title: JASMONATE-INSENSITIVE1 encodes a MYC transcription factor essential to discriminate between different jasmonate-regulated defense responses in Arabidopsis.
abstract: In spite of the importance of jasmonates (JAs) as plant growth and stress regulators, the molecular components of their signaling pathway remain largely unknown. By means of a genetic screen that exploits the cross talk between ethylene (ET) and JAs, we describe the identification of several new loci involved in JA signaling and the characterization and positional cloning of one of them, JASMONATE-INSENSITIVE1 (JAI1/JIN1). JIN1 encodes AtMYC2, a nuclear-localized basic helix-loop-helix-leucine zipper transcription factor, whose expression is rapidly upregulated by JA, in a CORONATINE INSENSITIVE1-dependent manner. Gain-of-function experiments confirmed the relevance of AtMYC2 in the activation of JA signaling. AtMYC2 differentially regulates the expression of two groups of JA-induced genes. The first group includes genes involved in defense responses against pathogens and is repressed by AtMYC2. Consistently, jin1 mutants show increased resistance to necrotrophic pathogens. The second group, integrated by genes involved in JA-mediated systemic responses to wounding, is activated by AtMYC2. Conversely, Ethylene-Response-Factor1 (ERF1) positively regulates the expression of the first group of genes and represses the second. These results highlight the existence of two branches in the JA signaling pathway, antagonistically regulated by AtMYC2 and ERF1, that are coincident with the alternative responses activated by JA and ET to two different sets of stresses, namely pathogen attack and wounding.
authors.affiliation: Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Cientificas, Campus Universidad Autónoma, 28049 Madrid, Spain.
authors.forename: Oscar
authors.initials: O
authors.lastname: Lorenzo
authors.forename: Jose M
authors.initials: JM
authors.lastname: Chico
authors.forename: Jose J
authors.initials: JJ
authors.lastname: Sánchez-Serrano
authors.forename: Roberto
authors.initials: R
authors.lastname: Solano
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D003001:Cloning, Molecular; D003517:Cyclopentanes / Q000378:metabolism*; D004268:DNA-Binding Proteins; D005658:Fungi / Q000472:pathogenicity; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D054883:Oxylipins; D010940:Plant Proteins; D030821:Plants, Genetically Modified; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D003517:Cyclopentanes; D004268:DNA-Binding Proteins; C473611:MYC2 protein, Arabidopsis; C117206:MYC7E protein, Zea mays; D009687:Nuclear Proteins; D054883:Oxylipins; D010940:Plant Proteins; D016271:Proto-Oncogene Proteins c-myc; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C093680:ethylene-responsive element binding protein; C011006:jasmonic acid