EARLY FLOWERING 3 controls temperature responsiveness of the circadian clock

Abstract

Predictable changes in light and temperature during a diurnal cycle are major entrainment cues that enable the circadian clock to generate internal biological rhythms that are synchronized with the external environment. With the average global temperature predicted to keep increasing, the intricate light-temperature coordination that is necessary for clock functionality is expected to be seriously affected. Hence, understanding how temperature signals are perceived by the circadian clock has become an important issue, especially in light of climate change scenarios. In Arabidopsis, the clock component EARLY FLOWERING 3 (ELF3) not only serves as an essential light Zeitnehmer, but also functions as a thermosensor participating in thermomorphogenesis. However, the role of ELF3 in temperature entrainment of the circadian clock is not fully understood. Here, we report that ELF3 is essential for delivering temperature input to the clock. We demonstrate that in the absence of ELF3, the oscillator was unable to properly respond to temperature changes, resulting in an impaired gating of thermoresponses. Consequently, clock-controlled physiological processes such as rhythmic growth and cotyledon movement were disturbed. Together, our results reveal that ELF3 is an essential Zeitnehmer for temperature sensing of the oscillator, and thereby for coordinating the rhythmic control of thermoresponsive physiological outputs.