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Suberin: the plant waterproofing polymer

Suberin is a hydrophobic plant biopolymer that forms protective barriers in bark, roots and wounds, limiting water and solute movement and helping resist pathogens and physical damage.

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Overview

Suberin is a complex, waxy biopolymer produced by many land plants. It is deposited in cell walls where an impermeable barrier is required, notably in cork cells, the root endodermis and in wound tissues. Suberin reduces water loss, restricts uncontrolled solute movement, and contributes to resistance against pathogens and insects.

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Composition and characteristics

Chemically, suberin is not a single molecule but a cross-linked matrix made from long-chain fatty acids and glycerol together with aromatic (phenolic) components. This combination of aliphatic (lipid-like) and phenolic domains gives suberin its hydrophobic, durable and flexible properties. In microscopy it appears as lamellar deposits or a continuous layer lining the inner face of cell walls.

Where it occurs

Typical locations include:

  • cork (phellem) of bark, where it forms the outer protective layer;
  • the Casparian strip and suberized cell layers in roots, which regulate water and ion uptake;
  • wound periderms formed after tissue damage, sealing off damaged areas.

Functions, uses and importance

Functionally, suberin limits water loss and radial flow of solutes, and provides a chemical and physical barrier to pathogens. Economically, the best-known suberin-rich material is cork harvested from the cork oak (Quercus suber), used for bottle stoppers, insulation and other products. In agriculture and ecology, suberization affects drought tolerance, root function and post-harvest storage of tubers and fruits.

Suberin is distinct from cutin (the lipid polymer of leaf surfaces) and from lignin (an aromatic polymer that provides rigidity). The process of forming suberin is called suberization and is a controlled, developmentally regulated response. Because of its mixed chemical nature it remains a focus of research for biomaterials and plant physiology.

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AlegsaOnline.com Suberin: the plant waterproofing polymer

URL: https://en.alegsaonline.com/art/94473

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