title: Identification and characterization of ANAC042, a transcription factor family gene involved in the regulation of camalexin biosynthesis in Arabidopsis.
abstract: Camalexin is the major phytoalexin in Arabidopsis. An almost complete set of camalexin biosynthetic enzymes have been elucidated but only limited information is available regarding molecular mechanisms regulating camalexin biosynthesis. Here, we demonstrate that ANAC042, a member of the NAM, ATAF1/2, and CUC2 (NAC) transcription factor family genes, is involved in camalexin biosynthesis induction. T-DNA insertion mutants of ANAC042 failed to accumulate camalexin at the levels achieved in the wild type, and were highly susceptible to Alternaria brassicicola infection. The camalexin biosynthetic genes CYP71A12, CYP71A13, and CYP71B15/PAD3 were not fully induced in the mutants, indicating that the camalexin defects were at least partly a result of reduced expression levels of these P450 genes. β-Glucuronidase (GUS)-reporter assays demonstrated tissue-specific induction of ANAC042 in response to differential pathogen infections. Bacterial flagellin (Flg22) induced ANAC042 expression in the root-elongation zone, the camalexin biosynthetic site, and the induction was abolished in the presence of either a general kinase inhibitor (K252a), a Ca(2+)-chelator (BAPTA), or methyl jasmonate. The GUS-reporter assay revealed repression of the Flg22-dependent ANAC042 expression in the ethylene-insensitive ein2-1 background but not in sid2-2 plants defective for salicylic acid biosynthesis. We discuss ANAC042 as a key transcription factor involved in previously unknown regulatory mechanisms to induce phytoalexin biosynthesis in Arabidopsis.
authors.affiliation: Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Saga
authors.forename: Takumi
authors.initials: T
authors.lastname: Ogawa
authors.forename: Kosuke
authors.initials: K
authors.lastname: Kai
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ogata
authors.forename: Nozomu
authors.initials: N
authors.lastname: Sakurai
authors.forename: Daisuke
authors.initials: D
authors.lastname: Shibata
authors.forename: Daisaku
authors.initials: D
authors.lastname: Ohta
mesh_terms: D000528:Alternaria / Q000502:physiology*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D016922:Cellular Senescence; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D007211:Indoles / Q000378:metabolism*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000382:microbiology; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000382:microbiology; D011993:Recombinant Fusion Proteins; D016415:Sequence Alignment; D012717:Sesquiterpenes / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D013844:Thiazoles / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome; D000094162:Phytoalexins
chemical_list: C588250:ANAC042 protein, Arabidopsis; D029681:Arabidopsis Proteins; D007211:Indoles; D011993:Recombinant Fusion Proteins; D012717:Sesquiterpenes; D013844:Thiazoles; D014157:Transcription Factors; C102405:camalexin; D049452:Green Fluorescent Proteins; D000094162:Phytoalexins