Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
To explore the chemical composition of root exudates of the model plant Arabidopsis thaliana a workflow for nontargeted metabolite profiling of the semipolar fraction of root exudates was developed. It comprises hydroponic plant cultivation and sampling of root exudates under sterile conditions, sample preparation by solid-phase extraction and analysis by reversed-phase UPLC/ESI-QTOFMS. Following the established workflow, root exudates of six-week-old plants were profiled and a set of reproducibly occurring molecular features was compiled. To structurally elucidate the corresponding metabolites, accurate mass tandem mass spectrometry and on-line hydrogen/deuterium exchange were applied. Currently, a total of 103 compounds were detected and annotated by elemental composition of which more than 90 were structurally characterized or classified. Among them, 42 compounds were rigorously identified using an authenticated standard. The compounds identified so far include nucleosides, deoxynucleosides, aromatic amino acids, anabolites and catabolites of glucosinolates, dipeptides, indolics, salicylic and jasmonic acid catabolites, coumarins, mono-, di- and trilignols, hydroxycinnamic acid derivatives and oxylipins and exemplify the high chemical diversity of plant root exudates.
Publikation
Landtag, J.; Baumert, A.; Degenkolb, T.; Schmidt, J.; Wray, V.; Scheel, D.; Strack, D.; Rosahl, S.;Accumulation of tyrosol glucoside in transgenic potato plants expressing a parsley tyrosine decarboxylasePhytochemistry60683-689(2002)DOI: 10.1016/S0031-9422(02)00161-9
As part of the response to pathogen infection, potato plants accumulate soluble and cell wall-bound phenolics such as hydroxycinnamic acid tyramine amides. Since incorporation of these compounds into the cell wall leads to a fortified barrier against pathogens, raising the amounts of hydroxycinnamic acid tyramine amides might positively affect the resistance response. To this end, we set out to increase the amount of tyramine, one of the substrates of the hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)-transferase reaction, by placing a cDNA encoding a pathogen-induced tyrosine decarboxylase from parsley under the control of the 35S promoter and introducing the construct into potato plants via Agrobacterium tumefaciens-mediated transformation. While no alterations were observed in the pattern and quantity of cell wall-bound phenolic compounds in transgenic plants, the soluble fraction contained several new compounds. The major one was isolated and identified as tyrosol glucoside by liquid chromatography–electrospray ionization–high resolution mass spectrometry and NMR analyses. Our results indicate that expression of a tyrosine decarboxylase in potato does not channel tyramine into the hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)-transferase reaction but rather unexpectedly, into a different pathway leading to the formation of a potential storage compound.Expression of a parsley tyrosine decarboxylase in potato unexpectedly channels tyramine into a pathway leading to the formation of tyrosol glucoside.
Publikation
Brunner, F.; Wirtz, W.; Rose, J. K. C.; Darvill, A. G.; Govers, F.; Scheel, D.; Nürnberger, T.;A β-glucosidase/xylosidase from the phytopathogenic oomycete, Phytophthora infestansPhytochemistry59689-696(2002)DOI: 10.1016/S0031-9422(02)00045-6
An 85-kDa β-glucosidase/xylosidase (BGX1) was purified from the axenically grown phytopathogenic oomycete, Phytophthora infestans. The bgx1 gene encodes a predicted 61-kDa protein product which, upon removal of a 21 amino acid leader peptide, accumulates in the apoplastic space. Extensive N-mannosylation accounts for part of the observed molecular mass difference. BGX1 belongs to family 30 of the glycoside hydrolases and is the first such oomycete enzyme deposited in public databases. The bgx1 gene was found in various Phytophthora species, but is apparently absent in species of the related genus, Pythium. Despite significant sequence similarity to human and murine lysosomal glucosylceramidases, BGX1 demonstrated neither glucocerebroside nor galactocerebroside-hydrolyzing activity. The native enzyme exhibited glucohydrolytic activity towards 4-methylumbelliferyl (4-MU) β-d-glucopyranoside and, to lesser extent, towards 4-MU-d-xylopyranoside, but not towards 4-MU-β-d-glucopyranoside. BGX1 did not hydrolyze carboxymethyl cellulose, cellotetraose, chitosan or xylan, suggesting high substrate specificity and/or specific cofactor requirements for enzymatic activity.A β-glucosidase/xylosidase was purified from the phytopathogenic oomycete, Phytophthora infestans. The encoding gene is the first such sequence reported from a species of the kingdom chromista.
Publikation
Keller, H.; Hohlfeld, H.; Wray, V.; Hahlbrock, K.; Scheel, D.; Strack, D.;Changes in the accumulation of soluble and cell wall-bound phenolics in elicitor-treated cell suspension cultures and fungus-infected leaves of Solanum tuberosumPhytochemistry42389-396(1996)DOI: 10.1016/0031-9422(95)00866-7
Cell suspension cultures of potato (Solanum tuberosum cv. Datura) treated with an elicitor preparation from Phytophthora infestans and potato leaves infected with the same fungus were used to study changes in the accumulation patterns of soluble and cell wall-bound phenolics. The compounds were identified by chromatographic comparison with authentic substances and by spectroscopic methods (FAB mass spectrometry, 1H and 13C NMR). The soluble phenolics were 4-O-β-glucopyranosylhydroquinone (arbutin), 4-O-β-glucopyranosylbenzoate, 3-methoxy-4-O-β-glucopyranosylbenzoate (vanillate glucoside), N-(E)-caffeoylputrescine, 2-O-β-glucopyranosylbenzoate (salicylate glucoside), N-(E)-feruloylputrescine, and N-(E)-feruloylaspartate. The cell wall-bound phenolics were 4-hydroxybenzoate, 4-hydroxybenzaldehyde, 3-methoxy-4-hydroxybenzaldehyde (vanillin), 4-(E)-coumarate, (E)-ferulate, N-4-(E)-coumaroyltyramine, and N-(E)-feruloyltyramine. The most prominent phenolics showing elicitor- or fungus-induced increases in accumulation rates were the soluble putrescine amides and cell wall-bound 4-hydroxybenzaldehyde and tyramine amides. In addition, there was a secretion of large amounts of coumaroyltyramine into the cell culture medium.