Plant Adaptations to Anoxic Conditions

Plant Adaptations to Anoxic Conditions

• Pressurized gas flow is an adaptation in some plant species to cope with anoxic conditions, where oxygenated air is pumped down to the root system.
• This adaptation was first observed in the water lily species and has since been discovered in giant reed and alder shrubs.
• Passive diffusion is the main transport mechanism in plants, allowing oxygen to flow from the atmosphere to the root system.
• In plants with pressurized gas flow, pressure is generated in young leaves, forcing air down through the stem, oxygenating the root system, and eventually flowing out of older leaves.
• A single floating water lily leaf can take in up to 22 liters of air per day, making it an effective process for oxygenating the root system.
• The process works by creating an air pressure gradient from younger leaves to older leaves, as older leaves become leakier and lose their capacity to support internal air pressure.

Radial Oxygen Loss

• Radial oxygen loss is a physiological adaptation in plants to wetland environments, where oxygen leaks out into the surrounding soil environment from the roots.
• This adaptation has two benefits: it oxidizes toxic products caused by reducing conditions in wetland soils, preventing them from building up to harmful levels around the roots, and it supplies oxygen to nitrifying bacteria, which transform ammonium to nitrate, a readily available form of nitrogen for plants.

Tolerance to Anaerobic Respiration Byproducts

• Some wetland plants have adapted to tolerate the toxic end products of anaerobic respiration, such as ethanol and acetaldehyde.
• These plants have either efficient means of tolerating these byproducts or exporting them from the roots.