title: TRANSCRIPTION ACTIVATOR-LIKE EFFECTOR NUCLEASE-Mediated Generation and Metabolic Analysis of Camalexin-Deficient cyp71a12 cyp71a13 Double Knockout Lines.
abstract: In Arabidopsis (Arabidopsis thaliana), a number of defense-related metabolites are synthesized via indole-3-acetonitrile (IAN), including camalexin and indole-3-carboxylic acid (ICOOH) derivatives. Cytochrome P450 71A13 (CYP71A13) is a key enzyme for camalexin biosynthesis and catalyzes the conversion of indole-3-acetaldoxime (IAOx) to IAN. The CYP71A13 gene is located in tandem with its close homolog CYP71A12, also encoding an IAOx dehydratase. However, for CYP71A12, indole-3-carbaldehyde and cyanide were identified as major reaction products. To clarify CYP71A12 function in vivo and to better understand IAN metabolism, we generated two cyp71a12 cyp71a13 double knockout mutant lines. CYP71A12-specific transcription activator-like effector nucleases were introduced into the cyp71a13 background, and very efficient somatic mutagenesis was achieved. We observed stable transmission of the cyp71a12 mutation to the following generations, which is a major challenge for targeted mutagenesis in Arabidopsis. In contrast to cyp71a13 plants, in which camalexin accumulation is partially reduced, double mutants synthesized only traces of camalexin, demonstrating that CYP71A12 contributes to camalexin biosynthesis in leaf tissue. A major role of CYP71A12 was identified for the inducible biosynthesis of ICOOH. Specifically, the ICOOH methyl ester was reduced to 12% of the wild-type level in AgNO3-challenged cyp71a12 leaves. In contrast, indole-3-carbaldehyde derivatives apparently are synthesized via alternative pathways, such as the degradation of indole glucosinolates. Based on these results, we present a model for this surprisingly complex metabolic network with multiple IAN sources and channeling of IAOx-derived IAN into camalexin biosynthesis. In conclusion, transcription activator-like effector nuclease-mediated mutation is a powerful tool for functional analysis of tandem genes in secondary metabolism.
authors.affiliation: Lehrstuhl für Genetik, Technische Universität München, 85354 Freising, Germany (T.M.M., C.C.G., J.L., E.G.);Julius Kühn-Institut, Institut für Ökologische Chemie, Pflanzenanalytik, und Vorratsschutz, 14195 Berlin, Germany (C.B.); andCenter for Plant Molecular Biology-General Genetics, University of Tübingen, 72076 Tuebingen, Germany (R.M., T.L.).
authors.forename: Teresa M
authors.initials: TM
authors.lastname: Müller
authors.affiliation: Lehrstuhl für Genetik, Technische Universität München, 85354 Freising, Germany (T.M.M., C.C.G., J.L., E.G.);Julius Kühn-Institut, Institut für Ökologische Chemie, Pflanzenanalytik, und Vorratsschutz, 14195 Berlin, Germany (C.B.); andCenter for Plant Molecular Biology-General Genetics, University of Tübingen, 72076 Tuebingen, Germany (R.M., T.L.).
authors.forename: Christoph
authors.initials: C
authors.lastname: Böttcher
authors.affiliation: Lehrstuhl für Genetik, Technische Universität München, 85354 Freising, Germany (T.M.M., C.C.G., J.L., E.G.);Julius Kühn-Institut, Institut für Ökologische Chemie, Pflanzenanalytik, und Vorratsschutz, 14195 Berlin, Germany (C.B.); andCenter for Plant Molecular Biology-General Genetics, University of Tübingen, 72076 Tuebingen, Germany (R.M., T.L.).
authors.forename: Robert
authors.initials: R
authors.lastname: Morbitzer
authors.affiliation: Lehrstuhl für Genetik, Technische Universität München, 85354 Freising, Germany (T.M.M., C.C.G., J.L., E.G.);Julius Kühn-Institut, Institut für Ökologische Chemie, Pflanzenanalytik, und Vorratsschutz, 14195 Berlin, Germany (C.B.); andCenter for Plant Molecular Biology-General Genetics, University of Tübingen, 72076 Tuebingen, Germany (R.M., T.L.).
authors.forename: Cornelia C
authors.initials: CC
authors.lastname: Götz
authors.affiliation: Lehrstuhl für Genetik, Technische Universität München, 85354 Freising, Germany (T.M.M., C.C.G., J.L., E.G.);Julius Kühn-Institut, Institut für Ökologische Chemie, Pflanzenanalytik, und Vorratsschutz, 14195 Berlin, Germany (C.B.); andCenter for Plant Molecular Biology-General Genetics, University of Tübingen, 72076 Tuebingen, Germany (R.M., T.L.).
authors.forename: Johannes
authors.initials: J
authors.lastname: Lehmann
authors.affiliation: Lehrstuhl für Genetik, Technische Universität München, 85354 Freising, Germany (T.M.M., C.C.G., J.L., E.G.);Julius Kühn-Institut, Institut für Ökologische Chemie, Pflanzenanalytik, und Vorratsschutz, 14195 Berlin, Germany (C.B.); andCenter for Plant Molecular Biology-General Genetics, University of Tübingen, 72076 Tuebingen, Germany (R.M., T.L.).
authors.forename: Thomas
authors.initials: T
authors.lastname: Lahaye
authors.affiliation: Lehrstuhl für Genetik, Technische Universität München, 85354 Freising, Germany (T.M.M., C.C.G., J.L., E.G.);Julius Kühn-Institut, Institut für Ökologische Chemie, Pflanzenanalytik, und Vorratsschutz, 14195 Berlin, Germany (C.B.); andCenter for Plant Molecular Biology-General Genetics, University of Tübingen, 72076 Tuebingen, Germany (R.M., T.L.) egl@wzw.tum.de.
authors.forename: Erich
authors.initials: E
authors.lastname: Glawischnig
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001483:Base Sequence; D003577:Cytochrome P-450 Enzyme System / Q000172:deficiency* / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000378:metabolism*; D055786:Gene Knockout Techniques; D007211:Indoles / Q000378:metabolism*; D040582:Inheritance Patterns / Q000235:genetics; D055432:Metabolomics; D008954:Models, Biological; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010091:Oximes / Q000378:metabolism; D064210:Secondary Metabolism; D013844:Thiazoles / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D000094162:Phytoalexins
chemical_list: D029681:Arabidopsis Proteins; D003577:Cytochrome P-450 Enzyme System; D003851:Deoxyribonucleases; D007211:Indoles; D010091:Oximes; D013844:Thiazoles; D015534:Trans-Activators; C102405:camalexin; D000094162:Phytoalexins; C467098:indole-3-acetaldoxime; C016516:indole-3-acetonitrile; C000606222:cytochrome P-450 71A12, Arabidopsis; C523448:cytochrome P-450 71A13 protein, Arabidopsis