Nanobubbles: a new paradigm for air-seeding in xylem

Area of Science:

• Plant Physiology
• Biophysics
• Water Transport

Background:

• Long-distance water transport in plants occurs under negative pressure, making it vulnerable to hydraulic failure.
• Gas bubble formation, particularly cavitation, is a primary cause of hydraulic failure.
• Nanoporous pit membranes between plant conduits are critical sites for bubble formation.

Purpose of the Study:

• To investigate the mechanism of nanobubble formation at plant pit membranes.
• To understand the role of nanobubbles in plant hydraulic failure and water transport.
• To evaluate the implications of nanobubbles for the cohesion-tension theory.

Main Methods:

• Theoretical analysis of fluid dynamics at the air-water interface within pit membrane pores.
• Consideration of factors influencing bubble stability, such as surfactants and gas supersaturation.

Main Results:

• Argues that nanobubbles are likely 'snapped off' within pit membranes due to local pressure increases.
• Nanobubbles can be stabilized by surfactants and gas supersaturation in plant sap.
• These nanobubbles may dissolve, fragment, or lead to embolism formation.

Conclusions:

• The formation of stable nanobubbles in plants is a plausible phenomenon.
• This hypothesis provides a new mechanism contributing to the cohesion-tension theory of plant water transport.
• Understanding nanobubble dynamics is crucial for predicting plant hydraulic function under stress.