High-density nodal diaphragms in stems slow down, but do not obstruct, longitudinal oxygen diffusion during partial...

Area of Science:

• Plant Biology
• Physiology
• Ecology

Background:

• Alternanthera philoxeroides is a flood-tolerant plant facing hypoxic stress.
• Its stem pith cavity is interrupted by nodal diaphragms, raising questions about internal gas transport functionality.

Purpose of the Study:

• To investigate the role of discontinuous stem pith cavities in internal gas transport.
• To assess oxygen (O2) transport capacity, tissue O2 status, and growth responses to restricted O2 supply.

Main Methods:

• Assessed diffusive O2 transport capacity in stems.
• Measured tissue O2 status in intact plants.
• Evaluated whole-plant growth under partial submergence with manipulated O2 supply.

Main Results:

• Stem pith cavities are the primary pathway for O2 diffusion.
• Blocking even one internode significantly reduced O2 flux to lower sections.
• Reduced O2 flux led to decreased growth in partially submerged plants.

Conclusions:

• Discontinuous pith cavities are functional for internal O2 transport in Alternanthera philoxeroides.
• This transport is vital for maintaining plant growth under submergence.
• A predictive model was developed for comparing O2 transport across species.