Fig. 4.

Late night/dawn inductions of CONSTANS (CO) and FLOWERING LOCUS T (FT) transcript accumulation are conserved over 2 wk, dusk suppression declines as plants age in Arabidopsis thaliana (Columbia-0 (Col-0)). (a) CO and (b) FT transcript accumulation in LD22/22°C (long days with day: night temperatures = 22°C: 22°C) and LD22/12°C conditions for two consecutive weeks. Narrow, horizontal black bar designates day 4 of treatment. Seedlings were harvested at zeitgeber time (ZT, hours after dawn) 0, ZT8, and ZT16. Seedlings were grown for 7 d in short days (SD) before being transferred to LD, temperature treatments; harvest began on day 1 in treatments. Data represent means ± SEM derived from five biological replicates. (c, d) FT transcript accumulation on day 4 of LD, temperature treatments in 18-d-old seedlings (c), and in 25-d-old (d) seedlings harvested at the same time. Seedlings were kept in short days until moved to the treatments. Data represent means ± SEM derived from at least three biological replicates. (a–d) Asterisks (*) indicate P<0.05 and 95% CI of difference between pair did not contain zero.