title: LOV KELCH PROTEIN2 and ZEITLUPE repress Arabidopsis photoperiodic flowering under non-inductive conditions, dependent on FLAVIN-BINDING KELCH REPEAT F-BOX1.
abstract: LOV KELCH PROTEIN2 (LKP2), ZEITLUPE (ZTL)/LOV KELCH PROTEIN1 (LKP1) and FLAVIN-BINDING KELCH REPEAT F-BOX1 (FKF1) constitute a family of Arabidopsis F-box proteins that regulate the circadian clock. Over-expression of LKP2 or ZTL causes arrhythmicity of multiple clock outputs under constant light and in constant darkness. Here, we show the significance of LKP2 and ZTL in the photoperiodic control of flowering time in Arabidopsis. In plants over-expressing LKP2, CO and FT expression was down-regulated under long-day conditions. LKP2 and ZTL physically interacted with FKF1, which was recruited from the nucleus into cytosolic speckles. LKP2 and ZTL inhibited the interaction of FKF1 with CYCLING DOF FACTOR 1, a ubiquitination substrate for FKF1 that is localized in the nucleus. The Kelch repeat regions of LKP2 and ZTL were sufficient for their physical interaction with FKF1 and translocation of FKF1 to the cytoplasm. Over-expression of LKP2 Kelch repeats induced late flowering under long-day conditions. lkp2 ztl double mutant plants flowered earlier than wild-type plants under short-day (non-inductive) conditions, and both CO and FT expression levels were up-regulated in the double mutant plants. The early flowering of lkp2 ztl was dependent on FKF1. LKP2, ZTL or both affected the accumulation of FKF1 protein during the early light period. These results indicate that an important role of LKP2 and ZTL in the photoperiodic pathway is repression of flowering under non-inductive conditions, and this is dependent on FKF1.
authors.affiliation: Department of Life Science, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Takase
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Nishiyama
authors.forename: Haruna
authors.initials: H
authors.lastname: Tanihigashi
authors.forename: Yasunobu
authors.initials: Y
authors.lastname: Ogura
authors.forename: Yuji
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Yamada
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kiyosue
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D015536:Down-Regulation; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D005816:Genetic Complementation Test; D010641:Phenotype; D017440:Photoperiod; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology; D018520:Plant Shoots / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000502:physiology / Q000648:ultrastructure; D017384:Sequence Deletion
chemical_list: D029681:Arabidopsis Proteins; D044783:F-Box Proteins; C410504:FKF1 protein, Arabidopsis; C450148:LKP2 protein, Arabidopsis; C410503:ZTL protein, Arabidopsis