bHLH003, bHLH013 and bHLH017 are new targets of JAZ repressors negatively regulating JA responses.
Cell reprogramming in response to jasmonates requires a tight control of transcription that is achieved by the activity of JA-related transcription factors (TFs). Among them, MYC2, MYC3 and MYC4 have been described as activators of JA responses. Here we characterized the function of bHLH003, bHLH013 and bHLH017 that conform a phylogenetic clade closely related to MYC2, MYC3 and MYC4. We found that these bHLHs form homo- and heterodimers and also interact with JAZ repressors in vitro and in vivo. Phenotypic analysis of JA-regulated processes, including root and rosette growth, anthocyanin accumulation, chlorophyll loss and resistance to Pseudomonas syringae, on mutants and overexpression lines, suggested that these bHLHs are repressors of JA responses. bHLH003, bHLH013 and bHLH017 are mainly nuclear proteins and bind DNA with similar specificity to that of MYC2, MYC3 and MYC4, but lack a conserved activation domain, suggesting that repression is achieved by competition for the same cis-regulatory elements. Moreover, expression of bHLH017 is induced by JA and depends on MYC2, suggesting a negative feed-back regulation of the activity of positive JA-related TFs. Our results suggest that the competition between positive and negative TFs determines the output of JA-dependent transcriptional activation.
Departamento de Genetica Molecular de Plantas, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, Madrid, Spain.
Sandra
S
Fonseca
Departamento de Genetica Molecular de Plantas, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, Madrid, Spain.
Patricia
P
Fernández-Calvo
Departamento de Genetica Molecular de Plantas, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, Madrid, Spain.
Guillermo M
GM
Fernández
Departamento de Genetica Molecular de Plantas, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, Madrid, Spain.
Monica
M
Díez-Díaz
Departamento de Genetica Molecular de Plantas, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, Madrid, Spain.
Selena
S
Gimenez-Ibanez
Genomics Unit, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, Madrid, Spain.
Irene
I
López-Vidriero
Genomics Unit, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, Madrid, Spain.
Marta
M
Godoy
Departamento de Genetica Molecular de Plantas, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, Madrid, Spain.
Gemma
G
Fernández-Barbero
Department of Plant Systems Biology, VIB, Gent, Belgium ; Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium.
Jelle
J
Van Leene
Department of Plant Systems Biology, VIB, Gent, Belgium ; Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium.
Geert
G
De Jaeger
Genomics Unit, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, Madrid, Spain.
José Manuel
JM
Franco-Zorrilla
Departamento de Genetica Molecular de Plantas, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, Madrid, Spain.
Roberto
R
Solano
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000502:physiology*; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000502:physiology*; D016384:Consensus Sequence; D003517:Cyclopentanes / Q000378:metabolism*; D018744:DNA, Plant; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D009928:Organ Specificity; D054883:Oxylipins / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism; D011485:Protein Binding; D055503:Protein Multimerization; D012097:Repressor Proteins / Q000502:physiology*
D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D003517:Cyclopentanes; D018744:DNA, Plant; D054883:Oxylipins; D010937:Plant Growth Regulators; D012097:Repressor Proteins; C011006:jasmonic acid