Arabidopsis TOE proteins convey a photoperiodic signal to antagonize CONSTANS and regulate flowering time.
Plants flower in an appropriate season to allow sufficient vegetative development and position flower development in favorable environments. In Arabidopsis, CONSTANS (CO) and FLAVIN-BINDING KELCH REPEAT F-BOX1 (FKF1) promote flowering by inducing FLOWER LOCUS T (FT) expression in the long-day afternoon. The CO protein is present in the morning but could not activate FT expression due to unknown negative mechanisms, which prevent premature flowering before the day length reaches a threshold. Here, we report that TARGET OF EAT1 (TOE1) and related proteins interact with the activation domain of CO and CO-like (COL) proteins and inhibit CO activity. TOE1 binds to the FT promoter near the CO-binding site, and reducing TOE function results in a morning peak of the FT mRNA. In addition, TOE1 interacts with the LOV domain of FKF1 and likely interferes with the FKF1-CO interaction, resulting in partial degradation of the CO protein in the afternoon to prevent premature flowering.
State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai 200438, China; Ministry of Education Key Laboratory of Biodiversity and Ecological Engineering, Institute of Biodiversity Sciences, Fudan University, Shanghai 200438, China;
Bailong
B
Zhang
State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai 200438, China;
Liang
L
Wang
State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai 200438, China; Ministry of Education Key Laboratory of Biodiversity and Ecological Engineering, Institute of Biodiversity Sciences, Fudan University, Shanghai 200438, China;
Liping
L
Zeng
State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai 200438, China;
Chao
C
Zhang
State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai 200438, China; Ministry of Education Key Laboratory of Biodiversity and Ecological Engineering, Institute of Biodiversity Sciences, Fudan University, Shanghai 200438, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200438, China hongma@fudan.edu.cn.
Hong
H
Ma
D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D017440:Photoperiod; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*
D029681:Arabidopsis Proteins; C092776:CONSTANS protein, Arabidopsis; D004268:DNA-Binding Proteins; C418905:FT protein, Arabidopsis; D014157:Transcription Factors
CONSTANS; FT expression; TARGET OF EAT; flowering; photoperiod; protein interaction