title: Regulation of Pathogen-Triggered Tryptophan Metabolism in Arabidopsis thaliana by MYB Transcription Factors and Indole Glucosinolate Conversion Products.
abstract: MYB34, MYB51, and MYB122 transcription factors are known as decisive regulators of indolic glucosinolate (IG) biosynthesis with a strong impact on expression of genes encoding CYP79B2 and CYP79B3 enzymes that redundantly convert tryptophan to indole-3-acetaldoxime (IAOx). This intermediate represents a branching point for IG biosynthesis, and pathways leading to camalexin and indole-carboxylic acids (ICA). Here we investigate how these MYBs affect the pathogen-triggered Trp metabolism. Our experiments indicated that these three MYBs affect not only IG production but also constitutive biosynthesis of other IAOx-derived metabolites. Strikingly, the PENETRATION 2 (PEN2)-dependent IG-metabolism products, which are absent in myb34/51/122 and pen2 mutants, were indispensable for full flg22-mediated induction of other IAOx-derived compounds. However, gene induction and accumulation of ICAs and camalexin upon pathogen infection was not compromised in myb34/51/122 plants, despite strongly reduced IG levels. Hence, in comparison with cyp79B2/B3, which lacks all IAOx-derived metabolites, we found myb34/51/122 an ideal tool to analyze IG contribution to resistance against the necrotrophic fungal pathogen Plectosphaerella cucumerina. The susceptibility of myb34/51/122 was similar to that of pen2, but much lower than susceptibility of cyp79B2/B3, indicating that MYB34/51/122 contribute to resistance toward P. cucumerina exclusively through IG biosynthesis, and that PEN2 is the main leaf myrosinase activating IGs in response to microbial pathogens.
authors.affiliation: Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, BioCenter, Zülpicher Straße 47b, 50674 Cologne, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Frerigmann
authors.affiliation: Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego12/14, 61-704 Poznań, Poland.
authors.forename: Mariola
authors.initials: M
authors.lastname: Piślewska-Bednarek
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus Montegancedo, Pozuelo de Alarcón, 28223 Madrid, Spain.
authors.forename: Andrea
authors.initials: A
authors.lastname: Sánchez-Vallet
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus Montegancedo, Pozuelo de Alarcón, 28223 Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Molina
authors.affiliation: Lehrstuhl für Genetik, Technische Universität München, Emil-Ramann-Str. 8, 85354 Freising, Germany.
authors.forename: Erich
authors.initials: E
authors.lastname: Glawischnig
authors.affiliation: Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, BioCenter, Zülpicher Straße 47b, 50674 Cologne, Germany.
authors.forename: Tamara
authors.initials: T
authors.lastname: Gigolashvili
authors.affiliation: Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego12/14, 61-704 Poznań, Poland. Electronic address: bednarek@ibch.poznan.pl.
authors.forename: Paweł
authors.initials: P
authors.lastname: Bednarek
mesh_terms: D017360:Arabidopsis / Q000378:metabolism* / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001203:Ascomycota / Q000472:pathogenicity; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007211:Indoles / Q000378:metabolism; D009699:N-Glycosyl Hydrolases / Q000378:metabolism; D010091:Oximes / Q000378:metabolism; D057865:Plant Immunity / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D007211:Indoles; C000595373:MYB122 protein, Arabidopsis; C000595372:MYB34 protein, Arabidopsis; C000602970:MYB36 protein, Arabidopsis; C523452:MYB51 protein, Arabidopsis; D010091:Oximes; D014157:Transcription Factors; C467098:indole-3-acetaldoxime; D014364:Tryptophan; D003577:Cytochrome P-450 Enzyme System; C530432:cytochrome P-450 79B2 protein, Arabidopsis; C471054:cytochrome P-450 CYP79B3, Sinapis alba; D009699:N-Glycosyl Hydrolases; C505663:PEN2 protein, Arabidopsis
keywords: MAMP-triggered immunity; Plectosphaerella cucumerina; Trp metabolism; camalexin; indole-3-carboxylic acids; indolic glucosinate