title: Blue light-promoted rice leaf bending and unrolling are due to up-regulated brassinosteroid biosynthesis genes accompanied by accumulation of castasterone.
abstract: In this study the relationship between blue light- and brassinosteroid-enhanced leaf lamina bending and unrolling in rice was investigated. Twenty-four hours (h) irradiation with white or blue light increased endogenous brassinosteroid levels, especially those of typhasterol and castasterone, in aerial tissues of rice seedlings. There was an accompanying up-regulation of transcript levels of CYP85A1/OsDWARF, encoding an enzyme catalyzing C-6 oxidation, after 6h under either white or blue light. These effects were not observed in seedlings placed under far-red or red light regimes. It was concluded that blue light up-regulates the levels of several cytochrome P450 enzymes including CYP85A1, thereby promoting the synthesis of castasterone, a biologically active brassinosteroid in rice. Based on these findings, it is considered that blue light-mediated rice leaf bending and unrolling are consequences of the enhanced biosynthesis of endogenous castasterone. In contrast to aerial tissues, brassinosteroid synthesis in roots appeared to be negatively regulated by white, blue and red light but positively controlled by far-red light.
authors.affiliation: Department of Biosciences, Teikyo University, 1-1 Toyosatodai, Utsunomiya, Tochigi 320-8551, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Asahina
authors.affiliation: Department of Biosciences, Teikyo University, 1-1 Toyosatodai, Utsunomiya, Tochigi 320-8551, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tamaki
authors.affiliation: Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Department of Biosciences, Teikyo University, 1-1 Toyosatodai, Utsunomiya, Tochigi 320-8551, Japan.
authors.forename: Kyomi
authors.initials: K
authors.lastname: Shibata
authors.affiliation: Department of Biosciences, Teikyo University, 1-1 Toyosatodai, Utsunomiya, Tochigi 320-8551, Japan.
authors.forename: Takahito
authors.initials: T
authors.lastname: Nomura
authors.affiliation: Department of Biosciences, Teikyo University, 1-1 Toyosatodai, Utsunomiya, Tochigi 320-8551, Japan. Electronic address: yokota@nasu.bio.teikyo-u.ac.jp.
authors.forename: Takao
authors.initials: T
authors.lastname: Yokota
mesh_terms: D060406:Brassinosteroids / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects; D002777:Cholestanols / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects*; D017930:Genes, Reporter; D008027:Light; D009928:Organ Specificity; D012275:Oryza / Q000235:genetics / Q000502:physiology / Q000528:radiation effects*; D010641:Phenotype; D052585:Phloem / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D018517:Plant Roots / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D036226:Seedlings / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors; D015854:Up-Regulation
chemical_list: D060406:Brassinosteroids; D002777:Cholestanols; D010940:Plant Proteins; C083545:castasterone; D003577:Cytochrome P-450 Enzyme System
keywords: Blue light; Brassinosteroid biosynthesis; Cytochrome P450; Oryza sativa; Poaceae; Rice lamina bending and unrolling