Morphological variation of intervessel pit membranes and implications to xylem function in angiosperms

Area of Science:

• Plant anatomy and physiology
• Wood structure and function
• Plant hydraulics

Background:

• Intervessel pit membranes in xylem play a role in plant hydraulic resistance and embolism vulnerability.
• Understanding pit membrane structure is key to understanding plant water transport efficiency.

Purpose of the Study:

• To investigate the structural variation in intervessel pit membranes across hardwood species.
• To correlate pit membrane structure (thickness, porosity) with hydraulic traits like air-seeding thresholds.

Main Methods:

• Scanning Electron Microscopy (SEM) was used to examine pit membrane structure in 26 hardwood species.
• Measurements of pit membrane thickness and maximum pore diameter were taken.
• Pore diameters from SEM were compared with air-seeding thresholds in a subset of species.

Main Results:

• Significant variation in pit membrane thickness (70-1892 nm) and pore diameter (10-225 nm) was observed.
• A strong negative correlation between pit membrane thickness and pore diameter was found (thinner = more porous).
• SEM-derived pore diameters provided a relative estimate of air-seeding thresholds, though absolute values require caution.

Conclusions:

• Pit membrane structure exhibits substantial diversity, influencing plant hydraulic function.
• SEM underestimates in situ pit membrane porosity; findings offer relative insights into air-seeding resistance.
• Variations in pit membrane thickness and porosity have significant implications for plant adaptation to drought and hydraulic efficiency.