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Guard cell starch concentration quantitatively related to stomatal aperture
1Plant Biology Program, Department of Biology (Box 1137), Washington University, Saint Louis, Missouri 63130.
Plant Physiology
|July 1, 1979
Summary
Guard cells in Vicia faba store more starch when stomata are closed. Soluble sugars increase in guard cells when stomata open, suggesting starch breakdown fuels opening.
Area of Science:
- Plant Physiology
- Biochemistry
- Plant Cell Biology
Background:
- Stomatal apparatus regulation is crucial for plant gas exchange and water balance.
- Guard cells control stomatal aperture, influenced by environmental factors and internal signaling.
- Carbohydrate metabolism in guard cells is implicated in stomatal movement.
Purpose of the Study:
- To quantitatively compare carbohydrate levels (starch and sucrose) in Vicia faba guard cells between open and closed stomata.
- To investigate the role of starch degradation in providing carbon skeletons for anion synthesis during stomatal opening.
Main Methods:
- Quantitative histochemical techniques were employed to measure carbohydrate concentrations.
- Comparisons were made between paired leaflets to minimize experimental error.
- Stomatal opening was induced by light and reduced CO(2); closure was induced by darkness.
Main Results:
- Guard cell starch concentration was significantly higher (72 +/- 16 mmol/kg dry weight) in closed stomata compared to open stomata.
- Guard cell sucrose concentration was significantly higher (45 +/- 7 mmol/kg dry weight) in open stomata compared to closed stomata.
- Starch concentration variation within leaflets was minimal, supporting its role in guard cell function.
Conclusions:
- Starch degradation in guard cells likely provides carbon skeletons for anion synthesis during stomatal opening.
- Increased soluble sugars in guard cells correlate with stomatal opening in Vicia faba.
- These findings support a metabolic model for stomatal regulation involving carbohydrate interconversion.
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