Nobody's perfect: can irregularities in pit structure influence vulnerability to cavitation?

Area of Science:

• Plant Physiology
• Xylem Anatomy
• Biophysics

Background:

• Xylem vulnerability to cavitation is influenced by pit properties like membrane thickness and porosity.
• While mean pit characteristics are important, structural variability within species is significant.
• The rare pit hypothesis suggests single, more permeable pits can initiate air-seeding.

Purpose of the Study:

• To investigate the role of pit structural variability in xylem cavitation.
• To identify specific pit aberrations that may lead to air-seeding.
• To explore the link between pit anomalies and plant stress responses.

Main Methods:

• Analysis of pit membrane thickness, porosity, torus-to-aperture ratio, and pit chamber depth.
• Evaluation of pit structure variability within species and pit fields.
• Modeling of air-seeding based on pit morphology.

Main Results:

• Pit structural irregularities, such as rare large pores or torus extensions, can facilitate air-seeding.
• These aberrations, whether developmental or stress-induced, increase cavitation vulnerability.
• Pit structure anomalies suggest a connection between abiotic/biotic stresses and xylem function.

Conclusions:

• Xylem cavitation is sensitive to rare pit structural anomalies, not just average traits.
• Pit aberrations act as critical points for air-seeding, impacting plant hydraulic safety.
• Interactions between environmental stresses and xylem physiology are mediated by pit structure.