aerenchyma

Aerenchyma is a plant tissue composed of specialized parenchyma cells that contain large, interconnected air-filled spaces, known as lacunae. The spaces form within the tissue either by lysigenous processes, in which cells degrade and hollow out, or by schizogenous processes, in which cells separate and enlarge their intercellular spaces without extensive cell death. The resulting air channels run parallel to and connect with surface tissues, allowing gas movement between the atmosphere and interior plant tissues.

Aerenchyma is common in aquatic and wetland plants, including rice (Oryza sativa), reeds, cattails, and many mangroves. It often develops in roots and stems in response to hypoxic or anoxic soil conditions. Ethylene and other stress signals promote its formation by initiating cell separation or programmed cell death, facilitating the creation of internal air spaces that link to the plant’s surface.

The primary function of aerenchyma is to enable gas exchange between shaded, waterlogged tissues and the surrounding air. By providing continuous air channels, it supplies roots with oxygen needed for respiration and allows carbon dioxide to diffuse back toward shoots. In addition to supporting respiration in flooded soils, aerenchyma can reduce tissue density, contributing modestly to buoyancy in some species and influencing root-microbe interactions around the rhizosphere. Overall, aerenchyma is a key adaptation that enhances survival in low-oxygen environments.