zur Suche springenzur Navigation springenzum Inhalt springen

Publikationen - Molekulare Signalverarbeitung

Sortieren nach: Erscheinungsjahr Typ der Publikation

Zeige Ergebnisse 1 bis 10 von 18.

Publikation

Serra, P.; Carbonell, A.; Navarro, B.; Gago-Zachert, S.; Li, S.; Di Serio, F.; Flores, R.; Symptomatic plant viroid infections in phytopathogenic fungi: A request for a critical reassessment Proc. Natl. Acad. Sci. U.S.A. 117, 10126-10128, (2020) DOI: 10.1073/pnas.1922249117

0
Publikation

Carbonell, A.; Flores, R.; Gago, S.; Trans-cleaving hammerhead ribozymes with tertiary stabilizing motifs: in vitro and in vivo activity against a structured viroid RNA Nucleic Acids Res. 39, 2432-2444, (2011) DOI: 10.1093/nar/gkq1051

Trans -cleaving hammerheads with discontinuous or extended stem I and with tertiary stabilizing motifs (TSMs) have been tested previously against short RNA substrates in vitro at low Mg 2+ concentration. However, the potential of these ribozymes for targeting longer and structured RNAs in vitro and in vivo has not been examined. Here, we report the in vitro cleavage of short RNAs and of a 464-nt highly structured RNA from potato spindle tuber viroid (PSTVd) by hammerheads with discontinuous and extended formats at submillimolar Mg 2+ . Under these conditions, hammerheads derived from eggplant latent viroid and peach latent mosaic viroid (PLMVd) with discontinuous and extended formats, respectively, where the most active. Furthermore, a PLMVd-derived hammerhead with natural TSMs showed activity in vivo against the same long substrate and interfered with systemic PSTVd infection, thus reinforcing the idea that this class of ribozymes has potential to control pathogenic RNA replicons.
Publikation

Flores, R.; Gas, M.-E.; Molina-Serrano, D.; Nohales, M.-?.; Carbonell, A.; Gago, S.; De la Peña, M.; Daròs, J.-A.; Viroid Replication: Rolling-Circles, Enzymes and Ribozymes Viruses 1, 317-334, (2009) DOI: 10.3390/v1020317

Viroids, due to their small size and lack of protein-coding capacity, must rely essentially on their hosts for replication. Intriguingly, viroids have evolved the ability to replicate in two cellular organella, the nucleus (family Pospiviroidae) and the chloroplast (family Avsunviroidae). Viroid replication proceeds through an RNA-based rolling-circle mechanism with three steps that, with some variations, operate in both polarity strands: i) synthesis of longer-than-unit strands catalyzed by either the nuclear RNA polymerase II or a nuclear-encoded chloroplastic RNA polymerase, in both instances redirected to transcribe RNA templates, ii) cleavage to unit-length, which in the family Avsunviroidae is mediated by hammerhead ribozymes embedded in both polarity strands, while in the family Pospiviroidae the oligomeric RNAs provide the proper conformation but not the catalytic activity, and iii) circularization. The host RNA polymerases, most likely assisted by additional host proteins, start transcription from specific sites, thus implying the existence of viroid promoters. Cleavage and ligation in the family Pospiviroidae is probably catalyzed by an RNase III-like enzyme and an RNA ligase able to circularize the resulting 5’ and 3’ termini. Whether a chloroplastic RNA ligase mediates circularization in the family Avsunviroidae, or this reaction is autocatalytic, remains an open issue.
Publikation

Carbonell, A.; Martínez de Alba, A.-E.; Flores, R.; Gago, S.; Double-stranded RNA interferes in a sequence-specific manner with the infection of representative members of the two viroid families Virology 371, 44-53, (2008) DOI: 10.1016/j.virol.2007.09.031

Infection by viroids, non-protein-coding circular RNAs, occurs with the accumulation of 21–24 nt viroid-derived small RNAs (vd-sRNAs) with characteristic properties of small interfering RNAs (siRNAs) associated to RNA silencing. The vd-sRNAs most likely derive from dicer-like (DCL) enzymes acting on viroid-specific dsRNA, the key elicitor of RNA silencing, or on the highly structured genomic RNA. Previously, viral dsRNAs delivered mechanically or agroinoculated have been shown to interfere with virus infection in a sequence-specific manner. Here, we report similar results with members of the two families of nuclear- and chloroplast-replicating viroids. Moreover, homologous vd-sRNAs co-delivered mechanically also interfered with one of the viroids examined. The interference was sequence-specific, temperature-dependent and, in some cases, also dependent on the dose of the co-inoculated dsRNA or vd-sRNAs. The sequence-specific nature of these effects suggests the involvement of the RNA induced silencing complex (RISC), which provides sequence specificity to RNA silencing machinery. Therefore, viroid titer in natural infections might be regulated by the concerted action of DCL and RISC. Viroids could have evolved their secondary structure as a compromise between resistance to DCL and RISC, which act preferentially against RNAs with compact and relaxed secondary structures, respectively. In addition, compartmentation, association with proteins or active replication might also help viroids to elude their host RNA silencing machinery.
Publikation

Carbonell, A.; De la Peña, M.; Flores, R.; Gago, S.; Effects of the trinucleotide preceding the self-cleavage site on eggplant latent viroid hammerheads: differences in co- and post-transcriptional self-cleavage may explain the lack of trinucleotide AUC in most natural hammerheads Nucleic Acids Res. 34, 5613-5622, (2006) DOI: 10.1093/nar/gkl717

Eggplant latent viroid (ELVd) can form stable hammerhead structures in its (+) and (−) strands. These ribozymes have the longest helices I reported in natural hammerheads, with that of the ELVd (+) hammerhead being particularly stable (5/7 bp are G-C). Moreover, the trinucleotide preceding the self-cleavage site of this hammerhead is AUA, which together with GUA also found in some natural hammerheads, deviate from the GUC present in most natural hammerheads including the ELVd (−) hammerhead. When the AUA trinucleotide preceding the self-cleavage site of the ELVd (+) hammerhead was substituted by GUA and GUC, as well as by AUC (essentially absent in natural hammerheads), the values of the self-cleavage rate constants at low magnesium of the purified hammerheads were: ELVd-(+)-AUC≈ELVd-(+)-GUC>ELVd-(+)-GUA> ELVd-(+)-AUA. However, the ELVd-(+)-AUC hammerhead was the catalytically less efficient during in vitro transcription, most likely because of the transient adoption of catalytically-inactive metastable structures. These results suggest that natural hammerheads have been evolutionary selected to function co-transcriptionally, and provide a model explaining the lack of trinucleotide AUC preceding the self-cleavage site of most natural hammerheads. Comparisons with other natural hammerheads showed that the ELVd-(+)-GUC and ELVd-(+)-AUC hammerheads are the catalytically most active in a post-transcriptional context with low magnesium.
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

Sharma, V. K.; Monostori, T.; Hause, B.; Maucher, H.; Göbel, C.; Hornung, E.; Hänsch, R.; Bittner, F.; Wasternack, C.; Feussner, I.; Mendel, R. R.; Schulze, J.; Genetic transformation of barley to modify expression of a 13-lipoxygenase Acta Biol. Szeged. 49, 33-34, (2005)

Immature scutella of barley were transformed with cDNA coding for a 13-lipoxygenase of barley (LOX-100) via particle bombardment. Regenerated plants were tested by PAT-assay, Western-analysis and PCR-screening. Immunocytochemical assay of T0 plants showed expression of the LOX cDNA both in the chloroplasts and in the cytosol, depending on the presence of the chloroplast signal peptide sequences in the cDNA. A few transgenic plants containing higher amounts of LOX-derived products have been found. These are the candidates for further analysis concerning pathogen resistance.
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

Miersch, O.; Weichert, H.; Stenzel, I.; Hause, B.; Maucher, H.; Feussner, I.; Wasternack, C.; Constitutive overexpression of allene oxide cyclase in tomato (Lycopersicon esculentum cv. Lukullus) elevates levels of some jasmonates and octadecanoids in flower organs but not in leaves Phytochemistry 65, 847-856, (2004) DOI: 10.1016/j.phytochem.2004.01.016

The allene oxide cyclase (AOC), an enzyme in jasmonate biosynthesis, occurs in vascular bundles and ovules of tomato flowers which exhibit a tissue-specific oxylipin signature (Plant J. 24, 113-126, 2000). Constitutive overexpression of the AOC did not led to altered levels of jasmonates in leaves, but these levels increased upon wounding or other stresses suggesting regulation of jasmonate biosynthesis by substrate availability (Plant J. 33, 577-589, 2003). Here, we show dramatic changes in levels of jasmonic acid (JA), of 12-oxo-phytodienoic acid (OPDA), their methyl esters (JAME, OPDAME), and of dinor-OPDA in most flower organs upon constitutive overexpression of AOC. Beside a dominant occurrence of OPDAME and JA in most flower organs, the ratio among the various compounds was altered differentially in the organs of transgenic flowers, e.g. OPDAME increased up to 53-fold in stamen, and JA increased about 51-fold in buds and 7.5-fold in sepals. The increase in jasmonates and octadecanoids was accompanied by decreased levels of free lipid hydro(per)oxy compounds. Except for 16:2, the AOC overexpression led to a significant increase in free but not esterified polyunsaturated fatty acids in all flower organs. The data suggest different regulation of JA biosynthesis in leaves and flowers of tomato.Constitutive overexpression of the AOC increases in all flower organs levels of some jasmonates and octadecanoids, alters the ratios among the compounds, decreases levels of free lipid hydro(per)oxy compounds and increases levels of free but not of esterified polyunsaturated fatty acids.
Publikation

Maucher, H.; Stenzel, I.; Miersch, O.; Stein, N.; Prasad, M.; Zierold, U.; Schweizer, P.; Dorer, C.; Hause, B.; Wasternack, C.; The allene oxide cyclase of barley (Hordeum vulgare L.)—cloning and organ-specific expression Phytochemistry 65, 801-811, (2004) DOI: 10.1016/j.phytochem.2004.01.009

The naturally occurring enantiomer of the various octadecanoids and jasmonates is established in a biosynthetic step catalyzed by the allene oxide cyclase (AOC). The AOC converts an allene oxide formed by an allene oxide synthase (AOS). Here, we show cloning and characterization of cDNAs encoding the AOC and a third AOS, respectively, in addition to the two AOSs previously published (Plant J. 21, 199–213, 2000). The ORF of the AOC-cDNA of 717 bp codes for a protein of 238 amino acid residues carrying a putative chloroplast target sequence. Overexpression without chloroplast target sequence revealed AOC activity. The AOC was found to be a single copy gene which mapped on chromosome 6H. AOC mRNA accumulation appeared in leaf segments upon treatment with various jasmonates, octadecanoids and ABA or during stress such as treatment with sorbitol or glucose solutions. Infection with powdery mildew activated AOC expression in susceptible and resistant lines of barley which correlated with PR1b expression. Among different tissues of barley seedlings, the scutellar node and leaf base accumulated AOC mRNA preferentially which correlated with accumulation of mRNAs for other biosynthetic enzymes (lipoxygenases, AOSs). AOC mRNA accumulation appeared also abundantly in parts of the root containing the tip and correlated with elevated levels of jasmonates. The data suggest a link of AOC expression and JA formation and support role of JA in stress responses and development of barley.Barley plants contain one allene oxide cyclase and three allene oxide synthases which are up-regulated during seedling development accompanied by elevated levels of jasmonate.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
IPB Mainnav Search