Figure 4.

Pn FT1 and Pn FT2 Transcript Rhythms Are Set by Light off in Pharbitis cv Violet.

(A) to (E) DNA gel blots of RT-PCR products detecting expression of Pn FT1 (A), Pn FT2 (B), Pn CAB (C), Pn CO (D), and ubq (E). Plants were grown under 14 h light/10 h dark and at dawn (Time 0) on the fifth day were divided into five populations, which were exposed to light for different lengths of time and then transferred to darkness. Cotyledons were harvested from the five populations every 4 h.

(F) A diagram illustrating the phase relationship between Pn FT1, Pn FT2, Pn CO, and Pn CAB in darkness. The peak times of expression of the genes relative to dawn is plotted. The horizontal axis represents time after dawn on the fifth day (see legend to [A] to [E]). The vertical axis represents the time after dawn at which each population was transferred to darkness and this time is indicated (e.g., DD10 spent 10 h in light before transfer to darkness). The results for the first four populations of plants shifted to darkness after 10, 16, 22, and 28 h are plotted, and the time that each population was transferred to darkness is illustrated in the diagram by the transition from light to shade. Error bars show se of three PCR experiments. A biological replicate provided a similar result.