Lignify

Lignify is a verb meaning to convert or become lignified, that is, to become rich in lignin or to form a lignified tissue. In plants, lignification is the biological process by which cell walls acquire lignin, a complex phenolic polymer that strengthens tissues and makes them more resistant to decay and water loss. Lignification typically occurs during secondary cell wall development in vascular tissues such as xylem fibers and vessel elements, and can also occur as part of wound responses.

Biochemical basis: Lignin is deposited from monolignols produced by the phenylpropanoid pathway, including p-coumaryl, coniferyl, and sinapyl alcohols. These are transported to the cell wall and randomly polymerized by oxidative enzymes such as peroxidases and laccases into a three-dimensional network that intertwines with cellulose and hemicellulose.

Functions and consequences: Provides mechanical strength, rigidity, and water impermeability; facilitates long-distance water transport; increases resistance to pathogens but reduces digestibility of plant biomass.

Context and applications: In forestry and botany, lignification marks wood formation; the degree and composition of lignin (e.g., syringyl/guaiacyl ratio) influence wood properties and pulp processing. In paper production, lignin removal is essential; chemical pulping aims to break lignin-lignin bonds. In biofuels and animal feeds, high lignin content can hinder digestibility and saccharification.