73. Following are certain statements regarding FLOWERING LOCUS C (FLC) gene in Arabidopsis:
A. FLC is a strong repressor of flowering.
B. Higher expression of FLC induces early flowering.
C. FLC is activated by FRIGIDA (FRI).
D. Vernalisation represses FLC.
Which of the following sets of statements is correct?
1. A, B and C
2. A, B and D
3. B, C and D
4. A. C and D

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Introduction to FLOWERING LOCUS C (FLC) Gene in Arabidopsis

The FLOWERING LOCUS C (FLC) gene is a key regulator of flowering time in Arabidopsis thaliana, a model plant species. FLC acts as a strong repressor of flowering, and its regulation is crucial for the plant’s response to environmental cues such as temperature and photoperiod. In this article, we will evaluate the statements about FLC and its role in flowering regulation.

The Statements:

Let’s review the given statements and their validity:

1. Statement A: FLC is a strong repressor of flowering.

   • Correct.
     FLC functions as a repressor of flowering in Arabidopsis. It inhibits the expression of genes involved in floral initiation, preventing the plant from flowering too early. The higher the expression of FLC, the later the plant will flower.

2. Statement B: Higher expression of FLC induces early flowering.

   • Incorrect.
     This statement is false. In fact, higher expression of FLC leads to late flowering, not early flowering. FLC inhibits the flowering process by repressing genes that promote floral development. Therefore, plants with high levels of FLC expression flower later.

3. Statement C: FLC is activated by FRIGIDA (FRI).

   • Correct.
     FRIGIDA (FRI) is a key gene that activates FLC. The FRI protein enhances the transcription of FLC, leading to its increased expression, which then delays flowering. This interaction is a crucial part of the mechanism by which Arabidopsis responds to vernalization.

4. Statement D: Vernalization represses FLC.

   • Correct.
     Vernalization, the process of cold exposure, represses FLC. When Arabidopsis experiences a period of cold, it triggers epigenetic changes that reduce the expression of FLC, allowing the plant to flower after the cold period ends. This is an important mechanism for seasonal flowering regulation in plants.

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Analysis of the Correct Set of Statements:

Now, let’s look at the combination of statements:

• Option 1: A, B and C – This is incorrect because Statement B is false.

• Option 2: A, B and D – This is incorrect because Statement B is false.

• Option 3: B, C and D – This is incorrect because Statement B is false.

• Option 4: A, C and D – This is correct because all three of these statements are accurate.

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Correct Answer: Option 4

A, C and D are correct.

• Statement A is correct: FLC is a repressor of flowering.

• Statement C is correct: FLC is activated by FRIGIDA (FRI).

• Statement D is correct: Vernalization represses FLC.

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Conclusion

The FLOWERING LOCUS C (FLC) gene plays a critical role in regulating flowering time in Arabidopsis. Understanding how FLC functions as a repressor, and how it is influenced by factors such as FRIGIDA and vernalization, provides important insights into plant development and adaptation to environmental cues.