The phenolic domain of potato suberin: Structural comparison with lignins

Natural and wound-healing potato periderms were analysed using thioacidolysis, a specific lignin degradative method. The nature and relative frequencies of phenylpropane units and of inter-unit bonds comprising this lignin-like domain were determined. Results confirmed that this domain contains guaiacyl G and syringyl S units, similar to lignins of woody angiosperms. The recovery yield of the G and S thioacidolysis monomers was, however, about one-tenth of that obtained for wood or straw lignified cell walls. This result suggests that G and S phenylpropane units are relatively few in suberized samples. These units occur in different ratios in the natural and wound potato periderms and are assembled with the same inter-unit bonds as those found in lignins of woody angiosperms, although in different proportions. Both the scarcity of the β - O −4 and β−1 bonds, and the high terminal to internal units ratio, suggest that this lignin-like domain is highly cross-linked.