Insight into a Physiological Role for the EC Night-Time Repressor in the Arabidopsis Circadian Clock

Life cycle adaptation to seasonal variation in photoperiod and temperature is a major determinant of ecological success of widespread domestication of Arabidopsis thaliana. The circadian clock plays a role in the underlying mechanism for adaptation. Nevertheless, the mechanism by which the circadian clock tracks seasonal changes in photoperiod and temperature is a longstanding subject of research in the field. We previously showed that a set of the target genes (i.e. GI, LNK1. PRR9 and PRR7) of the Evening Complex (EC) consisting of LUX–ELF3–ELF4 is synergistically induced in response to both warm-night and night-light signals. Here, we further show that the responses occur within a wide range of growth-compatible temperatures (16–28°C) in response to a small change in temperature (4°C). A dim light pulse (<1 µmol m–2 s–1) causes the enhanced effect on the transcription of EC targets. The night-light pulse antagonizes against a positive effect of the cool-night signal on the EC activity. The mechanism of double-checking external temperature and light signals through the EC nighttime repressor might enable plants to ignore (or tolerate) daily fluctuation of ambient temperature within a short time interval in their natural habitats. Taken together, the EC night-time repressor might play a physiological role in tracking seasonal variation in photoperiod and temperature by conservatively double-checking both the light and temperature...
Source: Plant and Cell Physiology - Category: Cytology Authors: Tags: Regular Papers Source Type: research