Plant photomorphogenetic reactions are media ted by a pigment

Options

A. Phytochrome
B. Anthocyanin
C. Cytochrome
D. All the above

Answer

To solve the question "Plant photomorphogenetic reactions are mediated by a pigment," we will follow these steps:

### Step-by-Step Solution:

1. **Understand Photomorphogenesis**:
- Photomorphogenesis refers to the growth and development of plants in response to light signals. It is crucial for various developmental processes, including seed germination, leaf expansion, and flowering.

2. **Identify the Role of Pigments**:
- In plants, certain pigments act as photoreceptors that detect light and mediate photomorphogenetic responses. These pigments play a significant role in how plants respond to different light conditions.

3. **Evaluate the Options**:
- The options provided are:
- A) Phytochrome
- B) Anthocyanin
- C) Cytochrome
- D) All of the above
- We need to determine which of these pigments is primarily responsible for mediating photomorphogenetic reactions.

4. **Focus on Phytochrome**:
- Phytochromes are a specific group of photoreceptors that are particularly known for their role in photomorphogenesis. They respond to red and far-red light and are crucial for processes like seed germination and seedling elongation.

5. **Consider Other Options**:
- Anthocyanins are pigments that provide color to flowers and fruits but are not primarily involved in photomorphogenetic responses.
- Cytochromes are involved in cellular respiration and photosynthesis but do not mediate photomorphogenetic reactions.

6. **Conclusion**:
- Based on the information, the correct answer is **A) Phytochrome**. Phytochromes are the primary pigments that mediate photomorphogenetic reactions in plants.

### Final Answer:
**A) Phytochrome**