Symplastic guard cell connections buffer pressure fluctuations to promote stomatal function in grasses

Area of Science:

• Plant Biology
• Plant Physiology
• Biophysics

Background:

• Stomata regulate plant gas exchange through guard cell shape changes.
• Grasses possess a unique stomatal structure, contributing to their ecological and agricultural importance.
• The discontinuous adjoining cell wall of grass guard cell pairs is a poorly understood feature.

Purpose of the Study:

• To investigate the functional significance of discontinuous symplastic connections in grass stomata.
• To explore the role of guard cell turgor pressure in stomatal pore aperture in grasses.
• To compare the mechanics of grass stomata with those of other land plants.

Main Methods:

• Demonstration of symplastic connections in various grass species.
• Finite element method (FEM) simulations to model stomatal mechanics.
• Analysis of guard cell turgor pressure effects on pore opening.

Main Results:

• Symplastic connections were confirmed in a range of grass species.
• Maximal stomatal pore opening in grasses occurs when guard cell turgor pressure is equal, particularly under low pressure.
• Turgor pressure differences have a lesser impact on kidney-shaped guard cells found in other plants.

Conclusions:

• The unique structure of grass stomata, specifically the discontinuous cell wall, facilitates efficient stomatal opening.
• Cellular mechanics involving equal turgor pressure in grass guard cells are key to their function.
• This mechanism likely played a role in the evolutionary success of grasses and crop development.