title: OsMYC2, an essential factor for JA-inductive sakuranetin production in rice, interacts with MYC2-like proteins that enhance its transactivation ability.
abstract: Biosynthesis of sakuranetin, a flavonoid anti-fungal phytoalexin that occurs in rice, is highly dependent on jasmonic acid (JA) signalling and induced by a variety of environmental stimuli. We previously identified OsNOMT, which encodes naringenin 7-O-methyltransferase (NOMT); NOMT is a key enzyme for sakuranetin production. Although OsNOMT expression is induced by JA treatment, the regulation mechanism that activates the biosynthetic pathway of sakuranetin has not yet been elucidated. In this study, we show that JA-inducible basic helix-loop-helix transcriptional factor OsMYC2 drastically enhances the activity of the OsNOMT promoter and is essential for JA-inducible sakuranetin production. In addition, we identified 2 collaborators of OsMYC2, OsMYC2-like protein 1 and 2 (OsMYL1 and OsMYL2) that further activated the OsNOMT promoter in synergy with OsMYC2. Physical interaction of OsMYC2 with OsMYL1 and OsMYL2 further supported the idea that these interactions lead to the enhancement of the transactivation activity of OsMYC2. Our results indicate that JA signalling via OsMYC2 is reinforced by OsMYL1 and OsMYL2, resulting in the inductive production of sakuranetin during defence responses in rice.
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ogawa
authors.affiliation: Department of Biosciences, Teikyo University, Utsunomiya, Tochigi, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Miyamoto
authors.affiliation: Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Keiichirou
authors.initials: K
authors.lastname: Nemoto
authors.affiliation: Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sawasaki
authors.affiliation: Department of Biosciences, Teikyo University, Utsunomiya, Tochigi, Japan.
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Yamane
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nojiri
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Okada
mesh_terms: D003517:Cyclopentanes / Q000378:metabolism*; D005419:Flavonoids / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant; D008780:Methyltransferases / Q000378:metabolism*; D012275:Oryza / Q000235:genetics*; D054883:Oxylipins / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics; D011401:Promoter Regions, Genetic; D012717:Sesquiterpenes / Q000378:metabolism; D015398:Signal Transduction; D015533:Transcriptional Activation; D059467:Transcriptome; D000094162:Phytoalexins
chemical_list: D003517:Cyclopentanes; D005419:Flavonoids; D054883:Oxylipins; D010940:Plant Proteins; D012717:Sesquiterpenes; C099724:sakuranetin; C011006:jasmonic acid; D008780:Methyltransferases; C099725:naringenin 7-O-methyltransferase; D000094162:Phytoalexins