85. Following are certain statements regarding Gibberellin (GA) signal transduction in Arabidopsis
plants:
A. DELLA is a negative regulator of growth.
B. GA is not required for the interaction of DELLA with GID1 protein.
C. GID is a receptor of GA.
D. DELLA is ubiquitinated only after GDII perceives GA and binds to DELLA.
E. Proteasomal degradation of DELLA is required for the growth of plant.
Which of the following sets of statements is correct?
1. A, B, C and D
2. A, B, C and E
3. A, C, D and E
4. B, D and E

Gibberellin (GA) Signal Transduction Pathway in Arabidopsis

The Gibberellin (GA) signal transduction pathway plays a crucial role in regulating plant growth and development. GA is a plant hormone that controls various biological processes, including seed germination, stem elongation, and flowering. Understanding how GA signaling works is important in the context of plant growth regulation.

Let’s break down the statements about GA signaling in Arabidopsis and identify which set is correct.

Examining the Statements

• A. DELLA is a negative regulator of growth.

  • True: DELLA proteins are known to act as negative regulators of growth. They inhibit plant growth under normal conditions by interacting with other proteins and preventing the expression of genes responsible for growth.

• B. GA is not required for the interaction of DELLA with GID1 protein.

  • False: GA is required for the interaction between DELLA proteins and GID1 (GA Insensitive Dwarf 1). When GA binds to GID1, it causes a conformational change, allowing GID1 to interact with DELLA proteins, leading to their degradation.

• C. GID1 is a receptor of GA.

  • True: GID1 is a receptor for GA. It binds to GA, initiating a signaling cascade that ultimately leads to the degradation of DELLA proteins.

• D. DELLA is ubiquitinated only after GID1 perceives GA and binds to DELLA.

  • True: Ubiquitination of DELLA proteins occurs only after GA is perceived by GID1 and it binds to DELLA. This interaction triggers the degradation of DELLA proteins via the proteasome pathway, enabling plant growth.

• E. Proteasomal degradation of DELLA is required for the growth of plants.

  • True: The proteasomal degradation of DELLA proteins is essential for plant growth. When DELLA proteins are degraded, growth-promoting genes are expressed, leading to various growth processes.

Correct Answer: Option 3

The correct set of statements is Option 3: A, C, D, and E.

Explanation:

• DELLA proteins inhibit plant growth and need to be degraded for growth to occur (A and E).

• GA is required for the interaction between GID1 and DELLA, which triggers the degradation of DELLA proteins (B is false, and D is true).

• GID1 is the receptor for GA and plays a central role in the GA signaling pathway (C is true).

Conclusion

Understanding the GA signal transduction pathway is crucial for regulating plant growth and development. The interaction between DELLA proteins, GID1 receptors, and GA plays a critical role in controlling growth processes in Arabidopsis plants.