光敏色素
早晨
黄昏
生物
拟南芥
远红色
基因座(遗传学)
植物
基因表达
昼夜节律
光周期性
遗传学
避光
基因
生物物理学
红灯
生态学
内分泌学
突变体
作者
Nayoung Lee,Yusuke Ozaki,Andrew K. Hempton,Hiroshi Takagi,Savita Purusuwashi,Young Hun Song,Motomu Endo,Atsuhito Kubota,Takato Imaizumi
摘要
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.
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