Mechanical advantage makes stomatal opening speed a function of evaporative demand

Area of Science:

• Plant Physiology
• Plant Anatomy
• Photosynthesis Research

Background:

• Stomatal opening allows atmospheric CO2 uptake for photosynthesis, vital for land plants.
• The kinetics of stomatal opening are critical for carbon gain, especially with fluctuating light.
• The influence of evaporative demand, measured by vapor pressure deficit (VPD), on stomatal opening speed is not well understood.

Purpose of the Study:

• To investigate if mechanical interactions between guard cells and epidermal cells affect the speed of stomatal opening.
• To determine how evaporative demand influences the kinetics of light-induced stomatal opening across diverse plant species.

Main Methods:

• Examined stomatal opening speed in response to light across a range of VPDs.
• Studied seven plant species representing diverse guard cell and epidermal cell mechanical interactions.
• Compared responses in angiosperms, Marsilea ferns, gymnosperms, and other ferns.

Main Results:

• Stomatal opening speed correlated with evaporative demand in angiosperms and Marsilea, species with guard cell-epidermal cell mechanical interactions.
• Species lacking these specific mechanical interactions (gymnosperms, other ferns) showed no change in stomatal opening speed across varying VPDs.

Conclusions:

• Guard cell and epidermal cell mechanical interactions appear to play a significant role in regulating stomatal responsiveness to light.
• These mechanical interactions may be key to adapting stomatal function under varying evaporative demand.