Lignin， a three-component bio-polymers formed through ether and carbon-carbon bonds， constitutes a three-dimensional network structure within woody tissues. Primarily found in wood tissues， it serves to harden cell walls by creating an interwoven network， forming the main component of secondary cell walls. Lignin is predominantly located between cellulose fibers， providing compressive strength. In woody plants， lignin accounts for 25% of total organic matter， ranking as the second most abundant organic compound globally. Since lignin naturally interacts with cellulose and hemicellulose to form lignin-carbohydrate complexes (Lignin-Carbohydrate Complex)， researchers currently lack methods to isolate intact lignin without structural degradation.

The Lignin Stain Kit (Maule Method)consists of oxidizing agents， acidifying solutions， and alkaline color-developing solutions. Its core mechanism involves the reaction of vanillyl units (S units) in lignin with specific chemical reagents to produce purplish-red products， while guaiacyl units (G units) or other components remain colorless or show different colors， thereby enabling the differentiation of lignin types.This kit is suitable for dicotyledonous plants such as Arabidopsis thaliana.