Expression profiling in Brassica napus L. infected with Verticililium longisporum
Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems
Final Report Abstract
The quantitative non-targeted transcript profiling in plant tissues subjected to different stages of VL infection yielded a largely similar level of overall gene expression, however, a specific set of genes regulated by local or systemic effects of VL infection was differentiated. Tissues with high levels of fungal colonization were more responsive on the transcriptome level than apparently „pathogen-free‟ tissues in inoculated plants. Levels of SA and its glucoside SAG were significantly increased in stem parenchyma and xylem sap of VL infected plants, while JA was unaffected and ABA only slightly enhanced. Accordingly, activity of SA related defense genes like PR-1 and PR-3 were significantly enhanced while PDF1.2 related to JA/ET signaling was poorly responsive. This role of SA signaling was corroborated by a strongly enhanced disease phenotype in nahG transgenic B. napus plants compromised in their ability to accumulate SA. In addition to elevated SA/SAG levels, VL infected plants had a silenced level of ROS (H2O2,), suggesting a biotrophic status during initial disease stages. Preinoculative soil drench application of BABA (ß-aminobutyric acid) induced resistance in B. napus to VL infection, which did not inhibit root colonization but significantly reduced growth and spread of the pathogen in the hypocotyl and shoot. BABA induced resistance was associated with enhanced PAL activity and excessive formation of phenol-storing xylem parenchyma cells in the colonized hypocotyls which were not observed without BABA priming. Although pathogen elevated SA levels in B. napus did not completely suppress pathogen growth SA is considered a crucial factor of basal resistance slowing down colonization of B. napus with VL. Since BABA induced resistance is similar to genotypic resistance it is suggested that it is based on priming and enhancement of natural resistance mechanisms. VL preinoculated B. napus plants were differentially altered in their response to two necrotrophic shoot pathogens. The partial suppression of lesion growth induced by S. sclerotiorum compared to no effect on infection with Phoma lingam needs further elucidation.
Publications
-
Beteiligung systemischer Signale an der Symptomauslösung bei Brassica napus nach Infektion mit Verticillium longisporum und V. dahliae. PhD thesis
Nadine Riediger
-
(2009) Internal resistance in winter oilseed rape inhibits systemic spread of the vascular pathogen Verticillium longisporum. Phytopathology, 99(7), 802-811
Eynck, C., B. Koopmann, P. Karlovsky, A. v. Tiedemann
-
(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., N. Riediger, A.v. Tiedemann, P. 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 (6), 1961-1976
Singh S., S. A. Braus-Stromeyer, C. Timpner, G. Lohaus, Van Tuan Tran, M. Reusche, J. Knüfer, T. Teichmann, A.v. Tiedemann & G.H. Braus
-
(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
