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Stomatal responses to humidity in isolated epidermes.
Joseph C Shope1, David Peak, Keith A Mott
1Biology Department, Utah State University, Logan, UT 84322-5305, USA.
Plant, Cell & Environment
|June 11, 2008
Summary
Guard cells regulate stomatal pores by hydrating and dehydrating directly from water vapor. This process, crucial for plant transpiration, depends on internal vapor pressure more than external.
Area of Science:
- Plant Physiology
- Plant Anatomy
Background:
- Guard cells control stomatal aperture, regulating gas exchange and transpiration.
- Understanding guard cell hydration mechanisms is key to plant water relations.
Purpose of the Study:
- To investigate the direct water source for guard cell hydration and dehydration.
- To determine the role of internal and external water vapor pressure in stomatal response.
Main Methods:
- Experiments were conducted on isolated epidermes of Tradescantia pallida and Vicia faba.
- Stomatal aperture changes were measured under varying humidity conditions using helium-oxygen air.
Main Results:
- Guard cells hydrate and dehydrate directly from water vapor, not epidermal tissue.
- Stomatal response is more sensitive to inside vapor pressure than outside.
- Stomatal aperture aligns with water potential equilibrium between guard cells and pore-bottom air.
Conclusions:
- Guard cell hydration is primarily driven by water vapor exchange with the air near the stomatal pore.
- While isolated epidermis responses are equilibrium-based, whole-leaf responses to humidity may differ.
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