Dynamic thermal imaging confirms local but not fast systemic ABA responses

Area of Science:

• Plant Physiology
• Plant Signaling
• Biophysics

Background:

• Abscisic acid (ABA) regulates stomatal aperture and water loss, crucial for plant survival.
• Traditional studies often use detached leaves or epidermal peels, limiting physiological context.
• Infrared thermal imaging is typically used for steady-state stomatal conductance, not dynamic responses.

Purpose of the Study:

• To investigate stomatal abscisic acid (ABA) responses in attached leaves across a time course using dynamic thermal imaging.
• To study stomatal behavior within the physiological context of the whole plant.
• To compare ABA responses in monocots and dicots and identify differences between leaf responses.

Main Methods:

• Utilized dynamic thermal imaging to observe stomatal ABA responses in whole plants.
• Applied low levels of ABA to attached leaves of monocots and dicots.
• Monitored leaf surface temperature changes over time to infer stomatal aperture changes.

Main Results:

• Detected stomatal responses to low ABA levels in both monocots and dicots.
• Observed variations in ABA responses among different leaves within the same plant.
• In Arabidopsis, found no evidence for rapid systemic ABA-induced stomatal closure.
• In barley, ABA-induced stomatal closure occurred without a requirement for exogenous nitrate.

Conclusions:

• Dynamic thermal imaging is a sensitive and robust tool for studying stomatal ABA responses in a whole plant context.
• Whole plant imaging revealed discrepancies with detached sample studies, highlighting the importance of physiological context.
• This approach complements traditional methods for investigating local and systemic stomatal responses and ABA signaling mechanisms.