title: Basic helix-loop-helix transcription factors JASMONATE-ASSOCIATED MYC2-LIKE1 (JAM1), JAM2, and JAM3 are negative regulators of jasmonate responses in Arabidopsis.
abstract: Jasmonates regulate transcriptional reprogramming during growth, development, and defense responses. Jasmonoyl-isoleucine, an amino acid conjugate of jasmonic acid (JA), is perceived by the protein complex composed of the F-box protein CORONATINE INSENSITIVE1 (COI1) and JASMONATE ZIM DOMAIN (JAZ) proteins, leading to the ubiquitin-dependent degradation of JAZ proteins. This activates basic helix-loop-helix-type MYC transcription factors to regulate JA-responsive genes. Here, we show that the expression of genes encoding other basic helix-loop-helix transcription factors, JASMONATE ASSOCIATED MYC2-LIKE1 (JAM1), JAM2, and JAM3, is positively regulated in a COI1- and MYC2-dependent manner in Arabidopsis (Arabidopsis thaliana). However, contrary to myc2, the jam1jam2jam3 triple mutant exhibited shorter roots when treated with methyl jasmonate (MJ), indicating enhanced responsiveness to JA. Our genome-wide expression analyses revealed that key jasmonate metabolic genes as well as a set of genes encoding transcription factors that regulate the JA-responsive metabolic genes are negatively regulated by JAMs after MJ treatment. Consistently, loss of JAM genes resulted in higher accumulation of anthocyanin in MJ-treated plants as well as higher accumulation of JA and 12-hydroxyjasmonic acid in wounded plants. These results show that JAMs negatively regulate the JA responses in a manner that is mostly antagonistic to MYC2.
authors.affiliation: RIKEN Plant Science Center, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Sasaki-Sekimoto
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Jikumaru
authors.forename: Takeshi
authors.initials: T
authors.lastname: Obayashi
authors.forename: Hikaru
authors.initials: H
authors.lastname: Saito
authors.forename: Shinji
authors.initials: S
authors.lastname: Masuda
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamiya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohta
authors.forename: Ken
authors.initials: K
authors.lastname: Shirasu
mesh_terms: D000872:Anthocyanins / Q000096:biosynthesis; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D053898:Biosynthetic Pathways / Q000235:genetics; D003517:Cyclopentanes / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D054883:Oxylipins / Q000494:pharmacology*; D010802:Phylogeny; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000502:physiology
chemical_list: D000872:Anthocyanins; D029681:Arabidopsis Proteins; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D003517:Cyclopentanes; D054883:Oxylipins; C525743:AIB protein, Arabidopsis; C587484:JAM2 protein, Arabidopsis; C587485:JAM3 protein, Arabidopsis; C473611:MYC2 protein, Arabidopsis; C011006:jasmonic acid