Etiolation in Action
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- Duration: 3:08
- Published: 2009-03-07
- Uploaded: 2010-09-22
- Author: jtcarr4
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Chloroplasts that have not been exposed to light are called etioplasts (see also plastids).
De-etiolation, on the other hand, 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 of photosynthesis now that it is in sunlight.
Some of the changes that occur include: #Inhibition of hypocotyl lengthening. #Stimulation of cotyledon expansion. #Opening of the apical hook. #Stimulation of synthesis of anthocyanins. #Stimulation of chloroplasts development from etioplasts.
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.
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