periarbuscular

Periarbuscular is an adjective used in plant biology to describe structures, spaces, and processes located at the interface surrounding an arbuscule within a plant root cortical cell, in arbuscular mycorrhizal (AM) symbioses. In AM associations, fungi of the Glomeromycota colonize the root cortex and form arbuscules, which are enveloped by a plant-derived periarbuscular membrane.

The periarbuscular space is the narrow compartment between the fungal plasma membrane and the surrounding periarbuscular membrane. This interface functions as the primary site for bidirectional nutrient exchange between the plant and the fungus. Plant transporters localized to the periarbuscular membrane mediate uptake of nutrients such as phosphorus and nitrogen, while the fungus supplies carbon compounds to the plant.

Periarbuscular components include the membrane itself, the adjacent space, and associated protein complexes involved in signaling and transport. The term is commonly used in microscopy and ultrastructural studies to distinguish features at the arbuscular interface from other intracellular or extracellular compartments.

The concept of the periarbuscular interface is central to understanding how AM symbioses regulate nutrient acquisition, carbon allocation, and plant root physiology, as well as how these interactions respond to environmental factors such as soil phosphorus availability.

See also: arbuscular mycorrhizal symbiosis, arbuscule, periarbuscular membrane, periarbuscular space.