circadian-clock
The circadian clock is an internal biochemical timekeeping system that allows organisms to anticipate and synchronize their biological processes with the roughly 24-hour cycle of day and night. In plants, this molecular clock coordinates critical functions such as photosynthesis, growth, flowering time, and stress responses, enabling them to optimally allocate energy and resources according to predictable environmental rhythms. Understanding these regulatory mechanisms offers insights into how plants adapt to seasonal changes and environmental stressors, with potential applications in improving crop yield and resilience.
open_in_new WikipediaPubMed · 2026-06-18
Researchers found that a single tiny genetic change in a key plant clock gene (ELF3) shifts how long Arabidopsis's internal daily rhythm runs, and that plants carrying this variant have thrived in hot, seasonally extreme climates — likely spreading as the last ice age receded from Europe.
A single non-coding DNA change in intron 2 of the ELF3 clock gene alters expression of a shorter protein variant (ELF3β), shifting the plant's circadian period length and enabling adaptation to continental climates with high seasonal temperature variability.
Circadian rhythms measured across 287 global Arabidopsis accessions via genome-wide association study identified multiple ELF3 variants defining three distinct haplogroups, each linked to different patterns of seasonal temperature.
Statistical signatures of a selective sweep in continental-climate haplogroups indicate this adaptation likely spread during Europe's most recent de-glaciation, demonstrating that natural selection has actively targeted a core circadian clock gene in response to climate.
