1. The FLOWERING LOCUS T gene expression is controlled by high‐irradiance response and external coincidence mechanism in long days in Arabidopsis.
- Author
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Lee, Nayoung, Ozaki, Yusuke, Hempton, Andrew K., Takagi, Hiroshi, Purusuwashi, Savita, Song, Young Hun, Endo, Motomu, Kubota, Akane, and Imaizumi, Takato
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GENE expression , *COINCIDENCE , *ARABIDOPSIS , *CIRCADIAN rhythms , *LOCUS (Genetics) , *PHYTOCHROMES - Abstract
Summary: In natural long days, the florigen gene FLOWERING LOCUS T (FT) shows a bimodal expression pattern with morning and dusk peaks in Arabidopsis. This pattern differs from the one observed in the laboratory, and little is known about underlying mechanisms. A red : far‐red (R : FR) ratio difference between sunlight and fluorescent light causes this FT pattern mismatch.We showed that bimodal FT expression patterns were induced in a day longer than 14 h with sunlight R : FR (= c. 1) conditions. By circadian gating experiments, we found that cumulative exposure of R : FR‐adjusted light (R : FR ratio was adjusted to 1 with FR supplement) spanning from the afternoon to the next morning required full induction of FT in the morning. Conversely, only 2 h of R : FR adjustment in the late afternoon was sufficient for FT induction at dusk.We identified that phytochrome A (phyA) is required for the morning FT expression in response to the R : FR adjustment on the previous day. As a part of this mechanism, we showed that PHYTOCHROME‐INTERACTING FACTOR 7 contributes to FT regulation.Our results suggest that phyA‐mediated high‐irradiance response and the external coincidence mechanism contribute to morning FT induction under natural long‐day conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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