Plant Circadian Rhythms

• Circadian clocks are found in most eukaryotic organisms. By allowing anticipation of daily and seasonal changes, they enable coordination of metabolism and lifecycle with the natural rhythms of the environment. Plant circadian rhythms are generated by a series of interlocking feedback loops of RNA (ribonucleic acid) and protein expression that respond to environmental cycles of light and temperature. They control essential processes in the plant's development, such as the transition to flowering or growth cessation, and thus influence yield, plant growth and biomass production. Many components of the clock are conserved across a wide variety of plant species and thus research in Arabidopsis translates into an understanding of the clock in agricultural crops or long‐living deciduous tree species such as hybrid aspen.Key ConceptsCircadian clocks are found in both eukaryotes and bacteria.Circadian clocks have a free‐running periodicity of about 24 h but are normally entrained to environmental cycles of light and temperature.Temperature compensation is a key feature of the circadian clock and thus the free‐running period length varies relatively little across the range of ambient temperature.The clock underlies many aspects of plant metabolism and physiology because it can detect and respond to both short‐term (the day:night cycle) and long‐term (the pattern of daylength variation across a year) changes in light and temperature.The circadian clock of plants is made up of a series of interconnected transcription‐translation feedback loops (TTFLs) governing cycles of mRNA and protein expression.Every plant cell contains its own clock. Clocks in different cells may be entrained independently of one another, although there appears to be a hierarchy of clocks within a plant dominated by the apex.Plants with malfunctioning clocks suffer reductions in growth.Many of the key components of the plant clock first described in the model species Arabidopsis thaliana are conserved across a wide range of species including trees such as hybrid aspen.

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NATURVETENSKAP  -- Biologi -- Botanik (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Botany (hsv//eng)

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