Hydraulically based stomatal oscillations and stomatal patchiness in Gossypium hirsutum

Area of Science:

• Plant physiology
• Plant hydraulics
• Photosynthesis

Background:

• Stomatal oscillations are rhythmic fluctuations in stomatal aperture.
• These oscillations are thought to be related to feedback mechanisms within the plant's hydraulic system.
• Understanding stomatal oscillations is crucial for comprehending plant responses to environmental conditions.

Purpose of the Study:

• To investigate the characteristics of slow stomatal oscillations in cotton (Gossypium hirsutum L.).
• To explore the relationship between stomatal oscillations, intercellular CO2 concentrations (Ci), and plant hydraulics.
• To determine the potential link between stomatal oscillations and xylem embolism.

Main Methods:

• Studying stomatal oscillations in whole cotton plants exposed to light.
• Manipulating intercellular CO2 concentrations (Ci) in attached leaves.
• Measuring leaf-to-air vapor pressure difference (VPD).
• Utilizing chlorophyll fluorescence imaging to assess stomatal heterogeneity.
• Correlating stomatal oscillation phases with xylem embolism levels.

Main Results:

• Slow stomatal oscillations (70-95 min) were observed in cotton plants under light.
• Oscillations were not influenced by reduced intercellular CO2 concentrations (Ci) in intact leaves.
• Stomatal oscillations were synchronized across different leaves, even with altered VPD in one leaf.
• Stomatal heterogeneity was observed during the trough phase of oscillations.
• Stomatal oscillations correlated with xylem embolism, with more gas-filled vessels at the peak than at the troughs.

Conclusions:

• Slow stomatal oscillations in cotton are a whole-plant phenomenon linked to plant hydraulics.
• The oscillations are associated with stomatal heterogeneity and xylem embolism.
• These findings provide insights into the complex feedback mechanisms regulating stomatal behavior and water transport in plants.