Assertion: The companion cells help in maintaining the pressue gradient in sieve tube
Reasons: The companion cells are specialished parenchymatous cells which are closely associated with sieve tube elements

Explanation

To analyze the assertion and reason provided in the question, we can break it down into a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "The companion cells help in maintaining the pressure gradient in sieve tubes."
- This means that companion cells play a role in ensuring that there is a difference in pressure within the sieve tubes, which is essential for the transport of nutrients.

2. **Understanding the Reason**:
- The reason given is that "The companion cells are specialized parenchymatous cells which are closely associated with sieve tube elements."
- Companion cells are indeed specialized cells that are closely associated with sieve tube elements in the phloem. They have a vital role in supporting the sieve tubes.

3. **Linking Assertion and Reason**:
- The assertion is supported by the reason because the close association of companion cells with sieve tubes allows them to assist in maintaining the pressure gradient.
- Companion cells have a nucleus, which sieve tube elements lack. This nucleus is crucial for the metabolic functions that help maintain the pressure gradient necessary for the movement of sap through the sieve tubes.

4. **Conclusion**:
- Both the assertion and the reason are correct, and the reason effectively explains why the assertion is true. Therefore, the statement can be concluded as valid.

### Final Answer:
Both the assertion and the reason are correct, and the reason supports the assertion.

---