title: The effects of phytochrome-mediated light signals on the developmental acquisition of photoperiod sensitivity in rice.
abstract: Plants commonly rely on photoperiodism to control flowering time. Rice development before floral initiation is divided into two successive phases: the basic vegetative growth phase (BVP, photoperiod-insensitive phase) and the photoperiod-sensitive phase (PSP). The mechanism responsible for the transition of rice plants into their photoperiod-sensitive state remains elusive. Here, we show that se13, a mutation detected in the extremely early flowering mutant X61 is a nonsense mutant gene of OsHY2, which encodes phytochromobilin (PΦB) synthase, as evidenced by spectrometric and photomorphogenic analyses. We demonstrated that some flowering time and circadian clock genes harbor different expression profiles in BVP as opposed to PSP, and that this phenomenon is chiefly caused by different phytochrome-mediated light signal requirements: in BVP, phytochrome-mediated light signals directly suppress Ehd2, while in PSP, phytochrome-mediated light signals activate Hd1 and Ghd7 expression through the circadian clock genes' expression. These findings indicate that light receptivity through the phytochromes is different between two distinct developmental phases corresponding to the BVP and PSP in the rice flowering process. Our results suggest that these differences might be involved in the acquisition of photoperiod sensitivity in rice.
authors.affiliation: Division of Agronomy and Horticulture Science, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yoshitake
authors.affiliation: Division of Agronomy and Horticulture Science, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Yokoo
authors.affiliation: Division of Agronomy and Horticulture Science, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Saito
authors.affiliation: Division of Agronomy and Horticulture Science, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Takuji
authors.initials: T
authors.lastname: Tsukiyama
authors.affiliation: Division of Agronomy and Horticulture Science, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Xu
authors.initials: X
authors.lastname: Quan
authors.affiliation: Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Zikihara
authors.affiliation: Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Katsura
authors.affiliation: Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Tokutomi
authors.affiliation: Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Aboshi
authors.affiliation: Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Mori
authors.affiliation: Division of Agronomy and Horticulture Science, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Hiromo
authors.initials: H
authors.lastname: Inoue
authors.affiliation: Graduate School of Environmental and Life Science, Okayama University, Okayama 700-8530, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Nishida
authors.affiliation: Graduate School of Biostudies, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kohchi
authors.affiliation: Division of Agronomy and Horticulture Science, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Teraishi
authors.affiliation: Division of Agronomy and Horticulture Science, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Okumoto
authors.affiliation: 1] Division of Agronomy and Horticulture Science, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan [2] Department of Agricultural Regional Vitalization, Kibi International University, Minamiawaji, Hyogo, 656-0484, Japan.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Tanisaka
mesh_terms: D057906:Circadian Clocks / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008027:Light; D009154:Mutation; D012275:Oryza / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D017440:Photoperiod; D010834:Phytochrome / Q000378:metabolism*; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000378:metabolism; D015398:Signal Transduction / Q000528:radiation effects*
chemical_list: D010940:Plant Proteins; D012330:RNA, Double-Stranded; D010834:Phytochrome; D010088:Oxidoreductases; C071703:phytochromobilin synthase