LOV KELCH PROTEIN2 and ZEITLUPE repress Arabidopsis photoperiodic flowering under non-inductive conditions, dependent on FLAVIN-BINDING KELCH REPEAT F-BOX1

• Published in: The Plant journal : for cell and molecular biology Vol. 67; no. 4; pp. 608 - 621
• Main Authors: Takase, Tomoyuki, Nishiyama, Yuuki, Tanihigashi, Haruna, Ogura, Yasunobu, Miyazaki, Yuji, Yamada, Yumiko, Kiyosue, Tomohiro
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.08.2011; Blackwell
• Subjects: Arabidopsis; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - physiology; Arabidopsis - ultrastructure; Arabidopsis Proteins; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biological and medical sciences; Biology and morphogenesis of the reproductive apparatus. Photoperiodism, vernalisation; Cell Nucleus; Cell Nucleus - metabolism; circadian rhythm; Cytosol; Cytosol - metabolism; Down-Regulation; F-box proteins; F-Box Proteins - genetics; F-Box Proteins - metabolism; FLAVIN‐BINDING KELCH REPEAT F‐BOX1 (FKF1); flowering; flowering time; Flowers; Flowers - genetics; Flowers - physiology; Fundamental and applied biological sciences. Psychology; Gene expression; gene expression regulation; Gene Expression Regulation, Plant; Gene Expression Regulation, Plant - physiology; gene overexpression; Genetic Complementation Test; genetics; growth & development; LOV KELCH PROTEIN2 (LKP2); metabolism; Phenotype; Photoperiod; photoperiodic pathway; photophase; physiology; Plant biology; Plant growth; Plant Leaves; Plant Leaves - genetics; Plant Leaves - physiology; Plant physiology and development; Plant Shoots; Plant Shoots - genetics; Plant Shoots - physiology; Plants, Genetically Modified; Plants, Genetically Modified - genetics; Plants, Genetically Modified - growth & development; Plants, Genetically Modified - physiology; Plants, Genetically Modified - ultrastructure; Proteins; Sequence Deletion; Translocation; ultrastructure; Vegetative and sexual reproduction, floral biology, fructification; ZEITLUPE (ZTL); Binding; Arabidopsis; Repression; photoperiodic pathway; Floral transition; Arabidopsis thaliana; ZEITLUPE (ZTL); Cruciferae; Dicotyledones; Angiospermae; Flowering; FLAVIN-BINDING KELCH REPEAT F-BOX1 (FKF1); Spermatophyta; LOV KELCH PROTEIN2 (LKP2); Flowering time
• ISSN: 0960-7412; 1365-313X; 1365-313X
• DOI: 10.1111/j.1365-313x.2011.04618.x

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.