Question Details

Gibberellins can facilitate seed germination due to their influence on

Options

A

synthesis of abscisic acid

B

rate of cell division

C

production of hydrolyzing enzymes

D

absorption of water through the hard seed coat

Correct Answer :

production of hydrolyzing enzymes

Solution :

The correct option is production of hydrolyzing enzymes.

Seed germination is a highly regulated physiological process, and gibberellins (a class of plant hormones) play a pivotal role in initiating it. The step-by-step mechanism of how gibberellins facilitate seed germination is detailed below:

1. Water Imbibition:
The germination process begins when a dry seed absorbs water (imbibition). This hydration activates the embryo within the seed.

2. Release of Gibberellins:
Once activated, the embryo synthesizes and releases gibberellins (specifically gibberellic acid, or GA). These hormones diffuse from the embryo into the surrounding endosperm and reach the aleurone layer, which is the protein-rich outer layer of the endosperm.

3. Synthesis of Hydrolyzing Enzymes:
Upon reaching the aleurone layer, gibberellins trigger signaling pathways that induce the synthesis and secretion of various hydrolyzing enzymes. The most notable of these enzymes is α-amylase, alongside others like proteases, hemicellulases, and lipases.

4. Mobilization of Food Reserves:
These newly synthesized hydrolyzing enzymes are secreted into the endosperm, where they break down complex, insoluble stored food reserves into simpler, soluble molecules. For instance, starch is hydrolyzed into soluble sugars (like maltose and glucose).

5. Embryo Growth:
The soluble nutrients are absorbed by the growing embryo, providing the essential energy and building blocks required for cellular activities, growth, and the eventual emergence of the seedling.

Therefore, gibberellins facilitate germination primarily by inducing the production of hydrolyzing enzymes that mobilize the seed's stored nutrients.

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