Arabidopsis TOE proteins convey a photoperiodic signal to antagonize CONSTANS and regulate flowering time.

Bailong Zhang, Liang Wang, Liping Zeng, Chao Zhang, Hong Ma

Genes & development 2015 May 1

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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. © 2015 Zhang et al.; Published by Cold Spring Harbor Laboratory Press.

Citation

Bailong Zhang, Liang Wang, Liping Zeng, Chao Zhang, Hong Ma. Arabidopsis TOE proteins convey a photoperiodic signal to antagonize CONSTANS and regulate flowering time. Genes & development. 2015 May 1;29(9):975-87