title: The Arabidopsis bHLH transcription factors MYC3 and MYC4 are targets of JAZ repressors and act additively with MYC2 in the activation of jasmonate responses.
abstract: Jasmonates (JAs) trigger an important transcriptional reprogramming of plant cells to modulate both basal development and stress responses. In spite of the importance of transcriptional regulation, only one transcription factor (TF), the Arabidopsis thaliana basic helix-loop-helix MYC2, has been described so far as a direct target of JAZ repressors. By means of yeast two-hybrid screening and tandem affinity purification strategies, we identified two previously unknown targets of JAZ repressors, the TFs MYC3 and MYC4, phylogenetically closely related to MYC2. We show that MYC3 and MYC4 interact in vitro and in vivo with JAZ repressors and also form homo- and heterodimers with MYC2 and among themselves. They both are nuclear proteins that bind DNA with sequence specificity similar to that of MYC2. Loss-of-function mutations in any of these two TFs impair full responsiveness to JA and enhance the JA insensitivity of myc2 mutants. Moreover, the triple mutant myc2 myc3 myc4 is as impaired as coi1-1 in the activation of several, but not all, JA-mediated responses such as the defense against bacterial pathogens and insect herbivory. Our results show that MYC3 and MYC4 are activators of JA-regulated programs that act additively with MYC2 to regulate specifically different subsets of the JA-dependent transcriptional response.
authors.affiliation: Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, 28049 Madrid, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Fernández-Calvo
authors.forename: Andrea
authors.initials: A
authors.lastname: Chini
authors.forename: Gemma
authors.initials: G
authors.lastname: Fernández-Barbero
authors.forename: José-Manuel
authors.initials: JM
authors.lastname: Chico
authors.forename: Selena
authors.initials: S
authors.lastname: Gimenez-Ibanez
authors.forename: Jan
authors.initials: J
authors.lastname: Geerinck
authors.forename: Dominique
authors.initials: D
authors.lastname: Eeckhout
authors.forename: Fabian
authors.initials: F
authors.lastname: Schweizer
authors.forename: Marta
authors.initials: M
authors.lastname: Godoy
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Franco-Zorrilla
authors.forename: Laurens
authors.initials: L
authors.lastname: Pauwels
authors.forename: Erwin
authors.initials: E
authors.lastname: Witters
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Puga
authors.forename: Javier
authors.initials: J
authors.lastname: Paz-Ares
authors.forename: Alain
authors.initials: A
authors.lastname: Goossens
authors.forename: Philippe
authors.initials: P
authors.lastname: Reymond
authors.forename: Geert
authors.initials: G
authors.lastname: De Jaeger
authors.forename: Roberto
authors.initials: R
authors.lastname: Solano
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism*; D010802:Phylogeny; D018517:Plant Roots / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D013379:Substrate Specificity; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D003517:Cyclopentanes; C473611:MYC2 protein, Arabidopsis; C473612:MYC3 protein, Arabidopsis; C473613:MYC4 protein, Arabidopsis; D054883:Oxylipins; D012097:Repressor Proteins; D015534:Trans-Activators; C011006:jasmonic acid