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Alpha-amylase secretion by single barley aleurone layers
Plant Physiology
|October 1, 1982
Summary
Gibberellic acid stimulates alpha-amylase secretion from barley aleurone layers, a process highly dependent on calcium ions (Ca2+). This enzyme release is metabolically linked and not diffusion-limited, as confirmed by various experimental conditions.
Area of Science:
- Plant Physiology
- Biochemistry
- Molecular Biology
Background:
- Aleurone layers in barley (Hordeum vulgare L.) are crucial for seed germination and nutrient mobilization.
- Alpha-amylase secretion is a key process regulated by plant hormones like gibberellic acid.
Purpose of the Study:
- To investigate the dynamics of alpha-amylase secretion from isolated barley aleurone layers.
- To elucidate the role of calcium ions (Ca2+) and metabolic processes in enzyme release.
Main Methods:
- Utilized an automated flow-through apparatus for real-time monitoring of alpha-amylase secretion.
- Investigated the effects of gibberellic acid, calcium ion concentration, ruthenium red, metabolic inhibitors (HCN), low temperature, and osmotic stress.
Main Results:
- Alpha-amylase release initiated 5-6 hours after gibberellic acid exposure, peaking at 10-12 hours.
- Enzyme secretion showed a strong Ca2+ dependence, with release ceasing upon Ca2+ withdrawal and resuming upon re-addition.
- Metabolic inhibitors, low temperature, and osmotic stress rapidly inhibited enzyme release, indicating a metabolically dependent process.
Conclusions:
- Gibberellic acid-induced alpha-amylase secretion is a Ca2+-dependent and metabolically regulated process in barley aleurone layers.
- The findings suggest that the cell wall structure may also play a role in regulating enzyme release.