ABA acts antagonistic to

Options

A. Ethylene
B. Cytokinin
C. Gibberlic acid
D. IAA

Answer

**Step-by-Step Solution:**

1. **Understanding ABA (Abscisic Acid)**:
- Abscisic acid (ABA) is a plant hormone often referred to as the "stress hormone." It plays a crucial role in plant responses to stress conditions, such as drought or salinity.

2. **Defining Antagonistic Action**:
- The term "antagonistic" refers to the action of one substance opposing or counteracting the effects of another. In this context, we need to identify which plant hormone ABA acts antagonistically against.

3. **Identifying Other Plant Hormones**:
- The question presents several plant hormones: ethylene, cytokinin, gibberellic acid (GA), and IAA (Indole-3-acetic acid, an auxin). We need to analyze their functions to determine which one ABA opposes.

4. **Analyzing Gibberellic Acid**:
- Gibberellic acid is known for promoting growth and development in plants. It encourages seed germination, stem elongation, and the breaking of dormancy.

5. **Contrasting ABA and Gibberellic Acid**:
- ABA has the opposite effect of gibberellic acid:
- **Growth Inhibition**: ABA inhibits growth, while gibberellic acid promotes it.
- **Dormancy Promotion**: ABA promotes seed dormancy, whereas gibberellic acid helps overcome dormancy.
- **Protein Synthesis**: ABA inhibits mRNA and protein synthesis, while gibberellic acid promotes it.
- **Leaf Senescence**: ABA promotes leaf senescence (aging and shedding), while gibberellic acid prevents leaf shedding.

6. **Conclusion**:
- Based on the analysis, ABA acts antagonistically to gibberellic acid (GA).

**Final Answer**: ABA acts antagonistically to gibberellic acid (GA).

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