Photomorphogenesis

Definition

Photomorphogenesis is the process by which plants develop and grow in response to light signals. This phenomenon regulates various aspects of plant physiology, including seed germination, stem elongation, and leaf expansion.

5 Must Know Facts For Your Next Test

1. Photomorphogenesis is primarily mediated by photoreceptors such as phytochromes, cryptochromes, and phototropins.
2. Red and blue light are the most influential wavelengths in triggering photomorphogenic responses.
3. Phytochrome exists in two forms, Pr and Pfr, that interconvert based on red or far-red light exposure.
4. The process helps seedlings switch from skotomorphogenesis (growth in darkness) to photomorphogenesis upon exposure to light.
5. Photomorphogenesis plays a critical role in optimizing photosynthesis by regulating chlorophyll production and leaf orientation.

Review Questions

• What are the main types of photoreceptors involved in photomorphogenesis?
• How do red and blue light influence plant development differently?
• Explain the significance of phytochrome conversion between Pr and Pfr forms.

Related terms

Phototropism: Directional growth of a plant toward or away from a light source.

Phytochrome: A type of photoreceptor that detects red and far-red light, crucial for regulating photomorphogenic processes.

Cryptochrome: A class of flavoproteins that are sensitive to blue light and play roles in circadian rhythms and development.