52. Which or the following factors is known to be involved Postponing programmed cell death in cereal aleuroneuntil endosperm mobilization is complete?
    (1) Gibberellic acid
    (2) Abscisic acid
    (3) Acidic pH of the vacuoles
    (4) c-GMP mediated signal transduction pathway

Correct answer: (2) Abscisic acid

Explanation:

• Abscisic acid (ABA) is known to postpone programmed cell death (PCD) in cereal aleurone cells until the mobilization of endosperm reserves is completed. This delay ensures that hydrolytic enzymes are synthesized and secreted for nutrient mobilization before the aleurone cells start dying.

• Gibberellic acid (GA) promotes PCD in aleurone cells, leading to cell death following enzyme secretion.

• Acidic pH of vacuoles is a cellular condition but is not the key factor known for postponing PCD.

• c-GMP mediated signal transduction has roles in signaling but is not primarily identified for controlling PCD postponement in aleurone.

Option-wise:

• (1) Gibberellic acid — promotes PCD, not postpones it.

• (2) Abscisic acid — correct; postpones PCD in aleurone until nutrient mobilization completes.

• (3) Acidic pH of vacuoles — cellular condition, not main PCD postponement factor.

• (4) c-GMP mediated signal transduction — signaling pathway, not primary PCD regulator in this context.

  Abscisic acid is vital in regulating the timing of aleurone cell death in cereals, preventing premature loss of these cells to allow complete nutrient mobilization from the endosperm to support seedling growth.