Verticillium longisporum induced changes in the extracellular compartment in Arabidopsis thaliana and Brassica napus
Final Report Abstract
Proteomic studies of Arabidopsis thaliana obtained during phase I of this Research Unit revealed that three different peroxidases, a serine-carboxypeptidase, an α-galactosidase and a germin-like protein (GLP3) were more abundant in the apoplast of infected than in that of uninfected plants, whereas a lectin-like protein was decreased under these conditions. The main aim of the present study was to functionally characterize these differentially expressed extracellular proteins in relation to physiological and anatomical alterations induced by VL. Growth experiments of VL in extracellular fluids showed that proteins restricted fungal growth. To investigate which proteins were responsible for the immune response against V. longisporum in A. thaliana, functional analyses were performed. For this purpose, homozygous plants of T-DNA insertion lines were isolated and challenged with V. longisporum. Most of them displayed a pathophenotype similar to that of the wild-type. However, Arabidopsis lines with reduced expression of the germin-like protein 3 (GLP3) showed enhanced susceptibility to VL. amiRNA lines for GLP3 supported these results. Moreover, GLP3-overexpressing plants showed less disease symptoms than the wild-type. This correlated with reduced amounts of fungal DNA within the GLP3-overexpressing plants and increased fungal DNA in T-DNA insertion lines. Growth experiments with GLP3 expressed in yeast showed that the protein was able to attenuate proliferation of V. longisporum in vitro. The results indicate that GLP3 mediates resistance in A. thaliana by restricting the growth of the fungus directly. The molecular mechanisms of GLP3 action is unclear and should be investigated in further experiments. Since some of the differentially expressed candidate proteins in A. thaliana may have functions in cell wall remodelling infected and mock inoculated plants were investigated anatomically. Infection with V. longisporum led to the production of hyperplastic xylem in the hypocotyl as well as in leaf petioles. Moreover, transdifferentiation of mesophyll cells into xylem vessels was observed in leaves. The biological role of these modifications is currently actively investigated in collaboration with other groups of this research unit.
Publications
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(2007) Identifizierung und Charakterisierung extrazellulärer Proteine unter dem Einfluss von Verticillium longisporum in Arabidopsis thaliana und Raps (Brassica napus). Göttingen, Univ., Diss., Online Ressource (129 S.)
Saskia Flörl
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(2008) Defence reactions in the apoplastic proteome of oilseed rape (Brassica napus var. napus) attenuate Verticillium longisporum growth but not disease symptoms. BMC Plant Biology 8:129
Floerl S, Drübert C, Majcherczyk A, Karlovsky P, Kües U, Polle A
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(2010) Disease symptoms and mineral nutrition in Arabidopsis thaliana in response to Verticillium longisporum VL43 infection. Journal of Plant Pathology 92 (3): 695-702
Floerl S, Druebert C, Aroud HI, Karlovsky P, Polle A
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(2010) Silencing of VLARO2 for chorismate synthase revealed that the phytopathogen Verticillium longisporum induces the amino acid cross-pathway control during growth in the plant xylem. Applied Microbiology and Biotechnology 85, 1961-1976
Singh S, Braus-Stromeyer SA, Lohaus G, Reusche M, Knüfer M, Teichmann T, von Tiedemann A, Braus GH
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(2011) Funktionelle Charakterisierung von apoplastischen Proteinen in Brassica napus und Arabidopsis thaliana nach Infektion mit Verticillium longisporum. Göttingen, Univ., Diss., Online-Ressource (PDF-Datei: 208 S.)
Christine Drübert
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(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. Molecular Plant Microbe Interaction 25, 569-581
Singh S, Braus-Stromeyer SA, Timpner C, Valerius O, von Tiedemann A, Karlovsky P, Druebert C, Polle A, Braus GH
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(2012) The vascular pathogen Verticillium longisporum requires a jasmonic acid-independent COI1 function in roots to elicit disease symptoms in Arabidopsis thaliana shoots. Plant Phys.
Ralhan A, Schöttle S, Thurow, C, Iven T, Feußner I, Polle A, Gatz C
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(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
