A pigment due to which root nodules of leguminous plants are pinkish, is

Options

A. phycoerythrin
B. bacteriochlorophyll
C. bacterioviridin
D. leghaemoglobin

Answer

**Step-by-Step Solution:**

1. **Identify the Context**: The question asks about a pigment that gives root nodules of leguminous plants their pinkish color. We need to understand the role of these nodules and the associated bacteria.

2. **Understand Leguminous Plants**: Leguminous plants, such as peas and beans, form root nodules that are crucial for nitrogen fixation. These nodules are formed in association with specific bacteria.

3. **Recognize the Role of Bacteria**: The bacteria present in the root nodules are primarily from the genus Rhizobium. These bacteria are responsible for converting atmospheric nitrogen into ammonia, a form that plants can use.

4. **Identify the Pigment**: The pinkish color of the root nodules is due to a specific pigment produced by the bacteria. This pigment is known as leghemoglobin.

5. **Function of Leghemoglobin**: Leghemoglobin serves an important function as an oxygen scavenger. It binds to oxygen, thereby protecting the nitrogenase enzyme present in the nodules from oxygen, which would otherwise inhibit the nitrogen fixation process.

6. **Conclusion**: The pigment responsible for the pinkish color of root nodules in leguminous plants is leghemoglobin.

**Final Answer**: The pigment due to which root nodules of leguminous plants are pinkish is leghemoglobin.

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