Transcriptional Activation and Production of Tryptophan-Derived Secondary Metabolites in Arabidopsis Roots Contributes to the Defense against the Fungal Vascular Pathogen Verticillium Iongisporum  

作　　者：Tim Iven Stefanie Konig Seema Singh Susanna A. Braus-Stromeyer Matthias Bischoff Lutz F. Tietze Gerhard H. Braus Volker Lipka Ivo Feussner Wolfgang Droge-Laser 

机构地区：[1]Julius-Maximilians-Universitat Wurzburg, Julius-von-Sachs-lnstitut, Pharmazeutische Biologie, Julius-von-Sachs-Platz 2, 97082 Wurzburg, Germany [2]Georg-August-Universitat, Albrecht-von-Haller-lnstitut fur Pflanzenwissenschaften, Biochemie der Pflanze, Justus-von-Liebig-Weg 11, 37077 Gottingen,Germany [3]Georg-August-Universitat, Institut for Mikrobiologie und Genetik, Molekulare Mikrobiologie und Genetik, Grisebachstr. 8, 37077 Gottingen, Germany [4]Georg-August-Universitat, Institut for Organische und Biomolekulare Chemie, AG Tietze, Tammannstrasse 2, 37077 Gottingen, Germany [5]Georg-August-Universitat, Schwann-Schleiden-Forschungszentrum for Molekulare Zellbiologie, Abteilung Zellbiologie der Pflanze, Julia-Lermontowa-Weg3, 37077 Gottingen, Germany

出　　处：《Molecular Plant》2012年第6期1389-1402,共14页分子植物（英文版）

摘　　要：The soil-borne fungal pathogen Verticillium Iongisporum causes vascular disease on Brassicaceae host plants such as oilseed rape. The fungus colonizes the root xylem and moves upwards to the foliage where disease symptoms become visible. Using Arabidopsis as a model for early gene induction, we performed root transcriptome analyses in re- sponse to hyphal growth immediately after spore germination and during penetration of the root cortex, respectively. Infected roots showed a rapid reprogramming of gene expression such as activation of transcription factors, stress-, and defense-related genes. Here, we focused on the highly coordinated gene induction resulting in the production of tryp- tophan-derived secondary metabolites. Previous studies in leaves showed that enzymes encoded by CYP81F2 and PEN2 （PENETRATION2） execute the formation of antifungal indole glucosinolate （IGS） metabolites. In Verticillium-infected roots, we found transcriptional activation of CYP81F2 and the PEN2 homolog PEL 1 （PEN2-LIKE1）, but no increase in antifungal IGS breakdown products. In contrast, indole-3-carboxylic acid （13CA） and the phytoalexin camalexin accumulated in infected roots but only camalexin inhibited Verticillium growth in vitro. Whereas genetic disruption of the individual metabolic pathways leading to either camalexin or CYP81F2-dependent IGS metabolites did not alter Verticillium-induced disease symptoms, a cyp79b2 cyp79b3 mutant impaired in both branches resulted in significantly enhanced susceptibility. Hence, our data provide an insight into root-specific early defenses and suggest tryptophan-derived metabolites as active anti- fungal compounds against a vascular pathogen.The soil-borne fungal pathogen Verticillium Iongisporum causes vascular disease on Brassicaceae host plants such as oilseed rape. The fungus colonizes the root xylem and moves upwards to the foliage where disease symptoms become visible. Using Arabidopsis as a model for early gene induction, we performed root transcriptome analyses in re- sponse to hyphal growth immediately after spore germination and during penetration of the root cortex, respectively. Infected roots showed a rapid reprogramming of gene expression such as activation of transcription factors, stress-, and defense-related genes. Here, we focused on the highly coordinated gene induction resulting in the production of tryp- tophan-derived secondary metabolites. Previous studies in leaves showed that enzymes encoded by CYP81F2 and PEN2 （PENETRATION2） execute the formation of antifungal indole glucosinolate （IGS） metabolites. In Verticillium-infected roots, we found transcriptional activation of CYP81F2 and the PEN2 homolog PEL 1 （PEN2-LIKE1）, but no increase in antifungal IGS breakdown products. In contrast, indole-3-carboxylic acid （13CA） and the phytoalexin camalexin accumulated in infected roots but only camalexin inhibited Verticillium growth in vitro. Whereas genetic disruption of the individual metabolic pathways leading to either camalexin or CYP81F2-dependent IGS metabolites did not alter Verticillium-induced disease symptoms, a cyp79b2 cyp79b3 mutant impaired in both branches resulted in significantly enhanced susceptibility. Hence, our data provide an insight into root-specific early defenses and suggest tryptophan-derived metabolites as active anti- fungal compounds against a vascular pathogen.

关 键 词：Verticillium Iongisporum Arabidopsis root transcriptome CAMALEXIN indole glucosinolates. 

分 类 号：S763[农业科学—森林保护学] Q946.8[农业科学—林学]