FOR 546: Analyse der systemischen Wirkung von Infektionen wurzelbürtiger Pilze auf ausgewählte Brassicaceen unter Berücksichtigung von multitrophen Interaktionen mit Insekten und mikrobiellen Pathogenen
Agrar-, Forstwissenschaften und Tiermedizin
Zusammenfassung der Projektergebnisse
Verticillium longisporum (VL) is an interesting model system for understanding the biology of a vascular pathogen both in its natural host (Brassica napus) and in the model plant Arabidopsis thaliana. The ultimate goal of research unit FOR546 was to understand the interaction between both organisms at the molecular level, both in the roots, where the fungus invades the plant, and the xylem, where the fungus proliferates. Basal methods and tools (growth conditions, infections, quantification of fungal DNA, cDNA-AFLP, metabolomics, transgenic fungi and plants) were established. Interaction-induced responses of the plant and the fungus were described, covering physiological parameters like water status and photosynthesis, anatomical analyses and the identification of interaction-induced proteins, transcripts and metabolites. Arabidopsis thaliana. VL invades unwounded Arabidopsis roots, which in turn synthesize antimicrobial secondary metabolites that derive from tryptophan. The fungus overcomes this layer of defense and colonizes the xylem. Later, proliferation and formation of microsclerotia in the shoot depends on the induction of premature senescence which leads to the mobilization of nutrients and their subsequent transport into the vascular bundle. The water status and the efficiency of photosynthesis are not significantly altered in infected plants demonstrating that plant responses are rather due to regulatory cues than to occlusion of vessels. Induction of senescence requires the jasmonate receptor COI1 in roots. Unexpectedly, this senescencepromoting function of COI1 is independent from any jasmonate-related ligand. Possible mechanisms how these root-borne processes promote senescence are degradation of cytokinins or up-regulation of the ethylene pathway. In addition, VL synthesizes toxins and harmful proteins that might contribute to the leakage of metabolites into the xylem. Fungal infections induce transdifferentiation of bundle sheath and phloem cells into xylem vessels which help the plant to persist drought stress. The formation of more lignified cells is associated with the transcriptional activation of the phenylpropanoid pathway. Although the plant defense hormones salicylic acid and jasmonic acid are induced after fungal infection, the corresponding defense responses are not effective. An anti-fungal Germin-Like Protein (GLP3) accumulates in the apoplast . Mapping studies using the susceptible ecotype Landsberg erecta and the more resistant ecotype Burren pointed at several QTLs and the ERECTA locus to confer resistance. Brassica napus. The xylem sap of B. napus contains antifungal proteins, the phytoalexin cyclobrassinin as well as the defense hormone salicylic acid (SA) and its glucoside (SAG). Preliminary studies indicate that the SA pathway confers some level of resistance, which restricts fungal propagation in the hypocotyl. Moreover, the xylem sap contains regulatory signals that promote fungal growth. Verticillium longisporum. The fungus has to adapt to the nutrient-poor and anti-fungal conditions in the xylem. In planta up-regulation of anti-oxidative enzymes, regulators of amino acid synthesis, necrosis and ethylene-inducing peptides (NEPs) have been shown to support fungal performance in planta. Moreover, other proteins of unknown function were detected. Candidate regulatory factors which might control fungal adhesion to the plant surface were identified.
Projektbezogene Publikationen (Auswahl)
- (2007) In planta ORFeome analysis by large-scale over-expression of GATEWAY-compatible cDNA clones: screening of ERF transcription factors involved in abiotic stress defense. Plant J 52, 382-390
Weiste C, Iven T, Fischer U, Onate-Sanchez L, Dröge-Laser W
- (2008) Defence reactions in the apoplastic proteome of oilseed rape (Brassica napus var. napus) attenuate Verticillium longisporum growth but not disease symptoms. BMC Plant Biol 8, 129-144
Floerl S, Druebert C, Majcherczyk A, Karlovsky P, Kües U, Polle A
- (2008) Improved coverage of cDNA-AFLP by sequential digestion of immobilized cDNA. BMC Genomics 9, 480-495
Weiberg A, Pöhler D, Morgenstern B, Karlovsky P
- (2009) Components of variance in transcriptomics based on electrophoretic separation of cDNA fragments (cDNA-AFLP). Electrophoresis 30, 2549–2557
Weiberg A, Karlovsky P
- (2009) Internal resistance in winter oilseed rape inhibits systemic spread of the vascular pathogen Verticillium longisporum. Phytopathology 99(7), 802-811
Eynck C, Koopmann B, Karlovsky P, Tiedemann A
- (2009) Salicylic acid and salicylic acid glucoside in xylem sap of Brassica napus infected with Verticillium longisporum. J Plant Research 122, 571-579
Ratzinger A , Riediger N, Tiedemann A, Karlovsky
- (2009) Silencing of Vlaro2 for chorismate synthase revealed that the phytopathogen Verticillium longisporum induces the cross-pathway control in the xylem. Appl Microbiol Biotechnol 85, 1961-1976
Singh S, Braus-Stromeyer SA, Timpner C, Lohaus G, Tran VT, Reusche R, Knüfer J, Teichmann T, Tiedemann A, Braus GH
- (2010) Disease symptoms and mineral nutrition in Arabidopsis thaliana in response to Verticillium longisporum VL43 infection. Journal of Plant Pathology 92, 695-702
Floerl S, Druebert C, Aroud HI, Karlovsky P, Polle A
- (2010) Genetic and environmental control of the Verticillium syndrome in Arabidopsis thaliana. BMC Plant Biol 10, 235-250
Häffner E, Karlovsky P, Diederichsen E
- (2012) The plant host Brassica napus induces in the pathogen Verticillium longisporum the expression of functional catalase peroxidase which is required for the late phase of disease. Mol Plant Microbe Interact 25, 569-581
Singh S, Braus-Stromeyer SA, Timpner C, Valerius O, von Tiedemann A, Karlovsky P, Druebert C, Polle A, Braus GH
(Siehe online unter https://doi.org/10.1094/MPMI-08-11-0217) - (2012) Transcriptional activation and production of tryptophanderived secondary metabolites in Arabidopsis roots contributes to the defense against the fungal vascular pathogen Verticillium longisporum. Mol Plant
Iven T, Konig S, Singh S, Braus-Stromeyer SA, Bischoff M, Tietze LF, Braus GH, Lipka V, Feussner F, Droge-Laser W
(Siehe online unter https://doi.org/10.1093/mp/sss044) - (2012) Verticillium longisporum infection affects the leaf apoplastic proteome, metabolome and cell wall properties in Arabidopsis thaliana. Plos One 2,e31435
Floerl S, Majcherczyk A, Possienke M, Feussner K, Tappe H, Gatz C, Feussner I, Kües U, Polle A
(Siehe online unter https://doi.org/10.1371/journal.pone.0031435)
