Showing the difference between etiolation and de–etiolation Spanish Bluebells Hyacinthoides hispanica, showing both leaves and flowers in both etiolated and non–etiolated states. De–etiolation, is a series of physiological and biochemical changes a plant shoot undergoes in response to sunlight.
This process is also known informally as greening. The changes triggered in the plant shoot all occur in preparation for photosynthesis.
This process is regulated by the exposure of various photoreceptor pigments to light. Phytochrome A and phytochrome B both respond to an increasing proportion of red light to far–red light which occurs when the shoot comes out into the open. Cryptochrome 1 responds to increasing amounts of blue light when the shoot reaches the surface.
Importance of De–etiolation Phenomenon : When a shoot reaches the sunlight, the plant undergoes profound changes collectively called de–etiolation (informally known as greening). The elongation rate of the stems slows; leaves expand; roots elongate; and the shoot produces chlorophyll. In short, it begins to resemble a typical plant.