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The circadian clock in plants has completely different components to those in the animal, fungus, or bacterial clocks. The plant clock does have a conceptual similarity to the animal clock in that it consists of a series of interlocking transcriptional feedback loops. The genes involved in the clock show their peak expression at a fixed time of ...
CCA1 – The CCA1 gene, also known as Circadian and Clock Associated Gene 1, is a gene that is especially important in maintaining the rhythmicity of plant cellular oscillations. Overexpression, results in the loss of rhythmic expression of clock controlled genes (CCGs), loss of photoperiod control, and loss of rhythmicity in LHY expression.
CAB is confined to the mesophyll and guard cells and the cycling of CAB expression in the Arabidopsis plant suggests that there is a circadian clock that controls the CAB gene. [16] [17] When the plants were moved from light/dark cycles to constant darkness, CAB2 and CAB3 genes showed an exaggerated circadian cycling. [17]
A better understanding of plant circadian rhythms has applications in agriculture, such as helping farmers stagger crop harvests to extend crop availability and securing against massive losses due to weather. Light is the signal by which plants synchronize their internal clocks to their environment and is sensed by a wide variety of photoreceptors.
The conception of the plant biological clock as made up of interacting negative feedback loops is unique in comparison to mammal and fungal circadian clocks which contain autoregulatory negative feedback loops with positive and negative elements [6] (see "Transcriptional and non-transcriptional control on the Circadian clock page).
A circadian cycle was first observed in the 18th century in the movement of plant leaves by the French scientist Jean-Jacques d'Ortous de Mairan. [ 5 ] [ 6 ] In 1751 Swedish botanist and naturalist Carl Linnaeus (Carl von Linné) designed a flower clock using certain species of flowering plants .
The gene codes for a transcriptional repressor, TOC1, one of five pseudo-response regulators (PRR) that mediate the period of the circadian clock in plants. The TOC1 protein is involved in the clock's evening loop, which is a repressilator that directly inhibits transcription of morning loop genes LHY and CCA1. [1]
Circadian Clock Associated 1 (CCA1) is a gene that is central to the circadian oscillator of angiosperms. It was first identified in Arabidopsis thaliana in 1993. CCA1 interacts with LHY and TOC1 to form the core of the oscillator system.