48. Abscisic acid can be degraded by

(1) Oxidation and reduction

(2) Reduction and conjugation

(3) Oxidation and conjugation

(4) Light and reduction

Correct answer: (3) Oxidation and conjugation

Explanation:

• Abscisic acid (ABA) degradation in plants occurs mainly through oxidation and conjugation pathways.

• Oxidation typically involves hydroxylation enzymes that convert ABA into inactive forms.

• Conjugation refers to the attachment of sugar molecules or other groups to ABA, forming storage or transport conjugates like ABA-glucose ester, which can be reversibly activated or stored.

• Reduction is not a major pathway for ABA degradation.

• Light does not directly degrade ABA.

Option-wise:

• (1) Oxidation and reduction — incorrect due to reduction.

• (2) Reduction and conjugation — incorrect; oxidation not included.

• (3) Oxidation and conjugation — correct pathways for ABA degradation.

• (4) Light and reduction — incorrect; light not involved in ABA degradation.

  ABA degradation controls its cellular levels and signaling through enzymatic oxidation and conjugation, allowing plants to fine-tune stress responses and developmental processes effectively.