Phenylpropanoids and long chain fatty acid derivatives in the interaction of Arabidopsis thaliana and Verticillium longisporum
Phenylpropanoide und langkettige Fettsäurederivate in der Interaktion von Arabidopsis thaliana und Verticillium longisporum
von Stefanie König geb. Götze
Datum der mündl. Prüfung:2011-10-14
Erschienen:2012-10-02
Betreuer:Prof. Dr. Ivo Feußner
Gutachter:Prof. Dr. Ivo Feußner
Gutachter:Prof. Dr. Wolfgang Dröge-Laser
Zum Verlinken/Zitieren:
http://dx.doi.org/10.53846/goediss-1456
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Zusammenfassung
Englisch
Verticillium longisporum is a soil borne pathogen which infects plants of the Brassicaceae family. The fungus enters through the roots and spreads within the plant through the xylem. Using the model plant Arabidopsis thaliana this thesis focused on metabolic changes accompanying the plant-fungus interaction. A metabolite fingerprinting approach was used to find metabolic changes in Arabidopsis upon infection. The most prominent markers that were identified derived from the phenylpropanoid pathway. Quantification of the phenylpropanoids by directed measurements could confirm the data of the non-targeted approach showing an accumulation of sinapoyl glucose, coniferin and diverse lignans already at early stages of infection. To test the contribution of the identified metabolic pathway on susceptibility of Arabidopsis against V. longisporum, different mutants of the phenylpropanoid pathway were analyzed. One of those was a ferulate-5-hydroxylase mutant (fah1-2) which is devoid of sinapate and its esters. This mutant showed a higher susceptibility towards the fungus, underlining the importance of the missing metabolites for the plant during infection. In addition a coniferin accumulation mutant (UGT72E2-OE) showed less stunting and more fungal DNA than wild type plants under infection. This effect might be due to fungal growth inhibiting properties of the deglucosylated coniferin or to an influence on fungal development of coniferin itself. Additionally implication of suberin and sphingolipids with α-hydroxy fatty acids in the infection was tested in this thesis. Suberin analyses at early time points of infection as well as infection of suberin mutants did not reveal any importance of this polymer in the infection. To investigate the functional significance of the α-hydroxylation in fatty acids of sphingolipids, T-DNA insertion mutants of both Fatty Acid Hydroxylase genes (AtFAH1 and AtFAH2) were analyzed in Arabidopsis. No phenotype was visible in the single mutant lines but the double mutant showed reduction in leaf size, root length and wrinkled leaves. Ceramide and glucosylceramide profiles of the double mutant showed a strong reduction of sphingolipids with α-hydroxylated fatty acid moieties and an accumulation of the one without hydroxy group. The total ceramide amount was ten times increased in the double mutant, whereas the glucosylceramide pool was 25 % reduced. Metabolite fingerprinting of the double mutant revealed differences compared to wild type in the metabolome. The most prominent markers were salicylic acid (SA) and its glucoside. Infection of the double mutant with powdery mildew resulted in less fungal colonization whereas infection with V. longisporum resulted in stronger stunting and slightly higher fungal DNA amount in infected plants. In summary it could be shown that the phenylpropanoid pathway is important for the defense response in Arabidopsis against V. longisporum but fatty acid monomers derived from suberin and sphingolipids seem to play no or only a minor role.
Keywords: Verticillium longisporum; Arabidopsis thaliana; phenylpropanoids; sphingolipids; fatty acid hydroxylase; suberin
Weitere Sprachen
Verticillium longisporum ist ein
bodenbürtiger, phytopathogener Pilz, der Pflanzen der Familie der
Brassicaceen befällt. Er dringt durch die Wurzel ein und verbreitet
sich in der Pflanze über das Xylem. In dieser Arbeit wurden die
metabolischen Veränderungen in der Modellpflanze Arabidopsis
thaliana während der Pflanzen-Pilz-Interaktion analysiert. Hierfür
wurde die
Schlagwörter: Verticillium longisporum; Arabidopsis thaliana; Phenylpropanoide; Sphingolipide; Fettsäure-Hydroxylase; Suberin