Definition - What does Suberin mean?
Suberin is a waxy, waterproof substance found in the cells of root epidermis (outer surface), root endodermis (inner cell structure) and the periderm (bark) of woody plants (like cork). It is most often recognized in the wine world for the waterproofing effects it gives corks. In fact, the name “suberin” is derived from the latin name for the cork tree - Quercus Suber. Suberin creates impermeable, buoyant, elastic and fire retardant properties in cells.
WineFrog explains Suberin
In the endodermis, suberin is found in a band of cells called the Casparian strip or Casparian band. This band prevents water, nutrients and pathogens from passing into the inner part of the root system (the stele), protecting the plant from unnecessary or even damaging nutrients and pathogens; it also prevents over hydration of the root system. Instead, the water is sent through the “symplast” system (the inner part of the membrane), which filters the water and nutrients, ensuring the plant gets only what it needs to grow.
In the epidermis, suberin infuses the dead cells, creating a water-tight seal on the tree. This means that moisture from the roots can travel up the tree without fear of seeping out the flesh. With regards to wine, cork trees have an abundance of suberin in the bark (more so than other trees), which is one of the reasons cork bark is used in making cork closures.
Suberin is also a significant component in wound healing for plants. Since cork trees are high in suberin, the bark heals quickly making it a renewable resource.