The problem
Imagine following a plant’s daily rhythm in a cool room and a warm room, with no repeating sunrise to reset it. Its internal clock can keep roughly the same pace even though many chemical reactions change speed with temperature. How do the clock’s parts combine to keep that pace stable within temperatures the plant can tolerate?[1] [2]
The small plant Arabidopsis retains a relatively stable daily clock period across tolerable temperatures despite temperature-sensitive chemistry. How do its interacting components achieve this? Clock proteins help control when other clock genes are active, forming feedback loops. In a 2024 study, two proteins that normally lengthen the period, PRR5 and TOC1, were reduced at low temperature through a removal pathway involving LKP2. Plants lacking LKP2 retained more of these proteins and had longer periods in the cold. This gives a concrete compensating contribution, rather than a complete explanation of the network.[1] [2]
Scope
The interacting molecular mechanisms that stabilize the Arabidopsis circadian period across a physiological temperature range.
What remains open
The 2025 review leaves open how LKP2 recognizes its targets preferentially in the cold and how protein removal combines with other temperature-dependent regulation. Changes in a clock protein’s amount need not all contribute to compensation. Temperature compensation also remains distinct from entrainment, the synchronization of internal time to external cycles.[1] [2]
Why it matters
Experiments linking clock–day matching to carbon uptake and growth establish a consequence of accurate timing; they do not isolate temperature compensation as the cause of those benefits. The mechanistic question is how feedback produces a stable collective pace from responsive parts, a design problem shared by other biological networks.[1] [3]
Definitions
2 terms
circadian period
The time needed for one cycle of an internal daily rhythm, measured without a repeating external cue setting each cycle.[1]
entrainment
Synchronization of an internal rhythm to repeating environmental cues, such as a light–dark cycle. This differs from keeping its period relatively stable at different constant temperatures.[1]
Sources
- Temperature compensation of the Arabidopsis circadian clock
Notes on Temperature compensation of the Arabidopsis circadian clock
Review distinguishes a clock’s pace at different constant temperatures from its synchronization to external cycles. It describes cold-dependent protein removal and the open question of how temperature-sensitive components combine in the network.
- Cold-induced degradation of core clock proteins implements temperature compensation in the circadian clock
Notes on Cold-induced degradation of core clock proteins implements temperature compensation in the circadian clock
Arabidopsis experiments identify cold-induced removal of PRR5 and TOC1 through a pathway involving LKP2. Mutant and clock-period results support one compensating contribution under tested conditions, rather than a complete explanation of all temperature responses.
- Plant circadian clocks increase photosynthesis, growth, survival, and competitive advantage
Notes on Plant circadian clocks increase photosynthesis, growth, survival, and competitive advantage
Primary Arabidopsis study connects matching the internal clock period to the external light–dark cycle with more carbon fixation and growth. It does not isolate temperature compensation as the cause. Published in the July 22, 2005 Science issue; a separate first-online day was not verified.