Wissenschaftliche Highlights der GSF 2007

Transcription

1 H Forschungszentrum für Umwelt und Gesundheit GmbH in der Helmholtzgemeinschaft Wissenschaftlich-Technische Abteilung Wissenschaftliche Highlights der GSF 2007 Abfrage April 2007 Institut / Selbst. Abteilung / KKG / Nachwuchsgruppe: FE-Nr.: Kontaktperson für Rückfragen: Prof. Dr. Peter Schröder, peter.schroeder@gsf.de, 4056 Titel des Highlights: Uptake, degradation and chiral discrimination of N-Acyl-D/L-homoserine lactones by barley and yam bean plants Keywords: N-Acyl-D/L-homoserine lactone; Hordeum vulgare; Pachyrhizus erosus; plant-microbe interaction; quorum sensing Kernaussage des Highlights in einem Satz: Two plant species showed different abilities to take up N-Acyl-D/L-homoserine lactones with different structures into roots and shoots as well as to discriminate the respective stereoisomers. Darstellung des Highlights: Bacteria colonizing plant roots communicate via small signalling substances. In gramnegative bacteria, this so-called quorum sensing uses molecules of the N-acyl-homoserine lactones (AHL) type. The aim of the present study was to examine how efficient different plants are able to take up bacterial signalling compounds in order to react with specific responses. Since plants are naturally exposed to a huge diversity of bacterial species from beneficial to harmless as well as pathogenic bacteria, sensing and reacting towards AHL exposure might provide a certain advance to plants by enabling them to modify their defence mechanisms according to the kind of signal they encounter. Barley (Hordeum vulgare L.) and the tropical legume yam bean (Pachyrhizus erosus (L.) Urban) were chosen as representative mono- or dicotyledoneous plants. We demonstrated that the presence of plants enhanced AHL decline in media with higher degradative activity 1

2 of the legume. The uptake and translocation of AHLs into roots and shoots was examined by UPLC, FTICR-MS and radiotracing Tritium-labelled compounds. The translocation process into the shoot strongly depends on the lipophilic features of AHLs. Furthermore, it turned out that both plants, when supplied with a racemic mixture of D- and L-AHLs, discriminated D- AHLs in favour of the biologically active L-isomer. Again, the legume yam bean, which is naturally exposed to AHL-producers in their symbiosis with root-nodulating bacteria, reacted more strongly than barley. These results indicate fundamental differences in AHL turnover between different plant species and AHLs. Götz C, Fekete A, Gebefuegi I, Forczek ST, Fuksová K, Li X, Englmann M, Gryndler M, Hartmann A, Matucha M, Schmitt-Kopplin P and Schröder P Uptake, degradation and chiral discrimination of N-Acyl-D/L-homoserine lactones by barley (Hordeum vulgare) and yam bean (Pachyrhizus erosus) plants in consideration of abiotic factors. Plant Physiology, submitted. Bezug zur GSF-Strategie: Understanding the plants reactions towards bacterial communication might represent a key factor in the development of future plant protection techniques to ensure healthy food production combined with minimized contamination of the environment. GSF-interne Kooperationspartner, mit denen das Highlight ggf. erarbeitet wurde: Institute of Ecological Chemistry, Prof. Dr. Schmitt-Kopplin Externe Partner: Academy of Sciences of the Czech Republic, Prague, Dr. M. Matucha 2

3 Uptake, degradation and chiral discrimination of N- Acyl-D/L-homoserine lactones by barley and yam bean plants Götz C, Fekete A, Gebefuegi I, Forczek ST*, Fuksová K*, Li X, Englmann M, Gryndler M*, Hartmann A, Matucha M*, Schmitt-Kopplin P and Schröder P. (2007). GSF-Institute of Ecological Chemistry, *Academy of Sciences of the Czech Republic, Prague

4 Bacterial AHL-signal molecules aretakenup differentlybyplants(1) Barley, (Hordeum vulgare ) Yam bean, (Pachyrhizus erosus ) H N R N-Acyl homoserine lactone AHL Uptake of AHL-molecules with different structures (R= C6-, C8- and C10) into plant roots and shoots was tested in axenic plant systems AHL-uptake into the plant roots and shoots depends on: Plant species (Yam bean > barley) Length of AHL carbon side chain (C6, C8 or C10-HSL) AHLs bearing longer side chains are less efficiently translocated, at least not in unaltered structure AHL uptake occurs rapidly. Radioactively labelled AHLs are detectable in roots and shoots in less than 4 hours after application.

5 Bacterial AHL-signal molecules are found in barley shoots, but not in yam bean (2) AHL-compounds are taken up into the shoots of barley plants more efficiently as in the leguminous yam bean plant, which degrade AHLs efficiently. Plants actively interfere with AHL uptake by discriminating D-isomers in favor of biologically active L-isomers a= control shoot Conclusion: Fundamental differences in signal molecule turnover depending on plant species and AHL structure were proven in these experiments, which help elucidating our understanding of microbe-plant- interactions in the rhizosphere. Control b= shoot + AHL c= control root d= root +AHL Yam bean C8-HSL e= stand. AHL determination in roots and shoots of barley (FTICR-MS) Chiral discrimination of D-AHL in yam bean