Question

how the circadian rhythm works at a mechanistic level in plants?

Answer 1

Plant circadian rhythms tell the plant what season it is, and when to flower to attract pollinators for the best chance. Behaviors showing rhythms involve movement of the leaves, development, germination, exchange of stomatal / gas, enzyme activity, photosynthetic activity, and emission of fragrances, among others. Circadian cycles arise when a plant joins to synchronize with the light period of the world around it. These rhythms are generated endogenously and self-supporting, and are relatively constant over a range of ambient temperatures.Essential features involve two active transcription-translation feedback loops: proteins comprising PAS domains that promote interactions between mrna and rna; and many photoreceptors that fine-tune the clock to various light conditions. Anticipating improvements in the climate makes sufficient adjustments in the physiological condition of a plant, which confers an ecological advantage. A greater knowledge of plant circadian rhythms has implications in agriculture, such as having farmers schedule crop harvests to increase the supply of crops and avoiding major weather losses.

Light is the cue that plants synchronize their inner clocks with their environment and are detected by a broad range of photoreceptors. Red and blue light is filtered by multiple phytochromes and cryptochromes. One phytochrome, phyA, is the main phytochrome in seedlings grown in the dark but quickly degraded to produce Cry1 in the light. Phytochromes B – E become more soluble in light-grown seedlings with phyB, the main phytochrome. The cryptochrome (cry) gene is also a light-sensitive feature of the circadian clock and is suspected to be active as a photoreceptor as well as as part of the endogenous pacemaker system of the clock.Cryptochromes 1–2 (involved in blue – UVA) help preserve the duration of the clock's cycle across a variety of light conditions.