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Publikation

Grunwald, U.; Guo, W.; Fischer, K.; Isayenkov, S.; Ludwig-Müller, J.; Hause, B.; Yan, X.; Küster, H.; Franken, P.; Overlapping expression patterns and differential transcript levels of phosphate transporter genes in arbuscular mycorrhizal, Pi-fertilised and phytohormone-treated Medicago truncatula roots Planta 229, 1023-1034, (2009) DOI: 10.1007/s00425-008-0877-z

A microarray carrying 5,648 probes of Medicago truncatula root-expressed genes was screened in order to identify those that are specifically regulated by the arbuscular mycorrhizal (AM) fungus Gigaspora rosea, by Pi fertilisation or by the phytohormones abscisic acid and jasmonic acid. Amongst the identified genes, 21% showed a common induction and 31% a common repression between roots fertilised with Pi or inoculated with the AM fungus G. rosea, while there was no obvious overlap in the expression patterns between mycorrhizal and phytohormone-treated roots. Expression patterns were further studied by comparing the results with published data obtained from roots colonised by the AM fungi Glomus mosseae and Glomus intraradices, but only very few genes were identified as being commonly regulated by all three AM fungi. Analysis of Pi concentrations in plants colonised by either of the three AM fungi revealed that this could be due to the higher Pi levels in plants inoculated by G. rosea compared with the other two fungi, explaining that numerous genes are commonly regulated by the interaction with G. rosea and by phosphate. Differential gene expression in roots inoculated with the three AM fungi was further studied by expression analyses of six genes from the phosphate transporter gene family in M. truncatula. While MtPT4 was induced by all three fungi, the other five genes showed different degrees of repression mirroring the functional differences in phosphate nutrition by G. rosea, G. mosseae and G. intraradices.
Publikation

Deepak, S.; Shailasree, S.; Kini, R. K.; Hause, B.; Shetty, S. H.; Mithöfer, A.; Role of hydroxyproline-rich glycoproteins in resistance of pearl millet against downy mildew pathogen Sclerospora graminicola Planta 226, 323-333, (2007) DOI: 10.1007/s00425-007-0484-4

Hydroxyproline-rich glycoproteins (HRGPs) are important plant cell wall components involved in plant defense response to pathogen attack. In the present study, a resistant pearl millet (Pennisetum glaucum) cultivar, IP18292, was compared with a susceptible cultivar, 7042S, to investigate the contribution of HRGPs in the successful defense against the phytopathogenic oomycete S. graminicola. Northern hybridization using MeHRGP cDNA, a heterologous probe from cassava, indicated steady accumulation of HRGP transcripts, from 2 h.p.i. onwards with a maximum at 6 h.p.i., in the resistant cultivar. This is followed by HRGPs accumulation at about 8 h.p.i. as revealed by Western-blot analysis. Immunocytochemical localization by tissue printing and confocal immunofluorescence microscopy indicated cell walls of parenchymatic cells and the vascular tissue of coleoptile as sites of HRGP deposition. In vitro studies in the presence of horseradish peroxidase and H2O2 showed cross-linking of pearl millet HRGPs, which occurred parallel to isodityrosine accumulation. Inducible high isodityrosine content was also observed in vivo in the resistant cultivar. Here, H2O2 was found to accumulate as twin burst at 1 and 6 h.p.i., whereas in the susceptible cultivar only an early single peak was detectable. Moreover, the amount of hydroxyproline in HRGPs was about twice as high in the resistant as in the susceptible cultivar. These results suggest that cell wall strengthening in S. graminicola-infected resistant pearl millet is brought about by a combination of polypeptide cross-linking of isodityrosine as well as by the high content of hydroxyproline in HRGPs, and H2O2, in contrast to the susceptible plant.
Publikation

Kaiser, H.; Richter, U.; Keiner, R.; Brabant, A.; Hause, B.; Dräger, B.; Immunolocalisation of two tropinone reductases in potato (Solanum tuberosum L.) root, stolon, and tuber sprouts Planta 225, 127-137, (2006) DOI: 10.1007/s00425-006-0335-8

Tropinone reductases (TRs) are essential enzymes in the tropane alkaloid biosynthesis, providing either tropine for hyoscyamine and scopolamine formation or providing pseudotropine for calystegines. Two cDNAs coding for TRs were isolated from potato (Solanum tuberosum L.) tuber sprouts and expressed in E. coli. One reductase formed pseudotropine, the other formed tropine and showed kinetic properties typical for tropine-forming tropinone reductases (TRI) involved in hyoscyamine formation. Hyoscyamine and tropine are not found in S. tuberosum plants. Potatoes contain calystegines as the only products of the tropane alkaloid pathway. Polyclonal antibodies raised against both enzymes were purified to exclude cross reactions and were used for Western-blot analysis and immunolocalisation. The TRI (EC 1.1.1.206) was detected in protein extracts of tuber tissues, but mostly in levels too low to be localised in individual cells. The function of this enzyme in potato that does not form hyoscyamine is not clear. The pseudotropine-forming tropinone reductase (EC 1.1.1.236) was detected in potato roots, stolons, and tuber sprouts. Cortex cells of root and stolon contained the protein; additional strong immuno-labelling was located in phloem parenchyma. In tuber spouts, however, the protein was detected in companion cells.
Publikation

Frenzel, A.; Tiller, N.; Hause, B.; Krajinski, F.; The conserved arbuscular mycorrhiza-specific transcription of the secretory lectin MtLec5 is mediated by a short upstream sequence containing specific protein binding sites Planta 224, 792-800, (2006) DOI: 10.1007/s00425-006-0262-8

In Medicago truncatula a family of mycorrhiza-specific expressed lectins has been identified recently, but the function and regulation of these lectins during the arbuscular mycorrhiza symbiosis are still unknown. In order to characterize a first member of this protein family, MtLec5 was analyzed concerning its localization and regulation. Confocal laser scanning microscopy showed that MtLec5 is a secretory protein indicating a role as a vegetative storage protein, which is specifically expressed in mycorrhizal root systems. To study the molecular mechanisms leading to the mycorrhiza-specific transcription, deletion studies of pMtLec5 were done using reporter gene fusions. Potential cis-acting elements could be narrowed down to a 150 bp fragment that was located approximately at −300/−150 according to the transcription start, suggesting the binding of positive regulators to this area. Similar expression pattern of the reporter gene was found after transforming roots of the non-legume Nicotiana tabacum with the heterologous promoter–reporter fusions. This indicated that the observed mycorrhiza-specific transcriptional induction is not legume-specific. Electrophoretic mobility shift assays showed that several factors which were exclusively present in mycorrhizal roots bind within the 150 bp promoter area. This strengthens the hypothesis of positive regulators mediating the AM-specific gene expression.
Publikation

Hause, B.; Fester, T.; Molecular and cell biology of arbuscular mycorrhizal symbiosis Planta 221, 184-196, (2005) DOI: 10.1007/s00425-004-1436-x

The roots of most extant plants are able to become engaged in an interaction with a small group of fungi of the fungal order Glomales (Glomeromycota). This interaction—arbuscular mycorrhizal (AM) symbiosis—is the evolutionary precursor of most other mutualistic root-microbe associations. The molecular analysis of this interaction can elucidate basic principles regarding such associations. This review summarizes our present knowledge about cellular and molecular aspects of AM. Emphasis is placed on morphological changes in colonized cells, transfer of nutrients between both interacting partners, and plant defence responses. Similarities to and differences from other associations of plant and microorganisms are highlighted regarding defence reactions and signal perception.
Publikation

Opitz, S.; Schnitzler, J.-P.; Hause, B.; Schneider, B.; Histochemical analysis of phenylphenalenone-related compounds in Xiphidium caeruleum (Haemodoraceae) Planta 216, 881-889, (2003) DOI: 10.1007/s00425-002-0941-z

Phenylphenalenones represent a typical group of secondary metabolites of the Haemodoraceae. Some of these phenolic compounds show organ-specific distribution within the plant. However, detailed information on cellular localisation is still lacking. To this end, confocal laser-scanning microscopy, microspectral photometry and high-performance liquid chromatography were used to study the tissue localisation of phenylphenalenone-type compounds in Xiphidium caeruleum Aubl. From the autofluorescence potential of these compounds, specific distribution of allophanylglucosides and non-glucosidic compounds of the phenylphenalenone-type in distinct cells of the roots (apical meristem, cortex, cap, epidermis) and the shoot system was revealed. Fluorescence enhancement using "Naturstoff reagent A" (NA) indicated the occurrence of NA-positive natural products in the vacuoles of leaf epidermal cells. The present results provide new insights into the possible functions of phenylphenalenone-related compounds in the context of their localisation. Additionally, the advantages and limitations of the techniques are discussed.
Publikation

Hause, B.; Meyer, K.; Viitanen, P.; Chapple, C.; Strack, D.; Immunolocalization of 1-O-sinapoylglucose:malate sinapoyltransferase in Arabidopsis thaliana Planta 215, 26-32, (2002) DOI: 10.1007/s00425-001-0716-y

The serine carboxypeptidase-like protein 1-O-sinapoylglucose:malate sinapoyltransferase (SMT) catalyzes the transfer of the sinapoyl moiety of 1-O-sinapoylglucose to malate in the formation of sinapoylmalate in some members of the Brassicaceae. Rabbit polyclonal monospecific antibodies were raised against the recombinant SMT produced in Escherichia coli from the corresponding Arabidopsis thaliana (L.) Heynh. cDNA. Immunoblot analysis of protein from different Arabidopsis tissues showed that the SMT is produced in all plant organs, except in the seeds and young seedlings. The enzyme was most abundant in older seedlings as well as in rosette leaves and the flowering stem of the plant. Minor amounts were found in the cauline leaves, flower buds and siliques. Traces were detected in the root and flowers. Arabidopsis and transgenic tobacco (Nicotiana tabacum L.) plants expressing the full-length Arabidopsis SMT containing an N-terminal signal peptide showed apparent molecular masses of the protein of 52–55 kDa. The difference of ca. 8 kDa compared to the recombinant protein produced in E. coli was shown to be due to post-translational N-glycosylation of SMT in plants. Immunofluorescent labeling of Arabidopsis leaf sections localized SMT to the central vacuoles of mesophyll and epidermal cells. Comparable leaf sections of an SMT deletion mutant showed no vacuolar immunofluorescent labeling. We conclude that Arabidopsis SMT is synthesized as a precursor protein that is targeted to the endoplasmic reticulum where the signal peptide is removed. The correct N-terminus of the recombinantly produced SMT protein lacking the signal peptide was confirmed by Edman degradation. The protein is probably glycosylated in the Golgi apparatus from where it is subsequently routed to the vacuole.
Publikation

Fester, T.; Schmidt, D.; Lohse, S.; Walter, M. H.; Giuliano, G.; Bramley, P. M.; Fraser, P. D.; Hause, B.; Strack, D.; Stimulation of carotenoid metabolism in arbuscular mycorrhizal roots Planta 216, 148-154, (2002) DOI: 10.1007/s00425-002-0917-z

Development of arbuscular mycorrhizal roots is correlated with accumulation of various isoprenoids, i.e. acyclic C14 polyene 'mycorradicin' and C13 cyclohexenone derivatives. We present data indicating a strong stimulation of carotenoid metabolism in such roots. Carotenoid profiling revealed mycorrhiza-specific accumulation of ζ-carotene in Zea mays and Medicago truncatula. Precursor accumulation after inhibition of phytoene desaturase (Pds) activity by norflurazon indicated an increased phytoene biosynthetic capacity in mycorrhizal roots of all species analyzed. Nicotiana tabacum plants transformed with a PDS promoter-GUS construct showed a cell-specific induction of PDS promoter activity in root cells containing arbuscules. Mycorradicin biosynthesis and, partially, mycorrhization were impaired in maize mutants deficient in carotenoid biosynthesis. These data indicate that (1) mycorradicin is probably synthesized via a C40 precursor carotenoid, (2) carotenoid biosynthesis is induced in mycorrhizal roots, (3) induction occurs, at least partially, at the transcriptional level, and (4) that this may play a functional role during mycorrhization.
Publikation

Fester, T.; Strack, D.; Hause, B.; Reorganization of tobacco root plastids during arbuscule development Planta 213, 864-868, (2001) DOI: 10.1007/s004250100561

In the present paper we analyzed plastid populations labeled by the green fluorescent protein in non-mycorrhizal and mycorrhizal roots of tobacco (Nicotiana tabacum L.). We show by confocal laser scanning microscopy (i) a dramatic increase in these plastids in mycorrhizal roots and (ii) the formation of dense plastid networks covering the symbiotic interface of the arbuscular mycorrhiza, the arbuscule. These cytological observations point to an important role of root cortical cell plastids in the functioning of arbuscular mycorrhizal symbiosis.
Publikation

Hause, B.; Weichert, H.; Höhne, M.; Kindl, H.; Feussner, I.; Expression of cucumber lipid-body lipoxygenase in transgenic tobacco: lipid-body lipoxygenase is correctly targeted to seed lipid bodies Planta 210, 708-714, (2000) DOI: 10.1007/s004250050671

A particular isoform of lipoxygenase (LOX, EC 1.13.11.12) localized on lipid bodies has been shown by earlier investigations to play a role during seed germination in initiating the mobilization of triacylglycerols. On lipid bodies of germinating cucumber (Cucumis sativus L.) seedlings, the modification of linoleoyl moieties by this LOX precedes the hydrolysis of the ester bonds. We analyzed the expression and intracellular location of this particular LOX form in leaves and seeds of tobacco (Nicotiana tabacum L.) transformed with one construct coding for cucumber lipid-body LOX and one construct coding for cucumber LOX fused with a hemagglutinin epitope. In both tissues, the amount of lipid-body LOX was clearly detectable. Biochemical analysis revealed that in mature seeds the foreign LOX was targeted to lipid bodies, and the preferred location of the LOX on lipid bodies was verified by immunofluorescence microscopy. Cells of the endosperm and of the embryo exhibited fluorescence based on the immunodecoration of LOX protein whereas very weak fluorescent label was visible in seeds of untransformed control plants. Further cytochemical analysis of transformed plants showed that the LOX protein accumulated in the cytoplasm when green leaves lacking lipid bodies were analyzed. Increased LOX activity was shown in young leaves of transformed plants by an increase in the amounts of endogenous (2E)-hexenal and jasmonic acid.
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  • Martin-Luther Universität Halle
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