Reischer, Alina Heyfets, Shiri Shimony, J Nordenberg, Yoel Kashman, Eliezer FlescherAbstract:Background and purpose: No current treatment reliably affects the course of metastatic melanoma. Consequently, novel approaches to the control of metastasis are actively sought. The overall goal of the present study was to identify new anti-metastatic agents active against melanoma cells. Experimental approach: Two directions were taken: 1. To determine whether the natural plant hormone methyl jasmonate, which kills cancer cells selectively, can suppress the characteristic metastatic behavior of B16-F10 melanoma cells; 2. To synthesize and identify novel jasmonate derivatives with better cytotoxic and anti-metastatic activities than methyl jasmonate. Key results: We found that methyl jasmonate suppressed B16-F10 cell motility and inhibited the development of experimental lung metastases of these cells. Furthermore, methyl jasmonate suppressed the motility of a sub-clone of these cells over-expressing P-glycoprotein and exhibiting multidrug resistance. The synthetic derivative Compound I (5,7,9,10-tetrabromo derivative of methyl jasmonate, the most active derivative) had greater cytotoxic potency (IC50, 0.04mM) than methyl jasmonate (IC50, 2.6mM). Compound I prevented B16-F10 cell adhesion efficiently and inhibited the development of lung metastases at a much lower dose than methyl jasmonate. Conclusions and Implications: Natural and synthetic Jasmonates have anti-metastatic actions. Further development of these agents for the suppression of metastasis in melanoma and other types of cancer is warranted. British Journal of Pharmacology (2007) 150, 738–749. doi:10.1038/sj.bjp.0707146
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Jasmonates in cancer therapy
Cancer Letters, 2007Co-Authors: Eliezer FlescherAbstract:Several groups have reported in recent years that members of the plant stress hormones family of Jasmonates, and some of their synthetic derivatives, exhibit anti-cancer activity in vitro and in vivo. Jasmonates increased the life span of EL-4 lymphoma-bearing mice, and exhibited selective cytotoxicity towards cancer cells while sparing normal blood lymphocytes, even when the latter were part of a mixed population of leukemic and normal cells drawn from the blood of chronic lymphocytic leukemia (CLL) patients. Jasmonates join a growing number of old and new cancer chemotherapeutic compounds of plant origin. Three mechanisms of action have been proposed to explain the anti-cancer activity of Jasmonates. These include: (1) The bio-energetic mechanism-Jasmonates induce severe ATP depletion in cancer cells via mitochondrial perturbation; (2) The re-differentiation mechanism-Jasmonates induce re-differentiation in human myeloid leukemia cells via mitogen-activated protein kinase (MAPK) activity; (3) The reactive oxygen species (ROS)-mediated mechanism-Jasmonates induce apoptosis in lung carcinoma cells via the generation of hydrogen peroxide, and pro-apoptotic proteins of the Bcl-2 family. Several similarities between the effects of Jasmonates on plant and cancer cells have been recorded, suggesting that additional analysis of jasmonate effects in plant cells may contribute to a deeper understanding of the anti-cancer actions of these compounds. Those similarities include: induction of cell death, suppression of proliferation and cell cycle arrest, MAPK induction, ROS generation, and enhancement of heat-shock proteins (HSP) expression. Finally, Jasmonates can induce death in drug-resistant cells. The drug resistance was conferred by either p53 mutation or P-glycoprotein (P-gp) over-expression. In summary, the jasmonate family of novel anti-cancer agents presents new hope for the development of cancer therapeutics, which should attract further scientific and pharmaceutical interest.
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Jasmonates induce nonapoptotic death in high resistance mutant p53 expressing b lymphoma cells
British Journal of Pharmacology, 2005Co-Authors: Orit Fingrut, Ronit Rotem, Dorit Reischer, Natalia Goldin, Irit Altboum, Israel Zanbar, Eliezer FlescherAbstract:Mutations in p53, a tumor suppressor gene, occur in more than half of human cancers. Therefore, we tested the hypothesis that Jasmonates (novel anticancer agents) can induce death in mutated p53-expressing cells. Two clones of B-lymphoma cells were studied, one expressing wild-type (wt) p53 and the other expressing mutated p53. Jasmonic acid and methyl jasmonate (0.25–3 mM) were each equally cytotoxic to both clones, whereas mutant p53-expressing cells were resistant to treatment with the radiomimetic agent neocarzinostatin and the chemotherapeutic agent bleomycin. Neocarzinostatin and bleomycin induced an elevation in the p53 levels in wt p53-expressing cells, whereas methyl jasmonate did not. Methyl jasmonate induced mostly apoptotic death in the wt p53-expressing cells, while no signs of early apoptosis were detected in mutant p53-expressing cells. In contrast, neocarzinostatin and bleomycin induced death only in wt p53-expressing cells, in an apoptotic mode. Methyl jasmonate induced a rapid depletion of ATP in both clones. In both clones, oligomycin (a mitochondrial ATP synthase inhibitor) did not increase ATP depletion induced by methyl jasmonate, whereas inhibition of glycolysis with 2-deoxyglucose did. High glucose levels protected both clones from methyl jasmonate-induced ATP depletion (and reduced methyl jasmonate-induced cytotoxicity), whereas high levels of pyruvate did not. These results suggest that methyl jasmonate induces ATP depletion mostly by compromising oxidative phosphorylation in the mitochondria. In conclusion, Jasmonates can circumvent the resistance of mutant p53-expressing cells towards chemotherapy by inducing a nonapoptotic cell death. British Journal of Pharmacology (2005) 146, 800–808. doi:10.1038/sj.bjp.0706394
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Jasmonates a new family of anti cancer agents
Anti-Cancer Drugs, 2005Co-Authors: Eliezer FlescherAbstract:Since salicylate, a plant stress hormone, suppresses the growth of various types of cancer cells, it was deemed of interest to investigate whether the jasmonate family of plant stress hormones is endowed with anti-cancer activities. Cell lines representing a wide spectrum of malignancies, including prostate, breast and lung, exhibit sensitivity to the cytotoxic effects of methyl jasmonate (MJ). Jasmonates induced death in leukemic cells isolated from the blood of chronic lymphocytic leukemia (CLL) patients and increased significantly the survival of lymphoma-bearing mice. Among the naturally occurring Jasmonates, MJ is the most active, while the synthetic methyl-4,5-didehydrojasmonate, was approximately 29-fold more active than MJ. The cytotoxic activity of MJ is independent of transcription and translation. Studies have suggested several mechanisms of action. It appears that while prolonged exposures to relatively low concentrations of Jasmonates induce growth arrest and re-differentiation in myeloid leukemia cells, higher concentrations of MJ induce direct perturbation of cancer cell mitochondria, leading to the release of cytochrome c and eventual cell death. A most important characteristic of Jasmonates is their ability to selectively kill cancer cells while sparing normal cells. Even within a mixed population of normal and leukemic cells derived from the blood of CLL patients, MJ killed preferentially the leukemic cells. In conclusion, Jasmonates present a unique class of anti-cancer compounds which deserves continued research at the basic and pharmaceutical levels in order to yield novel chemotherapeutic agents against a range of neoplastic diseases.
Johan Memelink - One of the best experts on this subject based on the ideXlab platform.
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the basic helix loop helix transcription factor crmyc2 controls the jasmonate responsive expression of the orca genes that regulate alkaloid biosynthesis in catharanthus roseus
Plant Journal, 2011Co-Authors: Hongtao Zhang, Sabah Hedhili, Gregory Montiel, Yanxia Zhang, Guillaume Chatel, Martial Pre, Pascal Gantet, Johan MemelinkAbstract:Jasmonates are plant signalling molecules that play key roles in defence against insects and certain pathogens, among others by controlling the biosynthesis of protective secondary metabolites. In Catharanthus roseus, the AP2/ERF-domain transcription factor ORCA3 controls the jasmonate-responsive expression of several genes encoding enzymes involved in terpenoid indole alkaloid biosynthesis. ORCA3 gene expression is itself induced by jasmonate. The ORCA3 promoter contains an autonomous jasmonate-responsive element (JRE) composed of a quantitative sequence responsible for the high level of expression and a qualitative sequence that acts as an on/off switch in response to methyl-jasmonate (MeJA). Here, we identify the basic helix-loop-helix (bHLH) transcription factor CrMYC2 as the major activator of MeJA-responsive ORCA3 gene expression. The CrMYC2 gene is an immediate-early jasmonate-responsive gene. CrMYC2 binds to the qualitative sequence in the ORCA3 JRE in vitro, and transactivates reporter gene expression via this sequence in transient assays. Knock-down of the CrMYC2 expression level via RNA interference caused a strong reduction in the level of MeJA-responsive ORCA3 mRNA accumulation. In addition, MeJA-responsive expression of the related transcription factor gene ORCA2 was significantly reduced. Our results show that MeJA-responsive expression of alkaloid biosynthesis genes in C. roseus is controlled by a transcription factor cascade consisting of the bHLH protein CrMYC2 regulating ORCA gene expression, and the AP2/ERF-domain transcription factors ORCA2 and ORCA3, which in turn regulate a subset of alkaloid biosynthesis genes.
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regulation of gene expression by jasmonate hormones
ChemInform, 2010Co-Authors: Johan MemelinkAbstract:Abstract Plants possess inducible defense systems to oppose attack by pathogens and herbivores. Jasmonates are important signaling molecules produced by plants which regulate in positive or negative crosstalk with ethylene subsets of genes involved in defense against necrotrophic microorganisms or herbivorous insects, respectively. This review presents an overview of promoter sequences and transcription factors involved in jasmonate-responsive gene expression with the most important components summarized here. Frequently occurring jasmonate-responsive promoter sequences are the GCC motif, which is commonly found in promoters activated synergistically by jasmonate and ethylene, and the G-box, which is commonly found in promoters activated by Jasmonates and repressed by ethylene. Important transcription factors conferring jasmonate-responsive gene expression in Arabidopsis are ORA59 and AtMYC2. ORA59 interacts with the GCC motif and controls the expression of genes that are synergistically induced by Jasmonates and ethylene, whereas AtMYC2 interacts with the G-box and related sequences, and controls genes activated by jasmonate alone. AtMYC2 can interact with JAZ proteins, which are hypothesized to act as repressors. The bioactive jasmonate (+)-7- iso -JA- l -Ile promotes the interaction between the ubiquitin ligase complex SCF COI1 and JAZ proteins, resulting in their degradation by the 26S proteasome, thereby liberating AtMYC2 from repression according to the prevailing model. Literature up to 1 June 2009 was used for this review.
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identification of a bipartite jasmonate responsive promoter element in the catharanthus roseus orca3 transcription factor gene that interacts specifically with at hook dna binding proteins
Plant Physiology, 2007Co-Authors: Debora Vom Endt, Giancarlo Pasquali, Jan W Kijne, Marina Soares E Silva, Johan MemelinkAbstract:Jasmonates are plant signaling molecules that play key roles in defense against certain pathogens and insects, among others, by controlling the biosynthesis of protective secondary metabolites. In Catharanthus roseus, the APETALA2-domain transcription factor ORCA3 is involved in the jasmonate-responsive activation of terpenoid indole alkaloid biosynthetic genes. ORCA3 gene expression is itself induced by jasmonate. By loss- and gain-of-function experiments, we located a 74-bp region within the ORCA3 promoter, which contains an autonomous jasmonate-responsive element (JRE). The ORCA3 JRE is composed of two important sequences: a quantitative sequence responsible for a high level of expression and a qualitative sequence that appears to act as an on/off switch in response to methyl jasmonate. We isolated 12 different DNA-binding proteins having one of four different types of DNA-binding domains, using the ORCA3 JRE as bait in a yeast (Saccharomyces cerevisiae) one-hybrid transcription factor screening. The binding of one class of proteins bearing a single AT-hook DNA-binding motif was affected by mutations in the quantitative sequence within the JRE. Two of the AT-hook proteins tested had a weak activating effect on JRE-mediated reporter gene expression, suggesting that AT-hook family members may be involved in determining the level of expression of ORCA3 in response to jasmonate.
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involvement of the octadecanoid pathway and protein phosphorylation in fungal elicitor induced expression of terpenoid indole alkaloid biosynthetic genes in catharanthus roseus
Plant Physiology, 1999Co-Authors: Frank L H Menke, Stefanie Parchmann, Jan W Kijne, Johan MemelinkAbstract:Two key genes in terpenoid indole alkaloid biosynthesis, Tdc and Str , encoding tryptophan decarboxylase and strictosidine synthase, respectively, are coordinately induced by fungal elicitors in suspension-cultured Catharanthus roseus cells. We have studied the roles of the jasmonate biosynthetic pathway and of protein phosphorylation in signal transduction initiated by a partially purified elicitor from yeast extract. In addition to activating Tdc and Str gene expression, the elicitor also induced the biosynthesis of jasmonic acid. The jasmonate precursor α-linolenic acid or methyl jasmonate (MeJA) itself induced Tdc and Str gene expression when added exogenously . Diethyldithiocarbamic acid, an inhibitor of jasmonate biosynthesis, blocked both the elicitor-induced formation of jasmonic acid and the activation of terpenoid indole alkaloid biosynthetic genes. The protein kinase inhibitor K-252a abolished both elicitor-induced jasmonate biosynthesis and MeJA-induced Tdc and Str gene expression. Analysis of the expression of Str promoter/ gusA fusions in transgenic C. roseus cells showed that the elicitor and MeJA act at the transcriptional level. These results demonstrate that the jasmonate biosynthetic pathway is an integral part of the elicitor-triggered signal transduction pathway that results in the coordinate expression of the Tdc and Str genes and that protein kinases act both upstream and downstream of Jasmonates.
B Hause - One of the best experts on this subject based on the ideXlab platform.
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Jasmonates biosynthesis perception signal transduction and action in plant stress response growth and development an update to the 2007 review in annals of botany
Annals of Botany, 2013Co-Authors: C Wasternack, B HauseAbstract:BACKGROUND: Jasmonates 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. SCOPE: The 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. CONCLUSIONS: The 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.
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Jasmonates biosynthesis perception signal transduction and action in plant stress response growth and development an update to the 2007 review in annals of botany
Annals of Botany, 2013Co-Authors: C Wasternack, B HauseAbstract:Background Jasmonates 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.
Axel Mithofer - One of the best experts on this subject based on the ideXlab platform.
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omega hydroxylated ja ile is an endogenous bioactive jasmonate that signals through the canonical jasmonate signaling pathway
Biochimica et Biophysica Acta, 2019Co-Authors: Guillermo Hugo Jimenezaleman, Marilia Almeidatrapp, Gemma Fernandezbarbero, Selena Gimenezibanez, Michael Reichelt, Jyothilakshmi Vadassery, Axel Mithofer, Julio Caballero, Wilhelm Boland, Roberto SolanoAbstract:Jasmonates are fatty acid derivatives that control several plant processes including growth, development and defense. Despite the chemical diversity of Jasmonates, only jasmonoyl-L-isoleucine (JA-Ile) has been clearly characterized as the endogenous ligand of the jasmonate co-receptors (COI1-JAZs) in higher plants. Currently, it is accepted that ω-hydroxylation of JA-Ile leads to inactivation of the molecule. This study shows that ω-hydroxylated JA-Ile (12-OH-JA-Ile) retains bioactivity and signals through the canonical JA-pathway. The results suggest that 12-OH-JA-Ile differentially activates a subset of JA-Ile co-receptors that may control and/or modulate particular jasmonate dependent responses. It is proposed that after a strong immune response mediated by JA-Ile, the ω-hydroxylated form modulates JA-Ile activated processes thereby improving plant resilience.
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Tendril Coiling in Grapevine: Jasmonates and a New Role for GABA?
Journal of Plant Growth Regulation, 2019Co-Authors: Jaiana Malabarba, Michael Reichelt, Giancarlo Pasquali, Axel MithoferAbstract:Grapevine ( Vitis vinifera L., Vitaceae) belongs to the genus Vitis , and is characterized as a vine due to the presence of tendrils, which are located opposite to leaves. Tendrils are thigmo-responsive organs, able to carry out delicate mechanosensory responses upon touch and related stimuli. These organs are an adaptation of the plant to climb with the help of support to higher places and finally remain at a position with favorable light quality. In previous studies on Bryonia dioica (Cucurbitaceae), phytohormones of the jasmonate class were identified as the endogenous hormone signals to initiate coiling of the tendrils. Strikingly, this is still the only example for jasmonate-induced tendril coiling. In grapevine, three compounds (12-oxo-phytodienoic acid, jasmonic acid (JA), and JA isoleucine conjugate) of the jasmonate class were found at higher concentrations in non-coiled tendrils when compared with coiled ones. Upon treatment with phytohormones, we could confirm the activity of Jasmonates on tendril coiling in grapevine. However, not Jasmonates but a non-proteinogenic amino acid, γ-aminobutyric acid (GABA), was detected to accumulate in grapevine tendrils at significantly higher levels than in all other tissues, independent of their coiling status. For GABA we detected a significant, transient positive effect on tendril coiling. Use of a GABA synthesis blocker, 3-mercaptopropionic acid, caused reduced GABA- but not JA-induced coiling scores. No additive effect of JA plus GABA was detectable on the tendrils’ coiling score. Thus, for grapevine, our data demonstrate a strong activity of Jasmonates in tendril coiling induction even without mechanical stimuli and, furthermore, the data also suggest that GABA can independently promote tendril coiling.
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Neomycin: An Effective Inhibitor of Jasmonate-Induced Reactions in Plants
Journal of Plant Growth Regulation, 2019Co-Authors: Jyothilakshmi Vadassery, Meredith C Schuman, Daniel Ballhorn, Steven Fleming, Christian Mazars, Shree P. Pandey, Axel Schmidt, Kai-wun Yeh, Ayufu Yilamujiang, Axel MithoferAbstract:Jasmonates are important phytohormones involved in both plant developmental processes as well as defense reactions. Many JA-mediated plant defense responses have been studied in model plants using mutants of the jasmonate signaling pathway. However, in plant species where JA-signaling mutants are not accessible, the availability of a tool targeting JA signaling is crucial to investigate jasmonate-dependent processes. Neomycin is a poly-cationic aminoglycoside antibiotic that blocks the release of Ca 2+ from internal stores. We examined the inhibitory activities of neomycin on different jasmonate-inducible responses in eight different plant species: Intracellular calcium measurements in Nicotiana tabacum cell culture, Sporamin gene induction in Ipomoea batatas, PDF2.2 gene expression in Triticum aestivum, Nepenthesin protease activity measurement in Nepenthes alata, extrafloral nectar production in Phaseolus lunatus, nectary formation in Populus trichocarpa, terpene accumulation in Picea abies, and secondary metabolite generation in Nicotiana attenuata. We are able to show that neomy-cin, an easily manageable and commercially available compound, inhibits JA-mediated responses across the plant kingdom.
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Image_1_A Holistic Approach to Analyze Systemic Jasmonate Accumulation in Individual Leaves of Arabidopsis Rosettes Upon Wounding.pdf
2018Co-Authors: Monika Heyer, Michael Reichelt, Axel MithoferAbstract:Phytohormones, especially Jasmonates, are known to be mediators of the plant responses to wounding and herbivore feeding. Their role in such stress responses has been largely studied locally in treated leaves. However, less is known about the induced systemic distribution of phytohormone signals upon these kinds of stresses. Here, a holistic approach was performed in order to investigate the systemic phytohormone pattern in the rosette of Arabidopsisthaliana after herbivore-related wounding. Levels of different stress-related phytohormones such as Jasmonates, abscisic acid, and salicylic acid were analyzed in individual leaves. We demonstrate that the typically used sampling method, where leaves are first cut and immediately frozen, causes false-positive results since cutting already induces systemic jasmonate elevations within less than 1.6 min. Therefore, this approach is not suitable to study systemic phytohormone changes in the whole plant. By developing a new method where leaves are frozen first and subsequently cut, sampling-induced phytohormone elevations could be reduced. Using this new method, we show that jasmonic acid and its active isoleucine conjugate (jasmonoyl-isoleucine) are involved in the fast systemic wound response of Arabidopsis. A systemic induction of the Jasmonates’ precursor, 12-oxo-phytodienoic acid, was not observed throughout our treatments. The systemic phytohormone distribution pattern is strongly linked to the vascular connections between the leaves, providing further evidence that the vascular system is used for long distance-signaling in Arabidopsis. Besides already known vascular connections, we also demonstrate that the systemic distribution of jasmonate signals can be extended to distant leaves, which are systemically but indirectly connected via another vascularly connected leaf. This holistic approach covering almost the whole Arabidopsis rosette introduces a method to overcome false-positive results in systemic phytohormone determinations and demonstrates that wounding-induced long-distance signaling includes fast changes in jasmonate levels in systemic, non-treated leaves.
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wound and insect induced jasmonate accumulation in carnivorous drosera capensis two sides of the same coin
Plant Biology, 2014Co-Authors: Axel Mithofer, Michael Reichelt, Yoko NakamuraAbstract:Carnivorous sundew plants catch and digest insect prey for their own nutrition. The sundew species Drosera capensis shows a pronounced leaf bending reaction upon prey capture in order to form an 'outer stomach'. This formation is triggered by Jasmonates, phytohormones typically involved in defence reactions against herbivory and wounding. Whether Jasmonates still have this function in D. capensis in addition to mediating the leaf bending reaction was investigated here. Wounded, insect prey-fed and insect-derived oral secretion-treated leaves of D. capensis were analysed for Jasmonates (jasmonic acid, JA; jasmonic acid-isoleucine conjugate, JA-Ile) using LC-MS/MS. Prey-induced jasmonate accumulation in D. capensis leaves was persistent, and showed high levels of JA and JA-Ile (575 and 55.7 pmol · g · FW(-1) , respectively), whereas wounding induced a transient increase of JA (maximum 500 pmol · g · FW(-1) ) and only low (3.1 pmol · g · FW(-1) ) accumulation of JA-Ile. Herbivory, mimicked with a combined treatment of wounding plus oral secretion (W+OS) obtained from Spodoptera littoralis larvae induced both JA (4000 pmol · g · FW(-1) ) and JA-Ile (25 pmol · g · FW(-1) ) accumulation, with kinetics similar to prey treatment. Only prey and W+OS, but not wounding alone or OS, induced leaf bending. The results indicate that both mechanical and chemical stimuli trigger JA and JA-Ile synthesis. Differences in kinetics and induced jasmonate levels suggest different sensing and signalling events upon injury and insect-dependent challenge. Thus, in Drosera, Jasmonates are still part of the response to wounding. Jasmonates are also employed in insect-induced reactions, including responses to herbivory and carnivory.
