Guard Cells Integrate Light and Temperature Signals to Control Stomatal Aperture

Area of Science:

• Plant Physiology
• Molecular Biology
• Environmental Stress Response

Background:

• High temperatures trigger guard cell expansion, opening stomatal pores for essential leaf cooling.
• The precise mechanisms of high-temperature signal perception and transmission regulating stomatal aperture remain largely unelucidated.

Purpose of the Study:

• To investigate the molecular mechanisms underlying high temperature-mediated stomatal opening in *Arabidopsis thaliana*.
• To identify key signaling components and pathways involved in plant thermoadaptation.

Main Methods:

• Utilized a reverse-genetics approach in *Arabidopsis thaliana*.
• Analyzed phototropin-deficient mutants and impaired 14-3-3 protein interactions.
• Assessed guard cell transcript induction and plant evapotranspiration.

Main Results:

• High temperature-induced stomatal opening requires components shared with blue light signaling, indicating light-temperature pathway cross-talk.
• Phototropin photoreceptors, H+-ATPases, and 14-3-3 proteins are crucial for high temperature-mediated stomatal responses.
• Phototropin deficiency impairs leaf cooling and evapotranspiration under high temperatures.
• Disrupting 14-3-3 protein interactions inhibits stomatal opening but not heat-sensitive gene induction.

Conclusions:

• Plant responses to high temperatures involve cross-talk with light signaling pathways, particularly involving phototropins.
• 14-3-3 proteins play a critical role in transmitting high-temperature signals for stomatal opening.
• Evidence suggests an additional, distinct intracellular pathway for high-temperature response in guard cells.